JP2009084507A - Multilayered adhesive film, coverlay film using it, and multilayered adhesive film with copper foil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered adhesive film having sufficient adhesive strength to two different materials, which are metal foil and a plastic film, and to provide a coverlay film and a multilayered adhesive film with copper foil. <P>SOLUTION: In the multilayered adhesive film 14, at least a first thermosetting adhesive layer 11 having adhesive strength 3N/10 mm or more (at 23°C) to a plastic film 13 and a second thermosetting adhesive layer 12 having adhesive strength 3N/10 mm or more (at 23°C) to a smooth surface of the metal foil are formed on the outer layer. The coverlay film 10 is produced by laminating the plastic film 13 onto the first thermosetting adhesive layer 11 side of the multilayered adhesive film. The multilayered adhesive film with copper foil 19 is produced by laminating copper foil onto the second thermosetting adhesive layer 12 side of the multilayered adhesive film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an adhesive film used for a circuit board, a coverlay film using the same, and a multilayer adhesive film with a copper foil.

  A flexible circuit board has a circuit wiring pattern formed on a copper-clad laminate with a copper foil provided on the surface of a flexible insulating base material. On this circuit wiring pattern, an electronic component such as a circuit component or an external substrate, or a circuit It is manufactured by forming a surface protective layer having an opening at a portion where a terminal for connection to the substrate is formed, punching it out with a mold or the like, and processing the outer shape. Moreover, a multilayer circuit board is manufactured by laminating each circuit board via an adhesive film.

  Here, the surface protective layer is a flexible insulating film having an adhesive layer on one side and is called a coverlay film. An opening is formed by punching this with a mold or the like, and this coverlay film is bonded onto the circuit wiring pattern to form a surface protective layer.

  In the production of a multilayer circuit board, an adhesive film and a coverlay film are attached to the multilayer circuit board using a method such as vacuum pressing. The adhesive film may be used to bond the metal foil, which is a circuit wiring pattern, and the plastic film, which is a flexible insulating base material, in which case the metal foil and the plastic film are bonded to two different materials. Sex is required.

  A coverlay film may be used for the inner layer of the multilayer circuit board. The coverlay film adheres onto the circuit wiring pattern to form a surface protective layer, and requires adhesion to a metal foil.

  With increasing solder melting point due to miniaturization of circuit wiring patterns and lead-free soldering, adhesive films and coverlay films are becoming increasingly demanding from manufacturers.

  In addition to adhesiveness, adhesive film and coverlay film have flowability, solder heat resistance, reflow heat resistance, migration resistance, solvent resistance, electrical properties as an insulating material, flowability to embed circuit wiring patterns, flame resistance There are many required characteristics such as sex.

  As one of the methods for reducing the flowability and improving the heat resistance, a method of blending an inorganic filler can be mentioned. Generally, when an inorganic filler is blended, the adhesiveness tends to decrease. It is difficult to improve an adhesive that has sufficient adhesion to two different types of materials such as plastic films and that satisfies all the required characteristics.

Adhesive films and coverlay films that satisfy the required properties other than adhesiveness, for example, adhere well to metal foil but do not adhere to plastic film, conversely adhere well to plastic film but adhere to metal foil There was a problem such as not.
JP 2005-154727 A JP 2005-235948 A

  Therefore, in view of the above problems, the object of the present invention is to satisfy the demands of the manufacturers of adhesive films and coverlay films that are becoming stricter year by year, and sufficient adhesion to two different types of materials, metal foil and plastic film. The present invention provides a multilayer adhesive film having a strength, a coverlay film, and a multilayer adhesive film with a copper foil.

  In order to achieve this purpose, we have eagerly studied the requirement of satisfying the demands of manufacturers of adhesive films and coverlay films, which are becoming stricter year by year, and having adhesion to two different materials, metal foil and plastic film. As a result, the adhesive has two or more adhesive layers, and is provided with an adhesive layer that sufficiently adheres to the metal foil on one adhesive layer, and sufficiently adheres to the plastic film on the other adhesive layer. It came to invent the adhesive film of the multilayer structure which provides a layer, a coverlay film, and the multilayer adhesive film with copper foil.

That is, the present invention provides [1] a first thermosetting adhesive layer having an adhesive strength to a plastic film of 3 N / 10 mm (23 ° C.) or higher, and an adhesive strength to a smooth surface of a metal foil of 3 N / 10 mm (23 And a second adhesive layer having at least a second thermosetting adhesive layer as an outer layer.
Moreover, this invention relates to the multilayer adhesive film as described in said [1] whose plastic film is a polyimide film.
Moreover, this invention relates to the multilayer adhesive film as described in said [1] or said [2] whose [3] metal foil is copper foil.
The present invention also provides [4] the above-mentioned [1] to [1], wherein the thermosetting adhesive layer contains (i) an elastomer or rubber, (ii) a thermosetting resin, (iii) a curing agent, and (iv) an inorganic filler. The multilayer adhesive film according to any one of [3] above.
The present invention also relates to [5] (i) the multilayer adhesive film according to the above [4], wherein the elastomer or rubber is acrylic rubber.
[6] The above [1] to [5], wherein the present invention has a higher melt viscosity at the time of heat-bonding the second thermosetting adhesive layer than [6] the first thermosetting adhesive layer. ] It is related with the multilayer adhesive film in any one of.
Moreover, this invention is [7] Said [6] that the difference of the melt viscosity at the time of heat adhesion of a 1st thermosetting adhesive layer and a 2nd thermosetting adhesive layer is 1000 Pa.s or more. The present invention relates to a multilayer adhesive film.
The present invention also provides [8] above [1] to [[] wherein a third thermosetting adhesive layer is provided between the first thermosetting adhesive layer and the second thermosetting adhesive layer. 7] The multilayer adhesive film according to any one of [7].
In addition, the present invention provides [9] any one of [1] to [8] above, wherein any one of the first thermosetting adhesive layer and the second thermosetting adhesive layer is colored. It relates to the multilayer adhesive film of description.
[10] The present invention also relates to a coverlay film in which a plastic film is laminated on the first thermosetting adhesive layer side of the multilayer adhesive film described in any one of [1] to [9].
The present invention also provides [11] a multilayer adhesive film with copper foil in which a copper foil is laminated on the second thermosetting adhesive layer side of the multilayer adhesive film according to any one of [1] to [9]. About.
The present invention comprises at least two or more adhesive layers, and each of the outermost layers is provided with an adhesive layer that sufficiently adheres to a metal foil and an adhesive layer that sufficiently adheres to a plastic film. A multilayer adhesive film characterized by the above.

  Further, in the present invention, at least two or more layers each having an adhesive layer that sufficiently adheres to the metal foil and an adhesive layer that sufficiently adheres to the plastic film are laminated on one side of the film base. The present invention relates to a coverlay film characterized by comprising an adhesive film layer comprising an adhesive layer on the film substrate side that sufficiently adheres to the plastic film in the adhesive film layer.

  According to the present invention, at least two of the outermost layers each have an adhesive layer that sufficiently adheres to the metal foil and an adhesive layer that sufficiently adheres to the plastic film as the adhesive layers of the adhesive film and the coverlay film. Adhesive film, coverlay film, multilayer with copper foil that can exhibit sufficient adhesion to two different types of materials, metal foil and plastic film, by providing an adhesive film layer that is laminated in layers An adhesive film can be provided.

The multilayer adhesive film for a circuit board of the present invention has at least two adhesive layers, and an adhesive layer that sufficiently adheres to a smooth surface of a metal foil and an adhesive that adheres sufficiently to a plastic film. It is characterized by comprising each agent layer in the outermost layer.
As a plastic film, it is preferable to exhibit a sufficient adhesive force with respect to a polyimide film having poor adhesiveness, because the adhesiveness is sufficient for other plastic films. In addition, copper foil is frequently used as the metal foil, and it is preferable to use an adhesive layer having sufficient adhesion to the copper foil because it can be applied in a wide range.

  Further, the cover lay film for a circuit board of the present invention has an adhesive layer that sufficiently adheres to the metal foil and an adhesive layer that sufficiently adheres to the plastic film on one side of the film base, respectively. The multilayer adhesive film layer of the present invention is provided by laminating at least two layers in the outer layer, and the adhesive layer that sufficiently adheres to the plastic film in the multilayer adhesive film layer is provided on the film substrate side. It is characterized by comprising.

  Furthermore, the multilayer adhesive film with copper foil for circuit boards of the present invention has an adhesive layer that adheres sufficiently to the metal foil and an adhesive layer that adheres sufficiently to the plastic film on one side of the copper foil. Each of the outermost layers is provided with the multilayer adhesive film layer of the present invention formed by laminating at least two layers, and an adhesive layer that sufficiently adheres to the metal foil in the multilayer adhesive film layer is a copper foil. It is characterized by being provided on the side.

  Here, the adhesive layer used for the multilayer adhesive film of the present invention, the coverlay film, and the multilayer adhesive film with copper foil for circuit boards is formed by laminating a plurality of adhesive layers each having different adhesive properties. Obtainable.

  Hereinafter, each embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view schematically showing the multilayer adhesive film of the present invention. FIG. 2 is a schematic cross-sectional view schematically showing the coverlay film of the present invention. FIG. 3 is a schematic cross-sectional view schematically showing the multilayer adhesive film with copper foil of the present invention.

  As shown in FIGS. 1, 2 and 3, in the configuration of the multilayer adhesive film (adhesive layer) 14 composed of a plurality of layers having different adhesive properties, the thickness of each adhesive layer 11, 12 is 25 μm or less, Preferably it is 10-25 micrometers. When the thicknesses of the adhesive layers 11 and 12 exceed 25 μm, it is difficult to control the flowability. On the other hand, the lower limit value of the thickness of each of the adhesive layers 11 and 12 is not particularly limited, but is preferably 10 μm or more because the main purpose is to obtain sufficient adhesive properties. .

  The thermosetting adhesive used for the adhesive layers 11 to 12 is not particularly limited. For example, (i) based on an elastomer or rubber, (ii) a thermosetting resin, and (iii) a curing agent. , (Iv) an inorganic filler, and (v) an adhesive containing other additives used as necessary.

  The solution of the adhesive composition used in the examples refers to a solution obtained by dissolving (or dispersing) each compounding component of the adhesive in (vi) an appropriate solvent.

(I) Elastomer or rubber (base component) The base component elastomer or rubber used in the thermosetting adhesive layer has flexibility and is generally acrylic rubber or nitrile rubber (hereinafter referred to as acrylonitrile butadiene). Rubber or NBR), styrene isoprene styrene block copolymer (hereinafter also referred to as SIS) and the like, and preferably acrylic rubber containing a carboxyl group as a functional group.

  The acrylic rubber containing a carboxyl group as a functional group is a vinyl monomer containing an acrylic acid alkyl ester (including a methacrylic acid ester, the same shall apply hereinafter) as a main component and a carboxylic acid as a functional group, and if necessary. A copolymer containing acrylonitrile, styrene and the like.

  Examples of the alkyl acrylate ester include ethyl acrylate (including ethyl methacrylate, the same applies hereinafter), propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, undecyl acrylate, Monomers such as lauryl acrylate, monomers having hydroxyl groups such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and allyl alcohol, and epoxy groups of epichlorohydrin modification products such as glycidyl acrylate and dimethylaminoethyl acrylate And the like. From these, one type or two or more types can be selected and used.

  Examples of the vinyl monomer containing the carboxylic acid as a functional group include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, and maleic anhydride. From these, one type or two or more types can be selected and used.

  The acrylic rubber polymerization method is not particularly limited, but a general suspension polymerization method can be used. For example, a dispersant such as polyvinyl alcohol (hereinafter also referred to as PVA), azobisisobutyronitrile, and the like. A mixture of two or more of the above acrylic monomers is dropped into a liquid in which a polymerization initiator such as (AIBN) or lauryl peroxide (LPO) is dispersed in an aqueous medium and polymerized. The polymer is washed with purified water to remove impurities, washed with water and dried by heating to remove residual monomers and moisture. The number average molecular weight of the polymer is preferably about 50,000 to 500,000, more preferably 40000 to 400,000. In addition to the suspension polymerization method, for example, conventionally known polymerization methods such as emulsion polymerization, solution polymerization, and bulk polymerization can be used.

  In addition, regarding the rubber having flexibility (other than acrylic rubber) which is a base component of the thermosetting adhesive, the polymerization method is not particularly limited, and a general suspension polymerization method, etc. Can be used. Further, the number average molecular weight of the obtained polymer (flexible rubber) is preferably about 50,000 to 500,000, more preferably 40000 to 400,000. In addition to the suspension polymerization method, conventionally known polymerization methods such as emulsion polymerization and bulk polymerization can be used.

  The compounding amount of the flexible elastomer or rubber which is the base component of the thermosetting adhesive is as follows: (ii) thermosetting resin, (iii) curing agent, and (iv) from the thermosetting adhesive. It is a residue obtained by subtracting the total amount of blending specified by the inorganic filler (further, other additive (v) blended as necessary). That is, the blending amount of the elastomer or rubber is in the range of 30 to 80 parts by weight, preferably 40 to 60 parts by weight with respect to 100 parts by weight of the total amount of the blending components of the adhesive. When the amount of the elastomer or rubber is less than 30 parts by weight, sufficient adhesion cannot be obtained, and when it exceeds 80 parts by weight, the heat resistance is lowered.

(Ii) Thermosetting resin The thermosetting resin used for the thermosetting adhesive is preferably an epoxy resin or a phenol resin. These may be used alone or in combination with an epoxy resin and a phenol resin.

  Here, the epoxy resin is a compound having two or more epoxy groups in the molecule, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac. Type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F novolak type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, bifunctional Diglycidyl etherified products of phenols, diglycidyl etherified products of bifunctional alcohols, hydrogenated products thereof, silane-modified epoxy resins, and the like can be used. These compounds can be used alone or in combination of two or more. The compounding amount of the epoxy resin is 10 to 100 parts by weight, preferably 30 to 80 parts by weight with respect to 100 parts by weight of the total amount of each component of the adhesive. If it is less than 10 parts by weight, sufficient heat resistance cannot be obtained, and if it exceeds 100 parts by weight, the peel adhesion strength is undesirably lowered.

  The silane-modified epoxy resin can be obtained by dealcoholizing an epoxy resin having an epoxy equivalent of 180 to 400 g / eq, an epoxy compound and an alkoxysilane partial condensate. The weight ratio of the epoxy resin and epoxy compound having an epoxy equivalent of 180 to 400 g / eq and the alkoxysilane partial condensate is particularly limited as long as the alkoxy group substantially remains in the silane-modified epoxy resin. However, the total equivalent of the hydroxyl group of the epoxy resin and the hydroxyl group of the epoxy compound having an epoxy equivalent of 180 to 400 g / eq / the equivalent of the alkoxy group of the alkoxysilane partial condensate (equivalent ratio) is 0.1 to 0.6. Is preferred. More preferably, it is 0.13-0.5. If the equivalent ratio is less than 0.1, unreacted alkoxysilane partial condensate increases, and if it exceeds 0.6, sufficient heat resistance cannot be obtained.

  The phenol resin may be of a resol type, and the molecular weight, softening point, hydroxyl equivalent, etc. of the phenol resin are not particularly limited. The resol-type phenol resin is obtained by adding excess formaldehyde to phenol and reacting with an alkali catalyst. When the resol-type phenol resin is heated or an acid is added, the reaction proceeds at room temperature and self-condenses. In addition to the self-condensation of phenol resin in the present invention, it is also reactive with flexible rubber (base component of thermosetting adhesive) such as acrylic rubber containing a carboxyl group as a functional group. Since it has, reflow solder heat resistance and volume resistance are improved. The blending amount of the phenol resin is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, with respect to 100 parts by weight of the total amount of the blending components of the adhesive. If the amount is less than 5 parts by weight, the crosslink density is lowered and sufficient reflow soldering heat resistance cannot be obtained. If the amount exceeds 50 parts by weight, the storage stability in the B-stage state is impaired, and the peel adhesion strength is reduced. Cause problems.

  When the epoxy resin and the phenol resin are used in combination as the thermosetting resin, the mixing ratio is not particularly limited, but epoxy resin: phenol resin (mass ratio) = 30 to 300: 100, preferably It is in the range of 50 to 250: 100. If the epoxy resin is less than 30 parts by weight relative to 100 parts by weight of the phenol resin, sufficient heat resistance cannot be obtained. When the amount exceeds 300 parts by weight, the peel strength decreases, which is not preferable.

(Iii) Curing Agent The curing agent used for the thermosetting adhesive is a curing agent or curing catalyst for a thermosetting resin such as an epoxy resin. For example, aromatic polyamines, boron trifluoride amine complexes such as boron trifluoride triethylamine complex, imidazole derivatives such as 2-alkyl-4-methylimidazole and 2-phenyl-4-alkylimidazole, phthalic anhydride, Known acids such as organic acids such as merit acid, dicyandiamide, triphenylphosphine, diazabicycloundecene and hydrazine can be used. In addition, these hardening | curing agents and hardening catalysts may be used independently, and may use 2 or more types together as needed. In order to improve the storage stability at the B stage, it is preferable that the curing agent and the curing catalyst hardly react at room temperature.

  The compounding amount (addition amount) of these curing agents or curing catalysts is 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of a thermosetting resin such as an epoxy resin. If it is less than 0.01 parts by weight, sufficient curing of a thermosetting resin such as an epoxy resin cannot be obtained, solder heat resistance and the like are reduced, and if it exceeds 10 parts by weight, the peel adhesion strength is reduced, Problems such as reduced storage stability occur.

(Iv) About Inorganic Filler The inorganic filler used in the thermosetting adhesive can be used as long as it is essentially electrically insulating, such as aluminum hydroxide and magnesium hydroxide. And metal oxides such as aluminum oxide and calcium oxide, silica, mica, talc, clay and the like. These can be used alone or in combination of two or more as required.

  The blending amount of the inorganic filler is 10 to 100 parts by weight, preferably 20 to 80 parts by weight, based on 100 parts by weight of the total active ingredients of elastomer or rubber + thermosetting resin. If it is less than 10 parts by weight, sufficient flame resistance cannot be obtained, and if it exceeds 100 parts by weight, problems such as a decrease in peel adhesion strength occur.

  The inorganic filler is adjusted to a particle size of 10 μm or less using a ball mill or the like (the particle size here refers to the maximum particle size). When the particle size of the inorganic filler is larger than 10 μm, when it is used as an adhesive film or a coverlay film, irregularities are generated on the film surface, and the peel adhesion strength, the solder heat resistance is lowered, and the appearance is impaired.

(V) Other Additives that may be Used as Needed In the above-described thermosetting adhesive, further, other additives that may be used as needed are within a range that does not impair the effects of the present invention. You may mix | blend inside. Specifically, for example, various silane coupling agents and the like can be appropriately mixed and used.

(Vi) About a suitable solvent Moreover, although it does not restrict | limit especially as a suitable solvent used in order to melt | dissolve (or disperse | distribute) each compounding component of the said adhesive agent, methyl ethyl ketone, toluene, DMF (N, N′-dimethylformamide), ethyl acetate, methanol, isopropyl alcohol, ethylene glycol and the like can be suitably used. In addition, the solvent may not be particularly used when it is in a solution form that can be suitably applied with only each component of the adhesive. In this case, the solvent is handled as a solution of adhesive = adhesive composition. be able to.

  As a compounding quantity of this solvent, it is 100-1000 weight part with respect to 100 weight part of total amounts of each compounding component of the said adhesive agent, Preferably it is the range of 200-600 weight part. When the amount of the solvent is less than 100 parts by weight, the viscosity of the adhesive solution is too high to be applied, and when it exceeds 1000 parts by weight, an adhesive layer having a desired thickness cannot be obtained.

In the multilayer adhesive film of the present invention, the first thermosetting adhesive layer and the second thermosetting adhesive layer are formed by forming a solvent solution or a dispersion solution of the thermosetting adhesive layer on the separator and forming a film by removing the solvent. Each of these thermosetting adhesive layers is formed and bonded together, or one of the thermosetting adhesive layers is formed on the separator, and another thermosetting adhesive layer is formed thereon. Also good.
The separator is preferably subjected to a release treatment, and the release-based paper-based separator is not particularly limited. For example, paper such as fine paper, kraft paper, roll paper, glassine paper, etc. A coating layer of a sealant such as clay, polyethylene, or polypropylene is provided on both sides, and a silicone-based, fluorine-based, or alkyd-based release agent is coated on each coated layer, and polyethylene, polypropylene , Various olefin films such as ethylene-α-olefin copolymer, propylene-α-olefin copolymer alone, and those obtained by applying the release agent on a film such as polyethylene terephthalate, etc. Because of the mold release force of silicone and the adverse effect of silicone on electrical properties, polypropylene sealing treatment is applied to both sides of high-quality paper. What used the alkyd type mold release agent on is preferable.

  The thickness of the release-treated separator is not particularly limited, but is in the range of 50 to 150 μm, preferably 80 to 120 μm. When the thickness of the release-treated separator is less than 50 μm, the strength as the separator is insufficient, and when it exceeds 150 μm, the curling may be increased when winding with a roll.

  Although it does not restrict | limit especially as the said PET film base separator by which the mold release process was carried out, What used the alkyd type mold release agent on the polyester film is mentioned. Preferred polyesters used in the polyester film include polyethylene terephthalate, a copolymer of ethylene terephthalate and ethylene isophthalate, polybutylene terephthalate and its copolymer, polybutylene naphthalate and its copolymer, polyhexamethylene naphthalate and Mention may be made of the copolymers. These polyester films have the advantages that they generate less dust and generate less gas during heating.

  The thickness of the release-treated PET film-based separator is not particularly limited, but is in the range of 25 to 100 μm, preferably 38 to 75 μm. When the release-treated PET film-based separator has a thickness of less than 25 μm, it is difficult to peel off when the separator is peeled off, and the workability is reduced, and when it exceeds 100 μm, curling occurs when winding with a roll. May grow.

  Although it does not restrict | limit especially as a plastic film (coverlay structure plastic film) 13 used with the said coverlay film, For example, a polyimide film, PET film, a polyethylene naphthalate film etc. are mentioned.

  The thickness of the plastic film 13 is not particularly limited, but is 4 to 50 μm, preferably 12 to 25 μm. When the thickness of the plastic film 13 is less than 4 μm, the yield at the time of coating is remarkably reduced, and when it exceeds 50 μm, the thickness of the circuit board increases, which is not preferable.

  Here, the conditions for attaching the multilayer adhesive film or the coverlay film on the required wiring pattern formed on the metal layer portion on the insulating substrate are not particularly limited, and a conventionally known method is used. Can be applied. For example, a method of hot pressing (heating and pressing) such as heat laminating, a method of roll laminating with a heating roll, and the like can be applied.

  The conditions for using the method of hot pressing (heating and pressurizing) such as the above heat laminating include the first thermosetting adhesive layer 11, the second thermosetting adhesive layer 12, and the plastic film of the coverlay film. 13. What is necessary is just to determine suitably according to heat resistance and melting | fusing temperature (thru | or glass transition temperature etc.), such as a paper by which mold release processing was carried out, and a PET film base separator. Specifically, it is 70 to 130 ° C., preferably 80 to 120 ° C., 0.5 to 5 MPa, preferably 1 to 3 MPa, and thermocompression bonding (thermal lamination) in the range of 5 to 120 seconds, preferably 10 to 60 seconds. ) Is desirable. Here, when it is less than 70 ° C., the adhesive layer does not adhere, and when it exceeds 130 ° C., the PET separator may be deformed. If it is less than 0.5 MPa, the adhesive layer does not adhere, and if it exceeds 5 MPa, the amount of the adhesive flowing out to the opening may increase. If it is less than 5 seconds, the adhesive layer does not adhere, and if it exceeds 120 seconds, the amount of the adhesive flowing out to the opening portion may increase. In addition, the conditions in the case of using the method of roll laminating with a heating roll can be performed under substantially the same conditions as in the case of using the method of hot pressing (heating and pressurizing) such as the above-mentioned thermal lamination.

The multilayer adhesive film of the present invention has a first thermosetting adhesive layer having an adhesive strength to a plastic film of 3 N / 10 mm (23 ° C.) or more and an adhesive strength to a smooth surface of the metal foil of 3 N / 10 mm (23 ° C. ) A multilayer adhesive film having at least the second thermosetting adhesive layer as described above in the outer layer. The plastic film is preferably a polyimide film, and the metal foil is preferably a copper foil. In order to increase the adhesive strength to a plastic film to 3 N / 10 mm (23 ° C.) or more, it is achieved by increasing the elastomer or rubber component and increasing the flexibility to make it softer, or by reducing the glass transition temperature. . Moreover, adhesive force improves that it is an elastomer or rubber component containing an epoxy group.
On the other hand, in order for the adhesive strength to the smooth surface of the metal foil to be 3 N / 10 mm (23 ° C.) or more, many polymer compounds having polar functional groups, hydroxyl groups, carboxyl groups, carbonyl groups, epoxy groups, amino groups, etc. This is achieved by blending. The smooth surface of the metal foil is a smooth surface that has not been roughened and is a shining surface of the copper foil. Usually, the adhesive strength to the metal surface is sufficient, so it is necessary to increase the adhesive strength to the plastic film, and the inorganic filler that lowers the adhesive strength should be added to the second thermosetting adhesive layer side. Is preferred.

  The multilayer adhesive film of the present invention is characterized in that the melt viscosity at the time of heat bonding of the second thermosetting adhesive layer is higher than that of the first thermosetting adhesive layer. The second thermosetting adhesive layer side is an adhesive layer excellent in adhesiveness to the metal foil, and the metal foil is processed to form irregularities corresponding to the thickness of the metal foil. The adhesive layer must fill in the irregularities, but bubbles are easily formed due to the irregularities, and voids are easily formed in the adhesive layer. This void expands at the soldering temperature and causes blistering and peeling, reducing the function as a circuit and reducing the reliability. For this purpose, the second thermosetting adhesive layer on the metal layer side is effective in generating voids when the melt viscosity at the time of heat-bonding is increased to extrude the uneven air of the metal circuit. A more preferable result was obtained when the difference in melt viscosity was 1000 Pa · s or more. The difference in melt viscosity can be changed by the composition of the adhesive used, and the melt viscosity should be increased by using a resin with a high molecular weight, using a rubber or elastomer component to increase the amount, or adding a filler. Can do. It is effective to use a combination of these. The upper limit of the melt viscosity is 10,000 Pa · s due to the fluidity of the adhesive layer.

  In the multilayer adhesive film of the present invention, it is preferable to provide a third thermosetting adhesive layer between the first thermosetting adhesive layer and the second thermosetting adhesive layer. It is effective when a thick adhesive layer is used. In the present invention, the first thermosetting adhesive layer having sufficient adhesion to the plastic film and the second thermosetting adhesive layer having sufficient adhesion to the smooth surface of the metal foil are used. Since the adhesive force is effective even when the thickness is small, the first thermosetting adhesive layer and the second thermosetting adhesive layer are thinned, and the third thermosetting adhesive layer is provided therebetween. The third thermosetting adhesive layer is relatively inferior in adhesiveness but has improved heat properties such as heat resistance and thermal expansion, and these have low or high performance against bending and pulling. An adhesive layer can also be formed. It may be effective for stress relaxation and warping. Furthermore, an adhesive layer that improves electrical properties such as insulation performance may be formed to increase electrolytic corrosion and insulation resistance. The adhesive layer as described above is roughened or replaced with a film that has been subjected to primer treatment to increase the adhesive force, and the first thermosetting adhesive layer is provided on one side and the second thermosetting adhesive is provided on the other side. A layer may be formed.

The multilayer adhesive film of the present invention is preferably one in which one of the first thermosetting adhesive layer and the second thermosetting adhesive layer is colored. The multilayer adhesive film is composed of at least two adhesive layers. If the first and second layers are light and transparent, there may be confusion when manufacturing the multilayer adhesive film. Since the multilayer adhesive film with a two-layer structure is thin, it is difficult to distinguish between the multilayer adhesive film with the first layer provided on the separator and the second layer with the second layer. Furthermore, there are cases where the same adhesive layer is formed or a product is formed with only one adhesive layer. If the adhesive layer is colored, the distinction as to whether or not the adhesive layer as described above is formed becomes clear and trouble does not occur. Further, by coloring, defects such as repellency of the adhesive layer can be visually recognized, and it can be used while avoiding the location, and the product yield is improved.
Coloring is achieved by blending dyes and pigments into the adhesive. It is preferable to select and use those that do not affect the properties of the adhesive. In many cases, those that are usually used can be used because they can be colored in a small amount. Examples include dyes such as fuchsin, crystal violet, methyl orange, Nile Blue 2B, Victoria Piure Blue, Malachite Green, Night Green B, and Spiron Blue, and pigments such as carbon black and iron oxide, and inorganic fillers as pigments It can also be used as an alternative to. In this case, even when the combination of the adhesive layer with the filler used and the adhesive layer not used and the filler are used, the type may be different if the amount is different.

  The effects of the present invention will be specifically described using the following examples and comparative examples.

Example 1
(1) Preparation of solution of first thermosetting adhesive layer For 60 parts by weight of acrylic rubber SG-P3 (manufactured by Nagase ChemteX; number average molecular weight 250,000) containing an epoxy group as a functional group as an elastomer or rubber, 20 parts by weight of cresol novolac type epoxy resin YDCN-703 (manufactured by Tohto Kasei Co., Ltd.) as a thermosetting resin, 20 parts by weight of resol type phenolic resin Hitanol H2181 (manufactured by Hitachi Chemical Co., Ltd.), as a curing agent 0.6 parts by weight of dicyandiamide was dissolved and dispersed in methyl ethyl ketone to obtain an adhesive composition solution that became a first thermosetting adhesive layer having a nonvolatile content of 20% by weight.

(2) Preparation of solution of second thermosetting adhesive layer Thermosetting with respect to 60 parts by weight of acrylic rubber WS023DR (manufactured by Nagase ChemteX; number average molecular weight 110000) containing carboxyl group as a functional group as an elastomer or rubber 20 parts by weight of a cresol novolac type epoxy resin YDCN-703 (manufactured by Tohto Kasei Co., Ltd.) as a functional resin, 20 parts by weight of a resol type phenolic resin Hitanol H2181 (manufactured by Hitachi Chemical Co., Ltd.), and dicyandiamide 0 as a curing agent .6 parts by weight, 80 parts by weight of aluminum hydroxide Heidilite H42M (manufactured by Showa Denko KK) as an inorganic filler was dissolved and dispersed in methyl ethyl ketone to give a solution having a nonvolatile content of 20% by weight. This solution was adjusted to a particle size of 5 μm or less using a ball mill, and sufficiently dispersed to prepare an adhesive composition solution that became a second thermosetting adhesive layer.

(3) Production of Multilayer Adhesive Film As the first thermosetting adhesive layer 11, a 98 μm-thickness release-based paper-based separator (alkyd release agent / PET (thickness 16 μm) / quality paper / PET (thickness 16 μm)) is coated with the solution of the adhesive composition obtained in the above (1) so that the thickness of the adhesive layer 11 after drying is 20 μm, and 100 ° C. in a hot air dryer, Dried for 5 minutes. Subsequently, as a second thermosetting adhesive layer 12, a 50 μm-thickness release-treated PET film-based separator (alkyd release agent / PET (thickness 50 μm)) is dried on the adhesive layer. The adhesive composition solution obtained in the above (2) was applied so that the thickness of 12 was 20 μm, and dried in a hot air dryer at 100 ° C. for 5 minutes. The obtained two adhesive layers 11 and 12 were laminated by thermal lamination (100 ° C., 2 MPa, laminating time 30 seconds) to obtain a multilayer adhesive film 14. The resulting multilayer adhesive film 14 was evaluated for the following characteristics. The second thermosetting adhesive layer contained an inorganic filler and was milky white. The first thermosetting adhesive layer was light orange, and these layers were easily distinguished.

(Characteristic evaluation)
(4) Adhesiveness The multilayer adhesive films 14 having different adhesive strengths were bonded to the polyimide surface of a copper-clad laminate formed of a polyimide film having a thickness of 25 μm and a copper foil A having a thickness of 35 μm. At this time, after releasing the release-processed paper-based separator of the multilayer adhesive film 14, the surface (adhesive layer 11 side) that sufficiently adheres to the plastic film of the multilayer adhesive film 14 is the polyimide of the laminate. It was bonded to the surface (bonding conditions; thermal lamination, 100 ° C., 2 MPa, 30 seconds). Subsequently, the PET film base separator from which the release treatment of the multilayer adhesive film 14 was peeled off, and then the surface (adhesive layer 12 side) that sufficiently adheres to the metal foil of the multilayer adhesive film 14 was laminated with copper. Bonded to the copper foil surface (smooth surface) of a plate (copper-clad laminate formed of a 35-μm-thick copper foil and a 25-μm-thick polyimide base film) (bonding conditions; thermal lamination, 100 C., 2 MPa, 30 seconds). Next, a press temperature of 170 ° C., a pressure of 2.0 MPa, and a heat pressure bonding for 60 minutes were used to form test pieces, and the adhesive strength was evaluated. The obtained results are shown in Table 1 below.

(5) Flow-out property The first thermosetting adhesive layer side of the multilayer adhesive film 14 having adhesive layers with different adhesive forces is bonded to a polyimide film having a thickness of 25 μm, and a coverlay film (in FIG. 2) 10). At this time, the surface of the multilayer adhesive film 14 that is sufficiently adhered to the plastic film (the first thermosetting adhesive layer adhesion) after the release of the paper-based separator of the multilayer adhesive film 14 is peeled off. The agent layer 11 side) was bonded to a polyimide film (bonding conditions; thermal lamination, 100 ° C., 2 MPa, 30 seconds). Subsequently, after the release-treated PET film-based separator of the multilayer adhesive film 14 is peeled off, the surface that is sufficiently adhered to the metal foil of the multilayer adhesive film 14 (adhesion that is the second thermosetting adhesive layer) Copper layer of copper-clad laminate having a required wiring pattern (copper-clad laminate formed of a 35 μm-thick copper foil wiring pattern and a 25 μm-thick polyimide substrate film) It was bonded to the foil surface (wiring pattern surface) (bonding conditions; thermal lamination, 100 ° C., 2 MPa, 30 seconds). Next, thermocompression bonding was performed at a press temperature of 170 ° C., a pressure of 2.0 MPa, and a time of 60 minutes, and the amount of flow from the end portion was evaluated. The obtained results are shown in Table 1 below.
(6) Melt Viscosity Measurement Method Melt viscosity η is obtained by thermocompression bonding the prepared adhesive film at a temperature of 170 ° C., a pressure of 9.8 × 10 ⁶ Pa, and an hour of 1 minute, and a diameter of 1.0 mm and a length of 1.0 mm The adhesive film outflow Q (cm ³ / s) from the stainless steel die was measured, and calculated from the following formula.
η = πD ⁴ P / 128LQ × 10 ⁻³ (Pa / s)
D: Die hole diameter (mm) P: Pressure (Pa) L: Die length (mm) Q: Outflow amount (cm ³ / s) The results obtained are shown in Table 1 below.

Example 2
In Example 1, when the first thermosetting adhesive layer 11 was produced, an adhesive composition solution containing 20 parts by weight of aluminum hydroxide Heidilite H42M (manufactured by Showa Denko KK) was used, Example 1 except that a solution of an adhesive composition containing 40 parts by weight of aluminum hydroxide Heidilite H42M (manufactured by Showa Denko KK) was used when producing the second thermosetting adhesive layer 12. As well as. The characteristic evaluation (adhesiveness, flowability) results of the obtained multilayer adhesive film 14 are shown in Table 1 below.

Comparative Example 1
In Example 1, when producing the 2nd thermosetting adhesive bond layer 12, it implemented except having used the solution of the adhesive composition which does not use Heidilite H42M (made by Showa Denko KK) of aluminum hydroxide. Performed as in Example 1. The characteristic evaluation (adhesiveness, flowability) results of the obtained multilayer adhesive film 14 are shown in Table 1 below.

Comparative Example 2
In Example 1, when producing the first thermosetting adhesive layer 11, a solution of an adhesive composition in which 80 parts by weight of aluminum hydroxide Heidilite H42M (manufactured by Showa Denko KK) was used, As the first thermosetting adhesive layer 11, a solution of the adhesive composition was applied so that the thickness of the adhesive layer after drying was 40 μm, and dried in a hot air drier at 100 ° C. for 5 minutes to form a single layer This was carried out in the same manner as in Example 1 except that the adhesive film (consisting of the adhesive layer 11) was used. The characteristic evaluation (adhesiveness, flowability) results of the obtained adhesive film are shown in Table 1 below.

Comparative Example 3
In Example 1, when producing the second thermosetting adhesive layer 12, a solution of an adhesive composition in which 80 parts by weight of aluminum hydroxide Heidilite H42M (manufactured by Showa Denko KK) was used, As the second thermosetting adhesive layer 12, a solution of the adhesive composition was applied so that the thickness of the adhesive layer after drying was 40 μm, and dried in a hot air dryer at 100 ° C. for 5 minutes. This was carried out in the same manner as in Example 1 except that the adhesive film (consisting of the adhesive layer 12) was used. The characteristic evaluation (adhesiveness, flowability) results of the obtained adhesive film are shown in Table 1 below.

  The number of parts (parts by weight) of the solution of the adhesive composition used for forming each adhesive layer in Table 1 represents the ratio by weight of the active ingredient excluding the solvent.

  The determination of adhesiveness in Table 1 was performed using an autograph and evaluated as follows. All were performed on 5 samples and the values were averaged.

The test piece was processed to a width of 10 mm and peeled at a 90 ° angle in a 23 ° C atmosphere. The peeling speed was 50 mm / min.
The case where the adhesive force to the smooth surface of the copper foil exceeded 3N / 10 mm was evaluated as “◯”, and the case where the adhesive force was 3 N / 10 mm or less was evaluated as “x”.
Moreover, the case where the adhesive force with respect to a polyimide film exceeded 3N / 10mm was evaluated as "(circle)", and the case where the adhesive force was 3N / 10mm or less was evaluated as "*".

  The determination of the flowability (from the end) in Table 1 was performed using a caliper and evaluated in two stages as follows. All were performed for 5 samples.

“◯”: When the longest portion of the flow-out portion is 100 μm or less.
“×”: When the longest portion of the flow-out portion exceeds 100 μm.

  In Comparative Example 1, the filler was removed from the second thermosetting adhesive layer of Example 1, thereby increasing the fluidity of the adhesive layer and deteriorating the flowability. Comparative Example 2 is a single layer adhesive film in which the amount of inorganic filler in the formulation of Example 2 is 40 to 80 parts by weight, but the adhesive strength to polyimide is good, but the metal foil The adhesive strength with respect to the copper foil was deteriorated. In Comparative Example 3, only the second thermosetting adhesive layer used in Example 1 was used as a single-layer adhesive film, but the adhesion to polyimide was good but the adhesion to copper foil was poor. . On the other hand, an adhesive layer (first thermosetting adhesive layer) excellent in adhesion to a smooth surface of a metal foil and an adhesive layer (second thermosetting adhesive layer) excellent in adhesion to a plastic film ), And a multi-layer adhesive film in which an adhesive is formed on the adhesive layer side, which has excellent adhesion, the adhesiveness to metal foil and polyimide film is good, and the adhesive has a controlled flowability. it can.

(Example 3)
After using the multilayer adhesive film 14 produced in Example 1 and peeling off the PET film-based separator on the side of the second thermosetting adhesive layer of the multilayer adhesive film 14 on the 18 μm thick copper foil. Then, it was bonded to a copper foil surface to obtain a multilayer adhesive film with a copper foil (bonding conditions; thermal lamination, 100 ° C., 2 MPa, 30 seconds). Next, on both sides of the printed circuit board on which both sides of the glass epoxy resin double-sided copper-clad laminate board (MCL E-679, thickness 0.8 mm, Tg 175 ° C., manufactured by Hitachi Chemical Co., Ltd.) are applied, After peeling off the release-treated PET film-based separator on the first thermosetting adhesive layer side of the multilayer adhesive film with copper foil, the lamination conditions: thermal lamination, 100 ° C., 2 MPa, lamination for 30 seconds . And the press temperature of 170 degreeC, the pressure of 2.0 Mpa, and thermocompression bonding for 60 minutes were performed, and the 4 layer multilayer board which has a copper foil on the surface was produced. A photosensitive resin film was laminated on the copper foil surface of the multilayer board, and a circuit pattern was formed by a conventional method using a negative pattern mask. The resulting four-layer multilayer printed circuit board was well circuit-formed. This multilayer printed circuit board was cut to a size of 50 mm square with a diamond cutter and allowed to flow in a solder bath at 260 ° C. for 60 seconds. There was no blistering or circuit peeling due to solder, and no delamination, showing good adhesion.

  As is apparent from the above description, the adhesive layer that sufficiently adheres to the metal foil and the adhesive layer that sufficiently adheres to the plastic film as the adhesive layers of the adhesive film and coverlay film are the outermost layers, respectively. By providing an adhesive film layer formed by laminating at least two layers, a multilayer adhesive film capable of exerting sufficient adhesive force against two different types of materials, a metal foil and a plastic film, a coverlay film, A multilayer adhesive film with a copper foil can be provided.

It is the section schematic diagram showing the multilayer adhesive film of the present invention typically. It is the cross-sectional schematic which represented typically the coverlay film of this invention, and the structure of the multilayer circuit board in which the circuit pattern is formed. It is the cross-sectional schematic which represented typically the multilayer adhesive film with a copper foil of this invention.

Explanation of symbols

10 Coverlay film,
DESCRIPTION OF SYMBOLS 11 1st thermosetting adhesive layer 12 2nd thermosetting adhesive layer 13 Plastic film 14 Multilayer adhesive film 15 Circuit pattern 16 Base film 17 Insulating substrate 18 Multilayer circuit board 19 Copper foil 20 Multilayer adhesive film with copper foil

Claims (11)

The first heat curable adhesive layer having an adhesive strength to a plastic film of 3 N / 10 mm (23 ° C.) or higher and the second heat having an adhesive strength to a smooth surface of the metal foil of 3 N / 10 mm (23 ° C.) or higher. A multilayer adhesive film having at least an outer layer having a curable adhesive layer. The multilayer adhesive film according to claim 1, wherein the plastic film is a polyimide film. The multilayer adhesive film according to claim 1 or 2, wherein the metal foil is a copper foil. The multilayer according to any one of claims 1 to 3, wherein the thermosetting adhesive layer contains (i) an elastomer or rubber, (ii) a thermosetting resin, (iii) a curing agent, and (iv) an inorganic filler. Adhesive film. (I) The multilayer adhesive film according to claim 4, wherein the elastomer or rubber is acrylic rubber. The multilayer adhesive film according to any one of claims 1 to 5, wherein the second thermosetting adhesive layer has a higher melt viscosity at the time of heat bonding than the first thermosetting adhesive layer. The multilayer adhesive film according to claim 6, wherein a difference in melt viscosity at the time of heat bonding between the first thermosetting adhesive layer and the second thermosetting adhesive layer is 1000 Pa · s or more. The multilayer adhesive film according to any one of claims 1 to 7, wherein a third thermosetting adhesive layer is provided between the first thermosetting adhesive layer and the second thermosetting adhesive layer. . The multilayer adhesive film according to any one of claims 1 to 8, wherein an adhesive layer of any one of the first thermosetting adhesive layer and the second thermosetting adhesive layer is colored. The coverlay film which laminated | stacked the plastic film on the 1st thermosetting adhesive layer side of the multilayer adhesive film in any one of Claims 1 thru | or 9. The multilayer adhesive film with a copper foil which laminated | stacked copper foil on the 2nd thermosetting adhesive layer side of the multilayer adhesive film in any one of Claim 1 thru | or 9.

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