KR101463220B1 - Coverlay - Google Patents

Abstract

A mixture of paraphenylenediamine and 4,4'-diaminodiphenyl ether as diamine components, pyromellitic dianhydride as acid dianhydride component and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride The coverlay formed by using a polyimide film and applying an adhesive to one side of the polyimide film is suitable for bonding to a flexible printed wiring board using lead-free solder, solving both of dimensional change and heat resistance.

Polyimide film, coverlay

Description

Coverage {COVERLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cover lay, and more particularly to a cover lay obtained by forming an adhesive layer on one side of a polyimide film as a base.

BACKGROUND ART Printed wiring boards are widely used in electronic and electric devices. Among them, the flexible printed wiring board which can be bent is widely used for bending parts such as personal computers and mobile phones, and parts requiring bending of hard disks and the like. The wiring circuit of the flexible printed wiring board is formed by chemically etching a metal foil laminated integrally with the heat resistant resin. Since the surface of the wiring circuit is easily oxidized, a protective layer is formed to cover the surface, It is usually called a coverlay. Various types of polyimide films are generally used as the base material of the coverlay for protecting the substrate and the wiring board of such a flexible printed wiring board.

Representative examples of the polyimide film include a polyimide film in which an anhydride of pyromellitic acid is used as an acid dianhydride component and 4,4'-diaminodiphenyl ether is used as a diamine component. Such a polyimide film has a structure excellent in balance of mechanical and thermal properties, and is widely used industrially as a general-purpose product. However, the polyimide film comprising pyromellitic acid dianhydride and 4,4'-diaminodiphenyl ether has an advantage of being easy to bend, whereas when it is used as a coverlay, it is too soft and prone to wrinkles. When wrinkles are formed, air enters the parts and corrosion of the wiring occurs, resulting in a problem of causing defective wiring.

In addition, the polyimide film comprising pyromellitic acid dianhydride and 4,4'-diaminodiphenyl ether has a large coefficient of thermal expansion (CTE) and hygroscopic expansion coefficient (CHE) and a high water absorption rate, The change is great. Therefore, when used as a cover layer, there is a problem that a dimensional change with respect to the wiring board is different, and warping occurs when the cover is joined.

In order to solve such a problem, a method of forming a coverlay using a substrate having a small dimensional change other than a polyimide film, for example, a liquid crystal film (see, for example, Patent Document 1) The film has a problem in that the base material is deformed at the time of soldering because the heat resistance of the film is lower than that of the polyimide film. Particularly, in recent years, lead-free solders that do not use lead due to environmental problems are widely used. However, since most of the lead-free solders have a melting point higher than that of the lead-containing solder, the problem of base material deformation of the liquid crystal film becomes more serious.

Patent Document 1: JP-A-2000-280341

An object of the present invention is to solve both of the problems of dimensional change and heat resistance of such coverlay, and to provide a coverlay suitable for bonding to a flexible printed wiring board using lead-free solder.

In order to achieve the above object, the present invention adopts the following configuration.

(1) A composition comprising (1) paraphenylenediamine and 4,4'-diaminodiphenyl ether as diamine components, pyromellitic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride as an acid dianhydride component A cover layer formed by using a polyimide film mainly composed of water and forming an adhesive layer on one side of the polyimide film.

(2) The polyimide film of (1), wherein the polyimide film contains 10 to 50 mol% of paraphenylenediamine and 50 to 90 mol% of 4,4'-diaminodiphenyl ether as a diamine component, And 50 to 99 mol% of pyromellitic acid dianhydride and 1 to 50 mol% of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride.

(3) The polyimide film according to the above item (1) or (2), wherein the polyimide film has a modulus of elasticity of 3 to 7 GPa, a coefficient of linear expansion at 50 to 200 캜 of 5 to 20 ppm / , A water absorption percentage of 3% or less, and a heat shrinkage ratio at 200 占 폚 for 1 hour of 0.1% or less.

(4) The coverlay according to any one of (1) to (3), wherein the adhesive is mainly composed of at least one selected from an epoxy resin, an acrylic resin and a polyimide resin.

According to the present invention, it is possible to provide a coverlay which is not deformed even when lead-free solder is used. Further, it is possible to provide a coverlay excellent in dimensional stability and heat resistance.

The coverlay of the present invention is for protecting the base material and the wiring board of the flexible printed wiring board. A polyimide film is used as the base material, and an adhesive is formed on one side of the polyimide film.

At this time, as the polyimide film of the substrate, paraphenylenediamine and 4,4'-diaminodiphenyl ether as diamine components, pyromellitic acid dianhydride and 3,3 ', 4,4'-bis Is a polyimide film mainly composed of phenyltetracarboxylic dianhydride. Namely, it is preferable to use four kinds of dianhydrides such as paraphenylenediamine, 4,4'-diaminodiphenyl ether, pyromellitic dianhydride and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride as essential components, These are only four kinds, or a polyimide film obtained by adding a small amount of other components to these four kinds. Preferably, 10 to 50 mol% of paraphenylenediamine and 50 to 90 mol% of 4,4'-diaminodiphenyl ether are used as the diamine component and 50 to 99 mol of pyromellitic dianhydride as the acid dianhydride component And 1 to 50 mol% of 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride are used as the polyimide film. More preferably, the elastic modulus is 3 to 7 GPa, the linear expansion coefficient at 50 to 200 캜 is 5 to 20 ppm / 캜, the expansion coefficient of humidity is 25 ppm /% RH or less, the water absorption rate is 3% And a heat shrinkage ratio of 0.10% or less. If the amount of the paraphenylenediamine is too much, the hardening becomes too hard. If the paraphenylenediamine is too small, it is too soft. Therefore, it is preferably 10 to 50 mol%, more preferably 15 to 45 mol%, and still more preferably 20 to 40 mol%. It is preferably 50 to 90 mol%, more preferably 55 to 85 mol%, still more preferably 60 to 80 mol%, because the amount of 4,4'-diaminodiphenyl ether is too much, to be. When the amount of pyromellitic dianhydride is too much, it becomes hard and when it is too small, it softens. Therefore, it is preferably 50 to 99 mol%, more preferably 55 to 95 mol%, still more preferably 60 to 90 mol%. Too much 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride tends to soften, and when it is too small, it hardens, so it is preferably 1 to 50 mol%, more preferably 5 to 45 mol% More preferably from 15 to 35 mol%. The elastic modulus, which is an index of hardness, is preferably in the range of 3 to 7 GPa, and when it is more than 7 GPa, it is too hard. When it is less than 3 GPa, it is too soft. The coefficient of linear expansion is preferably from 5 to 20 ppm / 占 폚. If it exceeds 20 ppm / 占 폚, the dimensional change caused by heat is too large, and if it is smaller than 5 ppm / 占 폚, the difference from the coefficient of linear expansion Warpage occurs. If the humidity expansion coefficient exceeds 25 ppm /% RH, the dimensional change due to humidity is too large, so the humidity expansion coefficient is preferably 25 ppm /% RH or less. If the water absorption rate exceeds 3%, the dimensional change of the film becomes large due to the influence of the absorbed water, so that it is preferably 3% or less. When the heat shrinkage ratio at 200 ° C for one hour exceeds 0.10%, the dimensional change due to heat also becomes large, so the heat shrinkage rate is preferably 0.10% or less.

As described above, a small amount of diamine may be added to the polyimide film in the present invention in addition to paraphenylenediamine or 4,4'-diaminodiphenyl ether. In addition to pyromellitic acid dianhydride or 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, a small amount of acid dianhydride may be added. Specific diamines and acid dianhydrides include, but are not limited to, the following.

(1) acid dianhydride

2,3 ', 3,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride, 2,3,6,7-naphthalenedicarboxylic acid Acid dianhydride, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5,6-tetracarboxylic acid dianhydride, 1,2,4,5-naphthalenetetracarboxylic acid Dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-decahydronaphthalenetetracarboxylic acid dianhydride, 4,8-dimethyl-1,2,5,6 - hexahydronaphthalenetetracarboxylic acid dianhydride, 2,6-dichloro-1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 2,7-dichloro-1,4,5,8-naphthalenetetracar Tetrachloro-1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,8,9,10-phenanthrenetetracarboxylic acid dianhydride, 2,3,6,7-tetrachloro-1,4,5,8- Bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1- Bis (3,4-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, benzene (2,3-dicarboxyphenyl) methane dianhydride, bis -1,2,3,4-tetracarboxylic acid dianhydride, 3,4,3 ', 4'-benzophenonetetracarboxylic acid dianhydride and the like.

(2)

Diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, m-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,4'-diaminodiphenylpropane, 3 , 3'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, benzidine, 4,4'- Diaminodiphenylsulfide, 3,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,4'-diamino di (4-aminophenyl) diethylsilane, 3,3'-dichlorobenzidine, bis- (4-aminophenyl) (4-aminophenyl) -N-phenylamine, bis- (4-aminophenyl) -N-methylamine, Diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-dimethyl-3 ', 4-diaminobiphenyl 3,3'-dimethoxybenzidine, 2,4- bis (p- -Amino -t- butylphenyl) ether, bis (p-amino-β- -t- butylphenyl) ether, bis p- (2-methyl-4-acetaminophen butyl) benzene, p--bis- (1,1-dimethyl Aminopentyl) benzene, m- xylylenediamine, p- xylenediamine, 1,3-diaminoadamantane, 3,3'-diamino-1,1'- Diaminocyclohexane, diaminomethyl 1,1'-diadamantane, bis ( p -aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-methylheptamethylenediamine, 4 , 4'-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine, 3-methoxyhexa- Diaminocyclohexane, 1,12-diaminooctadecane, 2,5-diamino-1,2-diaminohexadecane, 2,5-diaminoheptamethylene diamine, 3,4-oxadiazole, 2,2-bis (4-amino Phenyl), N- hexafluoropropane (3-aminophenyl) -4-amino-benzamide, 4-amino-3-aminobenzoate and the like.

In producing the polyimide film, a polyamic acid, which is a precursor of polyimide, is first synthesized by first polymerizing a diamine and an acid dianhydride, and then the film is formed into a film or imidized to form a polyimide film . In the present invention, at least two kinds of diamine components and at least two kinds of acid dianhydrides are used, but these components may be mixed at one time and polymerized at random, or they may be mixed in sequence by appropriate combination to perform block polymerization. For example, first, para-phenylenediamine and pyromellitic dianhydride are reacted, and then 4,4'-diaminodiphenyl ether and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Or by first reacting 4,4'-diaminodiphenyl ether with pyromellitic dianhydride, and then reacting p-phenylenediamine with 3,3 ', 4,4'-biphenyltetracarboxylic acid Block polymerization in which dianhydride is added, and the like. As the solvent used in the polymerization, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylformamide, dimethylsulfoxide, It is not limited. Various catalysts represented by tertiary amines such as β -picoline and various dehydrating agents typified by organic carboxylic anhydrides such as acetic anhydride may be suitably used. In addition, various fillers such as silica, alumina, calcium hydrogen phosphate, and calcium phosphate may be added for the purpose of improving slipperiness of the film.

The polymerization may be carried out by any known method, for example, (1) to (5).

(1) First, all the aromatic diamine components are introduced into a solvent, and then the aromatic tetracarboxylic acid components are added so as to have the same amount as the total aromatic diamine component.

(2) First, all the aromatic tetracarboxylic acid components are added to the solvent, and then the aromatic diamine component is added to the aromatic tetracarboxylic acid components in the same amount.

(3) After adding one aromatic diamine compound into the solvent, the aromatic tetracarboxylic acid compound is added to the reaction component in such a ratio that the amount of the aromatic tetracarboxylic acid compound becomes 95 to 105 mol%, and the other aromatic diamine compound is added And then adding the aromatic tetracarboxylic acid compound so that the total aromatic diamine component and the total aromatic tetracarboxylic acid component are substantially equal in amount and polymerizing.

(4) An aromatic tetracarboxylic acid compound is placed in a solvent, and after mixing for a time required for the reaction in such a proportion that one aromatic diamine compound accounts for 95 to 105 mol% of the reaction component, the aromatic tetracarboxylic acid compound is added And then adding the other aromatic diamine compound so that the total aromatic diamine component and the total aromatic tetracarboxylic acid component are substantially equal in amount, and then polymerizing.

(5) A method for preparing a polyamic acid solution (A) by reacting one aromatic diamine component and an aromatic tetracarboxylic acid component in a solvent so that one of the aromatic diamine component and the aromatic tetracarboxylic acid is in excess, The acids are reacted so that either one is excessive, and the polyamic acid solution (B) is adjusted. The polyamic acid solutions (A) and (B) thus obtained are mixed and the polymerization is completed. At this time, when the aromatic diamine component is excessive in adjusting the polyamic acid solution (A), the aromatic tetracarboxylic acid component is excessively increased in the polyamic acid solution (B), and the polyamic acid solution (A (A) and (B) are mixed in an excessive amount of an aromatic diamine component in the polyamic acid solution (B), and when the aromatic tetracarboxylic acid component The entire diamine component and the aromatic tetracarboxylic acid components are adjusted so as to be substantially equal in amount.

The polymerization method is not limited to these, and other known methods may be used.

The polyamic acid solution thus obtained contains a solid content of 5 to 40% by weight, preferably 10 to 30% by weight, and the viscosity thereof is 10 to 2,000 Pa · s, as measured by a Brookfield viscometer, Of 100 to 100 < RTI ID = 0.0 > OOPa < / RTI > is preferably used for stable feed. In addition, the polyamic acid in the organic solvent solution may be partially imidized.

The thickness of the polyimide film is not particularly limited, but is preferably 1 to 225 μm, more preferably 3 to 175 μm, and more preferably 5 to 125 μm. If it is too thick, it is likely to be wrapped up in a roll-like state, and if it is too thin, wrinkles and the like tend to occur.

An adhesive is applied to one side of the polyimide film as described above, and a coverlay is formed thereon. As the adhesive, at least one kind selected from an epoxy resin, an acrylic resin and a polyimide resin is preferable. These adhesives may be added with various kinds of rubber, plasticizer, curing agent, flame retardant such as phosphorus, and various other additives for the purpose of providing flexibility. In addition, a thermoplastic polyimide is mainly used as the polyimide resin in many cases, but a thermosetting polyimide may also be used. In the case of a polyimide resin, a solvent is not usually required in many cases, but polyimide which is soluble in an appropriate organic solvent may be used.

The thickness of the adhesive is not particularly limited as long as it can sufficiently bond the wiring of the flexible wiring board and can protect the wiring. For example, when the wiring thickness is 18 mu m, the thickness of the adhesive is preferably 10 to 100 mu m, And preferably 15 to 50 mu m. Further, for example, when the wiring thickness is 8 占 퐉, the adhesive thickness of 5 to 50 占 퐉 is good and the adhesive thickness of 12.5 to 25 占 퐉 is better. If the adhesive is too thin, wiring can not be sufficiently filled between the wires, and air may enter. If the adhesive is too thick, the thickness of the above range is selected because it affects the dimensional change of the polyimide film of the substrate.

In order to protect the adhesive, it is preferable that a cover sheet formed in this manner is pasted with a protective sheet immediately before bonding with the flexible back plate. Examples of the protective sheet include a polyester film, a polyethylene film, a polypropylene film, and a polyvinyl chloride film, and these films are coated with a known micro-adhesive agent.

The coverlay of the present invention is used for bonding with a flexible printed wiring board. Examples of the method for forming the wiring of the wiring board include a subtractive method, a semi-additive method and a pull additive method.

The subtractive method is a method in which a wiring is formed by bonding a copper foil on a polyimide film with an adhesive interposed therebetween and etching the copper foil in the form of a wiring pattern or a method of directly forming a copper layer On a polyimide film, and etching the copper layer in the form of a wiring pattern to form a wiring. When a copper foil is bonded, a rolled copper foil or an electrolytic copper foil is used as the copper foil. When a wiring is formed, usually a photoresist layer is formed on a copper foil, and the photoresist layer is selectively patterned in a wiring pattern by selective exposure and development, and copper is etched using the patterned photoresist layer as an etching mask , And then the photoresist layer is completely removed. At this time, a liquid or dry film resist is used as the photoresist, and a solution such as iron chloride, copper chloride, or peracid is used as the etching solution.

The semi-additive method is a method in which a metal layer to be a seed layer is formed on a polyimide film directly or with an adhesive therebetween, a photoresist layer is formed on the seed layer, and a photoresist layer is selectively exposed and developed And the patterned photoresist layer is used as a plating mask to form wirings on the seed layer by electroless plating or electrolytic plating. After that, the photoresist is completely removed, and finally, the seed layer of the portion other than the wiring is etched It means a method of removing. At this time, nickel, chrome, aluminum, lead, copper, tin, zinc, iron, silver and gold are used alone or as an alloy for the seed layer metal. Lead, copper, nickel, chromium, tin, zinc, silver, gold, or the like is used as the electroless plating or electrolytic plating metal for the photoresist, and an etchant suitable for the metal of the seed layer Is used.

The pull-add method is a method in which a photoresist layer is formed directly on a polyimide film or on an adhesive, the photoresist layer is patterned in a wiring pattern by selective exposure and development, and the patterned photoresist layer is subjected to electroless plating To form a wiring, and then to completely remove the photoresist. At this time, a liquid or a dry film resist is used as the photoresist, and copper, nickel, lead, chromium, tin, zinc, silver, gold and the like are used as the electroless plating metal.

Copper is preferably used as the metal used in the various wiring forming methods as described above. Although the formed wiring is used as an electric or electronic circuit, a metal having a resistance higher than that of copper is undesirable because the electric conductivity is deteriorated. In addition, if the metal is denser than copper, it is also not preferable because the electrical conductivity deteriorates. However, since copper tends to be rusted and may easily be corroded, it is optional to form a metal such as tin or lead, aluminum, nickel, silver or gold on copper for the purpose of protecting copper. Further, since copper easily diffuses into the polyimide film, nickel, chrome, silver, gold, tin or the like may be interposed as a barrier layer between the polyimide film and copper for the purpose of preventing diffusion of copper.

Hereinafter, examples will be described in detail. The polyimide film used in the examples is formed by the methods of Synthesis Examples 1 to 5, but is not limited thereto. The polyimide films used in Comparative Examples 1 and 2 were formed by the methods of Synthesis Examples 6 to 7. As the adhesives used in the examples, those which are combined according to Synthesis Examples 8 to 9 are used, but the present invention is not limited thereto. The film thickness, the linear expansion coefficient, the elastic modulus, the humidity expansion coefficient, the water absorption rate and the heat shrinkage ratio were measured by the following methods (1) to (6).

(1) film thickness

The measurement was carried out using Lightmatic (Series 318) manufactured by Mitutoyo Corporation.

(2) Coefficient of linear expansion

The measurement was carried out using TMA-50 manufactured by Shimadzu Corporation under the conditions of a measurement temperature range of 50 to 200 占 폚 and a temperature rise rate of 10 占 폚 / min.

(3) Elastic modulus

RTM-250 manufactured by A & D Corporation under the conditions of a tensile rate of 100 mm / min.

(4) Moisture expansion coefficient

The film was placed in a TM7000 furnace at 25 deg. C, and a dry gas was blown into the furnace to dry it. Then, the inside of the furnace was humidified at 90% RH by supplying air from the HC-1 type steam generator, The humidity expansion coefficient was determined.

(5) Absorption rate

The solution was allowed to stand in a desiccator under an atmosphere of 98% RH for 2 days, and was evaluated as an increase in weight% with respect to the weight upon drying.

(6) Heat shrinkage ratio

A film of 2 cm x 20 cm was prepared and the film dimension (L1) after being left in a room adjusted at 25 ° C and 60% RH for 2 days was measured. Subsequently, the film was heated at 200 ° C for 60 minutes, % RH for 2 days, and then the film dimension (L2) was measured and evaluated by the following formula.

Heat shrinkage ratio = - (L2-L1) / L1 100

(Synthesis Example 1)

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) / paraphenylmethane dianhydride (Molecular weight: 108.14) were mixed in a molar ratio of 3/1/3/1 and polymerized as a 18.5 wt% solution of DMAc (NN-dimethylacetamide) to obtain a polyamic acid. The phthalic anhydride (molecular weight: 102.09) and isoquinoline were mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, the amount of acetic anhydride and isoquinoline was 2.0 and 0.4 molar equivalents, respectively, with respect to the amide acid group of the polyamic acid. The obtained mixture was cast on a stainless steel drum rotating at 100 DEG C from a T-shaped slit die to obtain a gel film having a self-supporting property with a residual volatile component of 60 wt%. The gel film was peeled off from the drum and both ends thereof were held and processed in a heating furnace at 200 캜 for 30 seconds, 350 캜 for 30 seconds, and 550 캜 for 30 seconds to obtain a polyimide film having a thickness of 25 탆. The physical properties are shown in Table 1.

(Synthesis Example 2)

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) / paraphenylmethane dianhydride (Molecular weight: 108.14) were mixed in a molar ratio of 3/2/4/1 and polymerized as a 18.5 wt% solution of DMF (N, N-dimethylformamide) to obtain a polyamic acid. At this time, pyromellitic dianhydride and para-phenylenediamine were first reacted first, and then 4,4'-diaminodiphenyl ether and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Was added. The phthalic anhydride (molecular weight: 102.09) and isoquinoline were mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, the amount of acetic anhydride and isoquinoline was adjusted to 2.0 and 0.4 molar equivalents, respectively, based on the amide acid group of the polyamic acid. The resulting mixture was cast on a stainless steel drum rotating at 100 DEG C from a T-shaped slit die to obtain a gel film having a self-supporting property with a residual volatile component of 60 wt%. The gel film was peeled off from the drum, and both ends thereof were held and processed in a heating furnace at 200 캜 for 30 seconds, 350 캜 for 30 seconds, and 550 캜 for 30 seconds to obtain a polyimide film having a thickness of 12.5 탆. The physical properties are shown in Table 1.

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(Synthesis Example 4)

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride Water (molecular weight 322.20) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) / paraphenylenediamine (molecular weight 108.14) were mixed at a molar ratio of 119/39/2/120/40 to obtain DMAc (N , N-dimethylacetamide) as a polymerization initiator to obtain a polyamic acid. The phthalic anhydride (molecular weight: 102.09) and isoquinoline were mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. The amount of acetic anhydride and isoquinoline was 2.0 and 0.4 molar equivalents, respectively, with respect to the amidic acid groups of the polyamic acid. The obtained mixture was cast from a T-shaped slit die on an endless belt and heated by hot air at 50 캜 to obtain a gel film having a self-supporting property with a remaining volatile component of 60% by weight. The gel film was peeled off from the endless belt, and both ends thereof were gripped and treated in a heating furnace at 150 占 폚 for 30 seconds, 300 占 폚 for 30 seconds, 400 占 폚 for 20 seconds, and 550 占 폚 for 20 seconds, A mid-film was obtained. The physical properties are shown in Table 1.

(Synthesis Example 5)

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) / paraphenylmethane dianhydride (Molecular weight: 108.14) / metaphenylenediamine (molecular weight: 108.14) at a molar ratio of 75/25/79/19/2 to obtain a solution of 18.5 wt% of DMAc (N, N-dimethylacetamide) To obtain a polyamic acid. The phthalic anhydride (molecular weight 102.09) and isoquinoline were mixed and stirred at a ratio of 50% by weight based on the polyamic acid solution. At this time, the amount of acetic anhydride and isoquinoline was 2.0 and 0.4 molar equivalents, respectively, with respect to the amide acid group of the polyamic acid. The obtained mixture was cast from a T-shaped slit die on an endless belt and heated by hot air at 50 캜 to obtain a gel film having a self-supporting property with a remaining volatile component of 60% by weight. The gel film was peeled off from the endless belt and both ends thereof were held and treated in a heating furnace at 150 占 폚 for 30 seconds, 300 占 폚 for 30 seconds, 400 占 폚 for 20 seconds, and 550 占 폚 for 20 seconds, A mid-film was obtained. The physical properties are shown in Table 1.

(Synthesis Example 6)

(Molecular weight: 218.12) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) were mixed at a molar ratio of 1/1, and 18.5 wt% solution of DMAc (N, N-dimethylacetamide) To obtain a polyamic acid. The phthalic anhydride (molecular weight: 102.09) and isoquinoline were mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, the amount of acetic anhydride and isoquinoline was 2.0 and 0.4 molar equivalents, respectively, with respect to the amide acid group of the polyamic acid. The obtained mixture was cast from a T-shaped slit die on a rotating stainless steel drum at a temperature of 100 캜 to obtain a gel film having a self-supporting property with a residual volatile component of 60% by weight. The gel film was peeled off from the drum and both ends thereof were held and treated in a heating furnace at 200 占 폚 for 30 seconds, 350 占 폚 for 30 seconds, and 550 占 폚 for 30 seconds to obtain a polyimide film having a thickness of 25 占 퐉. The physical properties are shown in Table 1.

(Synthesis Example 7)

(Molecular weight: 218.12) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) were mixed at a molar ratio of 1/1, and 18.5 wt% solution of DMF (N, N-dimethylformamide) To obtain a polyamic acid. The phthalic anhydride (molecular weight: 102.09) and isoquinoline were mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, the amount of acetic anhydride and isoquinoline was adjusted to 2.0 and 0.4 molar equivalents, respectively, based on the amide acid group of the polyamic acid. The obtained mixture was cast from a T-shaped slit die on a rotating 1000 占 폚 stainless steel drum to obtain a gel film having a self-supporting property with the remaining volatile components of 60% by weight. The gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 占 폚 for 30 seconds, 350 占 폚 for 30 seconds, and 550 占 폚 for 30 seconds to obtain a polyimide film having a thickness of 12.5 占 퐉. The physical properties are shown in Table 1.

(Synthesis Example 8)

19 parts by weight of aluminum hydroxide " H-43 ", a product of Showa Denko K.K., 9 parts by weight of epoxy resin " Epicote " 828 by Yucca Shell Co., Ltd., phosphorus-containing epoxy resin FX279BEK , 3.5 parts by weight of a curing agent "4,4'-DDS" (4,4'-diaminodiphenylsulfone) manufactured by Sumitomo Chemical Co., Ltd., NBR "PNR-1H" 26 parts by weight were mixed with 200 parts by weight of methyl isobutyl ketone at 30 DEG C with stirring to obtain an adhesive solution.

(Synthesis Example 9)

9 parts by weight of an epoxy resin "Epicote" 834 manufactured by Yucca Shell Co., Ltd., 17 parts by weight of a phosphorus-containing epoxy resin "ZX-1548-3" manufactured by Totogasai Co., Ltd., 4,4'-DDS ", 26 parts by weight of NBR" PNR-1H "manufactured by JSR Corporation, 20 parts by weight of aluminum hydroxide" H-43 "manufactured by Showa Denko KK, 200 parts by weight of methyl ethyl ketone At 30 DEG C to obtain an adhesive solution.

(Example 1)

The polyimide film formed in Synthesis Example 1 was used, and the adhesive of Synthesis Example 8 was applied to one side of the polyimide film. The adhesive was then heated and dried at 150 占 폚 for 5 minutes to form an adhesive layer having a dry film thickness of 25 占 퐉, .

Using a copper-clad laminate "F-30VC1" for a flexible printed circuit manufactured by Nikkan Kogyo Co., Ltd., the adhesive layer of the copper foil and coverlay was bonded at 100 ° C and 0.27 MPa. The thus-bonded copper-clad laminate and coverlay were used to evaluate the peel strength (fill strength), solder heat resistance, and flame retardancy based on UL. The results are shown in Table 2.

(Comparative Example 1)

A coverlay was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 1 was changed to the polyimide film formed in Synthesis Example 6 in Example 1 and evaluated in the same manner as in Example 1 Respectively. The results are shown in Table 2.

(Example 2)

The polyimide film formed in Synthesis Example 2 was used, and the adhesive of Synthesis Example 9 was applied to this single side and heated and dried at 150 占 폚 for 5 minutes to form an adhesive layer having a dry film thickness of 15 占 퐉 to obtain a coverlay .

A copper-clad laminate "F-30VC1" for a flexible printed circuit manufactured by Nikkan Kogyo Co., Ltd. was used, and the adhesive layer of the copper foil and coverlay was bonded at 100 ° C and 0.27 MPa. The peel strength (peel strength), solder heat resistance, flame retardancy based on UL, and tackiness were evaluated by using the copper-clad laminate and coverlay thus bonded. The results are shown in Table 2.

(Comparative Example 2)

A coverlay was formed in the same manner as in Example 2 except that the polyimide film formed in Synthesis Example 2 was changed to the polyimide film formed in Synthesis Example 7 and the same evaluation as in Example 2 Respectively. The results are shown in Table 2.

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(Example 4)

A coverlay was formed in the same manner as in Example 2 except that the polyimide film formed in Synthesis Example 2 was changed to the polyimide film formed in Synthesis Example 4 and the same evaluation as in Example 2 Respectively. The results are shown in Table 2.

(Example 5)

A coverlay was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 1 was changed to the polyimide film formed in Synthesis Example 5 and the same evaluation as that of Example 2 Respectively. The results are shown in Table 2. <

Corresponding
Examples and
Comparative Example thickness
(탆) Linear expansion coefficient
(ppm / DEG C) Modulus of elasticity
(GPa) Humidity coefficient of expansion
(ppm /% RH) Absorption rate
(%) heating
Contraction ratio
(%) Synthesis Example 1 Example 1 25 12.1 6.5 15.9 1.8 0.02 Synthesis Example 2 Example 2 12.5 15.4 5.5 14.7 1.6 0.03 Synthesis Example 4 Example 4 12.5 13.1 6.5 15.8 1.8 0.02 Synthesis Example 5 Example 5 6.2 15.7 5.5 16.0 1.6 0.03 Synthesis Example 6 Comparative Example 1 25 25.2 3.5 24.0 2.9 0.25 Synthesis Example 7 Comparative Example 2 12.5 27.1 3.5 24.0 2.9 0.25

Peel strength (N / cm) Soldering heat resistance Flammability Example 1 15 280 UL94 V-O Example 2 14 280 UL94 V-O Example 4 12 280 UL94 V-O Example 5 12 280 UL94 V-O Comparative Example 1 4 250 UL94 VTM-O Comparative Example 2 5 250 UL94 VTM-O

Claims (4)

A mixture of paraphenylenediamine and 4,4'-diaminodiphenyl ether as diamine components, pyromellitic dianhydride as acid dianhydride component and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Wherein the polyimide film comprises 10-50 mol% of paraphenylenediamine, 50-90 mol% of 4,4'-diaminodiphenyl ether, 55-95 mol% of pyromellitic dianhydride, 3,3 ' Biphenyltetracarboxylic acid dianhydride is 5-45 mol%, the content of 4,4'- The polyimide film has a modulus of elasticity of 3 to 7 GPa, a linear expansion coefficient of 5 ppm / 占 폚 or more, less than 16 ppm / 占 폚 at 50 to 200 占 폚, a humidity expansion coefficient of 25 ppm / And a heat shrinkage rate at a time of 0.10% or less is used, and an adhesive layer is formed on one side of the polyimide film. delete delete The coverlay according to claim 1, wherein the adhesive is at least one selected from the group consisting of an epoxy resin, an acrylic resin and a polyimide resin.