TW201513757A - Laminated resin structure, dry film, and flexible printed wire board - Google Patents

Abstract

Provided is a laminated resin structure capable of achieving a protective film which is superior in insulation properties and light barrier properties. The present invention is a laminated resin structure (1) having an adhesion layer (A), and a protective layer (B) stacked upon a flexible base material (2) across the adhesion layer (A), wherein the adhesion layer (A) contains a colorant other than carbon black. On a flexible printed wire board, the laminated resin structure (1) is cured upon the flexible printed wire board so as to serve as a protective film.

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 more particularly to a light-shielding laminated resin structure used for an optical device, an electronic device, or the like.

Conventionally, a flexible printed circuit board comprising a copper-clad laminate formed on a polyimide film and a cover layer of a protective circuit has thinness, lightness, flexibility, and bending resistance. It is used in a drive unit represented by a bent portion of a mobile phone, a hard drive, a printer, and a copying machine. In addition, in recent years, the electronic device has been reduced in size and weight, and the need for a flexible printed circuit board that is lightweight and has a small footprint and free three-dimensional wiring has been gradually improved as compared with the conventional hard type. Furthermore, the use is not limited to simple continuous use, but also to the installation of parts, and various performances are gradually required as the form of use is diversified.

In such a case, the cover layer used as the circuit protective film of the flexible printed circuit board is required to have characteristics different from those of the circuit protective film of the rigid substrate. For example, a flexible printed circuit board is used for bending in a limited space in a casing, or is used for a driving portion as described above. Consider the case of direct contact with the conductor. Therefore, it is necessary to have electrical insulation in the film thickness direction as an important characteristic in the coating layer as a circuit protection film.

On the other hand, a flexible printed circuit board used in an optical device or the like is often used in an optical device such as an optical pickup unit of a camera or a CD-ROM disk device. The layer system uses a light-blocking person.

In other words, the cover layer used in an optical device or the like is black for the following reasons: (1) preventing light from entering the light shielding portion when used in an optical device, and (2) not easily seeing a conductor pattern. The contrast between the types, and (3) improve the design.

In the light-shielding coating layer, 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 is proposed (Patent Document 1), or A film made of a composition of a polyimine pigment containing a perylene black pigment in a specific ratio (Patent Document 2).

[Previous Technical Literature] [Patent Literature]

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

[Patent Document 2] Japanese Patent No. 4709326

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

On the other hand, in the case where a black pigment is used in the same manner as the polyimide film described in Patent Document 2, the pigment has poor coloring power and light-shielding property as compared with carbon black. Therefore, sufficient shading is obtained only when used. The amount of sex tends to reduce the insulation.

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

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

In the present invention, it is preferred that the adhesive layer (A) contains an anthraquinone-based coloring agent, and it is preferable to exhibit a black color.

Furthermore, in the 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 flexibility At least one of the curved portion and the non-bending portion of the printed circuit board can be used to form at least one of a cover layer and a solder resist layer for forming a 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.

Further, the flexible printed circuit board of the present invention is characterized in that it has a protective film obtained by curing the laminated resin structure on a flexible printed circuit board.

According to the present invention, it is possible to provide a laminated resin structure which can provide a protective film having excellent insulating properties and light blocking properties. Further, 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‧‧‧Bronze circuit

A‧‧‧Next layer

B‧‧‧Protective layer

[Fig. 1] Fig. 1 is a schematic cross-sectional view showing a flexible printed circuit board in which a laminated resin structure is laminated according to an embodiment of the present invention.

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

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

[Fig. 4] is a graph showing the a* value and the b* value of the colorant.

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

Fig. 1 is a view showing a laminated resin structure according to an embodiment of the present invention. The laminated resin structure 1 shown in the drawing has a laminate (A) and a protective layer laminated on a flexible printed circuit board on which the copper substrate 3 is disposed on the flexible substrate 2, respectively. B) The two-layer structure.

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

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

On the other hand, the protective layer (B) is an outer layer which 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), and the resin composition (B1) may be photosensitive or thermosetting. The photosensitive resin composition may be of a development type or a non-development type.

Examples of the combination of the resin composition (A1) and (B1) include a thermosetting resin composition (A1) and a thermosetting resin composition (B1). Thermosetting resin composition (A1), photosensitive resin composition (B1), photosensitive resin composition (A1), thermosetting resin composition (B1), photosensitive resin composition (A1), and photosensitive resin A combination of the compositions (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 the photosensitive resin compositions (A1) and (B1), the adhesive layer can be made by light irradiation (A). It is preferable to form a pattern with the protective layer (B) and form a fine pattern.

Here, the patterning means that the portion irradiated with light changes from a state in which the image is not visible to a state in which the image can be developed (positive type), or a state in which the image can be developed to a state in which the image cannot be developed (negative type). . Further, the formation of the pattern means that the portion where the light-irradiated portion is developed without being irradiated remains in a pattern (positive shape), or the portion where the unirradiated portion is developed is left in a pattern (negative type). Here, the pattern means a cured product of a pattern, that is, a protective film.

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

The positive photosensitive resin composition can be used as long as it is a light-irradiating portion (also referred to as an exposure portion) by a developing liquid by a change in polarity before and after light irradiation. For example, a composition containing a diazonaphthoquinone compound and an alkali-soluble resin can be mentioned.

The negative-type photosensitive resin composition can be used by a well-known person as long as it is insoluble in the developing liquid. For example, 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 can be mentioned.

The combination of the development type photosensitive resin composition (A1) and (B1) is a positive photosensitive resin composition (A1), a positive photosensitive resin composition (B1), and a negative photosensitive resin composition (A1). Any combination with the negative photosensitive resin composition (B1) may be used.

For example, a composition containing a photobase generator (A1), a composition containing a photobase generator (B1), a composition containing a photobase generator (A1), and a composition containing a photopolymerization initiator (for example) B1), a composition containing a photopolymerization initiator (A1), 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) and the like can be selected in accordance with 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, it is preferable to contain the composition of the above-mentioned alkali generating agent, and such a composition also contains, for example, a composition containing a photobase generating agent and a thermosetting resin which are hardened by an addition reaction.

In addition, it may be a resin composition only (A1) and a resin group. One of the products (B1) has a photoacid generator, a photobase generator, or a photopolymerization initiator, and the other does not contain any of a photoacid generator, a photobase generator, and a photopolymerization initiator. Composition. In this case, the other composition may be cured by a photoacid generator, a photobase generator, or a photopolymerization initiator contained in one of the compositions.

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

The non-developing photosensitive resin composition is a composition containing a photopolymerization initiator and a radical polymerizable component. The thermosetting resin composition is a composition containing a thermosetting resin.

[Colorant]

The coloring agent to be blended in the adhesive layer (A) may be one or two or more kinds of coloring agents as long as it is carbon black. The coloring agent is preferably one which imparts light blocking properties to the adhesive layer (A). More preferably, for example, it is a black coloring agent, but it may be other colors. The coloring agent may be any of a pigment, a dye, and a coloring matter.

The blending amount of the coloring agent to be blended in the adhesive layer (A) is not particularly limited, but is preferably 1 to 80% by mass, and more preferably all of the components of the adhesive layer (A) other than the organic solvent. It is 3 to 60% by mass, and more preferably 5 to 40% by mass.

Examples of the black colorant include black lead, iron oxide, lanthanum, cobalt oxide, copper oxide, manganese, lanthanum oxide, and nickel oxide. Department, lanthanum, molybdenum sulfide or strontium sulfide and titanium black. From the viewpoint of electrical insulation, a particularly preferred one is a tanning agent.

Further, the adhesive layer (A) preferably exhibits a black color by a combination of an anthraquinone coloring agent, the anthraquinone coloring agent, and a coloring agent as a complementary color relationship.

The oxime coloring agent has less absorption in the ultraviolet region than the carbon black described above, and enhances the resolution of the adhesive layer (A) in patterning by light irradiation. Further, the oxime-based coloring agent has sufficient coloring power and can be used in combination with a complementary coloring agent to form a black adhesive layer (A) excellent in resolution and coloring power.

The oxime coloring agent can be used by any conventionally known one, and any of a pigment, a dye, and a coloring matter can be used as the lanthanoid coloring agent.

Examples of the oxime-based coloring agent include those having a color index (C.I.; issued by The Society of Dyers and Colourists) having the following colors of green, yellow, orange, red, purple, black, and the like.

- 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

It is also possible to use an anthraquinone coloring agent other than the above, for example, BASF, which is known as a black organic pigment which is transmitted through infrared light, although it is colorless index number. Lumogen (registered trademark) Black FK4280, Lumogen Black FK4281, Lumogen F Yellow 083, Lumogen F Orange 240, Lumogen F Red 305, Lumogen F Green 850, known as concentrating fluorescent dyes, and other lanthanide colorants In the same ultraviolet region, the absorption is small and the coloring power is high, so that it can be suitably used.

(complementary colorant)

Hereinafter, the complementary coloring agent used in combination with the oxime coloring agent in the present invention will be described. First, the complementary color relationship of the present invention will be described.

In the coloring agent, the color of the color index is not exhibited. Therefore, the appearance color of the cured coating film of the photosensitive resin composition is measured and measured according to the method specified in JIS Z8729, and the representative axis L is confirmed by the coordinate axis (see FIG. 4). *a*b* The color a* value and b* value in the color system are selected so that the hardened coating film (a* value, b* value) obtained by the combination with the lanthanide colorant is as close as possible The color former of (0,0) serves as a coloring agent for the complementary color relationship. Here, the film thickness of the cured coating film is not particularly limited as long as it is black.

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

A coloring agent which is related to a complementary color of a lanthanide coloring agent, and a colorimetric a* value of each coloring agent by a combination with a lanthanide coloring agent The coloring agent may be any one of the following, and the coloring agent may be exemplified by any one of the following.

Preferably, the combination with the lanthanide colorant is a combination of Pigment Red 149, 178, 179 and a green lanthanide coloring agent (Solvent Green 3, Solvent Green 20, Solvent Green 28, etc.), if the lanthanide colorants are mixed with each other (combination ) is a combination of a red lanthanide coloring agent (Pigment Red 149, 178, 179) and a black lanthanide coloring agent (Pigment Black 31, 32), a black lanthanide coloring agent (Pigment Black 31, 32) and the same black lanthanide coloring agent. (Lumogen (registered trademark) Black FK4280.4281) combination.

Further, the subsequent layer (A) can be obtained by a combination of a yellow coloring agent and a purple coloring agent, a combination of a yellow coloring agent and a blue coloring agent and a red coloring agent, a combination of a green coloring agent and a purple coloring agent, and a green coloring. Black in any combination of a combination of a red colorant, a yellow colorant, a purple colorant and a blue colorant, and a combination of a green colorant and a red colorant and a blue colorant . Alternatively, a purple colorant, an orange colorant, a brown colorant or the like may be combined.

When the coloring agent of the above complementary color relationship is used, the amount of light absorption is small as compared with the case of containing a black coloring agent. Therefore, in the photosensitive resin composition, even if the content of the coloring agent is increased in order to increase the degree of blackness, the photocuring can be sufficiently performed, and the light sensitivity and the resolution can be improved more than in the case of the black coloring agent. As a result, it can be effectively applied to a flexible printed circuit board having high density and high thinness.

Blue coloring agents are phthalocyanine, lanthanide, etc., and Compounds classified as Pigment, Solvent, and the like. In addition to this, a metal-substituted or unsubstituted phthalocyanine compound can also be used.

The red coloring agent is a monoazo system, a disazo system, an azo lake system, a benzimidazolone system, an anthracene system, a diketopyrrolopyrrole system, a condensed azo system, an anthraquinone system, a quinacridone. Department and so on.

The yellow coloring agent is a monoazo type, a bisazo type, a condensed azo type, a benzimidazolone type, an isoindolinone type, an anthraquinone type, etc.

Green colorants are phthalocyanine and lanthanide. In addition to this, a metal-substituted or unsubstituted phthalocyanine compound can also be used.

A purple coloring agent, an orange coloring agent, and a brown coloring agent, specifically, Pigment Violet 19, 23, 29, 32, 36, 38, 42; Solvent Violet 13, 36; CI pigment orange 1, CI pigment orange 5, CI pigment orange 13, CI pigment orange 14, CI pigment orange 16, CI pigment orange 17, CI pigment orange 24, CI pigment orange 34, CI pigment orange 36, CI pigment orange 38, CI pigment orange 40, CI pigment 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, and the like.

The protective layer (B) may contain a coloring agent, but preferably contains no 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 the components of the protective layer (B) excluding the organic solvent. It is preferably less than 5% by mass, more preferably 4% by mass or less, still more preferably 3% by mass or less.

Since the content of the coloring agent in the protective layer (B) is small, the surface defect portion is not formed, and therefore the insulating property in the Z-axis direction is excellent.

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

The total thickness of the laminated resin structure of the present invention is preferably 100 μm or less, more preferably 4 to 80 μm. For example, when the laminated resin structure is two layers, the subsequent layer (A) is, for example, 3 to 60 μm. By setting such a thickness, the adhesive layer (A) can be adhered to the circuit without a gap. On the other hand, the protective layer (B) is, for example, a thickness of 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 one of a bent portion and a non-bent portion of the flexible printed circuit board, and specifically, a cover layer and a solder for forming a flexible printed circuit board. At least any of the resist layers. Examples of the non-bending portion include a wafer mounting portion and the like.

In the illustrated example, the two-layer structure is not limited to the two layers, and may be three or more layers. However, the outermost layer is set as the protective layer (B).

Fig. 2 is a cross-sectional view showing a state in which the laminated resin structure 1 on the flexible printed circuit board shown in Fig. 1 is formed in a pattern. The pattern formation may be a punching method, a pattern printing method, an imaging method by an organic solvent, or an alkali imaging method depending on the kind of the resin.

As described above, in order to improve the light-shielding property, in the case where the outer layer is blended with carbon black and colored, the breakdown voltage is lowered to cause dielectric breakdown. However, by using the laminated structure as in the present invention, the damage can be prevented. The light resistance is improved satisfactorily by the voltage.

(dry film)

The dry film of the present invention comprises a carrier film (support) and the above-described 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 a carrier film. .

The dry film is produced by diluting the resin composition (B1) with an organic solvent to adjust the viscosity to a suitable viscosity, and coating it to a uniform thickness on a carrier film by a dot coater, and drying to form a protective layer (B). Next, in the same manner, the adhesive layer (B) can be formed on the protective layer (B) by the resin composition (A1) to obtain the dry film of the present invention.

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

(flexible printed circuit board)

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

<Method for Producing Laminated Resin Structure>

The method of forming the adhesive layer (A) and the protective layer (B) on the flexible printed circuit board may be a lamination method using the dry film of the present invention, or may be a direct use of the resin composition (A1), ( Coating method of B1). In the lamination method, the adhesive layer is attached to the flexible printing by contacting the adhesive layer and the non-bending portion of the flexible printed circuit board by a laminator or the like. On the board.

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

Further, the resin composition (A1) may be applied to the flexible printed circuit board, and the adhesive layer (A) may be formed by drying, and the resin composition (B1) may be laminated on the adhesive layer (A). A film, and a method of forming the protective layer (B).

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

<Method of Manufacturing Flexible Printed Circuit Board Using Thermosetting Laminated Resin Structure>

The thermosetting layered resin structure may be a thermosetting resin composition as long as at least one of the resin composition (A1) and the resin composition (B1). For example, by screen printing equal to a flexible printed circuit board The thermosetting resin composition (A1) was applied and dried, and as shown in Fig. 3, a pattern of the adhesive layer (A) was formed. Then, the thermosetting resin composition (B1) is applied by a screen printing method or the like in a pattern corresponding to the pattern of the adhesive layer (A), and dried, and a protective layer is formed as shown in FIG. (B) The pattern. Thereby, the pattern of the thermosetting laminated resin structure is formed.

Next, the thermosetting laminated resin structure is heated at 130 to 200 ° C for 30 to 120 minutes and thermally cured to form a pattern of a protective film.

<Method of Manufacturing Flexible Printed Circuit Board Using Non-Explicit Photosensitive Laminated Resin Structure>

The non-developing type photosensitive laminated resin structure is not limited to any one of the resin composition (A1) and the resin composition (B1).

For example, a non-developing photosensitive resin composition (A1) and a non-developing photosensitive resin composition (B1) are formed on the flexible printed circuit board by the above-described coating method or the like ( A) A non-developing photosensitive laminate resin structure of the protective layer (B). Then, the non-developing photosensitive laminate resin structure is irradiated with light such as ultraviolet rays by a contact type or a non-contact type, and is cured to form a pattern of the cured film. Further, heating may be performed after photohardening, and light irradiation and heating may be simultaneously performed.

<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, at least one of the resin composition (A1) and the resin composition (B1) may contain 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 in the flexible printed circuit board by the lamination method or the like. A negative-type laminated resin structure having an adhesive layer (A) and a protective layer (B) is formed thereon. Then, the negative-type laminated resin structure is irradiated with light in a negative pattern by a contact type or a non-contact type, and the unirradiated portion is developed to form a pattern to obtain a protective film. Further, in the case of a composition containing a thermosetting component, it is thermally cured by heating to a temperature of, for example, about 140 to 180 ° C to form heat resistance, chemical resistance, moisture absorption resistance, and adhesion. A protective film excellent in various properties such as electrical characteristics. Since the negative-type laminated resin structure contains a photopolymerization initiator, the light-irradiated portion is hardened by radical polymerization.

<Method for Producing 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, at least one of the resin composition (A1) and the resin composition (B1) may contain a photobase generator. For example, in the same manner as the method of forming a negative-type laminated resin structure containing a photopolymerization initiator, an underlayer (A) containing a photobase generator and a photobase generator are formed. A negative laminated resin structure of the sheath (B). Then, in the negative-type laminated resin structure, a pattern of a negative-type pattern is irradiated with light to form a base from the photobase generator, and the light-irradiated portion is cured, and the pattern of the protective film is formed by removing the unirradiated portion by development. . Here, it is preferred to heat the laminated resin structure after light irradiation.

Then, after the image is developed, ultraviolet rays are further irradiated to improve the insulation reliability of the protective film. Further, heating (post-hardening) may be performed after development, and ultraviolet irradiation and heating may be simultaneously performed after development.

<Method for Producing Flexible Printed Circuit Board Using Negative Laminated Resin Structure Containing Photoacid Generator>

In the case of a negative-type laminated resin structure containing a photo-acid generator, at least one of the resin composition (A1) and the resin composition (B1) may contain a photo-acid generator. For example, in the same manner as the method of forming a negative-type laminated resin structure containing a photopolymerization initiator, an underlayer (A) containing a photoacid generator and a protective layer (B) containing a photoacid generator are formed. A negative laminated resin structure. Thereafter, the negative-type laminated resin structure is irradiated with light to generate an acid from the photo-acid generator, and the light-irradiating portion is cured. Then, a pattern of the protective film is formed by the same developing method as described above.

<Method of Manufacturing 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, in the same manner as the method of forming a negative-type laminated resin structure containing a photopolymerization initiator, a positive-type adhesive layer (A) and a positive-type protective layer (B) are formed on a flexible printed circuit board. A positive laminated resin structure. Thereafter, the positive-type laminated resin structure is irradiated with light in a pattern. After the light irradiation, the light irradiation portion is removed by the same development method as described above to form a pattern of the protective film.

The exposure machine used for the above-mentioned light irradiation may be a device that emits ultraviolet rays in the range of 350 to 450 nm by using a high-pressure mercury lamp tube, an ultra-high pressure mercury lamp tube, a metal halide lamp, a mercury short-arc lamp, or the like. A rendering device (for example, a laser direct imaging device that draws an image with a direct laser by CAD data from a computer).

The laser light source of the direct drawing machine can be either a gas laser or a solid laser as long as it uses laser light having a maximum wavelength of 350 to 450 nm. The amount of exposure required for image formation varies depending on the film thickness, etc., but generally it can be in the range of 20 to 1500 mJ/cm ² . The development method can be carried out by a liquid-filling method, a shower method, a spray method, a brush method, etc., and the developing solution can be potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium citrate, ammonia, or the like. An aqueous solution of an alkali such as an amine.

[Examples]

Hereinafter, the present invention will be specifically described by showing examples and comparative examples, but the present invention is not limited to the following examples.

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

The components other than the coloring agent and the coloring agent were blended in a ratio (parts by mass) shown in the following Table 1 and mixed with a mixer, and then kneaded by a 3-roll mill to prepare a photosensitive resin composition (A1). ) and a photosensitive resin composition (B1).

(Photosensitive resin composition (A1))

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

Trimethylolpropane EO modified triacrylate (East Asia Synthesis Corporation) System): 16 parts by mass

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

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

Aminoalkylphenol photopolymerization initiator (manufactured 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 type epoxy acrylate (manufactured by DIC): 100 parts by mass

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

Bisphenol A type novolac epoxy resin (made by DIC): 23 parts by mass

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

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

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

(Examples 1, 2, and Comparative Example 4)

The resin composition (B1) is applied onto the carrier film, and after drying to form a protective layer (B), the photosensitive resin composition (A1) is applied onto the surface, and dried to form an adhesive layer (A). 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 was 30 μm, and the thickness of the (B) protective layer was 10 μm.

Next, the laminated resin structure was irradiated with light at an exposure amount of 500 mJ/cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and a protective film was formed by development.

(Comparative examples 1 to 3)

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

Next, the protective layer (B) was irradiated with light at an exposure amount of 500 mJ/cm ² using an exposure apparatus (HMW-680-GW20) equipped with a metal halide lamp, and a protective film was formed by development.

<destruction voltage>

The voltage withstand voltage tester TOS5051A manufactured by Kikusui Electronics Co., Ltd. was used to increase the voltage in the thickness direction (Z-axis direction) of the protective film at 0.5 kV/sec, and the voltage at which conduction was performed was used as the breakdown voltage.

<shading>

For the evaluation substrates on which the protective films of the examples and the comparative examples were formed, the light-shielding property was evaluated by visual observation. The case where the light blocking property is good is regarded as ○, and the case where the light blocking is good is regarded as ×.

According to the results shown in the above Table 1, the protective film obtained from the laminated resin structures of Examples 1 and 2 was high in breakdown voltage on the flexible printed circuit board, and the light-shielding property was good. On the other hand, 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, Comparative Examples 5 to 8)

The components other than the coloring agent and the coloring agent were blended in a ratio (parts by mass) shown in the following Table 2, and mixed with a mixer, and then kneaded by a 3-roll mill to prepare a thermosetting resin composition ( A1) and a thermosetting resin composition (B1). With respect to the obtained Examples 3 and 4 and Comparative Examples 5 to 8, the results of evaluation in the same manner as in the above Example 1 and the like are collectively shown in Table 2 below.

(thermosetting resin composition (A1))

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

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

Novolac type phenol resin (manufactured by Minghe Chemical Co., Ltd.): 25 parts by mass

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

(thermosetting resin composition (B1))

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

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

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

Novolak type phenol resin (made by Minghe Chemicals): 28 parts by mass

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

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

(Examples 3, 4, and Comparative Example 8)

The thermosetting resin composition (A1) was applied to a pattern on a flexible printed circuit board 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 onto the adhesive layer (B) by a screen printing method in a pattern corresponding to the pattern of the adhesive layer (A), and heated at 150 ° C for 60 minutes. Thermally hardened to form a protective layer (B). (A) The thickness of the adhesive layer was 30 μm, and (B) the protective layer (B) was 10 μm.

(Comparative examples 4 to 7)

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

According to the results shown in the above Table 2, the protective film obtained from the laminated resin structures of Examples 3 and 4 was high in breakdown voltage on the flexible printed circuit board and had good light-shielding properties. On the other hand, in Comparative Example 5, the breakdown voltage was low and the light-shielding property was poor, and in Comparative Example 6~ In 8, the result of lowering the voltage is lower.

1‧‧‧Laminated resin structure

2‧‧‧Flexible substrate

3‧‧‧Bronze circuit

A‧‧‧Next layer

B‧‧‧Protective layer

Claims (8)

A laminated resin structure comprising: a laminate layer (A); and a laminated resin structure laminated on the protective layer (B) of the flexible printed circuit board via the adhesive layer (A). The adhesive layer (A) contains a coloring agent other than carbon black. The laminated resin structure according to claim 1, wherein the adhesive layer (A) contains an anthraquinone coloring agent. The laminated resin structure according to claim 1, wherein the adhesive layer (A) is black. The laminated resin structure according to claim 1, wherein the adhesive layer (A) is thicker than the protective layer (B). The laminated resin structure according to any one of claims 1 to 4, which is used for at least one of a bent portion and a non-bent portion of the flexible printed circuit board. The laminated resin structure according to any one of claims 1 to 4, which is used for forming at least one of a coating 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 according to any one of claims 1 to 4 is supported or protected by a film. A flexible printed circuit board comprising a protective film obtained by curing a laminated resin structure according to any one of claims 1 to 4 on a flexible printed circuit board.