JP2000047389A - Photosensitive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photosensitive film which is excellent in shelf stability and work efficiency and can be laminated on the surface of a substrate by an atmospheric pressure laminating method in a good yield while suppressing the occurrence of air voids by using a specified urethane compd. as a photopolymerizable unsatd. compd. and forming a protective coat contg. a small number of fish eyes. SOLUTION: A photosensitive resin layer is formed on a support film in 5-30 μm thickness using a photosensitive resin compsn. contg. 5-93 wt.% carboxyl-contg. linear polymer, 5-93 wt.% photopolymerizable unsatd. compd. of the formula and 0.01-30 wt.% photopolymn. initiator and a protective coat contg. <=5 fish eyes of >=80 μm diameter per 1 m2 is stuck on the photosensitive resin layer. In the formula, R1 and R4 are each H or methyl, R2 is a residue of formula II [where (m) is an integer of 2-25], R3 is a residue of formula III or the like (where n1 is an integer of 1-25) and W is a 2-20C divalent hydrocarbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photosensitive film suitably used for metal etching of a printed circuit board or a lead frame.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have become lighter, thinner and shorter, and the number of products in a small quantity has increased, lead frames and BGAs used for mounting IC chips on a substrate have also increased in pins and reduced in size. Printed circuit boards on which these semiconductor packages are mounted also require higher densities.

As a resist for forming such a pattern, a photosensitive film is generally used. The photosensitive film has a sandwich structure in which the photosensitive resin composition is coated on a transparent support film, dried, and a protective film is adhered to the photosensitive film. Then, exposure is performed through a mask film or the like. Next, the support film is peeled off, and the unexposed portions are dissolved or dispersed and removed with a developer to form a cured resist image on the substrate.

[0004] Processes for forming a circuit are roughly classified into two methods, an etching method and a plating method. Here, the etching method is a method in which a metal surface that is not covered with a cured resist formed after development is removed by etching, and then the resist is removed. On the other hand, with the plating method, after performing a plating process such as copper and solder on a metal surface that is not covered with a cured resist formed after development,
In this method, the resist is removed, and the metal surface covered with the resist is etched.

Also, with the increase in the number of pins and narrowing of lead frames and BGAs and the densification of printed circuit boards on which these semiconductor packages are mounted, photosensitive films tend to become thinner in view of resolution, adhesion and cost. It is in.

[0006] As the photosensitive film becomes thinner, the embeddability (followability) with respect to the unevenness on the surface of the substrate decreases, and the etching method causes chipping and disconnection of a circuit pattern, and the plating method causes a short circuit. Cause. Therefore, the photosensitive resin layer must be flowed by heat and pressure in order to obtain an embedding property for unevenness on the substrate surface during lamination.

On the other hand, a polyester film such as a PET (polyethylene terephthalate) film is used as a support film of the photosensitive film, and a polyolefin film such as a PE (polyethylene) film is used as a protective film. A polyolefin film usually used as a protective film is produced by hot-melting a raw material, kneading, extruding, biaxial stretching, a casting method or an inflation method. Generally, a protective film such as a polyolefin film contains undissolved and thermally degraded substances called fish eyes. The size of the fish eye is generally 10 μm to 1 mm in diameter (φ)
At a height of 1 to 50 μm from the film surface. The projections of the fish eyes are transferred to the photosensitive resin layer to form dents in the photosensitive resin layer, and air voids 6 as shown in FIG. 1 are formed on the substrate after lamination. That is, when the photosensitive film including the support film 1, the photosensitive resin layer 2, and the protective film 3 having the fish eyes 4 is peeled off and laminated on the substrate 5, air voids 6 are generated. This air void correlates with the thickness of the photosensitive resin layer, and is more likely to occur as the thickness of the photosensitive resin layer becomes smaller. In the subsequent steps of exposure and development resist image formation,
This may cause pattern breakage and disconnection. This phenomenon causes chipping and disconnection of the circuit pattern in the case of the etching method, and causes a short circuit in the case of the plating method.
Therefore, the photosensitive resin layer must flow by heat and pressure in order to prevent air from being entrained into the photosensitive resin layer portion that is concave due to fish eyes during lamination.

As a countermeasure against such a phenomenon, a method of lowering the viscosity of the photosensitive resin layer and improving the resin flow during lamination can be considered. In this case, a method called edge fusion from the end of the photosensitive film is called an edge fusion. There is a problem that the exudation of the conductive resin layer occurs and the laminating property deteriorates.

Also, it is necessary to use a film having a smooth surface as a peelable film at the time of lamination.
No. 402 discloses this. However, the above publication is characterized in that a photosensitive resin composition is applied on a release film at the time of lamination, dried to form a photosensitive resin layer, and a support film is further laminated thereon. In this case, it is necessary to select a material that does not change its dimensions due to heat when the photosensitive resin composition is applied and dried, and the material is limited.

A vacuum laminating method is useful as disclosed in JP-B-53-31670, JP-A-51-63702, JP-A-1-314144 and the like. As compared with the normal pressure lamination method used in the above, there are problems such as that the size of the apparatus is large and that the inside of the chamber for laminating is vacuum, so that dust is easily generated.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a normal pressure lamination method in which a photosensitive film can be laminated on a substrate surface having a metal surface with a reduced number of air voids and with a good yield, and Another object of the present invention is to provide a photosensitive film excellent in storage stability and workability of the photosensitive film.

Another object of the present invention is to provide a photosensitive film which exhibits the effects of the above-described invention and is excellent in laminating properties.

[0013]

As a result of intensive studies to solve the above problems, a protective film having a small number of fish eyes is used, and a propylene glycol residue is contained as a photopolymerizable unsaturated compound. By using a specific urethane compound, it has been found that air voids generated during lamination are reduced, and the ability to follow irregularities on the substrate surface is good, and the present invention has been achieved.

That is, the present invention relates to a photosensitive film in which a photosensitive resin layer (B) containing a photosensitive resin composition is formed on a support film (A), and a protective film (C) is further laminated thereon. The number of fish eyes having a diameter of 80 μm or more contained in the protective film (C) is 5 / m
² or less, and the photosensitive resin composition is (a) 5 to 93% by weight of a linear polymer containing a carboxyl group, (b)
5 to 93% by weight of a photopolymerizable unsaturated compound containing one or more compounds selected from the compounds represented by the following general formula (I) and (c) a photopolymerization initiator of 0.01 to 30
The present invention provides a photosensitive film containing the photosensitive resin composition containing the photosensitive resin composition in an amount of 5 to 30 μm by weight.

[0015]

Embedded image (Where R ¹ and R ⁴ are a hydrogen atom or a methyl group;
² is a residue represented by the following formula (I-1);
It is an integer up to 25. R ³ is a residue represented by the following formula (I-2) or (I-3), and n1 is 1 to 25
And n2 is an integer from 1 to 12.
Further, the ratio n2 / m of n2 to m is 3 or less,
W is a divalent hydrocarbon group having 2 to 20 carbon atoms. )

[0016]

Embedded image

[0017]

Embedded image

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The support film (A) in the present invention is, for example, Tetron Film G manufactured by Teijin Limited.
Examples include polyester films such as S series and Mylar film D series manufactured by DuPont. Preferably, a polyethylene terephthalate film is used. The thickness of the support film is preferably from 12 to 25 μm, and if the thickness is less than 12 μm, the mechanical strength is reduced. Therefore, a problem such as breakage of the support film during coating tends to occur, while the thickness is more than 25 μm. In this case, the resolution tends to decrease and the price tends to increase.

The linear polymer (a) contained in the photosensitive resin composition according to the present invention has a carboxyl group content of preferably from 100 to 600 in terms of acid equivalent, and more preferably from 3 to 3 in terms of acid equivalent.
00 to 600. Here, the acid equivalent refers to the weight of a polymer having one equivalent of a carboxyl group therein. The carboxyl group in the polymer is necessary to have developability and releasability with respect to an aqueous alkali solution, but when the acid equivalent exceeds 600, the developability and releasability tend to decrease, and
If it is less than 0, the chemical resistance and the compatibility with the coating solvent or other components such as (b) a photopolymerizable unsaturated compound tend to decrease. The weight average molecular weight of the linear polymer (a) is preferably from 20,000 to 500,000, more preferably from 50,000 to 500,000.
200,000. When the weight average molecular weight (measured in terms of standard polystyrene using GPC) exceeds 500,000,
Developability, peelability and resolution tend to decrease, and when it is less than 20,000, mechanical strength tends to deteriorate.

The linear polymer is preferably obtained by copolymerizing two or more monomers. Monomers are classified into two types. The first monomer is a carboxylic acid or an acid anhydride having one polymerizable unsaturated group in the molecule. For example, (meth) acrylic acid (which represents methacrylic acid and acrylic acid; the same applies hereinafter), fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, maleic acid half ester and the like. The second monomer is selected so as to maintain various properties such as the developability of the photosensitive resin layer, the resistance in the etching and plating steps, and the flexibility of the cured film. For example,
There are alkyl (meth) acrylates such as methyl (meth) acrylate (which represents methacrylate and acrylate; the same applies hereinafter), butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Further, there are esters of vinyl alcohol such as vinyl acetate, and styrene or a polymerizable styrene derivative. The linear polymer can also be obtained by polymerizing only the carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule.

The amount of the linear polymer (a) contained in the photosensitive resin composition must be in the range of 5 to 93% by weight, preferably 30 to 70% by weight. When the amount of the linear polymer is less than 5% by weight, the photocured product is brittle and the peelability is poor, and when it exceeds 93% by weight, the sensitivity becomes insufficient.

(B) of the photosensitive resin composition of the present invention
The photopolymerizable unsaturated compound as a component contains the compound represented by the general formula (I) as an essential component. General formula (I)
When the compound represented by is used as a photopolymerizable unsaturated compound, the viscosity of the photosensitive resin layer (B) is reduced during lamination, the embedding property for unevenness on the substrate surface is improved, and the fisheye in the protective film reduces It is possible to suppress air entrapment in the photosensitive resin layer portion where the dent has occurred.

In the photosensitive resin composition of the present invention, the photopolymerizable unsaturated compound of the component (b) is 5-93.
% By weight, but this ratio is more preferably in the range of 20 to 60% by weight. 5% by weight of photopolymerizable unsaturated compound
If it is less than 90%, the sensitivity is insufficient. If it exceeds 93% by weight, the photocured product is brittle and the peelability is poor.

The proportion of the compound represented by the formula (I) in the photopolymerizable unsaturated compound of the component (b) is from 40 to 1
00% by weight is preferred. If it is less than 40% by weight, the above-mentioned properties of the resist tend to be impaired. As the photopolymerizable unsaturated compound, a compound other than the compound represented by the general formula (I) can be used in combination.

In the photopolymerizable unsaturated compound represented by the general formula (I), R ¹ and R ⁴ are a hydrogen atom or a methyl group, R ² is a repeating propylene oxide, and m is 2 to 25. , And preferably 3 to
It is an integer up to 15. When m is less than 2, the cured film becomes brittle, and when it exceeds 25, the sensitivity is lowered. R ³ may be repeating propylene oxide or repeating ethylene oxide. n1 is an integer from 1 to 25;
Preferably, an integer of 1 to 15 and n2 is an integer of 1 to 12. Also, n2 / m is 3 or less, preferably 1.5 or less. When n2 / m exceeds 3, the chemical resistance decreases.
W is a divalent hydrocarbon group having 2 to 20 carbon atoms, may be linear or branched, may be alicyclic or aromatic, Particularly, a long-chain aliphatic group, alicyclic group or aromatic group is preferred. Specific examples include an alkylene group, a substituted alkylene group, a cycloalkylene group, a mixed group having the alkylene group and the cycloalkylene group, an arylene group, and the like.

The photopolymerizable unsaturated compound of the compound represented by the general formula (I) may be a compound of the following general formula (II-1), a compound of the formula (II-2) and a compound of the formula (II), or ( It is obtained by reacting the compound of II-1), the compound of (II-3) and the compound of (II).

[0027]

Embedded image (W is a divalent hydrocarbon group having 2 to 20 carbon atoms.)

[0028]

Embedded image (Where R ¹ and R ⁴ are a hydrogen atom or a methyl group, m is 2 to
An integer up to 25, n1 is an integer from 1 to 25, m and n
1 may be the same. n2 is an integer of 1 to 12. When employing the compound of (II-3), it is necessary to select (II-1) and (II-2) so that n2 / m is 3 or less.

Preferred examples of the compounds (II-1) and (II-2) include 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polypropylene glycol methacrylate and polypropylene glycol acrylate. (For example, manufactured by NOF Corporation, Blemmer PP-1000 (m and n1 =
5-6), PP-500 (m and n1 = 9), PP-3
00 (m and n1 = 12)) Preferred examples of the compound (II-3) include hydroxyethyl acrylate, hydroxyethyl methacrylate, polyethylene glycol monoacrylate, and polyethylene glycol monomethacrylate. (For example, manufactured by NOF Corporation, Blemmer PE-90 (n2 =
2), PE-200 (n2 = 4 to 5)) Preferred examples of the compound (II) include hexamethylene diisocyanate, tolylene diisocyanate, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2,4-trimethyl Hexamethylene diisocyanate and the like.

The photopolymerizable unsaturated compound other than the compound represented by the formula (I) used in the component (b) is not particularly limited, and a general photopolymerizable unsaturated compound may be used. Can be. Specific examples include 2-hydroxy-3-phenoxypropyl acrylate, phenoxytetraethylene glycol acrylate, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), and polypropylene glycol di (meth) acrylate (ethylene Having 2 to 14 groups), dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, bisphenol A polyoxyethylene diacrylate, and a glycidyl group-containing compound to which an α, β-unsaturated carboxylic acid is added. Compounds (trimethylolpropane glycidyl ether triacrylate, bisphenol A glycidyl ether diacrylate, etc.), 2,2-bis (4-methacryloxypentaethoxyphenyl) propane, β- Dorokishiechiru -β'- acryloyloxyethyl phthalate.

The photosensitive resin composition of the present invention contains a photopolymerization initiator as an essential component. The photopolymerization initiator here is any known compound that is activated by various actinic rays, for example, ultraviolet rays, and starts polymerization.
For example, 2-ethylanthraquinone, 2-tert-butylanthraquinone, octamethylanthraquinone,
1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-chloroanthraquinone, 2
-Methylanthraquinone, 1,4-naphthoquinone, 9,
There are quinones such as 10-phenanthraquinone, 2-methyl-1,4-naphthoquinone, and 2,3-dimethylanthraquinone. Further, for example, there are aromatic ketones such as benzophenone, Michler's ketone (4,4'-bis (dimethylamino) benzophenone) and 4,4'-bis (diethylamino) benzophenone. Also for example benzoin,
Benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, methyl benzoin,
There are benzoin ethers such as ethyl benzoin. Also, a thioxanthone compound such as a combination of diethylthioxanthone and dimethylaminobenzoic acid may be used.
There is also a combination with a secondary amine compound. For example, 2-
(O-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-
(Fluorophenyl) -4,5-diphenylimidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer 2, such as the body
There are 4,5-triarylimidazole dimers. These are used alone or in combination of two or more.

(C) contained in the photosensitive resin composition
The amount of the component photopolymerization initiator is 0.01 to 30% by weight, preferably 0.05 to 10% by weight. If the amount of the photopolymerization initiator is less than 0.01% by weight, sufficient sensitivity cannot be obtained. On the other hand, when the content exceeds 30% by weight, the active ray absorption rate of the photosensitive resin layer increases, and the degree of curing at the bottom of the photosensitive resin layer becomes insufficient.

The photosensitive resin composition of the present invention may contain, if necessary, a plasticizer, a thermal polymerization inhibitor, a color former such as leuco crystal violet, tribromomethylphenylsulfone, a dye such as malachite green, a pigment, and a filler. Agents, adhesion-imparting agents, fragrances, imaging agents, and the like.

The photosensitive resin composition containing the above components (a), (b) and (c) is added with a solvent if necessary to form a solution, which is then put on a support film (A). The photosensitive resin layer (B) is formed by coating and drying. Next, a photosensitive film is obtained by laminating a protective film (C) on the photosensitive resin layer.

The solvent is not particularly limited, and known solvents can be used, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, chloroform, methylene chloride, toluene, methanol, ethanol And the like. These can be used alone or 2
Used in combination of more than one type.

The thickness of the photosensitive resin layer (B) is 5 to 30 μm.
m. When the thickness is less than 5 μm, wrinkles are likely to occur during lamination, and when the thickness is more than 30 μm, the resolution deteriorates. Preferred thickness is 10 to 25 μm
It is.

The viscosity of the photosensitive resin layer (B) (30)
C) is preferably 15 to 50 MPa · s, and 2
More preferably, it is 5 to 40 MPa · s. If the viscosity is less than 15 MPa · s (30 ° C.), resin bleeding called edge fusion tends to occur. If the viscosity is more than 40 MPa · s (30 ° C.), the resin fluidity decreases, and the photosensitive resin The layers tend to be brittle. The viscosity can be measured by using the relational expression (I) for Newtonian fluid, plotting t against 1 / Z ⁴ , and calculating the slope.

[0038]

(Equation 1) η: viscosity (Pa · s) F: force applied in the thickness direction (N) V: volume of test piece (m ³ ) Z: thickness (m) t: time (second) In addition, these measurements were performed using a TMA device. Can be measured using

The number of fish eyes having a diameter (φ) of 80 μm or more contained in the protective film (C) used in the present invention must be 5 / m ² or less. Here, the fish eye refers to a material in which undissolved and degraded materials of the material are incorporated into the film when the material is hot-melted, kneaded, extruded and stretched, cast, or inflationed to produce a film.

The diameter of the fish eye varies depending on the material, but is about 10 μm to 1 mm, and the height from the film surface is about 1 to 50 μm. Here, the method of measuring the size of the fish eye can be measured by, for example, an optical microscope, a contact surface roughness meter, a non-contact surface roughness meter, or a scanning electron microscope. In addition. The diameter (φ) of the fish eye means the maximum diameter.

The surface roughness of the protective film is as follows:
The center line average roughness Ra is preferably from 0.005 to 0.3 μm, more preferably from 0.01 to 0.1 μm. The surface roughness can be measured using a contact type surface roughness meter.

As described above, the protective film preferably used in the present invention having a good fish-eye level is, for example, a film which is produced by removing foreign substances of the raw material resin, filtering the raw material resin after hot melting, etc. It can be manufactured by changing the manufacturing method.

As commercially available products, Alphan E-200S and E-200H manufactured by Oji Paper Co., Ltd., PP-type PT manufactured by Shin-Etsu Film Co., Ltd., and Torayfan BO-240 manufactured by Toray Industries, Inc.
0, YR12 type and other polypropylene films, etc., but not limited thereto.

The protective film (C) has a thickness of 15 to 50 μm.
m is preferable. When the thickness is less than 15 μm, the production tends to be difficult, and when the thickness is more than 50 μm, the price tends to be high.

The adhesive strength between the photosensitive resin layer (B) containing the photosensitive resin composition and the support film (Α) is different from that of the photosensitive resin layer (B) containing the photosensitive resin composition and the protective film (C). It is preferable that the adhesive strength is higher than the adhesive strength. The adhesive strength between the photosensitive resin layer (B) containing the photosensitive resin composition and the support film (A) is higher than the adhesive strength between the photosensitive resin layer (B) containing the photosensitive resin composition and the protective film (C). If it is small, the photosensitive resin layer may be transferred to the protective film when the protective film is removed during lamination.

[0046]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Production Example 1 2 liters of 4 equipped with a dropping funnel, thermometer and stirrer
Hexamethylene diisocyanate 168
g, 254 g of dry methyl ethyl ketone as a solvent, and 0.25 g of dibutyltin dilaurate as a catalyst, and with stirring, polypropylene glycol monomethacrylate (Blenmer PP-100 manufactured by NOF Corporation).
0) After dropping 850 g, the mixture was stirred for 10 hours. During this time, the internal temperature was adjusted so as not to exceed 50 ° C. The reaction product was analyzed by infrared absorption spectrum, and it was confirmed that the characteristic absorption of the isocyanate group near 2270 cm ^-1 had almost disappeared. This reaction product is designated as M-1.

Production Example 2 In the same flask as in Production Example 1, 174 g of tolylene diisocyanate (80% 2,4-form, 20% 2,6-form), 256 g of dry methyl ethyl ketone, and 0.25 g of dibutyltin dilaurate as a catalyst. 850 g of polypropylene glycol monomethacrylate (Blenmer PP-1000 manufactured by NOF CORPORATION) was added dropwise with stirring, followed by stirring for 10 hours. During this time, the internal temperature was adjusted so as not to exceed 50 ° C. The reaction product was analyzed by an infrared absorption spectrum, and it was confirmed that the characteristic absorption of the isocyanate group near 2270 cm ^-1 had almost disappeared. This reaction product is designated as M-2.

Production Example 3 168 g of hexamethylene diisocyanate, 190 g of dry methyl ethyl ketone, and 0.25 g of dibutyltin dilaurate as a catalyst were added to the same flask as in Production Example 1, and polypropylene glycol monomethacrylate (manufactured by NOF CORPORATION) 100
0) 430 g was added dropwise. Next, 140 g of 2-hydroxypropyl methacrylate was added dropwise, followed by stirring for 10 hours. During this time, the internal temperature was adjusted so as not to exceed 50 ° C. The reaction product was analyzed by infrared absorption spectrum, and 2270
It was confirmed that the characteristic absorption of the isocyanate group near cm ^-1 had almost disappeared. This reaction product is designated as M-3.

The starting compounds used in Production Examples 1 to 3 and the amounts added are shown in Table 1, and the chemical structures of the obtained reaction products are shown below.

[0051]

[Table 1] * 1: HMDI: hexamethylene diisocyanate * 2: TDI: tolylene diisocyanate * 3: PP-1000: polypropylene glycol monomethacrylate (Blenmer PP manufactured by NOF Corporation)
-1000) * 4: HPMA: 2-hydroxypropyl methacrylate

[0052]

Embedded image Examples 1 to 6 and Comparative Examples 1 to 5 The components (a), (b), (c) and other components shown in Table 2 were mixed to prepare a solution of a photosensitive resin composition.

[0053]

[Table 2] MMA: methyl methacrylate n-BA: normal butyl acrylate MAA: methacrylic acid BPE-500: 2,2-bis (4-methacryloxypentaethoxyphenyl) propane: Shin-Nakamura Chemical Co., Ltd. OE-A200: Nippon Shokubai Chemical Co., Ltd. The following compound (β-hydroxypropyl-β′-acryloyloxypropyl phthalate)

[0054]

Embedded image Next, the solution of the photosensitive resin composition was uniformly applied on a polyethylene terephthalate film having a thickness of 16 μm, and
It was dried with a hot air convection dryer at 00 ° C. for about 5 minutes, and each protective film shown in Table 3 was laminated to obtain a photosensitive film. The thickness of the dried photosensitive resin layer was 20 μm.

A test piece having a thickness of 1 mm and a diameter of 7 mm was prepared by laminating the photosensitive resin layers of the photosensitive film prepared above. Next, a TMA device (Thermal Ana)
lysis: Seiko Electronic Industry Co., Ltd., TMA / SS1
00), a load of 2 to 40 g was applied in the thickness direction of the test piece at 30 to 80 ° C., and the amount of change in thickness was measured. Then, t was plotted against 1 / Z ⁴ using the relational expression (I) for Newtonian fluid, and the viscosity was determined from the slope.

[0056]

(Equation 2) Microvoid Evaluation A copper alloy (O-7025, manufactured by Yamaha Orin Metal Co., Ltd.) having a thickness of 0.15 mmt and a thickness of 20 × 20 cm was immersed in a 3% by weight aqueous sodium hydroxide solution at 50 ° C. for 1 minute, and then 1% by volume hydrochloric acid. The substrate was immersed in an aqueous solution at 25 ° C. for 1 minute, then washed with water and dried. While removing the protective film of the photosensitive film on the obtained substrate, the roll temperature was 110 ° C., the pressure was 4 kg · f / cm ² , and the speed was 4 mm. : Laminated at 2 m / min. Next, the thus obtained substrate was set to 3 kW.
High pressure mercury lamp (HMW-201G, manufactured by Oak Manufacturing Co., Ltd.)
X), exposure was performed at 60 mJ / cm ² .

The number of air voids on the substrate after exposure is 100
The measurements were taken using a microscope at × magnification. In addition, the size and number of fish eyes of each protective film were measured using a microscope of 100 times.

Evaluation of conformability to unevenness A photosensitive film H-S930 (trade name, manufactured by Hitachi Chemical Co., Ltd., product name: MCL-E68, copper thickness: 35 μm, manufactured by Hitachi Chemical Co., Ltd.) was used on a 1.6 mm thick copper-clad laminate. : Photek) was laminated under the above conditions. Then, using a photomask having a line / space of 400/100 μm,
kW ultra-high pressure mercury lamp (manufactured by Oak Works, HMW-20
1GX) at 30 mJ / cm ² , and after removing the supporting film, a 1% by weight aqueous solution of sodium carbonate (30
C.) for about 30 seconds to remove unexposed areas. This substrate was treated with a 25% by weight aqueous solution of ammonium persulfate (30% by weight).
C.) for 6 minutes, washed with water, and then immersed in a 3% by weight aqueous sodium hydroxide solution (50 ° C.) for 1 minute to remove the cured resist film and prepare a scratched substrate. As a result of measuring the depth of the scratch using a contact surface roughness meter (Surfcoder SE-30D, manufactured by Kosaka Laboratory Co., Ltd.), the scratch depth was 6 μm.

While removing the protective film of the photosensitive film from the scratched substrate, the laminate was laminated at a roll temperature of 110 ° C., a pressure of 4 kg · f / cm ² and a speed of 2 m / min. At this time, the scratch on the substrate was parallel to the laminating roll. Then, the line / space is 100/10
A 0 μm photomask was set to be perpendicular to the scratches on the substrate, and exposed to 60 mJ / cm ² with a 3 kW ultra-high pressure mercury lamp (manufactured by Oak Manufacturing Co., Ltd., HMW-201GX) to remove the support film. Thereafter, a 1% by weight aqueous solution of sodium carbonate (30 ° C.) was sprayed for about 30 seconds to remove unexposed portions. Next, 45 Baume ferric chloride aqueous solution (5
(0 ° C.) for 100 seconds to etch the exposed copper and add 1% to a 3% by weight aqueous sodium hydroxide solution (50 ° C.).
Then, the cured resist film was removed.

When the photosensitive resin layer does not follow the scratches on the substrate, there is a gap between the resist and the substrate, so that the copper line dissolves the copper at the intersection of the resist and the scratches, and the copper dissolves. The copper line is not connected, resulting in a disconnection failure. The intersection of the resist and the scratch was observed using a microscope of 25 magnifications, and the disconnection and the ratio of missing 1/3 or more of the line (number of observed intersections: 250 locations) were evaluated. Is bad).

The results are summarized in Table 3.

[0062]

[Table 3] GS-16: manufactured by Teijin Limited, polyethylene terephthalate film E-200S: manufactured by Oji Paper Co., Ltd., polypropylene film NF-13: manufactured by Tamapoly, polyethylene film As is clear from Table 3, the examples are air void compared to the comparative examples. The number of occurrences is small, and excellent followability to irregularities on the substrate surface.

[0063]

As described above, the photosensitive film of the present invention has a small number of air voids and is excellent in following the surface irregularities of the substrate, so that chipping and disconnection defects are reduced. Therefore, it is extremely useful for improving the yield of metal etching of a printed circuit board or a lead frame.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating the generation of air voids.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support film 2 Photosensitive resin layer 3 Protective film 4 Fisheye 5 Substrate 6 Air void

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/06 H05K 3/06 J

Claims (3)

[Claims] 1. A photosensitive film comprising a photosensitive resin layer (B) containing a photosensitive resin composition formed on a support film (A) and a protective film (C) further laminated thereon. 80μ in diameter contained in film (C)
m or more, and the number of fish eyes is 5 / m ² or less, and the photosensitive resin composition is (a) 5 to 93% by weight of a linear polymer containing a carboxyl group, and (b) the following general formula (I) )
Containing 5 to 93% by weight of a photopolymerizable unsaturated compound containing one or more compounds selected from the compounds represented by the following, and (c) 0.01 to 30% by weight of a photopolymerization initiator,
When the thickness of the photosensitive resin layer (B) containing the photosensitive resin composition is 5
A photosensitive film having a thickness of about 30 μm. Embedded image (Where R ¹ and R ⁴ are a hydrogen atom or a methyl group;
² is a residue represented by the following formula (I-1);
It is an integer up to 25. R ³ is a residue represented by the following formula (I-2) or (I-3), and n1 is 1 to 25
And n2 is an integer from 1 to 12.
Further, the ratio n2 / m of n2 to m is 3 or less,
W is a divalent hydrocarbon group having 2 to 20 carbon atoms. ) Embedded image 2. The adhesive strength between the photosensitive resin layer (B) containing the photosensitive resin composition and the support film (A) is the same as that of the photosensitive resin layer (B) containing the photosensitive resin composition and the protective film (C).
The photosensitive film according to claim 1, which has an adhesive strength higher than that of the photosensitive film. 3. The photosensitive film according to claim 1, wherein the protective film (C) is a polypropylene film.