JP2007180179A - Chip on film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip on film excellent in foldability and obtained by using a polyimide film having high dimensional stability and proper elastic modulus. <P>SOLUTION: The chip on film permits wiring 2 to be formed on at least one surface of a polyimide film 1 such that an IC chip is mountable thereon. The polyimide film 1 is obtained by using chiefly 3,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether as diamine components, and using pyromellitic dianhydride as dianhydride. The wiring 2 is formed on at least one surface of the polyimide film 1 via an adhesive or without mediating the same. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chip-on film (COF), and more particularly, to a chip-on film excellent in bendability using a polyimide film having a high elastic stability and an appropriate elastic modulus.

  As a substrate formed by bonding and mounting a semiconductor element on a flexible wiring substrate, there is a TAB (Tape Automated Bonding) tape. In this TAB tape, an opening penetrating in advance in the portion of the insulating tape where the semiconductor element is mounted is opened, and the tip portion of the wiring pattern and the semiconductor element are joined in a state where the wiring pattern protrudes in a cantilever shape. It has become so.

  As an insulating tape used for this TAB tape, a polyimide film is used. Particularly, since a high dimensional accuracy is required, a TAB tape using a polyimide film having low thermal expansion (for example, Patent Document 1). And 2) were known.

On the other hand, as with the TAB tape, as a substrate formed by bonding and mounting a semiconductor element on a flexible wiring board, an opening that penetrates to a portion where the semiconductor element is mounted in the insulating tape is not provided, A chip-on film in which a tip part of a wiring pattern provided on the surface of an insulating tape and a semiconductor element are bonded has been known. This chip-on film requires an insulating tape that can be bent freely for its intended purpose. However, although the above-mentioned polyimide film having low thermal expansibility is highly dimensionally stable, its elastic modulus is too high. It could not be suitable for the purpose of bending.
JP-A-5-148458 JP-A-10-70157

  The present invention has been achieved as a result of studying the solution of the problems in the prior art described above as an issue.

  Therefore, the objective of this invention is providing the chip-on film excellent in the bendability which uses the polyimide film which has moderate elasticity modulus with high dimensional stability.

  In order to achieve the above object, according to the present invention, a chip-on film is formed by forming wiring so that an IC chip can be mounted on at least one surface of a polyimide film, and the polyimide film is used as a diamine component. A polyimide film mainly composed of 3,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl ether, pyromellitic dianhydride as an acid dianhydride component, and an adhesive is provided on at least one surface of the polyimide film. A chip-on-film characterized in that the wiring is formed without any intervening, and a chip-on film, wherein the wiring is formed on at least one surface of the polyimide film via an adhesive. Provided.

In the chip on film of the present invention,
The polyimide film comprises 30 to 60 mol% 3,4'-diaminodiphenyl ether and 40 to 70 mol% 4,4'-diaminodiphenyl ether as a diamine component, and pyromellitic dianhydride as an acid dianhydride component. A polyimide film mainly used;
The polyimide film has an elastic modulus of 3 to 5 GPa, a linear expansion coefficient at 50 to 200 ° C. of 10 to 30 ppm / ° C., a humidity expansion coefficient of 25 ppm /% RH or less, a water absorption of 2.5% or less, and 200 ° C. for 1 hour. The heat shrinkage ratio of 0.10% or less,
The number of protrusions having a size of 20 μm or more present on the surface of the polyimide film is 10/5 cm × 5 cm or less,
The number of protrusions having a height of 2 μm or more present on the surface of the polyimide film is 10/5 cm × 5 cm or less,
The wiring is mainly made of copper;
The wiring is formed by etching a metal layer, the wiring is formed by plating, and the adhesive is at least one selected from an epoxy resin, an acrylic resin, and a polyimide resin It can be mentioned that preferable conditions are mainly composed of.

  According to the present invention, as described below, a chip-on film excellent in bendability using a polyimide film having high dimensional stability and an appropriate elastic modulus can be obtained.

  The present invention is described in detail below.

  1A is a plan view of an IC chip mounting portion showing an example of the chip-on film of the present invention, and FIG. 1B is a cross-sectional view taken along line (a)-(b) shown in FIG. 1A. It is.

  As shown in FIG. 1, the chip-on film of the present invention uses a polyimide film 1 as a base material, and provides a chip mounting portion 3 so that an IC chip can be mounted on the polyimide film 1. Wiring (for example, inner leads) 2 is formed on one side or both sides.

  Here, after plating the surface of the inner lead 2 with Au, Sn or the like, the IC chip provided with a plurality of metal bumps such as Au or Sn is joined. At this time, the inner lead 2 and bumps such as Au and Sn are heated to a solid-phase bonding and eutectic bonding temperature of about 300 to 500 ° C., and a suitable total load is applied in a lump using a bonding tool, and the inner lead 2 and Au, Sn are heated. Bumps such as heat and pressure are bonded. Thereby, solid phase bonding and eutectic bonding can be performed, and the inner lead 2 and the bumps of Au, Sn, etc. can be electrically connected, and a chip-on film can be obtained.

  In the chip-on film of the present invention, the polyimide film used as a substrate is mainly composed of 3,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl ether as the diamine component, and pyromellitic dianhydride as the acid dianhydride component. It is the polyimide film which becomes. That is, three types of 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, and pyromellitic dianhydride are essential components, and only these three types or a small amount of another component is added to these three types. It is a polyimide film obtained by this. Preferably, 30 to 60 mol% of 3,4′-diaminodiphenyl ether and 40 to 70 mol% of 4,4′-diaminodiphenyl ether are used as the diamine component, and pyromellitic dianhydride is used as the acid dianhydride component. It is the polyimide film which becomes. More preferably, the elastic modulus is 3 to 5 GPa, the linear expansion coefficient at 50 to 200 ° C. is 10 to 30 ppm / ° C., the humidity expansion coefficient is 25 ppm /% RH or less, the water absorption is 2.5% or less, and 200 ° C. for 1 hour. Is a polyimide film having a heat shrinkage of 0.10% or less.

  In the diamine component of the polyimide film, if there is too much 3,4'-diaminodiphenyl ether, it will be hard, and if it is too little, it will be too soft, so it is preferably 30-60 mol%, more preferably 35-55 mol%, more preferably 40- 50 mol%. When the amount of 4,4'-diaminodiphenyl ether is too much, it becomes soft, and when it is too little, it becomes hard, so it is preferably 40 to 70 mol%, more preferably 45 to 65 mol%, more preferably 50 to 60 mol%.

  The elastic modulus, which is an index of the hardness of the polyimide film, is preferably in the range of 3 to 5 GPa. If it exceeds 5 GPa, it is too hard and if it is less than 3 GPa, it is too soft. The linear expansion coefficient is preferably 10 to 30 ppm / ° C., and if it exceeds 30 ppm / ° C., the dimensional change due to heat is too large, and if it is smaller than 10 ppm / ° C., the difference from the linear expansion coefficient with the metal used for wiring increases. Therefore, warping occurs. When the humidity expansion coefficient exceeds 25 ppm /% RH, the dimensional change due to humidity is too large. Therefore, the humidity expansion coefficient is preferably 25 ppm /% RH or less. If the water absorption rate exceeds 2.5%, the dimensional change of the film becomes large due to the influence of the sucked water, so 2.5% or less is preferable. When the heat shrinkage rate at 200 ° C. for 1 hour exceeds 0.10%, the dimensional change due to heat 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 of the present invention in addition to 3,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether. In addition to pyromellitic dianhydride, a small amount of acid dianhydride may be added. Specific examples of diamines and acid dianhydrides include, but are not limited to:

(1) Acid dianhydride 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4 4′-benzophenone tetracarboxylic dianhydride, 2,3,6,7-naphthalenedicarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5 6-tetracarboxylic dianhydride, 1,2,4,5-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 1,4,5,8-deca Hydronaphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,5,6-hexahydronaphthalenetetracarboxylic dianhydride, 2,6-dichloro-1,4,5,8-naphthalenetetracarboxylic Acid dianhydride, 2,7-dichloro B-1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-tetrachloro-1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,8,9 , 10-phenanthrenetetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, , 1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, bis ( 3,4-dicarboxyphenyl) sulfone dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, 3,4,3 ′, 4′-benzophenone tetracarboxylic dianhydride, and the like.

(2) Diamine 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, metaphenylenediamine, 4,4′-diaminodiphenylpropane, 3,4′-diaminodiphenylpropane, 3,3′-diaminodiphenylpropane 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, benzidine, 4,4'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 3,3'- Diaminodiphenyl sulfide, 4,4′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, 3,3′-diaminodiphenylsulfone, 2,6-diaminopyridine, bis- (4-aminophenyl) diethylsilane, 3, , 3'-Dichlorobenzidine Bis- (4-aminophenyl) ethylphosphinoxide, bis- (4-aminophenyl) phenylphosphinoxide, bis- (4-aminophenyl) -N-phenylamine, bis- (4-aminophenyl) ) -N-methylamine, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-dimethyl-3 ', 4-diaminobiphenyl 3,3'-dimethoxybench Gin, 2,4-bis (p-β-amino-t-butylphenyl) ether, bis (p-β-amino-t-butylphenyl) ether, p-bis (2-methyl-4-aminopentyl) benzene P-bis- (1,1-dimethyl-5-aminopentyl) benzene, m-xylylenediamine, p-xylylenediamine, 1,3-diaminoadamantane, 3, '-Diamino-1,1'-diaminoadamantane, 3,3'-diaminomethyl 1,1'-diadamantane, bis (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylene Diamine, decamethylenediamine, 3-methylheptamethylenediamine, 4,4'-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine 3-methoxyhexaethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4-diaminocyclohexane, 1,12-diaminooctadecane, 2,5- Diamino-1,3 , 4-oxadiazole, 2,2-bis (4-aminophenyl) hexafluoropropane, N- (3-aminophenyl) -4-aminobenzamide, 4-aminophenyl-3-aminobenzoate and the like.

  In the present invention, specific examples of the organic solvent used for forming the polyamic acid solution include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide and the like. Formamide solvents, N, N-dimethylacetamide, acetamide solvents such as N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, Examples thereof include phenolic solvents such as m- or p-cresol, xylenol, halogenated phenol and catechol, or aprotic polar solvents such as hexamethylphosphoramide and γ-butyrolactone, and these may be used alone or as a mixture. It is desirable to use But further xylene, the use of aromatic hydrocarbons such as toluene are also possible.

The polymerization method of polyimide may be performed by any known method, for example,
(1) A method in which the entire amount of the aromatic diamine component is first put in a solvent, and then the aromatic tetracarboxylic acid component is added so as to be equivalent to the total amount of the aromatic diamine component and polymerized.
(2) A method in which the whole amount of the aromatic tetracarboxylic acid component is first put in a solvent, and then the aromatic diamine component is added in an amount equal to the amount of the aromatic tetracarboxylic acid component for polymerization.
(3) After one aromatic diamine compound is put in a solvent, the aromatic tetracarboxylic acid compound is mixed with the reaction component at a ratio of 95 to 105 mol% for the time required for the reaction, A method in which an aromatic diamine compound is added, and then an aromatic tetracarboxylic acid compound is added and polymerized so that the total aromatic diamine component and the total aromatic tetracarboxylic acid component are approximately equal.
(4) After placing the aromatic tetracarboxylic acid compound in the solvent, the aromatic tetracarboxylic acid compound is mixed for a time required for the reaction at a ratio of 95 to 105 mol% of one aromatic diamine compound with respect to the reaction component, and then the aromatic tetracarboxylic acid compound is mixed. A method in which a carboxylic acid compound is added, and then the other aromatic diamine compound is added and polymerized so that the total aromatic diamine component and the total aromatic tetracarboxylic acid component are approximately equal.
(5) A polyamic acid solution (A) is prepared by reacting one aromatic diamine component with an aromatic tetracarboxylic acid in a solvent so that either one becomes excessive, and the other aromatic diamine in another solvent. The polyamic acid solution (B) is prepared by reacting the component and the aromatic tetracarboxylic acid so that either one becomes excessive. A method of mixing the polyamic acid solutions (A) and (B) thus obtained to complete the polymerization. At this time, when adjusting the polyamic acid solution (A), if the aromatic diamine component is excessive, the polyamic acid solution (B) contains excessive aromatic tetracarboxylic acid component, and the polyamic acid solution (A) contains aromatic tetracarboxylic acid. When the acid component is excessive, the polyamic acid solution (B) makes the aromatic diamine component excessive, and the polyamic acid solutions (A) and (B) are combined to form the wholly aromatic diamine component and wholly aromatic compound used in these reactions. Adjustment is made so that the amount of the tetracarboxylic acid component is approximately equal.

  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 its viscosity is 10 to 2000 Pa · s as measured by a Brookfield viscometer, preferably 100-1000 Pa · s is preferably used for stable liquid feeding. Moreover, the polyamic acid in the organic solvent solution may be partially imidized.

  Next, the manufacturing method of the polyimide film of this invention is demonstrated.

  As a method for forming a polyimide film, a polyamic acid solution is cast into a film and thermally decyclized and desolvated to obtain a polyimide film, and a polyamic acid solution is mixed with a cyclization catalyst and a dehydrating agent. The method of obtaining a polyimide film by preparing a gel film by decyclization and heating it to remove the solvent is mentioned, but the latter is preferable because the linear expansion coefficient of the obtained polyimide film can be kept low. .

  Furthermore, various fillers such as silica and alumina may be added for the purpose of improving the slipperiness of the film. As the particle size of the filler to be used, it is preferable to use those having an average particle size of 0.1 to 1 μm. If the average particle size is less than 0.1 μm, the slipperiness of the film is poor, and if the average particle size exceeds 1 μm, many agglomerates are present during film production. Furthermore, when a filler having an average particle diameter of 1 μm or more is used, the number of protrusions having a size of 20 μm or more existing on the film surface is larger than 10/5 cm × 5 cm, and the number of protrusions having a height of 2 μm or more is ten. / 5cm × 5cm. This size of convexity will cause problems such as causing a conduction failure across the filler between the wirings, and causing a problem of breaking through the film thickness of the photoresist mask. It is desirable to control so that the number of projections having a size of 20 μm or more existing on the surface is 10/5 cm × 5 cm or less and the number of projections having a height of 2 μm or more is 10/5 cm × 5 cm or less.

  Although it does not specifically limit about the thickness of a polyimide film, Preferably it is 1-225 micrometers, More preferably, it is 5-175 micrometers. When it is too thick, it becomes easy to cause winding slip when it is made into a roll, and when it is too thin, wrinkles and the like are likely to enter.

  Wiring is formed on one side or both sides of the polyimide film as described above so that an IC chip can be mounted via an adhesive or without an adhesive to form the chip-on film of the present invention.

  As an adhesive in the case of using an adhesive, at least one selected from an epoxy resin, an acrylic resin, and a polyimide resin is preferable. Among these, epoxy resins and polyimide resins are particularly preferable. These adhesives may be provided with various rubbers, plasticizers, curing agents, phosphorus-based flame retardants, and other various additives for the purpose of imparting flexibility. The polyimide resin is mainly thermoplastic polyimide, but may be thermosetting polyimide. In the case of a polyimide resin, a solvent is usually unnecessary, but a polyimide soluble in an appropriate organic solvent may be used.

  Examples of the wiring formation method include a subtractive method, a semi-additive method, a full additive method, and the like. The subtractive method is a method in which a copper foil is applied on a polyimide film via an adhesive, or a copper layer is formed by a plating method without using an adhesive, and then copper is etched into a wiring pattern. Means the method of forming. In this case, rolled copper foil or electrolytic copper foil is used as the copper foil. Also, when forming wiring, a photoresist layer is usually formed on a copper foil, and this photoresist layer is subjected to selective exposure and development to be patterned into a wiring shape, and the patterned photoresist layer is used as an etching mask. The copper is etched and then the photoresist layer is completely removed. Here, 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 etchant.

  In the semi-additive method, a metal layer to be a seed layer is first formed directly on a polyimide film or via an adhesive, a photoresist layer is formed on the seed layer, and the photoresist layer is selectively exposed and developed. By patterning into a wiring shape by processing, using the patterned photoresist layer as a plating mask, wiring is formed on the seed layer by electroless plating or electrolytic plating, and then the photoresist is completely removed, and finally other than wiring This means that the seed layer is removed by etching. Here, as the seed layer metal, nickel, chromium, aluminum, lead, copper, tin, zinc, iron, silver, gold or the like is used alone or as an alloy. In addition, a liquid or dry film resist is used as a photoresist, lead, copper, nickel, chromium, tin, zinc, silver, gold or the like is used as a metal for electroless plating or electrolytic plating, and as an etching solution, An etchant that matches the metal of the seed layer is used.

  In the full additive method, a photoresist layer is formed directly on a polyimide film or on an adhesive, and the photoresist layer is subjected to selective exposure and development to pattern it into a wiring, and the patterned photoresist layer is plated. It means a method of forming a wiring by electroless plating as a mask and then completely removing the photoresist. Here, a liquid or dry film resist is used as the photoresist, and copper, nickel, lead, chromium, tin, zinc, silver, gold or the like is used as the electroless plating metal.

  As a metal used for the above-mentioned various wiring formation methods, copper is mainly preferred.

  The formed wiring is used as an electric / electronic circuit, but a metal having a higher resistance than copper is not preferable because electric conductivity is deteriorated. In addition, a metal having a density lower than that of copper is not preferable because electric conductivity is deteriorated. However, since copper also has the disadvantage of being easily rusted and corroded, it is optional to form a metal such as tin, lead, aluminum, nickel, silver, or gold on copper for the purpose of protecting copper. . Also, since copper easily diffuses into the polyimide film, nickel, chromium, silver, gold, tin, or the like can be arbitrarily placed as a barrier layer between the polyimide film and copper in order to prevent copper diffusion. .

  The chip-on film of the present invention thus configured is a variety of IC chips that have extremely high bendability due to the use of a polyimide film having an appropriate elastic modulus with high dimensional stability and requires fine wiring. It can be preferably applied to mounting applications.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  In addition, although the polyimide film used by the Example uses what was formed into a film by the method of the synthesis examples 1-6, it is not limited to these. Moreover, what was formed into a film by the synthesis examples 7-8 is used for the polyimide film used by Comparative Examples 1-2. Furthermore, as the adhesive used in the examples, those prepared in Synthesis Examples 9 to 10 are used, but are not limited thereto.

  Moreover, each characteristic of the polyimide film obtained by the synthesis example was evaluated by the following method.

(1) Film thickness It measured using the lightmatic (Series318) made from Mitutoyo.

(2) Linear expansion coefficient TMA-50 manufactured by Shimadzu Corporation was used, and measurement was performed under the conditions of a measurement temperature range: 50 to 200 ° C and a temperature increase rate: 10 ° C / min.

(3) Elastic modulus RTM-250 manufactured by A & D was used, and measurement was performed under the condition of a tensile speed of 100 mm / min.

(4) Humidity expansion coefficient A film was installed in a TM7000 furnace at 25 ° C., dried by sending dry gas into the furnace, and then the inside of the TM7000 furnace was 90% RH by supplying air from an HC-1 type steam generator. The humidity expansion coefficient was determined from the dimensional change during the period.

(5) Water absorption rate It left still in the desiccator of 98% RH atmosphere for 2 days, and evaluated by the weight increase with respect to the weight at the time of drying.

(6) Heat shrinkage rate A film of 20 cm × 20 cm was prepared, and the film size (L1) after being left in a room adjusted to 25 ° C. and 60% RH for 2 days was measured, followed by heating at 200 ° C. for 60 minutes. Thereafter, the film size (L2) was measured after being left in a room adjusted to 25 ° C. and 60% RH for 2 days, and evaluated by the following formula calculation.
Heat shrinkage rate = − (L2−L1) / L1 × 100

(Synthesis Example 1)
Pyromellitic dianhydride (molecular weight 218.12) / 3,4′-diaminodiphenyl ether (molecular weight 200.24) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) in a molar ratio of 5/2/3 The polymer was prepared at a ratio of 18.5 wt% in DMAc (N, N-dimethylacetamide) and polymerized to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a 100 ° C. stainless steel drum rotated from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.20 mm. This gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, and 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 25 μm. The physical properties are shown in Table 1.

(Synthesis Example 2)
Pyromellitic dianhydride (molecular weight 218.12) / 3,4′-diaminodiphenyl ether (molecular weight 200.24) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) in a molar ratio of 5/2/3 The polymer was prepared at a ratio of 18.5 wt% in DMAc (N, N-dimethylacetamide) and polymerized to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a 100 ° C. stainless steel drum rotated by a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.30 mm. This gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, and 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 38 μm. The physical properties are shown in Table 1.

(Synthesis Example 3)
Pyromellitic dianhydride (molecular weight 218.12) / 3,4′-diaminodiphenyl ether (molecular weight 200.24) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) in a molar ratio of 2/1/1 The polymer was prepared at a ratio of 18.5 wt% in DMAc (N, N-dimethylacetamide) and polymerized to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a 100 ° C. stainless steel drum rotated from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.20 mm. This gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, and 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 25 μm. The physical properties are shown in Table 1.

(Synthesis Example 4)
Pyromellitic dianhydride (molecular weight 218.12) / 3,4′-diaminodiphenyl ether (molecular weight 200.24) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) in a molar ratio of 2/1/1 The polymer was prepared at a ratio of 18.5 wt% in DMAc (N, N-dimethylacetamide) and polymerized to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a stainless steel drum rotated at 100 ° C. from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.10 mm. The gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 12.5 μm. . The physical properties are shown in Table 1.

(Synthesis Example 5)
Pyromellitic dianhydride (molecular weight 218.12) / 3,4′-diaminodiphenyl ether (molecular weight 200.24) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) in a molar ratio of 100/45/55 The polymer was prepared at a ratio of 18.5 wt% in DMAc (N, N-dimethylacetamide) and polymerized to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a 100 ° C. stainless steel drum rotated by a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.07 mm. This gel film was peeled off from the drum, both ends thereof were gripped, and treated in a heating furnace at 200 ° C. × 30 seconds, 350 ° C. × 30 seconds, 550 ° C. × 30 seconds to obtain a 9 μm-thick polyimide film. The physical properties are shown in Table 1.

(Synthesis Example 6)
Pyromellitic dianhydride (molecular weight 218.12) / 3,4′-diaminodiphenyl ether (molecular weight 200.24) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) in a molar ratio of 100/55/45 The polymer was prepared at a ratio of 18.5 wt% in DMAc (N, N-dimethylacetamide) and polymerized to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a stainless steel drum at 100 ° C. rotated by a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.05 mm. This gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, and 550 ° C. for 30 seconds to obtain a 6 μm thick polyimide film. The physical properties are shown in Table 1.

(Synthesis Example 7)
Pyromellitic dianhydride (molecular weight 218.12) / 4,4′-diaminodiphenyl ether (molecular weight 200.20) is mixed in a molar ratio of 50/50 to obtain DMF (N, N-dimethylformamide) 18. Polymerization was performed with a 5 wt% solution to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a 100 ° C. stainless steel drum rotated from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.20 mm. This gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, and 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 25 μm. The physical properties are shown in Table 1.

(Synthesis Example 8)
Pyromellitic dianhydride (molecular weight 218.12) / 4,4′-diaminodiphenyl ether (molecular weight 200.20) is mixed in a molar ratio of 50/50 to obtain DMF (N, N-dimethylformamide) 18. Polymerization was performed with a 5 wt% solution to obtain 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a stainless steel drum rotated at 100 ° C. from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.10 mm. The gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 12.5 μm. . The physical properties are shown in Table 1.

(Synthesis Example 9)
Prepare pyromellitic dianhydride (molecular weight 218.12) / 4,4'-diaminodiphenyl ether (molecular weight 200.20) / paraphenylenediamine (molecular weight 108.14) at a molar ratio of 100/15/85. And polymerized to a 18.5 wt% solution in DMAc (N, N-dimethylacetamide) to give 3000 poise polyamic acid. A conversion agent consisting of acetic anhydride (molecular weight 102.09) and isoquinoline was mixed and stirred at a ratio of 50% by weight to the polyamic acid solution. At this time, it prepared so that acetic anhydride and isoquinoline might be 2.0 and 0.4 molar equivalent with respect to the amic acid group of a polyamic acid, respectively. The obtained mixture was cast on a 100 ° C. stainless steel drum rotated from a T-shaped slit die to obtain a gel film having a self-supporting property of 55% by weight of residual volatile components and a thickness of about 0.20 mm. This gel film was peeled off from the drum, and both ends thereof were gripped and treated in a heating furnace at 200 ° C. for 30 seconds, 350 ° C. for 30 seconds, and 550 ° C. for 30 seconds to obtain a polyimide film having a thickness of 25 μm. The physical properties are shown in Table 1.

(Synthesis Example 10)
50 parts by weight of epoxy resin “Epicoat” 834 manufactured by Yuka Shell Co., Ltd., 100 parts by weight of phosphorus-containing epoxy resin FX279BEK75 manufactured by Tohto Kasei Co., Ltd., 6 weights of curing agent 4,4′-DDS manufactured by Sumitomo Chemical Co., Ltd. Part, JSR Co., Ltd. NBR (PNR-1H) 100 parts by weight, Showa Denko Co., Ltd. 30 parts by weight aluminum hydroxide was stirred and mixed with methyl isobutyl ketone 600 parts by weight at 30 ° C. to obtain an adhesive solution. .

Example 1
The polyimide film formed in Synthesis Example 1 was used, the vacuum chamber was brought to an ultimate pressure of 1 × 10 −3 Pa, and nickel / chromium = 95/5 (weight ratio) by DC magnetron sputtering at an argon gas pressure of 1 × 10 −1 Pa. The Nichrome alloy (1) was sputtered on one side to a thickness of 5 nm, and copper was further sputtered to a thickness of 50 nm. Next, a copper layer having a thickness of 6 μm was laminated by electrolytic plating using a copper sulfate bath under the condition of a current density of 2 A / dm 2 to prepare a single-sided flexible copper-clad plate. The composition of the copper sulfate bath was a solution in which an appropriate amount of additives was added to copper sulfate pentahydrate 80 g / liter, sulfuric acid 200 g / liter, and hydrochloric acid 50 mg / liter.

Using the obtained copper-clad plate, a photoresist AZP4620 made by Clariant Japan Co., Ltd. was formed on a single-sided copper foil with a film thickness of 5 μm after drying at 105 ° C. for 10 minutes, and the line width / space width = 15 μm / 15 μm Exposure is performed at 400 mJ / cm ² (full wavelength) using a glass photomask in which a pattern is arranged and inner leads for bonding IC chips as shown in FIG. 1 are arranged, AZ400K / water = 25/75 The photoresist was patterned by developing with a developer (by weight). Then, copper etching was performed at 40 ° C. for 90 seconds using a 30 wt% aqueous solution of iron chloride to remove the copper where the photoresist was not formed. After the copper etching was completed, the photoresist was peeled off at 40 ° C. for 1 minute using a 2.5 wt% sodium hydroxide aqueous solution. In this way, a circuit pattern for chip-on-film with line / space = 15/15 μm was formed on one side.

  A bending test was performed using the wiring board patterned for the chip-on-film thus obtained. First, the wiring board was sampled to a width of 48 mm × 10 cm, and then a sample was set on an MIT testing machine (testing machine described in JIS-P-8115). A load of 9.8 N, a radius of curvature of 0.38 mm, and a bending repetition rate of 10 I went there. At this time, the mounting of the sample was adjusted so that the inner lead came to the bent portion. The inner lead after the bending test was observed for wrinkling. The results are shown in Table 2.

Further, the dimension in the TD direction of the wiring board was measured (L3), then immersed in a 300 ° C. solder bath for 20 seconds, and after the immersion, the dimension in the TD direction was measured again (L4). The dimensional change rate before and after the treatment with the solder bath was determined by the following formula.
Dimensional change rate (%) = (L4−L3) / L3 × 100

  The dimensional results are shown in Table 2.

(Example 2)
A circuit pattern for a chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 2 was used. Table 2 shows the dimensional change rate results before and after the treatment.

(Example 3)
A circuit pattern for a chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 3 was used. Table 2 shows the dimensional change rate results before and after the treatment.

Example 4
A circuit pattern for chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 4 was used. Table 2 shows the dimensional change rate results before and after the treatment.

(Example 5)
A circuit pattern for a chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 5 was used. Table 2 shows the dimensional change rate results before and after the treatment.

(Example 6)
A circuit pattern for chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 6 was used. Table 2 shows the dimensional change rate results before and after the treatment.

(Example 7)
Using the polyimide film formed in Synthesis Example 1, the adhesive of Synthesis Example 10 was applied to one side of the polyimide film and dried by heating at 150 ° C. for 5 minutes to form an adhesive layer having a dry film thickness of 10 μm. This polyimide film with a single-sided adhesive and 1/2 ounce copper foil (manufactured by Nikko Gould Foil Co., Ltd., JTC foil) were laminated at a laminating temperature of 160 ° C. and a laminating pressure of 196 N / cm (20 kgf / cm) using a hot roll laminator. cm) and laminating speed of 1.5 m / min, thermal lamination was performed to prepare a single-sided copper-clad plate.

Using the obtained copper-clad plate, a photoresist AZP4620 manufactured by Clariant Japan Co., Ltd. was formed on a single-sided copper foil with a film thickness of 10 μm after drying at 105 ° C. for 10 minutes, and the line width / space width = 15 μm / 15 μm Exposure is performed at 400 mJ / cm ² (full wavelength) using a glass photomask in which a pattern is arranged and inner leads for bonding IC chips as shown in FIG. 1 are arranged, AZ400K / water = 25/75 The photoresist was patterned by developing with a developer (by weight). Then, copper etching was performed at 40 ° C. for 90 seconds using a 30 wt% aqueous solution of iron chloride to remove the copper where the photoresist was not formed. After the copper etching was completed, the photoresist was peeled off at 40 ° C. for 1 minute using a 2.5 wt% sodium hydroxide aqueous solution. In this way, a circuit pattern for chip-on-film with line / space = 15/15 μm was formed on one side.

  A bending test was performed using the wiring board patterned for the chip-on-film thus obtained. First, the wiring board was sampled to a width of 48 mm × 10 cm, and then a sample was set on an MIT testing machine (testing machine described in JIS-P-8115). A load of 9.8 N, a radius of curvature of 0.38 mm, and a bending repetition rate of 10 I went there. At this time, the mounting of the sample was adjusted so that the inner lead came to the bent portion. The inner lead after the bending test was observed for wrinkling. The results are shown in Table 2.

Further, the dimension in the TD direction of the wiring board was measured (L3), then immersed in a 300 ° C. solder bath for 20 seconds, and after the immersion, the dimension in the TD direction was measured again (L4). The dimensional change rate before and after the treatment with the solder bath was determined by the following formula.
Dimensional change rate (%) = (L4−L3) / L3 × 100

  The dimensional results are shown in Table 2.

(Comparative Example 1)
A circuit pattern for a chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 7 was used. Table 2 shows the dimensional change rate results before and after the treatment.

(Comparative Example 2)
A circuit pattern for a chip-on film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 8 was used. Table 2 shows the dimensional change rate results before and after the treatment.

(Comparative Example 3)
A circuit pattern for a chip-on-film was formed in the same manner as in Example 1 except that the polyimide film formed in Synthesis Example 9 was used. Table 2 shows the dimensional change rate results before and after the treatment.

  The chip-on film of the present invention is extremely excellent in bendability because it uses a polyimide film having an appropriate elastic modulus with high dimensional stability, and is preferable for various IC chip mounting applications that require fine wiring. Can be applied.

(A) is a top view of the IC chip mounting part which shows an example of the chip-on film of this invention, (B) is sectional drawing along the (a)-(b) line | wire shown to (A).

Explanation of symbols

1 ... polyimide film 2 ... wiring (inner lead)
3 ... IC chip mounting part

Claims (10)

A chip-on film in which wiring is formed so that an IC chip can be mounted on at least one surface of a polyimide film, and the polyimide film has 3,4′-diaminodiphenyl ether and 4,4′-diamino as diamine components. A polyimide film mainly comprising diphenyl ether and pyromellitic dianhydride as an acid dianhydride component, wherein the wiring is formed on at least one surface of the polyimide film without using an adhesive. Chip-on film. A chip-on film in which wiring is formed so that an IC chip can be mounted on at least one surface of a polyimide film, and the polyimide film has 3,4′-diaminodiphenyl ether and 4,4′-diamino as diamine components. It is a polyimide film mainly using diphenyl ether and pyromellitic dianhydride as an acid dianhydride component, and the wiring is formed on at least one surface of the polyimide film via an adhesive. Chip on film. The polyimide film comprises 30 to 60 mol% 3,4'-diaminodiphenyl ether and 40 to 70 mol% 4,4'-diaminodiphenyl ether as a diamine component, and pyromellitic dianhydride as an acid dianhydride component. The chip-on film according to claim 1, wherein the chip-on film is a polyimide film mainly used. The polyimide film has an elastic modulus of 3 to 5 GPa, a linear expansion coefficient at 50 to 200 ° C. of 10 to 30 ppm / ° C., a humidity expansion coefficient of 25 ppm /% RH or less, a water absorption of 2.5% or less, and 200 ° C. for 1 hour. The chip-on film according to any one of claims 1 to 3, wherein the heat shrinkage ratio of the film is 0.10% or less. 5. The chip-on film according to claim 1, wherein the number of projections having a size of 20 μm or more present on the surface of the polyimide film is 10/5 cm × 5 cm or less. The chip-on film according to claim 1, wherein the number of projections having a height of 2 μm or more present on the surface of the polyimide film is 10/5 cm × 5 cm or less. The chip-on film according to claim 1, wherein the wiring is mainly made of copper. The chip-on film according to claim 1, wherein the wiring is formed by etching a metal layer. The chip-on film according to claim 1, wherein the wiring is formed by plating. The chip-on film according to claim 2, wherein the adhesive mainly comprises at least one selected from an epoxy resin, an acrylic resin, and a polyimide resin.

Images