JP2010186874A - Method of manufacturing flexible printed wiring board material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed wiring board material for a COF formed into warpage setting a conductive layer on the inside without being influenced by moisture absorption or water absorption of a base film, and a method of manufacturing the same, in a method of manufacturing a flexible printed wiring board material. <P>SOLUTION: This method of manufacturing a flexible printed wiring board material includes (1) a process of forming a metal seed layer on a polyimide film by a dry plating method by using a polyimide film exhibiting a linear expansion coefficient having a value smaller than that of a linear expansion coefficient of a conductor layer to be formed, and (2) a process of forming the conductor layer by a wet plating method on a metal seed layer provided by the process (1). In the process (2), time until the thickness of the conductor layer to be formed exceeds 1 μm is less than 5 min, and transport tensile force is 8 N/cm or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flexible printed wiring board material that can be suitably used mainly for chip-on-film (hereinafter also referred to as COF) applications and a method for producing the same.

  Currently, liquid crystal driver ICs are mainly mounted by a chip-on-film method (COF method) or the like, and a flexible printed wiring board material (hereinafter also referred to as FCCL) used is mainly, for example, physical vapor deposition. A method in which a metal seed layer is directly formed on a polyimide film by a dry plating method typified by a method (hereinafter also referred to as a PVD method), and then a conductor layer is formed on the seed layer by a wet plating method. It is produced by the method.

  By the way, the polyimide film has a characteristic that it expands when heat is applied and also expands when it absorbs moisture or absorbs water. Accordingly, when the flexible printed wiring board material is manufactured, the polyimide film and the conductor layer are expanded at their respective expansion rates. In this expanded state, when the temperature and humidity are lowered, each of them is contracted to almost the original state.

  Therefore, for example, if the linear expansion coefficient of the polyimide film is smaller than that of the conductor layer, the polyimide film is integrated with the conductor layer in an expanded state smaller than the expansion of the conductor layer due to heat. Since the shrinkage of the polyimide film after the temperature of the wiring board material decreases is smaller than the shrinkage of the conductor layer (the shrinkage of the conductor layer is greater), the flexible printed wiring board material results in the conductor layer side inside. The warped will occur. It is known that the warp generated in the flexible printed wiring board material may cause problems during subsequent circuit formation and IC mounting. Therefore, various methods have been proposed for controlling the direction of warping and the amount of warping of the flexible printed wiring board material by controlling the linear expansion coefficient of the polyimide film serving as the base film according to the application used (for example, (See Patent Documents 1 and 2).

  In general, a flexible printed wiring board material for COF is required to have high dimensional stability with respect to a base film as the density of wiring increases. In particular, in the process of mounting the liquid crystal driver IC on the COF film carrier tape, high positional accuracy is required, and the driver IC may be mounted while the COF film carrier tape is fixed by vacuum suction. In this case, it is preferable that the film carrier tape for COF used for them is warped inward on the conductor layer side. In order to generate the warp with the conductor layer on the inside as described above, it can be achieved by making the linear expansion coefficient of the base film smaller than the linear expansion coefficient of the conductor layer.

  However, when using a polyimide film that tends to undergo dimensional changes due to moisture absorption / desorption and dehydration of the film, the flexible printed wiring board material for COF produced by the PVD method has a wet plating process in its production process. Even if the linear expansion coefficient of the base film is smaller than that of the conductor layer, the warp with the conductor layer on the inside as described above may not occur. When a flexible printed wiring board material for COF manufactured using such a polyimide film is used, in other words, when a warped COF film carrier tape with a conductor layer on the outside is used, a vacuum is applied when mounting a liquid crystal driver IC. When fixing the film carrier tape for COF by adsorption, there is a problem that the film carrier tape cannot be fixed.

Japanese Patent No. 3356560 Japanese Patent No. 3912610

  In the manufacturing method of the flexible printed wiring board material, when using a polyimide film that easily undergoes dimensional changes due to moisture absorption or water absorption of the film, the influence of these dimensional changes is suppressed, and the warp with the conductor layer inside It aims at providing the manufacturing method of a flexible printed wiring board material, and the film carrier tape for COF using the same.

  As a result of intensive investigations in view of the above problems, the present inventors have suppressed the influence of moisture absorption and water absorption of the base film by using the following manufacturing method, so that the conductor layer is warped inside. The present inventors have found that a flexible printed wiring board material can be provided and completed the present invention.

  That is, the first of the present invention uses a polyimide film having a linear expansion coefficient smaller than the linear expansion coefficient of the conductor layer to be formed, and (1) a metal seed layer is formed on the polyimide film by dry plating. In the method for producing a flexible printed wiring board material, comprising: a step of forming; and (2) a step of forming a conductor layer by a wet plating method on the metal seed layer obtained in the step (1). The method for producing a flexible printed wiring board material is characterized in that the time until the thickness of the formed conductor layer exceeds 1 μm is 5 minutes or less and the transport tension is 8 N / cm or less.

  In a preferred embodiment, in the step (2), the time until the thickness of the formed conductor layer exceeds 1 μm is 2.5 minutes or less. .

  In a preferred embodiment, the polyimide film has pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, paraphenylenediamine, 4,4′-oxydianiline, 2, 2-bis (4-aminophenoxyphenyl) propane is an essential component, the elastic modulus is 5 to 10 GPa, the average linear expansion coefficient at 100 to 200 ° C. is 5 to 15 ppm / ° C., and the temperature is 40 to 50 ° C. Film dimensions when the hygroscopic expansion coefficient is 5 to 15 ppm /% RH with a humidity change of 70% RH, and the humidity is changed from 40% RH to 70% RH at a temperature within 10 minutes at a temperature of 50 ° C. The method according to any one of the above-mentioned flexible printed wiring board materials, wherein the change rate is within 30 minutes.

  In a preferred embodiment, the metal seed layer formed on the polyimide film in the step (1) is at least one selected from Ni, Cu, Mo, Ta, Ti, V, Cr, Fe, Co, Al, and Sn. And the conductor layer formed by the wet plating method in step (2) is Cu, and relates to the method for producing a flexible printed wiring board material according to any one of the above.

  A preferred embodiment is a flexible printed wiring board material manufactured by any one of the methods described above, wherein the warping amount of a sample obtained by cutting the wiring board material into a size of 35 × 35 mm has a temperature of 20 to 40 ° C. The present invention relates to a flexible printed wiring board material having a conductor layer of 10 mm or less in an environment of a humidity of 40 to 60% RH.

  2nd of this invention is related with the film carrier tape for chip-on-films using the flexible printed wiring board material manufactured by the manufacturing method in any one of the said.

  According to the method for producing a flexible printed wiring board of the present invention, there is provided a flexible printed wiring board material that suppresses the influence of dimensional change due to moisture absorption or water absorption of the base film and causes warping with the conductor layer inside. be able to.

  Hereinafter, an embodiment of the present invention will be described in detail.

  First, a polyimide film that can be used in the present invention will be described. Generally, polyimide can be obtained from its precursor polyamic acid (also referred to as polyamic acid), and in the present invention, any known method can be used for producing the polyamic acid.

  Usually, an aromatic acid dianhydride and an aromatic diamine are dissolved in an organic solvent in a substantially equimolar amount, and the resulting polyamic acid solution is mixed with the acid dianhydride under controlled temperature conditions. Produced by stirring until the polymerization of the diamine is complete. These polyamic acid solutions are usually obtained at a concentration of 5 to 35% by weight, preferably 10 to 30% by weight. When the concentration is in this range, an appropriate molecular weight and solution viscosity can be obtained.

Any known method can be used as the polymerization method, and the following method is particularly preferable as the polymerization method. That is,
A method in which an aromatic diamine is dissolved in an organic polar solvent, and this is reacted with a substantially equimolar amount of an aromatic tetracarboxylic dianhydride for polymerization.
An aromatic tetracarboxylic acid and an excess molar amount of the aromatic diamine compound are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding an aromatic diamine compound here, using the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps. How to react.
An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Then, the method of superposing | polymerizing using an aromatic diamine compound so that an aromatic tetracarboxylic dianhydride and an aromatic diamine compound may become substantially equimolar in all the processes.
A method in which an aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent and then polymerized using an aromatic diamine compound so as to be substantially equimolar.
A method of polymerizing by reacting a substantially equimolar mixture of aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent.
And so on.

  In the present invention, polyamic acid obtained by any of the above methods may be used, and the polymerization method is not particularly limited. In the present invention, the effect can of course be obtained even if the molecular arrangement in the polymer is controlled or an expensive monomer is used.

  Among these methods, from the viewpoint of stably controlling the process, all the aromatic diamine components used in all processes are dissolved in an organic solvent, and then the aromatic diamine component is added so as to be substantially equimolar. It is more preferable to use a method of conducting a polymerization reaction.

  Next, materials used for producing the polyamic acid will be described. Suitable acid dianhydrides that can be used in the present invention are pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetra. Carboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'- Benzophenone tetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-peritetracarboxylic dianhydride, bis (3,4- Dicarboxyphenyl) propanoic dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethanoic dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4 -Dicarboxyphenyl) Including ruphone dianhydride, p-phenylene bis (trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride) and derivatives thereof, alone or in a mixture of any proportion It can be preferably used.

  Among these acid dianhydrides, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid The use of anhydrides is preferred. Furthermore, it is more preferable to use 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride or pyromellitic dianhydride. These can be used alone or in combination with other acid dianhydrides. The preferred amount used is 10 to 70 mol%, preferably 15 to 70 mol%, more preferably 15 to 60 mol% of pyromellitic dianhydride, and / or 3,3 ′ based on the total acid dianhydride. , 4,4'-benzophenonetetracarboxylic dianhydride is used in an amount of 10 to 50 mol%, preferably 15 to 50 mol%, more preferably 15 to 40 mol%, based on the total acid dianhydride. If 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride is less than this use range, the resulting polyimide film may have poor mechanical properties and the like. Moreover, when it exceeds this range, the glass transition temperature tends to be too low, and defects may occur in the baking process of film production. Moreover, when pyromellitic dianhydride is less than this use range, the glass transition temperature tends to be too low, which may cause problems in the baking process of film production. On the other hand, if it exceeds this range, the resulting polyimide film may have poor mechanical properties and the like.

  In the present invention, suitable diamine components that can be used for the production of polyamic acid, which is a polyimide precursor, include p-phenylenediamine, o-phenylenediamine, 4,4′-diaminodiphenylpropane, and 4,4′-diaminodiphenylmethane. 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfone, 4,4′-oxydianiline, 3,3′-oxydianiline, 3,4 ′ -Oxydianiline, 4,4'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4 '-Diaminodiphenyl N-phenylamine, 1,4-diaminobenzene Zen (p-phenylenediamine), bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (3-aminophenoxy) phenyl} sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 3,3′-diaminobenzophenone, 4, Examples thereof include 4′-diaminobenzophenone and 2,2-bis (4-aminophenoxyphenyl) propane, and these can be used alone or in combination. These examples are examples that are suitably used as the main component, and any diamine can be used as the accessory component. Examples of diamines that can be particularly preferably used among these include p-phenylenediamine, o-phenylenediamine, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2 , 2-bis (4-aminophenoxyphenyl) propane, 4,4′-oxydianiline, 3,3′-oxydianiline, 3,4′-oxydianiline. Of these diamines, 2,2-bis (4-aminophenoxyphenyl) propane, 4,4′-oxydianiline, and p-phenylenediamine are particularly preferable. These can be used alone or in combination with other diamines.

  Preferable amounts of 4,4′-oxydianiline and p-phenylenediamine are 10 to 70 mol%, preferably 15 to 70 mol%, more preferably 15 to 60 mol%, based on the total diamine compound. If the amounts of p-phenylenediamine and 4,4′-oxydianiline are out of this range, the resulting polyimide film may have inferior mechanical properties. It may occur. In addition to the above two diamines, 2,2-bis (4-aminophenoxyphenyl) propane can be used as appropriate. The preferred amount to be used is 10 to 50 mol%, preferably 20 to 40 mol%, based on the total diamine compound. If the amount of 2,2-bis (4-aminophenoxyphenyl) propane used exceeds this range, the glass transition temperature tends to be too low, and problems may occur in the baking process of film production. Further, if the amount of 2,2-bis (4-aminophenoxyphenyl) propane used is below this range, the hygroscopic expansion coefficient of the film tends to increase, and the effects of the present invention can be achieved even when other mechanical properties are good. There are cases where it does not fully perform.

  Next, as the preferred solvent for synthesizing the polyamic acid, any solvent that dissolves the polyamic acid can be used, but amide solvents, that is, N, N-dimethylformamide, N, N-dimethyl are used. Examples thereof include acetamide and N-methyl-2-pyrrolidone, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

  Further, for the purpose of improving various properties of the film such as slipperiness, slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness, a filler can be added, for example, in the polyamic acid solution. Any filler may be used, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

  The particle size of the filler is not particularly limited because it is determined by the film properties to be modified and the type of filler to be added, but generally the number average particle size is 0.05 to 100 μm, preferably 0.8. It is 1 to 75 μm, more preferably 0.1 to 50 μm, and particularly preferably 0.1 to 25 μm. If the particle diameter is less than this range, it is difficult for a modification effect such as slipperiness to appear, and conversely if it exceeds this range, the surface properties may be greatly impaired or the mechanical properties may be greatly deteriorated. Further, the number of added parts of the filler is not particularly limited because it is determined by the film properties to be modified, the filler particle diameter, and the like. Generally, the addition amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight with respect to 100 parts by weight of the polyimide. If the amount of filler added is less than this range, the effect of modification by the filler hardly appears, and if it exceeds this range, the mechanical properties of the film may be greatly impaired.

The addition of the filler is
1. 1. A method of adding to a polymerization reaction solution before or during polymerization 2. A method of kneading fillers using three rolls after the completion of polymerization. Any method such as preparing a dispersion containing filler and mixing it with a polyamic acid organic solvent solution may be used, but a method of mixing a dispersion containing filler with a polyamic acid solution, particularly immediately before film formation. This method is preferable because the contamination by the filler in the production line is minimized. When preparing a dispersion containing a filler, it is preferable to use the same solvent as the polymerization solvent for the polyamic acid. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, a dispersant, a thickener and the like can be used within a range not affecting the film physical properties.

In particular, when added for improving the slipperiness of the base film for a flexible printed wiring board for COF, the average particle size is preferably 0.1 to 5 μm, more preferably 0.1 to 1 μm. When the particle diameter is below this range, the effect of slipping is hardly exhibited, and when it exceeds this range, it tends to be difficult to produce a high-definition wiring pattern. Further, in this case, the dispersion state of the filler is also important, and it is preferable that the aggregate of fillers of 10 μm or more is 50 pieces / m ² or less in the polyimide film, more preferably 40 pieces / m ² or less. When there are more filler aggregates of 10 μm or more than this range, when a high-definition wiring pattern is formed, the adhesion area tends to be reduced and reliability tends to be lowered.

  As a method for producing a polyimide film from the above-described polyamic acid solution, a conventionally known method can be used. Examples of this method include a thermal imidization method and a chemical imidization method, and either method may be used to produce a film. However, it is more preferable to use imidization by a chemical imidization method because it tends to obtain a polyimide film having various characteristics suitably used in the present invention.

In the present invention, the production process of the polyimide film,
a) a step of reacting an aromatic diamine and an aromatic tetracarboxylic dianhydride in an organic solvent to obtain a polyamic acid solution;
b) casting a film-forming dope containing the polyamic acid solution on a support;
c) a step of peeling the gel film from the support after heating on the support;
d) further heating to imidize and dry the remaining amic acid,
It is particularly preferable that

  In the above step, a curing agent containing a dehydrating agent typified by an acid anhydride such as acetic anhydride and an imidation catalyst typified by a tertiary amine such as isoquinoline, β-picoline or pyridine may be used. .

  Hereinafter, a preferred embodiment of the present invention, a chemical imidization method, will be described as an example, and the production process of a polyimide film will be described. The film forming conditions and heating conditions may vary depending on the type of polyamic acid, the thickness of the film, and the like. Is.

First, a film forming dope is obtained by mixing a dehydrating agent and an imidization catalyst in a polyamic acid solution at a low temperature. Subsequently, this film-forming dope is cast into a film on a support such as a glass plate, an aluminum foil, an endless stainless steel belt, or a stainless drum, and the temperature on the support is 80 ° C. to 200 ° C., preferably 100 ° C. to 180 ° C. Heating in the region activates the dehydrating agent and the imidization catalyst. In this way, after the amic acid is partially cured and / or dried, a polyamic acid film (hereinafter also referred to as a gel film) partially peeled from the support and imidized partially is obtained. The gel film is in an intermediate stage of curing from polyamic acid to polyimide, has a self-supporting property, and the volatile content calculated from the following formula (1) is in the range of 5 to 500% by weight, preferably 5 to 200. % By weight, more preferably in the range of 5 to 150% by weight.
(AB) × 100 / B (1)
In formula (1), A and B represent the following.
A: Weight of gel film B: Content of volatile matter because defects such as film breakage, film color unevenness due to drying unevenness, characteristic variation, etc. may occur in the weight baking process after heating the gel film at 450 ° C. for 20 minutes However, it is preferable to use a film in this range.

  The preferable amount of the dehydrating agent is 0.5 to 5 mol, preferably 1.0 to 4 mol, based on 1 mol of the amic acid unit in the polyamic acid. Moreover, the preferable quantity of an imidation catalyst is 0.05-3 mol with respect to 1 mol of amic acid units in a polyamic acid, Preferably it is 0.2-2 mol. If the dehydrating agent and the imidization catalyst are below the above ranges, chemical imidization may be insufficient, and may break during firing or mechanical strength may decrease. Moreover, when these amounts exceed the above range, the progress of imidization becomes too fast and it may be difficult to cast into a film.

  The end of the gel film is fixed and dried while avoiding shrinkage during curing, water, residual solvent, residual dehydrating agent and imidization catalyst are removed, and the remaining amic acid is completely imidized, The polyimide film of the invention can be obtained.

  At this time, it is preferable to finally heat at a temperature of 400 to 650 ° C. for about 5 to 400 seconds. Above this temperature and / or for a long time, thermal degradation of the film can occur and problems can occur. Moreover, in order to relieve the internal stress remaining in the film, heat treatment can be performed under the minimum tension necessary for transporting the film. This heat treatment may be performed in the film manufacturing process, or may be provided separately. The heating conditions vary depending on the characteristics of the film and the apparatus used, and therefore cannot be determined in general. However, it is generally 200 ° C. or higher and 500 ° C. or lower, preferably 250 ° C. or higher and 500 ° C. or lower, particularly preferably 300 ° C. or higher. The internal stress can be relaxed by heat treatment at a temperature of 450 ° C. or lower for 1 to 300 seconds, preferably 2 to 250 seconds, particularly preferably 5 to 200 seconds.

  Here, the various characteristics in this invention of the obtained polyimide film are demonstrated. The average linear expansion coefficient of the polyimide is preferably lower than the average linear expansion coefficient of the conductor layer. More preferably, for example, the average linear expansion coefficient at 100 to 200 ° C. measured with a TMA apparatus (TMA120C) manufactured by Seiko Electronics Co., Ltd. is in the range of 1 to 15 ppm / ° C., more preferably 5 to 15 ppm / ° C. It is a range. If the average linear expansion coefficient exceeds the above range, the conductor layer becomes warped without being affected by film moisture absorption or water absorption. Conversely, if the average linear expansion coefficient is below the above range, the film becomes brittle and can be processed by continuous processing. There is no fear. Moreover, if the elasticity modulus of the polyimide film obtained by the above-mentioned method is a range which does not receive the deformation | transformation of the film by the influence of the conveyance in the continuous process (2) wet-plating process similarly to an average linear expansion coefficient. Although it does not specifically limit, Preferably it is 4 GPa or more, More preferably, it is 5-10 GPa.

  Important characteristics for exerting the effects of the present invention include a hygroscopic expansion coefficient and a dimensional change rate due to water absorption of the film. Here, the hygroscopic expansion coefficient and the dimensional change rate of the film in the present invention can be specifically calculated by the following method.

  The above hygroscopic expansion coefficient is 40% so that the change is within 10 minutes in a state where the sample size is 5 mm wide, 15 mm long, the load is 5 g and the temperature is held at 50 ° C. using a TMA apparatus with a water vapor system. It is calculated from the expansion amount of the film accompanying the change from RH to 70% RH.

  The above dimensional change rate is 40% RH so that the change will be within 10 minutes with a sample size: width 5 mm, length 15 mm, load 5 g and temperature held at 50 ° C. using a TMA device with a steam system. Is calculated by calculating the time until the expansion of the film due to TMA at that time reaches a stable region. The above-mentioned “film expansion reaches a stable region” means that a state in which the dimensional change of the film caused by TMA is equal to or less than “0.1 μm / H” is determined as “the stable region has been reached”. Good.

  The hygroscopic expansion coefficient of the preferable film by the above calculation is 15 ppm /% RH or less, and more preferably in the range of 5 to 15 ppm /% RH. The dimensional change rate due to water absorption of the film is preferably within 60 minutes. More preferably, it is within 30 minutes.

  Next, (1) a step of forming a seed layer on the polyimide film by a dry plating method in the method for producing a flexible printed wiring board material, and (2) wet plating on the seed layer obtained in the step (1). The step of forming the conductor layer will be described.

  In the conductor layer forming treatment described below, it is preferable that the film piece obtained by cutting the above-described polyimide film is disassembled, continuously processed and wound up as a metallized polyimide film roll.

(1) Process For dry plating, any known method such as sputtering, vapor deposition, ion plating, and chemical vapor deposition (CVD) can be used. Of these, sputtering is more preferable. Although the sputtering method is not particularly limited, direct current bipolar sputtering, high frequency sputtering, magnetron sputtering, counter target sputtering, ECR sputtering, bias sputtering, plasma controlled sputtering, multi-target sputtering, and the like can be used. There are no particular restrictions on the output during sputtering processing, the gas pressure for generating plasma, and the processing temperature, as long as the sputtering apparatus can handle them. The output is usually 10 to 1000 W, the gas pressure is usually 0.01 to 10 Pa, and the temperature is usually 20 ° C. to 400 ° C., preferably 100 to 300 ° C. The film forming rate is 0.1 to 1000 Å / second, preferably 1 to 100 Å / second. If the film formation rate is too high, the adhesion between the film and the seed layer may be reduced.

  When forming a conductor layer on the surface of a polyimide film as a substrate, first, at least one selected from Ni, Cu, Mo, Ta, Ti, V, Cr, Fe, Co, Al, and Sn is used as a base (seed layer). It is preferable to contain, and it is preferable that many Ni, Cr, Mo, and Al are included from a viewpoint of the adhesiveness of a film and a seed layer. Further, the thickness of the base is 20 to 2000 mm, preferably 40 to 1000 mm, and more preferably 40 to 500 mm. If it exceeds 2000 mm, it takes too much time for production, so it is not practical. In dry plating, the film being formed is preferably maintained at 100 to 400 ° C, more preferably 150 to 350 ° C. Below this temperature, pinholes may occur during the formation of the seed layer. Conversely, when this temperature is exceeded, thermal degradation of the film may occur, causing problems. In addition, from the viewpoint of adhesion to the seed layer before film formation by dry plating, the polyimide film surface is treated with a coupling agent, sandblasting, holeing, corona treatment, plasma treatment, chemical treatment etching, etc. You may use for.

(2) Process As a conductor layer formed on the seed layer of the metallized polyimide film by the wet plating method, Cu (linear expansion coefficient is approximately 17 ppm / ° C.) is preferable, and the thickness is preferably 1 to 12 μm, more preferably. 1-9 μm. When the thickness of the conductor layer is greater than 12 μm, the influence of the etching rate difference due to the difference in the seed layer metal species is large, and there is a tendency that defects are likely to occur at the time of pattern creation. Also suitable for COF applications where a narrow pitch wiring pattern is required. There may be no.

  For example, electroplating or electroless plating can be used for forming the conductor layer by wet plating in the step (2). As the electroplating method, copper pyrophosphate plating or copper sulfate plating can be preferably used. Regarding the wet plating process, it is preferable that the metallized polyimide film wound up as a roll after dry plating is continuously processed to be wound up as a final flexible printed wiring board material. Further, (2) the transport tension in the wet plating step is 8 N / cm or less, preferably 1 N / cm or more and 8 N / cm or less. If transport is performed in a state where the tension exceeds 8 N / cm, the polyimide film may be elastically deformed, and the effects of the present invention may not be exhibited. Further, when the transport tension is less than 1 N / cm, (2) transport in the wet plating process may be difficult.

  When the conductor layer is formed on the seed layer of the metallized polyimide film by the wet plating method in the step (2) in the present invention, the conductor layer is formed on the seed layer obtained in the step (1). As the thickness increases, the dimensional change of the polyimide film based on moisture absorption and water absorption is considered to be suppressed due to the influence of the conductor layer. It is preferable that the timing at which the dimension of the polyimide film as the base film is fixed is faster than the film being transported is completely expanded due to water absorption. In other words, when the conductor layer is laminated in a state where the film has sufficiently absorbed water and the film has expanded and the dimensions thereof are fixed, the warp of the produced flexible printed wiring board material becomes the warp with the conductor layer on the outside. As a result, the object of the present invention may not be achieved. Specifically, in the (2) wet plating step, the time until the conductor layer is laminated on the seed layer and the dimension of the polyimide film is fixed is not faster than the dimensional change rate of the film. Must not. From this viewpoint, it is preferable that the time until the dimensions of the polyimide film are fixed is within 5 minutes.

  Here, the time until the dimension of the polyimide film is fixed in the present invention refers to the time until the thickness of the conductor layer exceeds 1 μm in the wet plating step. If the time until the thickness of the conductor layer exceeds 1 μm in the wet plating process exceeds 5 minutes, the conductor layer is laminated without fixing the dimensions of the film, and as a result, the film continued to expand. A conductor layer will be formed in a state, and the effect of this invention may not be exhibited. In the (2) wet plating step in the present invention, the preferred time until the thickness of the conductor layer exceeds 1 μm is 5 minutes or less, more preferably 2.5 minutes or less.

  Before the wet plating process in the step (2) in the present invention, a chemical solution such as hypochlorite ion for the purpose of cleaning the seed layer of the metalized polyimide film may be performed. Moreover, it is preferable to heat-process the metallized polyimide film obtained after the conductor layer was formed by wet plating in the range of 100 degreeC-350 degreeC. This heat treatment is more preferably performed at 120 to 330 ° C, particularly preferably 150 to 300 ° C. The distortion which the base film has and the distortion which arises in the manufacturing process of a metallized polyimide film are relieved by this heat treatment, and the effect of the present invention can be expressed more effectively. When the heat treatment temperature is less than 100 ° C., the effect of alleviating the strain becomes small. Conversely, when the heat treatment temperature exceeds 350 ° C., the base polyimide film may be deteriorated.

  The amount of warpage of the flexible printed wiring board material obtained after completion of the wet plating in the step (2) in the present invention can be measured by the following method. A sample obtained by cutting a flexible printed wiring board material into a 35 mm × 35 mm square is held in an environment of a temperature of 20 to 40 ° C. and a humidity of 40 to 60% RH, and the height of the four corners of the sample is raised using a height gauge. Measure the height and calculate the average value of the floating height.

  The flexible printed wiring board material obtained by the production method of the present invention preferably not only exhibits warp with the conductor layer as the inside, but also the amount of warp is important. Preferably, the warpage is 10 mm or less. If this amount of warpage is exceeded, defects tend to occur during pattern creation. Moreover, the optimal use environment of the flexible printed wiring board material obtained by the manufacturing method of this invention is temperature 20-40 degreeC from a viewpoint that the obtained flexible printed wiring board becomes the curvature which set the conductor layer inside. It is preferably carried out in an environment with a humidity of 40 to 60% RH. Below this environmental range, the warping behavior is caused with the conductor layer inside, but the curl amount may deviate from the desired range.

  The flexible printed wiring board material thus obtained is used as a film carrier tape such as a flexible printed wiring board (FPC), a TAB tape, and a COF tape. In particular, for example, a flexible printed wiring board material suitable for a film carrier tape for COF is used because the conductor layer side warps when placed in an environment of temperature 20 to 40 ° C. and humidity 40 to 60% RH. Obtainable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to an Example.

(Average linear expansion coefficient)
The linear expansion coefficient at 100 to 200 ° C. is measured by using a TMA120C manufactured by Seiko Electronics Co., Ltd., and the temperature is temporarily raised to 10 to 400 ° C. at 10 ° C./min with a sample size of 3 mm in width and 10 mm in length and a load of 3 g. Then, it was cooled to 10 ° C., further heated at 10 ° C./min, and calculated as an average value from the thermal expansion at 100 to 200 ° C. during the second temperature increase.

(Warpage measurement)
In the measurement of warpage, a sample obtained by cutting a flexible printed wiring board material prepared by the following means into a 35 × 35 mm square was measured using a height gauge in a temperature and humidity environment described in the following examples and comparative examples. The lifting heights at four corners were measured, and the average value of the lifting heights was taken as the amount of warpage.

(Hygroscopic expansion coefficient)
The hygroscopic expansion coefficient is measured using a TMA with a water vapor system manufactured by Rigaku Corporation. The sample size is 5 mm wide, 15 mm long, and the load is 5 g. The humidity was changed to 40 to 70% RH, and the film was calculated from the amount of film expansion associated therewith.

(Dimension change rate)
The rate of dimensional change due to water absorption of the film is determined by using a TMA device with a water vapor system, with the sample size: 5 mm wide, 15 mm long, and 5 g of load. The calculation was performed by obtaining the time required for the expansion of the film by TMA to reach the stable region when changing from 40% RH to 70% RH.

(Reference example)
A production example of a polyimide film used in the present invention and a production method of a flexible printed wiring board material sample for warpage measurement are illustrated below. In the present invention, the following abbreviations represent the monomers shown below.
ODA: 4,4'-oxydianiline BAPP: 2,2-bis (4-aminophenoxyphenyl) propane PDA: paraphenylenediamine PMDA: pyromellitic dianhydride BTDA: 3,3 ', 4,4'- Benzophenone tetracarboxylic dianhydride

  A 15% by weight dimethylformamide (hereinafter also referred to as DMF) solution of polyamic acid obtained by synthesizing ODA / BAPP / PDA / PMDA / BTDA in a molar ratio of 25/25/50/60/40 was synthesized. A curing agent in which isoquinoline / acetic anhydride / DMF was mixed at a ratio of 4.93 g / 15.58 g / 19.49 g was rapidly stirred and mixed at a ratio of 40 g with respect to 100 g of the polyamic acid, followed by centrifugal defoaming. The mixing / defoaming step was performed at 0 ° C. The polyamic acid solution mixed with this curing agent was cast on an aluminum foil kept at room temperature using a comma coater. Hot air blown from the nozzle at 90 ° C. and 10 m / min was blown vertically onto the coating film on the aluminum foil and the back side of the aluminum foil and dried for 10 minutes to obtain a gel film having self-supporting properties, which was peeled off. (Residual volatile component amount 55% by weight). Next, this gel film was fixed to a 40 × 40 cm metal frame with four sides fixed, dried and imidized under conditions of 250 ° C. × 2 minutes, 350 ° C. × 2 minutes, 450 ° C. × 2 minutes, and a 35 μm thick polyimide film Got.

  At this time, the elastic modulus of the polyimide film is 6.5 GPa, the average linear expansion coefficient at 100 to 200 ° C. is 12 ppm / ° C., and the hygroscopic expansion coefficient with a humidity change of 40 to 70% RH at 50 ° C. is 10 ppm /% RH, The dimensional change rate when measuring the hygroscopic expansion coefficient was 30 minutes.

  An alloy of Ni / Cr (weight ratio 80/20) was formed with a thickness of 300 mm on the obtained polyimide film by sputtering to form a metalized polyimide film having a seed layer. After forming Cu with a thickness of 1000 mm on the metallized polyimide film by sputtering, the thickness of the conductor layer was increased to 8 μm in a copper sulfate high-throw plating bath, and the sample after the thickness increase was completed. The strain accumulated during plating was removed by drying at 150 ° C. for 2 hours. The finally obtained metallized polyimide film was cut into a size of 35 mm × 35 mm, and a warp measurement sample was obtained.

Example 1
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is 1 N / cm, and the time until the copper sulfate high-throw plating treatment is 1 μm in thickness is 1 minute. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, it was a warp with the conductor layer inside, and the warp amount was 8 mm.

(Example 2)
In the preparation of the warp measurement sample, the conveyance tension while the conductor layer is formed by the wet plating method is set to 1 N / cm, and the time until the copper sulfate high-throw plating process is 1 μm in thickness is set to 2 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 40 ° C. and a humidity of 60% RH, it was a warp with the conductor layer inside, and the warp amount was 6 mm.

(Example 3)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 1 N / cm, and the time until the copper sulfate high-throw plating process reaches a thickness of 1 μm is set to 3 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 20 ° C. and a humidity of 40% RH, it was a warp with the conductor layer inside, and the warp amount was 9 mm.

Example 4
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 1 N / cm, and the time until the copper sulfate high-throw plating process reaches a thickness of 1 μm is set to 3 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, it was a warp with the conductor layer inside, and the warp amount was 3 mm.

(Example 5)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 1 N / cm, and the time until the copper sulfate high-throw plating process reaches a thickness of 1 μm is set to 5 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, it was a warp with the conductor layer inside, and the warp amount was 1 mm.

(Comparative Example 1)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 1 N / cm, and the time until the copper sulfate high-throw plating treatment reaches a thickness of 1 μm is set to 10 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warp of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, the warp behavior with the conductor layer on the outside was shown.

(Comparative Example 2)
In the preparation of the warp measurement sample, the conveyance tension while the conductor layer is formed by the wet plating method is set to 1 N / cm, and the time until the copper sulfate high-throw plating process is 1 μm in thickness is 30 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warp of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, the warp behavior with the conductor layer on the outside was shown.

(Example 6)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 5 N / cm, and the time until the copper sulfate high-throw plating treatment is 1 μm in thickness is set to 5 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, it was a warp with the conductor layer inside, and the warp amount was 8 mm.

(Example 7)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 5 N / cm, and the time until the copper sulfate high-throw plating treatment is 1 μm in thickness is set to 5 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 40 ° C. and a humidity of 60% RH, it was a warp with the conductor layer inside, and the warp amount was 6 mm.

(Example 8)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 8 N / cm, and the time until the copper sulfate high-throw plating process is 1 μm in thickness is set to 5 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warpage of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, it was a warp with the conductor layer inside, and the warp amount was 3 mm.

(Comparative Example 3)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is set to 10 N / cm, and the time until the copper sulfate high-throw plating treatment is 1 μm in thickness is set to 5 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warp of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, the warp behavior with the conductor layer on the outside was shown.

(Comparative Example 4)
In the preparation of the warp measurement sample, the transport tension during the formation of the conductor layer by the wet plating method is 12 N / cm, and the time until the copper sulfate high-throw plating process is 1 μm in thickness is 5 minutes. However, the thickness was increased until the thickness of the conductor layer reached 8 μm. When the warp of this sample was measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH, the warp behavior with the conductor layer on the outside was shown.

(Comparative Example 5)
A 17% by weight DMF solution of polyamic acid was synthesized by changing the composition of the polyimide described above by changing the molar ratio of ODA / PMDA to 100/100. Using this polyamic acid, a polyimide film was produced by the method described above. At this time, the elastic modulus of the polyimide film is 3.2 GPa, the average linear expansion coefficient at 100 to 200 ° C. is 32 ppm / ° C., and the hygroscopic expansion coefficient with a humidity change of 40 to 70% RH at 50 ° C. is 30 ppm /% RH, The dimensional change rate when measuring the hygroscopic expansion coefficient was 120 minutes. Using this polyimide film, a warp measurement sample was produced by the method of Example 1 and showed a warping behavior with the conductor layer on the outside.

(Comparative Example 6)
Using the polyimide film of Comparative Example 5 to produce a warp measurement sample by the method of Example 4, the warp behavior with the conductor layer on the outside was shown.

(Pass / fail judgment of warpage evaluation results)
In the warpage evaluation result, the warp direction with the conductor layer on the inner side was shown, and when the amount of warpage was 10 mm or less, it was determined as ◯. In addition, when the warping behavior was shown with the conductor layer outside, or when the conductor layer showed the warping behavior inside, the warping amount exceeded 10 mm, it was judged as x.

  From Table 1, it can be seen that the time until the thickness of the conductor layer formed in the step (2) exceeds 1 μm and the conveyance tension affect the warping direction of the obtained flexible printed wiring board material.

  The obtained flexible printed wiring board material is used as a film carrier tape such as a flexible printed wiring board (FPC), a tape automated bonding (TAB) tape, and a COF tape. In particular, when placed in an environment of a temperature of 40 ° C. or less and a humidity of 60% RH or less, the warp is made with the conductor layer side inside, so that a flexible printed wiring board material suitable for COF tape can be obtained.

Claims (6)

Using a polyimide film showing a linear expansion coefficient smaller than the linear expansion coefficient of the conductor layer to be formed,
(1) A step of forming a metal seed layer on a polyimide film by a dry plating method,
(2) A step of forming a conductor layer by a wet plating method on the metal seed layer obtained in the step (1),
In the method for producing a flexible printed wiring board material containing
In the step (2), the time until the thickness of the formed conductor layer exceeds 1 μm is within 5 minutes, and the transport tension is 8 N / cm or less, The method for producing a flexible printed wiring board material .   2. The method for producing a flexible printed wiring board material according to claim 1, wherein in the step (2), the time until the thickness of the formed conductor layer exceeds 1 μm is 2.5 minutes or less.   The polyimide film comprises pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, paraphenylenediamine, 4,4′-oxydianiline, 2,2-bis (4 -Aminophenoxyphenyl) propane is an essential component, the elastic modulus is 5 to 10 GPa, the average linear expansion coefficient at 100 to 200 ° C. is 5 to 15 ppm / ° C., and 40% RH to 70% RH at a temperature of 50 ° C. The coefficient of dimensional change when the humidity is changed from 40% RH to 70% RH at a temperature within 50 minutes at a temperature of 50 ° C. is 5 to 15 ppm /% RH. It is within 30 minutes, The manufacturing method of the flexible printed wiring board material of Claim 1 or 2 characterized by the above-mentioned.   The metal seed layer formed on the polyimide film in the step (1) contains at least one selected from Ni, Cu, Mo, Ta, Ti, V, Cr, Fe, Co, Al, Sn, and (2) The method for producing a flexible printed wiring board material according to any one of claims 1 to 3, wherein the conductor layer formed by the wet plating method in the step is Cu.   The flexible printed wiring board material manufactured by the method according to any one of claims 1 to 4, wherein a warp amount of a sample obtained by cutting the wiring board material into a size of 35 x 35 mm has a temperature of 20 to A flexible printed circuit board material having a conductor layer of 10 mm or less in an environment of 40 ° C. and humidity of 40 to 60% RH.   The film carrier tape for chip-on-films using the flexible printed wiring board material manufactured by the manufacturing method of any one of Claims 1 thru | or 4.