JP2018168358A - Polyimide film - Google Patents

Abstract

A novel polyimide film that can be used for a double-sided copper-clad laminate or the like is provided. In a first aspect, in a polyimide film containing inorganic particles, the ratio of protrusions having a height of 0.8 μm or more on one surface a of the film is A / 100 cm 2, and the height on the other surface b of the film is high. When the ratio of the protrusions having a thickness of 0.8 μm or more is B / 100 cm 2, both A and B are 10 or less. In the second aspect, in the polyimide film containing inorganic particles, the absolute value of the difference between A and B may be 2 or more. [Selection diagram] None

Description

  The present invention relates to a polyimide film.

Printed wiring boards for mounting electronic components such as ICs and LSIs are becoming more and more demanding in a small space as electronic devices become smaller, lighter, and more functional. A COF (Chip On Film) method has been developed and put into practical use.
In recent years, the trend has been particularly noticeable in the mounting of ICs that drive displays such as LCD TVs, laptop computers, and smartphones. With the increase in display definition, mobile devices becoming thinner, and higher functionality, higher density mounting has been achieved. Improvement of mounting methods such as miniaturization wiring for realizing and double-sided COF with wiring on both sides is progressing.

  As the copper-clad laminate used for COF, a two-layer type in which a copper layer is directly formed on a polyimide film and does not use an adhesive, which can cope with the miniaturization of wiring, is employed. There are a method of forming a copper layer on a film by sputtering and plating, and a method of imidizing after casting a polyamic acid on a copper foil. However, the copper layer can be easily made thin and advantageous for fine wiring. Two-layer copper-clad laminates by sputtering / plating are the mainstream.

  The fine wiring of the COF substrate is formed by providing a photoresist layer on the surface of the copper layer of the copper-clad laminate, exposing and developing the photoresist layer to form a desired pattern, and using this pattern as a masking material. A method of selectively etching the copper layer (subtractive method) is used. However, with this method, it is difficult to reduce the wiring pitch [for example, smaller than 25 μm (for example, smaller than line width 12 μm, space width 13 μm)], and it is difficult to cope with some of the most advanced models.

  In recent years, as an alternative method, a base metal layer is formed on the surface of an insulating substrate, a photoresist layer is provided on the surface of the base metal layer, a desired pattern is formed on the photoresist layer, and an exposed substrate is formed. Attention has been focused on a method (semi-additive method) in which a conductive metal is electrolytically deposited on a metal layer to form a wiring pattern. According to this method, a small wiring pitch (for example, 20 μm or less) can be formed, and further high-density mounting is possible.

In these technical trends, the characteristics and quality requirements for polyimide films used for two-layer copper-clad laminates are becoming increasingly sophisticated. For example, a COF is mounted on an electronic device after being mounted with an IC or panel, and is mounted on an electronic device. However, since the wiring is likely to be cracked, crack resistance is also required. It became so.
In order to cope with these, for example, a base metal layer made of a nickel alloy is formed on the surface of the polyimide film without using an adhesive, and a wiring having a laminated structure including a copper layer on the surface of the base metal layer is formed by a semi-additive method. In the manufacturing method of a flexible wiring board, the proposal which prescribed | regulated the crystal orientation of a copper layer is made | formed (patent document 1).

JP 2014-159608 A

  An object of the present invention is to provide a novel polyimide film.

As described above, various studies have been made on COF, but the present inventors have found that there is room for further study and improvement.
For example, in a double-sided COF with wiring on both sides, the folding angle of the inner wiring is smaller than that of the outer wiring, and the problem of wiring cracking is likely to occur in conjunction with the miniaturization of the wiring. In order to cope with this, it is not sufficient to improve the copper layer as in Patent Document 1, and it is considered that the polyimide film needs to be improved.

  In addition, as fine wiring progresses, the quality of the copper layer surface and the quality of the polyimide film surface become higher, and finer foreign matters and defects than before will affect the wiring formation yield. Furthermore, copper-clad laminates used for semi-additive wiring formation are laminated with a copper layer thickness of 1/3 or less (1-3 μm) compared to copper-clad laminates used in conventional subtractive methods. Since a plate is often used, higher quality is required on the surface of the polyimide film.

  The present inventor tried various studies from such a viewpoint, but it was extremely difficult to satisfy sufficient performance. For example, while trying to smooth the polyimide film surface, etc., simply doing such an attempt will not only reduce the slipperiness between films, but also reduce the handleability, as well as during film transport and winding. Occasionally, scratches and wrinkles are likely to occur, and the film surface quality may be deteriorated.

  In such circumstances, the present inventors, as a result of earnest research, in the polyimide film containing inorganic particles, paying attention to both sides of the film, adjusting the protrusion ratio etc. on both sides, polyimide film excellent in handleability and The inventors have found that a polyimide film suitable for double-sided COF and the like can be obtained, and have further studied and completed the present invention.

That is, the present invention relates to the following inventions and the like.
[1]
A polyimide film containing inorganic particles, the ratio of protrusions having a height of 0.8 μm or more on one surface a of the film being A / 100 cm ² , and protrusions having a height of 0.8 μm or more on the other surface b of the film When the ratio is B / 100 cm ² , a polyimide film in which A and B are both 10 or less (for example, a polyimide film for double-sided COF).
[2]
A polyimide film containing inorganic particles, the ratio of protrusions having a height of 0.8 μm or more on one surface a of the film being A / 100 cm ² , and protrusions having a height of 0.8 μm or more on the other surface b of the film When the ratio is B / 100 cm ² , a polyimide film (for example, a polyimide film for double-sided COF) in which the absolute value of the difference between A and B is 2 or more.
[3]
The polyimide film according to [1] or [2], wherein A and / or B is 2 or more.
[4]
The polyimide according to any one of [1] to [3], wherein the surface roughness Ra is 0.01 to 0.05 μm and the surface roughness Rz is 0.05 to 0.6 μm on both surfaces a and b. the film.
[5]
The polyimide film according to any one of [1] to [4], wherein a thermal expansion coefficient in the MD direction is 4 to 10 ppm / ° C, and a thermal expansion coefficient in the TD direction is 0 to 8 ppm / ° C.
[6]
The polyimide film according to any one of [1] to [5], which satisfies a tensile elastic modulus of 5 to 10 GPa and / or a loop stiffness of 10 to 75 mN / cm.
[7]
The polyimide film in any one of [1]-[6] comprised with the polyimide which uses the aromatic diamine component containing paraphenylenediamine, and an acid anhydride component as a polymerization component.
[8]
The polyimide film according to any one of [1] to [7], wherein the average particle diameter of the inorganic particles is 0.05 to 0.5 μm.
[9]
[1] to [8] A metal laminate using the polyimide film according to any one of [8] (particularly a double-sided copper-clad laminate).
[10]
[9] The metal laminated board (especially double-sided copper clad laminated board) whose copper thickness is 1-3 micrometers.
[11]
[9] A substrate for double-sided COF using the metal laminated plate (especially double-sided copper-clad laminate) according to [10].
[12]
A method for producing a double-sided COF substrate by a semi-additive method using the metal laminated plate (especially a double-sided copper-clad laminate) according to [9] or [10].

  In the present invention, a novel polyimide film can be obtained. In particular, the present invention can also provide a polyimide film having an excellent balance of dimensional stability, folding characteristics, surface smoothness on both sides of the film, and the like.

  Such a polyimide film is suitable, for example, for COF (Chip On Film). In particular, it can be suitably used for fine pitch circuit boards and semiconductor packages such as double-sided COF with wiring on both sides for the purpose of high-density mounting.

It is sectional drawing of the copper clad laminated body which used the polyimide film as a base material. It is sectional drawing and surface drawing of the board | substrate for dimension evaluation COF which formed the copper wiring circuit pattern in the polyimide film. It is a figure which shows the cycle which bends the board | substrate for dimension evaluation COF, and makes it the original state. It is sectional drawing after pressure-bonding glass to the board | substrate for dimension evaluation COF.

[Polyimide film]
In the polyimide film of the present invention, the ratio of specific protrusions is adjusted on both surfaces of the film.

First, in the first aspect, in the polyimide film, the ratio of protrusions having a height of 0.8 μm or more on one side a of the film is A / 100 cm ² (A per 100 cm ² ), and the other side b of the film is When the ratio of protrusions having a height of 0.8 μm or more is B / 100 cm ² (B per 100 cm ² ), A and B are each 20 or less (for example, 18 or less), preferably 15 or less. (For example, 12 or less), more preferably 10 or less (for example, 9 or less, 8 or less).

  The lower limit values of the protrusion ratios A and B are not particularly limited, but may be, for example, 0 or a finite value (1, 2, etc.), respectively.

  Thus, it is easy to efficiently suppress defects such as pinholes by suppressing the ratio of specific protrusions on both sides of the film. Therefore, such a film is easy to improve the yield and is suitable as a film for providing a metal layer such as copper on both sides. According to the study by the present inventor, surprisingly, among the protrusions, there seems to be a high correlation between the protrusions of 0.8 μm or more and defects such as pinholes.

In the second aspect of the present invention, in the polyimide film, the absolute value of the difference between A and B is 1 or more, preferably 2 or more (for example, 3 or more).
The upper limit of the absolute value of the difference between A and B is not particularly limited. For example, 30, 25, 20, 18, 16, 14, 12, 10, 9, 8, 7, 6, etc. Also good.

  Thus, it is easy to ensure sufficient slipperiness between the surface a and the surface b of the film by giving a bias to the ratio of specific protrusions on both surfaces of the film, or it is wound up in a roll shape during film production. In some cases, it is easy to efficiently obtain a film having excellent handleability. Also, in relation to such excellent handling properties, scratches and wrinkles are not easily generated on the film, and it is easy to efficiently form wiring on the film (easy to form wiring with high yield).

  The polyimide film of this invention should just satisfy at least 1 aspect of a 1st aspect and a 2nd aspect, More preferably, you may satisfy both aspects.

  In the first aspect and / or the second aspect, at least one of A and B (A and / or B) is a finite value [for example, one or more, preferably two or more (for example, 2 to 10). , 2-8, 3-7, etc.)]. Darely forming protrusions on at least one of the surfaces makes it easy to obtain a film having a good balance of good wiring formation and handleability.

  The polyimide film of the present invention may have a predetermined surface roughness. For example, the Ra (center line average roughness) of the polyimide film may be, for example, about 0.01 to 0.05 μm and about 0.01 to 0.04 μm. The Rz (10-point average roughness) of the polyimide film may be 0.05 to 0.6 μm, preferably 0.1 to 0.5 μm.

  In addition, such surface roughness may be satisfied in any one of the surface a and the surface b of a film, and may be satisfied in the surface a and the surface b.

  According to the polyimide film having such a surface roughness (particularly, a polyimide film satisfying a combination of such a surface roughness and the first and / or the second aspect) Hole) is less likely to occur and the yield is easily improved. In addition, when processing films or creating copper-clad laminates, it is easy to ensure sufficient film slipperiness, which may result in poor transport or scratches that reduce the yield on the film surface. It seems to be easy to hold down and it is easy to obtain a good film.

  The polyimide film of the present invention may have a specific thermal expansion coefficient. For example, the thermal expansion coefficient of the polyimide film is 4 to 10 ppm / ° C., preferably 3.5 to 9 ppm / ° C., more preferably about 3 to 8 ppm / ° C. in the MD direction (machine transport direction, longitudinal direction, flow direction). It may be 0 to 8 ppm / ° C., preferably 0 to 6 ppm / ° C., more preferably about 0.5 to 5 ppm / ° C. in the TD direction (width direction, lateral direction, right angle direction). .

  By setting the thermal expansion coefficient in such a range, it becomes difficult for bonding failure to occur at the time of mounting with a semiconductor or a glass panel, and it is easy to obtain a film more suitable for fine pitch circuit boards and semiconductor package applications.

  The tensile modulus of the polyimide film of the present invention is preferably 5 GPa or more (for example, 5 to 10 GPa), more preferably MD is 6 to 8 GPa, and TD is 7 to 10 GPa. Such tensile elastic modulus may be satisfied in the MD direction and / or TD direction of the film, and may be satisfied particularly in both the MD direction and the TD direction.

  The loop stiffness of the polyimide film of the present invention is preferably 10 to 75 mN / cm, and more preferably 10 to 65 mN / cm.

  The polyimide film of the present invention usually contains inorganic particles (or fillers). Such inorganic particles are not particularly limited, and examples thereof include titanium oxide, silica, calcium carbonate, calcium phosphate, and calcium hydrogen phosphate.

The average particle diameter of the inorganic particles is, for example, 0.01 to 5 μm, preferably 0.02 to 2 μm (for example, 0.03 to 1 μm), and more preferably about 0.05 to 0.5 μm.
The average particle size of the inorganic particles was measured with a laser diffraction / confusion type particle size distribution measuring apparatus LA-920 manufactured by Horiba, Ltd. in a slurry state dispersed in DMAc (N, N-dimethylacetamide), for example. In the particle size distribution, the median diameter is defined as the average particle diameter.

  The content of the inorganic particles is not particularly limited as long as the effect of the present invention is not hindered. For example, the content of the inorganic particles is 0.05% by mass or more, preferably 0.1 to 1.5% by mass, more preferably, with respect to the polyimide film. 0.3-1.0 mass% may be sufficient.

(Manufacturing method of polyimide and polyimide film)
The polyimide film (or polyimide constituting the polyimide film or polyamic acid) usually has an aromatic diamine component and an acid anhydride component (tetracarboxylic acid component) as polymerization components. The polymerization component may contain other polymerization components as long as the main component is an aromatic diamine component and an acid anhydride component.
Although it does not specifically limit when manufacturing a polyimide film, First, a polyamic acid (polyamic acid) solution is obtained by polymerizing an aromatic diamine component and an acid anhydride component in an organic solvent.

In particular, the polyimide film of the present invention may suitably contain paraphenylenediamine as the aromatic diamine component. Thus, by using the aromatic diamine component containing paraphenylene diamine, it is easy to efficiently obtain a polyimide film having the above characteristics and properties.
The aromatic diamine component may contain things other than paraphenylenediamine. Specific examples of the aromatic diamine component other than such paraphenylenediamine include metaphenylenediamine, benzidine, paraxylylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4 ′. -Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3'-dimethoxybenzidine, 1,4-bis (3 -Methyl-5-aminophenyl) benzene and their amide-forming derivatives. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.
As the aromatic diamine component, a combination of paraphenylenediamine and 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether is preferable. In this, adjusting the amount of diamine component of paraphenylenediamine and 3,4'-diaminodiphenyl ether, which have the effect of increasing the tensile modulus of the film, and setting the tensile modulus of the resulting polyimide film to 5 GPa or more, It is preferable because the transportability is improved.

  Specific examples of the acid anhydride component include pyromellitic acid, 3,3 ′, 4,4′-diphenyltetracarboxylic acid, 2,3 ′, 3,4′-diphenyltetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5,6-tetra Aromatic tetracarboxylic anhydride components such as carboxylic acid and amide-forming derivatives thereof can be mentioned, and pyromellitic dianhydride and 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride are preferable. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  Among these, a particularly preferred combination of the aromatic diamine component and the acid anhydride component is one or more selected from the group consisting of paraphenylenediamine, 4,4′-diaminodiphenyl ether and 3,4′-diaminodiphenyl ether. Examples include a combination of an aromatic diamine component and one or more acid anhydride components selected from the group consisting of pyromellitic dianhydride and 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride. .

The blending ratio of paraphenylenediamine in the aromatic diamine component described above is based on the total amount of the aromatic diamine component from the viewpoint of obtaining a coefficient of thermal expansion within the above range, giving appropriate strength to the film, and preventing poor running properties. And may be selected from the range of 15 mol% or more (for example, 18 mol% or more), usually 20 mol% or more (for example, 25 mol% or more), preferably 30 mol% or more (for example, 31 mol% or more) , 32 mol% or more), preferably 33 mol% or more, and more preferably 35 mol% or more.
The upper limit of the proportion of paraphenylenediamine in the aromatic diamine component may be, for example, 100 mol%, and particularly less than 100 mol% [eg, 99 mol%, 95 mol%, 90 mol%, 80 mol%, 70 mol%, 60 mol% or less (for example, 60 mol%, 55 mol%, 52 mol%, 50 mol%, 48 mol%, 45 mol%, etc.).
Typically, the proportion of the paraphenylenediamine component in the aromatic diamine component is 15 to 80 mol% (for example, 18 to 75 mol%), 20 to 75 mol% (for example, 25-70 mol%), 30-65 mol% (for example, 32-60 mol%, 30-55 mol% (for example, 32-50 mol%)), etc. may be sufficient.
In addition, when the aromatic diamine component contains 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether (particularly 4,4′-diaminodiphenyl ether), 4,4′-diamino in the aromatic diamine component The proportion of diphenyl ether and / or 3,4'-diaminodiphenyl ether may be selected from the range of, for example, 85 mol% or less (for example, 82 mol% or less), preferably 80, based on the total amount of the aromatic diamine component. Mol% or less (for example, 78 mol% or less), more preferably 75 mol% or less (for example, 73 mol% or less), 70 mol% or less (for example, 68 mol% or less, 65 mol% or less), Also good.
The lower limit value of the ratio of 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether (particularly 4,4′-diaminodiphenyl ether) in the aromatic diamine component is not particularly limited, and for example, 1 mol%, It may be 5 mol%, 10 mol%, 15 mol%, 20 mol%, 30 mol%, 40 mol%, 45 mol%, 50 mol%, 52 mol%, 55 mol%, 60 mol%, and the like.
Typically, the proportion of 4,4′-diaminodiphenyl ether and / or 3,4′-diaminodiphenyl ether (particularly 4,4′-diaminodiphenyl ether) in the aromatic diamine component is based on the total amount of aromatic diamine component, 20-85 mol% (eg, 22-82 mol%), 25-80 mol% (eg, 30-78 mol%), 35-75 mol% (eg, 38-72 mol%), 40-70 mol% (For example, 45-70 mol%), 50-68 mol%, etc. may be sufficient.
The blending ratio (molar ratio) in the acid anhydride component is not particularly limited as long as the effects of the present invention are not hindered. For example, 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride is included. In this case, the content of 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride is preferably 15 mol% or more (for example, 18 mol% or more), preferably 20 mol based on the total amount of the acid anhydride component. % Or more is more preferable, and 25 mol% or more is more preferable.
The upper limit value of the ratio of 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride in the acid anhydride component may be 100 mol%, particularly less than 100 mol% (for example, 99 mol%, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 70 mol%, 60 mol%, 50 mol%, 45 mol%, 42 mol%, 40 mol%, 38 mol%, 35 mol%, 33 mol %).
Typically, the ratio of 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride in the acid anhydride component is 15 to 85 mol% (for example, 18 to 70 mol%), 18-60 mol% (for example, 18-50 mol%), 20-40 mol% may be sufficient.
When the acid anhydride component contains pyromellitic dianhydride, the proportion of pyromellitic dianhydride is, for example, 15 mol% or more (for example, 20 mol% or more), preferably, based on the entire acid anhydride component. May be about 25 mol% or more (for example, 30 mol% or more), more preferably about 35 mol% or more (for example, 40 mol% or more), % Or more, 55 mol% or more, 58 mol% or more, 60 mol% or more, 62 mol% or more, etc.).
The upper limit value of the proportion of pyromellitic dianhydride in the acid anhydride component is not particularly limited, and may be, for example, 100 mol%, particularly less than 100 mol% (for example, 95 mol%, 90 mol%, 85 mol%, 80 mol%, 82 mol%, 75 mol%, 72 mol%, etc.).
Typically, the proportion of pyromellitic dianhydride in the acid anhydride component is 10 to 95 mol% (for example, 12 to 90 mol%), 15 to 85 mol% ( For example, 20-82 mol%), 30-85 mol% (for example, 40-82 mol%), 50-80 mol% (for example, 60-80 mol%), etc. may be sufficient.
By using a polyamic acid composed of such an aromatic diamine component and an acid anhydride component as a raw material (precursor) of the polyimide film, the thermal expansion coefficient of the polyimide film is determined by the machine transport direction (MD) of the film, This is preferable because the width direction (TD) can be easily adjusted to the above range.

  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, and aprotic polar solvents such as hexamethylphosphoramide and γ-butyrolactone. These may be used alone or in combination of two or more. It is desirable to use as a mixture using And further can be xylene, the use of aromatic hydrocarbons such as toluene.

The polymerization method may be carried out by any known method. For example, (1) First, the total amount of the aromatic diamine component is put in a solvent, and then the acid anhydride component is equivalent to the total amount of the aromatic diamine component (equal mole) In addition to the polymerization method.
(2) A method in which the entire amount of the acid anhydride component is first put in a solvent, and then the aromatic diamine component is added so as to be equivalent to the acid anhydride component for polymerization.
(3) After putting one aromatic diamine component (a1) in a solvent, mixing for the time required for the reaction at a ratio of 95 to 105 mol% of one acid anhydride component (b1) with respect to the reaction component After that, the other aromatic diamine component (a2) is added, and then the other acid anhydride component (b2) is added so that the total aromatic diamine component and the total acid anhydride component are approximately equivalent. A method of adding and polymerizing.
(4) After putting one acid anhydride component (b1) in a solvent, mixing for a time required for the reaction at a ratio of 95 to 105 mol% of one aromatic diamine component (a1) with respect to the reaction component After that, the other acid anhydride component (b2) is added, and then the other aromatic diamine component (a2) is added so that the total aromatic diamine component and the total acid anhydride component are approximately equivalent. And then polymerize.
(5) A polyamic acid solution (A) is prepared by reacting one aromatic diamine component and an acid anhydride component in a solvent so that either one becomes excessive, and the other aromatic diamine component in another solvent. The polyamic acid solution (B) is prepared by reacting either of the acid anhydride component and the acid anhydride component in excess. A method in which the polyamic acid solutions (A) and (B) thus obtained are mixed 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) has excessive acid anhydride component, and the polyamic acid solution (A) has excessive acid anhydride component. In the case of the polyamic acid solution (B), the aromatic diamine component is excessive, the polyamic acid solutions (A) and (B) are mixed, and the total aromatic diamine component and total acid anhydride component used in these reactions are mixed. Adjust so that it is approximately equivalent. The polymerization method is not limited to these, and other known methods may be used.

  The polyamic acid solution thus obtained usually contains 5 to 40% by weight of solid content, and preferably contains 10 to 30% by weight of solid content. The viscosity is usually 10 to 2000 Pa · s as measured with a Brookfield viscometer, and preferably 100 to 1000 Pa · s for stable liquid feeding. Moreover, the polyamic acid in the organic solvent solution may be partially imidized.

  Next, the manufacturing method of a polyimide film 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 decyclizing it and heating it to remove the solvent is mentioned, but the latter can keep the coefficient of thermal expansion of the resulting polyimide film low. preferable.

  In the method of chemically decyclizing, first, the polyamic acid solution is prepared. In the present invention, usually, the polyamic acid solution may contain inorganic particles as described above.

  The polyamic acid solution used here may be a polyamic acid solution polymerized in advance, or may be polymerized sequentially when inorganic particles are contained.

  The polyamic acid solution may contain a cyclization catalyst (imidization catalyst), a dehydrating agent, a gelation retarder, and the like.

  Cyclization catalysts include amines such as aliphatic tertiary amines (trimethylamine, triethylenediamine, etc.), aromatic tertiary amines (dimethylaniline, etc.), heterocyclic tertiary amines (eg, isoquinoline, pyridine, β-picoline and the like). These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

Examples of the dehydrating agent include acid anhydrides such as aliphatic carboxylic acid anhydrides (eg, acetic anhydride, propionic anhydride, butyric anhydride), aromatic carboxylic acid anhydrides (eg, benzoic anhydride, etc.), and the like. . These may be used individually by 1 type, and 2 or more types may be mixed and used for them.
It does not specifically limit as a gel retarder, Acetyl acetone etc. can be used.

  As a method for producing a polyimide film from a polyamic acid solution, a polyamic acid solution (particularly, a polyamic acid solution containing a cyclization catalyst and a dehydrating agent) is cast on a support and molded into a film shape. Examples include a method in which imidization is partially advanced on the body to form a gel film having self-supporting property, and then peeled from the support, heat-dried / imidized, and subjected to heat treatment.

  Examples of the support include a metal rotating drum and an endless belt, but are not particularly limited as long as the surface roughness can be controlled and managed with a uniform material.

  The gel film is usually heated to 20 to 200 ° C., preferably 40 to 150 ° C. by receiving heat from the support and / or receiving heat from a heat source such as hot air or an electric heater, and causes a ring-closing reaction to form a free organic solvent or the like. By drying the volatile matter, it becomes self-supporting and is peeled off from the support.

  The gel film peeled from the support may be stretched. The stretching process is not limited as long as the stretching in the transport direction (MD) and the stretching in the width direction (TD) can be combined at a predetermined magnification. The draw ratio for producing a film having the effect of the present invention is usually 200 ° C. or higher, and MD is usually 1.05 to 1.9 times, preferably 1.1 to 1.6 times. More preferably, it may be 1.1 to 1.5 times. TD is usually 1.1 to 1.5 times X of the magnification of MD, and preferably 1.2 to 1.45 times.

  The film may be heat-treated with hot air and / or an electric heater at a temperature of 250 to 500 ° C. for 15 seconds to 30 minutes.

  The thickness of the film is preferably 5 to 75 μm, preferably 10 to 50 μm, more preferably 20 to 40 μm, and the solid content concentration, the viscosity, and the amount of polymer cast on the support are preferably adjusted.

  It is preferable to further anneal the polyimide film thus obtained. By doing so, thermal relaxation of the film occurs and the heat shrinkage rate can be kept small. The annealing temperature is not particularly limited, but is preferably 200 ° C. or higher and 500 ° C. or lower, more preferably 200 ° C. or higher and 370 ° C. or lower, and particularly preferably 210 ° C. or higher and 350 ° C. or lower. The thermal shrinkage from the annealing treatment can suppress the heat shrinkage rate at 200 ° C. within the above range, which is preferable because the dimensional accuracy is further improved.

  Moreover, in order to give adhesiveness to the obtained polyimide film, the film surface may be subjected to electrical treatment such as corona treatment or plasma treatment or physical treatment such as blast treatment, and these physical treatments are: It can be performed according to conventional methods. The pressure of the atmosphere when performing the plasma treatment is not particularly limited, but is usually in the range of 13.3 to 1330 kPa, preferably 13.3 to 133 kPa (100 to 1000 Torr), and 80.0 to 120 kPa (600 to 900 Torr). The range of is more preferable.

The atmosphere in which the plasma treatment is performed contains at least 20 mol% of an inert gas, preferably contains 50 mol% or more of inert gas, more preferably contains 80 mol% or more, and contains 90 mol% or more. Most preferred is. The inert gas includes He, Ar, Kr, Xe, Ne, Rn, N ₂ and a mixture of two or more thereof. A particularly preferred inert gas is Ar. Furthermore, oxygen, air, carbon monoxide, carbon dioxide, carbon tetrachloride, chloroform, hydrogen, ammonia, tetrafluoromethane (carbon tetrafluoride), trichlorofluoroethane, trifluoromethane, etc. are mixed with the inert gas. May be. Preferred mixed gas combinations used as the plasma treatment atmosphere of the present invention are argon / oxygen, argon / ammonia, argon / helium / oxygen, argon / carbon dioxide, argon / nitrogen / carbon dioxide, argon / helium / nitrogen, argon / Helium / nitrogen / carbon dioxide, argon / helium, helium / air, argon / helium / monosilane, argon / helium / disilane and the like.

Processing power density when a plasma treatment is not particularly limited, 200 W · min / ^{m 2} or more preferably, 500 W · min / ^{m 2} or more is more preferable, 1000W · min / ^{m 2} or more is most preferred. The plasma irradiation time for performing the plasma treatment is preferably 1 second to 10 minutes. By setting the plasma irradiation time within this range, the effect of the plasma treatment can be sufficiently exhibited without accompanying film deterioration. The gas type, gas pressure, and treatment density of the plasma treatment are not limited to the above conditions, and may be performed in the atmosphere.

  In addition, although the polyimide film of this invention is equipped with the specific characteristic and physical property (ratio of a specific protrusion, etc.) as mentioned above, such an aspect can be adjusted by selecting the said conditions etc. suitably. . For example, the specific protrusion ratio on both surfaces of the film can be adjusted by selecting the average particle diameter and the addition amount of inorganic particles added to the polyamic acid solution. In addition, the ratio of such protrusions can be affected by the viscosity of the polyamic acid solution, the surface roughness of the support on which the polyamic acid solution is cast, the film stretch ratio after peeling from the support, and so on. You may adjust a protrusion ratio by selecting. That is, in the present invention, by adjusting the average particle size of inorganic particles, the amount added, the viscosity of the polyamic acid solution, the surface roughness of the support, the stretch ratio of the film, and the like to a predetermined range, It is possible to adjust.

  Since the polyimide film thus obtained is excellent in dimensional stability, surface smoothness, folding characteristics, etc., as will be described later, COF (Chip On Film), particularly high density, wired in a narrow pitch in the film width direction. It can be suitably used for a fine pitch circuit board such as a double-sided COF in which wiring is provided on both sides for mounting and a semiconductor package.

[Copper-clad laminate]
The present invention also includes a copper-clad laminate using (provided) the polyimide film of the present invention described above. In such a copper-clad laminate, a copper layer is formed on at least one surface of the polyimide film, and in particular, a copper layer is formed on both surfaces of the polyimide film.
The manufacturing method of such a copper clad laminated body is not specifically limited, You may follow a conventionally well-known manufacturing method. For example, a method of laminating a layer mainly composed of copper by electroplating on a metal layer mainly composed of nickel chromium formed by sputtering on at least one surface (particularly both surfaces) of a polyimide film is generally used. Is. The copper-clad laminate of the present invention can be obtained, for example, by providing nickel chrome alloy layers on both sides of a polyimide film and forming copper of a predetermined thickness (for example, thickness of 1 to 3 μm) thereon by an electroplating method. .

The present invention also includes a double-sided COF substrate using (provided) the above-described copper-clad laminate of the present invention. The double-sided COF substrate may be a copper-clad laminate provided with a wiring circuit.
The manufacturing method of such a double-sided COF substrate is not particularly limited, and a known method can be used, but in particular, it may be manufactured by a semi-additive method.
As a more specific method, a wiring circuit is patterned using a photolithographic method, a resist layer is peeled off where a wiring is to be formed, and then a wiring is formed on the exposed thin copper layer by electrolytic copper plating, and then a resist layer And a method of removing the thin copper layer and the base metal layer, forming 0.1 to 0.5 μm of tin on the wiring by an electroless tin plating method, and then laminating a solder resist on a necessary portion.

  The present invention includes embodiments in which the above-described configurations are variously combined within the technical scope of the present invention as long as the effects of the present invention are exhibited.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited at all by these Examples.

  In the examples, PPD represents paraphenylenediamine, 4,4′-ODA represents 4,4′-diaminodiphenyl ether, PMDA represents pyromellitic dianhydride, and BPDA represents 3,3 ′, 4. , 4′-diphenyltetracarboxylic dianhydride, DMAc represents N, N-dimethylacetamide, respectively.

[Example 1]
(Making polyimide film)
PPD (molecular weight 108.14), 4,4′-ODA (molecular weight 200.24), BPDA (molecular weight 294.22), PMDA (molecular weight 218.12) are prepared in a molar ratio of 35/65/30/70 And polymerized to a 20 wt% solution in DMAc to obtain a 3500 poise polyamic acid solution. A silica DMAc slurry having an average particle diameter of 0.1 μm was added to this by 0.5% by weight per resin weight, and the mixture was sufficiently stirred and dispersed. Next, a 125 μm thick polyester film (Lumirror X43: manufactured by Toray, Ra 0.2 μm) was placed on the glass plate as a support, and the polyamic acid solution was placed on the support and cast with an applicator. Subsequently, this was immersed in a mixed solution of acetic anhydride and β-picoline for 10 minutes to cause an imidization reaction, and then the polyimide gel film was peeled off from the polyester film, and the gel film was applied in the applicator direction (hereinafter referred to as MD) with a manual stretcher. ) And 1.40 times in the vertical direction (hereinafter referred to as TD), and then fixed to the support frame. Then, after drying at 300 ° C. for 20 minutes and then at 400 ° C. for 5 minutes, it was removed from the support frame to obtain a polyimide film having a thickness of 35 μm.

The film was evaluated for the following properties, and Table 1 shows the results.
(1) Surface roughness It measured according to JIS B0601-1982 using surface roughness measuring machine SE-3500 (made by Kosaka Laboratory).
(2) Number of surface protrusions Using a laser microscope VK-9710 (manufactured by Keyence), the protrusions on the surface of the film were observed in a field of 100 cm ² and the height was measured, and the number of protrusions of 0.8 μm or more was counted.
The observation was performed by magnifying the measurement site 10 times with an objective lens (at a magnification of 200 times on the monitor). In addition, the width of the observed protrusion is 15 μm or more (no protrusion having a width of less than 15 μm), and when the protrusion has a plurality of protrusions, the height of the highest protrusion is set to the height of the protrusion. Say it.
(3) Coefficient of thermal expansion TMA-60 (manufactured by Shimadzu Corporation) was used, and measurement was performed under the conditions of measurement temperature range: 50 to 200 ° C, temperature increase rate: 10 ° C / min.
(4) Tensile modulus RTM-250 (manufactured by A & D) was used, and the tensile modulus was measured under the condition of 100 mm / min.
(5) Loop stiffness A loop stiffness tester DA (manufactured by Toyo Seiki Seisakusho) was used, and measurement was performed under the conditions of a sample width of 20 mm, a loop length of 50 mm, and a compression distance of 20 mm.
(6) Film handling property The sample support surface and non-support surface are overlapped and fixed on a slip tester (manufactured by Techno Needs), and the static friction coefficient and dynamic friction coefficient are measured at a load of 200 g and a measurement speed of 120 mm / min. It was measured. The results are shown in Table 1.

(Creation of double-sided copper-clad laminate)
After forming a nickel chrome layer (Ni: Cr = 80: 20 m, thickness 25 nm) and a copper layer (thickness 100 nm) on the support surface of the polyimide film obtained above by sputtering, similarly, the non-support surface Also, a nickel chromium layer and a copper layer were formed. Subsequently, a copper layer having a thickness of 2 μm was formed on both surfaces by electrolytic plating using a copper sulfate plating solution.

  The following items were evaluated for the obtained double-sided copper-clad laminate (FIG. 1). The results are listed in Table 1.

(7) Number of pinholes After the support surface of the double-sided copper-clad laminate was protected with a cover film, an etching treatment was performed using a ferric chloride solution to remove the copper layer and the nickel chromium layer on the non-support surface. Subsequently, in a dark room, the fluorescent lamp backlight is illuminated from the polyimide surface (non-support surface), and the number of light (pinholes) leaking to the copper surface (support surface) is visually counted in a 100 cm ² field of view. It was. In the same manner, the number of pinholes on the non-support surface was also evaluated.

(Creation of evaluation COF substrate)
About the sample which removed the copper layer of the non-supporting body surface of the double-sided copper clad laminated board obtained above, and the nickel chromium layer, the copper surface (supporting body surface) is made into 15% of water by using Sulcup ACL-067 made by Uemura Kogyo Co., Ltd. After impregnating the diluted solution for 30 seconds at 30 ° C. and degreasing, a photoresist is laminated so that the dry thickness is 15 μm, and the pattern for evaluation (line width 20 μm, space width 20 μm) shown in FIG. Developed. Then, according to a conventional method, a copper plating layer having a thickness of 8 μm was formed by a semi-additive method, and an evaluation COF substrate was prepared.
The obtained COF substrate was evaluated for the following items, and the results are shown in Table 1.

(8) Bending property The conductor side of the COF substrate was bent inward as shown in FIG. 3 and a load of 1.0 kgf was applied for 10 seconds, and then the COF substrate was opened and returned to its original state. This was defined as one cycle, and was repeated 5 to 30 times. During that time, the bent part of the conductor was observed with a microscope, and the number of times until the conductor broke was measured.

(9) Dimensional stability Using the anisotropic COF film (ACF: product name, Anisolum C5311 manufactured by Hitachi Chemical Co., Ltd.) on the adherend (glass), the evaluation COF substrate obtained above is 180 ° C. × 10 seconds, 5 MPa. Crimping was performed under the conditions (FIG. 4).

The external dimensions of 30 sample circuit patterns for evaluation were measured before (L3) and after (L4) pressure bonding, and the standard deviation of the elongation calculated by the following equation was measured.
Elongation rate (%) = {(L4-L3) / L3} × 100

[Example 2]
A polyimide film having a thickness of 38 μm was obtained in the same procedure as in Example 1 except that the gel film was stretched 1.25 times in MD and 1.40 times in TD.

[Example 3]
A polyimide film having a thickness of 35 μm was obtained in the same procedure as in Example 1, except that a silica DMAc slurry having an average particle diameter of 0.4 μm was used.

[Example 4]
A polyimide film having a thickness of 25 μm was obtained in the same procedure as in Example 3 except that the gel film was stretched 1.15 times in MD and 1.35 times in TD.

[Example 5]
The thickness of PPD, 4,4′-ODA, BPDA, and PMDA is set to a ratio of 20/80/35/65 and silica having an average particle diameter of 0.4 μm is used. A polyimide film having a thickness of 38 μm was obtained.

[Example 6]
A polyimide film having a thickness of 38 μm was obtained in the same procedure as in Example 3 except that PPD, 4,4′-ODA, BPDA, and PMDA were used in a molar ratio of 30/70/25/75.

[Example 7]
A polyimide film having a thickness of 25 μm was obtained in the same procedure as in Example 5 except that calcium hydrogen phosphate having an average particle diameter of 1.0 μm was used.

[Example 8]
A polyamic acid solution was prepared by adding PDM and BPDA at a molar ratio of 1: 1 and adding 0.5% by weight of silica DMAc slurry having an average particle diameter of 0.1 μm to the resin weight. Then, a polyimide film having a thickness of 38 μm was obtained in the same procedure as in Example 4 except that a polyester film having a thickness of 125 μm (Lumirror S10: manufactured by Toray, Ra 0.05 μm) was used as the support.

[Example 9]
A polyimide film having a thickness of 35 μm was obtained in the same procedure as in Example 3 except that PPD, 4,4′-ODA, BPDA, and PMDA were used in a molar ratio of 40/60/25/75.

[Example 10]
A polyimide film having a thickness of 35 μm was obtained in the same procedure as in Example 3 except that PPD, 4,4′-ODA, BPDA, and PMDA were used in a molar ratio of 45/55/35/65.

  The polyimide films obtained in Examples 2 to 8 and the double-sided copper-clad laminates and COF substrates for evaluation that were prepared in the same procedure as in Example 1 were evaluated for the characteristics in the same manner as in Example 1. Table 1 shows the results.

  From the result of the said table | surface, it can be said that the polyimide film of an Example is a film excellent in surface smoothness, dimensional stability, bendability, etc. Moreover, since it was excellent in the balance of the surface smoothness of both surfaces of a film, it was confirmed that the film was easy to handle and could maintain high productivity.

  The polyimide film of the present invention is excellent in dimensional stability, bending characteristics, and the like. In the present invention, a film having high surface quality on both sides can be obtained. Therefore, such a polyimide film of the present invention can be suitably used for a fine pitch circuit board such as a double-sided COF in which wiring is provided on both sides for the purpose of high-density mounting and a semiconductor package.

Claims (12)

A polyimide film containing inorganic particles, the ratio of protrusions having a height of 0.8 μm or more on one surface a of the film being A / 100 cm ² , and protrusions having a height of 0.8 μm or more on the other surface b of the film A double-sided COF polyimide film in which both A and B are 10 or less when the ratio of B / 100 cm ² is used. A polyimide film containing inorganic particles, the ratio of protrusions having a height of 0.8 μm or more on one surface a of the film being A / 100 cm ² , and protrusions having a height of 0.8 μm or more on the other surface b of the film A polyimide film in which the absolute value of the difference between A and B is 2 or more when the ratio of B / 100 cm ² is used.   The polyimide film according to claim 1, wherein A and / or B is 2 or more.   The polyimide film according to any one of claims 1 to 3, wherein the surface roughness Ra is 0.01 to 0.05 µm and the surface roughness Rz is 0.05 to 0.6 µm on both the surface a and the surface b.   The polyimide film according to any one of claims 1 to 4, wherein the thermal expansion coefficient in the MD direction is 4 to 10 ppm / ° C, and the thermal expansion coefficient in the TD direction is 0 to 8 ppm / ° C.   The polyimide film according to any one of claims 1 to 5, which satisfies a tensile elastic modulus of 5 to 10 GPa and / or a loop stiffness of 10 to 75 mN / cm.   The polyimide film in any one of Claims 1-6 comprised with the polyimide which uses the aromatic diamine component containing paraphenylenediamine, and an acid anhydride component as a polymerization component.   The polyimide film according to claim 1, wherein the average particle diameter of the inorganic particles is 0.05 to 0.5 μm.   The double-sided copper clad laminated board using the polyimide film in any one of Claims 1-8.   The double-sided copper-clad laminate according to claim 9, wherein the copper thickness is 1 to 3 µm.   A double-sided COF substrate using the double-sided copper-clad laminate according to claim 9 or 10.   A method for producing a double-sided COF substrate by a semi-additive method using the double-sided copper-clad laminate according to claim 9 or 10.