TWI626868B - Laminated resin structure, dry film and flexible printed circuit board - Google Patents

Abstract

The present invention provides a laminated resin structure capable of obtaining a protective film having excellent insulation and light-shielding properties.

The laminated resin structure system of the present invention has an adhesive layer (A), a protective layer (B) laminated on the flexible printed circuit board (1) via the adhesive layer (A), and the adhesive layer ( A) contains coloring agents other than carbon black.

Description

Laminated resin structure, dry film and flexible printed circuit board

The present invention relates to a laminated resin structure, a dry film, and a flexible printed circuit board, and particularly to a light-shielding laminated resin structure used in optical devices, electronic devices, and the like.

Conventionally, a flexible printed circuit board composed of a copper-clad laminate formed on a polyimide film with a circuit and a protective circuit cover layer has thinness, lightness, flexibility, and bending resistance. It is used in the drive unit typified by the bending part of mobile phones, hard drives, printers, and copiers. In addition, in recent years, the need to promote the compactness and weight reduction of electronic equipment has increased compared with the conventional rigid type, and the need for flexible printed circuit boards that are lightweight, occupy a small area, and allow free three-dimensional wiring. In addition, its use is not limited to pure continuous use, but also developed in parts installation, etc., with the diversification of use forms, gradually demanding various performance.

In such a case, the cover layer used as the circuit protective film of the flexible printed circuit board requires different characteristics from the circuit protective film of the rigid substrate. For example, a flexible printed circuit board is used for bending in a limited space within a frame or used as a driving part as described above, so consider Consider direct contact with the conductor. Therefore, what is necessary as an important characteristic in the cover layer as a circuit protection film is the electrical insulation in the film thickness direction.

On the other hand, flexible printed circuit boards used in optical devices, etc. are often used in optical devices such as cameras or optical pickup units of CD-ROM disk devices, so they are used in the cover The layer system uses a light-shielding property.

That is, the cover layer used in optical devices and the like is black for the following reasons: (1) when used in optical devices, to prevent light from entering the light-shielding portion, (2) the conductor diagram is not easy to see The comparison of types, and (3) improve design.

Conventionally, a light-shielding cover layer has been proposed, for example, a light-shielding cover film containing carbon black having a specific average particle diameter in either or both of an electrically insulating layer or a thermosetting adhesive layer (Patent Document 1), or A film made of a composition of polyimide resin containing a perylene black pigment at a specific ratio (Patent Document 2), etc.

[Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 9-135067

[Patent Document 2] Japanese Patent No. 4709326

However, in the case of the cover film described in Patent Document 1, since conductive carbon black is used, there is a disadvantage that the electrical insulation of the cover layer in the film thickness direction (Z-axis direction) is reduced. Therefore, it is generally considered that the insulating property of the film thickness direction is improved by making the cover film into a laminated structure. However, when carbon black is used, the electrical insulation will still be reduced.

On the other hand, when a perylene black pigment is used like the polyimide film described in Patent Document 2, this pigment has poor color rendering power and light-shielding property compared to carbon black, so if it is used only, sufficient light-shielding is obtained The amount of resistance, there is still a tendency to reduce insulation.

Therefore, an object of the present invention is to provide a laminated resin structure, a dry film, and a flexible printed circuit board that can obtain a protective film having excellent insulating properties and light shielding properties.

In order to solve the above-mentioned problems, the laminated resin structure of the present invention has an adhesive layer (A) and a protective layer (B) laminated on a flexible printed circuit board via the adhesive layer (A). Therefore, the aforementioned adhesive layer (A) contains a coloring agent other than carbon black.

In the present invention, it is preferable that the adhesive layer (A) contains a perylene-based coloring agent, and it is preferable that the black color is exhibited.

Furthermore, in the present invention, it is preferable that the adhesive layer (A) is thicker than the protective layer (B).

The laminated resin structure of the present invention can be used for flexible At least any one of the bent portion and the non-bent portion of the flexible printed circuit board can be used to form at least any one of the cover layer and the solder resist layer of the flexible printed circuit board.

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

In addition, the flexible printed circuit board of the present invention is characterized by having a protective film formed by hardening the laminated resin structure on the flexible printed circuit board.

According to the present invention, it is possible to provide a laminated resin structure capable of obtaining a protective film having excellent insulation and light-shielding properties. In addition, a flexible printed circuit board having a protective film obtained by curing the laminated resin structure can be provided.

1‧‧‧Laminated resin structure

2‧‧‧Flexible substrate

3‧‧‧Copper circuit

A‧‧‧Next layer

B‧‧‧Protective layer

[Figure 1] This is a schematic cross-sectional view of a flexible printed circuit board laminated with a laminated resin structure according to an embodiment of the present invention.

[Figure 2] This is a schematic cross-sectional view of the flexible printed circuit board after patterning and development of the laminated resin structure shown in Figure 1.

[Figure 3] This is a schematic cross-sectional view of a flexible printed circuit board having an adhesive layer (A) composed of a thermosetting resin composition.

[Figure 4] A graph showing the a * value and b * value of the colorant.

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

Fig. 1 shows a laminated resin structure according to an embodiment of the present invention. The laminated resin structure 1 shown in the figure is provided on a flexible printed circuit board on which a copper circuit 3 is arranged on a flexible substrate 2, and an adhesive layer (A) and a protective layer are sequentially laminated in this order. B) Two-layer structure.

The next layer (A) is used to attach the protective layer (B) to the inner layer of the flexible printed circuit board, and contains a coloring agent other than carbon black. The next layer (A) is formed by the resin composition (A1), and the resin composition (A1) may be photosensitive or thermosetting. The photosensitive resin composition may be a developing type or a non-developing type.

Here, the adhesive layer (A) preferably has a light-shielding property, and although it is more preferably black, for example, it may be other colors such as blue and red.

On the other hand, the protective layer (B) is an outer layer, and is laminated on the flexible printed circuit board by the adhesive layer (A). The protective layer (B) is formed of a resin composition (B1) different from the resin composition (A1). The resin composition (B1) may be photosensitive or thermosetting. The photosensitive resin composition may be a developing type or a non-developing type.

The combination of the resin composition (A1) and (B1) includes: a thermosetting resin composition (A1) and a thermosetting resin composition (B1), Thermosetting resin composition (A1) and photosensitive resin composition (B1), photosensitive resin composition (A1) and thermosetting resin composition (B1), photosensitive resin composition (A1) and photosensitive resin Combination of composition (B1).

In particular, when both the adhesive layer (A) and the protective layer (B) of the laminated resin structure of the present invention are formed of photosensitive resin compositions (A1) and (B1), the adhesive layer (A ) And the protective layer (B) are patterned, and a fine pattern can be formed, which is preferable.

Here, patterning means that the portion irradiated with light changes from a non-developable state to a developable state (positive type), or from a developable state to a non-developable state (negative type) . In addition, the formation of the pattern means that the light-irradiated portion is developed and the unirradiated portion remains in a pattern shape (positive type), or the unirradiated portion is developed and remains in a pattern shape (negative type). Here, the pattern means a hardened object in a pattern shape, that is, a protective film.

The resin compositions (A1) and (B1) are preferably development-type photosensitive resin compositions. The development-type photosensitive resin compositions (A1) and (B1) may be positive or negative.

As for the positive photosensitive resin composition, as long as the polarity changes before and after light irradiation, and the light irradiation portion (also referred to as the exposure portion) is dissolved by the developer, a well-known conventional one can be used. For example, a composition containing a diazonaphthoquinone compound and an alkali-soluble resin can be mentioned.

The negative photosensitive resin composition can use a well-known conventional person as long as the light irradiation part becomes insoluble in a developing liquid. Examples include: a composition containing a photoacid generator and an alkali-soluble resin, a composition containing a photobase generator and an alkali-soluble resin, a composition containing a photopolymerization initiator and an alkali-soluble resin, and the like.

The combination of the developing photosensitive resin composition (A1) and (B1), as long as it is a positive photosensitive resin composition (A1), a positive photosensitive resin composition (B1), and a negative photosensitive resin composition (A1 ) And any of the combinations of the negative photosensitive resin composition (B1).

Examples include: a composition containing a photobase generator (A1) and a composition containing a photobase generator (B1), a composition containing a photobase generator (A1) and a composition containing a photopolymerization initiator ( B1), a composition containing a photopolymerization initiator (A1) and a composition containing a photobase generator (B1), a composition containing a photopolymerization initiator (A1) and a composition containing a photopolymerization initiator The combination of (B1), etc., can be selected according to the embodiment.

Since the laminated resin structure of the present invention is used for a flexible printed circuit board, it is preferable to reduce deformation and warpage during curing. Therefore, a composition containing the above-mentioned alkali generator is preferable. Such a composition also includes, for example, a composition containing a photobase generator and a thermosetting resin, and cured by an addition reaction.

In addition, it can also be only the resin composition (A1) and the resin group Either one of the products (B1) has a photoacid generator, a photobase generator, or a photopolymerization initiator, and the other does not contain any of the photoacid generator, photobase generator, and photopolymerization initiator Composition. In this case, it is only necessary to harden the other composition by the photoacid generator, the photobase generator, or the photopolymerization initiator contained in the one composition.

The method of forming the pattern of the laminated resin structure may be a method of developing with an organic solvent or an alkaline aqueous solution, or a method of directly forming the pattern by screen printing or the like.

The non-developable photosensitive resin composition includes a composition containing a photopolymerization initiator and a radically polymerizable component. The thermosetting resin composition includes a composition containing a thermosetting resin.

[Colorant]

The coloring agent blended in the adhesive layer (A) may be anything other than carbon black, and one or more coloring agents may be combined. The coloring agent is preferably one that imparts light-shielding properties to the adhesive layer (A), and although it is more preferably a black coloring agent, for example, it may be other colors. The colorant may be any of pigments, dyes, and pigments.

Although the blending amount of the coloring agent blended in the adhesive layer (A) is not particularly limited, it is preferably set to 1 to 80% by mass in all components of the adhesive layer (A) except the organic solvent, and more preferably It is 3 to 60% by mass, and even more preferably 5 to 40% by mass.

Examples of the black colorant system include black lead system, iron oxide system, anthraquinone system, cobalt oxide system, copper oxide system, manganese system, antimony oxide system, and nickel oxide system Series, perylene series, molybdenum sulfide or bismuth sulfide and titanium black. From the standpoint of electrical insulation, the best is the coloring agent of the perylene system.

In addition, the adhesive layer (A) preferably exhibits black color by a combination of a perylene-based colorant, the perylene-based colorant, and a coloring agent as a complementary color relationship.

Perylene-based colorants have less absorption in the ultraviolet region than the above-mentioned carbon black, and can improve the resolution of the adhesive layer (A) during patterning by light irradiation. In addition, the perylene-based colorant has sufficient coloring power, and can be used in combination with a complementary colorant to form a black adhesive layer (A) having excellent resolution and color rendering power.

The perylene-based colorant can be a conventionally well-known one, and any one of a pigment, dye, and pigment can be used as long as it is a perylene-based colorant.

Examples of perylene-based colorants include those with green, yellow, orange, red, purple, black, and other colors that have a color index (C.I .; issued by The Society of Dyers and Colourists) as follows.

-Green: Solvent Green 5

-Orange: Solvent Orange 55

-Red: Solvent Red 135,179; Pigment Red 123,149,166,178,179,190,194,224;

-Purple: Pigment Violet 29

-Black: Pigment Black 31,32

Perylene-based colorants other than the above can also be used, for example, BASF, which is known as a black organic pigment that transmits infrared light although it has a colorless index number The Lumogen (registered trademark) Black FK4280, Lumogen Black FK4281, Lumogen F Yellow 083, Lumogen F Orange 240, Lumogen F Red 305, Lumogen F Green 850, and other perylene colorants In the same way, the ultraviolet region absorbs little, and the coloring power is high, so it can be suitably used.

(Complementary colorant)

Hereinafter, the complementary colorant used in combination with the perylene-based colorant in the present invention will be described. First, the complementary color relationship of the present invention will be described.

The coloring agent may not show a color like a color index, so the color tone of the cured coating film of the photosensitive resin composition is measured according to the method specified in JISZ8729, and the representative L is confirmed by the coordinate axis (refer to FIG. 4) * a * b * The a * value and b * value of the colors in the color system are selected to make the (a * value, b * value) of the cured coating film obtained in combination with the perylene coloring agent as close as possible The coloring agent of (0,0) is used as the coloring agent of complementary color relationship. Here, the thickness of the cured coating film is not particularly limited as long as it appears black.

In addition, as close as possible to the (a * value and b * value) of (0,0), the a value and the b value are preferably in the range of -5 to +5, more preferably in the range of -2 to +2. In addition, as the coloring agent of the complementary color relationship, it may be a perylene coloring agent or a coloring agent other than the perylene coloring agent.

The coloring agent of the relationship between perylene-based colorants and complementary colors, as long as by combining with the perylene-based colorants, the surface color of the colorants of each other is a * value It is sufficient if the b * value is close to any one of the coloring agents, and the following coloring agents can be cited.

The preferred combination with perylene-based colorants is the combination of Pigment Red 149,178,179 and green anthraquinone-based colorants (Solvent Green 3, Solvent Green 20, Solvent Green 28, etc.), if it is a mixture of perylene-based colorants (combination ), It is a combination of red perylene-based colorants (Pigment Red 149,178,179) and black perylene-based colorants (Pigment Black 31, 32), black perylene-based colorants (Pigment Black 31, 32) and the same black perylene-based colorants (Lumogen (registered trademark) Black FK4280.4281) combination.

In addition, the adhesive layer (A) can be composed of: a combination of a yellow colorant and a purple colorant, a combination of a yellow colorant and a blue colorant and a red colorant, a combination of a green colorant and a purple colorant, a green coloration Any combination selected from the group consisting of a combination of an agent and a red colorant, a combination of a yellow colorant and a purple colorant and a blue colorant, and a combination of a green colorant and a red colorant and a blue colorant . In addition, a purple colorant, an orange colorant, a brown colorant, etc. may be combined.

When the coloring agent with the above complementary color relationship is used, the light absorption is less than when the coloring agent contains black coloring agent. Therefore, in the photosensitive resin composition, even if the content of the coloring agent is increased in order to increase the blackness, the photocuring can be sufficiently performed to improve the photosensitivity and resolution compared to the case of the black colorant. As a result, it can be effectively applied to high-density and high-definition flexible printed circuit boards.

The blue colorant series include phthalocyanine series, anthraquinone series, etc., and Compounds classified as Pigment, Solvent, etc. In addition to this, metal-substituted or unsubstituted phthalocyanine compounds can also be used.

The red colorant system includes monoazo system, disazo system, azo lake system, benzimidazolone system, perylene system, diketopyrrolopyrrole system, condensed azo system, anthraquinone system, quinacridone Department etc.

The yellow colorant system includes monoazo system, disazo system, condensed azo system, benzimidazolone system, isoindolinone system, anthraquinone system and the like.

The green colorant system includes phthalocyanine system and anthraquinone system. In addition to this, metal-substituted or unsubstituted phthalocyanine compounds can also be used.

Purple colorant, orange colorant, brown colorant, specifically include: Pigment Violet 19,23,29,32,36,38,42; Solvent Violet 13,36; CI pigment orange 1, CI pigment orange 5. CI Color Orange 13, CI Color Orange 14, CI Color Orange 16, CI Color Orange 17, CI Color Orange 24, CI Color Orange 34, CI Color Orange 36, CI Color Orange 38, CI Color Orange 40, CI Color Orange 43, CI pigment orange 46, CI pigment orange 49, CI pigment orange 51, CI pigment orange 61, CI pigment orange 63, CI pigment orange 64, CI pigment orange 71, CI pigment orange 73; CI pigment brown 23, CI pigment brown 25; CI Pigment Black 1, CI Pigment Black 7, etc.

Although the protective layer (B) may contain a colorant, it is preferably free of carbon black. The blending amount of the coloring agent blended in the protective layer (B) can be contained to the extent that the effect of the present invention is not impaired, for example, in all components of the protective layer (B) except the organic solvent It is preferably less than 5% by mass, more preferably 4% by mass or less, and even more preferably 3% by mass or less.

Since the content of the coloring agent in the protective layer (B) is small and no surface defect is formed, the insulation in the Z-axis direction is excellent.

In the present invention, the adhesion layer (A) contains a coloring agent other than carbon black, and it is preferred that the protective layer (B) contains no coloring agent, or almost no one, whereby the insulation in the Z-axis direction is excellent and the light-shielding property Excellent.

The total film thickness of the laminated resin structure of the present invention is preferably 100 μm or less, and more preferably in the range of 4 to 80 μm. For example, when the laminated resin structure is two layers, the adhesive layer (A) is, for example, 3 to 60 μm. With such a thickness, the adhesive layer (A) can be adhered to the circuit without a gap. On the other hand, the protective layer (B) has a thickness of, for example, 1 to 20 μm.

The adhesive layer (A) of the laminated resin structure of the present invention is preferably thicker than the protective layer (B) from the viewpoint of circuit followability and flexibility of the protective film.

The laminated resin structure can be used for at least any one of the bent portion and the non-bent portion of the flexible printed circuit board, specifically, it can be used to form the cover layer and the solder of the flexible printed circuit board At least any one of the resist layers. Examples of non-bent parts include wafer mounting parts.

Although the example shown in the figure has a two-layer structure, the laminated structure of the present invention is not limited to two layers, and may have three or more layers. However, the outermost layer is the protective layer (B).

FIG. 2 is a cross section of a state where a pattern is formed on the laminated resin structure 1 on the flexible printed circuit board shown in FIG. 1. Pattern formation can be performed by punching method, pattern printing method, organic solvent-based imaging method, or alkali imaging method according to the type of resin.

As described above, in the case where carbon black is blended into the outer layer in order to improve the light-shielding property, although the breakdown voltage is lowered to cause insulation breakdown, by adopting the laminated structure as in the present invention, the damage can not be reduced The voltage improves the light-shielding property well.

(Dry film)

The dry film of the present invention includes a carrier film (support) and the laminated resin structure of the present invention formed on the carrier film, and at least one side of the laminated resin structure is supported or held by the carrier film .

The dry film is manufactured by diluting the resin composition (B1) with an organic solvent to adjust to an appropriate viscosity, and applying a dot coater to the carrier film to a uniform thickness. After drying, the protective layer (B) is formed. Next, on the protective layer (B), the adhesive layer (A) is formed by the resin composition (A1) to obtain the dry film of the present invention.

The carrier film uses a plastic film. Although the thickness of the carrier film is not particularly limited, in general, it can be appropriately selected within the range of 10 to 150 μm. After forming the laminated resin structure on the carrier film, a peelable cover layer may be further laminated.

(Flexible printed circuit board)

The flexible printed circuit board of the present invention has a protective film formed by hardening a laminated resin structure on a flexible printed circuit board. The protective film is preferably any one of a cover layer and a solder resist layer.

<Manufacturing method of laminated resin structure>

The method of forming the adhesive layer (A) and the protective layer (B) on the flexible printed circuit board may be the lamination method using the dry film of the present invention, or the resin composition (A1), ( B1) Coating method. In the lamination method, the lamination machine or the like is used to adhere to the flexible printing in such a manner that the adhesive layer (A) is in contact with at least one of the bent portion and the non-bent portion of the flexible printed circuit board On the circuit board.

The coating method, for example, by a screen printing method, a resin composition (A1) and a resin composition (B1) are sequentially coated on a flexible printed circuit board, and dried to form an adhesive layer (A) and Protective layer (B).

Alternatively, the flexible printed circuit board may be coated with the resin composition (A1), dried to form an adhesive layer (A), and the adhesive layer (A) may be laminated with the resin composition (B1). Thin film, and the method of forming the protective layer (B).

Conversely, it is also possible to form an adhesive layer (A) by laminating a thin film composed of the resin composition (A1) on a flexible printed circuit board, and to coat the adhesive layer (A) with a resin The composition (B1) is dried to form a protective layer (B).

<Manufacturing method of flexible printed circuit board using thermosetting laminate resin structure>

The thermosetting laminate resin structure only needs to have at least one of the resin composition (A1) and the resin composition (B1) being a thermosetting resin composition. For example, the screen printing method is equivalent to a flexible printed circuit board The thermosetting resin composition (A1) is applied and dried, as shown in FIG. 3, to form the pattern of the adhesive layer (A). Next, the thermosetting resin composition (B1) is applied by screen printing or the like in a manner corresponding to the pattern of the adhesive layer (A), and dried to form a protective layer as shown in FIG. 2 (B) The pattern. With this, the pattern of the thermosetting laminate resin structure is formed.

Next, the pattern of the protective film is formed by heating the thermosetting laminate resin structure at 130 to 200 ° C. for 30 to 120 minutes and thermally curing it.

<Manufacturing method of flexible printed circuit board using non-developable photosensitive laminated resin structure>

The non-developable photosensitive laminated resin structure only needs to be at least one of the resin composition (A1) and the resin composition (B1) to be a non-developable photosensitive resin composition.

For example, using a non-developable photosensitive resin composition (A1) and a non-developable photosensitive resin composition (B1), an adhesive layer is formed on a flexible printed circuit board by the above coating method ( A) A non-developable photosensitive laminated resin structure with a protective layer (B). Thereafter, the non-development type photosensitive laminated resin structure is irradiated with light such as ultraviolet rays by a contact type or a non-contact type, and cured, thereby forming a pattern of a cured film. In addition, it can be heated after photocuring, or light irradiation and heating can be performed simultaneously.

<Flexibility of using a negative-type laminated resin structure containing a photopolymerization initiator Printed circuit board manufacturing method>

In the case of a negative-type laminated resin structure containing a photopolymerization initiator, it suffices that at least one of the resin composition (A1) and the resin composition (B1) contains a photopolymerization initiator.

For example, a photosensitive resin composition (A1) containing a photopolymerization initiator and a photosensitive resin composition (B1) containing a photopolymerization initiator are used on the flexible printed circuit board by the above lamination method and the like A negative-type laminated resin structure having an adhesive layer (A) and a protective layer (B) is formed thereon. Thereafter, the negative-type laminated resin structure is irradiated with light in a negative pattern by a contact type or a non-contact type, and a non-irradiated portion is developed to form a pattern together to obtain a protective film. In addition, in the case of a composition containing a thermosetting component, heat curing by heating to a temperature of, for example, about 140 to 180 ° C can form heat resistance, chemical resistance, moisture resistance, and adhesion Protective film with excellent electrical characteristics and other characteristics. Since the negative-type laminated resin structure contains a photopolymerization initiator, the light irradiation part is hardened by radical polymerization.

<Manufacturing method of flexible printed circuit board using negative laminated resin structure containing photobase generator>

In the case of a negative-type laminated resin structure containing a photobase generator, it suffices that at least any one of the resin composition (A1) and the resin composition (B1) contains a photobase generator. For example, in the same manner as the method for forming a negative-type laminated resin structure containing a photopolymerization initiator, a bonding layer (A) containing a photobase generator and a guarantee containing a photobase generator are formed Negative laminated resin structure of the sheath (B). Thereafter, for the negative-type laminated resin structure, after irradiating light in a negative pattern to generate alkali from the photobase generator to harden the light-irradiated portion, the pattern of the protective film is formed by removing the unirradiated portion by development . Here, it is preferable to heat the laminated resin structure after light irradiation.

Then, it can be further irradiated with ultraviolet rays after development to improve the insulation reliability of the protective film. In addition, heating (post-curing) may be performed after development, or ultraviolet irradiation and heating may be performed simultaneously after development.

<Manufacturing method of flexible printed circuit board using negative laminated resin structure containing photoacid generator>

In the case of a negative-type laminated resin structure containing a photoacid generator, it suffices that at least one of the resin composition (A1) and the resin composition (B1) contains a photoacid generator. For example, in the same manner as the method for forming a negative-type laminated resin structure containing a photopolymerization initiator, an adhesive layer (A) containing a photoacid generator and a protective layer (B) containing a photoacid generator are formed Of negative laminated resin structure. Thereafter, the negative-type laminated resin structure is irradiated with light, and an acid is generated from the photoacid generator to harden the light-irradiated portion. Then, the pattern of the protective film is formed by the same developing method as described above.

<Manufacturing method of flexible printed circuit board using positive laminated resin structure>

In the case of a positive laminated resin structure, as long as the resin composition At least one of (A1) and the resin composition (B1) may be a positive composition. For example, on the flexible printed circuit board, in the same manner as the formation method of the negative-type laminated resin structure containing the photopolymerization initiator, a positive-type adhesive layer (A) and a positive-type protective layer (B ) Is a positive laminate resin structure. Thereafter, the positive-type laminated resin structure is irradiated with light in a pattern. After the light is irradiated, the pattern of the protective film is formed by removing the light irradiated part by the same developing method as described above.

For the exposure machine used for the above light irradiation, as long as it is equipped with a high-pressure mercury lamp tube, an ultra-high pressure mercury lamp tube, a metal halogen lamp, a mercury short-arc lamp, etc., a device that irradiates ultraviolet rays in the range of 350 to 450 nm, and furthermore, direct A rendering device (for example, a laser direct imaging device that draws a portrait by direct laser using CAD data from a computer).

The laser light source of the direct marking machine is a laser light with a maximum wavelength in the range of 350 to 450 nm, and can be either a gas laser or a solid laser. Although the amount of exposure required for image formation varies depending on the film thickness, etc., in general, it can be set in the range of 20 to 1500 mJ / cm ² . The developing method can be carried out by liquid method, shower method, spray method, brush method, etc. The developing solution can use potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, Alkaline aqueous solutions such as amines.

[Example]

Although the examples and the comparative examples are shown below to specifically describe the present invention, the present invention is not limited to the following examples.

(Examples 1, 2 and Comparative Examples 1 to 4)

Various components other than the coloring agent and the coloring agent are blended in the ratio (parts by mass) shown in Table 1 below, and after preliminary mixing with a blender, they are kneaded with a 3-roll mill to prepare photosensitive resin compositions (A1 ) And photosensitive resin composition (B1).

(Photosensitive resin composition (A1))

Carboxylic acid modified bisphenol F epoxy acrylate (manufactured by Nippon Kayaku Co., Ltd.): 100 parts by mass

Trimethylolpropane EO modified triacrylate (East Asia Synthetic Company System): 16 parts by mass

Bisphenol A epoxy resin (molecular weight: 900) (manufactured by Mitsubishi Chemical Corporation): 28 parts by mass

Bisphenol A epoxy resin (molecular weight: 500) (manufactured by Mitsubishi Chemical Corporation): 18 parts by mass

Aminoalkylphenol photopolymerization initiator (made by BASF Japan): 10 parts by mass

Ethylmethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.): 1 part by mass

(Photosensitive resin composition (B1))

Carboxylic acid modified cresol novolac epoxy acrylate (made by DIC): 100 parts by mass

Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.): 22 parts by mass

Bisphenol A novolak epoxy resin (manufactured by DIC): 23 parts by mass

Tetramethylbiphenyl epoxy resin (manufactured by Mitsubishi Chemical Corporation): 17 parts by mass

Aminoalkylphenol photopolymerization initiator (made by BASF Japan): 10 parts by mass

Diethylthioxanthone sensitizer (manufactured by Nippon Kayaku Co., Ltd.): 1 part by mass Barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.): 100 parts by mass

(Examples 1, 2 and Comparative Example 4)

After the resin composition (B1) is coated on the carrier film and dried to form the protective layer (B), the photosensitive resin composition (A1) is coated on the surface and dried to form the adhesive layer (A) to obtain Dry film. The dry film was pressure-bonded to a flexible printed circuit board at 120 ° C to form a laminated resin structure. (A) The thickness of the adhesive layer is 30 μm, and (B) The thickness of the protective layer is 10 μm.

Next, the laminated resin structure was exposed to light with an exposure amount of 500 mJ / cm ² using an exposure device (HMW-680-GW20) equipped with a metal halogen lamp through a negative mask, and developed to form a protective film.

(Comparative examples 1 to 3)

After coating the photosensitive resin composition (B1) on the flexible printed circuit board, it is dried to form only the protective layer (B). The thickness of the protective layer (B) is 10 μm.

Next, the protective layer (B) was exposed to light with an exposure amount of 500 mJ / cm ² using an exposure device (HMW-680-GW20) equipped with a metal halide lamp through a negative mask, and developed to form a protective film.

<Breakdown voltage>

Using a voltage withstand tester TOS5051A manufactured by Kikusui Electronics Co., Ltd., the voltage was increased by 0.5 kV / sec in the thickness direction of the protective film (Z-axis direction), and the voltage for conducting was used as the breakdown voltage.

<Shading properties>

For the evaluation substrate on which the protective films of Examples and Comparative Examples were formed, the light-shielding property was evaluated visually. The case where the light-shielding property is good is regarded as ○, and the case where it is poor is regarded as ×.

Based on the results shown in Table 1 above, the protective film obtained from the laminated resin structures of Examples 1 and 2 had a high breakdown voltage on a flexible printed circuit board and good light-shielding properties. In contrast, in Comparative Example 1, the breakdown voltage was low and the light shielding property was poor, and in Comparative Examples 2 to 4, the breakdown voltage was lower.

(Examples 3 and 4 and Comparative Examples 5 to 8)

Various components other than the coloring agent and the coloring agent are blended in the ratio (parts by mass) shown in Table 2 below, and after preliminary mixing with a blender, they are kneaded with a 3-roll mill to prepare thermosetting resin compositions ( A1) and thermosetting resin composition (B1). For the obtained Examples 3 and 4, and Comparative Examples 5 to 8, the evaluation results in the same manner as in Example 1 and the like are shown in Table 2 below.

(Thermosetting resin composition (A1))

Bisphenol A epoxy resin (molecular weight: 900) (manufactured by Mitsubishi Chemical Corporation): 60 parts by mass

Bisphenol A epoxy resin (molecular weight: 380) (manufactured by Mitsubishi Chemical Corporation): 40 parts by mass

Novolac type phenol resin (made by Minghe Chemical): 25 parts by mass

Ethylmethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.): 1 part by mass

(Thermosetting resin composition (B1))

Phenolic novolac epoxy resin (manufactured by DIC): 40 parts by mass

Bisphenol A epoxy resin (molecular weight: 900) (manufactured by Mitsubishi Chemical Corporation): 30 parts by mass

Bisphenol A epoxy resin (molecular weight: 380) (manufactured by Mitsubishi Chemical Corporation): 20 parts by mass

Novolac type phenol resin (made by Minghe Chemical): 28 parts by mass

Ethylmethylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.): 1 part by mass

Barium sulfate (manufactured by Sakai Chemical Industry Co., Ltd.): 100 parts by mass

(Examples 3, 4 and Comparative Example 8)

On the flexible printed circuit board, the thermosetting resin composition (A1) was applied in a pattern by a screen printing method, and dried at 100 ° C. for 20 minutes to form an adhesive layer (A). Thereafter, the thermosetting resin composition (B1) was applied on the adhesive layer (A) by screen printing in a manner corresponding to the pattern of the adhesive layer (A), and heated at 150 ° C. for 60 minutes Heat hardens to form a protective layer (B). (A) The thickness of the adhesive layer is 30 μm, and (B) the protective layer (B) is 10 μm.

(Comparative Examples 4-7)

On a flexible printed circuit board, the thermosetting resin composition (B1) is applied in a pattern by screen printing method, and heated at 150 ° C for 60 minutes to thermally cure to form a protective layer (B ). (B) The protective layer (B) is 40 μm.

Based on the results shown in Table 2 above, the protective film obtained from the laminated resin structures of Examples 3 and 4 had a high breakdown voltage on a flexible printed circuit board and good light-shielding properties. In contrast, in Comparative Example 5, it is obtained that the breakdown voltage is low and the light-shielding property is poor, and in Comparative Example 6 ~ In 8, the destruction voltage is lower.

Claims (6)

A laminated resin structure having a black adhesive layer (A) and a laminated resin structure laminated on a protective layer (B) of a flexible printed circuit board via the adhesive layer (A) It is characterized in that the black-colored adhesive layer (A) contains a perylene-based colorant, and the blending amount of the perylene-based colorant is 13 in all components of the adhesive layer (A) except the organic solvent. ~ 80% by mass, the black adhesive layer (A) and the protective layer (B) are made of a photosensitive resin composition. The laminated resin structure according to claim 1, wherein the adhesive layer (A) is thicker than the protective layer (B). The laminated resin structure as described in claim 1 or 2 is used for at least one of a bent portion and a non-bent portion of a flexible printed circuit board. The laminated resin structure according to claim 1 or 2, which is used to form at least one of a cover layer and a solder resist layer of a flexible printed circuit board. A dry film characterized in that at least one side of the laminated resin structure as described in claim 1 or 2 is supported or protected by a film. A flexible printed circuit board is characterized by having a protective film formed by curing the laminated resin structure as described in claim 1 or 2 on a flexible printed circuit board.