CN116847983A

CN116847983A - Laminated structure and flexible printed circuit board

Info

Publication number: CN116847983A
Application number: CN202280012926.5A
Authority: CN
Inventors: 高岛脩平; 小田桐悠斗; 米田一善; 花田忠彦
Original assignee: Taiyo Holdings Co Ltd
Current assignee: Taiyo Holdings Co Ltd
Priority date: 2021-02-26
Filing date: 2022-02-25
Publication date: 2023-10-03
Also published as: WO2022181764A1; JPWO2022181764A1; KR20230151977A

Abstract

[ problem ] to provide: a laminated structure and a dry film thereof, which can form a photosensitive structure excellent in metal adhesion to a permanent insulating film, warpage resistance and bending resistance. [ solution ] A laminated structure is characterized by comprising: and a resin layer (B) laminated on the resin layer (A), wherein the resin layer (B) is a photosensitive thermosetting resin composition containing 1 or more components selected from the group consisting of polyimide, polyamideimide and polyamide, the elastic modulus of the cured product of the resin layer (A) when measured at 23 ℃ is 0.3GPa to 1.5GPa, the elastic modulus of the cured product of the resin layer (B) when measured at 23 ℃ is greater than 1.5GPa to 3.5GPa, and the film thickness of the resin layer (A) is greater than the film thickness of the resin layer (B).

Description

Laminated structure and flexible printed circuit board

Technical Field

The present invention relates to a laminated structure, a dry film, and a flexible printed circuit board, which are useful for forming an insulating film of the flexible printed circuit board.

Background

With the demand for miniaturization and thinning of electronic products, flexible printed circuit boards (FPCs) that can be folded and housed have been in high demand. The FPC functions as a flexible cable excellent in flexibility based on the basic structure of the conductor such as a base film and a copper foil, and the cover layer, and contributes to an improvement in the degree of freedom in connection between substrates.

The cover layer is a protective material for improving insulation reliability of the FPC, and can be roughly divided into: a non-photosensitive cover layer formed into a predetermined shape by a mold or the like and bonded to the FPC after the circuit formation; and a photosensitive cover layer which is subjected to micromachining by photolithography.

The alignment accuracy of the opening portion of the non-photosensitive cover layer is poor, and an expensive die is required for each punched pattern, and therefore, the productivity is poor.

On the other hand, as the wiring density of FPCs increases, the use of photosensitive coverlays has been increasing because they can cope with fine patterns.

Further, as a method of increasing the information amount of the unit FPC, a method of manufacturing a multi-layer FPC is considered. In general, there is a method of laminating a flexible copper-clad laminate in which a circuit is formed by a subtractive method with a flexible adhesive such as a bonding sheet to accommodate an interlayer insulating material, a cover layer, and a solder resist layer (patent document 1 and patent document 2).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2013-76833

Patent document 2: japanese patent laid-open No. 2004-157419

Disclosure of Invention

Problems to be solved by the invention

However, in recent years, in order to further improve the wiring density, the application of the half-additive method has been gradually increased from the conventional subtractive method as a circuit forming method of FPC. In the semi-additive method, a finer wiring can be drawn than in the subtractive method, and the contact area between copper and the substrate is reduced, so that adhesion to a conductor layer such as Cu, ti, ni, cr is required more than in the conventional method for the permanent insulating film.

In the technique described in patent document 1, as an interlayer electrical insulating material for a multilayer printed circuit board, there is a concern that adhesion to a conductor layer is low in a half-additive method and wiring is broken due to bending at the time of mounting, and high reliability required for FPC of the next generation cannot be satisfied.

On the other hand, in the technique described in patent document 2, a flexible resin skeleton having flexibility is used as an insulator used in the outermost layer, but the warp suppressing effect after curing is insufficient, and the substrate produced by heat shrinkage generated during curing is warped, and there is a concern that the yield of the component is lowered.

Accordingly, an object of the present invention is to provide: a laminated structure capable of forming a photosensitive structure excellent in metal adhesion to a permanent insulating film, warpage resistance and bending resistance, and a dry film thereof, and further, a laminated structure comprising: a printed wiring board having the cured product as a protective film, such as a coverlay, a solder resist, or an interlayer insulating material.

Solution for solving the problem

In view of the above problems, the present inventors have conducted intensive studies to obtain a photosensitive resin composition excellent in both metal adhesion and warpage resistance and bending resistance of a dry film, and as a result, have found that: polyimide-based resins have an excellent effect of improving metal adhesion. However, in the case of the polyimide resin layer 1 layer structure, it is difficult to obtain sufficient warpage resistance and bending resistance.

Accordingly, the present inventors have further studied intensively, and as a result, have conceived a 2-layer structure in which a resin layer of polyimide resin excellent in metal adhesion is laminated with a resin layer for relaxing stress applied to a substrate in order to improve bending resistance, and have found that an appropriate elastic modulus between the resin layers is obtained, whereby warpage resistance and bending resistance can be improved, and the above problems can be solved, and have completed the present invention.

That is, the above-described problems of the present invention are solved by a laminated structure comprising:

the laminated structure is characterized by comprising: a resin layer (A) formed from an alkali-developable resin composition, and a resin layer (B) laminated on the resin layer (A),

the resin layer (B) is a photosensitive thermosetting resin composition containing 1 or more components selected from the group consisting of polyimide, polyamideimide and polyamide,

the elastic modulus of the cured product of the resin layer (A) is 0.3GPa to 1.5GPa at 23 ℃, the elastic modulus of the cured product of the resin layer (B) is more than 1.5GPa to 3.5GPa at 23 ℃,

and the film thickness of the resin layer (A) is larger than that of the resin layer (B).

The cured product of the present invention is obtained by subjecting a resin composition or a laminated structure constituting the resin layer (a) and the resin layer (B) to, for example, a lamination step, an exposure step, a development step, and a heat curing (post-curing) step, and curing the resin composition or the laminated structure. The heating temperature in the heat curing (post-curing) step is, for example, 140 to 180℃and the heating time is, for example, 20 to 120 minutes.

The present invention also relates to a cured product obtained from the laminated structure.

A preferable cured product of the present invention is characterized in that, in a 90 DEG peeling test of the seed layer of a laminate formed of the cured product and a seed layer, the seed layer is laminated on a substrate such as a printed wiring board with a resin layer (A) interposed therebetween, and the seed layer is formed on the cured product by sputtering in the order of Ni layer and Cu layer, the adhesion between the seed layer and the cured product is 5.0N/cm or moreFormed by the method. The seed layer of Ni/Cu formed by the sputtering is formed as follows: at a sputtering pressure of 7.0X10 ^-1 Forming a Ni seed layer at a sputtering pressure of 7.0X10 on the Ni seed layer at 50nm under a treatment of Pa, 100W for 10 minutes ^-1 The Cu seed layer was formed at 500nm under Pa, 300W, and 15 minutes.

In addition, another aspect of the present invention relates to: the flexible printed circuit board having the cured product, the multi-layer flexible printed circuit board having a portion laminated with at least 2 layers or more of the cured product, and the dry film characterized in that at least one side of the laminated structure is supported or protected by a film.

In addition, another aspect of the present invention relates to: the flexible printed circuit board and the electronic component having the multilayer flexible printed circuit board.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there is provided: a cured product or a dry film which has higher metal adhesion and further has excellent warp resistance and bending resistance, and is used as a protective layer for electronic components. Therefore, the cured product of the present invention can be suitably used as, for example, a coverlay, a solder resist layer, or an interlayer insulating material for a flexible printed circuit board. Further, since the resin composition forming the cured product of the present invention has the above-described characteristics, the resin composition is particularly suitable for circuit formation by the half-additive method. The cured product of the present invention is formed so that the laminated structure is cured at the time of use and is relatively easily obtained, and therefore, workability is also good.

Detailed Description

The laminated structure of the present invention is basically preferably a 2-layer structure having a resin layer (a) and a resin layer (B) laminated on the resin layer (a).

The laminated structure of the present invention is laminated on a substrate such as a printed circuit board via a resin layer (A).

Examples of the substrate include a printed wiring board and a flexible printed wiring board on which a circuit is formed in advance from copper or the like, but the present invention is particularly suitable for flexible printed wiring board applications.

Here, the laminate structure of the present invention must have the desired metal adhesion, warp resistance, and bending resistance, and further have the functions inherent to the protective layer of the base material, taking into consideration various factors such as flexibility of the resin layer (a) and the resin layer (B), adhesion to each other, adhesion to the base material, or heat resistance. For this reason, the laminated structure has a 2-layer structure, and the types of components of the resin layer (a) and the resin layer (B), the elastic modulus of each cured product, and the film thickness (also referred to as layer thickness) of each cured product are set.

In the present invention, the elastic modulus and the film thickness are set so that the elastic modulus of the cured product of the resin layer (a) after curing is smaller than the elastic modulus of the resin layer (B), that is, the elastic modulus of the cured product of the resin layer (a) when measured at 23 ℃ is 0.3GPa or more and 1.5GPa or less, the elastic modulus of the cured product of the resin layer (B) when measured at 23 ℃ is greater than 1.5GPa and 3.5GPa or less, and the film thickness of the resin layer (a) in the laminated structure is greater than the film thickness of the resin layer (B).

Here, the film thickness of the resin layer (a) is preferably 5 to 200 μm, more preferably 5 to 150 μm. The film thickness of the resin layer (B) is preferably 1 to 10. Mu.m, more preferably 3 to 10. Mu.m.

The components for forming the resin layers (a) and (B) may be selected so that the modulus of elasticity and the film thickness can satisfy the desired ranges. The laminated structure of the present invention, the resin composition forming the laminated structure, and the components thereof will be described below.

[ resin layer (A) ]

The resin layer (a) is expected to not only function as an adhesive layer with a base material, but also have characteristics to cope with various circuit pattern formation. Therefore, the resin layer (a) is preferably formed of an alkali-developable resin composition containing at least 1 or more component selected from alkali-developable resins (hereinafter, also referred to as alkali-soluble resins) that can be developed in an alkali solution.

As such an alkali-developable resin composition, a photocurable resin composition or a thermosetting resin composition may be used as long as it is a composition containing an alkali-soluble resin developable in an alkali solution containing 1 or more functional groups selected from the group consisting of phenolic hydroxyl groups, mercapto groups and carboxyl groups. The resin composition preferably includes a compound having 2 or more phenolic hydroxyl groups, a carboxyl group-containing resin, a compound having a phenolic hydroxyl group and a carboxyl group, and a compound having 2 or more mercapto groups, and any known resin composition can be used. In addition, the user in the resin layer (B) may be similarly used.

Specifically, examples thereof include photocurable thermosetting resin compositions which have been conventionally used as solder resist compositions and which contain a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin, a compound having an ethylenically unsaturated bond, a photopolymerization initiator and a thermally reactive compound. In addition, a resin composition containing a carboxyl group-containing polyurethane resin, a carboxyl group-containing resin, a photobase generator, and a thermosetting component may also be used. The resin composition can be developed by adding a polyurethane resin having a carboxyl group to a thermosetting component by heating after exposure using a base generated from a photobase generator as a catalyst, and removing an unexposed portion by an alkali solution. The amount of the alkali-soluble resin to be blended is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total solid content of the resin composition constituting the resin layer (a).

As each component of the alkali-developable resin composition used for constituting the resin layer (a), a user in the resin layer (B) may be similarly used, except that a known common one may be used.

Specifically, the thermally reactive compound may be an epoxy resin, and the photoreactive compound may be a compound having an ethylenically unsaturated bond.

As the compounding amount of the heat-reactive compound, the equivalent ratio (alkali-soluble group such as carboxyl group: heat-reactive group such as epoxy group) to the alkali-soluble resin of the resin layer (a) is preferably 1:0.1 to 1:10. the above equivalent ratio is more preferably 1:0.2 to 1:5.

by setting the compounding ratio to the range, development becomes good, and a fine pattern can be easily formed.

The elastic modulus measured after leaving the cured product of the resin layer (A) at room temperature of 23℃for 24 hours is preferably in the range of 0.3Pa to 1.5GPa, more preferably in the range of 0.5GPa to 1.5 GPa. Thus, the laminated structure of the present invention has excellent bending resistance as a cured product.

Here, the elastic modulus of the cured product can be obtained by appropriately adjusting the components in the resin layer (a) to obtain a desired value. Specifically, the following tends to occur: the amount of the alkali-soluble resin having a side chain such as a polycarbonate structure incorporated therein decreases as the amount of the alkali-soluble resin blended increases, and increases as the amount of the alkali-soluble resin blended decreases. In addition, compounds having an ethylenically unsaturated bond tend to be as follows: the content of the compound having an ethylenic unsaturated bond greater than 2 functions in the 1 molecule becomes large if it increases, and becomes small if it decreases.

The amount of the compound having an ethylenically unsaturated bond in the resin layer (a) to be blended is 5 to 50 parts by mass, more preferably 5 to 40 parts by mass, based on 100 parts by mass of the alkali-soluble resin in the resin layer (a), and the amount of the epoxy resin in the resin layer (a) to be blended is 5 to 50 parts by mass, more preferably 5 to 30 parts by mass, based on 100 parts by mass of the alkali-soluble resin in the resin layer (a), so that the elastic modulus can be reduced. Here, (meth) acrylate is a term generically used for acrylate, methacrylate and a mixture thereof in the present invention, and the same applies to other similar expressions. In the present invention, the term "liquid at room temperature" means that it is liquid at 15 ℃. The determination of the liquid state is performed according to the "method of confirming liquid state" attached to page 2 of the province (province of the ministry of the peace of year, no. 1) concerning the test and the property of dangerous objects.

Thus, the elastic modulus of the desired cured product can be obtained by appropriately adjusting the blending amount of the alkali-soluble resin, the compound having an ethylenically unsaturated bond, and the epoxy resin within the above-mentioned range.

The modulus of elasticity measured after leaving the cured product of the resin layer (B) at room temperature of 23℃for 24 hours can be similarly adjusted.

[ resin layer (B) ]

The resin layer (B) mainly functions as a protective layer of a base material, and for example, a photocurable thermosetting resin composition containing a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin, a compound having an ethylenically unsaturated bond, a photopolymerization initiator, and a thermally reactive compound, or a photosensitive thermosetting resin composition containing a carboxyl group-containing resin, a photobase generator, and a thermally reactive compound, which have been conventionally used as a solder resist composition, may be used as the resin layer (B).

Among them, the resin layer (B) is preferably formed of a photosensitive thermosetting resin composition containing 1 or more components selected from the group consisting of polyimide, polyamideimide, and polyamide.

In the present invention, 1 or more components selected from the group consisting of polyimide, polyamideimide and polyamide can be obtained by introducing imide, amidimide or amide into an alkali-soluble resin such as carboxyl group or acid anhydride group according to a known and commonly used method.

Examples of the polyimide include resins obtained by reacting one or both of an amine component and an isocyanate component with a carboxylic anhydride component. Imidization may be performed by thermal imidization, chemical imidization, or a combination thereof.

Among them, those having an imide ring are more preferable.

In addition, other than polyimide, polyamide imide having an amide bond may be used, or polyamide may be used in addition.

Of these polyimide, polyamideimide and polyamide, 1 kind may be used, but 2 kinds or 3 kinds or more may be used simultaneously.

The carboxylic anhydride component includes tetracarboxylic anhydride, tricarboxylic anhydride, and the like, but is not limited to these anhydrides, and may be any compound having an acid anhydride group and a carboxyl group which react with an amino group or an isocyanate group, and may be used as long as it contains a derivative thereof. These carboxylic anhydride components may be used alone or in combination.

Examples of the tetracarboxylic acid anhydride include pyromellitic dianhydride, 3-fluoropyromellitic dianhydride, 3, 6-difluoropyromellitic dianhydride, 3, 6-bis (trifluoromethyl) pyromellitic dianhydride, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3', 4' -biphenyl tetracarboxylic dianhydride, 4' -oxydiphthalic dianhydride, 2' -difluoro-3, 3',4,4' -benzophenone tetracarboxylic dianhydride, 3',4,4' -biphenyltetracarboxylic dianhydride, 4' -oxydiphthalic dianhydride, 2' -difluoro-3, 3',4,4' -biphenyltetracarboxylic dianhydride, 5' -bis (trifluoromethyl) -3,3', 4' -biphenyltetracarboxylic dianhydride, 6' -bis (trifluoromethyl) -3,3',4,4' -biphenyltetracarboxylic dianhydride, 2', 5' -tetrakis (trifluoromethyl) -3,3', 4' -biphenyltetracarboxylic dianhydride, 2', 6' -tetrakis (trifluoromethyl) -3,3',4,4' -biphenyltetracarboxylic dianhydride, 2', 5' -tetrakis (trifluoromethyl) -3,3',4,4' -biphenyltetracarboxylic dianhydride, 2', 6' -tetrakis (trifluoromethyl) -3,3', 3,3"",4,4 '-biphenyltetracarboxylic dianhydride, methylene-4, 4' -diphthalic dianhydride, 1-ethylidene-4, 4 '-diphthalic dianhydride, 2-propylidene-4, 4' -diphthalic dianhydride, 1, 2-ethylene-4, 4 '-diphthalic dianhydride, 1, 3-trimethylene-4, 4' -diphthalic dianhydride 1, 4-tetramethylene-4, 4 '-biphthalic dianhydride, 1, 5-pentamethylene-4, 4' -biphthalic dianhydride, 2-bis (3, 4-dicarboxyphenyl) -1, 3-hexafluoropropane dianhydride, difluoromethylene-4, 4 '-biphthalic dianhydride, 1, 2-tetrafluoro-1, 2-ethylene-4, 4' -biphthalic dianhydride 1, 4-tetramethylene-4, 4 '-biphthalic dianhydride, 1, 5-pentamethylene-4, 4' -biphthalic dianhydride, 2-bis (3, 4-dicarboxyphenyl) -1, 3-hexafluoropropane dianhydride difluoromethylene-4, 4 '-biphthalic dianhydride, 1, 2-tetrafluoro-1, 2-ethylene-4, 4' -biphthalic dianhydride, 1, 4-bis (3, 4-dicarboxyphenoxy) benzene dianhydride, 1, 3-bis [ 2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, 1, 4-bis [ 2- (3, 4-dicarboxyphenyl) -2-propyl ] benzene dianhydride, bis [ 3- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride bis [ 4- (3, 4-dicarboxyphenoxy) phenyl ] methane dianhydride, 2-bis [ 3- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, 2-bis [ 4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, 2-bis [ 3- (3, 4-dicarboxyphenoxy) phenyl ] 1, 3-hexafluoropropane dianhydride 2, 2-bis [ 4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, bis (3, 4-dicarboxyphenoxy) dimethylsilane dianhydride, 1, 3-bis (3, 4-dicarboxyphenoxy) -1, 3-tetramethyldisiloxane dianhydride, 2,3,6, 7-naphthalene tetracarboxylic dianhydride, 1,2,5, 6-naphthalene tetracarboxylic dianhydride, 3,4,9, 10-pyrene tetracarboxylic dianhydride, 2,3,6, 7-anthracene tetracarboxylic dianhydride, 1,2,7, 8-phenanthrene tetracarboxylic dianhydride, 1,2,3, 4-butane tetracarboxylic dianhydride, 1,2,3, 4-cyclobutane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane-1, 2,3, 4-tetracarboxylic dianhydride, cyclohexane-1, 2,4, 5-tetracarboxylic dianhydride, 3',4,4' -dicyclohexyltetracarboxylic dianhydride, carbonyl-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, methylene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1, 2-ethylene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1, 1-ethylidene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 2-propylidene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 1, 3-hexafluoro-2, 2-propylidene-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride oxy-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, thio-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, sulfonyl-4, 4' -bis (cyclohexane-1, 2-dicarboxylic acid) dianhydride, 3' -difluoromethoxy-4, 4' -diphthalic dianhydride, 5' -difluoromethoxy-4, 4' -diphthalic dianhydride, 6' -difluoromethoxy-4, 4' -diphthalic dianhydride, 3',5,5', 6' -hexafluorooxy-4, 4' -diphthalic dianhydride, 3' -bis (trifluoromethyl) oxy-4, 4' -diphthalic dianhydride, 5' -bis (trifluoromethyl) oxy-4, 4' -diphthalic dianhydride, 6,6 '-bis (trifluoromethyl) oxy-4, 4' -diphthalic dianhydride, 3', 5' -tetrakis (trifluoromethyl) oxy-4, 4 '-diphthalic dianhydride, 3',6,6 '-tetrakis (trifluoromethyl) oxy-4, 4' -diphthalic dianhydride, 5', 6' -tetrakis (trifluoromethyl) oxy-4, 4 '-diphthalic dianhydride, 3',5,5', 6' -hexa (trifluoromethyl) oxy-4, 4 '-biphthalic dianhydride, 3' -difluorosulfonyl-4, 4 '-biphthalic dianhydride, 5' -difluorosulfonyl-4, 4 '-biphthalic dianhydride, 6' -difluorosulfonyl-4, 4 '-biphthalic dianhydride, 3',5,5', 6' -hexafluorosulfonyl-4, 4 '-diphthalic dianhydride, 3' -bis (trifluoromethyl) sulfonyl-4, 4 '-diphthalic dianhydride, 5' -bis (trifluoromethyl) sulfonyl-4, 4 '-diphthalic dianhydride, 6' -bis (trifluoromethyl) sulfonyl-4, 4 '-diphthalic dianhydride, 3',5,5 '-tetra (trifluoromethyl) sulfonyl-4, 4' -diphthalic dianhydride, 3', 6' -tetra (trifluoromethyl) sulfonyl-4, 4 '-diphthalic dianhydride, 5',6,6' -tetra (trifluoromethyl) sulfonyl-4, 4' -biphthalic dianhydride, 3', 5',6,6' -hexa (trifluoromethyl) sulfonyl-4, 4' -diphthalic dianhydride, 3' -difluoro-2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 5' -difluoro-2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 6' -difluoro-2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 3', 5',6,6' -hexafluoro-2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 3' -bis (trifluoromethyl) -2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 5' -bis (trifluoromethyl) -2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 6' -difluoro-2, 2-perfluoropropylidene-4, 4' -diphthalic dianhydride, 3',5,5' -tetrakis (trifluoromethyl) -2, 2-perfluoropropylidene-4, 4' -biphthalic dianhydride, 3', 6' -tetrakis (trifluoromethyl) -2, 2-perfluoropropylidene-4, 4' -biphthalic dianhydride, 5',6,6' -tetra (trifluoromethyl) -2, 2-perfluoropropylidene-4, 4' -biphthalic dianhydride, 3', 5',6,6 '-hexa (trifluoromethyl) -2, 2-perfluoropropylidene-4, 4' -biphthalic dianhydride, 9-phenyl-9- (trifluoromethyl) xanthene-2, 3,6, 7-tetracarboxylic dianhydride, 9-bis (trifluoromethyl) xanthene-2, 3,6, 7-tetracarboxylic dianhydride, bicyclo [ 2,2 ] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, 9-bis [ 4- (3, 4-dicarboxy) phenyl ] fluorene dianhydride, 9-bis [ 4- (2, 3-dicarboxy) phenyl ] fluorene dianhydride, ethylene glycol bis (trimellitate) dianhydride, 1,2- (ethylene) bis (trimellitate) anhydride, 1,3- (trimethylene) bis (trimellitate) anhydride 1,4- (tetramethylene) bis (trimellitic anhydride), 1,5- (pentamethylene) bis (trimellitic anhydride), 1,6- (hexamethylene) bis (trimellitic anhydride), 1,7- (heptamethylene) bis (trimellitic anhydride), 1,8- (octamethylene) bis (trimellitic anhydride), 1,9- (nonamethylene) bis (trimellitic anhydride), 1,10- (decamethylene) bis (trimellitic anhydride), 1,12- (dodecamethylene) bis (trimellitic anhydride), 1,16- (hexadecamethylene) bis (trimellitic anhydride), 1,18- (octadecyl methylene) bis (trimellitic anhydride), and the like.

Examples of the tricarboxylic acid anhydride include trimellitic anhydride and nuclear hydrogenated trimellitic anhydride.

The amine component may be a diamine such as an aliphatic diamine or an aromatic diamine, or a polyamine such as an aliphatic polyether amine, but is not limited to these amines. In addition, these amine components may be used alone or in combination.

Examples of the diamine include: 1-core diamine such as p-phenylenediamine (PPD), 1, 3-diaminobenzene, 2, 4-toluenediamine, 2, 5-toluenediamine, and 2, 6-toluenediamine, diaminodiphenyl ethers such as 4,4' -diaminodiphenyl ether, 3' -diaminodiphenyl ether, and 3,4' -diaminodiphenyl ether, and the like 4,4' -diaminodiphenylmethane, 3' -dimethyl-4, 4' -diaminobiphenyl, 2' -bis (trifluoromethyl) -4,4' -diaminobiphenyl, 3' -dimethyl-4, 4' -diaminodiphenylmethane, 3',5,5' -tetramethyl-4, 4' -diaminodiphenylmethane, bis (4-aminophenyl) sulfide, 4' -diaminobenzidine, 3' -dichlorobenzidine 3,3' -dimethylbenzidine (o-tolidine), 2' -dimethylbenzidine (m-tolidine), 3' -dimethoxybenzidine, 2' -dimethoxybenzidine, 3' -diaminodiphenyl ether 3,3' -dimethylbenzidine (o-tolidine), 2' -dimethylbenzidine (m-tolidine), and 3,3' -dimethoxy benzidine, 2' -dimethoxy benzidine, 3' -diaminodiphenyl ether, 2, 2-bis (4-aminophenyl) -1, 3-hexafluoropropane 3,3 '-diaminodiphenyl sulfoxide, 3,4' -diaminodiphenyl sulfoxide 2, 2-bis (4-aminophenyl) -1, 3-hexafluoropropane, 3 '-diaminodiphenyl sulfoxide, 3,4' -diaminodiphenyl sulfoxide diamines having 2 benzene nuclei such as 4,4 '-diaminodiphenyl sulfoxide, 3' -dicarboxy-4, 4 '-diaminodiphenyl methane, etc 1, 3-bis (3-aminophenyl) benzene, 1, 3-bis (4-aminophenyl) benzene, 1, 4-bis (3-aminophenyl) benzene, 1, 4-bis (4-aminophenyl) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (3-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) -4-trifluoromethylbenzene, 3' -diamino-4- (4-phenyl) phenoxybenzophenone, 3 '-diamino-4, 4' -bis (4-phenylphenoxy) benzophenone, 1, 3-bis (3-aminophenylsulfide) benzene, 3-core diamines such as 1, 3-bis (4-aminophenylsulfide) benzene, 1, 4-bis (4-aminophenylsulfide) benzene, 1, 3-bis (3-aminophenylsulfide) benzene, 1, 3-bis (4-aminophenylsulfide) benzene, 1, 4-bis (4-aminophenylsulfide) benzene, 1, 3-bis [ 2- (4-aminophenyl) isopropyl ] benzene, 1, 4-bis [ 2- (4-aminophenyl) isopropyl ] benzene, 3 '-bis (3-aminophenoxy) biphenyl, 3' -bis (4-aminophenoxy) biphenyl, 4 '-bis (3-aminophenoxy) biphenyl, 4' -bis (4-aminophenoxy) biphenyl, bis [ 3- (3-aminophenoxy) phenyl ] ether, bis [ 3- (4-aminophenoxy) phenyl ] ether, bis [ 4- (3-aminophenoxy) phenyl ] ether, bis [ 4- (4-aminophenoxy) phenyl ] ether, bis [ 4- (3-aminophenoxy) phenyl ] ketone, bis [ 3- (4-aminophenoxy) phenyl ] ketone, bis [ 4- (3-aminophenoxy) phenyl ] ketone Bis [ 3- (3-aminophenoxy) phenyl ] sulfide, bis [ 3- (4-aminophenoxy) phenyl ] sulfide, bis [ 4- (3-aminophenoxy) phenyl ] sulfide, bis [ 4- (4-aminophenoxy) phenyl ] sulfide, bis [ 3- (3-aminophenoxy) phenyl ] sulfone, bis [ 3- (4-aminophenoxy) phenyl ] sulfone, bis [ 4- (3-aminophenoxy) phenyl ] sulfone, bis [ 4- (4-aminophenoxy) phenyl ] sulfone, bis [ 3- (3-aminophenoxy) phenyl ] methane, bis [ 3- (4-aminophenoxy) phenyl ] methane bis [ 4- (3-aminophenoxy) phenyl ] methane, bis [ 4- (4-aminophenoxy) phenyl ] methane, 2-bis [ 3- (3-aminophenoxy) phenyl ] propane, 2-bis [ 3- (4-aminophenoxy) phenyl ] propane, 2-bis [ 4- (3-aminophenoxy) phenyl ] propane 2, 2-bis [ 4- (4-aminophenoxy) phenyl ] propane, 2-bis [ 3- (3-aminophenoxy) phenyl ] 1, 3-hexafluoropropane 2, 2-bis [ 3- (4-aminophenoxy) phenyl ] -1, 3-hexafluoropropane, aromatic diamines such as diamines having 4 benzene nuclei such as 2, 2-bis [ 4- (3-aminophenoxy) phenyl ] -1, 3-hexafluoropropane and 2, 2-bis [ 4- (4-aminophenoxy) phenyl ] -1, 3-hexafluoropropane 1, 2-diaminoethane, 1, 3-diaminopropane, 1, 4-diaminobutane aliphatic diamines such as 1, 5-diaminopentane, 1, 6-diaminohexane, 1, 7-diaminoheptane, 1, 8-diaminooctane, 1, 9-diaminononane, 1, 10-diaminodecane, 1, 11-diaminoundecane, 1, 12-diaminododecane, and 1, 2-diaminocyclohexane, examples of the aliphatic polyether amine include ethylene glycol and/or propylene glycol based polyamines. In addition, as described below, an amine having a carboxyl group may be used.

Examples of the amine having a carboxyl group include: diaminobenzoic acids such as 3, 5-diaminobenzoic acid, 2, 5-diaminobenzoic acid, and 3, 4-diaminobenzoic acid, aminophenoxy benzoic acids such as 3, 5-bis (3-aminophenoxy) benzoic acid, and 3, 5-bis (4-aminophenoxy) benzoic acid, 3' -diamino-4, 4' -dicarboxybiphenyl, 4' -diamino-3, 3' -dicarboxybiphenyl, 4' -diamino-2, 2', carboxydiphenyl compounds such as 5,5' -tetracarboxydiphenyl, 3' -diamino-4, 4' -dicarboxydiphenyl methane, 3' -dicarboxydiphenyl-4, 4' -diaminodiphenyl methane 2, 2-bis [ 3-amino-4-carboxyphenyl ] propane, 2-bis [ 4-amino-3-carboxyphenyl ] propane, 2-bis [ 3-amino-4-carboxyphenyl ] hexafluoropropane, 4' -diamino-2, 2', carboxydiphenyl alkanes such as carboxydiphenyl methane, e.g., 5' -tetracarboxylic diphenyl methane, carboxydiphenyl alkanes such as 3,3' -diamino-4, 4' -dicarboxydiphenyl ether, 4' -diamino-3, 3' -dicarboxydiphenyl ether, 4' -diamino-2, 2', 5' -tetracarboxylic diphenyl ether, and 3,3' -diamino-4, 4' -dicarboxydiphenyl sulfone, diphenyl sulfone compounds such as 4,4' -diamino-3, 3' -dicarboxydiphenyl sulfone, 4' -diamino-2, 2' -dicarboxydiphenyl sulfone, and 4,4' -diamino-2, 2', 5' -tetracarboxylic acid diphenyl sulfone, bis [ (carboxyphenyl) phenyl ] alkane compounds such as 2, 2-bis [4- (4-amino-3-carboxyphenoxy) phenyl ] propane, and bis [ (carboxyphenoxy) phenyl ] sulfone compounds such as 2, 2-bis [4- (4-amino-3-carboxyphenoxy) phenyl ] sulfone.

As the isocyanate component, there may be used diisocyanates such as aromatic diisocyanates and isomers thereof, polymers, aliphatic diisocyanates, alicyclic diisocyanates and isomers thereof, and other general-purpose diisocyanates, but not limited to these isocyanates. In addition, these isocyanate components may be used alone or in combination.

Examples of the diisocyanate include aromatic diisocyanates such as 4,4' -diphenylmethane diisocyanate, toluene diisocyanate, naphthalene diisocyanate, xylene diisocyanate, diphenyl sulfone diisocyanate, and diphenyl ether diisocyanate, aliphatic diisocyanates such as isomers, polymers, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and xylene diisocyanate, alicyclic diisocyanates and isomers obtained by hydrogenating the aromatic diisocyanate, and other general-purpose diisocyanates.

For introducing the imide ring into the alkali-soluble resin, alkali-soluble polymers, oligomers, or monomers having any one or both of a carboxyl group and an acid anhydride group, which are conventionally known, may be used, and for example, the alkali-soluble resins conventionally known may be used alone or in combination with the carboxylic anhydride component and reacted with the amine/isocyanate.

For the synthesis of polyimide, polyamideimide or polyamide, a known and commonly used organic solvent can be used. The organic solvent is not particularly limited as long as it does not react with the carboxylic acid anhydride, amine, or isocyanate as the raw material and dissolves these raw materials. Specific examples thereof include amide solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, cyclic ester solvents such as gamma-butyrolactone, gamma-valerolactone, delta-valerolactone, gamma-caprolactone, epsilon-caprolactone, alpha-methyl-gamma-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, lactam solvents such as caprolactam, ether solvents such as dioxane, glycol solvents such as triethylene glycol, m-cresol, p-cresol, 3-chlorophenol, 4-chlorophenol, phenol solvents such as 4-methoxyphenol and 2, 6-dimethylphenol, acetophenone, 1, 3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide, tetramethylurea, and the like. Further, other general organic solvents, that is, phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpentine, mineral essential oil, petroleum naphtha-based solvents, and the like may be added for use. Among them, aprotic solvents such as N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and γ -butyrolactone are preferable from the viewpoint of high solubility of the raw materials.

In addition, for the polyimide, polyamideimide or polyamide, the acid value is preferably 20 to 200mgKOH/g, more preferably 60 to 150mgKOH/g, in order to cope with the development step. When the acid value is 20mgKOH/g or more, the solubility in alkali increases, the development becomes good, and the degree of crosslinking with the heat-curable component after light irradiation becomes high, so that a sufficient development contrast can be obtained. When the acid value is 200mgKOH/g or less, so-called hot fogging in a PEB (post-exposure bake (POST EXPOSURE BAKE)) step after light irradiation, which will be described later, can be suppressed, and a process margin (process margin) can be increased.

In addition, regarding the molecular weight of polyimide, polyamideimide or polyamide, if the developability and cured coating film characteristics are taken into consideration, the mass average molecular weight is preferably 1000 to 100000, more preferably 2000 to 50000. When the molecular weight is 1000 or more, sufficient development resistance and cured physical properties can be obtained after exposure to light and PEB. When the molecular weight is 100000 or less, the alkali solubility increases, and the developability improves.

In addition, when a photobase generator is used in a resin composition containing polyimide, polyamideimide or polyamide, the photobase generator and the thermoreactive compound are usually contained in addition to the alkali-soluble resin, and when a photopolymerization initiator is used, the photopolymerization initiator and the compound having an ethylenically unsaturated bond are contained in addition to the alkali-soluble resin. As the resin component, a carboxyl group-containing urethane resin, a carboxyl group-containing novolak resin, or the like may be used in combination.

The blending amount of such polyimide, polyamideimide or polyamide is preferably 20 to 90% by mass, more preferably 25 to 80% by mass, based on the total solid content of the resin composition constituting the resin layer (B).

The photobase generator is a compound of 1 or more alkaline substances that can function as a catalyst for polymerization of a thermally reactive compound described below by changing the molecular structure or cleaving the molecules by irradiation with ultraviolet light, visible light, or the like. Examples of the alkaline substance include secondary amines and tertiary amines.

Examples of the photobase generator include α -aminoacetophenone compounds, oxime ester compounds, compounds having substituents such as acyloxyimino groups, N-formylated aromatic amino groups, N-acylated aromatic amino groups, nitrobenzyl carbamate groups, and alkoxybenzyl carbamate groups. Among them, oxime ester compounds and α -aminoacetophenone compounds are preferable. The α -aminoacetophenone compound is particularly preferably one having 2 or more nitrogen atoms.

As other photobase generators, WPBG-018 (trade name: 9-tetrahydroxymethyl N, N' -diethyl arbamate), WPBG-027 (trade name: 1- (2-hydroxyphenoyl) -2-propenyl) piperidine), WPBG-082 (trade name: guanidinium 2- (3-benzoylphenoyl) propionate), WPBG-140 (trade name: 1- (antimicrobial-2-yl) ethyl imidazolecarboxylate) and the like can be used.

The α -aminoacetophenone compound has a benzoin ether bond in a molecule, and if irradiated with light, causes cleavage in the molecule to generate an alkaline substance (amine) that exerts a curing catalyst. Specific examples of the α -aminoacetophenone compound include commercially available compounds such as (4-morpholinobenzoyl) -1-benzyl-1-dimethylaminopropane (Omnirad 369, trade name, manufactured by IGM Resins), 4- (methylthiobenzoyl) -1-methyl-1-morpholinoethane (Omnirad 907, trade name, manufactured by IGM Resins), 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone (Omnirad 379, trade name, manufactured by IGM Resins) and solutions thereof.

The oxime ester compound may be any compound that generates an alkaline substance by irradiation with light. As the oxime ester compound, there may be mentioned, as commercial products, irgacureOXE01, irgacureOXE02, N-1919, NCI-831, etc. manufactured by BASF Japan Co., ltd. Further, a compound having 2 oxime ester groups in the molecule as described in Japanese patent No. 4344400 may be suitably used.

Examples of the carbazole oxime ester compounds include those described in Japanese patent application laid-open No. 2004-359639, japanese patent application laid-open No. 2005-097141, japanese patent application laid-open No. 2005-220097, japanese patent application laid-open No. 2006-160634, japanese patent application laid-open No. 2008-094770, japanese patent application laid-open No. 2008-509967, japanese patent application laid-open No. 2009-040762, and Japanese patent application laid-open No. 2011-80036.

The photobase generator may be used alone or in combination of 1 or 2 or more. The blending amount of the photobase generator in the resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.1 to 30 parts by mass, relative to 100 parts by mass of the alkali-soluble resin of the resin layer (B). When the amount is 0.1 parts by mass or more, the contrast of development resistance of the irradiated portion/non-irradiated portion can be obtained satisfactorily. When the amount is 40 parts by mass or less, the cured product properties are improved.

The thermally reactive compound is a resin having a functional group capable of undergoing a heat-based curing reaction, and examples thereof include epoxy resins, polyfunctional oxetane compounds, and the like.

The epoxy resin is a resin having an epoxy group, and any known epoxy resin can be used. Specifically, examples thereof include a 2-functional epoxy resin having 2 epoxy groups in the molecule, and a multifunctional epoxy resin having a plurality of epoxy groups in the molecule. It is to be noted that a hydrogenated 2-functional epoxy compound may be used.

Examples of the epoxy compound include bisphenol a type epoxy resin, brominated epoxy resin, novolac type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol a type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, alicyclic epoxy resin, trihydroxyphenyl methane type epoxy resin, xylenol type or biphenol type epoxy resin, and a mixture thereof; bisphenol S-type epoxy resins, bisphenol A novolac-type epoxy resins, tetraphenolethane-type epoxy resins, heterocyclic epoxy resins, diglycidyl phthalate resins, tetraglycidyl ditolyl ethane resins, naphthalene group-containing epoxy resins, epoxy resins having dicyclopentadiene skeleton, glycidyl methacrylate copolymerized epoxy resins, cyclohexylmaleimide and glycidyl methacrylate copolymerized epoxy resins, CTBN modified epoxy resins, and the like.

Examples of the other liquid 2-functional epoxy resin include alicyclic epoxy resins such as vinylcyclohexene diepoxide, (3 ',4' -epoxycyclohexylmethyl) -3, 4-epoxycyclohexane carboxylate, and (3 ',4' -epoxy-6 ' -methylcyclohexylmethyl) -3, 4-epoxy-6-methylcyclohexane carboxylate. These epoxy resins may be used alone or in combination of 1 kind or 2 or more kinds.

Examples of the polyfunctional oxetane compound include polyfunctional oxetanes such as bis [ (3-methyl-3-oxetanylmethoxy) methyl ] ether, bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] ether, 1, 4-bis [ (3-methyl-3-oxetanylmethoxy) methyl ] benzene, 1, 4-bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] benzene, (3-methyl-3-oxetanylmethyl) acrylate, (3-ethyl-3-oxetanylmethyl) acrylate, (3-methyl-3-oxetanylmethyl) methyl methacrylate, and (3-ethyl-3-oxetanylmethyl) methacrylate, and oligomers or copolymers thereof: and etherates of oxetane alcohol with resins having hydroxyl groups such as novolak resins, poly (p-hydroxystyrene), cardo bisphenols, calixarenes, resorcinol calixarenes, and silsesquioxanes. Further, copolymers of an unsaturated monomer having an oxetane ring and an alkyl (meth) acrylate and the like can be mentioned.

As the compounding amount of the above heat-reactive compound, the equivalent ratio to the alkali-soluble resin of the resin layer (B) (alkali-soluble group such as carboxyl group: heat-reactive group such as epoxy group) is preferably 1:0.1 to 1:10. by setting the compounding ratio to the range, development becomes good, and a fine pattern can be easily formed. The above equivalent ratio is more preferably 1:0.2 to 1:5.

as the photopolymerization initiator, a known photopolymerization initiator can be used, and examples thereof include α -aminoacetophenone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds.

In particular, when used in the PEB step after light irradiation, which will be described later, a photopolymerization initiator having a function as a photobase generator is suitable. In the PEB step, a photopolymerization initiator and a photobase generator may be used in combination.

As the compound having an ethylenically unsaturated bond, known compounds can be used, including: hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono-or diacrylates of glycols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, and propylene glycol; polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol and trihydroxyethyl isocyanurate, and polyhydric acrylic esters such as ethylene oxide adducts and propylene oxide adducts thereof; phenoxy acrylates, bisphenol a diacrylates, and acrylates such as ethylene oxide adducts and propylene oxide adducts of these phenols.

The amount of the compound having an ethylenically unsaturated bond is preferably 5 to 100 parts by mass, more preferably 10 to 70 parts by mass, based on 100 parts by mass of the alkali-soluble resin of the resin layer (B).

The elastic modulus measured after 24 hours of standing at room temperature of 23℃as a cured product of the resin layer (B) is preferably in the range of more than 1.5GPa and 3.5GPa or less. Thus, the cured product of the laminated structure of the present invention has excellent bending resistance.

For the purpose of improving the flexibility and touch dryness of the cured product obtained, other commonly known polymer resins may be contained in the resin composition constituting the resin layers (a) and (B).

Examples of such a polymer resin include cellulose-based, polyester-based, phenoxy-resin-based polymers, polyvinyl acetal-based, polyvinyl butyral-based, polyamide-based, polyamideimide-based binder polymers, block copolymers, and elastomers. The polymer resin may be used alone or in combination of at least 2 kinds.

In addition, the resin composition constituting the resin layer (a) and the resin layer (B) may contain an inorganic filler in order to suppress curing shrinkage of the cured product and improve properties such as adhesion and hardness.

Examples of such inorganic fillers include barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, alumina, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, and noriburg silica.

Further, a known and commonly used colorant may be blended in the resin composition constituting the resin layer (a) and the resin layer (B). Conventionally, when the coloring power of a pattern layer is insufficient at the edge portion of a copper circuit in a printed wiring board, copper changes in color in a thermal history after formation of the pattern layer, and only a thin portion is visible in appearance. As a representative thermal history, there are: thermal curing of the mark, warp correction, preheating before installation, etc. Therefore, conventionally, a large amount of colorant is blended in a pattern layer to improve the coloring power, thereby eliminating the problem that discoloration occurs only in the edge portion of a copper circuit. However, the colorant has light absorbability, and thus, light transmission to deep is hindered. As a result, undercut is likely to occur in the colorant-containing composition, and therefore, it is difficult to obtain sufficient adhesion.

In contrast, when the resin composition contains the photobase generator, the alkali chemically grows deep in each layer, and the resin composition can be sufficiently cured deep in each layer, so that even when the resin composition contains the colorant, a pattern layer excellent in coverage of a copper circuit and adhesion can be formed.

In the resin composition constituting the resin layer (a) and the resin layer (B), an organic solvent may be used for preparing the resin composition and for adjusting the viscosity for application to a substrate or a carrier film. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum solvents. The organic solvent may be used alone or as a mixture of 2 or more.

The resin composition constituting the resin layer (a) and the resin layer (B) may further contain a mercapto compound, an adhesion promoter, an antioxidant, an ultraviolet absorber, and the like, as necessary. They may use commonly used substances known in the field of electronic materials. Further, known and commonly used thickeners such as fine silica powder, hydrotalcite, organobentonite and montmorillonite, antifoaming agents such as silicone, fluorine and polymer, leveling agents, silane coupling agents and additives such as rust inhibitors may be suitably blended.

The laminated structure of the present invention can be used for at least one of a bent portion and a non-bent portion of a flexible printed circuit board, and is suitably used for both, whereby the cost and workability can be improved and a flexible printed circuit board having sufficient durability against bending can be obtained. Specifically, the laminated structure of the present invention can be used for applications of flexible printed circuit boards such as coverlays, solder resists, and interlayer insulating materials.

The resin compositions constituting the resin layers (a) and (B) of the laminated structure of the present invention can be obtained by kneading the respective components by, for example, three-roll milling.

[ cured product ]

The cured product of the present invention is obtained by curing a resin composition or a laminated structure constituting the resin layer (a) and the resin layer (B) respectively, for example, through a lamination step, an exposure step, a development step, and a thermal curing (post-curing) step. The heating temperature in the heat curing (post-curing) step is, for example, 140 to 180℃and the heating time is, for example, 20 to 120 minutes.

Preferably, the cured product is laminated on a substrate such as a printed circuit board with the resin layer (a) interposed therebetween, and after each of the steps such as the exposure step, a laminate is formed from the obtained cured product and a seed layer formed by sputtering on the cured product in the order of Ni layer and Cu layer, and the laminate exhibits a tensile strength of 5.0N/cm or more in adhesion between the seed layer and the cured product in a 90 ° peel test of the seed layer. By having a tensile strength of 5.0N/cm or more, the adhesion of the laminated structure to a metal layer such as a conductor layer becomes sufficient. The seed layer of Ni/Cu formed by the above sputtering is formed as follows: at a sputtering pressure of 7.0X10 ^-1 Processing at Pa, 100W, and 10 min to form 50nmNi seed layer, and sputtering at 7.0X10 g ^-1 Treatment at Pa, 300W, 15 minutes formed a Cu seed layer of 500nm.

[ Dry film ]

The dry film of the invention is preferably supported or protected on at least one side by a film, such as a carrier film, of the laminated structure.

The dry film of the present invention can be produced, for example, as follows. The resin composition forming the resin layer (a) and the resin layer (B) is diluted with an organic solvent to an appropriate viscosity, and the resin composition forming the resin layer (B) is first applied to a carrier film at a uniform thickness by a known technique such as a comma coater according to a conventional method. Thereafter, the coated composition is dried at a temperature of usually 40 to 130 ℃ for 1 to 30 minutes, whereby the resin layer (B) can be formed on the carrier film. Next, the resin composition forming the resin layer (a) was applied to the resin layer (B) in a uniform thickness as in the case of the resin layer (B), and dried at a temperature of 40 to 130 ℃ for 1 to 30 minutes, thereby forming the resin layer (a) on the resin layer (B), to obtain the laminated structure of the present invention.

As the carrier film, a conventionally known plastic film can be suitably used,

For example, a polyester film such as polyethylene terephthalate (PET), a polyimide film, a polyamideimide film, a polypropylene film, a polystyrene film, or the like can be used. The thickness of the support film is not particularly limited, but is usually suitably selected in the range of 10 to 150. Mu.m.

After the laminated structure of the present invention is formed on the carrier film, a protective film capable of peeling is preferably laminated on the surface of the resin layer for the purpose of preventing dust from adhering to the surface of the resin layer or the like. Examples of the releasable protective film include a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, and a surface-treated paper. The protective film may be one that has less adhesion between the resin layer and the carrier film when the protective film is peeled off.

[ printed Circuit Board ]

The cured product of the laminated structure of the present invention as described above can be used particularly suitably as a solder resist layer, an interlayer insulating material, a cover layer, a solder dam (solder dam), a through hole of a via hole, and a filler material for a hole portion of a multilayer flexible printed circuit board.

For example, a printed circuit board, for example, a multilayer flexible printed circuit board includes a portion obtained by laminating a cured product obtained from the laminated structure of the present invention 2 or more times. In other words, the multilayer structure of the present invention may be laminated on a part or the whole of the printed circuit board according to the structure or characteristics of the board.

[ manufacturing of Flexible printed Circuit Board ]

In the present invention, the laminated structure of the present invention is formed on a flexible printed circuit board with a resin layer (a) interposed therebetween, patterned by light irradiation, and patterned simultaneously with a developer to form a so-called insulating film, whereby a printed circuit board can be manufactured. The manufacturing method includes a lamination step, an exposure step, a heating step, a developing step, and a thermal curing (post-curing) step, as will be described later.

[ laminating step ]

In the lamination step, a laminated structure of the present invention is laminated on a flexible printed circuit board on which a conductor circuit is formed, with a resin layer (a) interposed therebetween, to form a laminated structure including the resin layer (a) formed of a resin composition containing an alkali-soluble resin or the like; and a resin layer (B) formed on the resin layer (A) from a resin composition containing 1 or more components selected from the group consisting of polyimide, polyamideimide and polyamide.

Here, the layers constituting the laminated structure may be formed directly by, for example, sequentially applying resin compositions for forming the resin layer (a) and the resin layer (B) in this order on the flexible printed circuit board and drying the resin compositions. Alternatively, the resin layer (a) and the resin layer (B) may be laminated on the flexible printed circuit board by laminating a 2-layer laminated structure to form a dry film with the resin layer (a) interposed therebetween. In this case, either one or both sides of the laminated structure may be supported or protected by the film in advance. Examples thereof include: a carrier film is applied to the resin layer (B), and a protective film is applied to the resin layer (a). The protective film and the carrier film may be suitably peeled off and used.

From the viewpoint of the strength of the coating film, the interface between the layers may be compatible.

The method of applying the resin composition of the resin layer (a) or the resin layer (B) to the substrate may be a known method such as a blade coater, a lip coater, a comma coater, or a film coater. The drying method may be a known method such as a method of bringing hot air in a dryer into convection contact with a heat source having a steam heating system, such as a hot air circulation type drying furnace, an IR furnace, a hot plate, or a convection oven, or a method of blowing the hot air from a nozzle to a support.

Here, as the substrate, a flexible printed circuit substrate on which a circuit is formed in advance is exemplified. In addition to the original effects, a further layer may be provided between the resin layer (a) and the resin layer (B) in order to obtain further effects.

[ Exposure procedure ]

In this step, the photopolymerization initiator contained in the resin layer (a) and the resin layer (B) is activated into a negative pattern by irradiation with active energy rays, and the exposed portion is cured. As the exposure machine, a direct drawing apparatus, an exposure machine equipped with a metal halide lamp, or the like can be used. As the pattern-shaped mask for exposure, a negative-type mask can be used.

As the active energy ray used in the exposure, a laser light having a maximum wavelength in the range of 350 to 450nm or scattered light is preferably used. By setting the maximum wavelength to this range, the photopolymerization initiator can be activated efficiently. The exposure amount varies depending on the film thickness, but may be generally 50 to 1500mJ/cm ² 。

Examples of the light irradiator used for active energy ray irradiation include a direct-imaging device (for example, a laser direct imaging device that directly draws an image with laser light using CAD data from a computer), a light irradiator equipped with a metal halide lamp, a light irradiator equipped with a (ultra) high-pressure mercury lamp, a light irradiator equipped with a mercury short-arc lamp, and a direct-imaging device using an ultraviolet lamp such as a (ultra) high-pressure mercury lamp. The patterned active energy ray irradiation mask may be a negative type mask.

[ heating (POST EXPOSURE BAKE; abbreviated as PEB) Process ]

In the PEB step, after exposure, the resin layer including the resin layer (a) and the resin layer (B) is heated to cure the exposed portion. By this step, the resin layer (B) can be cured deep by using a photopolymerization initiator having a function as a photobase generator or a base generated in the exposure step of the resin layer (B) formed by using a composition of the photopolymerization initiator and the photobase generator.

The heating temperature is, for example, 80 to 140 ℃. The heating time is, for example, 10 to 100 minutes. By setting the heating temperature to 80 ℃ or higher, the light irradiation portion can be sufficiently cured. On the other hand, by setting the heating temperature to 140 ℃ or lower, only the light irradiation portion can be selectively cured.

Since the curing in the PEB step is, for example, a ring-opening reaction of an epoxy resin by a thermal reaction, strain and curing shrinkage can be suppressed as compared with the case where curing is performed by a photo radical reaction.

[ developing Process ]

In this step, the unexposed portion is removed by alkali development, and a negative pattern-like insulating film, particularly a cap layer and a solder resist layer, is formed. The developing method may be a known method such as dipping method, spraying method, or brush coating method. As the developer, an aqueous alkali solution such as sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, ammonia, amines such as ethanolamine, imidazoles such as 2-methylimidazole, aqueous tetramethylammonium hydroxide (TMAH), or a mixture thereof may be used.

After the development step, the insulating film may be further irradiated with active energy rays. Thus, the photoacid generator remaining without being activated in the pattern layer in the active energy ray irradiation step can be activated to generate alkali. The exposure amount at this time may be the same as in the case of the exposure step described above.

[ Heat curing (post-curing) procedure ]

After the development step, a heat curing (post-curing) step is preferably further included. The heat curing step is a step of performing heat curing (post curing) as needed to sufficiently heat-cure the pattern layer. In the case where the 2 nd light irradiation step and the heat curing step are performed simultaneously after the developing step, the heat curing step is preferably performed after the 2 nd light irradiation step. The heating temperature is, for example, 140℃to 180 ℃. The heating time is, for example, 20 to 120 minutes.

Hereinafter, one embodiment of the present application is specifically illustrated according to examples, but it is needless to say that the scope of the application according to the claims of the present application is not limited thereto.

The terms "part" and "%" are based on mass unless otherwise specified.

Examples

The resins for forming the resin layer (a) and the resin layer (B) in the present application and the resin composition containing the resins were prepared as follows, respectively.

Synthesis example 1: synthesis of carboxyl group-containing polyurethane resin

2400g (3 moles) of a polycarbonate diol (T5650J, manufactured by number average molecular weight 800;ASAHI KASEI CHEMICALS CORPORATION) derived from 1, 5-pentanediol and 1, 6-hexanediol, 603g (4.5 moles) of dimethylolpropionic acid, and 238g (2.6 moles) of 2-hydroxyethyl acrylate as a monohydroxy compound were charged into a reaction vessel equipped with a stirring device, a thermometer, and a condenser. Then, 1887g (8.5 moles) of isophorone diisocyanate (as polyisocyanate) was charged, and the reaction vessel was heated to 60℃with stirring, stopped, and heated again at the point of starting to decrease the temperature in the reaction vessel, and stirring was continued at 80℃to confirm the absorption spectrum of isocyanate groups in the infrared absorption spectrum (2280 cm ^-1 ) Vanish and end the reaction. Thereafter, carbitol acetate was added so that the solid content became 50 mass%. The acid value of the solid content of the obtained carboxyl group-containing polyurethane resin was 50mgKOH/g.

Synthesis example 2: synthesis of alkali-soluble resin solution having imide Ring

To a detachable three-necked flask equipped with a stirrer, a nitrogen inlet tube, a fractionating ring and a condensing ring, 12.2g of 3, 5-diaminobenzoic acid, 8.2g of 2,2 '-bis [4- (4-aminophenoxy) phenyl ] propane, 30g of N-methyl-2-pyrrolidone (NMP), 30g of gamma-butyrolactone, 27.9g of 4,4' -oxybisphthalic anhydride and 3.8g of trimellitic anhydride were charged, and stirred under a nitrogen atmosphere at room temperature and 100rpm for 4 hours. Then, 20g of toluene was added thereto, and toluene and water were distilled off at a silicone bath temperature of 180℃and 150rpm while stirring for 4 hours, to obtain an alkali-soluble resin solution having an imide ring. Thereafter, gamma-butyrolactone was added so that the solid content became 30 mass%. The solid content acid value of the obtained resin solution was 86mgKOH/g, and Mw was 10000.

Synthesis example 3: synthesis of alkali-soluble resin solution with polyamideimide

3.8g of 3, 5-diaminobenzoic acid, 6.98g of 2,2' -bis [4- (4-aminophenoxy) phenyl ] propane, 8.21g of JEFFAMINE XTJ-542 (molecular weight 1025.64; manufactured by HUNTSMAN Co., ltd.) and 86.49g of gamma-butyrolactone were charged into a detachable three-necked flask equipped with a stirrer, a nitrogen inlet pipe, a fractionating ring and a condenser ring, and dissolved at room temperature. Then, 17.84g of cyclohexane-1, 2, 4-tricarboxylic acid-1, 2-anhydride and 2.88g of trimellitic anhydride were charged, and the mixture was kept at room temperature for 30 minutes. Then, 30g of toluene was added thereto, the temperature was raised to 160℃and the mixture was stirred for 3 hours while toluene and water were distilled off, and then the mixture was cooled to room temperature to obtain an imide solution. To the obtained imide solution, 9.61g of trimellitic anhydride and 17.45g of trimethylhexamethylene diisocyanate were added, and the mixture was stirred at 160℃for 32 hours. Thus, a polyamideimide resin solution having a carboxyl group (solid content 40 mass%) was obtained. The acid value of the obtained resin (solid content) was 83.1mgKOH and Mw was 4300.

The resin compositions A1 to A6 for forming the resin layer (a) and the resin compositions B1 to B6 for forming the resin layer (B) were prepared by premixing the components and the compounding amounts (solid components) shown in the following tables 1 to 1 and 1 to 2 in a mixer and kneading the components and the solid components by a three-roll mill.

TABLE 1

TABLE 1-1 compositions (unit: parts by mass) of resin compositions A1 to A6

TABLE 2

Table 1-2 compositions (unit: parts by mass) of resin compositions B1 to B6

Details of the components in tables 1-1 and 1-2 are as follows.

The following is 1) polyurethane resin: synthesis example 1 described above

2) imide resin: reference is made to the above synthetic example 2

3) an amideimide resin: reference is made to the above synthesis example 3

The target is 4) ZFR-1401H: acid-modified bisphenol F type epoxy acrylate having an acid value of 98mgKOH/g (manufactured by Japanese chemical Co., ltd.)

The method comprises the following steps: ethoxylated bisphenol A dimethacrylate (New Zhongcun chemical industry Co., ltd.)

6) Aronix M350: trimethylolpropane EO-modified triacrylate (manufactured by Toyama Synthesis Co., ltd.)

7) jER1001: bisphenol A type epoxy resin having an epoxy equivalent of 450 to 500 and being solid at ordinary temperature (Mitsubishi chemical Co., ltd.)

8) YX-7400: epoxy resin, epoxy equivalent 440g/eq, liquid at normal temperature (Mitsubishi chemical Co., ltd.)

The target is 9) jER834: bisphenol A type epoxy resin having an epoxy equivalent weight of 230 to 270g/eq (Mitsubishi chemical Co., ltd.)

The rare earth: bisphenol A type epoxy resin having an epoxy equivalent of 184 to 194g/eq and being liquid at ordinary temperature (Mitsubishi chemical Co., ltd.)

The target is 11) Omnirad 379: alkylphenone photopolymerization initiator (manufactured by IGM Resins Co., ltd.)

The rare earth complex is 12) 2,4, 6-trimethylbenzoyl diphenyl phosphine oxide: acyl phosphine oxide photopolymerization initiator

The target is 13) Irgacure OXE-02: oxime photopolymerization initiator (BASF Japan Co., ltd.)

[ production of Dry films of examples 1 to 11 and comparative examples 1 to 11 ]

Resin compositions B1 to B6 constituting the resin layer (B) shown in Table 1-2 were applied to a PET-made carrier film so that the film thickness after drying was 1 to 20. Mu.m. Thereafter, the resin layers (B) were each formed by drying in a hot air circulation type drying oven at 90℃for 30 minutes. Then, resin compositions A1 to A6 constituting the resin layer (A) shown in Table 1-1 were applied to the surface of the resin layer (B) so that the film thickness after drying became 7 to 150. Mu.m. Thereafter, the resin layers (a) were formed by drying in a hot air circulation type drying oven at 90 ℃/30 minutes, and dry films of examples 1 to 11 and comparative examples 1 to 11, each comprising a carrier film, a resin layer (B) and a resin layer (a), were produced.

Test example 1 measurement of elastic modulus

Single-layer dry films corresponding to the resin compositions A1 to A6 and the compositions B1 to B6 were prepared, and these dry films were laminated on a release PET film at 90℃under a lamination pressure of 0.5MPa for 50 seconds by a vacuum laminator, and then, as an exposure step, a metal halide lamp-mounted exposure device (HMW 680GW (metal halide lamp, scattered light) (manufactured by ORC Co.) was used at 200mJ/cm ² Exposing to light, heating at 90deg.C for 35 min in a hot air circulation drying furnace, and peeling off the carrier film, and developing with 1wt% Na ₂ CO ₃ after aq.50 seconds, the cured product was thermally cured at 150℃for 60 minutes using a hot air circulation type drying oven as a thermal curing step, and peeled from the release PET film, and was cured according to JIS K7127:1999, the cured product was regarded as a plastic, and the tensile strength in the MD of the cured product was measured (device name: model tensile tester "AGS-G100W" (Shimadzu corporation)), and the elastic modulus after 24 hours at room temperature of 23℃was obtained.

The results are set forth in tables 2-1 and 2-2 below.

Test example 2 measurement of warp resistance

Preparation of the dry films of examples 1 to 11 and comparative examples 1 to 11 by vacuum laminator at 90℃and lamination pressure of 0.5MPa for 50 seconds ]The dry films obtained in (a) were laminated on 10cm square Kapton 100H (DU PONT-toay co., ltd.) with the resin layer (a) interposed therebetween, and then used as an exposure step in an exposure device mounted with a metal halide lampSet (HMW 680GW (Metal halide Lamp, scattered light) (manufactured by ORC Co.), at 200mJ/cm ² Exposing to light, heating at 90deg.C for 35 min in a hot air circulation drying oven as PEB step, and peeling off the carrier film, and passing through 1wt% Na as developing step ₂ CO ₃ after aq.50 seconds, a test piece of a cured product having a resin layer (a) and a resin layer (B) in this order on Kapton 100H was produced by heat curing in a hot air circulation type drying oven at 150 ℃ for 60 minutes as a heat curing step. Then, the degree of floating of the test piece at 4 sides when left standing horizontally was observed, and the total of floating was evaluated as excellent, 1.0cm or more and 2.0cm or less, and 2.0cm or more, as X.

The results are set forth in tables 2-1 and 2-2 below.

Test example 3 bending resistance test

Preparation of the dry films of examples 1 to 11 and comparative examples 1 to 11 by vacuum laminator at 90℃and lamination pressure of 0.5MPa for 50 seconds]The obtained dry films were laminated on both sides of a flexible printed circuit board having a polyimide thickness of 25 μm and a copper thickness of 18 μm and a pattern of L/s=100/100 via a resin layer (a), and then exposed to light of 500mJ/cm by an exposure device (HMW 680GW (metal halide lamp, scattered light) (ORC corporation)) equipped with a metal halide lamp ² The light is irradiated in a negative pattern. Then, a heating treatment was performed at 90℃for 60 minutes in a hot air circulation type drying furnace. Thereafter, the circuit board was immersed in a 30 ℃ and 1 mass% aqueous sodium carbonate solution, and developed for 3 minutes.

Subsequently, a heat treatment was performed at 150 ℃/60 minutes in a hot air circulation type drying furnace to obtain an evaluation substrate having a patterned cured coating film formed thereon. Using the obtained evaluation substrate, bending was performed, and observation was performed visually and with an optical microscope of x 200, and the number of times before the crack entered the cured coating film was recorded. The case of bending 5 times or more is referred to as excellent, the case of bending 3 times or more and less than 5 times is referred to as excellent, and the case of bending 2 times or less is referred to as x.

The results are set forth in tables 2-1 and 2-2 below.

Test example 4 90℃peel test

Preparation of the dry films of examples 1 to 11 and comparative examples 1 to 11 by vacuum laminator at 90℃and lamination pressure of 0.5MPa for 50 seconds]The dry films obtained in (a) were laminated on a copper solid substrate with the resin layer (a) interposed therebetween, and then, as an exposure step, an exposure apparatus (HMW 680GW (metal halide lamp, scattered light) (ORC corporation)) equipped with a metal halide lamp was used at 200mJ/cm ² Exposing to light, heating at 90deg.C for 35 min in a hot air circulation drying oven, and peeling off the carrier film, and developing with 1wt% Na ₂ CO ₃ after aq.50 seconds, the resultant cured product was thermally cured with a hot air circulation drying oven at 150℃for 60 minutes to prepare a seed layer of Ni50nm/Cu300nm by sputtering, and the seed layer was grown to a film thickness of 25. Mu.m by electrolytic copper plating. After annealing at 190℃for 60 minutes, the test piece was formed into a strip having a width of 1cm X10 cm, and a 90℃peel test (apparatus name: model tensile tester "AGS-G100W" (Shimadzu corporation)) was performed in the MD direction.

At a sputtering pressure of 7.0X10 ^-1 A treatment of Pa, 100W, and 10 minutes formed a 50nmNi seed layer on the cured product, and a sputtering pressure of 7.0X10 on the Ni seed layer ^-1 Treatment at Pa, 300W, and 15 minutes formed a Cu seed layer of 500nm, thereby forming the above-mentioned Ni/Cu seed layer formed by sputtering.

The adhesion between the seed layer and the cured product was evaluated as good, 3.0N/cm or more and less than 5.0N/cm, and as low, less than 3.0N/cm.

The results are set forth in tables 2-1 and 2-2 below.

TABLE 3

TABLE 2-1 test results for examples 1-11

TABLE 4

TABLE 2-2 test results for comparative examples 1-11

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Claims

1. A laminated structure is characterized by comprising: a resin layer (A) formed from an alkali-developable resin composition, and a resin layer (B) laminated on the resin layer (A),

the elastic modulus of the cured product of the resin layer (A) is 0.3GPa or more and 1.5GPa or less when measured at 23 ℃, the elastic modulus of the cured product of the resin layer (B) is more than 1.5GPa and 3.5GPa or less when measured at 23 ℃,

2. A cured product obtained from the laminated structure according to claim 1.

3. The cured product according to claim 2, wherein the cured product is formed by laminating a resin layer (a) on a substrate, and the seed layer is formed by sputtering on the cured product in the order of a Ni layer and a Cu layer, and the cured product has a tensile strength of 5.0N/cm or more in adhesion between the seed layer and the cured product in a 90 ° peel test of the seed layer of the laminate of the cured product and the seed layer.

4. A flexible printed circuit board having the cured product according to claim 2.

5. A multilayer flexible printed circuit board having a portion laminated with at least 2 layers or more of the cured product of claim 2.

6. A dry film, wherein at least one side of the laminated structure of claim 1 is supported or protected by a film.

7. An electronic component having the flexible printed circuit board according to claim 4 or 5.