KR101987646B1 - Coverlay film - Google Patents

Abstract

Disclosure of the Invention The present invention aims to provide a coverlay film having good processability and workability and excellent followability to a flexible printed board (FPC) despite being a thin film. A substrate 12 made of a thin dielectric resin layer and a thermosetting adhesive layer 13 are stacked in this order on one surface of a support film 11, And a tensile elongation according to the method of JIS-K-7127 is 100% or more.

Description

COVERLAY FILM

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

BACKGROUND ART In a portable electronic device such as a cellular phone, electronic components are integrated on a printed board in order to make the size of the casing small and thin and easy to carry. Further, in order to reduce the external dimensions of the case, a printed board is divided or slid by dividing the printed board into a plurality of pieces and using flexible FPCs as connection wirings between the divided printed boards.

In addition, recent portable information terminals (such as smartphones and tablets) consume more electric power than conventional cellular phones, so that the retention of the batteries deteriorates. For this reason, it is necessary to increase the capacity and capacity of a battery as much as possible, and it is strongly desired to reduce the size and thickness of members and components other than the battery.

Furthermore, in recent years, a light-shielding film and a decorative film have been emphasized, and a colored coverlay film is required.

Conventionally, as a coverlay film used for such a thinning purpose, a thin polyimide film coated with an adhesive is used (Patent Document 1), but a thin polyimide film has poor workability and has workability when affixed to an FPC It was bad. In addition, in the conventional thin coverlay film, the trackability to the step difference of the FPC is not sufficient and a gap is formed, which causes a problem such as expansion in the heating process. For this reason, it is difficult to make the FPC sufficiently thin.

Further, for the purpose of improving the light shielding property and the design property, a coverlay film in which a black pigment is contained in either or both of a polyimide film containing a black pigment or a dye, an electric insulating film and a thermosetting adhesive has been proposed Patent Document 1), the thinning is not considered at all.

Japanese Patent Application Laid-Open No. 9-135067

In view of the above background, it is an object of the present invention to provide a coverlay film having good processability and workability and excellent followability to an FPC despite being a thin film.

In order to improve handleability, in the present invention, a substrate made of a thin film of a dielectric resin and an adhesive layer are sequentially laminated on one surface of a support film. Further, after the adhesive layer is superimposed on the FPC and thermocompression-bonded, the support film can be peeled off and transferred to the FPC.

In addition, in order to endure a severe bending operation and improve followability to an FPC, a substrate made of a thin film of a dielectric resin having a high tensile elongation is used. In the present invention, a technical idea is to produce a laminate in which an adhesive layer is laminated on a substrate made of at least a thin film resin layer of a dielectric.

In the present invention, in consideration of flexibility, the thin film resin layer of a coated dielectric is used as a base made of a thin film of a dielectric resin, and the thickness of the entire coverlay film excluding the support film and the release film is reduced to 15 占 퐉 or less .

Further, in the present invention, an adhesive layer is formed between the base material and the thermosetting adhesive layer in order to increase the adhesion between the base made of a thin film resin layer such as polyimide and the thermosetting resin layer, and the adhesive layer to be fused to the FPC as a thermosetting resin layer You may.

Further, in order to solve the above-described problems, the present invention is characterized in that a base material and a thermosetting adhesive layer each formed of a thin film resin layer of a coated dielectric are sequentially laminated on one side of a support film, Wherein the film has a tensile elongation of 100% or more.

Further, in order to solve the above problems, the present invention is characterized in that a base material, a thin film adhesive layer, and a thermosetting adhesive layer are sequentially laminated on one surface of a support film, And a tensile elongation according to the method of -K-7127 is 100% or more.

It is preferable that a light absorbent is contained in at least one of the substrate, the thin film adhesive layer, and the thermosetting adhesive layer.

The substrate is made of an insulating layer formed using a solvent-soluble polyimide, and preferably has a thickness of 1 to 9 mu m.

Wherein the substrate 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, manganese oxide, .

Wherein the adhesive layer of the thin film is at least one kind of black pigment selected from the group consisting of non-conductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, manganese oxide, It is preferable to include a light absorbent.

It is preferable that the thermosetting adhesive layer is a flame-retardant thermosetting adhesive comprising a polyurethane resin containing flame retardant and an epoxy resin.

Wherein the thermosetting adhesive layer is made of one or more 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, manganese oxide, It is preferable to include a light absorbent.

Further, the present invention provides a cellular phone in which the coverlay film is used as an FPC protecting member.

Further, the present invention provides an electronic apparatus wherein the coverlay film is used as an FPC protecting member.

According to the coverlay film of the present invention, when a substrate made of a thin film resin having a high tensile elongation and an appropriate tensile strength is used, it is possible to perform a solder reflow step It is possible to manufacture a thin film coverlay film which does not cause problems due to swelling or penetration of the plating liquid in a process such as a plating process.

Further, by using a thin film resin film (thickness of 1 to 9 mu m) of a polyimide film having insulating properties as a substrate, it is possible to have an excellent bending property capable of withstanding a severe bending operation. As a result, the total thickness of the coverlay film excluding the support film and the release film can be suppressed to 15 μm or less, contributing to the reduction of the total thickness of the cellular phone and the electronic device.

By mixing one or more black pigments or a light absorbent composed of a colored pigment in the base material or adhesive layer, it is possible to perform specific coloring on one side of the coverlay film.

As described above, according to the present invention, in a heating process such as a solder reflow process after covering a wiring board or the like, it is thin and rich in flexibility that does not cause problems due to expansion or penetration of the plating liquid, It is possible to provide a coverlay film having excellent bending properties that does not deteriorate the FPC protection performance even if it is used.

1 is a schematic sectional view showing a first embodiment of a coverlay film according to the present invention.
2 is a schematic cross-sectional view showing a second embodiment of a coverlay film according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described. The present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. The present embodiment includes the following first and second embodiments.

When the coverlay film of the present embodiment is applied to an FPC or the like as an adherend, the outer surface of the coverlay film is a dielectric, and the wiring and circuit components of the FPC can be electrically insulated. In addition, the coverlay film of the present embodiment has a reduced thickness as a whole in order to improve the bending property with respect to the bending operation.

In the coverlay film 10 of the first embodiment shown in Fig. 1, the base material 12 is flexible, has a thickness of 1 to 9 mu m, a tensile elongation of 100% or more, for example, And a polyimide film formed using a polyimide resin. A support film 11 is laminated on one surface of the base material 12 and an adhesive layer 13 is laminated on the other surface of the base material 12. [ The adhesive layer 13 is an electrically insulating adhesive layer that is adhered to the surface of the FPC and is, 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 a coverlay film 15 in which the support film 11 and the release film 19 are removed and an adhesive layer 13 is laminated on one side of the base 12 have. In the first embodiment, the adhesive layer 13 may be in contact with one surface of the base material 12. [

In the coverlay film 20 of the second embodiment shown in Fig. 2, the base material 12 is flexible, has a thickness of 1 to 9 mu m, a tensile elongation of 100% or more, for example, And a polyimide film formed using a polyimide resin. A support film 11 is laminated on one surface of the base material 12 and an adhesive layer 14 and an adhesive layer 13 are laminated on the other surface of the base material 12 in this order. The adhesive layer 14 is an adhesive layer of a thin film which improves the adhesion between the adhesive layer 13 and the substrate 12. The adhesive layer 13 is an electrically insulating adhesive layer that is adhered to the surface of the FPC and is, 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 20 is formed by removing the support film 11 and the release film 19 to form a coverlay film 16 having a structure in which adhesive layers 13 and 14 are laminated on one surface of the base 12 Can be used. In the second embodiment, the adhesive layer 13 is in contact with the adhesive layer 14, and the adhesive layer 14 is in contact with one surface of the base material 12. [

(materials)

The base material 12 of the coverlay films 10, 15, 16, and 20 according to the present embodiment is an insulating layer comprising a thin film resin layer of a dielectric. Since the thin film resin film of the polyimide film formed by using the solvent-soluble polyimide has high mechanical strength, heat resistance, insulation, and solvent resistance characteristic of the polyimide resin and is believed to be chemically stable up to about 260 캜, .

As the polyimide, thermosetting polyimide resulting from dehydration condensation reaction by heating of polyamic acid and solvent soluble polyimide soluble in a solvent which is a condensation condensation type are available.

A commonly known method for producing a general polyimide film is to synthesize an imide precursor polyamic acid by reacting a diamine and a carboxylic acid dianhydride in a polar solvent and then heating the polyamic acid by heat or using a catalyst to dehydrate and cyclize To form the corresponding polyimide. However, in the imidation step, the temperature of the heat treatment is preferably in the range of 200 to 300 占 폚. If the heating temperature is lower than this temperature, the imidization may not progress, which is not preferable. If the heating temperature is higher than the above-mentioned temperature, the compound may be decomposed thermally, which is considered to be undesirable.

The coverlay films 10, 15, 16, and 20 of this embodiment are intended to use an extremely thin polyimide film having a thickness of less than 10 mu m, in order to further improve the flexibility of the base material 12. [

In the present embodiment, a substrate formed by laminating a thin polyimide film on one side of a support film 11 used as a reinforcing material for strength, or a substrate formed of only a thin polyimide film without using the support film 11 may be used .

When the thickness of the polyimide film to be used is thinner than about 7 占 퐉, it is preferable to laminate a thin polyimide film on one surface of the support film 11 used as a reinforcing material for strength. For example, a coating solution containing polyamic acid may be cast on one side of the support film 11 and heated to form polyimide.

However, the polyimide film itself has heat resistance against heat treatment at a heating temperature of 200 to 250 占 폚. However, as a support film 11, a general heat-resistant resin film such as polyethylene When a film having a low heat resistance such as a terephthalate (PET) resin film is used, a method of forming a polyimide from a conventional imide precursor, polyamic acid, can not be employed.

Solvent-soluble polyimide can be formed by evaporating the solvent at a low temperature of less than 200 占 폚 after applying the coating liquid dissolved in a solvent since imidization of the polyimide is completed and soluble in a solvent. For this reason, the substrate 12 used in the coverlay film of the present embodiment is formed by applying a coating solution of a solvent-soluble polyimide condensed with water to a surface of one side of the support film 11, It is preferable to form the thin film resin film of the polyimide film formed by using the solvent-soluble polyimide. By doing so, an extremely thin polyimide film having a thickness of 1 to 9 m can be laminated on one side of the support film 11 made of a general heat-resistant resin film. The substrate 12 is formed by coating (coating) in the same manner as the adhesive layers 13 and 14 so that the substrate 12 and the adhesive layer 13 , And 14) can be continuously formed. Therefore, production in roll-to-roll is possible, and workability and productivity are excellent.

The solvent-soluble polyimide that can be used in the base material 12 of the present embodiment is not particularly limited, but a commercially available solvent-soluble polyimide coating liquid can be used. Specific examples of commercially available solvent-soluble polyimide coating liquids include Sorpi 6,6-PI (Sorpe Industries), Q-IP-0895D (PI Industrial Technology Research Institute), PIQ (Hitachi Chemical Industrial), SPI-200N Shin-Tetsu Chemical Co., Ltd.), Rika Coat SN-20, and Rika Coat PN-20 (Shin-Etsu Chemical Co., Ltd.). The method of applying the coating solution of the solvent-soluble polyimide on the support film 11 is not particularly limited and it is possible to coat it with a coater such as a die coater, a knife coater or a lip coater.

It is preferable that the thickness of the substrate 12 of the present embodiment (for example, the thickness of the polyimide film) is 1 to 9 占 퐉. When the thickness of the polyimide film is less than 0.8 탆, it is technically difficult to form the film because the mechanical strength of the film is low. In addition, when the thickness of the base material 12 such as a polyimide film is more than 10 mu m, it becomes difficult to obtain the coverlay films 15 and 16 which are thin and have excellent bending performance.

When the thickness of the polyimide film to be used is thinner than about 7 mu m, it is difficult to adjust the tension when the film is wound on the roll. Therefore, a thin polyimide film is laminated on one side of the support film 11, Or the like.

When the substrate 12 made of only a thin polyimide film is used without using the support film 11, the thickness is preferably about 1 to 9 占 퐉.

Further, the base material 12 of the present embodiment preferably has a high tensile elongation in order to improve followability to an FPC. The tensile elongation of the base material 12 is preferably 100% or more, more preferably 250% or less. It is preferable that the elastic modulus of the base material 12 is 1.0 GPa or more and 2.5 GPa or less. When the substrate 12 having a high tensile elongation is made of a polyimide film, it is preferable to use a polyimide material having, for example, three or more aliphatic units between the aromatic units. Further, it is preferable that the aliphatic unit includes a polyalkyleneoxy group having an alkylene group having about 1 to 10 carbon atoms.

The tensile elongation of the substrate is measured as the tensile strain of the plastic based on the description in JIS-K-7127. The elastic modulus of the base material is measured as the tensile elastic modulus of the plastic based on the description of JIS-K-7161.

The water vapor permeability of the polyimide film used as the base material 12 of the present embodiment is preferably 500 g / m < 2 > day or more. When the water vapor transmission rate is lower than 500 g / m 2 · day, the outflow gas from the remaining solvent or adhesive in the respective layers and the moisture in the film are rapidly heated in the heating process such as the solder reflow after covering the FPC There is a possibility that each layer is peeled off by steam. There is no particular upper limit on the water vapor permeability, but as long as the same material is used, the water vapor permeability is inversely proportional to the thickness, so that it is preferable that the water vapor permeability is included in the above-mentioned thickness range when the water vapor permeability is increased by reducing the thickness.

(Support film)

Examples of the substrate of the support film 11 used in the present embodiment include a polyester film such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, and a polyolefin film such as polypropylene and polyethylene have.

In the case where the substrate of the support film 11 has some degree of peeling property, for example, polyethylene terephthalate or the like, the support film 11 is not peeled off, The base material 12 made of a resin film may be laminated or the surface of the support film 11 may be peeled to make the base material 12 more easily peeled off.

When the base film used as the support film 11 does not have peelability, peeling treatment is carried out by applying a releasing agent such as aminoalkyd resin or silicone resin, followed by heating and drying. Since the coverlay films 10, 15, 16, and 20 of this embodiment are bonded to the FPC, it is preferable that silicone resin is not used for the peeling agent. When a silicone resin is used as a releasing agent, a part of the silicone resin is transferred to the surface of the base material 12 that is in contact with the surface of the support film 11 and the inside of the coverlay films 10, 15, 16, There is a risk of further shifting from the base material 12 to the surface of the adhesive layer 13. This is because the silicone resin transferred to the surface of the adhesive layer 13 may weaken the adhesive strength of the adhesive layer 13.

The thickness of the support film 11 used in the present embodiment is not particularly limited as it is excluded from the entire thickness of the coverlay films 15 and 16 when the cover film is used to cover the FPC, but is usually about 12 to 150 mu m. By using the support film 11, it is possible to improve the workability in forming the base material 12 and the adhesive layers 13 and 14, and the workability in the co-extrusion with the FPC.

The color of the support film 11 may be colorless (uncolored) or colored. When coloring the support film 11, it is preferable that the color is high in contrast to the colors of the coverlay films 15 and 16 except for the support film 11 and the release film 19. [ For example, when the coverlay films 15 and 16 are dark color such as black, the support film 11 is preferably a bright color such as white, yellow, and the like. This makes it possible to improve the handling properties such as peeling the coverlay films 15 and 16 from the support film 11 and the confirmation of whether or not the support film 11 is peeled off. The support film 11 may be colored by using a known pigment, dye or the like. As the support film 11, for example, a white PET film having a thickness of 30 占 퐉 or more and 60 占 퐉 or less can be cited.

(Thermosetting adhesive layer)

The coverlay films 10, 15, 16, and 20 according to the present embodiment are preferably an adhesive layer 13 to be bonded to an FPC, and a thermosetting adhesive layer is preferable. Examples of the thermosetting adhesive used in the adhesive layer 13 include thermosetting adhesives generally used such as acrylic adhesives, polyurethane adhesives, epoxy adhesives, rubber adhesives, and silicone adhesives. Further, flame retardants such as phosphorus and bromine-based flame retardants and the like are preferably mixed so as to have flame retardancy, but they are not particularly limited. A polyurethane resin containing phosphorus in the molecular structure of the resin may be used as a thermosetting adhesive by using a polyol compound as a raw material for the polyurethane or a phosphorus containing compound as the polyisocyanate compound. It is preferable that the thermosetting adhesive layer 13 contains a phosphorus-containing polyurethane resin composition and an epoxy resin.

The thickness of the thermosetting adhesive layer 13 is preferably 1 to 8 mu m, for example. The thermosetting adhesive layer 13 can be formed, for example, by coating. 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, have.

Although the adhesive force of the thermosetting adhesive is not particularly limited, the measuring method is a method A (in 90 ° direction peeling) of 8.1.1 of JIS-C-6471 " Test method for copper clad laminate for flexible printed circuit boards " / Inch < / RTI > is preferred. If the adhesive force is less than 5 N / inch, for example, the coverlay films 15 and 16 bonded to the FPC may peel or float due to heat or bending.

It is preferable that the thermosetting adhesive is not a pressure-sensitive adhesive exhibiting a pressure-sensitive adhesive property at room temperature, but an adhesive by heating and pressing, since the adhesive force hardly deteriorates against repeated bending. The conditions of the heat press bonding to the FPC are not particularly limited, but it is preferable that the heat press is performed for 60 minutes at a temperature of 160 캜 and a pressing force of 4.5 MPa, for example. The support film 11 may be removed from the coverlay films 15 and 16 when the coverlay films 15 and 16 except for the support film 11 and the release film 19 are heated and pressed against the FPC, It is also possible to heat-press the substrate 11 including the support film 11.

(Adhesive layer)

The adhesive layer 14 used for the coverlay films 16 and 20 of the second embodiment is formed in order to improve the adhesion between the thin film such as the polyimide film as the substrate 12 and the adhesive layer 13 as the thermosetting adhesive layer , And an anchor layer. As shown in the first embodiment, the adhesive layer 14 can be omitted.

It is preferable to use an adhesive excellent in heat resistance because the adhesive layer 14 has a bonding temperature of 150 to 250 캜 by heating and pressing the thermosetting adhesive layer 13 laminated thereon. Further, it is preferable that the adhesive resin has excellent adhesion to an insulating resin such as a polyimide film serving as the substrate 12 and the thermosetting adhesive layer 13.

As the adhesive resin composition used for the adhesive layer 14, a thermoplastic resin such as a polyester resin, a polyurethane resin, a (meth) acrylic resin, a polyethylene resin, a polystyrene resin, and a polyamide resin is preferably used. Further, it may be thermosetting type such as epoxy resin, amino resin, polyimide resin and (meth) acrylic resin.

Particularly preferable as the adhesive resin composition of the adhesive layer 14 is an adhesive resin composition for crosslinking a polyester resin composition having an epoxy group or an adhesive resin composition obtained by mixing an epoxy resin as a curing agent with a polyurethane resin. Therefore, the adhesive layer 14 has a harder property than the substrate 12 made of a thin film such as a polyimide film. The polyester-based resin composition having an epoxy group is not particularly limited, and for example, an epoxy resin (its uncured resin) having two or more epoxy groups per molecule and a polyvalent carboxylic acid having two or more carboxyl groups per molecule Reaction or the like. The crosslinking of the polyester resin composition having an epoxy group can be carried out by using a crosslinking agent for an epoxy resin reactive with an epoxy group.

The thickness of the adhesive layer 14 is preferably about 0.05 to 1 占 퐉. If the thickness of the adhesive layer 14 is about 0.05 to 1 占 퐉, sufficient adhesion with the thermosetting adhesive layer 13 can be obtained. When the thickness of the adhesive layer 14 is 0.05 탆 or less, adhesion between the base material 12 and the thermosetting adhesive layer 13 may be deteriorated. Even if the thickness of the adhesive layer 14 exceeds 1 占 퐉, it is not effective to increase the adhesive force to the base material 12 made of a polyimide film or the like and the thermosetting adhesive layer 13, The thickness exceeding 1 탆 is not preferable because the cost is increased. The adhesive layer 14 can be formed, for example, by coating.

(Light absorber)

The coverlay films 15 and 16 except for the support film 11 and the release film 19 are provided in order to impart shielding property to the coverlay films 15 and 16 in a state of being stuck to the FPC or to improve designability. The light absorbing agent may be contained in any layer constituting the light absorbing layer. The layer that can contain the light absorbent for this purpose is any layer that can be formed between the substrate 12, the thermosetting adhesive layer 13, or the substrate 12 and the thermosetting adhesive layer 13, , The substrate 12, the thermosetting adhesive layer 13, and the adhesive layer 14 can be mentioned. Examples of the light absorbing agent include at least one black pigment or color 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. It is preferable that the kind and the compounding amount of the light absorbent are selected so that the layer containing the light absorbing agent can maintain electrical insulation.

In the first embodiment shown in Fig. 1, a light absorber can be added to either or both of the base material 12 and the thermosetting adhesive layer 13. Fig. A light absorbent may be added only to the base material 12 or a light absorbent may be added only to the thermosetting adhesive layer 13 and a light absorbent may be added to the base material 12 and the thermosetting adhesive layer 13.

In the second embodiment shown in Fig. 2, a light absorbent may be added to at least one layer of the base material 12, the adhesive layer 14, and the thermosetting adhesive layer 13. For example, a light absorbent may be added to the thermosetting adhesive layer 13 and the adhesive layer 14, or a light absorbent may be added to the substrate 12 and the adhesive layer 14, A light absorber may be added to all the layers of the base material 12, the adhesive layer 14 and the thermosetting adhesive layer 13 or a light absorbent may be added only to the base material 12 and the thermosetting adhesive layer 13 ) May be added to the substrate 12 and the light absorbing agent may be added to the thermosetting adhesive layer 13.

The light transmittance of the coverlay films 15 and 16 excluding the support film 11 and the release film 19 is preferably 5% or less. The light transmittance includes visible light transmittance, total light transmittance, and the like. In the case where the substrate 12 is composed of a solvent-soluble polyimide, the substrate 12 containing a light absorbing agent can be formed.

Among the light absorbers, black pigments such as carbon black are preferable for effectively lowering the light transmittance and improving the light shielding property. It is preferable that the light absorbent composed of a black pigment or a colored pigment is contained in a certain layer in an amount of 0.1 to 30% by weight. The black pigment or the colored pigment preferably has an average primary particle size of about 0.02 to 0.1 mu m by SEM observation. The thickness of the layer containing the light absorber is preferably larger than the particle diameter of the light absorber so that the fine particles of the light absorber are not exposed.

As the black pigment, silica particles or the like may be immersed in a black colorant so that only the surface layer is black, or may be formed of a black colored resin or the like to be black as a whole. The black pigment may be particles other than true black and includes particles having a color close to black such as gray, black brown, or black green, and may be used as long as it is a dark color that hardly reflects light.

(Peeling film)

As described above, the coverlay films 10 and 20 may have a release film 19 to protect the thermosetting adhesive layer 13. Examples of the base material of the release film 19 include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. A release agent such as an amino alkyd resin or a silicone resin is applied to these substrate films, followed by heating and drying. Since the coverlay films 10, 15, 16, and 20 of the present embodiment are bonded to the FPC in a state in which the peeling film 19 is removed, it is preferable that silicone resin is not used for the peeling agent. If a silicone resin is used as a releasing agent, a part of the silicone resin may be transferred to the surface of the thermosetting adhesive layer 13 that is in contact with the surface of the peeling film 19, which may weaken the adhesive force of the thermosetting adhesive layer 13 Because. The thickness of the release film 19 used in the present embodiment is not particularly limited as it is excluded from the total thickness of the coverlay films 15 and 16 used when the film is covered with the FPC, but is usually about 12 to 150 mu m.

(Coverlay film)

The coverlay films 10, 15, 16, and 20 of the present embodiment can be preferably used as a coverlay film having excellent bending properties, which can be used by being attached to an FPC subjected to repetitive bending operations. Further, the coverlay film of the present embodiment can be used for various electronic devices such as cellular phones, notebook computers, portable terminals, and the like as members for FPC protection. The cover layer films 10, 15, 16 and 20 of the present embodiment are manufactured by forming the base material 12 and the adhesive layers 13 and 14 on the support film 11 from the side close to the support film 11 And a method of sequentially laminating the material by applying the material.

The thickness of the entire coverlay films 15 and 16 excluding the support film 11 and the release film 19 is preferably 15 占 퐉 or less and may be, for example, 5 to 15 占 퐉 or 12 占 퐉 or less. The thicknesses of the coverlay films 15 and 16 are 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, 14) and the thickness of the thermosetting adhesive layer (13).

Example

Hereinafter, the present invention will be described in detail by way of examples.

(Example 1)

A polyethylene terephthalate (PET) film having a thickness of 50 탆 and subjected to a peeling treatment on one side thereof was used as the support film 11. On one surface of this support film 11, a coating solution of a solvent-soluble polyimide having a tensile elongation after drying of 170% was applied by pouring so as to have a thickness of 4 탆 after drying and dried to form a base material 12 ). Using a coating liquid for forming an adhesive layer 14 obtained by mixing a non-conductive carbon black as a black pigment of a light absorbent with a polyester resin composition having a heat-resistant temperature of 260 to 280 占 폚 on a formed substrate 12, So that the thickness of the adhesive layer 14 was 1 占 퐉. On the adhesive layer 14, 2.4 parts of a polyfunctional epoxy resin (Toyobo: HY-30) and 4.7 parts of fumed silica (manufactured by Nihon Aerosil Co., Ltd., R972) were added to 100 parts of a phosphorus-containing polyurethane resin solution (Toyobo Co., Were sequentially added and stirred to form a thermosetting adhesive agent having a thickness of 6 mu m after drying and dried to form a thermosetting adhesive layer 13 to obtain a coverlay film of Example 1. [

(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 the non-conductive carbon black to the coating solution for forming the adhesive layer 14, and the non-conductive carbon black is added to the coating solution of the solvent-soluble polyimide to form the substrate 12 A coverlay film of Example 3 was obtained in the same manner as in Example 1. [

(Example 4)

Non-conductive carbon black is added to the solvent-soluble polyimide coating solution having a tensile elongation after drying of 120% to form the base material 12 and the adhesive layer 14 is omitted to form a thermosetting adhesive layer ( 13) was formed in the same manner as in Example 1, to thereby obtain a coverlay film of Example 4.

(Comparative Example 1)

A polyimide film made of thermosetting polyimide (without Tg) having a thickness of 10 占 퐉 was used as the substrate 12 without using the support film 11 and a non-conductive carbon black was mixed with the thermosetting adhesive to form a thermosetting adhesive layer 13) was formed in the same manner as in Example 1, a coverlay film of Comparative Example 1 was obtained.

(Comparative Example 2)

A polyimide film made of a thermosetting polyimide (Tg-free) having a thickness of 12.5 占 퐉 was used as the substrate 12 without using the support film 11 and a non-conductive carbon black was mixed with the thermosetting adhesive to form a thermosetting adhesive layer 13) was formed in the same manner as in Example 1, and a coverlay film of Comparative Example 2 was obtained.

(Example 5)

Except that a base material 12 was formed using a coating solution of a solvent-soluble polyimide having an elastic modulus of 3.2 GPa and a thermosetting adhesive layer 13 was formed using a polyurethane resin not containing phosphorus, A coverlay film of Example 5 was obtained.

(Example 6)

Soluble polyimide coating solution having a tensile elongation after drying of 120% and a modulus of elasticity of 9.1 GPa was used to form the base material 12, and the non-conductive carbon black was not added to the coating solution for forming the adhesive layer 14 A coverlay film of Example 6 was obtained in the same manner as in Example 1 except that the adhesive layer 14 was formed.

(Evaluation method of followability)

The thermally cured adhesive surface of the coverlay film was superimposed on a test pattern in which a copper wiring pattern having a thickness of 75 mu m and L / S = 75 mu m / 75 mu m was formed on a polyimide film having a thickness of 12.5 mu m, min < / RTI > by thermal lamination. After the support film 11 was peeled off, it was hot-pressed under the conditions of 160 DEG C and 4.5 MPa for 65 minutes to obtain an evaluation sample of followability. The cross section of the obtained sample was observed. When it was followed in the wiring pattern, it was evaluated as "? &Quot;.

(Evaluation method of concealment property)

The obtained coverlay film was hot-pressed by the above-described method (refer to the followability evaluation method) in the test pattern (refer to the followability evaluation method) in which the above-described copper wiring pattern was formed to obtain a concealability evaluation sample. When no difference in concealability is observed between the polyimide portion and the copper wiring portion (particularly, the end portion) of the obtained sample, the portion where the copper wiring end portion is visible and the portion where the difference is observed is generated &Quot; DELTA ", and the majority of the copper wiring end portion was visible, and when the difference was observed, the result was " x ". In addition, evaluation was not conducted for Example 6 in which no light absorber was contained in any layer.

(Evaluation method of flame retardancy)

The obtained coverlay film was hot-pressed on a polyimide film having a thickness of 12.5 占 퐉 by the above-described method (see evaluation method of followability) to obtain a sample for evaluation of flame retardancy. The flame retardancy was evaluated according to the UL-94 thin-film material vertical combustion test (ASTM D4804) method, and when the flame retardancy corresponding to VTM-0 was evaluated as "O", when the flame retardancy was not evaluated as VTM-2 "

(Evaluation method of handling property)

When the obtained coverlay film was sampled at 50 cm in four directions and superimposed on the flexible printed wiring board, it was possible to quickly align the film, and the case where the handling was good was rated as " &Quot; x " was determined when the handling property was poor.

(Evaluation method of heat resistance)

The obtained coverlay film was hot-pressed on a polyimide film having a thickness of 25 占 퐉 by the above-described method (see evaluation method of followability) to obtain a sample for evaluation of heat resistance. The specimens were cut at a size of 2.5 cm x 3 cm, immersed in a soldering bath at 290 ° C for 10 seconds, and then pulled up. The appearance of the coverlay film after immersion in the solder bath was visually observed for any abnormality such as lifting, deformation or wrinkling. The case where the abnormality was not observed and the case where the abnormality was observed were evaluated as "? &Quot;

(Test result)

The coverlay film was evaluated by the above evaluation methods for Examples 1 to 6 and Comparative Examples 1 and 2, and the evaluation results obtained are shown in Tables 1 and 2. [ In the column of the material of the thermally adhesive adhesive layer, " PU1 " means a thermally adhesive adhesive containing flame retardant polyurethane used in Example 1, " PU2 " means a thermally adhesive adhesive containing polyurethane used in Example 5 Means a glue adhesive. What is written as " absent " in the column of thickness means that it has no layer.

According to the evaluation results shown in Tables 1 and 2, when the tensile elongation of the base material 12 is 100% or more, the followability and the heat resistance become good. That is, in the case where the tensile elongation of the base material 12 is low, the followability to the step is deteriorated and an abnormality occurs in the evaluation of the heat resistance.

According to Examples 1 to 4 and 6, the flame retardant can be secured even when the flame retardant is not blended in the base material 12 by adding the flame retardant to the thermosetting adhesive layer 13.

Further, according to Examples 1 to 6, the thickness of the support film was increased by the support film, and the handling property at the time of bonding to the flexible wiring board was improved. Since the support film 11 can be removed before or after hot pressing, And it is now possible to achieve both of the improvement and the thinning.

Furthermore, according to Examples 1 to 5, the light shielding property and the designability can be effectively improved by including a light absorbent in at least one of the base material, the thin film adhesive layer, and the thermosetting adhesive layer.

The coverlay film of the present invention can be used as a protective member of an FPC in various electronic apparatuses such as a cellular phone, a notebook computer, and a portable terminal.

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

Claims (9)

A substrate comprising a thin film resin layer of a coated dielectric and a thermosetting adhesive layer laminated on one surface of a support film in this order,
Wherein the substrate has a tensile elongation of 100% or more and 250% or less according to the method of JIS-K-7127, the thickness of the substrate is 1 to 9 占 퐉, the modulus of elasticity of the substrate is 1.0 GPa or more and 2.5 GPa or less,
The substrate is a polyimide film formed by using a polyimide having a polyalkyleneoxy group having an alkylene group of 1 to 10 carbon atoms and having at least three aliphatic units between the aromatic units,
Wherein the thickness of the thermosetting adhesive layer is more than 1 탆 and not more than 8 탆,
Wherein the thermosetting adhesive layer comprises a phosphorus-containing polyurethane resin composition and an epoxy resin. A substrate made of a thin film resin layer of a coated dielectric, an adhesive layer of a thin film, and a thermosetting adhesive layer are laminated on one surface of a support film in this order,
Wherein the substrate has a tensile elongation of 100% or more and 250% or less according to the method of JIS-K-7127, the thickness of the substrate is 1 to 9 占 퐉, the modulus of elasticity of the substrate is 1.0 GPa or more and 2.5 GPa or less,
The substrate is a polyimide film formed by using a polyimide having a polyalkyleneoxy group having an alkylene group of 1 to 10 carbon atoms and having at least three aliphatic units between the aromatic units,
Wherein the thickness of the adhesive layer of the thin film is 0.05 to 1 占 퐉, the thickness of the thermosetting adhesive layer is more than 1 占 퐉 and not more than 8 占 퐉,
Wherein the thermosetting adhesive layer comprises a phosphorus-containing polyurethane resin composition and an epoxy resin. 3. The method of claim 2,
Wherein a light absorbent is contained in at least one of the substrate, the thin film adhesive layer and the thermosetting adhesive layer. 3. The method according to claim 1 or 2,
Wherein the substrate 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, manganese oxide, And a cover layer film formed on the cover layer film. 3. The method of claim 2,
Wherein the adhesive layer of the thin film is at least one kind of black pigment selected from the group consisting of non-conductive carbon black, graphite, aniline black, cyanine black, titanium black, black iron oxide, chromium oxide, manganese oxide, Wherein the light absorbing agent comprises a light absorbing agent. 3. The method according to claim 1 or 2,
Wherein the thermosetting adhesive layer is a flame-retardant thermosetting adhesive comprising a polyurethane resin containing a flame retardant and an epoxy resin. 3. The method according to claim 1 or 2,
Wherein the thermosetting adhesive layer is made of one or more 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, manganese oxide, A coverlay film comprising a light absorbent. A cellular phone in which the coverlay film of claim 1 or 2 is used as an FPC protective member. An electronic device wherein the coverlay film of claim 1 or 2 is used as an FPC protective member.

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