JP2007254530A - Laminated adhesive sheet, metal layer-adhered laminated adhesive sheet and circuit substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated adhesive sheet which has heat resistance and flexibility at higher levels, has a low linear expansion coefficient and adhesiveness in specific ranges, and enables to achieve lightening (thinning). <P>SOLUTION: This laminated adhesive sheet is characterized by laminating a layer (a) and a layer (b). The layer (a) : a layer of a thermoplastic resin having a Tg (glass transition point) of 130 to 300°C and a water absorption coefficient of <2%. The layer (b): a layer of a thermosetting polyimide resin having a tensile elastic modulus of ≥5 GPa and a linear expansion coefficient of -3 to 10 ppm/°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention uses a polyimide film having a low linear expansion coefficient in a specific range and excellent in heat resistance as a base film (b), and the surface thereof is laminated with a specific thermoplastic resin layer (a). Adhesive sheet that is a multilayer polyimide film that retains the above-mentioned properties of the material film (b) and has a surface property that is excellent in the adhesive properties possessed by the specific thermoplastic resin layer (a), and an adhesive sheet with a metal layer using the same And a circuit board.

  Polyimide films have very little change in physical properties over a wide temperature range from −269 ° C. to 300 ° C., and therefore, applications and uses in the electric and electronic fields are expanding. In the electric field, for example, it is used for coil insulation of vehicle motors, industrial motors, etc., insulation of aircraft electric wires and superconducting wires. On the other hand, in the electronic field, for example, it is used for a flexible printed circuit board, a base film of a film carrier for semiconductor mounting, and the like. Thus, the polyimide film is widely used in the electrical and electronic fields as a highly reliable film among various functional polymer films. Recently, however, major problems have become apparent with the refinement of the electric and electronic fields. For example, a printed circuit board made of a polyimide film base material in which copper is copper-clad by vapor deposition or plating or the like has a tendency that the adhesive force of the copper layer is lowered due to a change with time and an environmental change, and further peeling occurs.

In addition, ceramic has been conventionally used as a material for base materials of electronic components such as information communication equipment (broadcast equipment, mobile radio equipment, portable communication equipment, etc.), radar, high-speed information processing devices, and the like. A base material made of ceramic has heat resistance, and can cope with an increase in the frequency band (reaching the GHz band) of information communication equipment in recent years. However, ceramics are not flexible and cannot be thinned, so the fields that can be used are limited.
For this reason, studies have been made to use a film made of an organic material as a base material for an electronic component, and a film made of polyimide and a film made of polytetrafluoroethylene have been proposed. A film made of polyimide has excellent heat resistance and has the advantage that the film can be thin because it is tough. However, there are concerns about problems such as low signal strength and signal transmission delay when applied to high-frequency signals. However, the tensile strength at break and the tensile modulus are still insufficient, and the linear expansion coefficient is too large. A film made of polytetrafluoroethylene can handle high frequencies, but the tensile modulus is low, so the film cannot be made thin, the adhesion to metal conductors and resistors on the surface is poor, and the coefficient of linear expansion However, it is problematic in that it is not suitable for the production of a circuit having fine wiring due to a large dimensional change due to temperature change. Thus, a film having sufficient physical properties for a substrate having heat resistance, high mechanical properties, and flexibility has not been obtained yet.
As a polyimide film having a high tensile modulus, a polyimide benzoxazole film made of polyimide having a benzoxazole ring in the main chain has been proposed (see Patent Document 1). A printed wiring board using the polyimide benzoxazole film as a dielectric layer has also been proposed (see Patent Document 2 and Patent Document 3).
Polyimide benzoxazole films consisting of polyimides with these benzoxazole rings in the main chain have improved tensile tensile strength and tensile elastic modulus and are within the range of satisfactory linear expansion coefficients. In spite of its physical properties, it has problems such as insufficient surface properties in terms of adhesion.
Japanese Patent Laid-Open No. 06-56992 Japanese National Patent Publication No. 11-504369 Japanese National Patent Publication No. 11-505184

Various proposals have been made to improve the adhesion of polyimide with excellent physical properties. For example, a polyimide film that has a thermoplastic resin layer on at least one surface of a polyimide film that does not have adhesion (see Patent Document 4), a polyimide film And at least a two-layer film in which a film made of polyamide resin is laminated (see Patent Document 5).
Even though those with a thermoplastic resin layer on these polyimide films can be satisfied in improving the adhesiveness, the low heat resistance of these thermoplastic resins will ruin the heat resistance of the folded polyimide film. Had a trend.
Japanese Patent Laid-Open No. 09-169088 JP 07-186350 A

    The present invention has a mechanical expansion characteristic of a polyimide benzoxazole film having a low linear expansion coefficient in a specific range and excellent heat resistance, and is not found in a conventional adhesive sheet having improved surface characteristics such as adhesiveness. PROBLEM TO BE SOLVED: To provide an adhesive sheet with a metal layer using this adhesive sheet and a circuit board using the same.

As a result of intensive studies, the present inventors have found that a specific adhesive layer is laminated on a polyimide film having a specific structure, so that the linear expansion coefficient is in a specific range with a low level, and heat resistance, high frequency compatibility, and flexibility are higher. It is intended to provide an adhesive sheet that achieves insulation reliability and lightness (light thinness) using special polyimide as an insulating layer.
That is, the present invention has the following configuration.
1. The laminated adhesive sheet characterized by the structure by which the following (a) layer and (b) layer are laminated | stacked at least.
(A) Layer: A thermoplastic resin layer having a Tg (glass transition point) of 130 ° C. or more and less than 300 ° C. and a water absorption of less than 2% by mass.
(B) Layer: A layer of thermosetting polyimide resin having a tensile modulus of 5 GPa or more and a linear expansion coefficient of −3 to 10 ppm / ° C.
2. The laminated adhesive sheet according to 1 above, wherein the layer structure is a three-layer structure of (a) / (b) / (a).
3. (B) any one of the above 1-2, wherein the layer is a polyimide having at least a pyromellitic acid residue as a residue of an aromatic tetracarboxylic acid and a diamine residue having a benzoxazole skeleton as a residue of an aromatic diamine Laminated adhesive sheet.
4). The ratio (a) / (b) of the thickness of the (a) layer and the (b) layer is 0.001 to 1, and the thickness of the (b) layer is 3 to 50 μm. Laminated adhesive sheet.
5). The laminated adhesive sheet according to any one of 1 to 4, wherein the linear expansion coefficient in the surface direction of the adhesive sheet is 1 to 15 ppm / ° C.
6). A laminated adhesive sheet with a metal layer, wherein a metal layer is laminated on at least one surface of any one of the laminated adhesive sheets according to any one of 1 to 5.
7). A circuit board using the laminated adhesive sheet according to any one of 1 to 6 above.

  The thermoplastic resin layer having a Tg (glass transition point) of the layer (a) of the present invention of 130 ° C. or more and less than 300 ° C. and a water absorption of less than 2% by mass, and the layer (b) has a tensile elastic modulus of 5 GPa or more, linear An adhesive sheet obtained by laminating a layer of a thermosetting polyimide resin having an expansion coefficient of −3 to 10 ppm / ° C., and having a linear expansion coefficient of 1 to 15 ppm / ° C. in the surface direction of the adhesive sheet, (a) The adhesive sheet in which the ratio (a) / (b) of the thickness of the layer to the (b) layer is 0.001 to 1.0, and the thickness of the (b) layer is 3 to 50 μm is the layer (b) The surface of the polyimide film having high tensile elastic modulus, tensile rupture strength, and low linear expansion coefficient in a specific range is in contact with the metal, etc. It becomes a film with physical properties and excellent points of both, and an adhesive sheet with a metal layer Is effective like the substrate film of the bonding laminate film with a metal foil, for example, very useful as a circuit board such as a flexible printed circuit board.

  The laminated adhesive sheet which is a multilayer polyimide film of the present invention has a structure in which at least (a) layer and (b) layer are laminated, and (a) layer has a Tg (glass transition point) of 130 to 300. The layer (b) is a layer of a thermosetting polyimide resin having a tensile elastic modulus of 5 GPa or more and a linear expansion coefficient of −3 to 10 ppm / ° C. A multilayer polyimide film in which the ratio (a) / (b) of the thickness of the (a) layer and the (b) layer is 0.001 to 1.0 and the thickness of the (b) layer is 3 to 50 μm It is.

The thermosetting polyimide resin having a tensile modulus of 5 GPa or more and a linear expansion coefficient of −3 to 10 ppm / ° C. in the present invention is not particularly limited as long as it has such physical properties. A preferable example is a combination of the following aromatic diamines and aromatic tetracarboxylic acids (anhydrides).
A. A combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid.
B. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
C. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
D. A combination of one or more of the above ABCs.
In particular, A. A combination for producing a polyimide film having an aromatic diamine residue having a benzoxazole structure is preferred.
Benzene used in polyimide benzoxazole mainly composed of polyimide benzoxazole obtained by reacting aromatic diamines having a benzoxazole structure and aromatic tetracarboxylic anhydrides that can be particularly preferably used in the present invention. Examples of aromatic diamines having an oxazole structure include the following compounds.
The polyimide resin layer in the present invention is preferably a film made from these polyimides, and the film has an aromatic tetracarboxylic acid such as pyromellitic acid (including anhydride and derivatives) and a benzoxazole skeleton. A polyamic acid solution that is a precursor of the polyimide is obtained by reacting with a diamine in a solvent, the solution is cast on a support, and dried to obtain a polyimide precursor film (also referred to as a green film). The precursor film can be further heat-treated and imidized to obtain a polyimide film.
A polyimide fine film having a diamine residue having a benzoxazole skeleton as a residue of aromatic diamines will be described in detail below.
Specific examples of aromatic diamines having a benzoxazole structure that are preferably used include the following.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above.
These diamines may be used alone or in combination of two or more. In the present invention, it is preferable to use 70 mol% or more of the aromatic diamine having the benzoxazole structure.

The following diamines can be used without being limited to the diamine. Examples of these diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl] sulfide. Bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl]- 1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'- Diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1 , 1-Bi [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] propane, 1 , 2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl ]propane,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3 Aminophenoxy) benzoyl] benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis 4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3 -Bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl Benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] benzonitrile and some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or hydrogen atoms of alkyl groups or alkoxyl groups. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms partially or wholly substituted with a halogen atom or an alkoxyl group.

Pyromellitic anhydride (Chemical Formula 14) is preferable as an acidic component used for producing a polyimide film preferably used as a film.
Specific examples of aromatic tetracarboxylic acid anhydrides that may be used in addition to pyromellitic acid anhydride as aromatic tetracarboxylic acid (anhydrides) include the following.

These tetracarboxylic acid anhydrides may be used alone or in combination with pyromellitic acid, but these acids may be used in combination, but the use of pyromellitic acid in aromatic tetracarboxylic acids The amount is 80 mol% or more, preferably 90 mol%.
In the present invention, as long as it is less than 30 mol% of the wholly aromatic tetracarboxylic acids, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as appropriate.
Non-aromatic tetracarboxylic dianhydrides include, for example, butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, Cyclobutanetetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2 , 3,5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethyl Cyclohexane-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic acid Dianhydride, 1-ethylcyclohexa -1- (1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropyl Cyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride,

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when polyamic acid is obtained by polymerizing aromatic diamines and aromatic tetracarboxylic acid anhydrides is particularly limited as long as it dissolves both the raw material monomer and the polyamic acid to be produced. Although not preferred, polar organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide Hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols and the like.

The concentration of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is 3.0 to 7.0 dl / g in order to improve the tensile elastic modulus, tensile breaking strength, and tensile breaking elongation. Preferably, 4.0 dl / g or more is more preferable.

In the layer (b) in the present invention, it is preferable to add and contain a lubricant in the polyimide to give fine irregularities on the surface of the layer (film) to improve the adhesion of the layer (film). As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 μm to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.
These fine particles are preferably contained in the range of 0.20 to 2.0% by mass with respect to the film. When the content of the fine particles is less than 0.20% by mass, there is not so much improvement in adhesion, which is not preferable. On the other hand, if it exceeds 2.0% by mass, the surface unevenness becomes too large, and even if the adhesiveness is improved, problems such as a decrease in smoothness remain, which is not preferable.

As a method of forming a polyimide layer (film) from the polyamic acid solution obtained by the polymerization reaction, a green film is obtained by applying the polyamic acid solution on a support and drying, and then subjecting the green film to heat treatment. The method of making it imidation react by providing.
The support on which the polyamic acid solution is applied needs only to have smoothness and rigidity sufficient to form the polyamic acid solution into a film, and a drum or belt whose surface is made of metal, plastic, glass, porcelain, etc. And the like. Among them, the surface of the support is preferably a metal, more preferably stainless steel that does not rust and has excellent corrosion resistance. The surface of the support may be plated with metal such as Cr, Ni, or Sn. The surface of the support can be mirror-finished or processed into a satin finish as necessary. In addition, a polymer film such as a polyethylene terephthalate film or a polyethylene naphthalate film can be used as the support.
Application of the polyamic acid solution to the support includes, but is not limited to, casting from a slit base, extrusion through an extruder, squeegee coating, reverse coating, die coating, applicator coating, wire bar coating, etc. Conventionally known solution coating means can be appropriately used.
A polyamic acid solution is formed into a film to obtain a precursor film (green film), which is imidized to obtain a polyimide film as a layer (b). As a specific imidization method, a conventionally known imidation reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or the polyamic acid solution contains a ring-closing catalyst and a dehydrating agent. In order to obtain a polyimide film in which the difference in surface orientation between the front and back surfaces of the polyimide film is small, a chemical ring closing method can be mentioned in which an imidization reaction is performed by the action of the above ring closing catalyst and dehydrating agent. The thermal ring closure method is preferred.

100-500 degreeC is illustrated as a heating maximum temperature of a thermal ring closure method, Preferably it is 200-480 degreeC. When the maximum heating temperature is lower than this range, it is difficult to close the ring sufficiently, and when it is higher than this range, deterioration proceeds and the film tends to become brittle. A more preferable embodiment includes a two-stage heat treatment in which treatment is performed at 150 to 250 ° C. for 3 to 20 minutes and then treatment is performed at 350 to 500 ° C. for 3 to 20 minutes.
In the chemical ring closure method, after the polyamic acid solution is applied to a support, the imidization reaction is partially advanced to form a self-supporting film, and then imidization can be performed completely by heating. In this case, the condition for partially proceeding with the imidization reaction is preferably a heat treatment for 3 to 20 minutes at 100 to 200 ° C., and the condition for allowing the imidization reaction to be completely performed is preferably 200 to 400 ° C. For 3 to 20 minutes.

In the present invention, the thermoplastic resin used in the thermoplastic resin layer having a Tg (glass transition point) of the layer (a) of 130 ° C. or more and less than 300 ° C. and a water absorption of less than 2% by mass has the specific physical properties described above. There is no particular limitation as long as it is owned. Examples include thermoplastic polyamideimide, thermoplastic polyimide, thermoplastic polyimidesiloxane, thermoplastic polyamideimide siloxane, polyether ether ketone, liquid crystal polymer, polyphenylene oxide, epoxy resin, and one or more resin blends of these resins. An organic or inorganic filler, a flame retardant, etc. can be added to this layer as needed. When Tg (glass transition point) is less than 130 ° C., the heat resistance of layer (b) is often impaired, and when Tg (glass transition point) is 300 ° C. or higher, layer (b) Problems such as difficulty in handling at the time of stacking are increased, which is not preferable.
The linear expansion coefficient in the surface direction of the adhesive sheet in the present invention is 1 to 15 ppm / ° C, preferably 2 to 10 ppm / ° C, more preferably 3 to 8 ppm / ° C.
In order to obtain the physical properties of such an adhesive sheet, it is essential that the (b) layer polyimide has a tensile modulus of 5 GPa or more and a linear expansion coefficient in the plane direction of −3 to 10 ppm / ° C., (a) The adhesive sheet by lamination with the layer retains the physical properties.
If the linear expansion coefficient in the surface direction of the adhesive sheet exceeds this range, the dimensional stability of the adhesive sheet will decrease, and the deviation from the linear expansion coefficient of the metal such as copper constituting the metal layer will increase, causing warpage and peeling. Such problems are likely to occur.
The water absorption rate of the adhesive sheet in the present invention is preferably 2.0% by mass or less, and more preferably 1.5% by mass or less. This can be achieved by setting the water absorption of the thermoplastic resin of the layer (a) to 2.0% or less.
The water absorption of the thermoplastic resin is obtained by immersing a measured product dried at 150 ° C. for 1 hour or more in pure water at 25 ° C. for 24 hours, and increasing the mass before and after that. If the water absorption exceeds this range, bubbles may be generated during lamination processing. Further, the lower limit of the water absorption rate is not particularly limited, and it is theoretically desired to be 0.0% by mass.

The multilayering (lamination) method of the adhesive sheet of the present invention is not particularly limited as long as there is no problem in adhesion between both layers. For example, the method by co-extrusion, the layer (b) of one layer A method of casting the other thermoplastic polyimide polyamic acid solution on the polyimide film and imidizing it, and (b) applying the thermoplastic polyimide polyamic acid solution (a) on the layer by spray coating or the like. Examples include imidization.
The multilayer structure is sufficient if at least the (a) layer and the (b) layer are laminated, and the (a) layer is laminated on the (b) layer, (a) / (b) / (a) A structure in which the (a) layer is laminated on both sides of the (b) layer having the structure of FIG.
The thickness ratio of (a) / (b) in the adhesive sheet of the present invention is the ratio of the thickness of (a) / (b) in the gist of the present invention (even in the case of a three-layer structure (a) Is a total calculation as a single layer) is preferably 0.001 to 1.0, more preferably 0.005 to 0.20. When the thickness ratio of (a) / (b) exceeds 1.0, the mechanical strength is often insufficient or the linear expansion coefficient becomes too large, making it difficult to obtain a predetermined adhesive sheet. On the other hand, if it is less than 0.001, the effect of improving the surface properties is often insufficient. (B) The thickness of the layer mainly responsible for the mechanical strength is preferably 3 to 50 μm. If the thickness is less than 3 μm, the mechanical strength tends to be insufficient, and if it is 50 μm or more, the circuit is light and thin. There are many obstacles.
With these configurations, an adhesive sheet having heat resistance and a linear expansion coefficient in the plane direction of 1 to 15 ppm / ° C. is obtained.

The measurement of the linear expansion coefficient (CTE) in the surface direction in the present invention is as follows.
<Linear expansion coefficient in the surface direction of (b) layer film and adhesive sheet>
About the measurement target film and adhesive sheet, the stretch rate in the MD direction and the TD direction is measured under the following conditions, and the stretch rate / temperature at intervals of 90 ° C. to 100 ° C., 100 ° C. to 110 ° C.,. This was measured up to 400 ° C., and the average value of all measured values from 100 ° C. to 200 ° C. was calculated as CTE (average value). The meanings of the MD direction and the TD direction indicate the flow direction (MD direction; the length direction of the long film) and the width direction (TD direction; the width direction of the long film). The linear expansion coefficient in the plane direction is an average value of values in the MD direction and the TD direction.
Device name: TMA4000S manufactured by MAC Science
Sample length; 10mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

The measurement of the tensile elastic modulus in the present invention is as follows.
<(B) Tensile Elastic Modulus of Layer Film>
A test piece was prepared by cutting a polyimide film to be measured into a strip of 100 mm × 10 mm in the MD direction and the TD direction, respectively. Using a tensile tester (manufactured by Shimadzu Corp., Autograph, model name AG-5000A), the tensile modulus was measured for each of the MD direction and the TD direction under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm. When the distinction between the MD direction and the TD direction is not specified, the value is in the MD direction.

In the adhesive sheet of the present invention, the layer (a) and the layer (b) are provided with a lubricant in the layer to give fine irregularities on the surface of the layer (film), thereby improving the slipperiness of the layer. It is preferable.
As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 μm to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.
In the present invention, the surface of the obtained adhesive sheet (particularly the surface of (a)) is preferably subjected to corona treatment, atmospheric pressure plasma treatment, and vacuum plasma discharge treatment in order to further increase the adhesive force. .

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. The physical property evaluation methods in the following examples are as follows except for the above.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.
2. Layer thickness The thickness was measured using a micrometer (Millitron 1254D, manufactured by Finerfu).
3. The water-absorbing adhesive sheet of the laminated adhesive sheet was cut into about 10 cm × 10 cm and used as a test. First, the test piece is dried in a dry oven at 150 ° C. for 1 hour. Immediately after that, the mass is measured to obtain an initial value, and then the test piece is placed in 25 ° C. ion-exchanged water for 24 hours. The sample was wiped off and reweighed to obtain the water absorption value. The water absorption was determined from the following formula.
(Water absorption) = 100 × {(Water absorption value) − (Initial value)} / (Initial value) [mass%]

[Polymeric acid solution polymerization example 1]
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 500 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole was added. Next, 5000 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then 485 parts by mass of pyromellitic dianhydride was added and stirred at 25 ° C. for 48 hours. A polyamic acid solution was obtained. The reduced viscosity (ηsp / C) was 4.2 dl / g.

[Polymeric acid solution polymerization example 2]
The inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, and then 200 parts by mass of diaminodiphenyl ether was added. Next, after 4200 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 217 parts by mass of pyromellitic dianhydride was added and stirred at 25 ° C. for 5 hours. A polyamic acid solution was obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g.

[Production Example 1]
The polyamic acid solution obtained in Polymerization Example 1 was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (gap: 200 μm, coating width: 1240 mm). ) It was passed through a continuous drying furnace having four drying zones and dried at a temperature of 90 ° C. for 15 minutes for 60 minutes in total.
The polyamic acid film which became self-supporting after drying was peeled from the polyester film, and both ends were cut to obtain respective green films having a thickness of 22 μm and a width of 1200 mm.
The obtained green film was passed through a continuous heat treatment furnace purged with nitrogen while holding both ends with a pin tenter, the first stage was dried at 170 ° C. for 3 minutes, and the temperature was increased at a rate of temperature increase of 4 ° C./second. Then, as the second stage, two-stage heating was performed at 450 ° C. for 7 minutes to advance the imidization reaction. Then, it cooled to room temperature in 5 minutes, and the 15-micrometer-thick polyimide film (F1) which exhibits brown was obtained. The obtained polyimide film had a tensile modulus of 8.2 GPa and a CTE of 2.1 ppm.

[Production Example 2]
The polyamic acid solution obtained in Polymerization Example 2 was coated on a non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (gap: 200 μm, coating width: 1240 mm). ) It was passed through a continuous drying furnace having four drying zones, dried at a temperature of 90 ° C. for 15 minutes each for a total of 60 minutes, and a polyimide film (F2) having a thickness of 15 μm and showing a brown color in the same manner as in Production Example 1 below. Obtained. The resulting polyimide film had a tensile modulus of 2.8 GPa and a CTE of 29 ppm.

[Adjustment of thermoplastic resin A1]
A polyether ether ketone resin (PEEK381G manufactured by Victrex Co., Ltd.) is used with a heat press machine (SA303 type: manufactured by Tester Sangyo Co., Ltd.) using a SUS 5 μm spacer at a set temperature of 370 ° C. and a pressure of 2 MPa for 1 minute. By pressing, a PEEK film (thermoplastic resin A1) having a thickness of 3 μm was obtained. Table 1 shows the physical properties of this thermoplastic resin.

[Adjustment of thermoplastic resin A2]
Polyether ether ketone resin [PECK381G manufactured by Victrex Co., Ltd.] using a 20 μm spacer made of SUS with a heat press machine (SA303 type: manufactured by Tester Sangyo Co., Ltd.) at a set temperature of 370 ° C. and a pressure of 2 MPa for 1 minute. A PEEK film (thermoplastic resin A2) having a thickness of 12 μm was obtained by pressing. Table 1 shows the physical properties of this thermoplastic resin.

[Adjustment of thermoplastic resin B]
A polyimide siloxane resin (UPA8517C: manufactured by Ube Industries) was coated on a non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using an applicator, and dried at a temperature of 90 ° C. for 15 minutes. As a result, a self-supporting polyamic acid film was obtained. This film is fixed with a metal frame, heated from room temperature to 200 ° C. at a rate of temperature increase of 5 ° C./min, and held at 200 ° C. for 60 minutes to give a thermoplastic polyimide siloxane film having a thickness of 3 μm (thermoplastic resin B) Got. Table 1 shows the physical properties of this thermoplastic resin.

[Adjustment of thermoplastic resin C]
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 200 parts by mass of diphenyl ether was added. Next, after 4200 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 217 parts by mass of benzophenonetetracarboxylic dianhydride was added and stirred at 25 ° C. for 5 hours. A tonic polyamic acid solution was obtained. This reduced viscosity (ηsp / C) was 3.4 dl / g.
The obtained polymer solution is coated with a gap of 40 μm on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using an applicator (then dried at a temperature of 90 ° C. for 60 minutes). Thus, a self-supporting polyamic acid film was obtained, which was fixed with a metal frame, heated from room temperature to 350 ° C. at a heating rate of 25 ° C./min, and kept at 350 ° C. for 10 minutes. A thermoplastic polyimide film (thermoplastic resin C) having a thickness of 3 μm was obtained, and the physical properties of this thermoplastic resin are shown in Table 1.

[Adjustment of thermoplastic resin D]
After the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 200 parts by mass of 1,3-bis (4-aminophenoxy) benzene was added. Next, after 4200 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 217 parts by mass of benzophenonetetracarboxylic dianhydride was added and stirred at 25 ° C. for 5 hours. A tonic polyamic acid solution was obtained. This reduced viscosity (ηsp / C) was 2.4 dl / g.
The obtained polymer solution is coated with a gap of 40 μm on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using an applicator (then dried at a temperature of 90 ° C. for 60 minutes). Thus, a self-supporting polyamic acid film was obtained, which was fixed with a metal frame, heated from room temperature to 350 ° C. at a heating rate of 25 ° C./min, and kept at 350 ° C. for 10 minutes. A thermoplastic polyimide film (thermoplastic resin D) having a thickness of 3 μm was obtained, and the physical properties of this thermoplastic resin are shown in Table 1.

[Adjustment of thermoplastic resin E]
In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser and a distillation tube, 38 parts by mass of toluene 100 parts by mass, nitrile butadiene rubber, NIPOL 1001 (manufactured by Nippon Zeon Co., Ltd., nitrile content 40.5% by mass) Similarly, 4 parts by mass of NIPOL 1312 (manufactured by Nippon Zeon Co., Ltd., nitrile content: 31 to 36% by mass) was charged and dissolved, followed by 58 parts by mass of phenol novolac epoxy resin BREN (manufactured by Nippon Kayaku Co., Ltd.), imidazole compound Of Curazole 2E4MZ-CN (manufactured by Shikoku Kasei Co., Ltd.) was added and mixed well to obtain an adhesive solution. Using an applicator, the adhesive solution was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) with a gap of 40 μm, and then dried at a temperature of 90 ° C. for 60 minutes. A 3 μm self-supporting thermoplastic resin E film was obtained.
The sample for evaluating physical properties of E was adjusted by curing at 160 ° C. for 2 hours with a heat press. Table 1 shows the physical properties of this thermoplastic resin.

[Example 1]
(B) The polyimide film (F1) as the layer and the thermoplastic resin A1 film as the (a) layer were laminated together at 150 ° C., 5 MPa, 0.5 m / min with a laminator. The laminate was heat-treated at 200 ° C., 10 MPa, 60 min by heat pressing to produce an adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this adhesive sheet are shown in Table 2.

[Example 2]
The polyimide film (F1) as the (b) layer and the thermoplastic resin B film as the (a) layer were laminated with a laminator at 250 ° C., 5 MPa, 0.5 m / min. The laminated body was heat-treated with a heat press at 250 ° C., 10 MPa, and 60 min to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this laminated adhesive sheet are shown in Table 2.

Example 3
(B) A polyimide film (F1) as a layer and a thermoplastic resin C film as a layer (a) were laminated at 300 ° C., 5 MPa, 0.5 m / min with a laminator. The laminated body was heat-treated by heat pressing under the conditions of 300 ° C., 20 MPa, and 60 min to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this laminated adhesive sheet are shown in Table 2.

Example 4
A polyimide film (F1) is mounted on a continuous sputtering apparatus, a frequency of 13.56 MHz, an output of 400 W, a gas pressure of 0.8 Pa, a nickel-chromium (chromium content 10%) alloy target, and in an argon atmosphere. A nickel-chromium alloy film having a thickness of 50 mm was formed at a rate of 10 mm / sec by RF sputtering. Subsequently, copper was vapor-deposited at a rate of 100 liters / second to form a copper thin film having a thickness of 0.3 μm. Thereafter, this film is cut out to 250 mm × 400 mm, fixed to a plastic frame, and a thick copper plating layer having a thickness of 5 μm is formed on the copper thin film using a copper sulfate plating bath. A film (metallized film) was obtained.
(B) A metallized polyimide film as a layer and a thermoplastic resin A1 film as a layer (a) were laminated with a laminator at 150 ° C., 5 MPa, and 0.5 m / min. The laminated body was heat-treated at 200 ° C., 10 MPa, 60 min by heat pressing to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (c). The evaluation results of this laminated adhesive sheet are shown in Table 2.

[Comparative Example 1]
(B) The polyimide film (F1) as the layer and the thermoplastic resin D film as the (a) layer were laminated together at 250 ° C., 5 MPa, 0.5 m / min with a laminator. The laminated body was heat-treated with a heat press under the conditions of 250 ° C., 20 MPa, and 60 min to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this laminated adhesive sheet are shown in Table 2.

[Comparative Example 2]
(B) The polyimide film (F1) as a layer and the thermoplastic resin E film as a layer (a) were laminated together at 100 ° C., 5 MPa, 0.5 m / min with a laminator. The laminated body was heat-treated by heat press at 160 ° C., 10 MPa, and 120 min to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this laminated adhesive sheet are shown in Table 2.

[Comparative Example 3]
(B) The polyimide film (F2) as the layer and the thermoplastic resin A1 film as the (a) layer were laminated together at 150 ° C., 5 MPa, 0.5 m / min with a laminator. The laminated body was heat-treated at 200 ° C., 10 MPa, 60 min by heat pressing to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this laminated adhesive sheet are shown in Table 2.

[Comparative Example 4]
The polyimide film (F1) as the (b) layer and the thermoplastic resin A2 film as the (a) layer were laminated with a laminator at 150 ° C., 5 MPa, and 0.5 m / min. The laminated body was heat-treated at 200 ° C., 10 MPa, 60 min by heat pressing to produce a laminated adhesive sheet having a layer configuration of (a) / (b) / (a). The evaluation results of this laminated adhesive sheet are shown in Table 2.

(Manufacture of copper-clad laminated adhesive sheet and evaluation of adhesive strength)
The roll surface temperature was set to 178 ° C. by heating using a silicone rubber roll laminating machine of the roll internal heating and external heating combined system. The laminated adhesive sheet produced in [Example 1] is passed between rolls, and an electrolytic copper foil (USLP-SE: manufactured by Nihon Electrolysis Co., Ltd.) having a thickness of 12.5 μm is supplied from both sides of the laminated adhesive sheet. A double-sided copper-clad laminate film made of polyimide film / copper foil was obtained. Similarly, the film used in each Example and Comparative Example and the copper foil were laminated at a temperature 30 ° C. higher than the glass transition temperature of the thermoplastic resin layer to produce a double-sided copper-clad laminate film. In the laminated adhesive sheet with a copper layer of Example 4, only the surface of the thermoplastic resin layer was laminated with a copper foil to prepare a copper-clad laminated film.
The copper-clad laminate adhesive sheet produced above was slit to 2 mm width, and first peeled to a length that could be chucked with a tensile tester using a cutter knife so that the interface between the copper foil and the adhesive sheet emerged from the end face. . Using a tensile tester (manufactured by Shimadzu Corp., Autograph, model name AG-5000A), a 90 ° peel test was performed at a tensile speed of 50 mm / min. From the obtained chart, the adhesive strength with the copper foil surface, the film surface The adhesive strength of each was read. The evaluation results are shown in Table 3.
(Production of polyimide laminated adhesive sheet and evaluation of adhesive strength)
Instead of the copper foil, a polyimide laminated adhesive sheet was produced using the polyimide film (F1) produced in Production Example 1 under the same conditions as in the production of the copper-clad laminated adhesive sheet. The polyimide laminated adhesive sheet was slit to a width of 2 mm, and was first peeled to a length that could be chucked with a tensile tester using a cutter knife so that the interface between the polyimide and the adhesive sheet emerged from the end face. Using a tensile tester (manufactured by Shimadzu Corp., Autograph, model name AG-5000A), a 90 ° peel test was performed at a tensile speed of 50 mm / min. From the obtained chart, the adhesive strength with the copper foil surface, the film surface The adhesive strength of each was read. The evaluation results are shown in Table 3.

(Manufacture of multilayer substrate 1)
Both surfaces of the 15 μm-thick polyimide film used in Example 1 were plasma-treated in a gas of argon / oxygen = 85: 15 (mass ratio), and nickel chrome (80:20 mass parts ratio) was formed on the entire surface. ) Was sputtered to a thickness of 100 mm, and then copper was similarly sputtered to a thickness of 1000 mm to produce a double-sided conductive film.
A negative resist with a film thickness of 6 μm is formed on one side of the produced double-sided conductive film using a liquid resist, copper is thickened with a thickness of 3 μm by electroplating, the resist is peeled off, and a conductive layer is formed by flash etching and nickel remover. Was removed, and a test circuit pattern of 5 cm × 5 cm, which was assumed to be mounted on an LCD driver including fine lines with a line spacing / line width of 10 μm / 10 μm, was formed. Similarly, a square pattern of 5 mm square was formed in a lattice pattern with a pattern spacing of 0.5 mm on the back surface, and a large number of test circuit boards were produced in the same manner. The area density of the pattern is 50% on both sides.
Three prepared test circuit boards were prepared, the laminated adhesive sheet obtained in Example 1 was sandwiched between the upper and lower substrates, and lamination was performed by hot pressing to produce a seven-layer test multilayer board.
The following evaluations, such as adhesive strength, were performed using the produced test multilayer substrate.
Similarly, a large number of test circuit boards were produced in the same manner using the films used in the examples and comparative examples. Three test circuit boards were prepared, and the same laminated adhesive sheet of each example and comparative example was sandwiched between the upper and lower sides of each board, and laminated by hot pressing to produce a seven-layer test multilayer board. did.

(Manufacture of multilayer substrate 2)
Photoresist (FR-200, manufactured by Shipley Co., Ltd.) was applied to the copper layer surface of the laminated adhesive film with a copper layer produced in Example 4 and dried and then closely exposed with a glass photomask, and further with a 1.2 mass% KOH aqueous solution. Developed. Next, with an etching line of cupric chloride containing HCl and hydrogen peroxide, etching is performed at 40 ° C. with a spray pressure of ² kgf / cm ² , and an LCD driver is mounted that includes fine lines with a line spacing / line width of 25 μm / 25 μm. A test circuit pattern of 5 cm × 5 cm that was supposed to be used was formed.
5 layers of this test pattern as inner layer members in the same direction and 2 sheets of double-sided conductive films made as the outermost layer (manufacture of multilayer substrate 1) are sandwiched between the upper and lower surfaces and laminated by hot pressing for 7-layer testing A multilayer substrate was produced.

(Evaluation of multilayer board)
1. Appearance Observation on a surface plate was visually observed for warp, distortion, blistering, and other appearance abnormalities by magnifying observation with a 10 × stereo microscope.
2. Cross-sectional observation The test multi-layer substrate was cut in a direction in which the cross-section in the width direction of the fine line pattern appeared, embedded in resin, polished on the end face, magnified and observed with a microscope, and the following points were evaluated.
(1) Embedding property between circuits The presence or absence of voids was observed at 100 points between the lines.
The evaluation results are shown in Table 3 below.
3. Acceleration test The test substrate was left in a PCT environment (121 ° C., 100% RH, 2 atom, 168 hr), then immersed in a 300 ° C. solder bath for 1 minute, and a sample was taken out. The appearance was visually observed. If foaming or swelling of the adhesive sheet was confirmed, it was judged as bad. If it was not confirmed, it was judged good.
4). Drill workability A through-hole with a hole diameter of φ250 μm was produced using an NC drill machine on a test substrate. The rotation speed of the drill is 12000 rpm. After forming the through hole, it was embedded with an epoxy resin, and the inside of the hole was polished at the end face, and then enlarged and observed with a microscope. The case where a step was not confirmed at the interface between the thermoplastic resin layer and the thermosetting polyimide layer inside the through hole was indicated as “◯”, the case where a small step was seen as “Δ”, and the case where a large step was seen as “X”. The evaluation results are shown in Table 3.

  The laminated adhesive sheet of the present invention is excellent in bonding with a metal thin film or a metal foil at high temperatures, and is a flexible metal laminated plate having no deformation, warpage, or distortion at high temperatures, for example, as an interlayer insulating layer such as a flexible printed circuit board. Extremely useful, in which the deformation of the polyimide layer (film) of the base material is suppressed during pressurization and heating during the formation of the insulating layer, and (a) the pressure uniformity of the adhesive layer to the adhesive layer And the penetration of the adhesive layer between the circuits can be achieved efficiently. (B) It is possible to ensure heat-resistant insulation by ensuring the insulating layer thickness of the layer, and it is possible to further reduce the total thickness, which is obtained when used for interlayer insulation such as multilayer printed wiring boards. It can achieve miniaturization (lightness and thinness) of multilayer printed wiring boards, etc., and is useful for increasing the functionality, performance, and miniaturization of electronic devices.

Claims (7)

The laminated adhesive sheet characterized by the structure by which the following (a) layer and (b) layer are laminated | stacked at least.
(A) Layer: A thermoplastic resin layer having a Tg (glass transition point) of 130 to 300 ° C. and a water absorption of less than 2 mass%.
(B) Layer: A layer of thermosetting polyimide resin having a tensile modulus of 5 GPa or more and a linear expansion coefficient in the plane direction of −3 to 10 ppm / ° C.   The laminated adhesive sheet according to claim 1, wherein the layer structure is a three-layer structure of (a) / (b) / (a).   The layer (b) is a polyimide having at least a pyromellitic acid residue as an aromatic tetracarboxylic acid residue and a diamine residue having a benzoxazole skeleton as an aromatic diamine residue. The adhesive sheet according to 1.   The ratio (a) / (b) of the thickness of the (a) layer and the (b) layer is 0.001-1, and the thickness of the (b) layer is 3-50 μm. The laminated adhesive sheet according to any one of the above.   The laminated adhesive sheet according to any one of claims 1 to 4, wherein a linear expansion coefficient in a surface direction of the adhesive sheet is 1 to 15 ppm / ° C.   The laminated adhesive sheet with a metal layer which laminated | stacked the metal layer on the at least one surface of the laminated adhesive sheet in any one of Claims 1-5.   A circuit board using the laminated adhesive sheet according to claim 1.