JP7514058B2 - Photosensitive film laminate and its cured product, and electronic parts - Google Patents

Description

The present invention relates to a photosensitive film laminate, and more specifically, to a photosensitive film laminate that can be suitably used to form a hollow structure in an electronic component having a hollow structure, the cured product thereof, and the electronic component.

In recent years, there has been an increasing demand for electronic devices to be smaller and more functional, and electronic components used therein are also required to be smaller, thinner, and more multifunctional. In particular, the development of microelectronic components such as image sensors, such as CMOS and CCD sensors, gyro sensors using MEMS (Micro Electro Mechanical Systems) technology, which integrates mechanical elements and electronic circuit elements on a single substrate using semiconductor microfabrication technology, and surface acoustic wave (SAW) filters, which are packages of elements that perform specific electrical functions by forming electrode patterns and microstructures on the surface of a single crystal wafer, is attracting attention. In these microelectronic components, a hollow structure is formed to prevent other objects from contacting the active surface (moving part) of the sensor element and to protect the sensor element from moisture, dust, etc., and the sensor, etc. are placed inside the hollow structure.

Conventionally, the hollow structures of electronic components such as those described above have been formed by processing and bonding inorganic materials. However, there is a demand for reducing manufacturing costs and further miniaturization, and methods of forming hollow structures using photosensitive resins instead of inorganic materials have begun to be considered. For example, it has been proposed to laminate permanent resist and form walls (wall surfaces) and lids using photolithography technology to create a hollow structure (for example, Patent Document 1).

Publication No. 2009/151050

Electronic components with a hollow structure, such as the SAW filters described above, are manufactured as package structures with external terminals and external electrodes that are electrically connected to the wiring electrodes of the piezoelectric substrate for mounting on a mounting substrate. In order to ensure connection reliability with the external wiring, internal conductors are formed by plating or other methods in the vicinity of the walls and lid that form the hollow structure. In addition, to protect the elements and improve handling, the hollow structure and the adjacent parts are sealed with resin by transfer molding or other methods.

However, when a hollow structure is formed using permanent resist, it has been confirmed that plating and other materials can peel off when an internal conductor is formed in the vicinity.

Therefore, the present invention aims to provide a photosensitive film laminate suitable for forming a hollow structure, which can suppress peeling of plating, etc., in the vicinity of the hollow structure in electronic components having a hollow structure, such as SAW filters. Another object of the present invention is to provide a cured product formed using the photosensitive film laminate, and an electronic component having a hollow structure.

The above-mentioned hollow structure can be formed by using a resin in a method of forming a hollow structure by laminating several layers of photosensitive film, exposing and developing them to form walls, placing another photosensitive film on the top of the wall, exposing and developing it to a predetermined shape to form a lid, and thermally curing the photosensitive resin to form a hollow structure. The inventors have intensively studied the above problem and found that when a hollow structure is formed using a photosensitive film as described above, a small amount of the developer used in the development process remains in the wall and lid parts that make up the hollow structure, and this developer seeps out from the interface, inhibiting adhesion to plating, etc., and making the film more likely to peel off. As a result of further investigation, it has been found that by using a photosensitive film laminate with a protective film, in which the change over time in the surface form after the protective film is peeled off to expose the photosensitive film surface, in the formation of a hollow structure, it is possible to suppress inhibition of adhesion to plating, etc., and to manufacture electronic components with high-quality hollow structures.

That is, the photosensitive film laminate of the present invention is a photosensitive film laminate including, in order, a support film, a photosensitive film formed from a photosensitive composition, and a protective film,
The protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface, and the photosensitive film surface is left for 1 minute in an environment of 23° C. and 42% relative humidity. The arithmetic average surface roughness of the photosensitive film surface after the exposure is Ra1.
The protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface. After leaving the photosensitive film for 180 minutes in an environment of 23° C. and a relative humidity of 42%, the arithmetic average surface roughness of the photosensitive film surface is Ra2.
In this case, the following formula:
Ra1≧0.10 μm and 0.40≦Ra2/Ra1<1.00
The present invention is characterized in that:

In an embodiment of the present invention, the protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface, and the maximum height of the photosensitive film surface after being left for 1 minute in an environment of 23° C. and a relative humidity of 42% is Ry1,
The protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface, and the photosensitive film surface is left for 180 minutes in an environment of 23° C. and 42% relative humidity. The maximum height of the photosensitive film surface is Ry2,
In this case, the following formula:
Ry1≧1.00 μm and 0.30≦Ry2/Ry1<1.00
It is preferable that the following is satisfied.

In an embodiment of the present invention, it is preferable that the photosensitive composition contains a photocurable compound.

In an embodiment of the present invention, it is preferable that the photosensitive composition further contains a photopolymerization initiator.

In addition, in an embodiment of the present invention, the photosensitive film laminate is preferably used to form a lid or wall portion that constitutes a hollow structure in an electronic component having the hollow structure.

In another aspect of the present invention, the cured product is characterized in that it is obtained by curing the photosensitive film of the above-mentioned photosensitive film laminate.

In addition, an electronic component according to another aspect of the present invention is characterized by having the above-mentioned cured product.

In addition, an electronic component according to another aspect of the present invention has a hollow structure consisting of a wall portion and a lid portion, and it is preferable that either or both of the wall portion and the lid portion are made of the above-mentioned cured product.

According to the present invention, it is possible to provide a photosensitive film laminate suitable for forming a hollow structure, which can suppress peeling of plating or the like in the vicinity of the hollow structure in an electronic component having a hollow structure. In addition, according to another aspect of the present invention, it is possible to provide a cured product and an electronic component formed using the photosensitive film laminate.

1A to 1C are schematic cross-sectional views showing the procedure for producing the test substrates produced in Examples 4 and 5. 1A to 1C are schematic cross-sectional views showing the procedure for producing the test substrates produced in Examples 4 and 5. 1A to 1C are schematic cross-sectional views showing the procedure for producing the test substrates produced in Examples 4 and 5. 1A to 1C are schematic cross-sectional views showing the procedure for producing the test substrates produced in Examples 4 and 5.

<Photosensitive Film Laminate>
The photosensitive film laminate according to the present invention includes, in this order, a support film, a photosensitive film formed from a photosensitive composition, and a protective film. Hereinafter, each component constituting the photosensitive film laminate of the present invention will be described. In addition, unless otherwise specified, in this specification, a numerical range represented by the symbol "-" means a range including the upper and lower limit numerical values (i.e., a range not less than the lower limit and not more than the upper limit).

[Support film]
The support film constituting the photosensitive film laminate according to the present invention supports the photosensitive film, and can be used without any particular limitation as long as it can achieve the function. For example, a film made of a thermoplastic resin such as a polyester film such as polyethylene terephthalate or polyethylene naphthalate, a polyimide film, a polyamideimide film, a polypropylene film, or a polystyrene film can be preferably used. In addition, when the thermoplastic resin film is used, a filler may be added to the resin when forming the film (kneading treatment), a matte coating (coating treatment), a blast treatment such as a sandblasting treatment on the film surface, or a hairline processing or chemical etching treatment may be performed. Among these, a polyester film can be preferably used from the viewpoint of heat resistance, mechanical strength, handling, etc. The support film may be a single layer, or two or more layers may be laminated.

For the thermoplastic resin film described above, it is preferable to use a film that has been uniaxially or biaxially stretched in order to improve its strength.

The thickness of the support film is not particularly limited, but is generally selected appropriately depending on the application, within the range of 10 μm or more and 3,000 μm or less.

[Photosensitive film]
The photosensitive film constituting the photosensitive film laminate according to the present invention is formed from a photosensitive composition. That is, the photosensitive film can be formed by applying a photosensitive composition containing each component described later to one side of a support film and drying it. The photosensitive film is formed into a predetermined shape by exposure and development, and then the photosensitive composition is cured to become a cured product. Therefore, when the protective film is peeled off from the photosensitive film laminate to expose the surface of the photosensitive film, the photosensitive composition is in an uncured state, so the surface morphology of the photosensitive film changes over time. In the present invention, it has been found that there is some relationship between the change in the surface morphology of the photosensitive film over time and the peeling of plating, etc., and by making a photosensitive film laminate that satisfies the following conditions, if a hollow structure of an electronic component is formed using the photosensitive film laminate, the adhesion with plating, etc. is suppressed from being hindered, and an electronic component having a high-quality hollow structure can be realized.

In the present invention, the protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface, and the photosensitive film surface is left for 1 minute in an environment of 23° C. and a relative humidity of 42%. The arithmetic mean surface roughness of the photosensitive film surface after this is Ra1,
The protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface. After leaving the photosensitive film for 180 minutes in an environment of 20° C. and a relative humidity of 42%, the arithmetic average surface roughness of the photosensitive film surface is Ra2.
In this case, the following formula:
Ra1≧0.10 μm and 0.40≦Ra2/Ra1<1.00
It is important to satisfy the above. When the photosensitive film has an uneven surface with a predetermined arithmetic mean surface roughness when the protective film is peeled off, the uneven surface tends to gradually become flat, and the surface morphology changes over time. In the present invention, by focusing on this change in surface morphology over time and using a photosensitive film that only undergoes a specific change in surface morphology, peeling of plating, etc. in the vicinity of the hollow structure can be suppressed.

In the present invention, the arithmetic average surface roughness Ra1 of the photosensitive film on the surface that was in contact with the protective film after the protective film is peeled off is 0.10 μm or more, preferably 0.15 μm or more, and more preferably 0.20 μm or more. When an upper limit is set, it is preferably 1.00 μm or less, more preferably 0.80 μm or less, and even more preferably 0.60 μm or less. Note that Ra1 is defined as the value measured by peeling off the protective film to expose the photosensitive film surface and leaving it for 1 minute in an environment of 23° C. and relative humidity 42%.

From the viewpoint of further suppressing peeling of plating, etc., the maximum height Ry1 of the photosensitive film on the surface that was in contact with the protective film after the protective film is peeled off is preferably 1.00 or more, more preferably 1.20 μm or more, and even more preferably 1.40 μm or more. When an upper limit is set, it is preferably 5.00 μm or less, more preferably 4.00 μm or less, and even more preferably 3.00 μm or less. Ry1 is defined as the value measured by peeling off the protective film to expose the photosensitive film surface and leaving it for 1 minute in an environment of 23° C. and relative humidity 42%.

The change in shape of the photosensitive film surface over time can be evaluated by the ratio of the arithmetic mean surface roughness after a certain time has passed to the arithmetic mean surface roughness (i.e., Ra1) immediately after peeling off the protective film. In the present invention, if the arithmetic mean surface roughness of the photosensitive film on the surface that was in contact with the protective film after peeling off the protective film from the photosensitive film laminate to expose the photosensitive film surface and leaving it in an environment of 23°C and relative humidity 42% for 180 minutes is Ra2, then if the photosensitive film laminate satisfies 0.40≦Ra2/Ra1<1.00, peeling of plating, etc. in the vicinity of the hollow structure can be suppressed. The reason for this is unclear, but is thought to be as follows. That is, in a photosensitive film laminate with a protective film, after the protective film is peeled off to expose the photosensitive film surface, the surface shape having a certain roughness gradually changes over time, and if the rate of such change is constant, the degree of adhesion between the base in the case of a wall material and the wall material in the case of a lid material becomes more appropriate, preventing the remaining developer used during development from penetrating into the periphery of the hollow structure, and as a result, it is presumed that peeling of plating, etc. caused by the remaining developer can be suppressed. However, this is merely a guess and is not necessarily limited to this. In the present invention, the place where the protective film is peeled off to expose the photosensitive film surface and left for 180 minutes is under a yellow lamp.

From the viewpoint of preventing peeling due to a moderate change in shape over time, the surface of the photosensitive film is preferably in the range of 0.50≦Ra2/Ra1≦0.95, and more preferably in the range of 0.60≦Ra2/Ra1≦0.90.

In addition, if the protective film is peeled off from the photosensitive film laminate to expose the photosensitive film surface, and the photosensitive film is left for 180 minutes in an environment of 23°C and 42% relative humidity, and the maximum height of the photosensitive film on the surface that was in contact with the protective film is Ry2, then a photosensitive film laminate that satisfies 0.30≦Ry2/Ry1<1.00 can further suppress peeling of plating, etc. In the present invention, the location where the photosensitive film surface is left exposed after the protective film is peeled off for 180 minutes is under a yellow lamp.

From the viewpoint of suppressing peeling due to a moderate change in shape over time on the surface of the photosensitive film, it is preferable that 0.35≦Ry2/Ry1≦0.80, and more preferably 0.40≦Ry2/Ry1≦0.70.

It is also preferable that the arithmetic surface roughness Ra'' and maximum height Ry'' of the surface of the photosensitive film in contact with the support film are in the same range and change rate as the arithmetic surface roughness Ra and maximum height Ry of the surface in contact with the protective film. This is particularly effective when there is no protective film, and the photosensitive film laminate is provided in this order with a support film and a photosensitive film formed from a photosensitive composition. In such a case, it is preferable that the support film is made of the same material and has the same thickness as the protective film described below.

In the present invention, the above-mentioned "arithmetic mean surface roughness Ra" and "maximum height Ry" refer to values measured using a measuring device conforming to JIS B0601-1994. A specific measurement method will be described below. The arithmetic mean surface roughness Ra and maximum height Ry can be measured using a shape measuring laser microscope (for example, VK-X100 manufactured by Keyence Corporation). After starting the shape measuring laser microscope (VK-X100) main body (control unit) and the VK observation application (VK-H1VX manufactured by Keyence Corporation), the sample to be measured (photosensitive film) is placed on the x-y stage. Rotate the lens revolver of the microscope unit (VK-X110 manufactured by Keyence Corporation) to select an objective lens with a magnification of 10 times, and roughly adjust the focus and brightness in the image observation mode of the VK observation application (VK-H1VX manufactured by Keyence Corporation). Operate the xy stage to adjust the part of the sample surface you want to measure to be at the center of the screen. Change the 10x objective lens to 50x and focus on the sample surface using the autofocus function of the image observation mode of the VK observation application (VK-H1VX). Select the simple mode in the shape measurement tab of the VK observation application (VK-H1VX), press the measurement start button, measure the surface shape of the sample, and obtain a surface image file. Start the VK analysis application (VK-H1XA, manufactured by Keyence Corporation), display the obtained surface image file, and then perform tilt correction. The observation measurement range (horizontal) in the measurement of the surface shape of the sample is 270 μm. Display the line roughness window, select JIS B0601-1994 in the parameter setting area, select the horizontal line from the measurement line button, display the horizontal line anywhere in the surface image, and press the OK button to obtain the numerical values of the arithmetic mean surface roughness Ra and maximum height Ry. Furthermore, horizontal lines are displayed at four different points in the surface image, and the numerical values of the arithmetic mean surface roughness Ra and maximum height Ry are obtained for each. The average value of the five obtained numerical values is calculated, and is set as the arithmetic mean surface roughness Ra and maximum height Ry value of the sample surface. In the measurement of the arithmetic mean surface roughness Ra and maximum height Ry described above, the photosensitive film in a state before the curing process by exposure to light or the like is used as the measurement sample. In the case where a protective film is laminated on the photosensitive film as a laminate as in the present invention, the measurement sample is used in a state where the protective film is peeled off before lamination to the substrate. In this case, the "arithmetic mean surface roughness Ra" and "maximum height Ry" of the sample surface are measured immediately (1 minute) and 180 minutes after the protective film is peeled off to expose the photosensitive film. In the present invention, the measurement environment is a temperature of 23°C and a relative humidity of 42%.

To make the surface shape of the photosensitive film fall within the above-mentioned specific ranges of arithmetic mean surface roughness Ra and maximum height Ry, known and commonly used methods can be applied. In particular, from the viewpoint of ease of forming the surface shape as described above, the photosensitive film can be formed using a protective film as described below in which the arithmetic mean surface roughness Ra and maximum height Ry have been adjusted. In addition, the roughness of the photosensitive film surface may be adjusted by attaching a protective film having a specific arithmetic mean surface roughness Ra and maximum height Ry, peeling the protective film, and then attaching another protective film having a different arithmetic mean surface roughness Ra and maximum height Ry to the photosensitive film surface.

In addition, the change over time in the surface morphology of the photosensitive film after the protective film is peeled off can be adjusted by the type and amount of components contained in the photosensitive composition before curing that constitutes the photosensitive film. For example, it can be adjusted by blending materials with different solubility parameters (SP values), using materials with appropriate glass transition temperatures (Tg) and weight average molecular weights, or using fillers appropriately, but is not limited to these. In the present invention, the photosensitive composition that forms the photosensitive film is not particularly limited in composition, but may contain a photocurable compound, a photopolymerization initiator, a thermal crosslinking agent, an inorganic filler, etc. Below, each component that constitutes the photosensitive composition will be described.

[Photocurable compound]
The photosensitive composition used in the photosensitive film laminate of the present invention contains a component that is cured by irradiation with ionizing radiation such as ultraviolet light, and an example thereof is a photocurable compound. The photocurable compound is a compound having an ethylenically unsaturated double bond, and the compound includes any of resins, oligomers, and monomers. Examples of such photocurable compounds include alkyl (meth)acrylates such as 2-ethylhexyl (meth)acrylate and cyclohexyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; mono- or di(meth)acrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, and dipentaerythritol. , polyhydric (meth)acrylates of polyhydric alcohols such as trishydroxyethyl isocyanurate or their ethylene oxide or propylene oxide adducts, (meth)acrylates of ethylene oxide or propylene oxide adducts of phenols such as phenoxyethyl (meth)acrylate and polyethoxydi(meth)acrylate of bisphenol A, (meth)acrylates of glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether and triglycidyl isocyanurate, and melamine (meth)acrylate. In this specification, (meth)acrylate is a general term for acrylates, methacrylates and mixtures thereof, and the same applies to other similar expressions.

In addition to the above, examples of the polymerizable compound include a polymerizable compound having an amide bond and at least one ethylenically unsaturated group having two or more groups, and a urethane monomer or urethane oligomer such as a (meth)acrylate compound having a urethane bond.

Furthermore, the photocurable compound can be made into a carboxyl group-containing photosensitive resin by reacting an epoxy resin, a phenolic resin, or the like with an unsaturated carboxylic acid such as acrylic acid or methacrylic acid. Such a carboxyl group-containing photosensitive resin can be polymerized or crosslinked by irradiation with light and cured, and is preferable in that it can be developed not only in a solvent but also in an alkaline state due to the inclusion of a carboxyl group. It is particularly preferable in that it can be developed well in a weakly alkaline developer, specifically a developer having a pH of 7.0 or more and 12.0 or less.

Specific examples of the carboxyl group-containing photosensitive resin include the compounds (which may be either oligomers or polymers) listed below.
(1) A carboxyl group-containing photosensitive resin obtained by reacting a difunctional or more polyfunctional (solid) epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl group present in the side chain;
(2) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy resin in which the hydroxyl groups of a bifunctional (solid) epoxy resin are further epoxidized with epichlorohydrin, with (meth)acrylic acid, and adding a dibasic acid anhydride to the resulting hydroxyl groups;
(3) A carboxyl group-containing photosensitive resin obtained by reacting an epoxy compound having two or more epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule and an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid;
(4) A carboxyl group-containing photosensitive resin obtained by reacting a reaction product obtained by reacting a compound having two or more phenolic hydroxyl groups in one molecule, such as bisphenol A, bisphenol F, bisphenol S, a novolac type phenolic resin, poly-p-hydroxystyrene, a condensation product of naphthol and an aldehyde, or a condensation product of dihydroxynaphthalene and an aldehyde, with an alkylene oxide, such as ethylene oxide or propylene oxide, with an unsaturated group-containing monocarboxylic acid, such as (meth)acrylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride;
(5) A carboxyl group-containing photosensitive resin obtained by reacting a compound having two or more phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the reaction product obtained with an unsaturated group-containing monocarboxylic acid, and reacting the resulting reaction product with a polybasic acid anhydride;
(6) A photosensitive urethane resin having a terminal carboxyl group, which is obtained by reacting an acid anhydride with the terminal of a urethane resin obtained by polyaddition reaction of a diisocyanate compound, such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate, with a diol compound, such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol A alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group or an alcoholic hydroxyl group;
(7) A carboxyl group-containing photosensitive urethane resin having a terminal (meth)acrylation, which is obtained by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as a hydroxyalkyl (meth)acrylate, during the synthesis of a carboxyl group-containing urethane resin by a polyaddition reaction between a diisocyanate, a carboxyl group-containing dialcohol compound such as dimethylolpropionic acid or dimethylolbutyric acid, and a diol compound;
(8) A carboxyl group-containing photosensitive urethane resin having terminal (meth)acrylation, which is obtained by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reactant of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of a carboxyl group-containing urethane resin by polyaddition reaction of a diisocyanate, a carboxyl group-containing dialcohol compound, and a diol compound;
(9) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional oxetane resin with a dicarboxylic acid such as adipic acid, phthalic acid, or hexahydrophthalic acid, and adding a dibasic acid anhydride to the resulting primary hydroxyl group to obtain a carboxyl group-containing polyester resin, to which a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule, such as glycidyl (meth)acrylate or α-methylglycidyl (meth)acrylate, is further added.
(10) A carboxyl group-containing photosensitive resin obtained by adding a compound having a cyclic ether group and a (meth)acryloyl group in one molecule to any one of the carboxyl group-containing photosensitive resins (1) to (9) described above.
(11) A carboxyl group-containing photosensitive resin obtained by reacting a compound having a cyclic ether group and a (meth)acryloyl group in one molecule, such as 3,4-epoxycyclohexyl methacrylate, with a carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, a lower alkyl (meth)acrylate, or isobutylene. Note that (meth)acrylate here is a general term for acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions hereinafter.

The weight-average molecular weight of the photocurable compound described above varies depending on the resin skeleton, but is generally preferably 2,000 to 200,000. A weight-average molecular weight of 2,000 or more can improve tack-free performance and resolution. Furthermore, the change in state of the coating surface over time is moderated, and adhesion to the base can be further improved. Furthermore, a weight-average molecular weight of 200,000 or less can improve developability and storage stability. A more preferred weight-average molecular weight is 4,000 to 150,000, and even more preferably 5,000 to 100,000. The weight-average molecular weight can be measured by gel permeation chromatography (GPC) (polystyrene standard).

When the composition also contains a thermal crosslinking agent, which will be described later, the amount of the photocurable compound is preferably 50 to 90 parts by mass, calculated as solid content, when the total amount of the photocurable compound and the thermal crosslinking agent is 100 parts by mass. By setting the amount of the photocurable compound within the above range, a stronger hollow structure can be formed. In addition, the change in state of the coating surface over time becomes appropriate, and adhesion to the base can be further improved.

[Thermal cross-linking material]
By adding a thermal crosslinking agent, it is expected that the heat resistance of the photosensitive film will be improved. The thermal crosslinking agent can be used alone or in combination of two or more. Any known thermal crosslinking agent can be used. For example, known thermosetting components such as amino resins such as melamine resins, benzoguanamine resins, melamine derivatives, and benzoguanamine derivatives, isocyanate compounds, blocked isocyanate compounds, cyclocarbonate compounds, epoxy compounds, oxetane compounds, episulfide resins, bismaleimide, carbodiimide resins, melamine resins, urea resins, polyimide resins, and novolac resins such as phenol novolac and cresol novolac can be used. Among these, from the viewpoint of adhesion between the cured product of the photosensitive composition and the substrate, epoxy resins, melamine resins, and urea resins are preferred, and epoxy resins are more preferred.

When the composition also contains the above-mentioned photocurable compound, the amount of the thermal crosslinking agent is preferably 10 to 40 parts by mass, calculated as solid content, when the total amount of the photocurable compound and the thermal crosslinking agent is 100 parts by mass. By setting the amount of the thermal crosslinking agent within the above range, a stronger hollow structure can be formed. In addition, by setting the amount of the thermal crosslinking agent to 40 parts by mass or less, the proportion of the photocurable compound increases, thereby further improving the resolution.

When an epoxy resin or the like is used as the thermal crosslinking agent, a curing agent for curing the epoxy resin may be further included. Examples of curing agents include amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, and polymers containing these functional groups, and multiple types of these may be used as necessary.

[Photopolymerization initiator]
Specific examples of the photopolymerization initiator include bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-triphenylphosphine oxide, and bis-(2,6-dimethoxybenzoyl)-1-naphthylphosphine oxide. bisacylphosphine oxides such as bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide and bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphine acid methyl ester, 2-methylbenzoyldiphenylphosphine monoacylphosphine oxides such as phenyl(2,4,6-trimethylbenzoyl)phosphinate, isopropyl pivaloylphenylphosphinate, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl] benzoins such as benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bichlorobenzophenone, 4,4'-biphenyl ... Benzophenones such as diethylaminobenzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl)-1-[4 -(4-morpholinyl)phenyl]-1-butanone, N,N-dimethylaminoacetophenone and other acetophenones; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone and other thioxanthones; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone anthraquinones such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate and p-dimethylbenzoic acid ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-( oxime esters such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrol-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, and the like.

When the composition contains the above-mentioned photocurable compound, the amount of the photopolymerization initiator is preferably 0.1 to 10 parts by mass, calculated as solid content, per 100 parts by mass of the photocurable compound. By setting the amount of the photopolymerization initiator in the above range, the resolution is further improved.

A photoinitiator assistant or sensitizer may be used in combination with the above-mentioned photopolymerization initiator. Examples of the photoinitiator assistant or sensitizer include benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. These compounds may be used as photopolymerization initiators in some cases, but are preferably used in combination with a photopolymerization initiator. In addition, the photoinitiator assistant or sensitizer may be used alone or in combination of two or more types.

Note that these photopolymerization initiators, photoinitiator assistants, and sensitizers absorb specific wavelengths, and therefore in some cases may have low sensitivity and function as ultraviolet absorbers. However, these are not used solely for the purpose of improving the sensitivity of the composition. If necessary, they can be made to absorb light of specific wavelengths, increasing the photoreactivity of the surface and improving the precision of the shape after exposure and development.

[Filler]
By blending a filler in the photosensitive composition, the hardness and heat resistance of the coating film can be increased, and the change in the surface morphology of the photosensitive film over time can be adjusted. As such a filler, a known inorganic or organic filler can be used, but an inorganic filler is preferable. Examples of inorganic fillers include barium sulfate, silica, mica, hydrotalcite, talc, metal oxides, and metal hydroxides such as aluminum hydroxide. Among these, silica and mica are preferable. Examples of silica include spherical silica and amorphous silica.

If necessary, other resins than those mentioned above, thermal radical generators, polymerization inhibitors, adhesion aids, organic solvents, etc. may be added to the photosensitive composition.

For example, by blending other resins, it is possible to improve heat resistance. Examples of other resins include polyimide, polyoxazole and their precursors, novolac resins such as phenol novolac and cresol novolac, polyamideimide, polyamide, phenoxy resin, polyethersulfone, etc. These may be used alone or in combination of two or more.

The polyimide resin may also be made alkali-soluble. Specifically, it has alkali-soluble groups such as carboxyl groups and acid anhydride groups in addition to imide groups. Conventional methods can be used to introduce alkali-soluble groups. For example, a resin obtained by reacting a carboxylic anhydride component with at least one of an amine component and an isocyanate component can be used. Imidization can be performed by thermal imidization or chemical imidization, or these can be used in combination to produce the resin.

In addition, by adding a thermal radical generator, the photocurable compound can be cured at a low temperature in a short time. Examples of thermal radical generators include peroxides and azo compounds.

Polymerization inhibitors include hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, and phenothiazine. Adhesion aids include silane coupling agents such as gamma-glycidoxysilane, aminosilane, and gamma-ureidosilane.

The photosensitive film can be formed by applying the above-mentioned photosensitive composition to one side of a support film and drying it. Taking into consideration the coatability of the photosensitive composition, the photosensitive composition is diluted with an organic solvent to adjust the viscosity to an appropriate level, and then coated to a uniform thickness on one side of the support film using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, bar coater, roll coater, comma coater, slit die coater, spin coater, or the like, and the organic solvent is evaporated by drying to obtain a tack-free coating film. There is no particular restriction on the coating film thickness, but the thickness after drying is generally appropriately selected in the range of 0.5 to 500 μm. From the viewpoint of using the composition as a material for forming the walls and lids of a hollow structure, it is preferable that the thickness be in the range of 1 to 300 μm.

The organic solvents that can be used are not particularly limited, but examples include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum-based solvents, etc. More specifically, ketones such as methyl ethyl ketone (MEK) and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, diethylene glycol monoethyl ether acetate, and dipropylene glycol. Esters such as methyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha; and others such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and γ-butyrolactone. Such organic solvents may be used alone or as a mixture of two or more.

The organic solvent can be evaporated and dried using a hot air circulation drying oven, IR oven, hot plate, convection oven, etc. (a method using a heat source of air heating method using steam to bring hot air in the dryer into countercurrent contact, or a method spraying it onto the support from a nozzle). The evaporation drying conditions are appropriately selected from the range of 60 to 120°C for a temperature of 1 to 60 minutes.

[Protective film]
In the photosensitive film laminate of the present invention, a protective film is provided on the side of the photosensitive film opposite the support film for the purposes of preventing adhesion of dust and the like to the surface of the above-mentioned photosensitive film and improving handleability, and further for the purposes of adjusting the arithmetic mean surface roughness Ra of the photosensitive film surface.

As the protective film, for example, polyester film, polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc. can be used, but polypropylene film is particularly preferable. It is also preferable to select a material such that the adhesive strength between the protective film and the photosensitive film is smaller than the adhesive strength between the protective film and the photosensitive film. In addition, in order to make it easier to peel off the protective film when using the photosensitive film laminate, the surface of the protective film that comes into contact with the photosensitive film may be subjected to the above-mentioned release treatment.

The thickness of the protective film is not particularly limited, but is generally selected from the range of 10 to 200 μm depending on the application.

In the present invention, it is preferable to use a protective film having an arithmetic mean surface roughness Ra' of 0.10 μm or more on the surface side of the protective film that contacts the photosensitive film. It is more preferable to use a protective film having an arithmetic mean surface roughness Ry' of 1.00 μm or more on the surface side of the protective film that contacts the photosensitive film. By using a protective film having such a surface form, it becomes easier to form a photosensitive film having an arithmetic mean surface roughness Ra of 0.10 μm or more, and even easier to form a photosensitive film having an arithmetic mean surface roughness Ry of 1.00 μm or more. The arithmetic mean surface roughness Ra' of the protective film is more preferably 0.15 μm or more, and even more preferably 0.20 μm or more. When an upper limit is set, it is preferably 1.00 μm or less, more preferably 0.80 μm or less, and even more preferably 0.60 μm or less.

The maximum height Ry' of the protective film on the surface side in contact with the photosensitive film is more preferably 1.20 μm or more, and even more preferably 1.40 μm or more. When an upper limit is set, it is preferably 5.00 μm or less, more preferably 4.00 μm or less, and even more preferably 3.00 μm or less. Here, the meanings of the arithmetic mean surface roughness Ra' and the maximum height Ry' and the specific measurement methods thereof are explained in the above-mentioned [Photosensitive film]. Note that the arithmetic mean surface roughness Ra' of the protective film and the arithmetic mean surface roughness Ra of the photosensitive film, and the maximum height Ry' of the protective film and the maximum height Ry of the photosensitive film do not necessarily coincide with each other, but by appropriate adjustment, the arithmetic mean surface roughness Ra and the maximum height Ry of the photosensitive film can be set within the specific range as described above.

The method of adjusting a protective film having the above-mentioned arithmetic mean surface roughness Ra' and maximum height Ry' is not particularly limited. For example, when a filler is added to the resin of the protective film, the particle size or amount of the filler added can be adjusted. However, the surface of the protective film can be shaped to a desired form by blasting the surface, or by subjecting the surface to hairline processing, matte coating, chemical etching, or the like.

<Cured Product>
A cured product is formed using the photosensitive film laminate of the present invention. As an example of such a cured product, a method for forming a hollow structure having a wall portion and a lid portion using the photosensitive film laminate of the present invention will be described.

[Method of forming wall portion]
First, a wall portion is formed using a photosensitive film laminate. Specifically, a desired wall portion can be formed through a lamination process in which a protective film is peeled off from the photosensitive film laminate and the photosensitive film is laminated on an adherend such as a substrate, an exposure process in which a predetermined portion of the photosensitive film is irradiated with light through a mask to photocure the exposed portion, a development process in which a developer is used to remove the portion of the photosensitive film other than the photocure portion, and a main curing process in which the photocure portion of the photosensitive film is cured by light or heat to form a cured product. Each process will be described below.

In the lamination process, the protective film is peeled off from the photosensitive film laminate, and the exposed photosensitive film surface is laminated on the substrate. The lamination can be performed by adhesion by thermocompression or the like. Examples of the substrate that is the adherend include a silicon wafer, a glass substrate, a ceramic substrate, an aluminum-based substrate, a stainless steel substrate, a glass epoxy substrate, a polyester substrate, and a polyimide substrate. Methods of thermocompression include heat pressing, roll lamination, vacuum roll lamination, vacuum pressing, and diaphragm vacuum lamination. The thermocompression temperature is preferably 20 to 150°C, more preferably 35 to 100°C, and even more preferably 40 to 85°C, from the viewpoints of adhesion to the substrate, embeddability, and maintaining good resolution without curing of the photosensitive composition during thermocompression. The lamination pressure is preferably 0.005 to 10 MPa, and more preferably 0.005 to 3 MPa.

Next, an exposure process is carried out. There are negative and positive types of exposure, but the negative type is preferred. In the case of the negative type, the photosensitive film laminate laminated on the substrate is irradiated with light through a negative mask having a desired pattern that will become the shape of the wall portion, and the exposed portion of the photosensitive film is photocured. Here, examples of active light used for exposure include ultraviolet light, visible light, electron beams, X-rays, etc. Among these, ultraviolet light and visible light are particularly preferred. In addition, mask exposure using the i-line (365 nm), h-line (405 nm), and g-line (436 nm) of an ultra-high pressure mercury lamp through a photomask is preferred. In addition, a method of directly drawing the photosensitive film without a mask using a laser with a wavelength of 405 nm can also be mentioned. In this process, the support film constituting the photosensitive film laminate may be peeled off before exposure or after exposure. In addition, before exposure, the support film may be peeled off or not peeled off, and a heat treatment may be performed at a temperature of 40 ° C to 150 ° C for 5 seconds to 60 minutes using an oven or a hot plate at a temperature of 40 ° C to 150 ° C. After exposure, the support film may be peeled off or not, and the film may be heat-treated in an oven or on a hot plate at a temperature of 40 to 150°C for 5 seconds to 60 minutes.

Next, the areas of the photosensitive film that have not been photocured (unexposed areas) are removed using an organic solvent-based or alkaline aqueous solution-based developer to form a wall pattern.

As the developer, organic solvents such as N-methylpyrrolidone, ethanol, cyclohexanone, cyclopentanone, propylene glycol methyl ether acetate, γ-butyrolactone, triethylene glycol dimethyl ether, methyl amyl ketone (2-heptanone), and butyl acetate can be used. In addition, alkaline aqueous solutions such as sodium carbonate, sodium hydroxide, potassium hydroxide, sodium silicate, ammonia, ethylamine, diethylamine, triethylamine, triethanolamine, and tetramethylammonium hydroxide (TMAH) can be used. Among these, in terms of development speed, it is preferable to use propylene glycol methyl ether acetate in the case of solvent development. On the other hand, in the case of alkaline development, sodium carbonate, sodium hydroxide, and tetramethylammonium hydroxide (TMAH) are preferable.

Development methods include spraying the photosensitive film with developer, immersing the film in developer, or exposing the film to ultrasound while immersed.

After development, it is preferable to rinse the photosensitive film with water, alcohol such as methanol, ethanol, or isopropyl alcohol, or n-butyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether acetate, etc., as necessary. Rinsing methods include spraying the developer onto the photosensitive film surface, immersing the film in the developer, or applying ultrasonic waves while immersing the film in the developer.

Next, the photocured portions (exposed portions) of the photosensitive film are cured by light or heat to form walls. When curing after development is performed by heat, it is preferable to select a temperature and gradually increase the temperature for 1 to 2 hours. The heat curing temperature is appropriately selected from the range of 120 to 400°C, and the time is appropriately selected from the range of 60 to 120 minutes. The temperature may be fixed at a constant temperature or may be increased in stages. When curing, it is preferable to heat the film in an inert gas such as nitrogen or argon. The final heating temperature is preferably 150 to 350°C. Photocuring may be performed before or after heat curing, or instead of heat curing.

The thickness of the photosensitive film for forming the wall is preferably 1 to 3,000 μm, more preferably 5 to 1,000 μm, even more preferably 10 to 500 μm, particularly preferably 20 to 200 μm, and most preferably 20 to 100 μm. If the thickness of the photosensitive film is 1 μm or more, the shape of the wall is easily maintained, and large deformation is unlikely to occur even under high temperature and high pressure conditions during molding. Furthermore, if the thickness is 3,000 μm or less, the light transmittance of the photosensitive film during exposure is unlikely to be hindered. The thickness of the wall may be increased by repeating the lamination process of overlapping the photosensitive film. Furthermore, the final thickness of the wall formed through the curing process is also preferably 1 to 3,000 μm, more preferably 5 to 500 μm, and even more preferably 10 to 200 μm.

[Formation of the lid]
The wall portion made of the cured product of the photosensitive film formed by the above-mentioned forming method has a sufficient film thickness, and a hollow structure can be formed by covering the upper end of the wall portion with a ceramic substrate, a Si substrate, a glass substrate, a metal substrate, etc. as a lid, but the lid portion may be formed using a photosensitive film laminate. The method of forming the lid portion using a photosensitive film laminate will be described below.

A photosensitive film laminate from which the protective film has been peeled off is laminated on the upper end of the wall portion formed as described above, exposed to light, and developed as necessary, to harden the photocured photosensitive film to form a lid portion, thereby forming a hollow structure. When forming a lid portion using a photosensitive film laminate, it is not necessarily necessary to go through a development process, but for example, when manufacturing multiple hollow structure devices simultaneously in a batch, it is possible to expose only the size equivalent to the lid portion of the hollow device through a mask, and then develop the unexposed portion around it to separate it into individual pieces.

The lamination, exposure, development and curing of the photosensitive film laminate can be performed in the same manner as in the formation of the wall portion described above. Here, the adhesion during lamination of the laminate forming the wall portion and the lid portion can be performed by thermocompression. Examples of thermocompression methods include heat pressing, roll lamination, vacuum roll lamination, vacuum pressing, and diaphragm type vacuum lamination, among which roll lamination is preferred. The thermocompression temperature is preferably 20°C or higher from the viewpoint of adhesion to the adherend and embeddability. In addition, from the viewpoint of preventing the photosensitive resin component from curing during thermocompression, which advances the resolution of the pattern formation during exposure and development, the thermocompression temperature is preferably 150°C or lower. That is, the thermocompression temperature is preferably 20 to 150°C from the viewpoint of adhesion to the substrate, embeddability, and from the viewpoint of maintaining good resolution without the curing of the photosensitive composition during thermocompression, 35 to 100°C is more preferred, and 40 to 85°C is even more preferred. Additionally, the lamination pressure is preferably 0.005 to 10 MPa, and more preferably 0.005 to 3 MPa.

The support film constituting the photosensitive film laminate may be peeled off before exposure, after exposure, or after the photosensitive film is cured. However, peeling after exposure or peeling after curing is preferred from the viewpoint of stability, since the cured photosensitive film that becomes the lid is supported only by the wall. Also, before exposure, the support film may be peeled off or not, and a heat treatment may be performed for 5 seconds to 60 minutes at a temperature of 40 to 150°C using an oven or a hot plate. Also, after exposure, the support film may be peeled off or not, and a heat treatment may be performed for 5 seconds to 60 minutes at a temperature of 40 to 150°C using an oven or a hot plate. Furthermore, development and curing may be performed on the wall and lid at the same time. The tensile modulus of elasticity of the cured film that forms the lid is preferably 2.0 GPa or more.

The thickness of the photosensitive film for forming the lid is preferably 1 to 3,000 μm, more preferably 5 to 1,000 μm, even more preferably 10 to 500 μm, particularly preferably 20 to 200 μm, and most preferably 20 to 100 μm. The final thickness of the lid formed through the curing process is preferably 10 μm to 3,000 μm. If the thickness of the lid is 10 μm or more, the shape of the hollow structure is easily maintained, and large deformation is unlikely to occur even under high temperature and high pressure conditions during molding. Furthermore, if the thickness is 3,000 μm or less, the light transmittance of the photosensitive film during exposure is unlikely to be impaired. The thickness of the lid may be increased by repeating the lamination process of overlapping the photosensitive films.

In the present invention, the walls can be formed without using the photosensitive film laminate of the present invention, and only the lid can be formed using the photosensitive film laminate of the present invention. However, if both the wall pattern and the lid are made of the photosensitive film laminate of the present invention, the adhesion between the two is superior and peeling of plating, etc. in the vicinity of the hollow structure can be suppressed.

According to the present invention, in electronic components having a hollow structure such as SAW filters, the walls and lids are formed using the photosensitive film laminate of the present invention, thereby preventing peeling of plating and the like in the vicinity of the hollow structure. In addition, the inside of the hollow structure is moisture-proofed by the walls and lids, and the hollow structure is maintained even at high temperatures, so that it is applicable to electronic components that require a hollow structure such as SAW filters, CMOS/CCD sensors, and MEMS, and is useful for miniaturizing, reducing the height, and improving the functionality of electronic components. The photosensitive film laminate of the present invention is particularly suitable for forming the walls or lids of the hollow structure of SAW filters, and is particularly suitable in that it can provide highly reliable electronic components in which peeling of plating and the like in the vicinity of the hollow structure is prevented. In addition, the present invention may also be used for printed wiring board applications such as solder resist, plating resist, etching resist, and interlayer insulating material.

<SAW Filter and Its Manufacturing Method>
A method for forming a hollow structure having walls and a lid using the photosensitive film laminate of the present invention has been described. As an example of an electronic component having a hollow structure, a surface acoustic wave (SAW) filter and a method for manufacturing the same will be described below.

First, the protective film is peeled off from the photosensitive film laminate of the present invention, and the photosensitive film surface is laminated on a substrate on which a comb-shaped electrode is formed. The photosensitive film laminate can be laminated using a method similar to that described in the method for forming the wall portion described above.

Next, after laminating the photosensitive film laminate, a predetermined portion of the photosensitive film is irradiated with light through a negative mask having a desired pattern as necessary, and the exposed portion is photocured. The exposure can be performed using a method similar to that described in the method for forming the wall portion described above.

Next, the desired pattern is formed by removing the non-exposed areas of the photosensitive film using a developer, and then the exposed areas of the photosensitive film are cured with light or heat to form walls made of a cured product. Note that the steps of exposure, development, and curing can be performed using the same methods as those for forming the walls described above.

As described below, when the photosensitive film laminate of the present invention is used to form a lid portion of a hollow structure of a SAW filter, the wall portion may be formed by a method other than the method using the photosensitive film laminate of the present invention.

A lid is provided on the upper end of the wall portion formed as described above to form a hollow structure. Here, the lid portion can be formed by peeling off the protective film from the photosensitive film laminate of the present invention, attaching the photosensitive film surface to the upper end of the wall portion, and then exposing, developing, and curing the lid portion. The lid portion and the wall portion can be bonded together, for example, by thermocompression bonding using a roll laminator.

The lid may be made of a material other than the photosensitive film laminate of the present invention, such as a known permanent resist or a sealing substrate such as ceramic. However, it is preferable that the lid is made of a material that has excellent resistance to moist heat and low water absorption. In this case, at least the wall formed using the photosensitive film laminate of the present invention is used as the wall for forming the hollow structure of the SAW filter.

After the walls and lid are formed as described above, plating may be formed and metal balls may be mounted, etc., to establish electrical connections between the electrodes and the conductors wired inside the substrate and on the opposite surface of the electrodes.

When forming the wall, a hole for forming an internal conductor may be formed inside the wall by exposure and development. Then, a photosensitive film laminated on a support film is laminated on the wall and exposed through a mask. The mask is shielded so that only the portion corresponding to the diameter of the hole for forming the internal conductor does not transmit light, and the other portions form a photocured lid. The unexposed portion of the lid is patterned by developing and then performing a desmearing process or the like to completely penetrate the hole inside the wall that was previously formed. A laser may also be used to pattern the lid. Known lasers such as YAG lasers, carbon dioxide lasers, and excimer lasers can be used as the laser. Exposure or laser irradiation can be appropriately selected and used depending on the thickness of the wall, the shape of the internal conductor formed inside the wall, and the shape of the wiring pattern on the surface of the lid.

Furthermore, an internal conductor is formed in the hole formed inside the wall and the lid by plating or the like, and wiring is formed on the surface of the lid. In the present invention, the internal conductor can be formed in the hole formed inside the wall and the lid not only by plating, but also by a conductor filling method using a resin paste containing a metal paste or metal powder. Through these steps, the conductor wired to the comb-shaped electrode on the substrate is electrically connected to the wiring conductor formed on the surface of the lid. Finally, a metal ball is mounted on the surface of the lid by reflow or the like, and a SAW filter, which is an electronic component with a hollow structure, can be obtained.

Furthermore, the SAW filter may be sealed with a sealing material. Sealing with a sealing material is generally performed in the following steps, but is not limited to these. First, the SAW filter is set in a molding die. Next, a solid sealing material tablet is set in the pot of the molding machine. The sealing material is melted at a die temperature of 150-180°C and poured into the die under pressure (molding). Finally, pressure is applied for 30-120 seconds to thermally harden the sealing material, after which the die is opened and the molded product is removed, completing the sealing of the SAW filter.

Usually, sealing with a sealant is performed before the metal balls are mounted, and after sealing, the metal balls are mounted by reflow on the surface opposite the sealed surface of the substrate. However, sealing with a sealant may be performed after the metal balls are mounted. It is possible to manufacture not only one SAW filter sealed with a sealant, but also multiple SAW filters. In this case, multiple SAW filters formed on one substrate are sealed with a sealant, and then cut into individual pieces to obtain the SAW filters. Specifically, first, multiple SAW filters are produced on one substrate, and wall and cover portions are formed using the photosensitive film laminate of the present invention or the like. The SAW filters are then sealed together with a sealant, and cut into individual pieces by a method such as cutting to obtain the SAW filters.

As described above, in the manufacturing process of a SAW filter, a hollow structure having walls and a lid can be formed using the photosensitive film laminate of the present invention. As described above, the photosensitive film laminate of the present invention has a change in surface morphology over time within a specific range, so that a SAW filter can be realized in which peeling of plating, etc. in the vicinity of the hollow structure is suppressed. In addition, the inside of the hollow structure is isolated from the surroundings by the walls and lid formed using the photosensitive film laminate of the present invention, making it moisture-proof, so that corrosion of the aluminum electrodes can be suppressed. In addition, the cured product of the photosensitive film has a high elastic modulus at high temperatures, so there is an advantage in that the hollow structure can be maintained even at the temperature and pressure during sealing resin molding.

The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" are all based on mass unless otherwise specified, except for the percentage related to relative humidity. In addition, the work in the following examples was carried out at room temperature (23°C), at a relative humidity of 42%, and under a yellow lamp.

<Synthesis Example 1>
<Synthesis of Carboxyl Group-Containing Resin>
In a 2 L flask equipped with a stirrer and a reflux condenser, 367.0 parts of a bifunctional bisphenol-A type epoxy resin (RE-310S manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent: 183.5 g/equivalent) as an epoxy compound having two or more epoxy groups in a molecule, 144.1 parts of acrylic acid (molecular weight: 72.06) as a monocarboxylic acid compound having an ethylenically unsaturated group, 1.02 parts of hydroquinone monomethyl ether as a thermal polymerization inhibitor, and 1.53 parts of triphenylphosphine as a reaction catalyst were charged and reacted at a temperature of 98° C. until the acid value of the reaction liquid became 0.5 mgKOH/g or less, to obtain an epoxy carboxylate compound (theoretical molecular weight: 511.1).
Next, 445.93 parts of carbitol acetate as a reaction solvent, 0.70 parts of 2-methylhydroquinone as a thermal polymerization inhibitor, and 118.8 parts of dimethylolpropionic acid (molecular weight: 134.1) as a diol compound having a carboxyl group were added to the reaction solution, and the temperature was raised to 60°C. 209.6 parts of isophorone diisocyanate (molecular weight: 222.29) as a diisocyanate compound were gradually dropped into the solution so that the reaction temperature did not exceed 65°C. After the dropwise addition was completed, the temperature was raised to 80°C, and the reaction was carried out for 6 hours until the absorption at around 2250 cm ^-1 disappeared by infrared absorption spectroscopy. 36.7 parts of succinic anhydride (molecular weight: 100.1) and 43.0 parts of carbitol acetate were added to the solution as a polybasic acid anhydride. After the addition, the temperature was raised to 95° C. and the mixture was reacted for 6 hours to obtain a carboxyl-containing photosensitive resin varnish 1 containing 65% by weight of a carboxyl-containing polyester urethane resin having a weight average molecular weight of 10,000. The acid value was measured to be 66.61 mg KOH/g (solid acid value: 102.5 mg KOH/g). The weight average molecular weight was measured according to a standard method using gel permeation chromatography (GPC) (polystyrene standard).

<Synthesis Example 2>
<Synthesis of Carboxyl Group-Containing Resin>
In an autoclave equipped with a thermometer, a nitrogen introduction device/alkylene oxide introduction device, and a stirrer, 119.4 g of novolac cresol resin (Aica Kogyo Co., Ltd., SHONOL CRG951, OH equivalent: 119.4), 1.19 g of potassium hydroxide, and 119.4 g of toluene were charged, and the system was replaced with nitrogen while stirring, and the temperature was raised. Next, 63.8 g of propylene oxide was gradually dropped, and the reaction was carried out for 16 hours at 125 to 132 ° C and 0 to 4.8 kg / cm ^2. Thereafter, the reaction solution was cooled to room temperature, and 1.56 g of 89% phosphoric acid was added and mixed to neutralize the potassium hydroxide, and a propylene oxide reaction solution of novolac cresol resin with a nonvolatile content of 62.1% and a hydroxyl value of 182.2 g / eq. was obtained. The resulting novolak cresol resin had an average of 1.08 moles of alkylene oxide added per equivalent of the phenolic hydroxyl group.
293.0 g of the alkylene oxide reaction solution of the obtained novolac cresol resin, 43.2 g of acrylic acid, 11.53 g of methanesulfonic acid, 0.18 g of methyl hydroquinone, and 252.9 g of toluene were charged into a reactor equipped with a stirrer, a thermometer, and an air blowing tube, and the mixture was reacted at 110° C. for 12 hours while blowing air at a rate of 10 ml/min and stirring. The water generated by the reaction was distilled as an azeotropic mixture with toluene, and 12.6 g of water was distilled. Then, the mixture was cooled to room temperature, and the obtained reaction solution was neutralized with 35.35 g of 15% aqueous sodium hydroxide solution, and then washed with water. Then, the toluene was distilled off while replacing it with 118.1 g of diethylene glycol monoethyl ether acetate in an evaporator, and a novolac acrylate resin solution was obtained. Next, 332.5 g of the obtained novolac type acrylate resin solution and 1.22 g of triphenylphosphine were charged into a reactor equipped with a stirrer, a thermometer, and an air inlet tube, and 62.3 g of tetrahydrophthalic anhydride was gradually added while blowing air at a rate of 10 ml/min and stirring. The mixture was reacted at 95 to 101° C. for 6 hours to obtain a carboxyl group-containing photosensitive resin varnish 2 with an acid value of 88 mg KOH/g and a non-volatile content of 71%.

<Synthesis Example 3>
<Synthesis of Carboxyl Group-Containing Resin>
220 parts (1 equivalent) of cresol novolac epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EOCN-104S, epoxy equivalent 220 g/eq), 140.1 parts of carbitol acetate, and 60.3 parts of solvent naphtha were charged into a flask, heated to 90° C., stirred, and dissolved.
The resulting solution was cooled to 60° C., and 72 parts (1 mole) of acrylic acid, 0.5 parts of methylhydroquinone, and 2 parts of triphenylphosphine were added, heated to 100° C., and reacted for about 12 hours to obtain a reaction product with an acid value of 0.2 mgKOH/g. 80.6 parts (0.53 moles) of tetrahydrophthalic anhydride were added thereto, heated to 90° C., and reacted for about 6 hours to obtain a carboxyl group-containing photosensitive resin varnish 3 with an acid value of 85 mgKOH/g in solid content and a solid content of 64.9%.

<Synthesis Example 4>
<Synthesis of Carboxyl Group-Containing Resin>
190 parts of phenol novolac epoxy resin EPPN-201 (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent = 190) was placed in a four-neck flask equipped with a stirrer and a reflux condenser, 184 parts of carbitol acetate was added, and the mixture was dissolved by heating. Next, 0.46 parts of methyl hydroquinone as a polymerization inhibitor and 1.38 parts of triphenylphosphine as a reaction catalyst were added. This mixture was heated to 95-105 ° C., and 72 parts (1 equivalent) of acrylic acid were gradually added dropwise and reacted for 16 hours. The resulting reaction product (hydroxyl group: 1 equivalent) was cooled to 80-90 ° C., 50 parts (0.5 equivalent) of succinic anhydride were added, reacted for 8 hours, and then cooled and taken out. In this way, a carboxyl group-containing photosensitive resin varnish 4 with a nonvolatile content of 65%, an acid value of the solid matter of 89 mgKOH/g, and a solid content of 65.0% was obtained.

<Preparation of Photosensitive Composition>
The components were mixed in the amounts (parts by mass) shown in Table 1 below and kneaded uniformly to prepare photosensitive compositions 1 to 4. In Table 1, *1 to *22 represent the following components.
*1 Methylated melamine resin, manufactured by Sanwa Chemical Co., Ltd. *2 Fluorene skeleton-containing epoxy resin, manufactured by Osaka Gas Chemicals Co., Ltd. *3 Bisphenol A type epoxy resin (manufactured by DIC Corporation)
*4 Biphenyl aralkyl type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.)
*5 Phenol novolac epoxy resin (DIC Corporation)
*6 Dicyclopentadiene type epoxy resin (DIC Corporation)
*7 Synthesis Example 1 (amount blended is solid content)
*8 Synthesis Example 2 (mixture amount is solid content)
*9 Synthesis Example 3 (amount blended is solid content)
*10 Synthesis Example 4 (amount blended is solid content)
*11 Alkaline-soluble photosensitive resin with an amide-imide structure (20% solids, manufactured by Nippon Kodo Paper Co., Ltd.)
*12 Dipentaerythritol acrylate, manufactured by Kyoeisha Chemical Co., Ltd. *13 ε-caprolactone-modified dipentaerythritol acrylate, manufactured by Kyoeisha Chemical Co., Ltd. *14 Tricyclodecane dimethanol diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd. *15 Oxime ester photopolymerization initiator (ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(0-acetyloxime)), manufactured by BASF Japan Ltd. *16 Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by IGM Resins)
*17 2-Ethyl-4-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.)
*18 Spherical silica, manufactured by Admatechs Co., Ltd. *19 Spherical silica particles with an average particle size of 100 nm *20 C.I. Pigment Blue 15:3
*21 C. I. Pigment Yellow 147
*22 Paliogen Red K3580 (manufactured by BASF Japan)

<Preparation of protective film>
Preparation Example 1
A polypropylene resin pellet having a weight average molecular weight (Mw) of 3.0×10 ⁵ , a molecular weight distribution (Mw/Mn) of 5.0, and an isotactic component fraction of 95.0% was fed to an extruder, melted at a resin temperature of 250° C., extruded through a T-die, and wound around a metal drum whose surface temperature was kept at 150° C. to produce a film, thereby producing a cast raw sheet having a thickness of about 225 μm. The unstretched cast raw sheet was then stretched 5 times in the machine direction at a temperature of 120° C., immediately cooled to room temperature, and then stretched 10 times in the transverse direction at a temperature of 160° C. in a tenter to obtain a biaxially stretched polypropylene film 1 having a thickness of 12 μm. This biaxially stretched polypropylene film 1 is referred to as a protective film 1.

Preparation Example 2
A polypropylene resin pellet having a weight average molecular weight (Mw) of 3.1×10 ⁵ , a molecular weight distribution (Mw/Mn) of 5.5, and an isotactic component fraction of 93.0% was fed to an extruder, melted at a resin temperature of 250° C., extruded through a T-die, and wound around a metal drum whose surface temperature was kept at 150° C. to produce a film, thereby producing a cast raw sheet having a thickness of about 225 μm. Subsequently, this unstretched cast raw sheet was stretched 5 times in the machine direction at a temperature of 200° C., immediately cooled to room temperature, and then stretched 10 times in the transverse direction at a temperature of 160° C. in a tenter to obtain a biaxially stretched polypropylene film 2 having a thickness of 15 μm. This biaxially stretched polypropylene film 2 is referred to as a protective film 2.

Preparation Example 3
A polypropylene resin pellet having a weight average molecular weight (Mw) of 3.0×10 ⁵ , a molecular weight distribution (Mw/Mn) of 5.0, and an isotactic component fraction of 95.0% was fed to an extruder, melted at a resin temperature of 250° C., extruded through a T-die, and wound around a metal drum whose surface temperature was kept at 100° C. to produce a film, thereby producing a cast raw sheet having a thickness of about 225 μm. The unstretched cast raw sheet was then stretched 5 times in the machine direction at a temperature of 120° C., immediately cooled to room temperature, and then stretched 10 times in the transverse direction at a temperature of 160° C. in a tenter to obtain a biaxially stretched polypropylene film 3 having a thickness of 12 μm. This biaxially stretched polypropylene film 3 is used as a protective film 3.

<Support film>
As the support film 1, a polyethylene terephthalate film (Lumirror T60 manufactured by Toray Industries, Inc.) was used.

<Preparation of Photosensitive Film Laminate>
Example 1
The arithmetic mean surface roughness Ra' and maximum height Ry' of protective film 1 obtained as described above were measured as follows, and the Ra' was 0.18 μm and the maximum height Ry' was 1.28 μm.

A shape measuring laser microscope (VK-X100, Keyence Corporation) was used to measure the arithmetic mean surface roughness Ra' and Ry'. After starting the shape measuring laser microscope (VK-X100) main body (control unit) and the VK observation application (VK-H1VX, Keyence Corporation), the protective film to be measured (the surface in contact with the photosensitive film is the upper side) was placed on the xy stage. The lens revolver of the microscope unit (VK-X110, Keyence Corporation) was turned to select a 10x objective lens, and the focus and brightness were roughly adjusted in the image observation mode of the VK observation application (VK-H1VX). The xy stage was operated to adjust the part of the sample surface to be measured so that it was at the center of the screen. The 10x objective lens was replaced with a 50x magnification lens, and the focus was adjusted to the sample surface using the autofocus function of the image observation mode of the VK observation application (VK-H1VX). Select the simple mode in the shape measurement tab of the VK observation application (VK-H1VX), press the measurement start button to measure the surface shape of the sample and obtain a surface image file. Launch the VK analysis application (VK-H1XA, manufactured by Keyence Corporation) to display the obtained surface image file, and then perform tilt correction.

The observation measurement range (horizontal) in measuring the surface shape of the sample was 270 μm. After displaying the line roughness window and selecting JIS B0601-1994 in the parameter setting area, a horizontal line was selected from the measurement line button, and the horizontal line was displayed at any location within the surface image. The OK button was then pressed to obtain the numerical values of the arithmetic mean surface roughness Ra' and maximum height Ry'. Furthermore, horizontal lines were displayed at four different locations within the surface image, and the numerical values of the arithmetic mean surface roughness Ra' and maximum height Ry' at each location were obtained. The averages of the five numerical values obtained were calculated, and these were taken as the arithmetic mean surface roughness Ra' value and maximum height Ry' value of the sample surface. The measurements were performed at room temperature (23°C) and a relative humidity of 42%.

Next, 700 parts of the photosensitive composition 1 obtained as described above was diluted by adding 300 parts of methyl ethyl ketone, and the mixture was stirred with a stirrer for 15 minutes to obtain a coating liquid. This coating liquid was uniformly applied onto the support film 1 using a slit die coater, and dried at a temperature of 80°C for 15 minutes to produce a photosensitive film 1 having a thickness of 25 μm after drying. Next, the protective film 1 was laminated onto the photosensitive film 1 using a roll laminator so that the measurement surface of the arithmetic mean surface roughness Ra' and maximum height Ry' of the protective film 1 was in contact with the surface of the photosensitive film 1, thereby producing a photosensitive film laminate 1 (photosensitive film thickness 25 μm) consisting of three layers of support film/photosensitive film/protective film. The lamination conditions using the roll laminator were appropriately adjusted within the range of a roll temperature of 40 to 60°C and a roll pressure of 0.2 to 0.4 MPa.

<Preparation of Test Substrate>
A test substrate was prepared using the photosensitive film laminate 1 obtained as described above. The procedure for preparing the test substrate will be described with reference to the drawings.
First, the protective film was peeled off from the photosensitive film laminate 1 at an angle of 90° to the other two layers (support film/photosensitive film) at a speed of 2.5 seconds/cm to expose the photosensitive film, and the exposed surface of the photosensitive film was attached to the surface of a prepared silicon wafer, followed by heat lamination using a roll laminator to bring the silicon wafer and the photosensitive film into close contact. The lamination conditions using the roll laminator were a roll temperature of 60° C. and a roll pressure of 0.25 MPa.

Next, from the support film that is in contact with the photosensitive film,
(i) a negative mask having an opening pattern with a lattice size of 150 μm square and 50 μm square (see FIG. 1 ), or (ii) a negative mask having an opening pattern with a lattice size of 150 μm square and 100 μm square (not shown)
For each of the Examples and Comparative Examples, the photosensitive film was exposed to light using a metal halide lamp with the combination of pattern opening and exposure dose shown in Table 2, and then the support film was peeled off to expose the photosensitive film.

Thereafter, the exposed surface of the exposed photosensitive film was immersed in propylene glycol monomethyl ether acetate (PMA) at 23°C for 1 minute for Examples 1-3 and Comparative Examples 1-2, developed in a 1 wt% _{Na2CO3 aqueous} solution at 30°C, 2 MPa for 60 seconds for Example 4, and developed in a ₁ wt% _Na2CO3 aqueous solution at 30°C, 2 MPa for 300 seconds for Example 5. After development, each test substrate was thoroughly washed with water to ensure that no developer remained. The pH of the 1 wt% _{Na2CO3 aqueous} solution was confirmed to be 11.6.

Next, each test substrate was heated at 120° C. for 30 minutes to harden the photosensitive film, and the following was added to the periphery of the lattice-shaped 150 μm square openings:
(i) a cured film pattern corresponding to a 150 μm wide wall having a 50 μm square pattern opening in the center (see FIG. 2 ), or (ii) a cured pattern corresponding to a 300 μm wide wall having a 100 μm square pattern opening in the center (not shown).
obtained.

The protective film was then peeled off from the photosensitive film laminate 1 to expose the photosensitive film, and the exposed surface of the photosensitive film was attached to the cured film pattern corresponding to the wall portion obtained above, followed by heat lamination. The lamination was performed by heating at 80°C for 5 minutes while applying a weight of 1.0 kg to the photosensitive film.

Next, from the support film side of the photosensitive film laminate laminated onto the cured film pattern corresponding to the wall portion,
(i) a negative mask having an opening pattern with a lattice size of 50 μm square (see FIG. 3), or (ii) a negative mask having an opening pattern with a lattice size of 100 μm square (not shown).
For each of the examples and comparative examples, the photosensitive film was exposed to light using a metal halide lamp with the combination of pattern opening and exposure dose shown in Table 2, and then the support film was peeled off to expose the photosensitive film.
(i) a 50 μm square pattern opening of the wall portion and a pattern opening of a lattice size of 50 μm square of the negative mask are overlapped (see FIG. 3 ), or (ii) a 100 μm square pattern opening of the wall portion and a pattern opening of a lattice size of 100 μm square of the negative mask are overlapped (not shown),
After that, the exposed surface of the exposed photosensitive film was immersed in propylene glycol monomethyl ether acetate (PMA) at 23°C for 1 minute for Examples 1 to 3 and Comparative Examples 1 and 2, and developed in a 1 wt% _{Na2CO3 aqueous} solution at 30°C, 2 MPa for 60 seconds for Example 4, and developed in a 1 wt% _{Na2CO3 aqueous} solution at 30°C, 2 MPa for 300 seconds for Example 5. After development, each test substrate was thoroughly washed with water to ensure that no developer remained.

Next, each test substrate was heated at 200° C. for 60 minutes to cure the photosensitive film, and a cured film pattern corresponding to the lid was formed, thereby producing a test substrate having a hollow structure consisting of a wall portion and a lid portion. The obtained test substrate did not have a comb-shaped electrode inside, but the upper end of the wall portion was covered with the lid portion, and the joint between the lid portion and the wall portion had a
(i) a 50 μm square pattern opening (see FIG. 4 ), or (ii) a 100 μm square pattern opening (not shown).
The hollow structure was formed.

Example 2
A test substrate was prepared in the same manner as in Example 1, except that photosensitive composition 2 was used instead of photosensitive composition 1 and protective film 2 was used instead of protective film 1. The arithmetic mean surface roughness Ra' and maximum height Ry' of protective film 2 were measured in the same manner as above, and Ra' was 0.46 μm and maximum height Ry' was 1.37 μm. Protective film 2 was in a roll form, and the inner surface of the roll was measured.

Example 3
A test substrate was prepared in the same manner as in Example 1, except that Protective Film 2 was used instead of Protective Film 1 in Example 1.

Example 4
A test substrate was prepared in the same manner as in Example 2, except that development with propylene glycol monomethyl ether acetate (PMA) was replaced by development with a 1 wt % Na ₂ CO ₃ aqueous solution at 30° C. and 2 MPa for 60 seconds.

Example 5
A test substrate was prepared in the same manner as in Example 4, except that Photosensitive Composition 3 was used instead of Photosensitive Composition 2, and development was performed in a 1 wt % Na ₂ CO ₃ aqueous solution at 30° C. and 2 MPa for 300 seconds.

Comparative Example 1
A test substrate was prepared in the same manner as in Example 2, except that Photosensitive Composition 4 was used instead of Photosensitive Composition 2 in Example 2.

Comparative Example 2
A test substrate was prepared in the same manner as in Example 1, except that protective film 3 was used instead of protective film 1 in Example 1. The arithmetic mean surface roughness Ra' and maximum height Ry' of protective film 3 were measured in the same manner as above, and Ra' was 0.07 μm and maximum height Ry' was 0.98 μm. Protective film 3 was in a roll form, and the inner surface of the roll was measured.

<Measurement of arithmetic mean surface roughness Ra and maximum height Ry>
Each of the photosensitive film laminates (35 mm × 20 mm) used in Examples 1 to 5 and Comparative Examples 1 and 2 was attached to the surface of a clean glass substrate (76 mm × 26 mm × 1.1 mmt) using double-sided tape (KZ-12, manufactured by Nitoms Corporation) so that the glass substrate and the support film side of the photosensitive film were in contact with each other, thereby closely adhering the glass substrate and the photosensitive film laminate.
Thereafter, the protective film of the photosensitive film laminate was peeled off at an angle of 90° to the glass substrate at a speed of 2.5 sec/cm to expose the photosensitive film. The arithmetic mean surface roughness Ra1 and maximum height Ry1 of the exposed photosensitive film surface immediately after the protective film was peeled off (after 1 minute had elapsed) were measured within 5 minutes after the protective film was peeled off. The measurements of Ra1 and Ry1 were performed as follows.

The "arithmetic mean surface roughness Ra" of the exposed photosensitive film surface was measured in the same manner as above, using the same device as in the measurement of the arithmetic mean surface roughness Ra' of the protective film surface, except that the sample was a substrate with exposed photosensitive film attached (with the exposed photosensitive film surface at the top) instead of a protective film. The "maximum height Ry" of the exposed photosensitive film surface was also measured in the same manner as above, using the same device as in the measurement of the maximum height Ry' of the support film surface, except that the sample was a substrate with exposed photosensitive film attached (with the exposed photosensitive film surface at the top) instead of a protective film. The "arithmetic mean surface roughness Ra1" and "maximum height Ry1" of each measured photosensitive film surface were as shown in Table 2.

In addition, each measurement sample was left under a yellow lamp for 180 minutes in the measurement environment (room temperature (23°C), relative humidity 42%) with the photosensitive film surface exposed by peeling off the protective film, and then the arithmetic mean surface roughness Ra and maximum height Ry of the exposed photosensitive film surface were measured in the same manner as above. The "arithmetic mean surface roughness Ra2" and "maximum height Ry2" of each measured photosensitive film surface were as shown in Table 2.

<Plating adhesion evaluation>
Electroless copper plating was carried out on each of the test substrates prepared as described above in Examples 1 to 5 and Comparative Examples 1 and 2. The plating conditions were as follows.
Electroless copper plating solution: Melplate CU-390 (Meltex Inc.)
・Plating solution temperature: 80°C
Plating time: 1 hour Plating thickness: 2.0 μm
pH: 13.0 (room temperature)
After the plating process, each test substrate on which the electroless plating film was formed was washed with pure water at room temperature for 5 minutes and then dried at 80° C. The cross-sectional portion of the boundary between the wall and the electroless plating film of each obtained test substrate was observed with an optical microscope and an electron microscope. The evaluation criteria were as follows:
⊚: No gaps were generated and there was no problem with adhesion. ◯: Some gaps were generated, but there was no problem with adhesion. ×: Gaps were generated and there was a problem with adhesion. The evaluation results were as shown in Table 2 below.

As is clear from the results in Table 2, Test Substrates 1 to 5 (Examples 1 to 5), in which a hollow structure was formed using a photosensitive film laminate having an arithmetic mean surface roughness Ra1 of the photosensitive film surface of 0.1 μm or more and an Ra2/Ra1 of 0.40 or more and less than 1.00, had high adhesion to the plating on the wall and lid portions, and electronic components having a high-quality hollow structure could be obtained.
On the other hand, test substrate 7 (Comparative Example 2), in which a hollow structure was formed using a photosensitive film laminate in which the arithmetic mean surface roughness Ra1 of the photosensitive film surface was less than 0.1 μm, was found to have insufficient adhesion to the plating of the wall and lid portions, even though Ra2/Ra1 was 0.40 or more and less than 1.00.
Furthermore, it can be seen that test substrate 6 (Comparative Example 1), in which a hollow structure was formed using a photosensitive film laminate in which the arithmetic mean surface roughness Ra1 of the photosensitive film surface was 0.1 μm or more, but the Ra2/Ra1 was not within the range of 0.40 or more and less than 1.00, also had insufficient adhesion to the plating of the wall and lid portions.

Claims (7)

A photosensitive film laminate including, in order, a support film, a photosensitive film formed from a photosensitive composition, and a protective film,
the photosensitive composition includes an alkali developable resin and an inorganic filler in an amount of more than 0 parts by mass and not more than 70 parts by mass relative to 100 parts by mass of the alkali developable resin in terms of solid content,
The protective film was peeled off from the photosensitive film laminate in a direction perpendicular to the surface of the photosensitive film at a speed of 2.5 seconds/cm to expose the surface of the photosensitive film. The surface of the photosensitive film was then left for 1 minute in an environment of 23° C. and a relative humidity of 42%, after which the arithmetic average surface roughness of the surface of the photosensitive film was determined as Ra1.
The protective film was peeled off from the photosensitive film laminate in a direction perpendicular to the surface of the photosensitive film at a speed of 2.5 seconds/cm to expose the surface of the photosensitive film. After leaving the surface of the photosensitive film for 180 minutes in an environment of 23° C. and a relative humidity of 42%, the arithmetic average surface roughness of the surface of the photosensitive film was determined as Ra2.
In this case, the following formula:
Ra1≧0.10 μm and 0.40≦Ra2/Ra1<1.00
The filling,
The protective film was peeled off from the photosensitive film laminate in a direction perpendicular to the surface of the photosensitive film at a speed of 2.5 seconds/cm to expose the surface of the photosensitive film. After leaving the surface of the photosensitive film for 1 minute in an environment of 23° C. and a relative humidity of 42%, the maximum height of the surface of the photosensitive film was determined as Ry1.
The protective film is peeled off from the photosensitive film laminate in a direction perpendicular to the surface of the photosensitive film at a speed of 2.5 seconds/cm to expose the surface of the photosensitive film. After leaving the surface of the photosensitive film for 180 minutes in an environment of 23° C. and a relative humidity of 42%, the maximum height of the surface of the photosensitive film is Ry2.
In this case, the following formula:
Ry1≧1.00 μm and 0.30≦Ry2/Ry1<1.00
The filling,
The arithmetic average surface roughness Ra' of the surface of the protective film on the side in contact with the photosensitive film is 0.10 μm or more;
The maximum height Ry' of the surface of the protective film on the side in contact with the photosensitive film is 1.00 μm or more.
A photosensitive film laminate comprising: The photosensitive film laminate according to claim 1, wherein the photosensitive composition contains a photocurable compound. The photosensitive film laminate according to claim 1 or 2 , wherein the photosensitive composition further comprises a photopolymerization initiator. The photosensitive film laminate according to any one of claims 1 to 3 , which is used to form a lid or wall that constitutes a hollow structure in an electronic component having a hollow structure. A cured product obtained by curing the photosensitive film of the photosensitive film laminate according to any one of claims 1 to 4 . An electronic part comprising the cured product according to claim 5 . The electronic component according to claim 6 , which has a hollow structure consisting of a wall portion and a lid portion, and either or both of the wall portion and the lid portion are made of the cured material.