KR102066879B1 - Coverlay film - Google Patents

Abstract

An object of this invention is to provide the coverlay film which is excellent in workability and workability, and excellent in followability with respect to a flexible printed circuit board (FPC), although it is a thin film. In order to solve the said subject, the base material 12 and the thermosetting adhesive layer 13 which consist of a thin film resin layer of the apply | coated dielectric material are laminated | stacked in order on one surface of the support film 11, and the The coverlay film 10 characterized by the tensile elongation by the method of JIS-K-7127 is 100% or more.

Description

Coverlay film {COVERLAY FILM}

The present invention relates to a thin coverlay film which covers and protects a flexible printed circuit board (hereinafter referred to as FPC) which is repeatedly subjected to bending operation.

BACKGROUND OF THE INVENTION In portable electronic devices such as mobile phones, electronic components are integrated on a printed board in order to keep the external dimensions of the case small and thin and to make it easy to carry around. In addition, in order to reduce the external dimensions of the case, the printed circuit board is divided into a plurality of sheets, and the printed circuit board is folded or slided by using an FPC having flexibility in connection wiring between the divided printed circuit boards.

In addition, in recent years, portable information terminals (smartphones, tablets, etc.) consume more power than conventional mobile phones, and the battery maintainability is deteriorated. For this reason, it is necessary to enlarge the capacity and capacity of a battery which can be possible, and the size and thickness of members and components other than a battery are strongly demanded.

Furthermore, in recent years, the light-shielding property and the designability are emphasized, and the colored coverlay film is calculated | required.

Conventionally, as a coverlay film used for the purpose of such a thinning, the thing which apply | coated the adhesive agent to the thin polyimide film is used (patent document 1), but a thin polyimide film is bad in processing titration, and workability is affixed to FPC. Was bad. Moreover, in the conventional thin coverlay film, the followability with respect to the step | step of FPC is not enough, a gap was created and it became a cause of problems, such as expansion in a heating process. For this reason, sufficient thickness reduction of FPC was difficult.

In addition, for the purpose of improving light-shielding properties and designability, a coverlay film containing a black pigment in a polyimide film containing a black pigment or a dye, an electrical insulation film, and a thermosetting adhesive or both is proposed ( Patent document 1) and the said thinning are not considered at all.

Japanese Patent Laid-Open No. 9-135067

In view of the background art, the present invention provides a coverlay film having excellent processing suitability and workability and excellent followability to FPC despite being a thin film.

In order to improve the handleability, in the present invention, a substrate made of a thin film of dielectric resin and an adhesive layer are sequentially stacked on one surface of the support film. Moreover, after laminating | stacking and adhesive-bonding an adhesive bond layer to FPC, it can transfer to FPC by peeling a support film.

In addition, in order to withstand excessive bending and to improve the followability to FPC, the present invention uses a substrate made of a thin film of dielectric resin having high tensile elongation. In this invention, it is technical idea to manufacture the laminated body which laminated | stacked the adhesive bond layer on the base material which consists of at least the thin film resin layer of a dielectric material.

In addition, in the present invention, as a base material composed of a thin film of a dielectric resin, in consideration of flexibility, using the thin film resin layer of the coated dielectric, the thickness of the entire coverlay film except the support film and the release film is reduced to 15 μm or less. It is possible.

In the present invention, the adhesive layer bonded to the FPC is used as a thermosetting resin layer, and an adhesive layer is formed between the substrate and the thermosetting adhesive layer in order to increase the adhesion between the substrate made of a thin film resin layer such as polyimide and the thermosetting resin layer. You may.

Moreover, in this invention, in order to solve the said problem, the base material which consists of a thin film resin layer of the apply | coated dielectric material, and the thermosetting adhesive bond layer is laminated | stacked in order on one surface of a support film, and according to JIS-K-7127 of the said base material The tensile elongation by a method is 100% or more, The coverlay film is provided.

Moreover, in this invention, in order to solve the said problem, the base material which consists of a thin film resin layer of the apply | coated dielectric material, the thin film adhesive bond layer, and the thermosetting adhesive bond layer is laminated | stacked in order on one side of the support film, JIS of the said base material The coverlay film which is 100% or more of tensile elongation by the method of -K-7127 is provided.

It is preferable to contain a light absorbing agent in at least one of the said base material, the thin film adhesive bond layer, and a thermosetting adhesive bond layer.

It is preferable that the said base material consists of an insulating layer formed using the solvent soluble polyimide, and is 1-9 micrometers in thickness.

The light absorber which the said base material consists of at least 1 type of black pigment selected from the group which consists of nonelectroconductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide, or a color pigment. It is preferable to include.

At least one black pigment selected from the group consisting of non-conductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide, or at least one of colored pigments. It is preferable to include the light absorbing agent which consists of.

It is preferable that the said thermosetting adhesive layer is a flame-retardant thermosetting adhesive which contains a flame-retardant phosphorus containing polyurethane resin and an epoxy resin.

The thermosetting adhesive layer comprises at least one black pigment selected from the group consisting of non-conductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide, or at least one of colored pigments. It is preferable to include a light absorbing agent.

Moreover, this invention provides the mobile telephone in which the said coverlay film is used as an FPC protection member.

Moreover, this invention provides the electronic device by which the said coverlay film is used as an FPC protection member.

According to the coverlay film of the present invention, by using a base material made of a thin film resin having a high tensile elongation and proper tensile strength, the wiring board having a step and the like is followed without a gap, and the subsequent solder reflow process and In processes, such as a plating process, a thin film coverlay film which does not generate | occur | produce a problem by expansion and penetration of a plating liquid can be manufactured.

Moreover, by using the thin film resin film (1-9 micrometers in thickness) of the polyimide film which has insulation as a base material, it becomes possible to have the outstanding bending characteristic which can endure excessive bending operation. For this reason, the total thickness of the coverlay film except a support film and a peeling film can be suppressed to 15 micrometers or less, and it can contribute to thinning the total thickness of a mobile telephone and an electronic device.

By mixing the light absorbing agent which consists of 1 or more types of black pigment or a colored pigment in a base material or an adhesive bond layer, specific coloring is attained to one surface side of a coverlay film.

According to the present invention, according to the present invention, in a heating step such as a solder reflow step after coating a wiring board or the like, it is a thin, flexible, rich flexible type that does not cause problems due to expansion or penetration of the plating liquid, and excessive bending operation is repeated. Even if it does, the coverlay film excellent in the bending characteristic which does not produce the fall of FPC protection performance can be provided.

1 is a schematic cross-sectional view showing a first embodiment of a coverlay film according to the present invention.
It is a schematic sectional drawing which shows 2nd Embodiment of the coverlay film which concerns on this invention.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described. This invention is not limited to this embodiment, A various change is possible in the range which does not deviate from the summary of this invention. This embodiment includes the following first and second embodiments.

When the coverlay film of this embodiment is bonded to FPC etc. which are to-be-adhered bodies, the outer surface is a dielectric and can protect electrically wiring, circuit components, etc. of an FPC. In addition, the coverlay film of this embodiment makes the whole thickness thin in order to improve the bending characteristic with respect to a bending operation | movement.

In the coverlay film 10 of the first embodiment shown in FIG. 1, the base material 12 has flexibility, has a thickness of 1 to 9 µm and a tensile elongation of 100% or more, for example, a solvent-soluble poly Thin film resin films, such as a polyimide film formed using the mead, are mentioned. In addition, the support film 11 is laminated | stacked on one surface of the base material 12, and the adhesive bond layer 13 is laminated | stacked on the other surface of the base material 12. As shown in FIG. The adhesive layer 13 is an electrically insulating adhesive layer bonded to the surface of the FPC, for example, a thermosetting adhesive layer. On the surface of the adhesive layer 13, a release film 19 for protecting the adhesive layer 13 can be laminated. The coverlay film 10 can be used as the coverlay film 15 having a structure in which the support film 11 and the release film 19 are removed and the adhesive layer 13 is laminated on one side of the substrate 12. have. In 1st Embodiment, the adhesive bond layer 13 may be in contact with one side of the base material 12.

In the coverlay film 20 of 2nd Embodiment shown in FIG. 2, as the base material 12, it has flexibility, thickness is 1-9 micrometers, and tensile elongation is 100% or more, For example, solvent-soluble poly is Thin film resin films, such as a polyimide film formed using the mead, are mentioned. In addition, the support film 11 is laminated | stacked on one surface of the base material 12, and the adhesive bond layer 14 and the adhesive bond layer 13 are laminated | stacked on the other surface of the base material 12 in order. The adhesive layer 14 is a thin film adhesive layer which improves the adhesive force between the adhesive layer 13 and the base material 12. The adhesive layer 13 is an electrically insulating adhesive layer bonded to the surface of the FPC, for example, a thermosetting adhesive layer. On the surface of the adhesive layer 13, a release film 19 for protecting the adhesive layer 13 can be laminated. This coverlay film 20 removes the support film 11 and the peeling film 19, and as a coverlay film 16 of the structure by which the adhesive layers 13 and 14 were laminated | stacked on one side of the base material 12. Can be used. In 2nd Embodiment, the adhesive bond layer 13 may be in contact with the adhesive bond layer 14, and the adhesive bond layer 14 may be in contact with one side of the base material 12. As shown in FIG.

(materials)

The base material 12 of the coverlay films 10, 15, 16, and 20 according to the present embodiment is an insulating layer made of a thin film resin layer of a dielectric. Since the thin film resin film of the polyimide film formed using the solvent-soluble polyimide has high mechanical strength, heat resistance, insulation, and solvent resistance, which are characteristic of the polyimide resin, and is considered to be chemically stable up to about 260 ° C, the substrate 12 Preferred as

Examples of the polyimide include thermosetting polyimides resulting from the dehydration condensation reaction upon heating of the polyamic acid, and solvent-soluble polyimides soluble in non-dehydration condensation solvents.

A method generally known as a method for producing a general polyimide film synthesizes a polyamic acid, which is an imide precursor, by reacting diamine and carboxylic dianhydride in a polar solvent, and dehydrating the polyamic acid by using heat or a catalyst. To obtain a corresponding polyimide. However, in this step of imidizing, the temperature of the heat treatment is considered to be preferably in the range of 200 ° C to 300 ° C, and if the heating temperature is lower than this temperature, imidization may not proceed, which is not preferable. If the heating temperature is higher than the above temperature, thermal decomposition of the compound may occur, which is considered to be undesirable.

The coverlay films 10, 15, 16, and 20 of the present embodiment are intended to further improve the flexibility of the substrate 12, and use an extremely thin polyimide film having a thickness of less than 10 µm.

In this embodiment, both the base material formed by laminating | stacking a thin polyimide film on one side of the support film 11 used as a reinforcement material of strength, or the base material which consists only of a thin polyimide film without using the support film 11 can be used. Can be.

When the thickness of the polyimide film used is thinner than about 7 micrometers, it is preferable to laminate | stack and form a thin polyimide film on one side of the support film 11 used as a reinforcement material on strength. For example, the coating liquid containing a polyamic acid can be cast on one side of the support film 11, and can be heated to form a polyimide.

By the way, although the polyimide film itself has heat resistance with respect to the heat processing in the heating temperature of 200 degreeC-250 degreeC, as a support film 11, the general purpose heat resistant resin film, for example, polyethylene from the balance of price and heat resistance temperature performance When using films with low heat resistance, such as a terephthalate (PET) resin film, the method of forming a polyimide from the polyamic acid which is a conventional imide precursor cannot be employ | adopted.

Since the solvent-soluble polyimide has completed the imidation of the polyimide, and is soluble in a solvent, it can form into a film by apply | coating the coating liquid dissolved in the solvent, and volatilizing a solvent at low temperature below 200 degreeC. For this reason, after the base material 12 used for the coverlay film of this embodiment apply | coats the coating liquid of solvent-soluble polyimide which is a non-dehydration condensation type | mold on one surface of the support film 11, heating temperature is less than 200 degreeC. It is preferable to dry at the temperature and to form the thin film resin film of the polyimide film formed using the solvent soluble polyimide. By doing in this way, the ultrathin polyimide film of thickness 1-9 micrometers can be laminated | stacked on one surface of the support film 11 which consists of a general-purpose heat resistant resin film. By forming the base material 12 by application | coating (coating) similarly to the adhesive bond layers 13 and 14, the base material 12 and the adhesive bond layer 13 on it, conveying the support film 11 along the longitudinal direction. , 14) and the like can be formed continuously, so that production from roll to roll is possible, and workability and productivity are excellent.

Although the solvent-soluble polyimide which is a non-dehydration condensation type which can be used for the base material 12 of this embodiment is not specifically limited, It is possible to use the coating liquid of the commercially available solvent-soluble polyimide. As a coating liquid of the commercially available solvent-soluble polyimide, specifically, Sorfi 6,6-PI (Sorpy Industries), Q-IP-0895D (Phi-Tech Institute), PIQ (Hitachi Chemical Co., Ltd.), SPI-200N ( Shin-Nitetsu Chemical Co., Ltd., Rika-Cote SN-20, Rika-cote PN-20 (Shin-Nippon Chemical), etc. are mentioned. The method of apply | coating the coating liquid of solvent soluble polyimide on the support film 11 is not restrict | limited, For example, it can apply | coat with a coater, such as a die coater, a knife coater, a lip coater.

It is preferable that the thickness (for example, thickness of a polyimide film) of the base material 12 of this embodiment is 1-9 micrometers. It is technically difficult to form the thickness of a polyimide film below 0.8 micrometer in the point that the mechanical strength of the film formed into a film is weak. Moreover, when the thickness of the base materials 12, such as a polyimide film, exceeds 10 micrometers, it will become difficult to obtain the coverlay films 15 and 16 which are thin and have the outstanding bending performance.

In addition, when the thickness of the polyimide film used is thinner than about 7 micrometers, since the tension adjustment at the time of winding up on a roll is difficult, a thin polyimide film is laminated | stacked on one side of the support film 11 used as a reinforcement material on strength. It is preferable that it is formed.

It is preferable that the thickness in the case of using the base material 12 which consists only of a thin polyimide film, without using the support film 11 is about 1-9 micrometers.

In addition, it is preferable that the base material 12 of this embodiment has high tensile elongation in order to improve the followability to FPC. 100% or more is preferable and, as for the tensile elongation of the base material 12, 250% or less is preferable. It is preferable that the elasticity modulus of the base material 12 is 1.0 GPa or more and 2.5 GPa or less. When the base material 12 with high tensile elongation is comprised with a polyimide film, it is preferable to use the polyimide material which has an aliphatic unit of 3 or more carbon atoms between aromatic units, for example. Furthermore, it is preferable that an aliphatic unit contains the polyalkylene oxy group which has a C1-C10 alkylene group.

The tensile elongation of a base material is measured as a tensile strain of plastics based on the base material of JIS-K-7127. The elasticity modulus of a base material is measured as the tensile elasticity modulus of plastics based on the base material of JIS-K-7161.

Moreover, it is preferable that the water vapor permeability of the polyimide film used for the base material 12 of this embodiment is 500 g / m <2> * day or more. If the water vapor permeability is lower than 500 g / m 2 · day, the heating process such as solder reflow after coating the FPC causes the occurrence of rapid heating of the outgas from the residual solvent or adhesive in each layer and the moisture in the film. Each layer may be peeled off by water vapor. There is no particular upper limit to the water vapor permeability, but as long as the same material is used, the water vapor permeability is inversely proportional to the thickness. Therefore, when the thickness is made thin, the water vapor permeability is preferably included in the above-described thickness range.

(Support film)

As a base material of the support film 11 used for this embodiment, polyester films, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films, such as polypropylene and polyethylene, are mentioned, for example. have.

When the base material of the support film 11 has some peelability to the base material itself, such as polyethylene terephthalate, for example, the thin film of the dielectric material directly apply | coated without performing peeling process on the support film 11 The base material 12 which consists of a resin film may be laminated | stacked, and the peeling process for making it easier to peel the base material 12 may be performed on the surface of the support film 11.

In addition, when the base film used for the said support film 11 does not have peelability, peeling process is performed by apply | coating peeling agents, such as an amino alkyd resin and a silicone resin, and heat-drying. Since the coverlay films 10, 15, 16, and 20 of this embodiment are bonded to an FPC, it is preferable that a silicone resin is not used for this peeling agent. Because, when the silicone resin is used as the release agent, a part of the silicone resin is transferred to the surface of the base material 12 in contact with the surface of the support film 11, and through the inside of the coverlay films 10, 15, 16, 20. There exists a possibility that it may further transfer to the surface of the adhesive bond layer 13 from the base material 12. This is because the silicone resin transferred to the surface of the adhesive layer 13 may weaken the adhesive force of the adhesive layer 13.

Although the thickness of the support film 11 used for this embodiment is excluded from the thickness of the whole coverlay films 15 and 16 at the time of coating and using FPC, it is not specifically limited, Usually, it is about 12-150 micrometers. By using the support film 11, the workability at the time of forming the base material 12 and the adhesive bond layers 13 and 14 and the workability at the time of bonding to FPC can be improved.

Color of the support film 11 may be colorless (colorless) or may be colored. When coloring on the support film 11, it is preferable that an index with a large contrast with respect to the color of the coverlay films 15 and 16 except the support film 11 and the peeling film 19 is preferable. For example, when the coverlay films 15 and 16 have a dark index such as black, the support film 11 is preferably a bright index such as white or yellow. For this reason, the handleability, such as peeling the coverlay films 15 and 16 from the support film 11, and the checkability of whether the support film 11 is peeling off can be improved. Coloring of the support film 11 can be performed using a well-known pigment, dye, etc. As the support film 11, the white PET film whose thickness is 30 micrometers or more and 60 micrometers or less is mentioned, for example.

(Thermosetting adhesive layer)

The coverlay films 10, 15, 16, and 20 according to the present embodiment are preferably the thermosetting adhesive layers as the adhesive layers 13 bonded to the FPC. As a thermosetting adhesive used for the adhesive bond layer 13, thermosetting adhesives generally used, such as an acrylic adhesive, a polyurethane adhesive, an epoxy adhesive, a rubber adhesive, and a silicone adhesive, are mentioned. Moreover, what mix | blended flame retardants, such as phosphorus type and bromine type, and made it flame-retardant is used preferably, but it does not specifically limit. A phosphorus-containing polyurethane may be used as the thermosetting adhesive in the molecular structure of the resin by using a phosphorus-containing compound as a polyol compound or polyisocyanate compound serving as a polyurethane raw material. It is preferable that the thermosetting adhesive layer 13 contains a phosphorus containing polyurethane resin composition and an epoxy resin.

As for the thickness of the thermosetting adhesive layer 13, 1-8 micrometers is preferable, for example. The thermosetting adhesive layer 13 can be formed by application | coating, for example. When the thermosetting adhesive layer 13 contains a flame retardant, flame retardancy can be imparted to the coverlay films 15 and 16 except for the support film 11 and the release film 19 without adding a flame retardant to the substrate 12. have.

Although the adhesive force of a thermosetting adhesive does not have a restriction | limiting in particular, The measuring method is 5-1 N in Method A (90 degree-direction peeling) of 8.1.1 of JIS-C-6471 "Testing method of copper clad laminated board for flexible printed wiring boards". A range of / inch is preferred. If the adhesive force is less than 5N / inch, for example, the coverlay films 15 and 16 bonded to the FPC may be peeled off or lifted off by heat or bending.

If the thermosetting adhesive is not an adhesive showing pressure-sensitive adhesiveness at room temperature but an adhesive by heat and pressure, the adhesive force is less likely to decrease with repeated bending, which is preferable. Although the conditions of heat-pressure adhesion to FPC are not specifically limited, For example, it is preferable to heat-press for 60 minutes with 160 degreeC of temperature and 4.5 MPa of pressurization pressures. When heat-pressurizing the coverlay films 15 and 16 except the support film 11 and the peeling film 19 with respect to FPC, the support film 11 may be removed from the coverlay films 15 and 16, It is also possible to heat pressurize including the support film 11.

(Adhesive layer)

In order to improve the adhesive force of the adhesive bond layer 14 used for the coverlay films 16 and 20 of 2nd Embodiment, a thin film, such as a polyimide film which is the base material 12, and the adhesive bond layer 13 which is a thermosetting adhesive bond layer, It is formed as an anchor layer. As shown in the first embodiment, the adhesive layer 14 can be omitted.

Since the adhesive temperature by heat-pressing of the thermosetting adhesive bond layer 13 laminated | stacked on it is 150-250 degreeC, it is preferable to use the adhesive agent excellent in heat resistance. Moreover, it is preferable that it is excellent in the adhesive force with respect to the insulating resin, such as the polyimide film used as the base material 12, and the thermosetting adhesive bond layer 13. As shown in FIG.

As an adhesive resin composition used for the adhesive bond layer 14, Preferably thermoplastic resin, such as a polyester resin, a polyurethane resin, a (meth) acrylic resin, a polyethylene resin, a polystyrene resin, a polyamide resin, is used. Moreover, thermosetting types, such as an epoxy resin, an amino resin, a polyimide resin, and a (meth) acrylic resin, may be sufficient.

Especially preferable as adhesive resin composition of the adhesive bond layer 14 is the adhesive resin composition which crosslinks the polyester resin composition which has an epoxy group, and the adhesive resin composition which mixed epoxy resin as a hardening | curing agent to polyurethane resin. For this reason, the adhesive bond layer 14 has harder physical properties than the base material 12 which consists of thin films, such as a polyimide film. Although the polyester resin composition which has an epoxy group is not specifically limited, For example, with the epoxy resin (its uncured resin) which has two or more epoxy groups in 1 molecule, and the polyhydric carboxylic acid which has 2 or more carboxyl groups in 1 molecule, It can obtain by reaction etc. As crosslinking of the polyester resin composition which has an epoxy group, the crosslinking agent for epoxy resins which react with an epoxy group can be used.

It is preferable that the thickness of the adhesive bond layer 14 is about 0.05-1 micrometer, and sufficient adhesive force with the thermosetting adhesive bond layer 13 will be acquired as it is a film thickness of this grade. When the thickness of the adhesive bond layer 14 is 0.05 micrometer or less, there exists a possibility that the adhesive force of the base material 12 and the thermosetting adhesive bond layer 13 may fall. Moreover, even if the thickness of the adhesive bond layer 14 exceeds 1 micrometer, since it is ineffective in the increase in the adhesive force with respect to the base material 12 and the thermosetting adhesive bond layer 13 which consist of a polyimide film, etc., the adhesive layer 14 of the It is not preferable that the thickness exceed 1 μm because the cost increases. The adhesive bond layer 14 can be formed by application | coating, for example.

(Light absorber)

The coverlay films 15 and 16 except for the support film 11 and the release film 19 in order to impart light shielding properties to the coverlay films 15 and 16 in the state bonded to the FPC or to improve designability. The light absorbing agent may be included in any of the layers constituting the same. The layer which may include a light absorbing agent for this purpose is the substrate 12, the thermosetting adhesive layer 13, or any layer that can be formed between the substrate 12 and the thermosetting adhesive layer 13, for example At least any one layer or two or more layers of the base material 12, the thermosetting adhesive layer 13, and the adhesive layer 14 may be mentioned. Examples of the light absorbing agent include at least one black pigment or colored pigment selected from the group consisting of nonconductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide. It is preferable that the kind, compounding quantity, etc. of a light absorber are selected so that the layer containing a light absorber can maintain electrical insulation.

In 1st Embodiment shown in FIG. 1, the light absorbing agent can be mix | blended with either or both of the base material 12 and the thermosetting adhesive bond layer 13. As shown in FIG. The light absorbing agent may be blended only with the base material 12, the light absorbing agent may be blended only with the thermosetting adhesive layer 13, and the light absorbing agent may be blended with the base material 12 and the thermosetting adhesive layer 13.

In 2nd Embodiment shown in FIG. 2, the light absorbing agent can be mix | blended with any one layer or two or more layers of the base material 12, the adhesive bond layer 14, and the thermosetting adhesive bond layer 13. As shown in FIG. For example, a light absorbing agent may be blended in the thermosetting adhesive layer 13 and the adhesive layer 14, a light absorbing agent may be blended in the base material 12 and the adhesive layer 14, and the light absorbing agent only in the adhesive layer 14. May be blended, the light absorbing agent may be blended with the entire layer of the substrate 12, the adhesive layer 14, and the thermosetting adhesive layer 13, the light absorbing agent may be blended only with the substrate 12, and the thermosetting adhesive layer 13 ), A light absorbent may be blended, or the light absorber may be blended into the substrate 12 and the thermosetting adhesive layer 13.

5% or less of the light transmittance of the coverlay films 15 and 16 except the support film 11 and the peeling film 19 is preferable. As light transmittance, visible light transmittance, total light transmittance, etc. are mentioned. When the base material 12 is comprised from solvent soluble polyimide, the base material 12 containing a light absorbing agent can be formed.

In order to reduce light transmittance effectively and to improve light-shielding property, black pigments, such as carbon black, are preferable among light absorbers. It is preferable to contain the light absorbing agent which consists of a black pigment or a coloring pigment in 0.1 to 30weight% in any layer. It is preferable that the black pigment or colored pigment is about 0.02-0.1 micrometer in average particle diameter of a primary particle by SEM observation. The thickness of the layer containing the light absorbing agent is preferably larger than the particle size of the light absorbing agent so that the fine particles of the light absorbing agent are not exposed.

In addition, as a black pigment, only a surface layer part may be made black by immersing a silica particle etc. in a black color material, and may be made with black coloring resin etc., and may be made black as a whole. In addition to the deep black, the black pigment may be used as long as it contains a particle having a color close to black such as gray, black brown, or black green, and is a dark color that is hard to reflect light.

(Peel film)

As described above, the coverlay films 10 and 20 may have a release film 19 to protect the thermosetting adhesive layer 13. As a base material of the peeling film 19, polyester films, such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films, such as polypropylene and polyethylene, are mentioned, for example. After apply | coating release agents, such as an amino alkyd resin and silicone resin, to these base films, a peeling process is performed by heating and drying. Since the coverlay films 10, 15, 16, and 20 of this embodiment are bonded to FPC in the state which removed the peeling film 19, it is preferable that a silicone resin is not used for this peeling agent. When the silicone resin is used as the release agent, part of the silicone resin is transferred to the surface of the thermosetting adhesive layer 13 in contact with the surface of the release film 19, which may weaken the adhesive force of the thermosetting adhesive layer 13. Because. Although the thickness of the peeling film 19 used for this embodiment is excluded from the total thickness of the coverlay films 15 and 16 at the time of coating and using FPC, it is not specifically limited, Usually, it is about 12-150 micrometers.

(Coverlay film)

The coverlay films 10, 15, 16, and 20 of the present embodiment can be suitably used as coverlay films having excellent bending characteristics, which can be used by bonding to FPCs subjected to repeated bending operations. Moreover, the coverlay film of this embodiment can be used for various electronic devices, such as a mobile telephone, a notebook computer, a portable terminal, as a member for FPC protection. In the manufacturing method of the coverlay films 10, 15, 16, and 20 of this embodiment, the base material 12 and the adhesive bond layers 13 and 14 are placed on the support film 11 from the side close to the support film 11; The method of laminating | stacking by apply | coating a material sequentially is mentioned.

15 micrometers or less are preferable for the thickness of the whole coverlay films 15 and 16 except the support film 11 and the peeling film 19, For example, 5-15 micrometers, 12 micrometers or less are mentioned. The thickness of the coverlay films 15 and 16 is the sum of the thicknesses of the base material 12 and the thermosetting adhesive layer 13 in the case of the first embodiment, and in the case of the second embodiment, the base material 12 and the adhesive layer ( 14) is the sum of the thicknesses of the thermosetting adhesive layers 13.

Example

Hereinafter, an Example demonstrates this invention concretely.

(Example 1)

A 50-micrometer-thick polyethylene terephthalate (PET) film which performed the peeling process to one side was used as the support film 11. The base material which consists of a thin film resin film of a dielectric material 12 is cast and dried by apply | coating the coating liquid of the solvent-soluble polyimide whose tensile elongation after drying is 170% on one side of this support film 11 so that thickness after drying may be set to 4 micrometers. ) Was laminated. After drying using the coating liquid for forming the adhesive layer 14 which mixed non-conductive carbon black and the polyester-based resin composition whose heat-resistant temperature is 260-280 degreeC as a black pigment of a light absorber on the formed base material 12, It applied so that thickness might be 1 micrometer, and the adhesive bond layer 14 was laminated | stacked. To 100 parts of phosphorus containing polyurethane resin solution (Toyobo make: UR3575) on the adhesive bond layer 14, 2.4 parts of polyfunctional epoxy resins (Toyobo make: HY-30), 4.7 parts of fumed silica (Nihon Aerosil make: R972) The thermosetting adhesive formed by adding and stirring was sequentially applied and dried so that the thickness after drying might be set to 6 micrometers, the thermosetting adhesive layer 13 was formed, and the coverlay film of Example 1 was obtained.

(Example 2)

A coverlay film of Example 2 was obtained in the same manner as in Example 1 except that the non-conductive carbon black was mixed with the thermosetting adhesive to form the thermosetting adhesive layer 13.

(Example 3)

The adhesive layer 14 is formed without adding non-conductive carbon black to the coating liquid for forming the adhesive layer 14, and non-conductive carbon black is added to the coating liquid of solvent-soluble polyimide, and the base material 12 is formed. A coverlay film of Example 3 was obtained in the same manner as in Example 1 except for one.

(Example 4)

The nonconductive carbon black is added to the coating liquid of solvent-soluble polyimide of 120% of tensile elongation after drying, the base material 12 is formed, the adhesive layer 14 is omitted, and a thermosetting adhesive layer directly on the base material 12 ( Except having formed 13), it carried out similarly to Example 1, and obtained the coverlay film of Example 4.

(Comparative Example 1)

Without using the support film 11, a polyimide film made of a thermosetting polyimide (without Tg) having a thickness of 10 µm is used as the substrate 12, and a non-conductive carbon black is mixed with a thermosetting adhesive to form a thermosetting adhesive layer ( Except having formed 13), it carried out similarly to Example 1, and obtained the coverlay film of the comparative example 1.

(Comparative Example 2)

Without using the support film 11, a polyimide film made of a thermosetting polyimide (without Tg) having a thickness of 12.5 μm is used as the substrate 12, and a non-conductive carbon black is mixed with a thermosetting adhesive to form a thermosetting adhesive layer ( Except having formed 13), it carried out similarly to Example 1, and obtained the coverlay film of the comparative example 2.

(Example 5)

The base material 12 was formed using the coating liquid of the solvent soluble polyimide whose elasticity modulus is 3.2 GPa, and it carried out similarly to Example 1 except having formed the thermosetting adhesive layer 13 using the polyurethane resin which does not contain phosphorus, The coverlay film of Example 5 was obtained.

(Example 6)

The base material 12 is formed using the coating liquid of solvent soluble polyimide whose tensile elongation after drying is 120%, and elasticity modulus is 9.1 GPa, and nonconductive carbon black is not added to the coating liquid for forming the adhesive bond layer 14. Except having provided the adhesive bond layer 14, it carried out similarly to Example 1, and obtained the coverlay film of Example 6.

(Evaluation method of followability)

The thermosetting adhesive surface of the coverlay film was superimposed on a test pattern in which a copper wiring pattern having a thickness of 75 μm and L / S = 75 μm / 75 μm was formed on a polyimide film having a thickness of 12.5 μm, and the temperature was 140 ° C. and the speed was 1 m /. Laminated by thermal lamination in min. After peeling the support film 11, it heat-pressed on the conditions of 160 degreeC, 4.5 Mpa, and 65 minutes, and obtained the followability evaluation sample. When the cross section of the obtained sample was observed and following the wiring pattern, "(circle)" and the case where it does not follow and lifted by the wiring pattern were made into "x".

(Evaluation method of concealment)

The coverlay film obtained was heat-pressed to the test pattern (refer to the followability evaluation method) which formed the above-mentioned copper wiring pattern by the method (refer to the followability evaluation method) mentioned above, and the concealability evaluation sample was obtained. When the difference in concealability is not observed about the polyimide part and copper wiring part (especially the edge part) of the obtained sample, when a part where "(circle)" and a copper wiring end part is seen through and a part where a difference is observed is generated, "Δ" and most of the copper wiring edge portions were visible, and the difference was observed as "x". In addition, Example 6 in which neither layer contained the light absorbing agent was evaluated.

(Evaluation method of flame retardancy)

The obtained coverlay film was heat-pressed to the polyimide film which is 12.5 micrometers in thickness by the method (refer to the evaluation method of followability) mentioned above, and the sample for evaluation of flame retardance was obtained. The flame retardancy was evaluated according to the UL-94 thin material vertical combustion test (ASTM D4804) method, and when the flame retardancy was equivalent to VTM-0, "○" and the flame retardance (non-VTM-2 non-compliance) were "x". Was made.

(Evaluation method of handling)

When the obtained coverlay film was sampled at 50 cm in all directions and superimposed on the flexible printed wiring board, the alignment could be performed quickly, and the case where handling was satisfactory was taken as "○", and it took time to align and wrinkle, The case where handleability was inferior was made into "x".

(Evaluation method of heat resistance)

The obtained coverlay film was heat-pressed to the 25-micrometer-thick polyimide film by the method (refer to the evaluation method of followability) mentioned above, and the sample for evaluation of heat resistance was obtained. The test piece was cut out to the dimension of 2.5 cm x 3 cm, immersed in 290 degreeC solder bath for 10 second, and pulled up. The external appearance of the coverlay film after solder bath immersion was observed visually to see if there were any abnormalities such as lifting, deformation, and wrinkles.

(Test result)

About Examples 1-6 and Comparative Examples 1-2, the coverlay film was evaluated by said evaluation method, and the obtained evaluation result was shown to Tables 1-2. In the column of the material of the heat adhesive adhesive layer, "PU1" means the heat adhesive adhesive containing the flame-retardant polyurethane used in Example 1, and "PU2" means the heat adhesive containing the polyurethane used in Example 5 Means sex adhesive. What is written as "none" in the column of thickness means that it does not have the layer.

According to the evaluation result shown to Table 1, Table 2, when the tensile elongation of the base material 12 is 100% or more, it turns out that a followability and heat resistance become favorable. That is, when the tensile elongation of the base material 12 is low, the followability to a level | step difference deteriorated, and abnormality generate | occur | produced at the time of heat resistance evaluation.

Moreover, according to Examples 1-4 and 6, the flame retardant was mix | blended with the thermosetting adhesive bond layer 13, and it was able to ensure favorable flame retardance even if it does not mix | blend a flame retardant with the base material 12.

Moreover, according to Examples 1-6, since the thickness increased with the support film, the handleability at the time of bonding to a flexible wiring board improved, and since the support film 11 can be removed before or after heat press, work efficiency The improvement and the thickness reduction of both became possible.

Moreover, according to Examples 1-5, the light-shielding property and designability could be improved effectively by including a light absorbing agent in at least one layer of a base material, a thin film adhesive bond layer, and a thermosetting adhesive bond layer.

The coverlay film of this invention can be used as a protective member of FPC for various electronic devices, such as a mobile telephone, a notebook computer, and a portable terminal.

10, 15, 16, 20... Coverlay film, 11... Support film, 12... Substrate, 13, 14... Adhesive layer, 19... Release film.

Claims (8)

On one side of the support film, the base material and the thermosetting adhesive layer which consist of a thin film resin layer of the apply | coated dielectric material are laminated | stacked in order,
Tensile elongation by the method of JIS-K-7127 of the said base material is 100% or more,
The thermosetting adhesive layer comprises a phosphorus-containing polyurethane resin composition and an epoxy resin,
Said base material is a polyimide film formed using the polyimide which has a C3 or more aliphatic unit containing a polyalkyleneoxy group which has a C1-C10 alkylene group between aromatic units, The coverlay film characterized by the above-mentioned. On one surface of the support film, a base material consisting of a thin film resin layer of the applied dielectric, an adhesive layer of a thin film, and a thermosetting adhesive layer are laminated in this order,
Tensile elongation by the method of JIS-K-7127 of the said base material is 100% or more,
The thermosetting adhesive layer comprises a phosphorus-containing polyurethane resin composition and an epoxy resin,
Said base material is a polyimide film formed using the polyimide which has a C3 or more aliphatic unit containing a polyalkyleneoxy group which has a C1-C10 alkylene group between aromatic units, The coverlay film characterized by the above-mentioned. The method of claim 2,
The coverlay film containing a light absorber in at least one of the said base material, the thin film adhesive bond layer, and a thermosetting adhesive bond layer. The method according to claim 1 or 2,
The said base material consists of an insulating layer formed using the solvent soluble polyimide, The coverlay film characterized by the above-mentioned. The method according to claim 1 or 2,
The light absorber which the said base material consists of at least 1 type of black pigment selected from the group which consists of nonelectroconductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide, or a color pigment. Coverlay film comprising a. The method of claim 2,
The adhesive layer of the thin film is at least one black pigment selected from the group consisting of non-conductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide, or at least one color pigment. A coverlay film comprising a light absorbing agent made. The method according to claim 1 or 2,
The thermosetting adhesive layer is formed of at least one black pigment selected from the group consisting of non-conductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, and manganese oxide, or at least one of colored pigments. A coverlay film comprising a light absorber. The electronic device in which the coverlay film of Claim 1 or 2 is used as an FPC protection member.

Images