JP2008208255A - Chip-on-film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chip-on-film having moderate modulus in combination with high dimensional stability and also having excellent slipperiness and bendability, and adaptable to the automatic optical inspection (AOI) system. <P>SOLUTION: The chip-on-film has a wiring formed on at least one side of a polyimide film so as to mount IC chips. In this chip-on-film, the polyimide film is composed mainly of 3,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether as diamine components and pyrromellitic dianhydride as an acid dianhydride component, and 0.1-0.9 wt.%, per film resin weight of inorganic particles being 0.01-1.5 μm in size with an average size of 0.05-0.7 μm and having such a size distribution that particles 0.15-0.60 μm in size account for 80 vol.% or greater of the total particles are dispersed in the polyimide film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a chip-on film having high dimensional stability and appropriate elastic modulus, excellent slipperiness and bendability, and adaptable to an automatic optical inspection system (AOI).

  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.

Furthermore, the slipperiness (slidability) of a film is mentioned as an important practical characteristic of a polyimide film. That is, in various film processing steps, the film support (for example, roll) and the slipperiness of the film, and the slipperiness between the films are secured, thereby improving the operability and handleability in each step. Has the effect of avoiding the occurrence of defects such as wrinkles on the film. As an easy lubrication technique in a conventional polyimide film, an inert inorganic compound (for example, alkaline earth metal orthophosphate, dicalcium phosphate anhydrate, calcium pyrophosphate, silica, talc, etc.) is added to polyamic acid (patent) A method of performing plasma treatment after forming fine protrusions on the film surface with fine particles (see Patent Document 4) is known. However, there is a problem that the particles shown in these figures have a large particle size and cannot be applied to an automatic optical inspection system. In addition, the surface layer of the film has a large number of protrusions made of the inorganic particles, in which inorganic particles having an average particle diameter of 0.01 to 100 μm are held by embedding a part of each particle on the polyimide surface layer. There is known a method (see Patent Document 5) in which 1 × 10 to 5 × 10 ⁸ pieces / mm ² are present in the substrate. This method effectively obtains a slippery effect by positively exposing protrusions on the surface and reducing the coefficient of friction on the film surface, but the film is partially exposed because inorganic particles are partially exposed. There was a problem that the surface was scratched and the appearance was poor.
JP-A-5-148458 JP-A-10-70157 JP-A-62-68852 JP 2000-191810 A Japanese Patent Laid-Open No. 5-25295

  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.

  That is, an object of the present invention is to provide a chip-on film having high dimensional stability and moderate elastic modulus, excellent slipperiness and bendability, and adaptable to an automatic optical inspection system (AOI). There is to do.

  The present invention employs the following means in order to solve such problems.

  That is, the chip-on film of the present invention is a chip-on film in which wiring is formed on at least one surface of a polyimide film so that an IC chip can be mounted. -Diaminodiphenyl ether and 4,4'-diaminodiphenyl ether are mainly composed of pyromellitic dianhydride as the acid dianhydride component, and the polyimide film has a particle size of 0.01 Inorganic particles having a particle size distribution in which particles having an average particle size of 0.05 to 0.7 μm and particles having a particle size of 0.15 to 0.60 μm account for 80% by volume or more of all particles. Is dispersed and contained at a ratio of 0.1 to 0.9% by weight per film resin weight, and the wiring is connected. Agent without passing through either or adhesive through, and is characterized in that it is formed on at least one surface of the polyimide film.

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 8 GPa, a linear expansion coefficient at 50 to 200 ° C. of 5 to 20 ppm / ° C., a humidity expansion coefficient of 25 ppm /% RH or less, and a water absorption of 3.5% or less. And the heat shrinkage at 200 ° C. for 1 hour is 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 1 piece / 40 cm square or less,
The number of protrusions having a height of 2 μm or more present on the surface of the polyimide film is 5 pieces / 40 cm square or less,
The wiring is mainly made of copper;
The wiring is formed by etching a metal layer;
The wiring is formed by plating;
The adhesive is made of at least one selected from an epoxy resin, an acrylic resin, and a polyimide resin;
Are mentioned as preferable conditions.

  According to the present invention, there is provided a chip-on film that has high dimensional stability and appropriate elastic modulus, excellent slipperiness and bendability, and can be applied to an automatic optical inspection system (AOI). can do.

  The present invention is a diligent study on the above-mentioned problem, that is, a chip-on film that can be applied to an automatic optical inspection system (AOI) having an appropriate elastic modulus as well as high dimensional stability and having excellent slipperiness and bendability. When a specific amount of inorganic fine particles are dispersed and contained in a specific polyimide film composed of a specific “diamine component” as a polyimide constituent component, specific surface protrusions can be generated, and this is required. It was clarified to solve the problem at once.

  The present invention is described in detail below.

1A is a plan view of an IC chip mounting portion showing an example of the structure of the chip-on-film of the present invention, and FIG. 1B is a line (a)-(b) shown in FIG. 1A. FIG.
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 wiring 2 with Au, Sn or the like, an IC chip provided with a plurality of metal bumps such as Au or Sn is joined. At this time, the wiring 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. Bumps such as heat and pressure are bonded. Thereby, solid phase bonding and eutectic bonding are performed, and the wiring 2 and bumps such as Au and Sn 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 the substrate uses 3,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl ether as the diamine component. By this combination, a polyimide film having high dimensional stability can be obtained without using a rigid diamine such as paraphenylenediamine. That is, since a rigid diamine is not used, it is possible to obtain both a flexibility and a dimensional stability, and a polyimide film having a stable film forming property can be obtained. It is a specific polyimide film mainly composed of pyromellitic dianhydride as the acid dianhydride component. 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 the polyimide film which consists of a specific polyimide obtained by this.

  That is, in the diamine component of the polyimide constituting the chip-on-film of the present invention, if there is too much 3,4'-diaminodiphenyl ether, it becomes hard, and if it is too little, it is too soft, so 30-60 mol% is preferred, more preferably 35 It is -55 mol%, More preferably, it is 40-50 mol%. Moreover, since it will become soft when there are too many 4,4'- diamino diphenyl ethers, and it will become hard when there are too few, 40-70 mol% is preferable, More preferably, it is 45-65 mol%, More preferably, it is 50-60 mol%. .

  Among the polyimide films composed of such polyimide, those satisfying the following characteristics are more preferably used.

  That is, it is preferable that the elastic modulus, which is an index of hardness of the polyimide film, is in the range of 3 to 6 GPa. If it exceeds 6 GPa, it is too hard and if it is less than 3 GPa, it is too soft.

  In addition, the polyimide film of the present invention preferably has a linear expansion coefficient of 5 to 20 ppm / ° C. If the coefficient of thermal expansion exceeds 20 ppm / ° C, the dimensional change due to heat is too large. Since the difference from the linear expansion coefficient becomes large, warping occurs.

  Moreover, since the dimensional change by humidity is too large when the humidity expansion coefficient exceeds 25 ppm /% RH, the polyimide film of the present invention preferably has a humidity expansion coefficient of 25 ppm /% RH or less.

  Further, in the polyimide film of the present invention, when the water absorption exceeds 3%, the dimensional change of the film becomes large due to the influence of the sucked water, so that the water absorption is preferably 3% or less.

  In addition, in the polyimide film of the present invention, when the heat shrinkage rate at 200 ° C. for 1 hour exceeds 0.10%, the dimensional change due to heat is also increased, so that the heat shrinkage rate is 0.10% or less. preferable.

  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 3,3′-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 ' -Diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,6-diaminopyridine, bis- (4-aminophenyl) diethylsilane, 3,3'-dichlorobenzidine, Bis- (4-aminophenyl) ethyl Sufinoxide, 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′-dimethoxybenzidine, 2,4-bis (p-β -Amino-tert-butylphenyl) ether, bis (p-β-amino-tert-butylphenyl) ether, p-bis (2-methyl-4-aminopentyl) benzene, p-bis- (1,1-dimethyl) -5-aminopentyl) benzene, m-xylylenediamine, p-xylylenediamine, 1,3-diaminoadamantane, 3,3'-diamino-1,1'-diaminoadamer Nanthane, 3,3′-diaminomethyl 1,1′-diadamantane, bis (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, 3-methylhepta Methylenediamine, 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-oxadi Azole, 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 that is a precursor of the polyimide film include, for example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethylformamide, Formamide solvents such as N, N-diethylformamide, acetamide solvents such as N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidones such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone Examples include solvents, phenolic solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, and catechol, and aprotic polar solvents such as hexamethylphosphoramide and γ-butyrolactone. These alone Although it is desirable to use as a mixture, further xylene, the use of aromatic hydrocarbons such as toluene are also possible.

  Any of the following known methods (1) to (5) can be adopted as a method for polymerizing such polyimide.

  (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. .

  In the present invention, it is essential to add specific inorganic particles in order to improve running properties (slidability).

  That is, the inorganic particles have a powder particle diameter in the range of 0.01 to 1.5 μm and an average particle diameter in the range of 0.05 to 0.7 μm, more preferably 0.1 to 0. When it is in the range of .6 μm, even more preferably in the range of 0.3 to 0.5 μm, inspection of the polyimide film with an automatic optical inspection system can be applied without problems. Further, it can be used without causing deterioration of the mechanical properties of the film. Conversely, if the average particle size is below these ranges, sufficient slipperiness to the film tends not to be obtained, and if the average particle size is above these ranges, the automatic inspection system causes the particles to become foreign matter. It is not preferable because it is mistakenly detected and causes trouble.

  Such specific inorganic particles are required to be dispersed and contained in the range of 0.1 to 0.9% by weight per film resin weight, and preferably dispersed and contained in the range of 0.3 to 0.8% by weight. More preferably. When the content of the inorganic particles is 0.1% by weight or less, the number of protrusions on the film surface is insufficient, so that sufficient slipperiness to the film cannot be obtained, the transportability is deteriorated, and the film is wound on a roll. It is not preferable because the appearance of the film wound is deteriorated. If the content of inorganic particles exceeds 0.9% by weight, the slipperiness of the film will be improved, but coarse protrusions due to abnormal aggregation of particles will increase, resulting in false detection of foreign matter by the automatic inspection system. It is not preferable because it causes trouble.

  Further, in the polyimide film of the present invention, the particle size distribution of the inorganic particles is narrow and narrow, that is, particles having a particle size of 0.15 to 0.60 μm account for 80% by volume or more of all particles. It is essential. If the proportion of particles having a particle size of 0.15 μm or less falls below the range of the particle size distribution, the slipperiness of the film decreases, which is not preferable. In addition, it is possible to remove coarse particles with a 5 μm cut filter or a 10 μm cut filter when feeding inorganic particles, but if the proportion of particles of 0.60 μm or more increases, the filter will frequently clog. This is not preferable because the process stability is impaired and coarse aggregation of particles is likely to occur.

  In the polyimide film of the present invention, it is preferable that the number of protrusions having a size of 20 μm or more is 1/40 cm square or less in film surface protrusions caused by inorganic particles. The number of protrusions having a height of 2 μm or more is 5 pieces / 40 cm square or less, more preferably 3 pieces / 40 cm square or less, and still more preferably 1 piece / 40 cm square or less. If the amount is larger than this, the filler may straddle between the wirings, leading to failure of conduction, and it is easy to cause problems such as breaking through the film thickness of the photoresist mask. Is not preferable.

  The surface protrusions of the inorganic particles increase the film surface area, and the surface is sufficiently roughened so that the anchor effect is observed and the adhesiveness is not impaired.

A slurry in which such inorganic particles are dispersed in the same polar solvent as the organic solvent used in the production of polyimide is added to the polyamic acid solution in the polyimide production process, followed by decyclization and desolvation to obtain a polyimide film. Although it is preferable to obtain, after adding inorganic particle slurry in the organic solvent before polyamic acid polymerization, polyamic acid polymerization, decyclization and desolvation, etc., to obtain a polyimide film, etc. in the step before decyclization and desolvation It is possible to add the inorganic particle slurry in any process. Specific examples of the inorganic particles include SiO ₂ (silica), TiO ₂ , CaHPO ₄ , Ca ₂ P ₂ O _{7 and the} like. Among them, silica produced by a wet pulverization method such as a sol-gel method is preferable because it is stable in a varnish-like polyamic acid solution and physically stable, and does not affect various physical properties of the polyimide.

  Furthermore, the fine silica powder is agglomerated by using it as a silica slurry that is uniformly dispersed in a polar solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, and n-methylpyrrolidone. It is preferable to prevent this. Since this slurry has a very small particle size, the sedimentation rate is slow and stable. Even if it settles, it can be easily redispersed by re-stirring.

  Moreover, although it does not specifically limit about the thickness of the polyimide film of this invention, Preferably it is 1-225 micrometers, More preferably, it is 5-175 micrometers. If the thickness of the polyimide film is too thick, winding deviation tends to occur when it is made into a roll shape, and wrinkles and the like are likely to occur when it is too thin.

  Wiring is formed on one or both sides of the polyimide film as described above so that an IC chip can be mounted with or without an adhesive, thereby forming the chip-on-film of the present invention.

  As the adhesive used here, an adhesive made of at least one resin selected from an epoxy resin, an acrylic resin, and a polyimide resin is preferably used. Of these, epoxy resins and polyimide resins are particularly preferably used. 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 method for forming the wiring constituting the chip-on-film of the present invention include a subtractive method, a semi-additive method, and a full additive method.

  First, the semi-additive method is a method in which a metal layer to be a seed layer is 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 patterning into a wiring pattern by developing, forming a wiring by electroless plating or electrolytic plating on the seed layer using the patterned photoresist layer as a plating mask, and then removing the photoresist completely, and finally It means a method of removing the seed layer other than the wiring 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 thus configured chip-on film of the present invention has an appropriate elastic modulus as well as high dimensional stability, and further has slipperiness by adding inorganic fine particles to generate surface protrusions, and chip-on film. Because it uses a polyimide film that can be adapted to an automatic optical inspection system (AOI) for film (COF), it is extremely excellent in bendability and should be preferably applied to various IC chip mounting applications that require fine wiring. Can do.

  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, the polyimide film used by the comparative example uses what was formed by the synthesis examples 7-12. Further, as the adhesive used in the examples, those prepared in Synthesis Example 13 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 as follows using the Mitutoyo lightmatic (Series318) thickness meter. That is, 15 points were selected arbitrarily from the entire surface of the film, the thicknesses were measured at these 15 points, and the average was calculated to obtain the thickness.

(2) Linear expansion coefficient A TMA-50 thermomechanical analyzer manufactured by Shimadzu Corporation was used, and measurement was performed under conditions of a measurement temperature range of 50 to 200 ° C and a temperature increase rate of 10 ° C / min. The load was 0.25 N, and the temperature was first raised from 35 ° C. at 10 ° C./min to 300 ° C. Hold at 300 ° C. for 5 minutes, then lower the temperature at 10 ° C./minute to lower the temperature to 35 ° C., hold at 35 ° C. for 30 minutes, then raise the temperature at 10 ° C./minute to raise the temperature to 300 ° C. It was. The data at the time of the second temperature increase from 35 ° C. to 300 ° C. was read, and the linear expansion coefficient was calculated from the average of the portion of 50 to 200 ° C.

(3) Elasticity modulus RTM-250 Tensilon universal testing machine manufactured by A & D was used, and the tensile velocity was measured under the condition of 100 mm / min. Load cell 10Kgf, measurement accuracy ± 0.5% full scale, measure stress-strain curve, slope of straight line of rising part of stress-strain curve (calculated by least square method between 2N to 15N), initial Calculation was performed as follows from the sample length, the sample width, and the sample thickness.
Elastic modulus = (Slope of straight line portion × initial sample length) / (sample width × sample thickness)

(4) Humidity expansion coefficient At 25 ° C, a film was mounted in a TM7000 furnace manufactured by ULVAC, dried air was fed into the furnace and dried for 2 hours, and then the TM7000 furnace was supplied with air from an HC-1 type steam generator. Was humidified to 90% RH, and the coefficient of humidity expansion was determined from the dimensional change during that period. The humidification time was 7 hours. The data from 3RH% to 90RH% was read, and the humidity expansion coefficient was calculated from the average of the portion of 3 to 90RH%.

(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. Specifically, the film was cut into a 6 cm diameter circle, and the weight (W0) after heat treatment at 200 ° C. for 1 hour was measured as the dry weight, and then allowed to stand in a desiccator under a 98% RH atmosphere for 2 days. The weight (W1) of the water-absorbed film was measured, and the water absorption rate was determined by the following formula.
Water absorption rate = (W1-W0) / WO × 100

(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

(7) Friction coefficient (Static friction coefficient)
The films were overlapped and measured based on JIS K-7125 (1999). That is, using a slip coefficient measuring device Slip Tester (manufactured by Technonez Co., Ltd.), overlapping the films, placing a 200 g weight thereon, fixing one of the films, pulling the other at 100 mm / min, The coefficient of friction was measured.

(8) Automatic optical inspection (AOI)
The base film was inspected using SK-75 manufactured by Orbotech. The case where a foreign substance and a fine particle could be distinguished was evaluated as “◯”, while the case where the size of the foreign substance and the fine particle was similar and could not be distinguished from each other was evaluated as a “x” evaluation.

(9) Evaluation of inorganic particles Using a laser diffraction / scattering particle size distribution measuring apparatus LA-910 manufactured by HORIBA, Ltd., a sample dispersed in a polar solvent was measured and analyzed, and the particle size range, average particle size, and particle size were obtained. The occupancy ratio for all particles of 0.15 to 0.60 μm was read.

(10) Number of abnormal protrusions The number of protrusions having a size of 20 μm or more and the number of protrusions having a height of 2 μm or more were counted per 40 cm square area of the film. The size measurement and the height measurement were performed by using a scanning laser microscope “1LM15W” manufactured by Lasertec Co., Ltd., using a Nikon 100 × lens (CF Plan 100 × / 0.95∞ / 0 EPI). It was confirmed by photographing and analyzing the film surface in the “mode”.

(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 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. In this mixture, particles having a particle size of 0.01 μm or more and 1.5 μm or less, an average particle size of 0.40 μm, and a particle size of 0.15 to 0.60 μm are 88.0% by volume in all particles. The N, N-dimethylacetamide slurry of silica was added to the varnish-like polyamic acid solution at 0.35% by weight per resin weight, sufficiently stirred and dispersed, and then rotated at 100 ° C. from a T-type slit die. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.20 mm was obtained by casting on the top. 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 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. In this mixture, particles having a particle size of 0.01 μm or more and 1.5 μm or less, an average particle size of 0.38 μm, and a particle size of 0.15 to 0.60 μm were 86.3% by volume in all particles. The N, N-dimethylacetamide slurry of silica was added to the varnish-like polyamic acid solution at 0.35% by weight per resin weight, sufficiently stirred and dispersed, and then rotated at 100 ° C. from a T-type slit die. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.30 mm was obtained by casting on the top. 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 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. In this mixture, particles having a particle size of 0.01 μm or more and 1.5 μm or less, an average particle size of 0.37 μm, and a particle size of 0.15 to 0.60 μm were 87.1% by volume in all particles. A N, N-dimethylacetamide slurry of silica was added to the varnish-like polyamic acid solution at 0.50% by weight per resin weight, sufficiently stirred and dispersed, and then rotated at 100 ° C. from a T-type slit die. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.20 mm was obtained by casting on the top. 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 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. In this mixture, the particle diameter is 0.01 μm or more and 1.5 μm or less, and the average particle diameter is 0.44 μm and the particle diameter is 0.15 to 0.60 μm. A stainless steel drum of 100 ° C. rotated by a T-type slit die after adding 0.42% by weight of the silica N, N-dimethylacetamide slurry to the varnish-like polyamic acid solution, thoroughly stirring and dispersing the slurry. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.30 mm was obtained by casting on the top. 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 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 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 composed 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. In this mixture, particles having a particle size of 0.01 μm or more and 1.5 μm or less, an average particle size of 0.33 μm, and a particle size of 0.15 to 0.60 μm were 86.9% by volume in all particles. The silica N, N-dimethylacetamide slurry was added to the varnish-like polyamic acid solution at 0.40% by weight per resin weight, sufficiently stirred and dispersed, and then rotated at 100 ° C. from a T-type slit die. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.30 mm was obtained by casting on the top. 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 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. In this mixture, the particle size is 0.01 μm or more and 1.5 μm or less, the average particle size is 0.43 μm, and the particle size is 0.15 to 0.60 μm. After adding 0.45% by weight of the silica N, N-dimethylacetamide slurry to the varnish-like polyamic acid solution, sufficiently stirring and dispersing, the resulting mixture is rotated by a T-type slit die. The gel film was cast on a stainless steel drum at 100 ° C. to obtain a self-supporting gel film having a residual volatile component of 55% by weight 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 7)
Pyromellitic dianhydride (molecular weight 218.12) / 4,4′-diaminodiphenyl ether (molecular weight 200.24) is mixed at a molar ratio of 50/50, and DMAc (N, N-dimethylacetamide) 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. In this mixture, particles having a particle size of 0.01 μm or more and 1.5 μm or less, an average particle size of 0.38 μm, and a particle size of 0.15 to 0.60 μm were 86.3% by volume in all particles. The N, N-dimethylacetamide slurry of silica was added to the varnish-like polyamic acid solution at 0.35% by weight per resin weight, sufficiently stirred and dispersed, and then rotated at 100 ° C. from a T-type slit die. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.30 mm was obtained by casting on the top. 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 2.

(Synthesis Example 8)
In Synthesis Example 2, a polyimide film was obtained in the same manner as in Synthesis Example 2 except that silica was not added. The physical properties are shown in Table 2.

(Synthesis Example 9)
The silica used in Synthesis Example 2 has a particle diameter of 0.1 μm or more and 4.5 μm or less, particles having an average particle diameter of 1.1 μm and a particle diameter of 0.15 to 0.60 μm in all particles. The same method as in Synthesis Example 2 except that 27.3 volume% calcium hydrogen phosphate was changed and 0.2% by weight of N, N-dimethylacetamide slurry was added to the varnish-like polyamic acid solution per resin weight. A polyimide film was obtained. The physical properties are shown in Table 2.

(Synthesis Example 10)
The silica used in Synthesis Example 2 has a particle diameter of 0.01 μm or more and 0.3 μm or less, particles having an average particle diameter of 0.08 μm and a particle diameter of 0.15 to 0.60 μm in all particles. A polyimide film was prepared in the same manner as in Synthesis Example 2 except that the silica was changed to 31.4% by volume and N, N-dimethylacetamide slurry was added to the varnish-like polyamic acid solution at 0.35% by weight per resin weight. Got. The physical properties are shown in Table 2.

(Synthesis Example 11)
The silica used in Synthesis Example 2 has a particle size of 0.01 μm or more and 1.5 μm or less, particles having an average particle size of 0.4 μm and a particle size of 0.15 to 0.60 μm in all particles. A polyimide film was prepared in the same manner as in Synthesis Example 2 except that 72.6% by volume of silica was changed and 0.35% by weight of N, N-dimethylacetamide slurry was added to the varnish-like polyamic acid solution per resin weight. Got. The physical properties are shown in Table 2.

(Synthesis Example 12)
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (molecular weight 294.22) / paraphenylenediamine (molecular weight 108.14) were mixed at a molar ratio of 50/50, and DMAc (N, N-dimethylacetamide) was polymerized into a 18.5 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. In this mixture, particles having a particle size of 0.01 μm or more and 1.5 μm or less, an average particle size of 0.38 μm, and a particle size of 0.15 to 0.60 μm were 86.3% by volume in all particles. The N, N-dimethylacetamide slurry of silica was added to the varnish-like polyamic acid solution at 0.35% by weight per resin weight, sufficiently stirred and dispersed, and then rotated at 100 ° C. from a T-type slit die. The gel film having a self-supporting property having a residual volatile component content of 55% by weight and a thickness of about 0.30 mm was obtained by casting on the top. 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 2.

(Synthesis Example 13)
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 and the vacuum chamber was brought to an ultimate pressure of 1 × 10 ⁻³ Pa, and then nickel / chromium = 95/5 by DC magnetron sputtering at an argon gas pressure of 1 × 10 ⁻¹ Pa. (Weight ratio) nichrome alloy was sputtered on one side so as to have a thickness of 5 nm, and copper was further sputtered so as to have 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 manufactured 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 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 3.

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 3.

  Moreover, the static friction coefficient of the polyimide film part of the obtained single-sided wiring board, AOI, and the number of abnormal protrusions were measured. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

(Example 2)
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 2 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

Example 3
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 3 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

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, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

(Example 5)
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 5 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

(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, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

(Example 7)
Using the polyimide film formed in Synthesis Example 2, the adhesive of Synthesis Example 13 was applied to one surface 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 3.

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 3.

  Moreover, the static friction coefficient of the polyimide film part of the obtained single-sided wiring board, AOI, and the number of abnormal protrusions were measured. The results are shown in Table 3. Low static friction coefficient, good transportability, no abnormal protrusion, no false detection in AOI inspection, and inspection can proceed smoothly, and there is no protrusion across circuit line / space, and it can be applied as a chip-on film Met.

(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, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Since the polyimide film portion of the obtained single-sided wiring board has a high coefficient of thermal expansion, the dimensional change rate after 300 ° C. solder bath treatment is large, and the dimensional accuracy of the circuit is significantly deteriorated. Met.

(Comparative Example 2)
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 8 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Since the polyimide film portion of the obtained single-sided wiring board has a high coefficient of static friction and poor slipperiness, it causes problems when transporting the chip-on film, and thus cannot be applied for chip-on-film use.

(Comparative Example 3)
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 9 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. In the polyimide film part of the obtained single-sided wiring board, abnormal projections are erroneously detected as foreign matters in the AOI inspection, so that the foreign matter inspection cannot be sufficiently performed, and the generated abnormal projections are between the circuit lines / spaces. It straddles and cannot be applied as a chip-on-film.

(Comparative 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 10 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Since the polyimide film portion of the obtained single-sided wiring board has a high coefficient of static friction and poor slipperiness, it causes problems when transporting the chip-on film, and thus cannot be applied for chip-on-film use.

(Comparative Example 5)
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 11 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. In this example, since the occupation ratio of the particle diameter of 0.9 to 1.3 μm occupied 22.0% by volume of the whole, the number of abnormal protrusions increased due to this. In the polyimide film part of the obtained single-sided wiring board, abnormal projections are erroneously detected as foreign matters in the AOI inspection, so that the foreign matter inspection cannot be sufficiently performed, and the generated abnormal projections are between the circuit lines / spaces. It straddles and cannot be applied as a chip-on-film.

(Comparative 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 12 was used, and the same evaluation as in Example 1 was performed. The results are shown in Table 3. Since the film elastic modulus is high, the tip of the inner lead is bent at 40% of the entire lead, which is not applicable for chip-on-film use.

  The chip-on film of the present invention has an appropriate elastic modulus as well as high dimensional stability, and is further excellent in excellent slipperiness and bendability, and can be applied to an automatic optical inspection system (AOI). The present invention can be preferably applied to various IC chip mounting applications that require fine wiring.

(A) is a top view of the IC chip mounting part which shows an example of the structure 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 (9)

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. Diphenyl ether is mainly composed of pyromellitic dianhydride as an acid dianhydride component, and the polyimide film has a particle size of 0.01 to 1.5 μm and an average particle size of 0.00. Inorganic particles having a particle size distribution in which particles having a particle size of 0.15 to 0.60 μm account for 80% by volume or more of all particles are 0.1 to 0.5 μm per film resin weight. It is dispersed and contained at a ratio of 0.9% by weight, and the wiring is via an adhesive or via an adhesive Ku, chip-on-film characterized by being formed on at least one surface of the polyimide 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 6 GPa, a linear expansion coefficient at 50 to 200 ° C. of 5 to 20 ppm / ° C., a humidity expansion coefficient of 30 ppm /% RH or less, and a water absorption of 3.5% or less. The chip-on film according to claim 1, wherein a heat shrinkage rate at 200 ° C. for 1 hour is 0.10% or less. The chip-on film according to claim 1, wherein the number of protrusions having a size of 20 μm or more present on the surface of the polyimide film is 1/40 cm square or less. 5. The chip-on film according to claim 1, wherein the number of protrusions having a height of 2 μm or more present on the surface of the polyimide film is 5/40 cm square 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 is made of at least one selected from an epoxy resin, an acrylic resin, and a polyimide resin.

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