KR20180037566A - Coverlay film - Google Patents

Abstract

The present invention provides a coverlay film having good processability and workability and excellent followability to an FPC even if the coverlay film is a thin film. A first insulating layer (12), a second insulating layer (13) and a thermosetting adhesive layer (14) are sequentially laminated on one surface of a support film (11), wherein the first insulating layer (12) contains a flame retardant and the first insulating layer (12), and a laminate (15) composed of the first insulating layer (12), the second insulating layer (13) and the thermosetting adhesive layer (14), from which the support film (11) is removed, has the tensile elongation of 100% or more.

Description

COVERLAY FILM

The present invention relates to a coverlay film. More particularly, the present invention relates to a thin film coverlay film having good processability and cohesion workability in a process for producing a substrate and excellent followability to unevenness and step difference of a flexible printed substrate (hereinafter referred to as FPC) .

2. Description of the Related Art In a portable electronic device such as a cellular phone, electronic components are integrated on a printed circuit board in order to make the size of the case small, thin, and portable. Further, in order to reduce the external dimensions of the case, the printed board is folded 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 smart phones and tablets) consume much more power than conventional cellular phones, and battery maintenance is getting worse. For this reason, it is necessary to increase the capacity and capacity of a battery as much as possible, and it is strongly required to reduce the size and thickness of members and components other than the battery. For example, thinning of the entire FPC by overlapping a coverlay film is required . Further, in recent years, light shielding properties and decorative properties have been emphasized, and coloring of coverlay films has been demanded.

Conventionally, as a coverlay film used for thinning the entire FPC, a thin polyimide film coated with an adhesive is used (Patent Document 1). However, the thin polyimide film has a problem in that the processability in the production process is poor and the workability is poor when it is attached to an FPC.

In addition, since the conventional coverlay film is difficult to reduce the thickness thereof, flexibility is not sufficient, so the followability to the step difference of the FPC is not sufficient, and a gap is formed, causing defects such as expansion in the heating step there was. For this reason, it is difficult to sufficiently thin the entire FPC to which the coverlay film is bonded.

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 which is excellent in processability and workability at the time of manufacturing an FPC even if it is a thin film, and has excellent followability to a step difference of an FPC.

In order to improve the workability in bonding the coverlay film to the FPC, in the coverlay film of the present invention, an insulating layer and a thermosetting adhesive layer are sequentially laminated on one surface of the support film. In addition, the coverlay film of the present invention is superimposed on the FPC with an adhesive layer interposed therebetween, thermally compressed, and then the cover film is peeled off, thereby transferring the coverlay film from the support film to the FPC.

Further, in order to endure the severe bending operation and to improve followability to the FPC, in the present invention, the tensile elongation of the laminate composed of the insulating layer and the adhesive layer is increased.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: forming a first insulating layer, a second insulating layer, and a thermosetting adhesive layer sequentially on one surface of a support film; Wherein a tensile elongation of the laminate composed of the first insulating layer, the second insulating layer, and the thermosetting adhesive layer from which the support film is removed is 100% or more.

It is preferable that the second insulating layer contains a flame retardant having a lower concentration than that of the first insulating layer or does not contain a flame retardant.

And the thickness of the first insulating layer is thinner than the thickness of the second insulating layer.

It is preferable that the thermosetting adhesive layer contains a polyurethane resin and an epoxy resin.

It is preferable that the polyurethane resin is a phosphorus-containing polyurethane resin.

It is preferable that at least one of the first insulating layer, the second insulating layer, and the thermosetting adhesive layer includes 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 wiring board or the like having a step difference is coated, it follows that there is no clearance, and in the subsequent processes such as a solder reflow process or a plating process, defects due to expansion or penetration of the plating liquid occur A thin film coverlay film can be produced.

Further, since the insulating layer or the adhesive layer contains a light absorbent, specific coloring can be performed on one side of the coverlay film.

In view of the above, according to the present invention, in the heating step such as the solder reflow step after covering the wiring board or the like, it is possible to reduce the occurrence of defects 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 when severe bending operations are repeatedly performed.

1 is a schematic sectional view showing an embodiment of a coverlay film of 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.

A first insulating layer 12, a second insulating layer 13 and a thermosetting adhesive layer 14 are sequentially laminated on one surface of a support film 11 as shown in Fig. The laminate 15 composed of the first insulating layer 12, the second insulating layer 13 and the thermosetting adhesive layer 14 can be integrally peeled from the support film 11 and can be bonded to an FPC or the like.

When the coverlay film 10 of the present embodiment is applied to an FPC or the like as an adherend, the outer surface of the coverlay film 10 serves as a dielectric, and the wiring and circuit components of the FPC can be electrically insulated. In addition, the coverlay film of the present embodiment can reduce the overall thickness to improve the bending property with respect to the bending operation.

(Support film)

As the substrate of the support film 11 used in the coverlay film 10 of the present embodiment, for example, a polyester film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc., a polypropylene or polyethylene And the like.

When the base material of the support film 11 has some degree of peeling property, for example, polyethylene terephthalate or the like itself, it is possible to directly laminate the support material film 11 on the support film 11 without performing the peeling treatment, Or the surface of the support film 11 may be subjected to a peeling treatment so as to facilitate peeling of the layered product 15 from the support film 11. [

When the base film used as the support film 11 does not have peelability, a release agent such as aminoalkyd resin or silicone resin is applied and then subjected to a peeling treatment by heating and drying. When the coverlay film 10 of the present embodiment is used for an FPC, it is preferable not to use a silicone resin for the peeling agent. A part of the silicone resin migrates to the surface of the insulating layers 12 and 13 in contact with the surface of the support film 11 and further passes through the inside of the layered product 15, There is a risk of shifting to the surface of the substrate 14. There is a possibility that the silicone resin transferred to the surface of the thermosetting adhesive layer 14 weakens the adhesive force of the thermosetting adhesive layer 14. [

The thickness of the support film 11 is not particularly limited because it is excluded from the total thickness of the layered product 15 when it is coated on the FPC, but it is usually about 12 to 150 mu m. By using the support film 11, it is possible to improve the workability in forming the insulating layers 12 and 13 and the thermosetting adhesive layer 14 and the workability at the time of applying the FPC to the FPC.

The color of the support film 11 may be colorless (uncolored) or colored. In the case of coloring the support film 11, it is preferable that the color is high in contrast to the color of the laminate 15 from which the support film 11 is removed. For example, when the laminate 15 is a dark color such as black, the support film 11 is preferably a bright color such as white or yellow. This makes it possible to improve the handling properties such as peeling the laminate 15 from the support film 11 and the checking ability 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 탆 or more and 60 탆 or less can be mentioned.

(Insulating layer)

The insulating layers 12 and 13 of the coverlay film 10 are insulating layers made of a thin dielectric resin layer or the like. 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 characteristic of the polyimide resin and is considered to be chemically stable up to about 260 캜, (12, 13).

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

A general method for producing a polyimide film is to synthesize a polyamic acid as an imide precursor by reacting a diamine and a carboxylic acid dianhydride in a polar solvent, and then converting the polyamic acid to a polyimide by dehydration cyclization. However, in the imidation step, 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, the imidization may not proceed, If the heating temperature is higher than the above-mentioned temperature, pyrolysis of the compound may occur, which is not preferable.

The coverlay film 10 of the present embodiment is intended to further improve the flexibility of the insulating layers 12 and 13 so that the extremely thin polyimide film having the total thickness of the insulating layers 12 and 13 of less than 10 占 퐉 Can be used. When the thickness of the polyimide film to be used is thinner than about 7 mu m, 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 a polyimide film.

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

Solvent-soluble polyimide can be formed by volatilizing the solvent at a low temperature of less than 200 캜 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 insulating layers 12 and 13 are formed by applying a coating solution of a solvent-soluble polyimide condensed with water to one surface of the support film 11 and then drying at a heating temperature of less than 200 DEG C to form a polyimide resin It is preferable to form a thin film of 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 insulating layers 12 and 13 are formed by applying (coating) in the same manner as the thermosetting adhesive layer 14 so that the insulating films 12 and 13 and the thermosetting Since the adhesive layer 14 and the like can be continuously formed, production in roll-to-roll is possible, and workability and productivity are excellent.

The solvent-soluble polyimide which can be used for the insulating layers 12, 13 of the present embodiment is not specifically limited, but it is possible to use a commercially available solvent-soluble polyimide coating liquid. Specific examples of commercially available solvent-soluble polyimide coating liquids include Sirupi 6,6-PI (Sirupi Industries), Q-IP-0895D (Piaget), PIQ (Hitachi Chemical), SPI-200N Tetsu Chemical), 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, a lip coater or the like.

The total thickness of the insulating layers 12 and 13 (for example, the thickness of the polyimide film) of the present embodiment is preferably 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. Further, when the thickness of the insulating layers 12 and 13 such as the polyimide film exceeds 10 mu m, it becomes difficult to obtain the laminate 15 having a thin and excellent bending performance. When the total thickness of the insulating layers 12 and 13 is thinner than about 7 占 퐉, it is preferable to use the supporting film 11 as a reinforcing material for the strength since it is difficult to adjust the tension when winding the film on the roll.

It is preferable that the insulating layers 12 and 13 of the present embodiment have a large tensile elongation so as to improve followability to the step difference of the FPC. The tensile elongation of one or both of the insulating layers 12 and 13 is preferably 100% or more, more preferably 250% or less. Here, the tensile elongation is the elongation at the point of time when the film is cut by the constant speed tensile in%, but the larger the tensile elongation is, the more flexible the film is against the tensile force. Therefore, in order for the laminate 15 to have sufficient flexibility and to exhibit excellent followability to the unevenness and step of the FPC, the tensile elongation is preferably 100% or more.

When the insulating layers 12 and 13 having a high tensile elongation are made of a polyimide film, it is preferable to use a polyimide material having, for example, three or more aliphatic units of carbon atoms 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 water vapor permeability of the polyimide film usable for the insulating layers 12 and 13 of the present embodiment is preferably 500 g / m 2 · day or more. When the water vapor transmission rate is lower than the above range, outgassing from residual solvent or adhesive in each layer or water vapor generated by suddenly heating the moisture in the film in the heating process such as solder reflow after covering the FPC, There is a possibility that the interlayer may peel off. The upper limit of the water vapor permeability is not particularly set. However, since the water vapor permeability is inversely proportional to the thickness when the same material is used, it is preferable that the water vapor permeability is within the above-mentioned range when the water vapor permeability is increased.

(Flame retardant)

In order to secure the flame retardancy of the layered product 15, the insulating layers 12 and 13 may contain a flame retardant. Examples of the flame retardant include inorganic flame retardants such as metal hydroxide, antimony and ruthenium, and organic flame retardants such as halogen (chlorine, bromine, etc.), phosphorus, and guanidine. Organic flame retardants such as phosphorus and bromine are preferable from the viewpoint of excellent dispersibility with an insulating resin such as polyimide. Examples of phosphorus-based flame retardants include aliphatic phosphate esters, aromatic phosphoric acid esters, aromatic condensed phosphoric acid esters, bisphenolphosphoric acid esters, halogen-containing phosphoric acid esters, halogen-containing condensed phosphoric acid esters and phosgene compounds.

When the flame retardant is an additive type flame retardant that does not react with the resin, the tensile elongation of the insulating layers 12 and 13 may decrease depending on the amount of the flame retardant added. The first insulating layer 12 which is the outermost layer contains the flame retardant and the second insulating layer 13 contains the flame retardant which is lower in concentration than the first insulating layer 12 It is preferable that the second insulating layer 13 contains a flame retardant or the second insulating layer 13 does not contain a flame retardant. It is also preferable that the thickness of the first insulating layer 12 is thinner than the thickness of the second insulating layer 13. [ The thickness of the first insulating layer 12 is, for example, 0.5 to 5 占 퐉. The thickness of the second insulating layer 13 is, for example, 2 to 9 占 퐉.

The ratio of the resin contained in the insulating layers 12 and 13 to the flame retardant can be appropriately set. In the first insulating layer 12, the flame retardant is preferably 20 to 200 parts by weight based on 100 parts by weight of the resin. In the second insulating layer 13, 0 to 100 parts by weight of the flame retardant is preferable to 100 parts by weight of the resin. Here, the ratio of the flame retardant to the resin of 100 parts by weight means that the flame retardant is not included in the amount of 0 parts by weight. The flame retardant may have a concentration distribution in the thickness direction of the insulating layer.

The interface between the first insulating layer 12 and the second insulating layer 13 may be an interface due to differences in the composition of the resin or additives, There is also.

The first insulating layer 12 may be a flame retardant layer in which an electrically insulating flame retardant is separated from the second insulating layer 13 by coating, coagulation, precipitation, or the like. In this case, the first insulating layer 12 may not include a resin, or may be made of resin or the like as a binder of the flame retardant.

(Thermosetting adhesive layer)

A thermosetting adhesive layer 14 is preferable as an adhesive layer used for bonding the layered product 15 of the coverlay film 10 to the FPC. The thermosetting adhesive used for the thermosetting adhesive layer 14 may be an electrically insulating adhesive layer. Specific examples of the thermosetting adhesive include thermosetting adhesives such as acrylic adhesives, polyurethane adhesives, epoxy adhesives, rubber adhesives, and silicone adhesives. . Further, thermosetting adhesives which have flame retardancy by mixing flame retardants such as phosphorus and bromine are preferably used, but are not particularly limited. A polyol compound as a raw material for polyurethane or a phosphorus containing compound as a polyisocyanate compound may be used and a polyurethane resin containing phosphorus in the molecular structure of the resin may be used as a thermosetting adhesive. It is preferable that the thermosetting adhesive layer 14 contains a polyurethane resin and an epoxy resin, and the polyurethane resin is more preferably a phosphorus-containing polyurethane resin.

The thickness of the thermosetting adhesive layer 14 is preferably, for example, 1 to 8 mu m. The thermosetting adhesive layer 14 can be formed, for example, by coating.

Although the adhesive strength of the thermosetting adhesive layer 14 is not particularly limited, the measuring method is preferably in the range of 5 to 30 N in the method A (90 DEG direction separation) of JIS-C-6471 " Test Method for Copper Laminates for Flexible Printed Circuit Boards & / Inch < / RTI > is preferred. When the adhesive force is less than 5 N / inch, for example, the laminate 15 bonded to the FPC sometimes peels off or peels due to heat or bending.

It is preferable that the thermosetting adhesive layer 14 is not a pressure-sensitive adhesive showing a pressure-sensitive adhesive property at room temperature but an adhesive layer showing adhesiveness by heating and pressing, since the adhesive force hardly deteriorates against repetitive bending. The conditions of the heating and pressure bonding to the FPC are not particularly limited. For example, conditions under which the temperature is 160 DEG C and the pressing force is 4.5 MPa and heat press is performed for 60 minutes can be exemplified.

When the laminate 15 is heated and pressed against the FPC, the support film 11 may be peeled off from the laminate 15 in advance. It is also possible to heat-press the FPC with the support film 11 being laminated on the layered product 15. In this case, the support film 11 may be peeled off from the laminate 15 after the heating and pressure bonding treatment to the FPC.

(Anchor layer)

The anisotropic adhesive layer 14 is formed between the second insulating layer 13 and the thermosetting adhesive layer 14 in order to improve the adhesion between the insulating layers 12 and 13 and the thermosetting adhesive layer 14 as the base of the layered product 15. [ A layer (not shown) may be formed. It is preferable to use an adhesive excellent in heat resistance because the anchor layer can withstand the adhesive temperature of the thermosetting adhesive layer 14 by heating and pressing even at 150 to 250 캜. An anchor layer excellent in adhesion to the insulating layers 12, 13 and the thermosetting adhesive layer 14 is preferable. On the other hand, when the adhesive force is sufficient, the anchor layer may be omitted and the second insulating layer 13 and the thermosetting adhesive layer 14 may be in direct contact with each other.

As the adhesive resin composition used for the anchor layer, a thermoplastic resin such as a polyester resin, a polyurethane resin, a (meth) acrylic resin, a polyethylene resin, a polystyrene resin or 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 anchor layer 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 anchor layer has harder physical properties than the insulating layers 12 and 13 made of a thin film such as a polyimide film. The polyester resin composition having an epoxy group is not particularly limited, and examples thereof include 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 And the like. The crosslinking of the epoxy 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 anchor layer is preferably about 0.05 to 1 占 퐉, and if it is a thickness of about 0.05 to 1 占 퐉, sufficient adhesion with the thermosetting adhesive layer 14 can be obtained. When the thickness of the anchor layer is 0.05 탆 or less, adhesion between the insulating layers 12 and 13 and the thermosetting adhesive layer 14 may be deteriorated. Further, even if the thickness of the anchor layer exceeds 1 탆, it is not effective in increasing the adhesion between the insulating layers 12, 13 and the thermosetting adhesive layer 14, and the thickness and cost of the layered product 15 are increased, I do not. The anchor layer can be formed, for example, by application.

(Light absorber)

The light absorbing agent may be contained in any layer constituting the laminate 15 in order to impart light shielding property to the laminate body 15 in the state of being bonded to the FPC or to improve designability. A layer capable of containing a light absorber may be formed between one or both of the insulating layers 12 and 13, the thermosetting adhesive layer 14 or between the insulating layers 12 and 13 and the thermosetting adhesive layer 14 For example, one or two or more layers of at least any one of insulating layers 12 and 13, for example, a thermosetting adhesive layer 14, and an anchor layer. The thermosetting adhesive layer 14 may contain a light absorber and the insulating layers 12 and 13 composed of a solvent-soluble polyimide may contain a light absorber. When the layer (light absorbing layer) containing the light absorbing agent also serves as at least one of the insulating layers 12 and 13 or the thermosetting adhesive layer 14, the light absorbing layer It is preferable since the increase in thickness can be suppressed.

Examples of the light absorbing agent include at least one black pigment or colored 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 type and the amount of the light absorbing agent are selected so that the light absorbing layer maintains electric insulation.

The light absorbent composed of a black pigment or a colored pigment is preferably contained in an amount of 0.1 to 30% by weight in any layer. The black pigment or colored pigment preferably has an average primary particle size of about 0.02 to 0.1 mu m by SEM observation. It is preferable that the thickness of the light absorbing layer is thicker than the particle diameter of the light absorbent so that the fine particles of the light absorbing agent are not exposed.

The light transmittance of the layered product 15 from which the support film 11 is removed is preferably 5% or less. The light transmittance includes visible light transmittance and total light transmittance.

Among the light absorbers, black pigments such as carbon black are preferable for effectively lowering the light transmittance and improving the light shielding property. 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 coloring resin or the like to be black throughout. In addition, the black pigment can be used as long as it contains particles exhibiting colors similar to black, such as gray, blackish brown, or darkish green, in addition to true black, and a dark color that hardly reflects light.

(Peeling film)

The coverlay film 10 can bond the release film 19 onto the thermosetting adhesive layer 14 to protect the thermosetting adhesive layer 14. 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. These base films are coated with a release agent such as aminoalkyd resin or silicone resin, and then subjected to peeling treatment by heating and drying. Since the coverlay film 10 of the present embodiment is bonded to the FPC in a state in which the peeling film 19 is removed, it is preferable not to use a silicone resin for the peeling agent. If the silicone resin is used as a releasing agent, there is a possibility that a part of the silicone resin migrates to the surface of the thermosetting adhesive layer 14 that is in contact with the surface of the peeling film 19, and weakens the adhesive force of the thermosetting adhesive layer 14 Because.

The thickness of the peeling film 19 is not particularly limited because it is excluded from the total thickness of the layered product 15 when it is coated on the FPC, but it is usually about 12 to 150 mu m.

(Coverlay film)

The coverlay film 10 of the present embodiment can be preferably used as a coverlay film excellent in bending properties, which can be used by being fused to an FPC subjected to repetitive bending operations. Further, the FPC in which the coverlay film of the present embodiment is combined can be used for various electronic devices such as cellular phones, notebook computers, portable terminals, and the like.

The insulating layer 12 and the thermosetting adhesive layer 14 are formed on the supporting film 11 in such a manner that the insulating films 12 and 13 and the thermosetting adhesive layer 14 are sequentially formed on the side close to the supporting film 11 And a method of laminating by coating. Further, as described above, the release film 19 may be bonded onto the thermosetting adhesive layer 14.

It is preferable that the coverlay film 10 of the present embodiment is used in the state of the layered body 15 when being bonded to the FPC when the FPC is bent. The laminate 15 is a laminate obtained by removing the support film 11 and the release film 19 from the coverlay film 10 when the coverlay film 10 has the release film 19, And the support film 11 is removed when the ray film 10 does not have the release film 19. The layered product 15 may include the above-described anchor layer, light absorbing layer, or the like.

The total thickness of the layered product 15 is preferably 15 占 퐉 or less, for example, 5 to 15 占 퐉 and 12 占 퐉 or less. The tensile elongation of the layered product 15 is preferably 100% or more, more preferably 150% or more, or 150% or less.

Example

Hereinafter, the present invention will be described in detail with reference to Examples.

(Example 1)

A polyethylene terephthalate (PET) film having a thickness of 50 탆 and subjected to a peeling treatment on one side was used as the support film 11.

On one side of the support film 11, a coating solution of a solvent-soluble polyimide resin containing 50 parts by weight of a phosphorus-based flame retardant per 100 parts by weight of the resin was applied by pouring and dried to a thickness of 1 mu m to form a first insulation layer 12).

A coating solution of a solvent-soluble polyimide resin containing no flame retardant and having a tensile elongation after drying of 170% on the first insulating layer 12 was applied by pouring and dried to a thickness of 3 탆 after drying to form a second insulating layer 13 ).

On the second insulating layer 13, 2.4 parts by weight of a polyfunctional epoxy resin (manufactured by Toyobo Co., Ltd., HY-30) and 100 parts by weight of a phosphorus-containing polyurethane resin solution (manufactured by Toyobo Co., R972) were added in this order and stirred to form a thermosetting adhesive layer. The thermosetting adhesive layer was applied and dried to a dry thickness of 8 μm to form a thermosetting adhesive layer 14 to obtain a coverlay film of Example 1.

(Examples 2 and 3)

The coverlay film of Examples 2 and 3 was produced in the same manner as in Example 1 except that the proportion of the phosphorus-containing flame retardant contained in the first insulating layer 12 was changed to 100 parts by weight in Example 2 and 150 parts by weight in Example 3, ≪ / RTI >

(Examples 4 to 6)

A coating solution for forming the second insulating layer 13 was prepared in the same manner as in Examples 1 to 3 except that a coating solution of a solvent-soluble polyimide resin containing 20 parts by weight of a phosphorus-containing flame retardant per 100 parts by weight of the resin The coverlay films of Examples 4 to 6 were obtained.

(Example 7)

A coverlay film of Example 7 was obtained in the same manner as in Example 2 except that the thickness of the first insulating layer 12 was 2 占 퐉 and the thickness of the second insulating layer 13 was 7 占 퐉.

(Comparative Example 1)

The coating liquid for forming the first insulating layer 12 is a coating liquid of a solvent-soluble polyimide resin not containing a flame retardant and the coating liquid for forming the second insulating layer 13 is a coating liquid A coverlay film of Comparative Example 1 was obtained in the same manner as in Example 1 except that a coating solution of a solvent-soluble polyimide resin containing 100 parts by weight of a phosphorus-based flame retardant was used.

(Comparative Example 2)

Soluble polyimide resin was used as the solvent-soluble polyimide resin used for forming the insulating layers 12 and 13, and a solvent-soluble polyimide resin having a lower tensile elongation after drying and coating was used, Ray film.

(Measurement method of tensile elongation)

According to IPC-TM-650 2.4.19, the sample size was measured with a width of 15 mm, a chuck distance of 100 mm, and a measurement speed of 50 mm / min (the sample number N = 5 was measured and the average value thereof was taken).

The tensile elongation of the laminate was measured by taking a laminate obtained by removing the support film as a sample.

The tensile elongation of the second insulating layer was measured by applying a coating liquid for forming a second insulating layer on one side of the same release film as the support film and peeling off the release film after drying to obtain a sample of the second insulation layer as a sample Respectively.

(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 a thickness of 75 mu m / 75 mu m was formed on a polyimide film having a thickness of 12.5 mu m, And laminated by thermal lamination at 1 m / min. 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 a followability evaluation sample.

The cross section of the obtained sample was observed to observe very well the wiring pattern. When the appearance was satisfactory, "? &Quot;, followed by the wiring pattern, but when the wiring edge was thinned, "Quot;, and " x " when the coating film of the wiring edge portion was cut off.

(Evaluation method of flame retardancy)

The obtained coverlay film was hot-pressed to 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 method of the UL-94 clap material vertical combustion test (ASTM D4804). When the flame was not raised, "?" Was used. When the flame was not flame- , &Quot; DELTA " indicating combustion up to a marking degree, and " x "

(Test result)

For the Examples 1 to 7 and Comparative Examples 1 and 2, the evaluation results obtained by evaluating the coverlay film by the above evaluation method are shown in Table 1.

In the first insulating layer and the second insulating layer, " parts by weight " means parts by weight of the flame retardant relative to 100 parts by weight of the resin. "PI1" means the solvent-soluble polyimide resin used in Example 1, and "PI2" means the solvent-soluble polyimide resin used in Comparative Example 2.

&Quot; PU1 " means a thermally adhesive adhesive containing a flame-retardant polyurethane used in Example 1, in the material of the thermally adhesive adhesive layer.

The thickness of the laminate means the total thickness of the coverlay film from which the support film is removed, and the " total thickness " means the thickness of the entire coverlay film including the support film.

On the other hand, of a phosphorus-based flame retardant is an aromatic condensed phosphoric acid ester _{[(CH 3) 2 C 6} H 3 O] 2 P (O) OC 6 H 4 OP (O) [OC 6 H 3 (CH 3) 2] using the _second Respectively.

According to the evaluation results shown in Table 1, it is found that when the tensile elongation of the laminate is 100% or more, the followability is improved. That is, when the tensile elongation of the laminate was low, the followability to the step difference deteriorated. When the tensile elongation of the second insulating layer was low, the tensile elongation of the laminate tended to decrease.

In Comparative Example 1 in which the flame retardant was added to the second insulation layer without adding the flame retardant to the first insulation layer, the total amount of the flame retardant contained in the first and second insulation layers was larger than that in Examples 1 to 7, The flame retardancy of the laminated body as a whole deteriorated because the flame retardancy of the first insulating layer as the outermost layer in the sample in which the support film was peeled was low.

10 ... Coverlay film, 11 ... Support film, 12 ... A first insulating layer, 13 ... A second insulating layer, 14 ... Thermosetting adhesive layer, 15 ... The laminate, 19 ... Peeling film.

Claims (8)

Wherein a first insulating layer, a second insulating layer, and a thermosetting adhesive layer are sequentially laminated on one surface of a support film, the first insulating layer contains a flame retardant,
Wherein a tensile elongation of the laminate composed of the first insulating layer, the second insulating layer, and the thermosetting adhesive layer from which the support film is removed is 100% or more. The method according to claim 1,
Wherein the second insulating layer contains a lower flame retardant than the first insulating layer or does not contain a flame retardant. 3. The method according to claim 1 or 2,
Wherein the thickness of the first insulating layer is thinner than the thickness of the second insulating layer. 4. The method according to any one of claims 1 to 3,
Wherein the thermosetting adhesive layer contains a polyurethane resin and an epoxy resin. 5. The method of claim 4,
Wherein the polyurethane resin is a phosphorus-containing polyurethane resin. 6. The method according to any one of claims 1 to 5,
Wherein at least one of the first insulating layer, the second insulating layer, and the thermosetting adhesive layer comprises a light absorbing agent. A cellular phone in which the coverlay film of any one of claims 1 to 6 is used as an FPC protective member. An electronic device wherein the coverlay film of any one of claims 1 to 6 is used as an FPC protecting member.

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