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WO2009084929A2 - A multilayer film for dry film resist - Google Patents

A multilayer film for dry film resist Download PDF

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Publication number
WO2009084929A2
WO2009084929A2 PCT/KR2008/007900 KR2008007900W WO2009084929A2 WO 2009084929 A2 WO2009084929 A2 WO 2009084929A2 KR 2008007900 W KR2008007900 W KR 2008007900W WO 2009084929 A2 WO2009084929 A2 WO 2009084929A2
Authority
WO
WIPO (PCT)
Prior art keywords
surface layer
adhesiveness
film
set forth
additive
Prior art date
Application number
PCT/KR2008/007900
Other languages
French (fr)
Other versions
WO2009084929A3 (en
Inventor
Gi Sang Song
Original Assignee
Kolon Industries, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kolon Industries, Inc. filed Critical Kolon Industries, Inc.
Priority to CN2008801235204A priority Critical patent/CN101911843B/en
Priority claimed from KR1020080138542A external-priority patent/KR101376477B1/en
Publication of WO2009084929A2 publication Critical patent/WO2009084929A2/en
Publication of WO2009084929A3 publication Critical patent/WO2009084929A3/en

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0073—Masks not provided for in groups H05K3/02 - H05K3/46, e.g. for photomechanical production of patterned surfaces
    • H05K3/0079—Masks not provided for in groups H05K3/02 - H05K3/46, e.g. for photomechanical production of patterned surfaces characterised by the method of application or removal of the mask
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
    • H05K2201/0203—Fillers and particles
    • H05K2201/0206—Materials
    • H05K2201/0209—Inorganic, non-metallic particles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
    • H05K2201/0203—Fillers and particles
    • H05K2201/0206—Materials
    • H05K2201/0212—Resin particles
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/06—Lamination
    • H05K2203/066—Transfer laminating of insulating material, e.g. resist as a whole layer, not as a pattern
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/12—Using specific substances
    • H05K2203/127—Lubricants, e.g. during drilling of holes

Definitions

  • the present invention relates to a multilayer film for a dry film resist used in fabrication of a printed circuit board, a lead frame and a ball grid array, and a dry film resist using the same.
  • a dry film resist which is also called as a dry film photoresist or a photosensitive film, has been used, since it has developed as a brand name 'RISTON' by Du Pont in 1968, in a lead frame used to mount a semiconductor integrated circuit or a ball grid array which is a large scale integrated circuit
  • LSI LSI package in which semispherical solder terminals are arranged in a two-dimensional array on a bask side of a printed circuit board (PCB) mounted with a bare chip to substitute the lead, and particularly used as an epochal processing technique material for forming a circuit on a PCB which is basically used to connect components in various electronic appliances.
  • PCB printed circuit board
  • a conventional dry film resist consists of three layers, i.e., a base film layer, a photosensitive layer and a protective cover film.
  • the base film layer of the dry film resist employs a transparent film.
  • a polyester based film such as polyethyleneterephthalate (PET) film is used with a thickness of about 25 jL/m.
  • the photosensitive layer is obtained by coating and drying a photosensitive resin composition on the base film, and is formed from a negative or positive photosensitive resin composition. Also, according to a developing manner, the photosensitive layer is known to an alkali-developing type in which an alkali aqueous solution is used to develop and an organic solvent-developing type in which an organic solvent is used to develop, and the alkali-developing type tends to be increasingly used as compared with the organic solvent- developing type having problems such as stability in operation process, environmental pollution and high production cost.
  • the photosensitive layer is prepared by coating and drying a photosensitive resin composition generally consisting of, though its composition may vary as required mechanical and chemical properties and processing condition, a photopolymerizable multifunctional monomer, a photoinitiator inducing the photopolymerization of the multifunctional monomer, a polymeric binder providing mechanical strength, tenting property and adhesiveness to the photosensitive layer and, according to an object, additional additives such as dyes, stabilizers, adhesion promoter and thermal polymerization inhibitor.
  • a polyolefin film such as a polyethylene film having good flexibility, chemical resistance and releasability is conventionally used.
  • the protective cover film is prepared by kneading and extruding thermally molten raw material and then biaxially stretching or casting the extrudate .
  • the reason of using the protective cover film in the dry film resist is because the protective cover film prevents a telescope (an original form of product is not maintained, while the foam comes out) from being generated when winding the dry film resist after a photosensitive polymer is coated on the base film and dried, raises the releasability between the photosensitive layer and the base film, and acts as a cover for protecting the photosensitive layer from foreign substances such as dust .
  • a gel containing non-molten substances and heated substances is formed in the polyolefin film and the gel is called as a fish- eye since a micro-protuberance like a fish' s eye is present in the film after the film is formed.
  • the fish-eye generally has a diameter of 30 to 600 ⁇ m and protuberated from the surface of the cover film to a height of 2 to 40 ⁇ m.
  • the photosensitive layer though it belongs to a solid, is not a hard solid of which shape is not deformed but has certain deformability .
  • the protuberated portion of the fish-eye of the protective cover film is transferred onto the photosensitive layer to thereby form a recess in the photosensitive layer.
  • the formed recess generates an air void between the photosensitive layer and a substrate because the protective cover film is removed and the photosensitive layer is pressed on a substrate with heating when the dry film resist is laminated on the substrate, and the air void causes poor pattern such as a chip or an open circuit when forming a wiring pattern according to subsequent exposure, development and etching processes.
  • Japanese Patent Publication Hll-153861 discloses a dry film resist employing a polyolefin cover film in which the number of fish-eyes with a major axis of greater than 80 ⁇ m is less than 5/m 2
  • Japanese Patent Publication 2003-342307 discloses a polyethylene film in which the number of fish-eyes with a major axis of 30 ⁇ m to 0.20 mm is less than 40/m 2 and the number of fish-eyes with a major axis of greater than 0.20 mm is less than 1.0/m 2 , and a method of preparing the same.
  • the production cost of the dry film resist employing the polyethylene with a low fish-eye density, which is hard to be prepared and generally high-priced, is raised.
  • An object of the present invention is to provide a multilayer film which enhances releasability between a photosensitive layer and a base film without using a protective cover film in a dry film resist, and a dry film resist using the same.
  • the present invention provides a multilayer film including a first surface layer and a second surface layer which opposes to the first surface layer, wherein an adhesiveness a of the first surface layer and an adhesiveness b of the second surface layer meet the following equation: [Equation 1] b > a.
  • the first surface layer contains 0.001 to 5 wt% of an additive and the second surface layer contains no additive or less than 0.5 wt% of an additive, and the adhesiveness a and b of the first surface layer and the second surface layer meet the following equation:
  • the present invention provides a functional film in which a functional layer is stacked on the second surface layer having a higher adhesiveness of the multilayer film as described above.
  • Example for the functional film may include a multilayer film, preferably a dry film resist in which a photosensitive layer is stacked on a multilayer polyester film.
  • the conventional dry film resist employs a protective cover film and therefore has a problem of a fish-eye.
  • the present invention provides the dry film resist including the multilayer polyester film and the photosensitive film without employing the cover film which causes the problem.
  • the dry film resist of the present invention does not generate an air void in the photosensitive layer by the fish-eye.
  • the problems are releasability between the multilayer polyester film used as a base film and the photosensitive film upon using the dry film resist and telescope upon winding.
  • the present invention provides a multilayer film including more than two layers as the multilayer film for the dry film resist, wherein layers having an adhesiveness difference of 1.2 to 5 times from the photosensitive layer is used as both surface layers of the film and the layers having an adhesiveness difference of 1.2 to 5 times includes a first surface layer containing 0.001 to 5 wt% of an additive; and a second surface layer containing no additive or less than 0.5 wt% of the additive.
  • the present invention provides a dry film resist in which a photosensitive layer is stacked on the second surface layer of the multilayer film.
  • the first surface layer contains 0.001 to 5 wt% of an additive and the second surface layer contains no additive or less than 0.5 wt% of the additive, wherein the adhesiveness a of the first surface layer and the adhesiveness b of the second surface layer meet the following equation:
  • the second surface layer having the higher adhesiveness holds the photosensitive layer and the first surface layer having the lower adhesiveness is easily released from the photosensitive layer, thereby notably enhancing the releasability between the multilayer base film and the photosensitive layer. Consequently, it is possible to use the dry film resist stably without a cover film having fish-eyes. Also, since the second surface layer having the higher adhesiveness firmly holds the photosensitive layer, it is possible to prevent the generation of the telescope upon winding .
  • the multilayer film is prepared by coextrusion and has a multilayer structure of more than two layers.
  • a film having a multilayer structure of two layers one layer is formed as the second surface layer having the higher adhesiveness and the other layer is formed as the first surface layer having the lower adhesiveness.
  • a film having a multilayer structure of three layers or more one outermost layer is formed as the second surface layer having the higher adhesiveness and the opposite outermost layer is formed as the first surface layer having the lower adhesiveness.
  • the different adhesiveness can be obtained using the additive, and the adhesive difference can be more enlarged by controlling kind and content of the used additive.
  • the additive may be particles, lubricant or a mixture thereof.
  • the particles When the particles are used as the additive, the number of protuberances on the surface of the film is increased or a surface roughness is increased to allow the control of a friction coefficient between the multilayer film and the photosensitive layer.
  • the lubricant When the lubricant is used as the additive, a surface tension on the surface of the multilayer film can be reduced.
  • Examples for the particles used as the additive may include inorganic particles such as hard calcium carbonate (CaCO 3 ) , silica (SiO 2 ) , barium sulfate (BaSO 4 ) , sodium oxide (NaO 2 ) , sodium sulfate (Na 2 SO 4 ) , kaolin and talc, and organic particles such as silicon resin, cross-linked polystyrene resin and cross-linked acrylic resin including cross-linked divinylbenzene polymethacrylate and cross-linked polymethacrylate, benzoguamine-formaldehyde resin, benzoguamine-melamine-formaldehyde resin and melamine- formaldehyde resin.
  • inorganic particles such as hard calcium carbonate (CaCO 3 ) , silica (SiO 2 ) , barium sulfate (BaSO 4 ) , sodium oxide (NaO 2 ) , sodium sulfate (Na 2 SO 4
  • the particles have a mean particle diameter of 0.1 to 10 ⁇ m. If the mean particle diameter is less than 0.1 ⁇ m, less effect of increasing the roughness is shown. If the mean particle diameter is greater than 10 ⁇ m, abnormal coarse protuberances, which is highly possible to act as foreign substances, may be generated.
  • examples for the lubricant used as the additive may include a higher fatty acid amide like ethylenebisstearamide, a higher fatty acid metal salt like calciumstearate and other higher fatty acid amide.
  • the content of the additive is 0.001 to 5 wt% for the polyester film of the first surface layer. If the content of the additive is less than 0.001 wt% for the film, an effect of contributing the surface roughness is low to make the control of the adhesiveness difficult. If the content of the additive is greater than 5 wt%, a large amount of coagulation or other foreign substances is generated. It is more preferable to use the content of 0.001 to 1 wt% for effective transparency and marketability of the film.
  • the content of the additive is less than 0.5 wt% for the polyester film of the second surface layer or no additive is added. If the content of the additive is greater than 0.5 wt% for the film, the adhesiveness difference to the photosensitive layer between the first surface layer and the second surface layer may become less than 1.2 times to result in the telescope upon winding .
  • the adhesiveness difference to the photosensitive layer between the first surface layer and the second surface layer is 1.2 to 5 times. If the adhesiveness difference is less than 1.2 times, the releasability of the film is deteriorated and telescope is highly able to be happened upon winding of the product.
  • the adhesiveness difference is greater than 5 times, the amount of the used additive is increased though the releasability of the film is increased, thereby resulting in rise of production cost because the amount used of the additive is increased. 1.4 to 1.6 times of the adhesiveness difference is more preferable for effective releasability with respect to the photosensitive layer .
  • a polyester film may be used as a film used in the multilayer film of the present invention.
  • the polyester used in the multilayer film is obtained by polycondensation of an acid component containing a dicarboxylic acid as its major component and a glycol component containing alkyl glycol as its major component.
  • the dicarboxylic acid contains, as its major component, terephthalic acid or alkylester or phenylester thereof, some of which may be substituted with bifunctional carboxylic acid such as isophthalic acid, oxyethoxy benzoic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid or an ester-forming derivative thereof.
  • the glycol component contains, as its major component, ethylene glycol, some of which may be substituted, for example, with propylene glycol, trimethylene glycol, 1,4- cyclohexanediol, 1, 4-cyclohexanedimethanol, 1,4- bisoxyethoxybenzene, bisphenol, polyoxyethylene glycol. Also, a monofunctional compound or a trifunctional compound may be used together in a small content.
  • a photosensitive liquid composition consisting of a polymeric binder, a photopolymerizable monomer, a photoinitiator and a solvent is prepared by a conventional manner well known in the art, and the applying and drying of the photosensitive liquid composition is also performed by a conventional manner well known in the art. Therefore, the photosensitive layer will not be described in detail.
  • the dry film resist according to the present invention may be used as a roll type dry film resist rolled so that the photosensitive layer of the dry film resist is brought in contact with the first surface layer of the multilayer film having lower adhesiveness.
  • the dry film resist according to the present invention does not employ a conventional gel-free polyethylene protective cover film. Therefore, it is possible to reduce generation a poor pattern such as a chip or open circuit by fish-eyes or foreign substances generated by the protective cover film upon formation of a wiring pattern.
  • Fig. 1 is an exemplary view of a wound dry film resist.
  • photosensitive layer 2 first surface layer of multilayer film 3: second surface layer of multilayer film
  • the adhesiveness was measured according to JIS Z-0237 No. 8 adhesiveness measurement protocol.
  • a sample in which a dry film resist photosensitive resin composition was coated on a base PET film was prepared.
  • a copper foil was laminated on the dry film resist photosensitive coating layer and the sample was then cut into a size of 200 mm in length and 25 mm in width.
  • the adhesiveness was measured by releasing the coating base PET film from the copper foil at a speed of 300 mm/min by an angle of 180 degree using an INSTRON Model 3365 with 1 kg load cell, in which the copper foil is held by a lower holding clip of the INSTRON and the coating base PET film is held by an upper holding clip of the INSTRON.
  • the mean particle diameter was measured using a laser diffraction particle size distribution measuring instrument (Beckman, Coulter LS13320) . A diameter corresponding to 50% of the volume accumulated from the smallest size of the particle when converted into a spherical shape was considered as the mean particle diameter.
  • lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0 C with effluence of methanol, to perform transesterification.
  • 1000 ppm of silica (SiO 2 , mean particle diameter: 2 /Jm) in the form of an ethylene glycol slurry was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0 C to obtain a polyester chip A having an intrinsic viscosity of 0.65.
  • the obtained polyester sheet was longitudinally stretched by 3.8 times at 100 0 C and stretched again by 4.2 times at 130 0 C, followed by the heat treatment at 220 0 C to thereby obtain a multilayer polyester film 1 with a thickness of 19 ⁇ m, in which a layer containing 1000 ppm of the silica (hereinafter, referred to as 'layer A') is staked on a layer containing no additive (hereinafter, referred to as ⁇ layer B' ) .
  • 'layer A' a layer containing 1000 ppm of the silica
  • ⁇ layer B' a layer containing no additive
  • lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0 C with effluence of methanol, to perform transesterification.
  • 1000 ppm of silica (SiO 2 , mean particle diameter: 2 jum) in the form of an ethylene glycol slurry was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0 C to obtain a polyester chip A having an intrinsic viscosity of 0.65.
  • lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0 C with effluence of methanol, to perform transesterification.
  • 200 ppm of silica (SiO 2 , mean particle diameter: 2 ⁇ m) in the form of an ethylene glycol sludge was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0 C to obtain a polyester chip C having an intrinsic viscosity of 0.65.
  • the respective polyester chips were melted at 280 0 C and coextruded, followed by rapid cooling to 20 0 C to obtain a polyester sheet .
  • the obtained polyester sheet was longitudinally stretched by 3.8 times at 100 0 C and stretched again by 4.2 times at 120 0 C, followed by the heat treatment at 220 0 C to thereby obtain a multilayer polyester film 2 with a thickness of 19 ⁇ m, in which a layer A is staked on a layer containing 200 ppm of the silica (hereinafter, referred to as ⁇ layer C ) .
  • polyester chips were melted at 280 0 C and coextruded, followed by rapid cooling to 20 °C to obtain a polyester sheet .
  • the obtained polyester sheet was longitudinally stretched by 3.8 times at 100 "C and stretched again by 4.2 times at 120 °C, followed by the heat treatment at
  • a layer B is staked on a layer containing 3000 ppm of the silica (hereinafter, referred to as 'layer D' ) .
  • Example 1 Preparation of dry film resist 1 On the layer B of the polyester film obtained in Preparation Example 1, a photosensitive liquid composition containing 0.5 wt% of acrylic acid, 7.5 wt% of methacrylic acid, 30 wt% of methylmethacrylate, 7.5 wt% of 2- ethylhexylacrylate , 2 wt% of benzophenone, 1 wt% of 4,4'- bis (diethylamino)benzophenone, 3 wt% of leuco crystal violet, 0.5 wt% of toluene sulfonic acid monohydrate, 0.5 wt% of diamond green GH, photopolymerizable monomers (10 wt% of 9G, 10 wt% of APG-400 and 10 wt% of BPE-500) and 13 wt% of methylethylketone for the total weight of the photosensitive liquid composition was coated and dried by a conventional method to prepare a dry film resist 1.
  • Preparation Example 2 a photosensitive liquid composition which is the same as in the Example 1 was coated and dried by a conventional method to prepare a dry film resist 2. The properties are shown in Table 1 below.
  • Example 3 Preparation of dry film resist 3 On the layer D of the polyester film obtained in Preparation Example 3, a photosensitive liquid composition which is the same as in the Example 1 was coated and dried by a conventional method to prepare a dry film resist 3. The properties are shown in Table 1 below.
  • a process was the same as in Example 2, but 5.5 wt% of silica was used to prepare a polyester layer A' and 5.1 wt% of silica was used to prepare a polyester layer C on which the photosensitive layer was stacked.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Materials For Photolithography (AREA)
  • Laminated Bodies (AREA)
  • Non-Metallic Protective Coatings For Printed Circuits (AREA)

Abstract

A multilayer film includes a first surface layer and a second surface layer which opposes to the first surface layer, wherein an adhesiveness a of the first surface layer and an adhesiveness b of the second surface layer meet the following equation: [Equation 1] b > a. The dry film resist according to the present invention does not employ a conventional gel -free polyethylene cover film. Therefore, it is possible to reduce generation a poor pattern such as a chip or open circuit by fish-eyes or foreign substances generated by the cover film upon formation of a wiring pattern.

Description

[DESCRIPTION]
[invention Title]
A MULTILAYER FILM FOR DRY FILM RESIST
[Technical Field]
The present invention relates to a multilayer film for a dry film resist used in fabrication of a printed circuit board, a lead frame and a ball grid array, and a dry film resist using the same.
[Background Art]
A dry film resist, which is also called as a dry film photoresist or a photosensitive film, has been used, since it has developed as a brand name 'RISTON' by Du Pont in 1968, in a lead frame used to mount a semiconductor integrated circuit or a ball grid array which is a large scale integrated circuit
(LSI) package in which semispherical solder terminals are arranged in a two-dimensional array on a bask side of a printed circuit board (PCB) mounted with a bare chip to substitute the lead, and particularly used as an epochal processing technique material for forming a circuit on a PCB which is basically used to connect components in various electronic appliances.
A conventional dry film resist consists of three layers, i.e., a base film layer, a photosensitive layer and a protective cover film.
The base film layer of the dry film resist employs a transparent film. In general, a polyester based film such as polyethyleneterephthalate (PET) film is used with a thickness of about 25 jL/m.
The photosensitive layer is obtained by coating and drying a photosensitive resin composition on the base film, and is formed from a negative or positive photosensitive resin composition. Also, according to a developing manner, the photosensitive layer is known to an alkali-developing type in which an alkali aqueous solution is used to develop and an organic solvent-developing type in which an organic solvent is used to develop, and the alkali-developing type tends to be increasingly used as compared with the organic solvent- developing type having problems such as stability in operation process, environmental pollution and high production cost.
The photosensitive layer is prepared by coating and drying a photosensitive resin composition generally consisting of, though its composition may vary as required mechanical and chemical properties and processing condition, a photopolymerizable multifunctional monomer, a photoinitiator inducing the photopolymerization of the multifunctional monomer, a polymeric binder providing mechanical strength, tenting property and adhesiveness to the photosensitive layer and, according to an object, additional additives such as dyes, stabilizers, adhesion promoter and thermal polymerization inhibitor. As the protective cover film, a polyolefin film such as a polyethylene film having good flexibility, chemical resistance and releasability is conventionally used. The protective cover film is prepared by kneading and extruding thermally molten raw material and then biaxially stretching or casting the extrudate .
The reason of using the protective cover film in the dry film resist is because the protective cover film prevents a telescope (an original form of product is not maintained, while the foam comes out) from being generated when winding the dry film resist after a photosensitive polymer is coated on the base film and dried, raises the releasability between the photosensitive layer and the base film, and acts as a cover for protecting the photosensitive layer from foreign substances such as dust . However, during preparation of the polyolefin film, a gel containing non-molten substances and heated substances is formed in the polyolefin film and the gel is called as a fish- eye since a micro-protuberance like a fish' s eye is present in the film after the film is formed. The fish-eye generally has a diameter of 30 to 600 μm and protuberated from the surface of the cover film to a height of 2 to 40 μm. The photosensitive layer, though it belongs to a solid, is not a hard solid of which shape is not deformed but has certain deformability . Therefore, the protuberated portion of the fish-eye of the protective cover film is transferred onto the photosensitive layer to thereby form a recess in the photosensitive layer., The formed recess generates an air void between the photosensitive layer and a substrate because the protective cover film is removed and the photosensitive layer is pressed on a substrate with heating when the dry film resist is laminated on the substrate, and the air void causes poor pattern such as a chip or an open circuit when forming a wiring pattern according to subsequent exposure, development and etching processes.
In order to solve the problem, Japanese Patent Publication Hll-153861 discloses a dry film resist employing a polyolefin cover film in which the number of fish-eyes with a major axis of greater than 80 μm is less than 5/m2, and Japanese Patent Publication 2003-342307 discloses a polyethylene film in which the number of fish-eyes with a major axis of 30 μm to 0.20 mm is less than 40/m2 and the number of fish-eyes with a major axis of greater than 0.20 mm is less than 1.0/m2, and a method of preparing the same. However, the production cost of the dry film resist employing the polyethylene with a low fish-eye density, which is hard to be prepared and generally high-priced, is raised.
[Disclosure]
[Technical Problem]
An object of the present invention is to provide a multilayer film which enhances releasability between a photosensitive layer and a base film without using a protective cover film in a dry film resist, and a dry film resist using the same.
[Technical Solution]
In one aspect, to solve the problems, the present invention provides a multilayer film including a first surface layer and a second surface layer which opposes to the first surface layer, wherein an adhesiveness a of the first surface layer and an adhesiveness b of the second surface layer meet the following equation: [Equation 1] b > a.
The first surface layer contains 0.001 to 5 wt% of an additive and the second surface layer contains no additive or less than 0.5 wt% of an additive, and the adhesiveness a and b of the first surface layer and the second surface layer meet the following equation:
[Equation 2] b/a = 1.2 ~ 5. In another aspect, the present invention provides a functional film in which a functional layer is stacked on the second surface layer having a higher adhesiveness of the multilayer film as described above.
Example for the functional film may include a multilayer film, preferably a dry film resist in which a photosensitive layer is stacked on a multilayer polyester film.
The conventional dry film resist employs a protective cover film and therefore has a problem of a fish-eye. However, the present invention provides the dry film resist including the multilayer polyester film and the photosensitive film without employing the cover film which causes the problem.
Therefore, the dry film resist of the present invention does not generate an air void in the photosensitive layer by the fish-eye. At this time, the problems are releasability between the multilayer polyester film used as a base film and the photosensitive film upon using the dry film resist and telescope upon winding.
Accordingly, the present invention provides a multilayer film including more than two layers as the multilayer film for the dry film resist, wherein layers having an adhesiveness difference of 1.2 to 5 times from the photosensitive layer is used as both surface layers of the film and the layers having an adhesiveness difference of 1.2 to 5 times includes a first surface layer containing 0.001 to 5 wt% of an additive; and a second surface layer containing no additive or less than 0.5 wt% of the additive.
Also, in further another aspect, the present invention provides a dry film resist in which a photosensitive layer is stacked on the second surface layer of the multilayer film.
Specifically, the first surface layer contains 0.001 to 5 wt% of an additive and the second surface layer contains no additive or less than 0.5 wt% of the additive, wherein the adhesiveness a of the first surface layer and the adhesiveness b of the second surface layer meet the following equation:
[Equation 2] b/a = 1.2 ~ 5.
When the dry film resist prepared as described above is wound in a roll shape as shown in Fig. 1, one side of the photosensitive layer is in contact with the second surface layer of the multilayer film having a higher adhesiveness to the photosensitive layer and the other side of the photosensitive layer is in contact with the first surface layer of the multilayer film having a lower adhesiveness.
Therefore, when the wound dry film resist is released, the second surface layer having the higher adhesiveness holds the photosensitive layer and the first surface layer having the lower adhesiveness is easily released from the photosensitive layer, thereby notably enhancing the releasability between the multilayer base film and the photosensitive layer. Consequently, it is possible to use the dry film resist stably without a cover film having fish-eyes. Also, since the second surface layer having the higher adhesiveness firmly holds the photosensitive layer, it is possible to prevent the generation of the telescope upon winding .
The multilayer film is prepared by coextrusion and has a multilayer structure of more than two layers. In a film having a multilayer structure of two layers, one layer is formed as the second surface layer having the higher adhesiveness and the other layer is formed as the first surface layer having the lower adhesiveness. In a film having a multilayer structure of three layers or more, one outermost layer is formed as the second surface layer having the higher adhesiveness and the opposite outermost layer is formed as the first surface layer having the lower adhesiveness.
The different adhesiveness can be obtained using the additive, and the adhesive difference can be more enlarged by controlling kind and content of the used additive.
The additive may be particles, lubricant or a mixture thereof. When the particles are used as the additive, the number of protuberances on the surface of the film is increased or a surface roughness is increased to allow the control of a friction coefficient between the multilayer film and the photosensitive layer. When the lubricant is used as the additive, a surface tension on the surface of the multilayer film can be reduced.
Examples for the particles used as the additive may include inorganic particles such as hard calcium carbonate (CaCO3) , silica (SiO2) , barium sulfate (BaSO4) , sodium oxide (NaO2) , sodium sulfate (Na2SO4) , kaolin and talc, and organic particles such as silicon resin, cross-linked polystyrene resin and cross-linked acrylic resin including cross-linked divinylbenzene polymethacrylate and cross-linked polymethacrylate, benzoguamine-formaldehyde resin, benzoguamine-melamine-formaldehyde resin and melamine- formaldehyde resin.
The particles have a mean particle diameter of 0.1 to 10 μm. If the mean particle diameter is less than 0.1 μm, less effect of increasing the roughness is shown. If the mean particle diameter is greater than 10 μm, abnormal coarse protuberances, which is highly possible to act as foreign substances, may be generated.
Meanwhile, examples for the lubricant used as the additive may include a higher fatty acid amide like ethylenebisstearamide, a higher fatty acid metal salt like calciumstearate and other higher fatty acid amide.
In the case of the first surface layer, the content of the additive is 0.001 to 5 wt% for the polyester film of the first surface layer. If the content of the additive is less than 0.001 wt% for the film, an effect of contributing the surface roughness is low to make the control of the adhesiveness difficult. If the content of the additive is greater than 5 wt%, a large amount of coagulation or other foreign substances is generated. It is more preferable to use the content of 0.001 to 1 wt% for effective transparency and marketability of the film.
In the case of the second surface layer, the content of the additive is less than 0.5 wt% for the polyester film of the second surface layer or no additive is added. If the content of the additive is greater than 0.5 wt% for the film, the adhesiveness difference to the photosensitive layer between the first surface layer and the second surface layer may become less than 1.2 times to result in the telescope upon winding . In the multilayer film, the adhesiveness difference to the photosensitive layer between the first surface layer and the second surface layer is 1.2 to 5 times. If the adhesiveness difference is less than 1.2 times, the releasability of the film is deteriorated and telescope is highly able to be happened upon winding of the product. If the adhesiveness difference is greater than 5 times, the amount of the used additive is increased though the releasability of the film is increased, thereby resulting in rise of production cost because the amount used of the additive is increased. 1.4 to 1.6 times of the adhesiveness difference is more preferable for effective releasability with respect to the photosensitive layer .
As a film used in the multilayer film of the present invention, a polyester film may be used. The polyester used in the multilayer film is obtained by polycondensation of an acid component containing a dicarboxylic acid as its major component and a glycol component containing alkyl glycol as its major component. The dicarboxylic acid contains, as its major component, terephthalic acid or alkylester or phenylester thereof, some of which may be substituted with bifunctional carboxylic acid such as isophthalic acid, oxyethoxy benzoic acid, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid or an ester-forming derivative thereof. The glycol component contains, as its major component, ethylene glycol, some of which may be substituted, for example, with propylene glycol, trimethylene glycol, 1,4- cyclohexanediol, 1, 4-cyclohexanedimethanol, 1,4- bisoxyethoxybenzene, bisphenol, polyoxyethylene glycol. Also, a monofunctional compound or a trifunctional compound may be used together in a small content.
In the preparation of the photosensitive layer used in the dry film resist according to the present invention, a photosensitive liquid composition consisting of a polymeric binder, a photopolymerizable monomer, a photoinitiator and a solvent is prepared by a conventional manner well known in the art, and the applying and drying of the photosensitive liquid composition is also performed by a conventional manner well known in the art. Therefore, the photosensitive layer will not be described in detail.
The dry film resist according to the present invention may be used as a roll type dry film resist rolled so that the photosensitive layer of the dry film resist is brought in contact with the first surface layer of the multilayer film having lower adhesiveness.
[Advantageous Effects]
The dry film resist according to the present invention does not employ a conventional gel-free polyethylene protective cover film. Therefore, it is possible to reduce generation a poor pattern such as a chip or open circuit by fish-eyes or foreign substances generated by the protective cover film upon formation of a wiring pattern.
[Description of Drawings]
The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:
Fig. 1 is an exemplary view of a wound dry film resist. [Description of main elements] 1: photosensitive layer 2 : first surface layer of multilayer film 3: second surface layer of multilayer film
[Best Mode]
Practical and presently preferred embodiments of the present invention are illustrative as shown in the following Examples. However, it will be appreciated that those skilled in the art, on consideration of this disclosure, may make modifications and improvements within the spirit and scope of the present invention. Methods of measuring physical properties are as follows:
1. Measurement of adhesiveness: the adhesiveness was measured according to JIS Z-0237 No. 8 adhesiveness measurement protocol. A sample in which a dry film resist photosensitive resin composition was coated on a base PET film was prepared. A copper foil was laminated on the dry film resist photosensitive coating layer and the sample was then cut into a size of 200 mm in length and 25 mm in width. With the coating base PET film being partially released at one end of the sample, the adhesiveness was measured by releasing the coating base PET film from the copper foil at a speed of 300 mm/min by an angle of 180 degree using an INSTRON Model 3365 with 1 kg load cell, in which the copper foil is held by a lower holding clip of the INSTRON and the coating base PET film is held by an upper holding clip of the INSTRON.
2. Measurement of a mean particle diameter: the mean particle diameter was measured using a laser diffraction particle size distribution measuring instrument (Beckman, Coulter LS13320) . A diameter corresponding to 50% of the volume accumulated from the smallest size of the particle when converted into a spherical shape was considered as the mean particle diameter.
3. Measurement of a haze: the haze was measured using ASTM D1003. The polyester film cut into a chip of 5 cm X 5 cm size was put in a haze meter (Nippon Denshoku, NDH type) , which was then transmits light of 540 nm wavelength through the chip. The calculation was performed by the following equation:
Haze (%) = (total scattered light/total transmitted light) X 100. [Preparation Example 1] Preparation of multilayer polyester film 1
In a reactor, lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0C with effluence of methanol, to perform transesterification. After completion of the transesterification, 1000 ppm of silica (SiO2, mean particle diameter: 2 /Jm) in the form of an ethylene glycol slurry was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0C to obtain a polyester chip A having an intrinsic viscosity of 0.65.
In a reactor, lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0C with effluence of methanol, to perform transesterification. After that, polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0C to obtain a polyester chip B having an intrinsic viscosity of 0.65. The respective polyester chips were melted at 280 0C and coextruded, followed by rapid cooling to 20 0C to obtain a polyester sheet. The obtained polyester sheet was longitudinally stretched by 3.8 times at 100 0C and stretched again by 4.2 times at 130 0C, followed by the heat treatment at 220 0C to thereby obtain a multilayer polyester film 1 with a thickness of 19 μm, in which a layer containing 1000 ppm of the silica (hereinafter, referred to as 'layer A') is staked on a layer containing no additive (hereinafter, referred to as λ layer B' ) . [Preparation Example 2] Preparation of multilayer polyester film 2
In a reactor, lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0C with effluence of methanol, to perform transesterification. After completion of the transesterification, 1000 ppm of silica (SiO2, mean particle diameter: 2 jum) in the form of an ethylene glycol slurry was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0C to obtain a polyester chip A having an intrinsic viscosity of 0.65.
In a reactor, lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0C with effluence of methanol, to perform transesterification. After completion of the transesterification, 200 ppm of silica (SiO2, mean particle diameter: 2 μm) in the form of an ethylene glycol sludge was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0C to obtain a polyester chip C having an intrinsic viscosity of 0.65.
The respective polyester chips were melted at 280 0C and coextruded, followed by rapid cooling to 20 0C to obtain a polyester sheet . The obtained polyester sheet was longitudinally stretched by 3.8 times at 100 0C and stretched again by 4.2 times at 120 0C, followed by the heat treatment at 220 0C to thereby obtain a multilayer polyester film 2 with a thickness of 19 μm, in which a layer A is staked on a layer containing 200 ppm of the silica (hereinafter, referred to as λ layer C ) .
[Preparation Example 3] Preparation of multilayer polyester film 3
In a reactor, lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0C with effluence of methanol, to perform transesterification. After completion of the transesterification, 3000 ppm of silica (SiO2, mean particle diameter: 2 μm) in the form of an ethylene glycol slurry was added in the product and polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0C to obtain a polyester chip D having an intrinsic viscosity of
0.65.
In a reactor, lOOOg of dimethylterephthalate, 576 g of ethylene glycol and 0.8 g of magnesium acetate catalyst were put and reacted for 5 hours at 250 0C with effluence of methanol, to perform transesterification. After that, polycondensation was performed for 4 hours under vacuum of 1 mmHg at 280 0C to obtain a polyester chip B having an intrinsic viscosity of 0.65.
The respective polyester chips were melted at 280 0C and coextruded, followed by rapid cooling to 20 °C to obtain a polyester sheet . The obtained polyester sheet was longitudinally stretched by 3.8 times at 100 "C and stretched again by 4.2 times at 120 °C, followed by the heat treatment at
220 0C to thereby obtain a multilayer polyester film 2 with a thickness of 19 μm, in which a layer B is staked on a layer containing 3000 ppm of the silica (hereinafter, referred to as 'layer D' ) . [Example 1] Preparation of dry film resist 1 On the layer B of the polyester film obtained in Preparation Example 1, a photosensitive liquid composition containing 0.5 wt% of acrylic acid, 7.5 wt% of methacrylic acid, 30 wt% of methylmethacrylate, 7.5 wt% of 2- ethylhexylacrylate , 2 wt% of benzophenone, 1 wt% of 4,4'- bis (diethylamino)benzophenone, 3 wt% of leuco crystal violet, 0.5 wt% of toluene sulfonic acid monohydrate, 0.5 wt% of diamond green GH, photopolymerizable monomers (10 wt% of 9G, 10 wt% of APG-400 and 10 wt% of BPE-500) and 13 wt% of methylethylketone for the total weight of the photosensitive liquid composition was coated and dried by a conventional method to prepare a dry film resist 1. The properties are shown in Table 1 below. [Example 2] Preparation of dry film resist 2
On the layer C of the polyester film obtained in
Preparation Example 2, a photosensitive liquid composition which is the same as in the Example 1 was coated and dried by a conventional method to prepare a dry film resist 2. The properties are shown in Table 1 below.
[Example 3] Preparation of dry film resist 3 On the layer D of the polyester film obtained in Preparation Example 3, a photosensitive liquid composition which is the same as in the Example 1 was coated and dried by a conventional method to prepare a dry film resist 3. The properties are shown in Table 1 below.
[Comparative Example 1] Preparation of comparative dry film resist 1
A process was the same as in Example 2, but 5.5 wt% of silica was used to prepare a polyester layer A' and 5.1 wt% of silica was used to prepare a polyester layer C on which the photosensitive layer was stacked.
[Table 1] Physical properties of Examples and Comparative Example
Figure imgf000021_0001

Claims

[CLAIMS] [Claim l]
A multilayer film comprising first surface layer and a second surface layer which opposes to the first surface layer, wherein an adhesiveness a of the first surface layer and an adhesiveness b of the second surface layer meet the following equation:
[Equation 1] b > a.
[Claim 2]
The multilayer film as set forth in claim 1, wherein the first surface layer contains 0.001 to 5 wt% of an additive and the second surface layer contains no additive or less than 0.5 wt% of an additive, and the adhesiveness a and b of the first surface layer and the second surface layer meet the following equation:
[Equation 2] b/a = 1.2 ~ 5.
[Claim 3]
The multilayer film as set forth in claim 2, wherein the multilayer film is prepared by coextrusion. [Claim 4 ]
The multilayer film as set forth in claim 2, wherein the additive includes at least one inorganic particle selected from the group consisting of hard calcium carbonate, silica, barium sulfate, sodium oxide, sodium sulfate, kaolin and talc; at least one organic particle selected from the group consisting of silicon resin, cross-linked acrylic resin and cross-linked polystyrene resin, benzoguanamine-formaldehyde resin, benzoguanamine-melamine-formaldehyde resin and melamine-formaldehyde resin; at least one lubricant selected from the group consisting of a higher fatty acid amide like ethylenebisstearamide, a higher fatty acid metal salt like calciumstearate and other higher fatty acid amide,- and a mixture thereof .
[Claim 5]
The light diffusion film as set forth in claim 4, wherein the inorganic particles and the organic particles have a mean particle size of 1 to 10 μm.
[Claim 6]
A functional film, wherein a functional layer is stacked on the second surface layer having higher adhesiveness of the multilayer film as set forth in claim 1 or 2. [Claim 7]
A dry film resist, wherein a photosensitive layer is stacked on the second surface layer having higher adhesiveness of the multilayer film as set forth in claim 1 or 2.
[Claim 8]
The dry film resist as set forth in claim 7, wherein the first surface layer contains 0.001 to 5 wt% of an additive and the second surface layer contains no additive or less than 0.5 wt% of an additive, and the adhesiveness a of the first surface layer and the adhesiveness b of the second surface layer meet the following equation:
[Equation 2] b/a = 1.2 ~ 5.
[Claim 9]
The dry film resist as set forth in claim 8, wherein the multilayer film is prepared by coextrusion.
[Claim IO]
The dry film resist as set forth in claim 8, wherein the additive includes at least one inorganic particle selected from the group consisting of hard calcium carbonate, silica, barium sulfate, sodium oxide, sodium sulfate, kaolin and talc; at least one organic particle selected from the group consisting of silicon resin, cross-linked acrylic resin and cross-linked polystyrene resin, benzoguanamine-formaldehyde resin, benzoguanamine-melamine-formaldehyde resin and melamine-formaldehyde resin; at least one lubricant selected from the group consisting of a higher fatty acid amide like ethylenebisstearamide, a higher fatty acid metal salt like calciumstearate and other higher fatty acid amide; and a mixture thereof .
[Claim 11]
The dry film resist as set forth in claim 10, wherein the inorganic particles and the organic particles have a mean particle size of 1 to 10 μm.
[Claim 12]
The dry film resist as set forth in claim 8, wherein the dry film resist ofroll type prepared by rolling the dry film resist so that the photosensitive layer is in contact with the first surface layer of the multilayer film having a lower adhesiveness .
PCT/KR2008/007900 2007-12-31 2008-12-31 A multilayer film for dry film resist WO2009084929A2 (en)

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