JP2008040273A - Photosensitive polyimide-silicone composition, protective film and flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive polyimide-silicone composition capable of forming a protective film that is less liable to deterioration, even in a gold plating process and having satisfactory adhesive power to copper foil, a protective film of a flexible printed wiring board formed from the photosensitive polyimide-silicone composition, and a flexible printed wiring board that has the protective film. <P>SOLUTION: The photosensitive polyimide-silicone composition contains soluble polyimide resin and a positive-type photosensitizing agent, wherein the soluble polyimide resin is a condensate of aromatic tetracarboxylic acid dianhydride and diamine, the diamine containing a siliconediamine and hexafluoro-2,2-bis(3-amino-4-hydroxyphenyl)propane in the amount of 1-50 mol%, based on the total diamine. There are also provided the protective film of a flexible printed wiring board, formed from the photosensitive polyimide-silicone composition and the flexible printed wiring board that has the protective film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photosensitive polyimide silicone composition suitably used for forming a protective film of a flexible printed wiring board. The present invention further relates to a protective film formed of the photosensitive polyimide silicone composition and functioning as a cover lay of a flexible printed wiring board, and a flexible printed wiring board provided with the protective film.

  In many cases, a flexible printed wiring board (hereinafter referred to as FPC) is provided with a protective film (coverlay) for protecting wiring on the outer surface thereof. The protective film covers the wiring, the element portion, and the like, but it is necessary to expose the pad portion, the connection portion, and the like. Therefore, in forming this protective film, first, a photosensitive resin composition is applied to the entire surface or a part of the FPC substrate on which wirings, elements, etc. are formed to form a coating film, and then a predetermined portion is passed through a mask or the like. Only a method of exposing and developing and patterning to remove a part of the film is employed.

  In such a method, a positive photosensitive resin composition comprising a resin soluble in a solvent (soluble resin) and a positive photosensitive agent is widely used. In recent years, since a more flexible protective film having excellent heat resistance is desired, use of a soluble polyimide resin having excellent heat resistance has been proposed as a soluble resin.

  The soluble polyimide resin is a polyimide resin that is inherently insoluble in a solvent and is provided with solubility. And, in order to impart solubility, a method has been proposed in which a diamine component having a hydroxyl group is included in a diamine component for synthesizing a polyimide resin, and a soluble polyimide resin synthesized using a diamine having a hydroxyl group is It is proposed in Japanese Patent No. 2935994 (Patent Document 1), Japanese Patent Laid-Open No. 10-2224017 (Patent Document 2), and the like.

As a soluble polyimide resin, WO99 / 19771 (patent document) is disclosed in order to improve the flame retardance of the protective film and the adhesion to copper constituting the wiring, and to improve the flexibility and prevent problems such as warpage. A polyimide resin containing a silicone diamine in a diamine component and a photosensitive polyimide silicone composition containing the polyimide resin as described in 3) and the like are widely used.
Japanese Patent No. 2935994 Japanese Patent Laid-Open No. 10-2224017 WO99 / 19771 publication

  In the production of the photosensitive polyimide silicone composition, a diamine having a phenolic hydroxyl group is used in order to impart solubility to the constituent polyimide resin. Examples of the diamine having a phenolic hydroxyl group include 3,3′-diamino-4,4′dihydroxydiphenylsulfone (hereinafter referred to as “ABPS”) represented by the following structural formula (I), and the like.

次に示される化合物を挙げることができる。

The compound shown next can be mentioned.

However, when an FPC protective film is formed using a photosensitive polyimide silicone composition produced using these diamine components, this protective film has the following problems.
1. In manufacturing an FPC, gold plating may be necessary for forming a connection portion or the like, but this protective film is likely to deteriorate in the gold plating process. Specifically, the unexposed portion is likely to deteriorate during development, leading to whitening of the surface, and this portion is deteriorated by the plating pretreatment liquid or the plating liquid. This phenomenon occurs in both electrolytic gold plating and electroless gold plating, but the deterioration is particularly great in the electroless gold plating process.
2. Further, since this protective film has insufficient adhesive force with the copper foil constituting the FPC, there is a possibility that a developer or a plating solution may permeate from the opening and cause deterioration of the film.

  The present invention is capable of forming a protective film that is not easily deteriorated in the gold plating process and has a sufficient adhesive force to the copper foil, maintains the developability similar to that of the conventional photosensitive polyimide silicone composition, and warps. It is an object of the present invention to provide a photosensitive polyimide silicone composition that hardly causes the above problem.

  The present invention further includes an FPC protective film which is formed from this photosensitive polyimide silicone composition and hardly deteriorates in the gold plating process and has a sufficient adhesion to copper foil, and a flexible print having the protective film Provide a wiring board.

  As a result of intensive studies, the present inventor used 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (hereinafter referred to as 6FAP) as a diamine having a hydroxyl group for imparting solubility. It has been found that the above-mentioned problems can be solved by setting the copolymerization ratio of 6FAP to a predetermined range, and the present invention has been completed.

The present invention, as claim 1 thereof,
A photosensitive resin composition containing a soluble polyimide resin and a positive photosensitive agent,
The soluble polyimide resin is a condensate of aromatic tetracarboxylic dianhydride and diamine,
The diamine contains silicone diamine and hexafluoro-2,2-bis (3-amino-4-hydroxyphenyl) propane;
Provided is a photosensitive polyimide silicone composition characterized in that the content of hexafluoro-2,2-bis (3-amino-4-hydroxyphenyl) propane is 1 to 50 mol% based on the total diamine. .

  The condensate of aromatic tetracarboxylic dianhydride and diamine means a condensate obtained by reacting aromatic tetracarboxylic dianhydride and diamine in an equimolar amount of about 1: 1.

  6FAP is represented by the following structural formula (II).

  The copolymerization ratio of 6FAP is 1 to 50 mol% with respect to the total diamine. The smaller the copolymerization ratio of 6FAP, the lower the developability when forming the protective film using the obtained photosensitive polyimide silicone composition, and a thick alkaline solution or organic solvent is required. When it exceeds 50 mol%, the heat resistance of a film formed by applying the composition to a substrate or the like and curing it (hereinafter sometimes simply referred to as a film) is lowered, and the plating resistance of the film is reduced. Is greatly reduced. From the viewpoint of plating resistance, it is more preferably 50 mol% or less.

  Silicone diamine is a compound having a siloxane group in the skeleton and two primary amino groups at its ends, and for example, those represented by the following structural formula (III) are widely used.

式中、ａは１〜１００００程度の数を表す。上記の他に、下記構造式で表されるものも例示される。

In the formula, a represents a number of about 1 to 10,000. In addition to the above, those represented by the following structural formulas are also exemplified.

式中、ａ＋ｂ（式がｂを含まない場合はａ）は１〜１００００程度の数を表す。

In the formula, a + b (a when the formula does not include b) represents a number of about 1 to 10,000.

  The content of the silicone diamine is preferably 5 to 60 mol% with respect to the total diamine (claim 2). In particular, when the molecular weight of the silicone diamine is about 500 to 1,000, it is preferably 10 to 60 mol% with respect to the total diamine. When it exceeds 60 mol%, the glass transition temperature of the film is lowered and the heat resistance is lowered, whereas when it is less than 5 mol%, the warpage of the film is increased. More preferably, it is the range of 30-50 mol%. However, heat resistance and film warpage are also affected by the structure and content of other diamines.

  Specifically, as the silicone diamine, BY16-853U, BY16-853C manufactured by Toray Dow Corning Silicone, X-22-1660B-3, KF-8010, X-22-161A, X- manufactured by Shin-Etsu Chemical Co., Ltd. 22-161B or the like.

  The weight average molecular weight of the silicone diamine is preferably 1000 or less. (Claim 3). At this time, a in the formula (III) is about 8 to 9 or less. If the weight average molecular weight exceeds 1000, the adhesive strength with a copper foil or the like is lowered, which is not preferable. Here, the weight average molecular weight is a value measured by GPC and obtained by calculation using standard polystyrene (TSK standard polystyrene).

  The diamine that can be used for the production of the photosensitive polyimide silicone composition of the present invention includes 6FAP and the above-mentioned silicone diamine, but further includes other diamines within the scope of the present invention.

  Examples of other diamines include bis (3-aminopropyl) ether ethane, 3,3′-diamino-4,4′dihydroxydiphenylsulfone, 4,4′diamino-3,3′dihydroxybiphenyl, 2,2 -Bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, siloxane diamine, bis (3-aminopropyl) ether ethane, N, N-bis (3-aminopropyl) ether, 1,4-bis (3 -Aminopropyl) piperazine, isophoronediamine, 1,3'-bis (aminomethyl) cyclohexane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-methylenebis (cyclohexylamine), 4, 4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, , 3′-diaminodiphenyl ether, 4,4′-diamino-diphenyl sulfone, 3,4′-diamino-diphenyl sulfone, 3,3′-diamino-diphenyl sulfone, 2,4′-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4- Aminophenoxy) phenyl] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 4,4′bis (4-aminophenoxy) biphenyl, 1,4-bis (4-aminophenoxy) benzene, 4,4'-diaminodiphenyl sulfide 3,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 3,3′diamino-4,4′dihydroxydiphenyl sulfone, 2,4-diaminotoluene, 2,5-diaminotoluene, 3,5- Diaminobenzoic acid, 2,6-diaminopyridine, 4,4′diamino-3,3′dimethoxybiphenyl, 4,4′diamino-3,3′dimethylbiphenyl, 9,9′-bis (4-aminophenyl) fluorene Etc.

  Among these, 1,3-bis (3-aminophenoxy) benzene (hereinafter referred to as “1,3-APB”) represented by the following structural formula (IV) is preferable from the viewpoint of transparency and flexibility. used.

  Further, bis [4- (3-aminophenoxy) phenyl] sulfone (hereinafter referred to as “BAPSM”) and 1,4-bis (3-aminophenoxy) benzene (hereinafter referred to as “1,4-APB”) Also preferred). Furthermore, 1,3-bis (4-aminophenoxy) benzene, a diamine represented by the following structural formula, or the like can also be used.

  As aromatic tetracarboxylic dianhydride constituting photosensitive polyimide silicone, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid Dianhydride, 4,4′-oxydiphthalic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, bicyclo (2,2,2) -oct-7-ene-2 , 3,5,6-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, pyromellitic dianhydride, 2,2-bis (3,4-dicarboxylicoxyphenyl) ) Hexafluoropropane dianhydride, 5- (2,5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride and the like.

  Among these, 4,4'-oxydiphthalic dianhydride (hereinafter referred to as "OPDA") represented by the following formula (V) is preferable from the viewpoint of transparency and flexibility (claim 4).

  The soluble polyimide resin constituting the photosensitive polyimide silicone composition of the present invention is prepared by dissolving such aromatic tetracarboxylic dianhydride, the above-mentioned silicone diamine, 6FAP and other diamines in a solvent and heating. It can be produced by a condensation reaction. It is preferable to use the same solvent as the solvent for the photosensitive polyimide silicone composition as the solvent because a solvent replacement operation is not necessary in the production of the photosensitive polyimide silicone composition. Accordingly, examples of the solvent include those described later as the solvent for the photosensitive polyimide silicone composition.

  The soluble polyimide resin (polyimide silicone) that is the base polymer of the photosensitive polyimide silicone composition of the present invention is preferably one having a weight average molecular weight in the range of 20000 to 50000 and a molecular weight distribution of one peak distribution. (Claim 5). By using a soluble polyimide resin having such an average molecular weight and molecular weight distribution as a base polymer, it becomes difficult to produce a development residue during development, and the heat resistance, solvent resistance, and insulation film pattern obtained from this composition An insulating film pattern that has excellent mechanical strength and easily satisfies the required characteristics can be obtained. In particular, when the molecular weight distribution is a single-peak distribution and the dispersion is small, the effects of being less likely to be left undeveloped, excellent heat resistance, solvent resistance, and mechanical strength are remarkable. Here, the single-peak distribution means that the molecular weight distribution curve has substantially one peak.

  The photosensitive polyimide silicone composition of this invention contains a positive photosensitive agent with the said soluble polyimide resin. Preferred examples of the positive photosensitive agent include naphthoquinone diazide sulfonyl esters of aromatic polyhydroxy compounds. (Claim 6)

  Aromatic polyhydroxy compounds include 2,3,4-trihydroxybenzophenone, 2,3,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxy. Examples include benzophenone and novolac resin.

  Examples of naphthoquinone diazide sulfonyl compounds that form esters with aromatic polyhydroxy compounds include 1,2-naphthoquinone-2-diazide-5-sulfonic acid, 1,2-naphthoquinone-2-diazide-4-sulfonic acid, and the like. .

  Although it is necessary to adjust the amount of the positive photosensitive agent depending on the film thickness of the coating film, the type of the photosensitive agent, and the like, it is preferable to add 5 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin. If the amount is less than 5 parts by weight, sufficient sensitivity may not be obtained and a residue may be generated. If the amount exceeds 30 parts by weight, the heat resistance and solvent resistance of the resin film formed by curing of the composition will be reduced. There is a case. More preferred is 10 to 20 parts by weight.

  The photosensitive polyimide silicone composition of the present invention can be obtained by mixing the soluble polyimide resin and the positive photosensitive agent in a solvent. As the solvent, an aprotic polar solvent is preferable, and N-methyl-2-pyrrolidone, N, N′-dimethylacetamide, dimethylformamide, dimethylsulfoxide, acetonitrile, diglyme, γ-butyrolactone, γ-valerolactone, phenol, toluene , Dioxane, tetrahydrofuran, sulfolane, hexamethylphosphoramide and the like. Among these, γ-butyrolactone is preferably used from the viewpoint of high volatility, odor and the like. The amount used is preferably 1 to 20 times (weight ratio) of the soluble polyimide resin.

  The thus obtained photosensitive polyimide silicone composition of the present invention is used for the formation of FPC protective films, etc. In this case, it has developability comparable to that of conventional photosensitive polyimide silicone compositions. In addition, problems such as warpage are unlikely to occur.

  The present invention further provides a protective film (Claim 7), which is a protective film for covering the wiring of the FPC and is made of a cured product of the photosensitive polyimide silicone composition.

  The present invention further provides a flexible printed wiring board having the protective film (Claim 8).

  This protective film is provided on the outer surface of the FPC and covers them in order to protect the wiring, the element portion, and the like. On the other hand, since it is necessary to expose the connection part and the pad part, first, the photosensitive polyimide silicone composition is applied to the entire surface of the FPC, and if necessary, the solvent is removed by heating (prebaking) to form a coating film. After that, a pattern is formed through an exposure process of irradiating an actinic ray such as ultraviolet rays through a mask, etc., and a development process of developing with an alkaline developer, and a method of removing the coating film on the exposed part is provided. It is done.

  Examples of the alkali developer include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and the like. Since the surface of the coating film becomes hydrophobic and may not be compatible with the developer at the time of development, a solvent such as N-methylpyrrolidone, alcohols or a surfactant may be added to the developer.

  In many cases, the soluble polyimide resin used in the present invention has already been imidized at the stage of synthesis. Therefore, heating for forming an imide ring is not necessary, and a heat treatment step may be performed as necessary after pattern formation. This is performed to evaporate residual solvent contained in the pattern. Therefore, heating at a high temperature necessary for forming an imide ring is unnecessary.

  Since the protective film thus obtained is formed from the photosensitive polyimide silicone composition, it is not easily deteriorated even in the gold plating process and has a sufficient adhesive force to the copper foil. .

  By using the photosensitive polyimide silicone composition of the present invention, it is possible to form an FPC protective film that is not easily deteriorated in the gold plating process and has sufficient adhesion to the copper foil. Further, even in the process of forming the protective film of this FPC, the same developability as that of the conventional photosensitive polyimide silicone composition is exhibited, and the warp and the like are small.

  The protective film of the present invention is hardly deteriorated even in the gold plating process and has a sufficient adhesive force to the copper foil.

  Next, the best mode for carrying out the present invention will be described below with reference to examples, but the present invention is not limited to these examples.

(Example 1)
(Synthesis of soluble polyimide resin)
1. In a 1 L separate flask equipped with a condenser, a mechanical stirrer, and a nitrogen introduction tube, in a nitrogen atmosphere, 140 g of γ-butyrolactone as a solvent was added to silicone diamine (KF8010 manufactured by Shin-Etsu Silicone, molecular weight: 830, amine). Equivalent: 415) 33.20 g (0.04 mol) is added and dissolved. Further, 2.0 g of pyridine as a catalyst and 100 g of toluene as an azeotropic solvent are added.

2. As an acid dianhydride, 37.22 g (0.12 mol) of OPDA (molecular weight: 310.2) was gradually added, and the whole amount was added, stirred for 15 minutes, and then heated to 160 ° C. with a mantle heater and reacted for 1 hour. Let During this time, the cooling water is poured and toluene is circulated. Thereafter, the heating is stopped and the mixture is naturally cooled to around room temperature (50 ° C. or lower).

3. Next, as a diamine, 1,3-APB (molecular weight: 292.3) 20.46 g (0.07 mol) and 6FAP (molecular weight: 366) 3.66 g (0.01 mol) were added, and about 32% Add 51 g of solvent γ-butyrolactone so as to have a solid content. The mixture is stirred for 15 minutes, and then heated to 160 ° C. in an oil bath and reacted for 3 hours to obtain a reaction solution. Thereafter, the pressure was reduced and toluene and pyridine were removed from the reaction solution to obtain a varnish.

  The varnish thus obtained was subjected to the following measurements. The results are shown in Table 2.

(Molecular weight measurement)
The dispersity (Mw / Mn), which is the ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn), of the obtained varnish was measured by GPC (manufactured by Tosoh Corporation, HLC-8220 GPC). As the carrier solvent, a solution obtained by dissolving LiBr at a concentration of 0.1 N in NMP was used. The molecular weight is a converted value calculated using standard polystyrene (TSK standard polystyrene).

(Glass transition temperature measurement)
Using a dynamic viscoelasticity measuring apparatus (Seiko Instruments, DMS6100), tan δ was measured in an air atmosphere at a heating rate of 10 ° C./min, and the temperature at the maximum value of tan δ was defined as the glass transition temperature (Tg). .

(Thermogravimetric analysis)
Using a TG-DTA (simultaneous differential heat / thermogravimetric measuring device: TG / DTA220, manufactured by Seiko Instruments Inc.), the temperature (Td5) at which the weight is reduced by 5% is measured at a heating rate of 10 ° C./min in an air atmosphere. did.

(Warpage measurement)
The varnish obtained on a 18 μm thick copper foil was applied and dried to form a 20 μm thick film, and then this composite material was cut into 100 mm squares and placed on a horizontal surface. The height of the warp was measured and the average was obtained.

(Evaluation of photosensitive developability)
To the obtained varnish, 15 phr of 1,2-naphthoquinone-2-diazide-5-sulfonic acid ester (manufactured by Toyo Gosei Co., Ltd., hereinafter referred to as PC5) was added and mixed as a photosensitive agent, and a photosensitive polyimide silicone composition ( Photosensitive ink) was prepared. The photosensitive ink was applied by screen printing onto a 18 μm thick copper foil and then prebaked to obtain a 12 to 15 μm thick film. This film was exposed to 800 mJ / cm ^{2 of} ultraviolet rays through a predetermined mask.

  Development was performed at room temperature for 7 minutes using a developer, rinsed with pure water, and then dried. Three types of developers were used: (a) 3% NaOH + 3% ethanolamine, (b) 3% NaOH + 0.5% ethanolamine, and (c) 3% NaOH. The state of the dried film was visually observed and evaluated according to the following criteria. The results are shown in Table 2.

A: Clear patterning is possible up to L / S of 50 μm or less, and no deterioration of the film or penetration into the interface is observed.
○: Patterning is possible up to L / S of about 50 μm, and there is no residue. Although the film is not deteriorated, some penetration into the interface may be observed.
(Triangle | delta): Although it has patterned mostly, a residue is seen in an exposure part or deterioration of a film | membrane is seen.
X: Patterning is not possible or deterioration is remarkable.

Examples 2-9, Comparative Examples 1-9
Based on the formulation shown in Table 1, the varnishes of Examples 2 to 9 and Comparative Examples 1 to 9 were obtained in the same manner as Example 1, and the same measurements as those of Example 1 were performed. The results are also shown in Table 2. In Table 1, SiOn represents silicone diamine, the molar ratio is the molar ratio of each component in the diamine, and the mol% is the molar ratio expressed in%. The total number of moles of diamine is the same as the number of moles of OPDA.

  The results in Table 2 show that when 6FAP is used (Example), warpage and glass transition temperature almost the same as those when ABPS is used (Comparative Example) can be obtained. In addition, from the result of Table 2, it turns out that curvature and glass transition temperature are greatly influenced by the quantity of silicone diamine. When the amount of silicone diamine is small, the warpage increases. However, even in the case of about 33 mol% with respect to the total diamine (Examples 1 to 3), the warpage is not significant and is in a range that can be used for applications such as a protective film. On the other hand, when the amount of silicone diamine is large, the glass transition temperature is lowered. In the case of about 67 mol% with respect to the total diamine (Examples 7 to 9), the glass transition temperature is about 45 ° C., and even in this case, it can be used for applications such as a protective film, but more excellent heat resistance. It is desired that the glass transition temperature is higher in order to obtain The results in Table 2 indicate that about 60 mol% or less is preferable with respect to the total diamine.

  The results in Table 2 show that when 6FAP is used (Example), almost the same developability is obtained as when ABPS is used (Comparative Example). However, when the amount of ABPS is large, film loss occurs and tends to deteriorate. Photosensitive developability is greatly influenced by the amount of 6FAP (OH group). Photosensitive developability greatly depends on the concentration of the developer, but when a developer having a composition close to 3% NaOH + 3% ethanolamine or 3% NaOH + 0.5% ethanolamine is used, the amount of 6FAP is based on the total diamine. It is shown that the range of 10 to 40 mol% (corresponding to Examples 2, 3, 5, 6, 8, and 9) is preferable.

(Examples 10-16, Comparative Examples 10-11)
Based on the formulation shown in Table 3, varnishes of Examples 10 to 16 and Comparative Examples 10 to 11 were obtained in the same manner as in Example 1 (as shown in Table 3, in some Examples and Comparative Examples) , APB was replaced with BAPSM, OPDA was replaced with benzophenone tetracarboxylic acid (BTDA), and 6FAP was replaced with ABPS.) In the same manner as in the evaluation of photosensitive developability in Example 1, photosensitive polyimide was used. A silicone composition (photosensitive ink) was prepared. Further, in the same manner, screen printing, pre-baking, exposure, and development (developer: 3% NaOH + 3% ethanolamine aqueous solution) of the photosensitive ink are performed, and then afterbaking (160 ° C., 30 minutes) for evaluation. FPC was obtained.

  Using the evaluation FPC, migration resistance and plating resistance were evaluated by the following methods. The results are shown in Table 4. In Table 3, SiOn represents silicone diamine, the molar ratio is the molar ratio of each component in the diamine, and the molar% is the molar ratio expressed in%. The total number of moles of diamine is the same as the number of moles of OPDA or BTDA.

(Evaluation of migration resistance)
Each of the photosensitive inks is applied on a migration evaluation double-sided plate having a copper foil patterning of 18 μm thick and dried to form an insulating film having a thickness of 12 to 15 μm, and light is transmitted through a predetermined mask. Then, development with a developer was performed to prepare an FPC for evaluation. This was placed under a high temperature and high humidity of 85 ° C. and relative humidity 85% RH, a DC voltage of 50 V was applied between the conductors for 1000 hours, the state of the resist film was observed, and evaluated according to the following criteria. The results are shown in Table 4.

○: No abnormality at all.
Δ: No abnormality was observed in the current value, but minute dendrite formation was observed.
X: No abnormality was observed in the current value, but a large dendrite formation was observed.
XX: Dendrite formation was observed on the entire surface, and an abnormality occurred in the current value.

(Evaluation of plating resistance)
Each of the photosensitive inks is coated on a copper foil having a thickness of 18 μm, dried to form a resist film having a thickness of 12 to 15 μm, irradiated with light through a predetermined mask, and then developed with a developer. After that, (a) electroless gold plating and (b) electrolytic gold plating are performed. The state after plating was observed and evaluated according to the following criteria. The results are shown in Table 4.

○: No abnormality.
Δ: Minor on the surface of the film, or slight penetration of the terminal part was observed.
X: The surface of the film was deteriorated, and the penetration of the terminal portion was observed.
XX: The film was cracked and peeled, and the insulating part was also partially plated.

The developers used in (Evaluation of migration resistance) and (Evaluation of plating resistance) are shown below.
Examples 11, 12 and 14: 3% NaOH + 3% ethanolamine Examples 10, 13, 15 and 16 and comparative examples: 3% NaOH + 0.5% ethanolamine

As shown in the results of Table 4, when 6FAP is used as the diamine component and the content is in the range of 1 to 50 mol% (Example), the migration resistance and the plating resistance are excellent. In particular, Examples 11 and 12 in which APB and OPDA are used, the content of 6FAP is 20 mol% or less and the SiOn content is 50 mol%, show excellent plating resistance even in the case of electroless gold plating. On the other hand, when ABPS is used as a diamine component (comparative example), both migration resistance and plating resistance are far inferior to those of the examples (when 6FAP is used).

Claims (8)

A photosensitive resin composition containing a soluble polyimide resin and a positive photosensitive agent,
The soluble polyimide resin is a condensate of aromatic tetracarboxylic dianhydride and diamine,
The diamine contains silicone diamine and hexafluoro-2,2-bis (3-amino-4-hydroxyphenyl) propane;
A photosensitive polyimide silicone composition, wherein the content of hexafluoro-2,2-bis (3-amino-4-hydroxyphenyl) propane is 1 to 50 mol% with respect to the total diamine.   Content of the said silicone diamine is 5-60 mol% with respect to all the diamine, The photosensitive polyimide silicone composition of Claim 1 characterized by the above-mentioned.   The weight average molecular weight of the said silicone diamine is 1000 or less, The photosensitive polyimide silicone composition of Claim 1 or Claim 2 characterized by the above-mentioned.   The photosensitive polyimide silicone composition according to any one of claims 1 to 3, wherein the aromatic tetracarboxylic dianhydride contains 4,4'-oxydiphthalic dianhydride.   The photosensitive polyimide silicone composition according to any one of claims 1 to 4, wherein the soluble polyimide resin has a weight average molecular weight of 20,000 to 50,000 and a molecular weight distribution of one peak distribution.   6. The photosensitive polyimide silicone composition according to any one of claims 1 to 5, wherein the positive photosensitive agent is a naphthoquinone diazide sulfonyl ester of an aromatic polyhydroxy compound.   A protective film for covering the wiring of a flexible printed wiring board, comprising a cured product of the photosensitive polyimide silicone composition according to any one of claims 1 to 6. A flexible printed wiring board comprising the protective film according to claim 7.