TW201630732A - Laminate structure, dry film, and flexible printed wiring board - Google Patents

Abstract

The present invention provides: a laminate structure and dry film having excellent flexibility and being suitable for an insulating film of a flexible printed wiring board, particularly for a collective formation process of a bending portion (bent portion) and mounting portion (unbent portion); and a flexible printed wiring board having a cured product of said dry film as a protective film. Provided is a laminate structure having a resin layer (A) and a resin layer (B) that is laminated on the flexible printed wiring board with the resin layer (A) interposed therebetween. The resin layer (B) comprises a photosensitive thermosetting resin composition including an alkali-soluble resin, a photopolymerization initiator, and a heat-reactive compound, and the resin layer (A) comprises an alkali-developable resin composition including an alkali-soluble resin and a heat-reactive compound but not including a photopolymerization initiator.

Description

Laminated structure, dry film and flexible printed wiring board

The present invention relates to a laminated structure, a dry film, and a flexible printed wiring board which can be used as an insulating film of a flexible printed wiring board.

In recent years, electronic devices have become smaller and thinner due to the spread of smart phones or tablet terminals, and it is necessary to reduce the space of circuit boards. Therefore, the use of the flexible printed wiring board which can be bent and accommodated is expanded, and even a flexible printed wiring board is required to have higher reliability than the above.

On the other hand, as an insulating film which ensures the reliability of the insulation of the flexible printed wiring board, the polyimine which is excellent in mechanical properties such as heat resistance and buckling property in the bent portion (buckling portion) is widely used. In the coating film of the base (for example, refer to Patent Documents 1 and 2), a mixing process of the finely machinable photosensitive resin composition excellent in electrical insulating properties or solder heat resistance is used in the mounting portion (non-buckling portion).

That is, since the cover film based on polyimine is necessary to be press-formed by a die, it is disadvantageous to the fine wiring. Therefore, it is necessary to use fine wiring as a necessary wafer mounting portion, and partially use available light micro Alkali-developing photosensitive resin composition (solder resist) for photo processing.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 62-263692

Patent Document 2: Japanese Laid-Open Patent Publication No. SHO 63-110224

Therefore, in the manufacturing process of the conventional flexible printed wiring board, the mixing process of the step of bonding the cover film and the step of forming the solder resist cannot be employed, and the problem of cost and workability is poor.

On the other hand, it has been conventionally studied to use an insulating film as a solder resist or an insulating film as a cover film as a solder resist and a cover film for a flexible printed wiring board. However, a material that satisfies both requirements has not been put to practical use.

Therefore, an object of the present invention is to provide an insulating film of a flexible printed wiring board excellent in buckling property, and in particular, a laminated structure suitable for a forming process of a bent portion (buckling portion) and a mounting portion (non-buckling portion), A dry film and a flexible printed wiring board having a cured product thereof as a protective film such as a cover film or a solder resist.

The inventors of the present invention actively review the results to solve the above problems. Thus, the present invention has been completed.

That is, the laminated structure system of the present invention has a resin layer (A) and a laminated structure in which the resin layer (B) is laminated on the flexible printed wiring board via the resin layer (A), and is characterized by The resin layer (B) is composed of a photosensitive thermosetting resin composition containing an alkali-soluble resin, a photopolymerization initiator, and a heat-reactive compound, and the resin layer (A) contains an alkali-soluble resin. It is formed with a thermally reactive compound, a base developing resin composition not containing a photopolymerization initiator.

In the laminated structure of the present invention, the resin layer (A) is preferably made of a resin composition further containing a polymerization inhibiting agent.

The laminated structure of the present invention can be used for at least one of a bent portion and a non-buckled portion of a flexible printed wiring board, and can be used for a cover film, a solder resist, and an interlayer insulating material of a flexible printed wiring board. At least for any use.

Further, the dry film of the present invention is characterized in that at least one side of the laminated structure of the present invention is supported or protected by a film.

Further, the flexible printed wiring board of the present invention is characterized in that a layer of the above-described laminated structure of the present invention is formed on a flexible printed wiring board, and is patterned by light irradiation to form a pattern with a developing liquid. Type of insulating film.

Here, the flexible printed wiring board of the present invention may be formed by sequentially forming the resin layer (A) and the resin layer (B) without using the laminated structure of the present invention, and then patterning by light irradiation. The image liquid forms a pattern at a time. Further, the term "pattern" as used in the present invention means that the shape of the cured product is also That is, the insulating film.

According to the present invention, it is possible to realize an insulating film of a flexible printed wiring board excellent in buckling property, in particular, a laminated structure suitable for a forming process of a bent portion (buckling portion) and a mounting portion (non-buckling portion), and a dry A film and a flexible printed wiring board having a cured product thereof as a protective film such as a cover film or a solder resist.

1‧‧‧Flexible printed wiring board

2‧‧‧Conductor circuit

3‧‧‧ resin layer

4‧‧‧ resin layer

5‧‧‧ mask

Fig. 1 is a view schematically showing an example of a method of manufacturing a flexible printed wiring board of the present invention.

Fig. 2 is a view schematically showing the steps of another example of the method for producing the flexible printed wiring board of the present invention.

Fig. 3 is a photographic view showing the shape of the opening obtained in the examples.

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

(laminated structure)

The laminated structure of the present invention has a resin layer (A) and a resin layer (B) laminated on the flexible printed wiring board via the resin layer (A), and the resin layer (B) is composed of an alkali-soluble resin. And photopolymerization initiator and thermal reaction The photosensitive thermosetting resin composition of the compound is formed, and the resin layer (A) is composed of an alkali-developing resin composition containing an alkali-soluble resin and a thermally reactive compound and not containing a photopolymerization initiator. By.

In the laminated structure of the present invention, the resin layer (A) and the resin layer (B) and the resin layer on the upper layer side may be sequentially formed on the flexible printed wiring board on which the copper circuit is formed on the flexible substrate ( B) is formed of a photosensitive thermosetting resin composition which can be patterned by light irradiation, and the resin layer (B) and the resin layer (A) are patterned once to form a pattern.

In the laminated structure of the present invention, since the resin layer (A) on the side of the printed wiring board does not contain a photopolymerization initiator, it is impossible to pattern in a single layer, but the resin layer of the upper layer is exposed during exposure. The active species such as radicals generated by the photopolymerization initiator contained in (B) are diffused to the resin layer (A) directly below, and the two layers can be simultaneously patterned. In particular, in the method for producing a printed wiring board including a PEB (POST EXPOSURE BAKE) step, the effect is remarkable by thermal diffusion of the above-mentioned active species.

On the other hand, when the photopolymerization initiator is contained in the resin layer (A) on the side of the printed wiring board, since the photopolymerization initiator itself has the property of absorbing light, the polymerization initiation energy toward the deep photopolymerization initiator is further It is difficult to form a high-definition pattern because the light reactivity of the deep portion is lowered, and it is difficult to form a high-definition pattern. However, the present inventors considered that the laminated structure of the present invention is composed of the upper resin layer (B). The effect of the diffusion of the active species can also improve the problem. However, regardless of the presence or absence of diffusion of the above active species, the interaction of the photopolymerization initiator still causes deep photoreactivity (deep sclerosis) Sexuality deteriorates, and there is a problem of undercutting.

Therefore, in the constitution of the laminated structure of the present invention, the resin layer (A) must not contain a photopolymerization initiator, and as a result, it is possible to form a pattern excellent in deep hardenability without undercut.

Further, although the reason is not clear, in the laminated structure of the present invention, the active species are diffused outside the exposed portion due to the influence of the interface, so that the resin layer (A) is easily closed in the shape of the opening. A new problem of halation is caused near the interface with the resin layer (B). This problem is particularly significant in the PEB step. In the laminated structure of the present invention, the polymerization inhibiting agent is further formulated by the composition constituting the resin layer (A), and the halation can be prevented accidentally, and the opening shape can be stabilized and formed. High-precision pattern with deep hardenability and excellent resolution.

[Resin layer (A)] (Basic developing resin composition constituting the resin layer (A))

The alkali-developing resin composition constituting the resin layer (A) is an alkali-soluble resin and a thermally reactive compound which contain one or more functional groups of a phenolic hydroxyl group or a carboxyl group and which can be imaged by an alkali solution. It does not contain the composition of the photopolymerization initiator. The alkali-soluble resin may, for example, be a compound having a phenolic hydroxyl group, a compound having a carboxyl group, or a compound having a phenolic hydroxyl group and a carboxyl group, and a conventionally used one may be used.

In particular, it is a compound containing a carboxyl group, a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin used as a solder resist composition, a compound having an ethylenically unsaturated bond, and thermal reactivity. A compound, and does not contain a resin composition of a photopolymerization initiator.

Here, as a resin containing a carboxyl group, a photosensitive resin containing a carboxyl group, and a compound having an ethylenically unsaturated bond, a conventionally used compound is used, and a cyclic (thio)ether group or the like is used as the thermally reactive compound. A conventionally used compound which hardens the functional group of the reaction by heat.

In the alkali-developing resin composition constituting the resin layer (A), a polymerization inhibiting agent is preferably further prepared. By disposing the polymerization inhibiting agent, the influence of exposure can be minimized, the influence of heat in the PEB step can be suppressed, and the shape of the opening can be stabilized. Moreover, in this case, the problem of deep hardening failure does not occur. Therefore, by adjusting the polymerization inhibitor in the alkali-developing resin composition constituting the resin layer (A), it is possible to achieve both the stability of the opening shape and the excellent deep-curing property.

As the polymerization inhibiting agent, a conventional polymerization inhibitor can be used. Examples of the polymerization inhibiting agent are phenothiazine, hydroquinone, N-phenylnaphthylamine, tetrachlorop-benzoquinone, pyrogallol, benzoquinone, tert-butylcatechol, hydroquinone, methylhydroquinone, Tert-butylhydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, naphthoquinone, 4-methoxy-1-naphthol, 2-hydroxy-1,4-naphthoquinone, with phenol A phosphorus-containing compound of a hydroxyl group, a nitrosamine compound, or the like. These polymerization inhibitors may be used alone or in combination of two or more.

The amount of the polymerization inhibitor is preferably from 0.01 to 100 parts by mass, more preferably from 0.03 to 50 parts by mass, per 100 parts by mass of the alkali-soluble resin. When the amount of the polymerization inhibiting agent is in the above range, it is preferable to prevent halation.

[Resin layer (B)] (Photosensitive thermosetting resin composition constituting the resin layer (B))

The photosensitive thermosetting resin composition constituting the resin layer (B) is an alkali-soluble resin, a photopolymerization initiator, and a heat-reactive compound. As the alkali-soluble resin, the same conventionally used as the resin layer (A) can be used, but the alkali solubility of the quinone ring having excellent properties such as buckling resistance and heat resistance can be preferably used. Resin. Further, as the heat-reactive compound, the same conventional ones as those of the above-mentioned resin layer (A) can be used.

(Alkali-soluble resin with quinone ring)

In the present invention, the alkali-soluble resin having a quinone ring is one having a phenolic hydroxyl group and one or more alkali-soluble groups and a quinone ring. The introduction of the alkali-soluble resin into the quinone ring can be carried out by a conventional method. For example, a resin obtained by reacting a carboxylic anhydride component with an amine component and/or an isocyanate component is exemplified. The ruthenium imidization can be carried out by thermal imidization, or by chemical imidization, and can also be carried out in combination.

Here, the carboxylic anhydride component is exemplified by a tetracarboxylic anhydride or a tricarboxylic anhydride, but is not limited to these anhydrides, and may be a compound having an acid anhydride group and a carboxyl group reactive with an amine group or an isocyanate group. This derivative is used. And these carboxylic anhydride components can be used individually or in combination.

As the amine component, a diamine such as an aliphatic diamine or an aromatic diamine, a polyamine such as an aliphatic polyether amine, a diamine having a carboxylic acid, a diamine having a phenolic hydroxyl group, or the like can be used, but is not limited thereto. Equivalent diamine. And, that The equivalent amine components can be used singly or in combination.

As the isocyanate component, diisocyanate such as aromatic diisocyanate and an isomer thereof or a polymer thereof, an aliphatic diisocyanate, an alicyclic diisocyanate or an isomer thereof, or other widely used diisocyanates can be used. However, it is not limited to the isocyanates. And the isocyanate components can be used singly or in combination.

The alkali-soluble resin having a quinone ring as described above may also have a guanamine bond. These may be those obtained by reacting a quinone imide having a carboxyl group with an isocyanate and a carboxylic acid anhydride, or may be obtained by a reaction other than the above. Further, it may have other addition and condensation bonds.

In the synthesis of an alkali-soluble resin having such an alkali-soluble group and a quinone ring, a conventionally used organic solvent can be used. The organic solvent is a solvent which does not react with a carboxylic anhydride, an amine or an isocyanate of a raw material and can dissolve the raw materials, and is not problematic, and the structure thereof is not limited. In particular, based on the high solubility of the raw material, it is preferably N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl alum An aprotic solvent such as γ-butyrolactone.

The alkali-soluble resin having one or more of a phenolic hydroxyl group and a carboxyl group and an alkali-soluble resin of the quinone ring, as described above, preferably has an acid value of 20 to 200 mgKOH/g in order to correspond to the photolithography step. More preferably, it is 60 to 150 mgKOH/g. When the acid value is 20 mgKOH/g or more, the solubility in alkali is increased, the development property is improved, and the degree of crosslinking between the heat-curing components after light irradiation is improved, so that sufficient development contrast can be obtained. Moreover, when the acid value is 200 mgKOH/g or less, the so-called heat exposure in the PEB (POST EXPOSURE BAKE) step after light irradiation described later can be suppressed, and the process margin can be increased.

Further, the molecular weight of the alkali-soluble resin is preferably from 1,000 to 100,000, more preferably from 2,000 to 50,000, in view of developability and cured film properties. When the molecular weight is 1,000 or more, sufficient development resistance and cured physical properties can be obtained after exposure/PEB. Further, when the molecular weight is 100,000 or less, the alkali solubility is increased and the developability is improved.

(photopolymerization initiator)

The photopolymerization initiator used in the resin layer (B) can be used, for example, a benzoin compound, a phosphonium chloride compound, an acetophenone compound, an α-aminoacetophenone compound, An oxime ester compound, a thioxanthone compound, or the like.

In particular, when it is used in the PEB step after light irradiation described later, it is preferably a photopolymerization initiator which also functions as a photobase generator. Further, in the PEB step, a photopolymerization initiator and a photobase generator may be used in combination.

The photopolymerization initiator which functions as a photobase generator is a polymerizable reaction which is changed by light irradiation such as ultraviolet light or visible light, or is formed by molecular cracking to form a polymerization reaction which is a heat-reactive compound which will be described later. A compound of more than one basic substance that functions as a medium. The basic substance is exemplified by, for example, a secondary amine or a tertiary amine.

As such a photopolymerization initiator which also functions as a photobase generator, for example, an α-aminoacetophenone compound, an oxime ester compound, or An anthracene imino group, an N-methylated aromatic amine group, an N-methylated aromatic amine group, a nitrobenzyl urethane group, a oxybenzyl urethane group a compound such as a substituent of the group. Among them, an oxime ester compound and an α-aminoacetophenone compound are preferred, and an oxime ester compound is more preferred. The α-aminoacetophenone compound is particularly preferably one having two or more nitrogen atoms.

The α-aminoacetophenone compound may be a substance having a benzoin ether bond in the molecule and causing intramolecular cracking upon irradiation with light to form a basic substance (amine) which acts as a hardening catalyst.

As the oxime ester compound, any compound which generates a basic substance by light irradiation can be used.

These photopolymerization initiators may be used alone or in combination of two or more. The amount of the photopolymerization initiator in the resin composition is preferably from 0.1 to 40 parts by mass, more preferably from 0.3 to 20 parts by mass, per 100 parts by mass of the alkali-soluble resin. When the amount is 0.1 part by mass or more, the contrast between the light-irradiating portion and the non-irradiated portion can be improved. When the amount is 40 parts by mass or less, the cured product property is improved.

As the resin composition used in the resin layer (A) and the resin layer (B) described above, the following components can be blended as needed.

(polymer resin)

The polymer resin is formulated for the purpose of improving the flexibility and dryness of the obtained cured product. Examples of such a polymer resin are cellulose-based, polyester-based, phenoxy resin-based polymers, polyvinyl acetal-based, polyvinyl butyral-based, polyamid-based, and polyamidoximine-based adhesives. Agent Polymers, block copolymers, elastomers, and the like. These polymer resins may be used alone or in combination of two or more.

(inorganic filler)

The inorganic filler is formulated to suppress the hardening shrinkage of the cured product and to improve the properties such as adhesion and hardness. As such an inorganic filler, for example, barium sulfate, amorphous ceria, molten ceria, spheroidal ceria, talc, clay, magnesium carbonate, calcium carbonate, alumina, aluminum hydroxide, tantalum nitride , aluminum nitride, boron nitride, Neuburg Siliceous Earth, etc.

(Colorant)

As a coloring agent, a conventionally used coloring agent such as red, blue, green, yellow, white, or black may be used, and any of a pigment, a dye, and a coloring matter may be used.

(Organic solvents)

The organic solvent is formulated to adjust the resin composition or to adjust the viscosity applied to the substrate or the carrier film. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, and the like. These organic solvents may be used singly or in combination of two or more.

(other ingredients)

Further, if necessary, a thiol compound, a adhesion promoter, and an anti-adhesion agent may be formulated. Ingredients such as oxidants and UV absorbers. These can be used by conventional practitioners. Moreover, a conventionally used tackifier such as fine powder of cerium oxide, hydrotalcite, organic bentonite, montmorillonite, or the like, a defoaming agent and/or a leveling agent such as polyfluorene, fluorine or polymer. Conventional additives such as decane coupling agents and rust inhibitors.

Since the laminated structure of the present invention is excellent in buckling property, it can be used for at least one of a bent portion and a non-buckling portion of a flexible printed wiring board, and a cover film for a flexible printed wiring board can be used. At least one of a solder resist and an interlayer insulating material.

The laminated structure of the present invention having the above-described constitution is preferably used as a dry film which is supported or protected by a film on at least one side thereof.

(dry film)

The dry film of the present invention can be produced as follows. That is, first, the composition constituting the resin layer (B) and the resin layer (A) is diluted with an organic solvent to adjust to a moderate viscosity, and according to a conventional method, a conventional method such as a notch applicator is used. It is coated on a carrier film (support film). Subsequently, a dry film formed of the resin layer (B) and the resin layer (A) is formed on the carrier film by drying at a temperature of usually 50 to 130 ° C for 1 to 30 minutes. On the dry film, a peelable cover film (protective film) can be further laminated for the purpose of preventing dust from adhering to the film surface. As the carrier film and the cover film, a conventionally known plastic film can be suitably used. When the cover film is preferably used, the resin film and the carrier film are bonded to each other. Focus on the small. The thickness of the carrier film and the cover film is not particularly limited, and is generally selected in the range of 10 to 150 μm.

(Manufacturing method of wiring board)

The manufacture of the flexible printed wiring board using the laminated structure of the present invention can be carried out in the order shown in the step diagram of Fig. 1. That is, the manufacturing method including the steps of forming the layer of the laminated structure of the present invention on the flexible wiring substrate on which the conductor circuit is formed (layering step), and irradiating the layer of the laminated structure The step of exposing the active energy ray (exposure step), and the step of subjecting the layer of the laminated structure to alkali development to form a layer of the patterned laminated structure at a time (development step). Further, if necessary, after alkali development, photocuring or thermal curing (post-cure step) is carried out to completely cure the layer of the laminated structure, and a highly reliable flexible printed wiring board can be obtained.

Further, the production of the flexible printed wiring board using the laminated structure of the present invention can be carried out in the order shown in the step diagram of Fig. 2 . That is, the manufacturing method including the steps of forming the layer of the laminated structure of the present invention on the flexible wiring substrate on which the conductor circuit is formed (layering step), and irradiating the layer of the laminated structure a step of exposing the active energy ray (exposure step), a step of heating the layer of the laminated structure (heating (PEB) step), and subjecting the layer of the laminated structure to alkali development, and forming a pattern at a time The step of laminating the layers of the structure (development step). Further, if necessary, after alkali development, photohardening or thermal curing (post-cure step) is carried out to completely cure the layer of the laminated structure, and a letter can be obtained. Flexible printed wiring board with high dependence. In particular, when an alkali-soluble resin containing a quinone ring is used for the resin layer (B), the order shown in the step of Fig. 2 is preferably used.

The steps shown in FIG. 1 or FIG. 2 will be described in detail below.

[Lamination step]

This step is performed on the flexible printed wiring board 1 on which the conductor circuit 2 is formed, and a resin layer 3 (resin layer (A)) made of an alkali-developing resin composition containing an alkali-soluble resin or the like is formed. A laminated structure of the resin layer 4 (resin layer (B)) made of a photosensitive thermosetting resin composition containing an alkali-soluble resin or the like on the resin layer 3. Here, each of the resin layers constituting the laminated structure is formed by, for example, applying a resin composition constituting the resin layers 3 and 4 onto the wiring substrate 1 and drying it to form the resin layers 3 and 4, or constituting the resin. The resin composition of the layers 3 and 4 is formed by laminating a dry film form having a two-layer structure on the wiring board 1.

The method of applying the resin composition to the wiring substrate is preferably a conventional method such as a blade coater, a lip coater, a notch coater, or a film coater. Further, the drying method is preferably a method in which a hot air having a heating method using steam is used, such as a hot air circulating drying furnace, an IR furnace, a heating plate, a convection oven, and the like, and a method of bringing the hot air in the dryer into contact with each other and blowing the nozzle A conventional method such as a method of supporting a body.

[Exposure step]

In this step, the photopolymerization initiator contained in the resin layer 4 is activated into a negative pattern by irradiation of the active energy ray to harden the exposed portion. As the exposure machine, a direct drawing device, an exposure machine equipped with a metal halide lamp, or the like can be used. The mask for the exposure of the pattern is a negative mask.

The active energy line used for exposure preferably uses laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm. By setting the maximum wavelength to this range, the photopolymerization initiator can be efficiently activated. Further, the amount of exposure varies depending on the film thickness or the like, but it can be usually set to 100 to 1500 mJ/cm ² .

[PEB step]

This step is to cure the exposed portion by heating the resin layer after exposure. By this step, an exposure step of a resin layer (B) having a photopolymerization initiator as a photobase generator or a combination of a photopolymerization initiator and a photobase generator is used. The base can harden the resin layer (B) to the deep portion. The heating temperature is, for example, 80 to 140 °C. The heating time is, for example, 2 to 140 minutes. The curing of the resin composition in the present invention is caused by, for example, a ring-opening reaction of an epoxy resin which is thermally reacted, so that deformation or hardening shrinkage can be suppressed as compared with the case of curing by photo-radical reaction.

[development step]

In this step, the unexposed portion is removed by alkali development to form a negative-type insulating film, in particular, a cover film and a solder resist. As the developing method, a conventional method such as dipping can be used. Also, as a developing solution, sodium carbonate and carbon can be used. An aqueous solution of potassium salt, potassium hydroxide, an amine, an imidazole such as 2-methylimidazole, an aqueous solution of tetramethylammonium hydroxide (TMAH) or the like, or a mixture thereof.

[Post curing step]

This step is performed after the development step, and the resin layer is completely thermally cured to obtain a highly reliable coating film. The heating temperature is, for example, 140 ° C to 180 ° C. The heating time is, for example, 20 to 120 minutes. Further, light irradiation may be performed before or after post-curing.

[Examples]

Hereinafter, the present invention will be described in more detail by way of the examples and comparative examples, but the invention is not limited by these examples and comparative examples.

<Synthesis Example 1: Synthesis Example of Polyamidoximine Resin Solution>

In a separable 3-necked flask equipped with a stirrer, a nitrogen inlet tube, a fractionation ring, and a cooling ring, 3.8 g of 3,5-diaminobenzoic acid, 2,2'-bis [4-(4) were fed at room temperature. 6.98 g of -aminophenoxy)phenyl]propane, 8.21 g of JEFFAMINE XTJ-542 (manufactured by HUNTSMAN, molecular weight 1025.64), and 86.49 g of γ-butyrolactone were dissolved.

Next, 17.84 g of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride and 2.88 g of trimellitic anhydride were fed and kept at room temperature for 30 minutes. Next, 30 g of toluene was added, the temperature was raised to 160 ° C, and the mixture was stirred for 3 hours while distilling off toluene and water, and then cooled to room temperature to obtain a ruthenium imide solution.

To the obtained quinone imide solution, 9.61 g of trimellitic anhydride and 17.45 g of trimethylhexamethylene diisocyanate were fed, and the mixture was stirred at a temperature of 160 ° C for 32 hours. Thus, a polyamidoquinone imide resin solution (PAI-1) having a carboxyl group was obtained. The acid value of the obtained resin (solid content) was 83.1 mgKOH, and Mw was 4,300.

<Synthesis Example 2: Synthesis of a polyimine resin solution having a quinone ring, a phenolic hydroxyl group, and a carboxyl group>

Add 3,3'-diamino-4,4'-dihydroxydiphenyl fluorene 22.4g, 2,2' to a separable 3-neck flask equipped with a stirrer, a nitrogen inlet tube, a fractionation ring, and a cooling ring. - 8.2 g of bis[4-(4-aminophenoxy)phenyl]propane, 30 g of NMP, 30 g of γ-butyrolactone, 27.9 g of 4,4'-oxydiphthalic anhydride, and 3.8 g of trimellitic anhydride It was stirred at 100 rpm for 4 hours under nitrogen at room temperature. Next, 20 g of toluene was added, and toluene and water were distilled off at a temperature of 180 ° C and 150 rpm for 4 hours to obtain a polyimine resin solution (PI-1) having a phenolic hydroxyl group and a carboxyl group.

The obtained resin (solid content) had an acid value of 18 mgKOH, Mw of 10,000, and a hydroxyl group equivalent of 390.

<Synthesis Example 3: Synthesis of urethane resin containing carboxyl group>

In a reaction vessel equipped with a stirring device, a thermometer, and a condenser, a polycarbonate diol derived from 1,5-pentanediol and 1,6-hexanediol (Take Chemicals Co., Ltd., T5650J, number average) was charged. Molecular weight 800) 2400 g (3 mol), dimethylglycolic acid 603 g (4.5 mol) and 2-hydroxyethyl acrylate as a monohydroxy compound 238 g (2.6 mol). Next, 1887 g (8.5 mol) of isodecyl ketone diisocyanate as a polyisocyanate was charged, and it heated up to 60 degreeC with stirring, and it stopped, and it heated again at the time of the temperature of the reaction container began to fall, and stirring was continued at 80 degreeC, and infrared absorption spectra confirmed that the absorption spectrum of the isocyanate group (2280cm ^-1) disappeared, the reaction was completed. Subsequently, carbitol acetate was added so that the solid content became 50% by mass. The solid content of the obtained carboxyl group-containing resin had an acid value of 50 mgKOH/g.

(Examples 1 to 6 and Comparative Examples 1 to 4)

According to the formulation described in the following table, the materials described in the examples and the comparative examples were prepared, mixed with a mixer, and kneaded in a 3-roll mixer to prepare a resin composition constituting each resin layer. The value in the table is a part by mass of the solid component unless otherwise specified.

<Formation of Resin Layer (A)>

A flexible printed wiring board having a circuit having a copper thickness of 18 μm was prepared, and pretreatment was performed using MECBRITE CB-801Y. Subsequently, each of the resin compositions was applied to the flexible printed wiring board subjected to the pretreatment so that the film thickness after drying was 25 μm. Subsequently, it was dried at 90 ° C / 30 minutes in a hot air circulating drying oven to form a resin layer (A) made of a resin composition.

<Formation of Resin Layer (B)>

Each of the resin compositions was applied to the resin layer (A) formed as described above so that the film thickness after drying was 10 μm. Subsequently, it was dried at 90 ° C / 30 minutes in a hot air circulating drying oven to form a resin layer (B) made of a resin composition.

<sensitivity>

Each of the obtained laminated structures was exposed at 500 mJ/cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp at a step of 41 steps (T-4105 manufactured by STOUFFER). Subsequently, after performing the PEB step of 30 minutes at 90 ° C for Examples 3 to 6 and Comparative Examples 3 and 4, 60 seconds of development (30 ° C, 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) was carried out, and the remaining The number of segments of the step change graph is used as an indicator of sensitivity. The more the number of remaining segments, the better the sensitivity.

<minimum residual line width>

Use of an exposure apparatus equipped with a metal halide lamp (HMW-680-GW20), to 500mJ / cm ² the resultant layers were laminated structure exposed. The exposure pattern uses a negative mask that can expose lines of width 20/30/40/50/60/70/80/90/100 μm. Subsequently, after performing the PEB step of 30 minutes at 90 ° C for Examples 3 to 6 and Comparative Examples 3 and 4, 60 seconds of development (30 ° C, 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) was carried out, and the pattern was drawn. The hardened coating film was obtained by thermal hardening at 150 ° C for 60 minutes. The minimum residual line width of the obtained hardened coating film was counted using an optical microscope adjusted to 200 times. The smaller the minimum residual line width, the better the deep hardenability.

<Flexibility test (mandrel test)>

The obtained laminated structures were exposed at a total temperature of 500 mJ/cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. Subsequently, after performing the PEB step of 30 minutes at 90 ° C for Examples 3 to 6 and Comparative Examples 3 and 4, 60 seconds of development (30 ° C, 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) was carried out by 150 The film was thermally hardened at ° C for 60 minutes to obtain a hardened laminated structure. The obtained hardened laminated structure was cut into about 50 mm × about 200 mm, and the flexurality evaluation was performed using a cylindrical mandrel tester (BYK GARDNER Co., Ltd., No. 5710). The surface of the coating resin composition was placed on the outside, and buckling was performed centering on a mandrel having a diameter of 2 mm, and the presence or absence of discoloration or cracking was evaluated. When the buckling portion was not discolored or cracked, it was marked as ◎, and when it was discolored, the crack was not observed when it was cracked, and when it was cracked, it was marked as ×.

<heat resistance test>

A negative type mask having an opening of about 2 mm to 5 mm in diameter was formed on the copper by using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and each of the obtained laminated structures was exposed at 500 mJ/cm ² . Subsequently, after performing the PEB step of 30 minutes at 90 ° C for Examples 3 to 6 and Comparative Examples 3 and 4, 60 seconds of development (30 ° C, 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) was carried out by 150 The film was thermally hardened at ° C for 60 minutes to obtain a hardened laminated structure. The obtained hardened laminated structure was immersed in a solder bath heated to 260 ° C and 280 ° C to conduct a heat resistance test. The surface of the coating resin composition was brought into contact with the solder for 5 seconds, and then recovered and cooled, and the presence or absence of the bulging and peeling of the resin composition was evaluated. When bulging or peeling occurred at 280 ° C, it was marked as ◎, and bulging and peeling did not occur at 260 ° C. When bulging and peeling occurred at 280 ° C, it was marked as ○, and when 260 ° C was raised and peeled off, it was marked as ×.

The evaluation results are shown together in the table below.

*2) PAI-1: Polyamidoximine imide resin of Synthesis Example 1.

*3) PI-1: Polyimine resin of Synthesis Example 2

*4) BPE-900: Epoxidized bisphenol A dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.)

*5) E1001: bisphenol A type epoxy resin, epoxy equivalent 450~500 (Mitsubishi Chemical Co., Ltd.)

*6) E834: bisphenol A type epoxy resin, epoxy equivalent 230~270 (Mitsubishi Chemical Co., Ltd.)

*7) IRGACURE OXE02: Lanthanide photopolymerization initiator (manufactured by BASF Corporation)

*8) IRGACURE 379: Phenyl ketone photopolymerization initiator (manufactured by BASF Corporation)

*9) Carboxyl group-containing urethane resin: resin of Synthesis Example 3

*10) E828: bisphenol A type epoxy resin, epoxy equivalent 190, mass average molecular weight 380 (Mitsubishi Chemical Co., Ltd.)

As can be seen from the evaluation results shown in the above table, the laminated structure of each of the examples was excellent in sensitivity and excellent in deep hardenability as compared with the laminated structure of each comparative example. On the other hand, in each of the comparative examples of the photopolymerization initiator containing the resin layer (A), the photopolymerization initiator absorbs light, and deep curing property cannot be obtained, and the fine lines fall off during development.

(Examples 7 to 12, Comparative Example 5)

According to the formulation described in the following table, the materials described in the examples and the comparative examples were prepared, and the mixture was prepared by a mixer, and then kneaded in a 3-roll mixer to prepare a resin composition constituting each resin layer, which was the same as in the first embodiment and the like. The formation of the resin layer (A) and the resin layer (B) is carried out. The value in the table is a part by mass of the solid component unless otherwise specified.

<Resolution (opening size and minimum residual line width)>

Each of the obtained laminated structures was exposed at 500 mJ/cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. The exposure pattern uses a pattern depicting a line having a width of 30/40/50/60/70/80/90/100 μm and a pattern having an opening of 300 μm. Subsequently, after performing a PEB step of 30 minutes at 90 ° C, 60 seconds of development (30 ° C, 0.2 MPa, 1 mass % Na ₂ CO ₃ aqueous solution) was carried out, and a pattern was drawn, which was obtained by heat hardening at 150 ° C for 60 minutes. Hardened film. With respect to the obtained cured coating film, the minimum residual line width was counted using an optical microscope adjusted to 200 times, the opening size (design value 300 μm) was measured, and the shape of the opening was taken. The smaller the minimum residual line width, the better the deep hardenability. The results are shown in the table below and in Figures 3(a) to (i).

<Chemical resistance (resistance to electroless gold plating)>

The hardened coating film on the above-mentioned substrate was plated under the conditions of 0.5 μm of nickel and 0.03 μm of gold using a commercially available electroless gold plating bath, and the plated evaluation substrate was evaluated for the presence or absence of plating penetration, and the tape was used. The peeling evaluation of the resist layer was carried out without peeling. The judgment criteria are as follows. The results obtained are shown in the table below.

○: No penetration or peeling was observed.

△: A little penetration was observed after plating, but no peeling was observed after the tape was peeled off.

×: Peeling was observed after the tape was peeled off.

*12) QS-30: 4-methoxy-1-naphthol (Kawasaki Chemical Industry Co., Ltd.)

*13) HCA-HQ: Phosphorus compound containing phenolic hydroxyl group (made by Sanguang Co., Ltd.)

In the laminated structures of Examples 7 to 12 in which the polymerization inhibiting agent was blended in the resin layer (A), the haze was small and the opening shape was stable, and the minimum residual line width was also 30 μm. On the other hand, in Example 6, which was prepared in the same manner as in Example 12 except for the unaltered polymerization inhibiting agent, the opening size and the gold plating resistance were evaluated, and the minimum residual line width was 30 μm, which was good, but there was a halo and an opening size. It is slightly smaller than 240 μm. Further, in Comparative Example 5, a photopolymerization initiator was used for the resin layer (A), and although a halo was prevented to some extent, the gold plating resistance was poor, and the minimum line width and the opening size were not sufficient.

1‧‧‧Flexible printed wiring board

2‧‧‧Conductor circuit

3‧‧‧ resin layer

4‧‧‧ resin layer

5‧‧‧ mask

Claims (6)

A laminated structure comprising a resin layer (A) and a resin layer (B) laminated on the flexible printed wiring board via the resin layer (A), characterized by the resin layer (B) is a photosensitive thermosetting resin composition containing an alkali-soluble resin, a photopolymerization initiator, and a heat-reactive compound, and the resin layer (A) is thermally reacted with an alkali-soluble resin. The compound is a composition of an alkali-developing resin composition which does not contain a photopolymerization initiator. The laminated structure according to claim 1, wherein the resin layer (A) is further composed of a resin composition containing a polymerization inhibiting agent. The laminated structure of claim 1, which is at least one of a bent portion and a non-buckled portion used in the flexible printed wiring board. The laminated structure of claim 1, which is used for at least one of a cover film, a solder resist, and an interlayer insulating material for a flexible printed wiring board. A dry film characterized in that at least one side of the laminated structure of claim 1 is supported or protected by a film. A flexible printed wiring board characterized by having an insulating film formed on a flexible printed wiring board as a layer of the laminated structure of claim 1 and patterned by light irradiation. It is formed by the formation of a pattern once in the liquid.