KR101998002B1 - Laminate structure, dry film, and flexible printed wiring board - Google Patents

Abstract

(EN) Provided is a flexible printed wiring board excellent in flexibility and suitable for a process for collectively forming an insulating film of a flexible printed wiring board, in particular, a bending part (bending part) and a mounting part (non - bending part), and a dry film and a cured product thereof as a protective film. A resin layer (A) and a resin layer (B) laminated on the flexible printed wiring board via the resin layer (A). Wherein the resin layer (B) comprises a photosensitive thermosetting resin composition comprising an alkali soluble resin, a photopolymerization initiator and a thermoreactive compound, and the resin layer (A) contains an alkali soluble resin and a thermoreactive compound and contains a photopolymerization initiator And the like.

Description

A laminated structure, a dry film, and a flexible printed wiring board (LAMINATE STRUCTURE, DRY FILM, AND FLEXIBLE PRINTED WIRING BOARD)

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

2. Description of the Related Art [0002] In recent years, miniaturization of electronic devices due to the spread of smart phones and tablet terminals has necessitated a smaller space for circuit boards. As a result, the use of a flexible printed wiring board that can be folded and stored has been expanded, and a flexible printed wiring board has been required to have higher reliability than ever.

On the other hand, as the insulating film for securing the insulation reliability of the flexible printed wiring board at present, a coverlay based on polyimide having excellent mechanical properties such as heat resistance and bending property is used as the bent portion (bent portion) A mixed process using a photosensitive resin composition which is excellent in electrical insulation and solder heat resistance and can be microfabricated is widely adopted as a mounting portion (non-bending portion).

That is, the coverlay based on polyimide is not suitable for fine wiring because it requires machining by die punching. Therefore, it is necessary to partially use an alkali development type photosensitive resin composition (solder resist) capable of being processed by photolithography in the chip mounting portion where fine wiring is required.

Japanese Patent Application Laid-Open No. 62-263692 Japanese Patent Application Laid-Open No. 63-110224

As described above, in the manufacturing process of the conventional flexible printed wiring board, there is a problem that cost and operability are deteriorated because a process of attaching the coverlay and a process of forming the solder resist must be employed.

On the contrary, conventionally, it has been studied to apply an insulating film as a solder resist or an insulating film as a coverlay as a solder resist and a coverlay of a flexible printed wiring board. However, a material satisfying both required performance has not yet been put to practical use.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a laminated structure having excellent flexibility and suitable for a process for collectively forming an insulating film of a flexible printed wiring board, in particular, a bending part (bending part) and a mounting part To provide a flexible printed wiring board having a coverlay or a solder resist.

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have completed the present invention.

That is, the laminated structure of the present invention is a laminated structure having a resin layer (A) and a resin layer (B) laminated on the flexible printed wiring board via the resin layer (A), wherein the resin layer (B) A photosensitive thermosetting resin composition comprising an alkali-soluble resin, a photopolymerization initiator and a thermoreactive compound, wherein the resin layer (A) comprises an alkali-soluble type resin containing an alkali-soluble resin and a thermoreactive compound and not containing a photopolymerization initiator And a resin composition.

In the laminated structure of the present invention, it is preferable that the resin layer (A) includes a resin composition further comprising a polymerization inhibitor.

The laminated structure of the present invention can be used for at least one of the bent portion and the non-bent portion of the flexible printed wiring board and can be used for at least any of the coverlay, the solder resist and the interlayer insulating material of the flexible printed wiring board.

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.

The flexible printed wiring board of the present invention is characterized by having an insulating film formed by forming a layer of the laminated structure of the present invention on a flexible printed wiring board, patterning the same by light irradiation, and collecting patterns in a developer .

Here, in the flexible printed wiring board of the present invention, the resin layer (A) and the resin layer (B) are sequentially formed without using the laminate structure according to the present invention, and then patterned by light irradiation, The patterns may be collectively formed. In the present invention, the term " pattern " means a patterned cured product, that is, an insulating film.

According to the present invention, it is possible to provide a multilayer structure excellent in flexibility and suitable for a process for collectively forming an insulating film of a flexible printed wiring board, in particular, a bending part (bending part) and a mounting part (non-bending part), a dry film and a cured product thereof, It is possible to realize a flexible printed wiring board having a coverlay or a solder resist.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a process diagram schematically showing an example of a manufacturing method of a flexible printed wiring board according to the present invention. FIG.
2 is a process diagram schematically showing another example of the manufacturing method of the flexible printed wiring board of the present invention.
3 is a photograph showing an opening shape obtained in the embodiment.

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

(Laminated structure)

The laminated structure of the present invention comprises a resin layer (A) and a resin layer (B) laminated on the flexible printed wiring board via the resin layer (A), wherein the resin layer (B) comprises an alkali- And a photosensitive thermosetting resin composition comprising a thermosetting resin and a thermosetting resin composition, wherein the resin layer (A) contains an alkali-soluble resin and a heat-reactive compound and does not contain a photopolymerization initiator.

The laminated structure of the present invention has a resin layer (A) and a resin layer (B) in this order on a flexible printed wiring board on which a copper circuit is formed on a flexible substrate and the resin layer (B) And the resin layer (B) and the resin layer (A) can collectively form a pattern by development.

In the laminated structure of the present invention, since the resin layer (A) on the printed wiring board side does not contain a photopolymerization initiator, it can not be patterned as a single layer, but when exposed, The active species such as radicals generated from the photopolymerization initiator diffuse into the resin layer (A) immediately below, so that both layers can be patterned at the same time. Particularly, in the method for producing a printed wiring board including a POST EXPOSURE BAKE (PEB) process, the effect is remarkable due to thermal diffusion of the active species.

On the other hand, when the photopolymerization initiator is contained in the resin layer (A) on the printed wiring board side, since the photopolymerization initiator itself has a property of absorbing light, the ability to initiate polymerization of the photopolymerization initiator decreases toward the core part, It is difficult to form a high-precision pattern. However, due to the influence of the diffusion of the active species from the resin layer (B) in the upper layer in the laminated structure of the present invention, The inventors thought that the problem could also be improved. However, in spite of the diffusion of the active species, there is still a problem that the photoreactivity (deep curability) of the deep portion is still poor due to the interaction with the photopolymerization initiator, resulting in undercut.

Therefore, in the structure of the laminated structure of the present invention, it is necessary that the resin layer (A) does not contain a photopolymerization initiator, and as a result, it becomes possible to form a pattern with excellent deep portion curability without undercut.

In the laminated structure according to the present invention, the reason is not clear. However, since diffusion of the active species occurs due to the influence of the interface other than in the exposed portion, There arises a new problem that a so-called halftoning is apt to occur in the vicinity of the interface of the resin layer (B). This problem was particularly noticeable in the PEB process. In this respect, in the laminated structure of the present invention, by further adding a polymerization inhibitor to the composition constituting the resin layer (A), it is possible to prevent illegally from unexpectedly, to stabilize the opening shape and to achieve good deep- It becomes possible to form a high-precision pattern having excellent resolution.

[Resin Layer (A)]

(Alkali-developable resin composition constituting the resin layer (A)),

Examples of the alkali-developing resin composition constituting the resin layer (A) include an alkali-soluble resin containing at least one functional group selected from the group consisting of a phenolic hydroxyl group and a carboxyl group, capable of being developed into an alkali solution, and a thermoreactive compound, The composition may be any composition. As the alkali-soluble resin, for example, a compound having a phenolic hydroxyl group, a compound having a carboxyl group, a compound having a phenolic hydroxyl group and a carboxyl group can be used, and known ones are used.

Particularly a resin containing a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin which has been conventionally used as a solder resist composition and a compound having an ethylenically unsaturated bond and a thermoreactive compound and which contains a compound having a carboxyl group and does not contain a photopolymerization initiator Composition.

Here, as a compound having a carboxyl group-containing resin or a carboxyl group-containing photosensitive resin and a compound having an ethylenically unsaturated bond, a known compound is used, and as the heat-reactive compound, a compound having a functional group capable of curing reaction by heat such as a cyclic (thio) A compound for known purpose is used.

It is preferable to add a polymerization inhibitor to the alkali-developing resin composition constituting the resin layer (A). By combining the polymerization inhibitor, the influence of exposure can be minimized, the influence of heat in the PEB process can be suppressed, and the opening shape can be stabilized. In this case, there is also no problem of poor curing in the core portion. Therefore, by incorporating a polymerization inhibitor into the alkali-developing resin composition constituting the resin layer (A), stabilization of the opening shape and good deep-part curability can be achieved.

As the polymerization inhibitor, a known polymerization inhibitor may be used. Examples of the polymerization inhibitor include phenothiazine, hydroquinone, N-phenylnaphthylamine, chloriranyl, pyrogallol, benzoquinone, t-butylcatechol, hydroquinone, methylhydroquinone, tert- butylhydroquinone, hydroquinone monomethyl Ether, catechol, pyrogallol, naphthoquinone, 4-methoxy-1-naphthol, 2-hydroxy 1,4-naphthoquinone, phosphorus containing compounds having a phenolic hydroxyl group, have. These polymerization inhibitors may be used alone or in combination of two or more.

The blending amount of the polymerization inhibitor is preferably 0.01 to 100 parts by mass, more preferably 0.03 to 50 parts by mass, based on 100 parts by mass of the alkali-soluble resin. When the blending amount of the polymerization inhibitor is within the above range, it is possible to prevent halation, which is preferable.

[Resin Layer (B)]

(Photosensitive thermosetting resin composition constituting the resin layer (B)).

The photosensitive thermosetting resin composition constituting the resin layer (B) comprises an alkali-soluble resin, a photopolymerization initiator, and a heat-reactive compound. Among them, known alkali-soluble resins similar to those of the resin layer (A) can be used as the alkali-soluble resin, but an alkali-soluble resin having an imide ring excellent in flex resistance and heat resistance can be suitably used. As the heat-reactive compound, a known publicly known compound similar to the resin layer (A) can be used.

(An alkali-soluble resin having an imide ring)

In the present invention, the alkali-soluble resin having an imide ring is one having at least one alkali-soluble group in the phenolic hydroxyl group and the carboxyl group and an imide ring. For the introduction of the imide ring into the alkali soluble resin, a publicly known method can be used. For example, a resin obtained by reacting a carboxylic acid anhydride component with an amine component and / or an isocyanate component can be given. The imidization may be performed by heat imidization, chemical imidization, or both.

Examples of the carboxylic acid anhydride component include tetracarboxylic acid anhydride and tricarboxylic acid anhydride. However, the carboxylic anhydride component is not limited to these acid anhydrides but may be a compound having an acid anhydride group and a carboxyl group which react with an amino group or an isocyanate group , A derivative thereof can be used. These carboxylic acid anhydride components may be used alone or in combination.

Examples of the amine component include diamines such as aliphatic diamines and aromatic diamines, polyamines such as aliphatic polyether amines, diamines having carboxylic acids, and diamines having phenolic hydroxyl groups, but the amines are not limited to these amines. These amine components may be used alone or in combination.

As the isocyanate component, diisocyanates such as aromatic diisocyanates and isomers or isomers thereof, aliphatic diisocyanates, alicyclic diisocyanates and isomers thereof, and other commonly used diisocyanates can be used. However, the diisocyanates are not limited to these isocyanates It is not. These isocyanate components may be used alone or in combination.

The alkali-soluble resin having an imide ring as described above may have an amide bond. This may be a polyamideimide obtained by reacting an imide compound having a carboxyl group with an isocyanate and a carboxylic acid anhydride or may be obtained by other reactions. And may have a bond including addition and condensation.

In the synthesis of such an alkali-soluble resin having an alkali-soluble group and an imide ring, a known organic solvent may be used. Such an organic solvent is not particularly limited as long as it does not react with carboxylic acid anhydrides, amines and isocyanates as starting materials, and is a solvent in which these raw materials are dissolved, and its structure is not particularly limited. Particularly, from the viewpoint of high solubility of the starting materials, non-protonic substances such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylsulfoxide, Solvents are preferred.

The alkali soluble resin having at least one alkali soluble group and imide ring in the phenolic hydroxyl group or carboxyl group as described above preferably has an acid value of 20 to 200 mgKOH / g in order to cope with the photolithography step, It is preferably 60 to 150 mg KOH / g. When the acid value is 20 mgKOH / g or more, the solubility in alkali increases, the developability becomes good, and further the degree of crosslinking with the thermosetting component after the light irradiation becomes high, so that sufficient development contrast can be obtained. Further, when the acid value is 200 mgKOH / g or less, so-called heat shielding in the post-exposure bake (PEB) process after light irradiation described later can be suppressed, and the process margin is increased.

The molecular weight of the alkali-soluble resin is preferably 1,000 to 100,000, more preferably 2,000 to 50,000, in view of the developability and the cured coating film characteristics. When the molecular weight is 1,000 or more, sufficient developability and curing properties can be obtained after exposure and PEB. When the molecular weight is 100,000 or less, the alkali solubility is increased and the developability is improved.

(Photopolymerization initiator)

As the photopolymerization initiator used in the resin layer (B), known ones can be used, and examples thereof include benzoin compounds, acylphosphine oxide compounds, acetophenone compounds,? -Amino acetophenone compounds, oxime ester compounds , Thioxanthone compounds, and the like.

Particularly, when used in a PEB process after light irradiation described below, a photopolymerization initiator having a function as a photobase generator is also suitable. Further, in this PEB step, a photopolymerization initiator and a photobase generator may be used in combination.

The photopolymerization initiator having a function as a photobase generator may be one or more kinds of photopolymerization initiators which can function as a catalyst for the polymerization reaction of a thermoreactive compound which will be described later when the molecular structure is changed by irradiation of light such as ultraviolet rays or visible light, It is a compound that produces a basic substance. As the basic substance, for example, secondary amine and tertiary amine can be mentioned.

Examples of the photopolymerization initiator having a function as a photobase generator include, for example, an? -Aminoacetophenone compound, an oxime ester compound, an acyloxyimino group, an N-formylated aromatic amino group, a N-acylated aromatic amino group, A compound having a substituent such as a benzoate, an alkoxybenzylcarbamate group and the like. Of these, oxime ester compounds and? -Aminoacetophenone compounds are preferable, and oxime ester compounds are more preferable. As the? -amino acetophenone compound, it is particularly preferable to have two or more nitrogen atoms.

The? -amino acetophenone compound may be any one that has a benzoin ether bond in its molecule and undergoes cleavage in the molecule upon irradiation with light to generate a basic substance (amine) which exerts a curing catalytic action.

As the oxime ester compound, any compound capable of generating a basic substance by light irradiation can be used.

One such photopolymerization initiator may be used alone, or two or more photopolymerization initiators may be used in combination. The blending amount of the photopolymerization initiator in the resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.3 to 20 parts by mass, based on 100 parts by mass of the alkali soluble resin. When the amount is not less than 0.1 part by mass, the contrast of the developability of the light irradiation portion / the non-irradiation portion can be satisfactorily obtained. When the amount is 40 parts by mass or less, the properties of the cured product are improved.

The resin composition used in the resin layer (A) and the resin layer (B) as described above may contain the following components, if necessary.

(Polymer resin)

For the purpose of improving the flexibility and tack-and-dryness of the resulting cured product, a publicly known one can be blended with the polymer resin. Examples of such a polymer resin include cellulose type, polyester type, phenoxy resin type, polyvinyl acetal type, polyvinyl butyral type, polyamide type, polyamideimide type binder polymer, block copolymer and elastomer. These polymer resins may be used alone or in combination of two or more.

(Inorganic filler)

The inorganic filler can be compounded in order to suppress curing shrinkage of the cured product and improve the properties such as adhesion and hardness. Examples of the inorganic filler include barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, silicon nitride, aluminum nitride, And the like.

(coloring agent)

As the coloring agent, known coloring agents such as red, blue, green, yellow, white, and black can be mixed, and any of pigments, dyes, and pigments may be used.

(Organic solvent)

The organic solvent may be blended for the production of a resin composition or for viscosity adjustment 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, petroleum solvents and the like. These organic solvents may be used singly or as a mixture of two or more kinds.

(Other components)

If necessary, components such as a mercapto compound, an adhesion promoter, an antioxidant, and an ultraviolet absorber may be blended. These can be used for known purposes. It is also possible to add known additives such as thickening agents for known additives such as fine silica, hydrotalcite, organic bentonite and montmorillonite, antifoaming agents such as silicone, fluorine and high molecular weight and / or leveling agents, silane coupling agents and rust preventive agents .

The laminated structure of the present invention can be used for at least one of the bent portion and the non-bent portion of the flexible printed wiring board in view of excellent flexibility and can be used for at least any one of the coverlay, the solder resist and the interlayer insulating material of the flexible printed wiring board .

It is preferable that the laminated structure of the present invention constructed as described above is used as a dry film in which at least one side thereof is supported or protected by a film.

(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 on the carrier film (support film) and adjusted to an appropriate viscosity, and a known composition such as a comma coater Method. Then, the dry film containing the resin layer (B) and the resin layer (A) can be formed on the carrier film by usually drying at a temperature of 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 the adherence of dust to the surface of the film. As the carrier film and the cover film, conventionally known plastic films can be suitably used. For the cover film, it is preferable that the cover film is smaller than the adhesive force between the resin layer and the carrier film. The thickness of the carrier film and the cover film is not particularly limited, but is generally appropriately selected in the range of 10 to 150 mu m.

(Manufacturing method of wiring board)

The production of the flexible printed wiring board using the laminated structure of the present invention can be performed according to the procedure shown in the process chart of Fig. That is, a step (lamination step) of forming a layer of the laminated structure of the present invention on a flexible wiring board on which a conductor circuit is formed, a step of irradiating the layer of the laminated structure with a pattern of active energy rays (exposure step) And a step of collectively forming layers of the patterned laminated structure by developing the layer of the structure with an alkali (developing step). Further, after the alkaline development, if necessary, further light curing or thermosetting (post-curing step) is carried out to completely cure the layer of the laminated structure, whereby a highly reliable flexible printed wiring board can be obtained.

The production of the flexible printed wiring board using the laminated structure of the present invention can also be performed according to the procedure shown in the process chart of Fig. That is, a step (lamination step) of forming a layer of the laminated structure of the present invention on a flexible wiring board on which a conductor circuit is formed, a step of irradiating the layer of the laminated structure with a pattern of active energy rays (exposure step) A step of heating a layer of the structure (a heating (PEB) step), and a step of alkali-developing the layer of the laminated structure to collectively form the layers of the patterned laminated structure (developing step). If necessary, after the alkali development, further light curing or thermosetting (post-curing step) is carried out to completely cure the layer of the laminated structure, whereby a highly reliable flexible printed wiring board can be obtained. Particularly, in the case where an imide ring-containing alkali-soluble resin is used in the resin layer (B), it is preferable to use the procedure shown in the process chart of Fig.

Hereinafter, each step shown in Fig. 1 or Fig. 2 will be described in detail.

[Lamination step]

In this step, a resin layer 3 (resin layer (A)) containing an alkali developing resin composition containing an alkali soluble resin or the like and a resin layer And a resin layer 4 (resin layer (B)) containing a photosensitive thermosetting resin composition containing an alkali soluble resin or the like on the paper layer 3 is formed. Here, the respective resin layers constituting the laminated structure are formed by forming resin layers 3 and 4 by, for example, applying the resin composition constituting the resin layers 3 and 4 sequentially to the wiring substrate 1 and drying the same Alternatively, the resin composition constituting the resin layers 3 and 4 may be formed in the form of a two-layered dry film by a method of laminating the resin composition on the wiring board 1.

The method of applying the resin composition to the wiring board may be a known method such as a blade coater, a lip coater, a comma coater, and a film coater. The drying method includes a method in which warm air in a dryer is countercurrently contacted using a hot air circulating drying furnace, IR, a hot plate, a convection oven, or the like, Or a known method such as a spraying method.

[Exposure step]

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

As the active energy ray used for exposure, laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm is preferably used. By setting the maximum wavelength within this range, the photopolymerization initiator can be activated efficiently. The exposure dose varies depending on the film thickness and the like, but it may be usually from 100 to 1500 mJ / cm 2.

[PEB process]

In this step, after exposure, the resin layer is heated to cure the exposed portion. By this step, a photopolymerization initiator having a function as a photopolymerization initiator can be used, or a base generated in the exposure step of the resin layer (B) including a composition comprising a photopolymerization initiator and a photo- B) to the core. The heating temperature is, for example, 80 to 140 占 폚. The heating time is, for example, 2 to 140 minutes. The curing of the resin composition in the present invention is a ring-opening reaction of an epoxy resin by, for example, a thermal reaction, so that deformation and curing shrinkage can be suppressed as compared with the case where curing proceeds by a photo radical reaction.

[Development process]

In this step, the unexposed portion is removed by alkali development to form a negative patterned insulating film, in particular, a coverlay and a solder resist. As the developing method, a known method such as dipping can be used. As the developing solution, an aqueous alkali solution such as sodium carbonate, potassium carbonate, potassium hydroxide, amines, imidazoles such as 2-methylimidazole, aqueous solution of tetramethylammonium hydroxide (TMAH), or a mixture thereof can be used.

[Post-curing process]

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

Example

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

≪ Synthesis Example 1: Synthesis Example of Polyamideimide Resin Solution >

Diaminobenzoic acid and 3.8 g of 2,2'-bis [4- (4-aminophenoxy) phenyl] propane were placed in a separable three-necked flask equipped with a stirrer, 6.98 g of propane, 8.21 g of Zephamin XTJ-542 (manufactured by Huntsman, molecular weight 1025.64) and 86.49 g of? -Butyrolactone were dissolved at room temperature.

Subsequently, 17.84 g of cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride and 2.88 g of trimellitic anhydride were added and kept at room temperature for 30 minutes. Subsequently, 30 g of toluene was added, the temperature was raised to 160 캜, and toluene and water were distilled off while stirring for 3 hours, followed by cooling to room temperature to obtain an imide frement solution.

9.61 g of trimellitic anhydride and 17.45 g of trimethylhexamethylene diisocyanate were added to the obtained imide cargo solution, and the mixture was stirred at a temperature of 160 캜 for 32 hours. Thus, a polyamide-imide resin solution (PAI-1) having a carboxyl group was obtained. The obtained resin (solid content) had an acid value of 83.1 mgKOH and an Mw of 4300.

Synthesis Example 2: Synthesis of polyimide resin solution having imide ring, phenolic hydroxyl group and carboxyl group>

In a separable three-necked flask equipped with a stirrer, a nitrogen introducing tube, a separating ring and a cooling ring, 22.4 g of 3,3'-diamino-4,4'-dihydroxydiphenyl sulfone, 8.2 g of 4- (4-aminophenoxy) phenyl] propane, 30 g of NMP, 30 g of? -Butyrolactone, 27.9 g of 4,4'-oxydiphthalic anhydride and 3.8 g of trimellitic anhydride , And the mixture was stirred at 100 rpm for 4 hours at room temperature under a nitrogen atmosphere. Subsequently, 20 g of toluene was added, and the mixture was stirred for 4 hours while distilling off toluene and water at a silicon bath temperature of 180 캜 at 150 rpm to obtain a polyimide 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, an Mw of 10,000 and a hydroxyl group equivalent of 390.

≪ Synthesis Example 3: Synthesis of carboxyl group-containing urethane resin &

Polycarbonate diol (T5650J, manufactured by Asahi Kasei Chemicals Co., Ltd., number average molecular weight 800 (produced by Asahi Kasei Chemicals Co., Ltd.), 1,5-pentanediol and 1,6-hexanediol were charged in a reaction vessel equipped with a stirrer, a thermometer and a condenser. ), 603 g (4.5 mol) of dimethylolpropionic acid and 238 g (2.6 mol) of 2-hydroxyethyl acrylate as a monohydroxyl compound were introduced. Subsequently, 1887 g (8.5 mol) of isophorone diisocyanate was added as polyisocyanate, and the mixture was heated to 60 DEG C with stirring and stopped. When the temperature in the reaction vessel began to decrease, the mixture was heated again and stirring was continued at 80 DEG C, The absorption spectrum (2280 cm ^-1 ) of the isocyanate group was confirmed to be lost in the infrared absorption spectrum, and the reaction was terminated. Thereafter, carbitol acetate was added so that the solid content was 50 mass%. The solid content of the obtained carboxyl group-containing resin was 50 mgKOH / g.

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

The materials described in the examples and the comparative examples were each compounded, premixed with a stirrer, and kneaded with a three-roll mill to prepare a resin composition constituting each resin layer. The values in the table are parts by mass of solids, unless otherwise noted.

≪ Formation of Resin Layer (A) >

A flexible printed wiring board on which a circuit with a copper thickness of 18 mu m was formed was prepared and preprocessed using Macblight CB-801Y. Thereafter, each of the resin compositions was coated on the preprinted flexible printed wiring board so that the film thickness after drying was 25 mu m. Thereafter, the resultant was dried with a hot-air circulation type drying furnace at 90 DEG C for 30 minutes to form a resin layer (A) containing the resin composition.

≪ Formation of resin layer (B) >

Each of the resin compositions was coated on the resin layer (A) formed as described above so as to have a thickness of 10 mu m after drying. Thereafter, the resultant was dried at 90 DEG C for 30 minutes in a hot-air circulation type drying furnace to form a resin layer (B) containing the resin composition.

<Sensitivity>

Each of the obtained laminated structures was exposed at 500 mJ / cm 2 through a 41-step step tablet (STOUFFER T-4105) using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. Then, Examples 3 to 6 and Comparative Example 3, and then carried out for 30 minutes at 90 ℃ PEB step for 4 to 60 seconds, the developer (30 ℃, 0.2㎫, 1 wt% Na ₂ CO ₃ solution) is performed, the remaining The step number of the step tablet was made an index of the sensitivity. The higher the number of the remaining stages, the better the sensitivity.

&Lt; Minimum remaining line width &

Each laminated structure thus obtained was exposed at 500 mJ / cm 2 using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. A negative mask for exposing a line having a width of 20/30/40/50/60/70/80/90/100 μm was used as the exposure pattern. Then, Examples 3 to 6 and Comparative Example 3, and then carried out for 30 minutes at 90 ℃ PEB step for 4 subjected to the development (30 ℃, 0.2㎫, 1 wt% Na ₂ CO ₃ solution) to 60 seconds, the pattern Then, the cured coating film was obtained by thermosetting at 150 占 폚 for 60 minutes. The minimum remaining line width of the obtained cured coating film was counted using an optical microscope adjusted to 200 times. The smaller the minimum remaining line width is, the better the deep curing property is.

<Flexibility test (mandrel test)>

Each of the obtained laminated structure bodies was entirely exposed at 500 mJ / cm 2 using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. Then, Examples 3 to 6 and Comparative Example 3, and then carried out for 30 minutes at 90 ℃ PEB step for 4, subjected to developing for 60 seconds (30 ℃, 0.2㎫, 1 wt% Na ₂ CO ₃ aqueous solution), 150 C for 60 minutes to obtain a cured laminated structure. The obtained cured laminated structure was cut to a size of about 50 mm x about 200 mm, and flexural properties were evaluated using a cylindrical mandrel tester (BYK Gardner Co., Ltd., No. 5710). The surface coated with the resin composition was placed on the outside and bent around a central rod having a diameter of 2 mm to evaluate discoloration and occurrence of cracks. The case where there was no discoloration or crack in the bent portion was rated as?, A case in which there was discoloration, no crack occurred, and a case where crack occurred.

<Heat resistance test>

Each of the obtained laminated structures was exposed at 500 mJ / cm 2 through a negative mask having openings of about 2 mm to 5 mm in diameter formed on copper using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. Then, Examples 3 to 6 and Comparative Example 3, and then carried out for 30 minutes at 90 ℃ PEB step for 4, subjected to developing for 60 seconds (30 ℃, 0.2㎫, 1 wt% Na ₂ CO ₃ aqueous solution), 150 C for 60 minutes to obtain a cured laminated structure. The obtained cured laminated structure was immersed in a solder tank heated to 260 占 폚 and 280 占 폚 to carry out a heat resistance test. The surface coated with the resin composition was allowed to stand in the bath for 5 seconds so as to come in contact with the solder, and then recovered and cooled to evaluate the occurrence of lifting and peeling of the resin composition. And when the peeling occurred at 280 占 폚, no peeling occurred. The peeling occurred at 260 占 폚. No peeling occurred. The peeling occurred at 280 占 폚. When peeling occurred, the peeling occurred at 260 占 폚. .

The evaluation results are all shown in the following table.

* 1) ZFR-1401H: acid-modified bisphenol F type epoxy acrylate, acid value 98 mgKOH / g (manufactured by Nippon Kayaku Co., Ltd.)

* 2) PAI-1: Polyamideimide resin of Synthesis Example 1

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

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

* 5) E1001: bisphenol A type epoxy resin, epoxy equivalent 450 to 500 (manufactured by Mitsubishi Chemical Corporation)

* 6) E834: bisphenol A type epoxy resin, epoxy equivalent 230 to 270 (manufactured by Mitsubishi Chemical Corporation)

* 7) IRGACURE OXE02: Oxime photopolymerization initiator (BASF)

* 8) IRGACURE 379: alkylphenon-based photopolymerization initiator (BASF)

* 9) urethane resin containing carboxyl group: Resin of Synthesis Example 3

* 10) E828: bisphenol A type epoxy resin, epoxy equivalent 190, mass average molecular weight 380 (manufactured by Mitsubishi Chemical Corporation)

As is evident from the evaluation results shown in the above table, it is clear that the laminated structures of the respective Examples are superior in sensitivity as well as deep-part curing property as compared with the laminated structures of the respective Comparative Examples. On the other hand, in each of the comparative examples in which the resin layer (A) contains a photopolymerization initiator, the photopolymerization initiator absorbs light, so that the deep curing property is not obtained, and the fine line is dropped at the time of development.

(Examples 7 to 12, Comparative Example 5)

The resin compositions constituting each resin layer were prepared by mixing the materials described in the examples and the comparative examples respectively in accordance with the blend described in the following table, preliminarily mixing them with a stirrer, and kneading them with a three roll mill, , The resin layer (A) and the resin layer (B) were formed. The values in the table are parts by mass of solids, unless otherwise noted.

&Lt; Resolution (aperture size and minimum remaining line width) >

Each laminated structure thus obtained was exposed at 500 mJ / cm 2 using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp. The exposure pattern was a pattern for drawing a line having a width of 30/40/50/60/70/80/90/100 μm and a pattern for opening an opening of 300 μm. Then, after performing PEB for 30 minutes at 90 ℃ step, developing (30 ℃, 0.2㎫, 1 wt% Na ₂ CO ₃ aqueous solution) the cured by heat curing the pattern subjected to 60 seconds and a, 150 ℃ × 60 bun film &Lt; / RTI &gt; The obtained cured coating film was counted by using an optical microscope adjusted to 200 times the minimum remaining line width, and the opening size (design value 300 mu m) was measured, and the opening shape was photographed. The smaller the minimum remaining line width is, the better the deep curing property is. The results are shown in the following table and Figs. 3 (a) to 3 (i), respectively.

<Chemical resistance (electroless gold plating resistance)>

A commercially available electroless gold plating bath was used to coat the cured coating film on the substrate under the conditions of nickel 0.5 mu m and gold 0.03 mu m to evaluate whether or not the plating was impregnated on the plated evaluation substrate , And the presence or absence of peeling of the resist layer was evaluated by tape peeling. The criteria are as follows. The obtained results are shown in the following table.

○: Seeping and peeling are not seen.

?: A little seeping was confirmed after plating, but peeling after tape peeling was not observed.

X: There is peeling after tape peeling.

* 11) LUCIRIN TPO (acylphosphine oxide photopolymerization initiator, BASF Japan)

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

* 13) HCA-HQ: phenolic hydroxyl group-containing phosphorus compound (manufactured by Sankyo Co., Ltd.)

The laminated structures of Examples 7 to 12, in which the resin layer (A) was blended with a polymerization inhibitor, had a stable opening shape with a small degree of halation and a minimum remaining line width of 30 탆. On the other hand, in Example 6, which was the same as Example 12 except that no polymerization inhibitor was added, the aperture size and gold plating resistance were evaluated. The minimum remaining line width was 30 탆, And the aperture size was slightly reduced to 240 탆. Further, in Comparative Example 5, a photopolymerization initiator was used for the resin layer (A), so that the halation was prevented to some extent, but the gold plating resistance was poor, and the minimum line width and 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 having a resin layer (A) and a resin layer (B) laminated on a flexible printed wiring board via the resin layer (A)
Wherein the resin layer (B) comprises a photosensitive thermosetting resin composition comprising an alkali-soluble resin, a photopolymerization initiator, and a thermoreactive compound,
Wherein the resin layer (A) comprises an alkali-developable resin composition containing an alkali-soluble resin, a compound having an ethylenic unsaturated bond, a heat-reactive compound, and a polymerization inhibitor and not containing a photopolymerization initiator,
Wherein the blending amount of the polymerization inhibitor is 0.05 to 100 parts by mass relative to 100 parts by mass of the alkali soluble resin. The laminated structure according to claim 1, which is used for at least one of a bent portion and a non-bent portion of a flexible printed wiring board. The laminated structure according to claim 1, wherein the laminated structure is used for the use of at least one of a coverlay, a solder resist and an interlayer insulating material of a flexible printed wiring board. The dry film according to claim 1, wherein at least one side of the laminated structure is supported or protected by a film. A flexible printed wiring board comprising a flexible printed wiring board, a layer of a laminated structure according to claim 1 formed on the flexible printed wiring board, patterned by light irradiation, and a pattern formed integrally with a developer. delete

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