WO2013157565A1

WO2013157565A1 - Thermal adhesive polyimide film, method for producing thermal adhesive polyimide film, and polyimide/metal laminate using thermal adhesive polyimide film

Info

Publication number: WO2013157565A1
Application number: PCT/JP2013/061356
Authority: WO
Inventors: 暢飯泉; 英雄有原; 英治升井; 圭一柳田; 拓郎河内山
Original assignee: 宇部興産株式会社
Priority date: 2012-04-19
Filing date: 2013-04-17
Publication date: 2013-10-24
Also published as: TW201402325A

Abstract

Provided are a thermal adhesive polyimide film that offers excellent heat resistance and excellent adhesiveness to a metal layer, a method for producing the thermal adhesive polyimide film, and a polyimide/metal laminate using the thermal adhesive polyimide film. A multi-layered thermal adhesive polyimide film comprising a thermal adhesive polyimide layer and a heat-resistant polyimide layer layered in contact with the thermal adhesive polyimide layer, the thermal adhesive polyimide film being characterized in that: the thermal adhesive polyimide layer comprises 50 mol% or more 3,3',4,4'-biphenyl tetracarboxylic dianhydride of the total tetracarboxylic dianhydride component, and comprises more than 50 mol% 2,2-bis[4-(4-aminophenoxy) phenyl] propane of the total diamine; and the heat-resistant polyimide layer comprises 50 mol% or more 3,3',4,4'-biphenyl tetracarboxylic dianhydride of the total tetracarboxylic dianhydride component, the peel strength as measured by the method in JIS C6471 being 0.5 N/mm or more.

Description

Heat-sealable polyimide film, method for producing heat-sealable polyimide film, and polyimide metal laminate using heat-sealable polyimide film

The present invention relates to a heat-fusible polyimide film, a method for producing a heat-fusible polyimide film, and a polyimide metal laminate using the heat-fusible polyimide film.

Polyimide films are widely used as substrate materials such as flexible printed boards (FPC) and tape automated bonding (TAB).

In the production of FPC and TAB, as a method of laminating a polyimide film and a copper foil, an adhesive such as an epoxy resin or an acrylic resin can be used.

In addition, as a polyimide film that can be bonded to a copper foil without using an adhesive, Patent Document 1 discloses a polyimide film having a heat-fusible property in which a heat-fusible polyimide layer is laminated on a heat-resistant polyimide layer. Is disclosed.

JP 2004-230670 A

However, with the enhancement of FPC and TAB functions, the heat resistance of the heat-fusible polyimide film and the adhesion between the heat-fusible polyimide film and the metal layer such as copper foil as the adherend are further improved. It was desired.

It is an object of the present invention to provide a heat-fusible polyimide film excellent in heat resistance and adhesiveness to a metal layer, a method for producing the same, and a polyimide metal laminate using the heat-fusible polyimide film. To do.

In order to solve the above-mentioned problems, the present inventors set the types and blending ratios of the tetracarboxylic dianhydride component and the diamine component as the components of the heat-fusible polyimide film, and the conditions for producing the polyimide film. The present invention was completed by earnest examination.

The present invention relates to the following matters.
(1) A multilayer heat-fusible polyimide film comprising a heat-fusible polyimide layer and a heat-resistant polyimide layer laminated in contact with the heat-fusible polyimide layer,
The heat-fusible polyimide layer is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the heat-fusible polyimide layer is a total tetracarboxylic dianhydride component. Among them, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is contained in an amount of 50 mol% or more, and the diamine component of the heat-fusible polyimide layer is 2,2-bis [4 -(4-aminophenoxy) phenyl] propane in excess of 50 mol%,
The heat-resistant polyimide layer is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the heat-resistant polyimide layer is the total tetracarboxylic dianhydride component, Containing 50 mol% or more of 3 ′, 4,4′-biphenyltetracarboxylic dianhydride,
A 18 μm copper foil is superposed on the heat-fusible polyimide layer of the heat-fusible polyimide film, and is higher by 30 ° C. than the glass transition temperature of the heat-fusible polyimide constituting the heat-fusible polyimide layer, and 420 ° C. The polyimide metal laminate obtained by thermocompression bonding with a press pressure of 3 MPa and a press time of 1 minute in the following temperature range has a peel strength measured by the method of JIS C6471 of 0.5 N / mm or more. Heat-sealable polyimide film.
(2) The heat according to (1), wherein the diamine component of the heat-fusible polyimide layer contains 70 mol% or more of 2,2-bis [4- (4-aminophenoxy) phenyl] propane in all diamines. Fusible polyimide film.
(3) The heat-fusible polyimide film according to (1) or (2), wherein the diamine component of the heat-fusible polyimide layer contains 25 mol% or more of paraphenylenediamine in all diamines.
(4) The tetracarboxylic dianhydride component of the heat-fusible polyimide layer is 50% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component. The heat fusion according to any one of (1) to (3) above, comprising at least mol% and comprising 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride in excess of 0 and less than 50 mol%. Conductive polyimide film.
(5) The tetracarboxylic dianhydride component of the heat-fusible polyimide layer is 50% of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component. The heat-fusible polyimide film as described in (4) above, containing at least mol% and containing 10 to 30 mol% of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride.
(6) The heat-fusible polyimide film according to any one of (1) to (5), wherein the diamine component of the heat-resistant polyimide layer contains 50 mol% or more of paraphenylenediamine in all diamines.
(7) A polyimide precursor solution (a) that gives a heat-resistant polyimide layer and a polyimide precursor solution (b) that gives a heat-fusible polyimide layer are cast from an extrusion die on a support and laminated. Forming a thin film-like body, drying the thin-film body at a temperature of 140 ° C. or more to form a self-supporting film, peeling the self-supporting film from the support, and peeling the self-supporting film A method for producing a heat-fusible polyimide film to be heated,
The polyimide precursor solution (a) is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the polyimide precursor solution (a) is all tetracarboxylic dianhydride. In the product component, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is contained in an amount of 50 mol% or more,
The polyimide precursor solution (b) is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the polyimide precursor solution (b) is all tetracarboxylic dianhydride. In the physical component, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is contained in an amount of 50 mol% or more, and the diamine component of the polyimide precursor solution (b) is 2,2- A method for producing a heat-fusible polyimide film, comprising more than 50 mol% of bis [4- (4-aminophenoxy) phenyl] propane.
(8) The method for producing a heat-fusible polyimide film according to (7), wherein the thin film-like body is dried at a temperature of 145 ° C. or higher.
(9) A polyimide metal laminate obtained by laminating a metal layer in contact with the heat-fusible polyimide layer of the heat-fusible polyimide film described in any one of (1) to (6) above.

According to the present invention, a heat-fusible polyimide film having excellent heat resistance and excellent adhesion to a metal layer can be obtained. Moreover, the laminated body (polyimide metal laminated body) with high peeling strength of a polyimide film and a metal layer can be obtained by thermocompression-bonding this heat-fusible polyimide film and metal layers, such as copper foil.

[Heat-bondable polyimide film]
The heat-fusible polyimide film of the present invention is a multilayer heat-fusible polyimide film including a heat-fusible polyimide layer and a heat-resistant polyimide layer laminated in contact with the heat-fusible polyimide layer. In addition, the heat-fusible polyimide film of the present invention is a single-layer heat-fusible polyimide film composed of only a heat-fusible polyimide layer or a multilayer heat-fusing film including a heat-fusible polyimide layer as a surface layer. It is a conductive polyimide film.

Here, “thermal fusion” means that the softening point of the polyimide film surface is less than 350 ° C. The softening point is a temperature at which the object is softened suddenly when heated. The glass transition temperature (Tg) is used for amorphous polyimide, and the melting point is used for crystalline polyimide. In the following, “heat-fusibility” is sometimes referred to as “thermoplastic”. Here, the “heat-sealable polyimide layer” includes “a single-layer heat-sealable polyimide film”.

<Heat-bonding polyimide layer>
The heat-fusible polyimide layer is obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component.
The heat-fusible polyimide layer comprises 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as a tetracarboxylic dianhydride component, and 50 mol% or more of the total tetracarboxylic dianhydride component. Including.
The content of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component is preferably 70 mol% or higher, more preferably 80 mol% or higher, more preferably 90 mol%. More than mol%.
Further, the total tetracarboxylic dianhydride component may contain 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride exceeding 0 and less than 50 mol%, preferably 10 to 30 mol%. Thereby, a polyimide metal laminate having high peel strength can be obtained.
Further, the heat-fusible polyimide layer contains 2,2-bis [4- (4-aminophenoxy) phenyl] propane as a diamine component in an amount exceeding 50 mol% in the total diamine. The content of 2,2-bis [4- (4-aminophenoxy) phenyl] propane in all diamines is preferably 60 mol% or more from the viewpoint of obtaining a polyimide film having excellent heat resistance and low water absorption, which will be described later. More preferably, it is 65 mol% or more, and most preferably 70 mol% or more and 100% or less.

As the tetracarboxylic dianhydride component of the heat-fusible polyimide layer, the above two acid components and other tetracarboxylic dianhydride components can be used in combination. Other tetracarboxylic dianhydride components include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride Bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2 -Bis (3,4-dicarboxyphenyl) propane dianhydride, 1,4-hydroquinone dibenzoate-3,3 ', 4,4'-tetracarboxylic dianhydride and the like. The tetracarboxylic dianhydride components used in combination can be used alone or in combination of two or more.

As the diamine component of the heat-fusible polyimide layer, the above 2,2-bis [4- (4-aminophenoxy) phenyl] propane and another diamine component can be used in combination. Specific examples of the diamine component used in combination include 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 3 , 3′-diaminobenzophenone, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) ) Phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) Phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, and 2,2-bis [4- (3-aminophenoxy) phenyl] propane. Of these, 1,3-bis (4-aminophenoxy) benzene and 1,4-bis (4-aminophenoxy) benzene can be preferably used. Furthermore, 1,3-bis (4-aminophenoxy) benzene is particularly preferred. The diamine component to be used in combination can be used alone or in combination of two or more.

In addition, aromatic diamines such as paraphenylene diamine and metaphenylene diamine, modified products thereof, and aliphatic diamines such as hexamethylene diamine and tetramethylene diamine can be used in combination as long as the characteristics of the present invention are not impaired. Among these, it is preferable to use paraphenylenediamine together. The heat-fusible polyimide layer preferably contains 25% by mole or more of paraphenylenediamine in all diamines. Thereby, the heat resistance of a polyimide metal laminated body further improves, and the peeling strength with a metal layer also becomes high.

<Heat resistant polyimide layer>
The heat-resistant polyimide layer is obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component.
The heat-resistant polyimide contains 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as a tetracarboxylic dianhydride component in an amount of 50 mol% or more in the total tetracarboxylic dianhydride component. Moreover, you may contain another tetracarboxylic dianhydride component.
For example, it contains 50 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride and 1,4-hydroquinone dibenzoate-3,3 ′, 4 It is preferable to include at least one acid component selected from 4′-tetracarboxylic dianhydride. The total amount of these tetracarboxylic dianhydride components is preferably 70 mol% or more, more preferably 80 mol% or more, and more preferably 90 mol% or more in the total tetracarboxylic dianhydride component. It is more preferable.
The diamine component of the heat-resistant polyimide is not particularly limited. For example, paraphenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, m-tolidine, and 4,4′-diaminobenzanilide. It is preferable to include at least one diamine component selected from the above. The total amount of these diamine components is preferably 70 mol% or more, more preferably 80 mol% or more, and more preferably 90 mol% or more in the total diamine components. More preferably, the diamine component of the heat-resistant polyimide contains 70 mol% or more of paraphenylenediamine in the total diamine.

Examples of the combination of an acid component and a diamine component that can provide a heat-resistant polyimide layer include the following.
(1) A combination comprising 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA), paraphenylenediamine (PPD), and, if necessary, 4,4-diaminodiphenyl ether (DADE). In this case, the PPD / DADE (molar ratio) is preferably 100/0 to 85/15.
(2) 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) and pyromellitic dianhydride (PMDA), paraphenylenediamine (PPD), and 4,4 if necessary A combination comprising diaminodiphenyl ether (DADE). In this case, s-BPDA / PMDA is preferably 50/50 to 90/10. When PPD and DADE are used in combination, PPD / DADE is preferably 90/10 to 10/90, for example.
(3) A combination of pyromellitic dianhydride (PMDA), paraphenylenediamine (PPD) and 4,4-diaminodiphenyl ether (DADE). In this case, DADE / PPD is preferably 90/10 to 10/90.
(4) 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) as a main component (50 mol% or more of the total 100 mol% of tetracarboxylic dianhydride components) and paraphenylene What is obtained by using diamine (PPD) as a main component (50 mol% or more of 100 mol% of diamine components in total).

In the above (1) to (3), a part or all of 4,4-diaminodiphenyl ether (DADE) is changed to 3,4′-diaminodiphenyl ether or 2,2-bis [4- (4 -Aminophenoxy) phenyl] propane can also be substituted. In the above (1) to (4), a part or all of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is converted to 3,3 ′, 4,4′-benzophenonetetra according to the purpose. It can also be replaced by carboxylic dianhydride.

The combination of (1) is preferable because of excellent heat resistance. Furthermore, tetracarboxylic acid containing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as a main component (for example, 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more). A heat-resistant polyimide layer obtained from a dianhydride component and a diamine component containing paraphenylenediamine as a main component (for example, 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more) is used. Thus, a heat-fusible polyimide film excellent in low linear expansion coefficient, high elastic modulus, and dimensional stability can be obtained.

As an acid component capable of obtaining a heat-resistant polyimide layer, in addition to the above-mentioned acid component, other tetracarboxylic dianhydride components and / or other diamine components are used in combination as long as the desired properties are not impaired. be able to. Other tetracarboxylic dianhydride components include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4) -Dicarboxyphenyl) sulfide dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4- Dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis [( 3,4-dicarboxyphenoxy) phenyl] propane dianhydride and the like. Other diamine components include metaphenylene diamine, 2,4-toluenediamine, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfide, 3,3′- Diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 3,3 ' -Diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4-aminophenyl) propane, 1,3- Bis (4-aminophenoxy) benzene, 1,4-bis (4 Bis (aminophenoxy) benzenes such as aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 2,2-bis [4- (4 -Aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, and the like. The tetracarboxylic dianhydride component and / or diamine component used in combination can be used alone or in combination of two or more.

The thickness of the heat-sealable polyimide film is not particularly limited, but in the case of a heat-sealable polyimide film having a three-layer structure having a heat-sealable polyimide layer on both sides of the heat-resistant polyimide layer, the thickness of the heat-stable polyimide layer Is preferably 3 to 70 μm, more preferably 8 to 50 μm. The thickness of the single layer of the heat-fusible polyimide layer is preferably 0.5 to 15 μm, and more preferably 1 to 12.5 μm. The total thickness of the heat-fusible polyimide layers on both sides is preferably 1 to 30 μm, and more preferably 2 to 25 μm.

The heat-fusible polyimide film obtained in the present invention is excellent in heat resistance, particularly solder heat resistance. Moreover, the water absorption rate of the heat-fusible layer of the heat-fusible polyimide film is, for example, 0.6% or less, preferably 0.5% or less. Furthermore, the linear expansion coefficient of the heat-fusible polyimide film is, for example, 16 to 22 ppm / ° C. The elastic modulus of the heat-fusible polyimide film is, for example, 5.5 to 8 GPa. The method for measuring the water absorption rate, the linear expansion coefficient, and the elastic modulus will be described in the Examples section.

Here, the single-layer heat-fusible polyimide film composed only of the heat-fusible polyimide layer described above will be described. The single-layer heat-fusible polyimide layer is obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component. The heat-fusible polyimide contains 50 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in at least all tetracarboxylic dianhydride components, and 2,3,3 ′, 4 It may contain more than 0 and less than 50 mol% of '-biphenyltetracarboxylic dianhydride. Of the total tetracarboxylic dianhydride component, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is preferably 70 mol% or more, more preferably 80 mol% or more, more preferably 90 mol%. Including above. In addition, a polyimide metal laminate having a high peel strength, which will be described later, contains 10 to 30 mol% of 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component. From the viewpoint of obtaining. Further, the diamine component contains an amount exceeding 50 mol% of 2,2-bis [4- (4-aminophenoxy) phenyl] propane in the total diamine. The content of 2,2-bis [4- (4-aminophenoxy) phenyl] propane in the total diamine is 70 mol% or more and 100% or less from the viewpoint of obtaining a polyimide film having excellent heat resistance and low water absorption, which will be described later. preferable.

The thickness of the single-layer heat-fusible polyimide film is not particularly limited, but is 75 μm or less, preferably 8 to 50 μm, and more preferably 10 to 50 μm. In addition, about the form which is not described above, the description content of the said "multilayer heat-fusible polyimide film" is applicable as it is.

[Method for producing heat-fusible polyimide film]
Next, as an example of the method for producing the heat-fusible polyimide film of the present invention, a method for producing a heat-fusible polyimide film having a heat-fusible polyimide layer on one or both sides of the heat-resistant polyimide layer will be described.

(Manufacturing method of multilayer heat-fusible polyimide film by coating method)
The multilayer heat-fusible polyimide film is a polyimide that gives a heat-fusible polyimide layer on one or both sides of a self-supporting film obtained from a polyimide precursor solution (polyamic acid solution) (a) that gives a heat-resistant polyimide layer. It can be obtained by applying a precursor solution (polyamic acid solution) (b) and imidizing by heating and drying the resulting multilayer self-supporting film.

The self-supporting film obtained from the polyimide precursor solution (a) that gives the heat-resistant polyimide layer is substantially the same in terms of the tetracarboxylic acid component and the diamine component, or a slight excess of either component. A polyamic acid solution [polyimide precursor solution (a)] obtained by reacting in a solvent can be cast on a support and dried by heating.

On the other hand, the polyimide precursor solution (b) that gives the heat-fusible polyimide layer also has a tetracarboxylic acid component and a diamine component that are substantially equimolar, or a slight excess of either component in an organic solvent. It is obtained by reacting.

Here, the polyimide precursor solution (b) that gives the heat-fusible polyimide layer was prepared by using 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as a tetracarboxylic dianhydride component, The carboxylic dianhydride component contains 50 mol% or more, and the diamine component contains 2,2-bis [4- (4-aminophenoxy) phenyl] propane in excess of 50 mol% in the total diamine.
In addition, the polyimide precursor solution (polyamic acid solution) (a) that gives the heat-resistant polyimide layer is obtained by adding 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component. Contains 50 mol% or more.
Further, the polyimide precursor solution (b) for providing the heat-fusible polyimide layer may contain 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride. In this case, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride may be contained in the total tetracarboxylic dianhydride component in an amount of less than 50 mol%, preferably 10 to 30 mol%. Thereby, the polyimide metal laminated body with high peeling strength can be obtained.

Examples of the organic solvent for producing the polyimide precursor solution include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, Examples thereof include amides such as hexamethylsulfuramide, sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide, and sulfones such as dimethyl sulfone and diethyl sulfone. These solvents may be used alone or in combination.

The concentration of all monomers in the organic solvent when carrying out the polymerization reaction of the polyimide precursor can be appropriately selected according to the purpose of use. For example, in the polyimide precursor solutions (a) and (b), the concentration of all monomers in the organic solvent is preferably 5 to 40% by mass, more preferably 6 to 35% by mass, and 10 to 30%. It is particularly preferable that the content is% by mass.

As an example of the manufacture example of a polyimide precursor solution (a) and a polyimide precursor solution (b), for example, a tetracarboxylic acid component and a diamine component are substantially equimolar, or either component (acid component or diamine). Component) is slightly mixed and mixed, and the reaction is carried out at a reaction temperature of 100 ° C. or lower, preferably 80 ° C. or lower, more preferably 0 to 60 ° C. for about 0.2 to 60 hours to obtain a polyamic acid (polyimide precursor) solution. Obtainable.

The solution viscosity of the polyimide precursor solution (a) and the polyimide precursor solution (b) can be appropriately selected depending on the purpose (coating, casting, etc.) to be used. For example, when the polyimide precursor solution (a) and the polyimide precursor solution (b) are used for casting, the rotational viscosity measured at 30 ° C. is about 100 from the viewpoint of workability in handling the polyimide precursor solution. It is preferably ˜5000 poise, more preferably 500 to 4,000 poise, and particularly preferably about 1000 to 3,000 poise. Further, when the polyimide precursor solution (a) and the polyimide precursor solution (b) are used for coating, the rotational viscosity measured at 30 ° C. is 1 to 100 centipoise from the viewpoint of workability in handling the polyimide precursor solution. It is preferably 3 to 50 centipoise, more preferably 5 to 20 centipoise. Therefore, it is desirable to carry out the polymerization reaction to such an extent that the produced polyamic acid (polyimide precursor) exhibits the above viscosity. Moreover, said organic solvent can be added to the manufactured polyamic acid solution, and solution viscosity can also be adjusted.

The polyimide precursor solution (a) self-supporting film used as the heat-resistant polyimide layer may be, for example, a polyimide precursor solution (a) or a suitable support (for example, a metal, ceramic, plastic roll, or metal belt). ) To form a film having a uniform thickness, and then heated to 50 to 210 ° C., particularly 60 to 200 ° C. using a heat source such as hot air or infrared rays, It can be obtained by gradually removing and drying until it becomes self-supporting (for example, to the extent that it can be peeled off from the support).

In the present invention, a polyimide precursor solution (b) that gives a heat-fusible polyimide layer is applied to one side or both sides of the self-supporting film of the polyimide precursor solution (a) thus obtained. The polyimide precursor solution (b) may be applied to the self-supporting film peeled from the support, or may be applied to the self-supporting film on the support before peeling from the support.

The polyimide precursor solution (b) can be applied to the self-supporting film of the polyimide precursor solution (a), for example, gravure coating method, spin coating method, silk screen method, dip coating method, spray coating method. , Known coating methods such as bar coating, knife coating, roll coating, blade coating and die coating.

In the present invention, it is preferable to uniformly apply the polyimide precursor solution (b) to one side or both sides of the self-supporting film of the polyimide precursor solution (a). Therefore, the self-supporting film of the polyimide precursor solution (a) preferably has a surface on which the polyimide precursor solution (b) can be applied uniformly.

The self-supporting film of the polyimide precursor solution (a) preferably has a loss on heating in the range of 20 to 40% by mass, and preferably has an imidization ratio in the range of 8 to 40%. If the heating weight loss and imidization rate are within the above ranges, the mechanical properties of the self-supporting film will be sufficient, and it will be easier to cleanly apply the polyimide precursor solution (b) on the upper surface of the self-supporting film, and imidization will occur. Generation | occurrence | production of a foam, a crack, a craze, a crack, crack, etc. is not observed in the polyimide film obtained later, and the adhesive strength of a heat resistant polyimide layer and a heat-fusible polyimide layer becomes enough.

The loss on heating of the self-supporting film is a value obtained by drying the film to be measured at 400 ° C. for 30 minutes, and calculating from the weight before drying (W1) and the weight after drying (W2) by the following equation. .
Loss on heating (mass%) = {(W1-W2) / W1} × 100

Further, the imidization ratio of the self-supporting film can be calculated by measuring the IR spectrum of the self-supporting film and its fully cured product (polyimide film) by the ATR method and using the ratio of the peak area of the vibration band. . As the vibration band peak, an asymmetric stretching vibration band of an imide carbonyl group, a benzene ring skeleton stretching vibration band, or the like is used. As for imidation rate measurement, there is also a method using a Karl Fischer moisture meter described in JP-A-9-316199.

In addition, a fine inorganic or organic filler (additive) can be mix | blended with a heat resistant polyimide layer as needed. Examples of inorganic additives include particulate or flat inorganic fillers, such as particulate titanium dioxide powder, silicon dioxide (silica) powder, magnesium oxide powder, aluminum oxide (alumina) powder, and zinc oxide powder. Inorganic oxide powder such as, inorganic nitride powder such as particulate silicon nitride powder and titanium nitride powder, inorganic carbide powder such as silicon carbide powder, inorganic such as particulate calcium carbonate powder, calcium sulfate powder and barium sulfate powder Mention may be made of salt powder. Examples of the organic additive include polyimide particles and thermosetting resin particles. These additives may be used in combination of two or more. About the usage-amount and shape (size, aspect ratio) of an additive, it is preferable to select according to a use purpose. Moreover, in order to disperse these additives uniformly, a means known per se can be applied.

After the polyimide precursor solution (b) is applied to the self-supporting film of the polyimide precursor solution (a), this is then heated and imidized to obtain a multilayer heat-fusible polyimide film. The maximum heating temperature of the heat treatment for imidation is preferably 350 ° C. to 600 ° C., more preferably 380 to 520 ° C., more preferably 390 to 500 ° C., and more preferably 400 to 480 ° C.

The heat treatment for imidization is preferably performed in stages, and is first subjected to primary heat treatment at a temperature of 200 ° C. or higher and lower than 300 ° C. for 1 minute to 60 minutes, and then at a temperature of 300 ° C. or higher and lower than 350 ° C. for 1 minute. Secondary heat treatment for ˜60 minutes, and then the maximum heating temperature of 350 ° C. to 600 ° C., preferably 450 to 590 ° C., more preferably 490 to 580 ° C., more preferably 500 to 580 ° C. for 1 minute to 30 minutes. A tertiary heat treatment is desirable. This heat treatment can be performed using a known apparatus such as a hot air furnace or an infrared heating furnace.

Further, this heat treatment is preferably performed by fixing the self-supporting film of the polyimide precursor solution (a) coated with the polyimide precursor solution (b) with a pin tenter, a clip or the like.

The polyimide precursor solution (b) and / or the polyimide precursor solution (a) is used for the purpose of limiting the gelation of the polyamic acid (polyimide precursor). Phenyl and the like can be added in the range of 0.01 to 1% with respect to the solid content (polymer) concentration during polyamic acid polymerization.

From the viewpoint of the film surface state and productivity, it is preferable to add a phosphate ester or a salt of a tertiary amine and a phosphate ester to the polyamic acid solution. These addition amounts are preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the polyimide or polymer. Specific examples of the phosphate ester include distearyl phosphate ester and monostearyl phosphate ester. Examples of the salt of tertiary amine and phosphate ester include monostearyl phosphate ester triethanolamine salt. For imidization in the present invention, either thermal imidization (thermal imidization) or chemical imidization (chemical imidization) can be applied. Among these, thermal imidization can be suitably applied.

Further, a basic organic compound can be added to the polyimide precursor solution (b) and / or the polyimide precursor solution (a) for the purpose of promoting imidization. For example, imidazole, 2-methylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, benzimidazole, isoquinoline, substituted pyridine and the like are 0.05 to 10% by mass with respect to the polyamic acid (polyimide precursor), preferably It can be used in a proportion of 0.05 to 5% by mass, particularly preferably 0.1 to 2% by mass. These can be used to avoid insufficient imidization to form polyimide films at relatively low temperatures.

(Method for producing heat-fusible polyimide film by coextrusion-casting film formation method)
The multilayer polyimide film of the present invention is obtained by a coextrusion-casting film forming method (also simply referred to as a coextrusion method), a heat-resistant polyimide layer dope solution (also referred to as a polyamic acid solution or a polyimide precursor solution), It can also be produced by a method of obtaining a multilayer polyimide film by laminating, drying and imidizing with a dope solution of a heat-fusible polyimide layer. As this coextrusion method, for example, a method described in JP-A-3-180343 (Japanese Patent Publication No. 7-102661) can be used.
More specifically, this co-extrusion method first uses an extrusion molding machine having two or more layers of extrusion dies, and the dope solution of the heat-resistant polyimide layer and the heat-sealable polyimide from the discharge port of the dies. A layered dope solution is cast on a support to form a laminated thin film. Then, the thin film on the support is dried to form a multilayer self-supporting film, then the multilayer self-supporting film is peeled off from the support, and finally the multilayer self-supporting film is heat-treated. It is to do. In this embodiment, the dope solution in contact with the support may be either a dope solution that provides a heat-resistant polyimide layer or a dope solution that provides a heat-fusible polyimide layer. At this time, the drying is preferably performed by drying the thin film at a temperature exceeding 135 ° C., specifically 140 ° C. or higher, preferably 145 ° C. or higher to form a self-supporting film. Thereby, the peeling strength of the polyimide metal laminated body mentioned later improves.

As the two-layer extrusion die, for example, a dope solution supply port is provided, and a dope solution passage is formed from each supply port toward each manifold, and a flow path at the bottom of the manifold is formed. A structure in which the dope solution passage (lip portion) joins at the junction and communicates with the slit-like discharge port, and the dope solution is discharged from the discharge port onto the support in the form of a thin film. What is (multi-manifold type two-layer die) can be mentioned. The gap between the lip portions can be adjusted by a lip adjustment bolt.
Further, at the bottom of each manifold (location close to the merging point), the distance between the gaps of the flow path is adjusted by each choke bar. Each of the manifolds preferably has a hanger coat type shape. In addition, the double-layer extrusion die has respective dope supply ports on the left and right sides of the upper portion of the die, and the dope solution passages are immediately joined at the junction where the partition plate is provided. A dope solution flow path communicates from the junction to the manifold, and a dope solution passage (lip portion) at the bottom of the manifold communicates with the slit-like discharge port. A structure (feed block type double-layer die or single manifold type double-layer die) in which the dope solution is discharged on the support in the form of a groove film from the discharge port may be used. The form of drying conditions and heating conditions after the operation of continuously extruding onto the support in the coextrusion-casting film forming method is as described in “Method for producing multilayer heat-fusible polyimide film by coating method”. The description can be applied as it is.

In addition to the above two-layer extrusion, a multilayer extrusion polyimide film can be produced by a molding method similar to the two-layer extrusion molding by using three or more dies for extrusion molding. That is, when a heat-resistant polyimide layer dope and a heat-fusible polyimide layer dope are used, a two-layer heat-fusible polyimide film can be obtained. In addition, in the case of a layer configuration of a heat-fusible polyimide layer dope liquid-a heat-resistant polyimide layer dope liquid-a heat-fusible polyimide layer dope liquid, a three-layer heat-fusible polyimide film is obtained. You can also.

(Other variations of manufacturing method of heat-fusible polyimide film)
In addition, the multilayer polyimide film of the present invention is obtained by applying a polyamic acid solution of a heat-fusible polyimide to a heat-resistant polyimide film, heating and drying to imidize the heat-fusible layer. You can also. As the heat resistant polyimide film, a film obtained by forming the heat resistant polyimide film composition by a known method or a commercially available polyimide film can be used. Examples of commercially available heat-resistant polyimide films include Upilex (registered trademark) manufactured by Ube Industries, Kapton EN (registered trademark) manufactured by Toray DuPont, Apical NPI (registered trademark) manufactured by Kaneka Corporation, and the like. .
The amic acid solution of the heat-fusible polyimide film to be applied and the drying conditions can be performed in the same manner as in the application to the self-supporting film.
Moreover, in order to raise the adhesive strength of a heat resistant polyimide film and a heat-fusible polyimide film, it is desirable to surface-treat a heat resistant polyimide film before coating. Examples of the surface treatment method include corona treatment, plasma treatment, alkali treatment, etching treatment, coupling agent treatment, or a combination thereof.

Next, an example of a method for producing a single-layer heat-fusible polyimide film will be described. For the forms not described below, the description in the above-mentioned “Method for producing multilayer heat-fusible polyimide film by coating method” and “Method for producing heat-fusible polyimide film by coextrusion-casting film forming method” is provided. The content can be applied as it is.

The single layer heat-fusible polyimide film contains 50 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in at least all tetracarboxylic dianhydride components, A tetracarboxylic dianhydride component containing more than 0 and less than 50 mol% of 3 ′, 4′-biphenyltetracarboxylic dianhydride, and 2,2-bis [4- (4-aminophenoxy) phenyl in all diamines A polyamic acid solution containing a diamine component containing more than 50 mol% of propane is cast or applied onto a carrier film, dried, and then heat-treated to obtain a heat-fusible polyimide film with a carrier film. Can be obtained as

The polyamic acid solution is cast or coated on a carrier film and dried. The drying temperature is, for example, 80 to 200 ° C., preferably 100 to 200 ° C.

A polyimide film can be suitably used as the carrier film. As the carrier film, a commercially available polyimide film can be used. For example, Upyorex (registered trademark) manufactured by Ube Industries, Kapton EN (registered trademark) manufactured by Toray DuPont, Apical manufactured by Kaneka Corporation NPI (registered trademark) and the like can be mentioned. Among these, from the viewpoints of peelability of the heat-fusible polyimide film from the carrier film and film rigidity, Upilex (25S, 50S, 75S, 125S) manufactured by Ube Industries is preferably used. The thickness of the polyimide film as the carrier film is preferably 50 μm or more, more preferably 75 to 125 μm. By using such a carrier film, it is possible to obtain a single-layer heat-fusible polyimide film having excellent adhesion to metal on both sides (high peel strength).

A polyimide film as a carrier film is obtained by polymerizing a tetracarboxylic dianhydride component and a diamine component to obtain a polyamic acid solution, casting or coating the polyamic acid solution on a support, and drying it. After obtaining the support film, the self-support film is heated to imidize. Here, of both surfaces of the polyimide film as the carrier film, the surface that was in contact with the support when the polyamic acid solution was cast or applied onto the support was referred to as the B surface, and was not in contact with the support (air Side) surface.

The method for casting or coating is not particularly limited. For example, gravure coating, spin coating, silk screen, dip coating, spray coating, bar coating, knife coating, roll coating, blade coating And a method such as a die coating method.

The surface of the carrier film on which the polyamic acid solution is cast or applied may be either the A surface or the B surface, but it is preferable to cast or apply the polyamic acid solution on the B surface of the carrier film. Thereby, the adhesiveness with the metal of a heat-fusible polyimide film improves, and the peeling strength of the polyimide metal laminated body obtained by bonding together with a metal becomes high. In particular, when the thickness of the carrier film is 75 μm or more, preferably 75 to 125 μm, it is preferable to cast or apply the polyamic acid solution to the B surface of the carrier film.

After drying the polyamic acid solution, the dried product (with a carrier film) is then heat-treated. Thereby, while remaining solvent is fully removed, imidation is advanced. The temperature of the heat treatment is higher than the above drying temperature, preferably 100 to 400 ° C., more preferably 300 to 400 ° C. The heat treatment time is, for example, 1 to 100 minutes.

The heat treatment is performed continuously or intermittently. When the heat treatment is continuously performed, it is preferable that at least a pair of both end edges of the dried product is fixed in a movable fixing device or the like. The heat treatment can be performed using an apparatus such as a hot air furnace or an infrared heating furnace. As a fixing device for the dried product (solidified film), for example, a belt-like or chain-like one provided with a large number of pins or gripping tools at equal intervals, the length of the solidified film supplied continuously or intermittently is used. A device that can be installed in a pair along both side edges in the direction and can fix the film while moving the film continuously or intermittently with the movement of the film is suitable. In addition, the solidified film fixing device can expand and contract the film being heat-treated in the width direction or the longitudinal direction at an appropriate elongation or contraction rate (particularly preferably an expansion ratio of about 0.5 to 5%). It may be a device.

Incidentally, the heat-welding polyimide film, again, preferably 400 gf / mm ² or less, particularly preferably under 300 gf / mm ² or lower tension or under no tension, the temperature of 100 ~ 400 ° C., preferably 0. By heat-treating for 1 to 30 minutes, a heat-fusible polyimide film having particularly excellent dimensional stability can be obtained.

The produced heat-fusible polyimide film with a long carrier film can be wound into a roll.

Finally, the carrier film can be peeled from the heat-fusible polyimide film with a carrier film to obtain a single-layer heat-fusible polyimide film.

[Polyimide metal laminate]
Next, the polyimide metal laminate of the present invention will be described. The polyimide metal laminate of the present invention is formed by laminating a metal layer on the heat-fusible polyimide layer of the heat-fusible polyimide film of the present invention. A metal layer may be laminated on both surfaces of the heat-fusible polyimide film, or a metal layer may be laminated only on one surface of the heat-fusible polyimide film. The polyimide metal laminate of the present invention is laminated on one or both sides of the heat-fusible polyimide film having the heat-fusible polyimide layer on one or both sides of the outermost layer and the heat-fusible polyimide layer. You may do it.
That is, the polyimide metal laminate of the present invention is obtained by laminating a metal layer on the heat-fusible polyimide layer of the heat-fusible polyimide film having the heat-fusible polyimide layer on at least one or both surfaces of the outermost layer. Formed. When the metal layer is formed on one side of the heat-fusible polyimide film, the heat-fusible polyimide film having the heat-fusible polyimide layer on one side or both sides of the outermost layer of the heat-fusible polyimide film is used. . Moreover, when forming a metal layer on both surfaces, the said heat-fusible polyimide film which has the said heat-fusible polyimide layer on both surfaces of the said heat-fusible polyimide film is used.

When a metal layer is laminated on a single-layer heat-sealable polyimide film, the surface of the heat-sealable polyimide film on which the metal layer is laminated is a carrier during the production of the single-layer heat-sealable polyimide film described above. It is preferable that the surface has no film. When a polyimide metal laminate is obtained using a single layer heat-fusible polyimide film, the metal layer is laminated on one side or both sides of the heat-fusible polyimide film.

The metal layer is preferably a metal foil. As the metal foil, various metal foils such as copper, aluminum, gold, or an alloy of these alloys can be used. Among these, copper foil is preferably used. Specific examples of the copper foil include rolled copper foil and electrolytic copper foil.

When laminating metal layers on both sides of the heat-fusible polyimide film, the same or different metals can be used.

The thickness of the metal foil is not particularly limited, but is preferably 2 to 35 μm, and particularly preferably 5 to 18 μm. As the metal foil having a thickness of 5 μm or less, a metal foil with a carrier, for example, a copper foil with an aluminum foil carrier can be used.

In the present invention, the heat-fusible polyimide film and the metal layer are thermocompression-bonded by superimposing a metal layer (metal foil or the like) on both sides of the heat-fusible polyimide film having the heat-fusible polyimide layer formed on both sides. Thereby, the polyimide metal laminated body by which the metal layer was laminated | stacked on both surfaces of the heat-fusible polyimide film can be obtained. A heat-fusible polyimide film in which a metal layer (such as a metal foil) is stacked on the heat-fusible polyimide layer on one side of the heat-fusible polyimide film having a heat-fusible polyimide layer formed on at least one side; By thermocompression bonding with the metal layer, a polyimide metal laminate in which the metal layer is laminated on one surface of the heat-fusible polyimide film can be obtained.

The heat-fusible polyimide film and the metal foil are heated at least by a pair of pressure members so that the temperature of the pressure part is 30 ° C. higher than the glass transition temperature of the heat-fusible polyimide and 420 ° C. or lower. It is preferable to perform thermocompression bonding continuously.

Examples of the pressure member include a pair of pressure-bonding metal rolls (the pressure-bonding portion may be made of metal or ceramic sprayed metal), a double belt press, and a hot press, and particularly capable of thermocompression bonding and cooling under pressure. Of these, a hydraulic double belt press is particularly preferred. Also, a polyimide metal laminate can be easily obtained by roll lamination using a pair of crimped metal rolls.

In the present invention, the pressure member, for example, a metal roll or preferably a double belt press is used, and the heat-fusible polyimide film, the metal foil, and the reinforcing material are superposed and continuously heated. A long polyimide metal laminate can be produced by pressure bonding.

Further, the heat-fusible polyimide film and the metal foil are used in a roll-wound state, and are continuously supplied to the pressure members, respectively, and are particularly suitable when the polyimide metal laminate is obtained in a roll-wound state. .

In the polyimide metal laminate of the present invention, the heat-fusible polyimide film and the metal foil are firmly laminated. According to the present invention, for example, the peel strength measured by the method of JIS C6471 is 0.5 N / mm or more, preferably 0.7 N / mm or more, more preferably 0.9 N / mm or more, and further preferably 1.3 N. A polyimide metal laminate that is at least / mm can be obtained.
Of the three layers of heat-fusible polyimide films in which the heat-fusible polyimide layer is laminated on both sides of the heat-resistant polyimide layer, in the polyimide metal laminate in which the metal layer is laminated on the heat-fusible polyimide layer, The peeling state (peeling mode) includes a case where peeling occurs at the interface between the heat-resistant polyimide layer and the heat-fusible polyimide film, and a case where peeling occurs at the interface between the heat-fusible polyimide layer and the metal layer. Therefore, the measured peel strength is the peel strength of the surface with weaker adhesive force.
In the present invention, the peel strength measurement method is as follows. First, a copper foil (3EC-VLP, manufactured by Mitsui Kinzoku Co., Ltd., 3μ-VLP, thickness 18 μm) is superimposed on the heat-fusible polyimide layer of the heat-fusible polyimide film, and 30 ° C. or more from the glass transition temperature of the heat-fusible polyimide. A polyimide metal laminate in which a copper foil is laminated on a heat-fusible polyimide film is obtained by thermocompression bonding at a high temperature of 420 ° C. or less at a residual heat of 5 minutes, a press pressure of 3 MPa, and a press time of 1 minute. Next, the peel strength of this polyimide metal laminate is measured by the method of JIS C6471. In addition, it does not specifically limit about the kind of copper foil used for the measurement of peeling strength. The glass transition temperature of the heat-fusible polyimide varies depending on the types of the tetracarboxylic dianhydride component and the diamine component that constitute the heat-fusible polyimide. The said thermocompression bonding temperature is suitably set according to the glass transition temperature of the heat-fusible polyimide used.

The heat-fusible polyimide film of the present invention can be used as an adhesive sheet or an adhesive tape.

The polyimide metal laminate of the present invention has good moldability and can be directly subjected to drilling, bending, drawing, metal wiring formation, and the like. Moreover, the heat-fusible polyimide film of this invention can be used for the thermocompression bonding of the electronic circuit on wiring. The heat-fusible polyimide film and the polyimide metal laminate of the present invention can be used as materials for electronic parts and electronic devices such as a printed wiring board, a flexible printed circuit board, and a TAB tape. Further, the heat-fusible polyimide film of the present invention includes a tab lead sealing material such as a lithium ion battery, a polymer battery, and an electric double layer capacitor using an aluminum laminate film as an outer bag, a cover lay of a flexible printed circuit board, and a ceramic package. It can be suitably used as an adhesive sheet that requires reliability at high temperatures, such as a bonding material between a cap and a cap.

In addition, in the above, although the metal layer was mentioned as an adherend laminated | stacked on a heat-fusible polyimide film, it is not limited to this. Examples of the adherend other than metal include ceramic, glass, and polyimide film.

Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited by the following examples.

[Measurement method for each evaluation]
1. Measurement of glass transition temperature (Tg) of single-layer heat-fusible polyimide film Using the obtained film, Rheometrics Solid Analyzer II manufactured by Rheometric Scientific, Inc., dynamic viscoelasticity measurement (temperature increase rate: 10 ° C / min) The frequency was evaluated by the peak temperature of tan δ.

2. Measurement of water absorption rate of single layer heat-fusible polyimide film Measured weight increase from absolute dry weight of sample absorbed in water at 23 ° C for 24 hours or more, [(absorbed weight)-(absolute dry weight)] / (Absolute dry weight).

3. Measurement of the coefficient of linear expansion (CTE) of a three-layer heat-fusible polyimide film A sample sampled to a length of 15 mm / width of 3 mm was measured in a tensile mode, a load of 4 gf, and a heating rate of 20 ° C / min. Calculated from a 200 ° C. TMA curve.

4). Measurement of peel strength of polyimide metal laminate The peel strength of the polyimide metal laminate was measured by the method of JIS C6471.

5. Evaluation of solder heat resistance of polyimide metal laminate A resist is printed on one side of the obtained polyimide metal laminate and immersed in an etching solution at 30 ° C. for 20 to 30 minutes to obtain a laminate in which the metal layer on one side is etched. It was. The obtained laminate was dried at 80 ° C. for 30 minutes, and the sample conditioned for 24 hours or more in an environment of 23 ° C.-60% RH was floated in a solder bath at various temperatures for 10 seconds. It was confirmed. The maximum temperature at which foaming was not confirmed was defined as the solder heat resistance temperature.

6). Evaluation of dimensional change of polyimide metal laminate A resist was printed on one side of the obtained polyimide metal laminate and immersed in an etching solution at 30 ° C. for 20 to 30 minutes to obtain a laminate in which the metal layer on one side was etched. . The obtained laminate was cut into a 86 mmφ circle, dried at 80 ° C. for 30 minutes, and conditioned for 24 hours or more in an environment of 23 ° C.-60% RH. The dimensional change was estimated in the state of warping of the sample. The circle end warp amount was evaluated as “◯” when the warp amount was within 5 mm, “X” when the warp amount could not be measured (end portion was warped by 90 ° or more), and “Δ” between them.

[Synthesis of polyamic acid solution A giving heat-resistant polyimide layer (core layer)]
Dimethylacetamide (DMAc) is added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and paraphenylenediamine (PPD) and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) are added. ) To obtain a polyamic acid solution A having a monomer concentration of 18% by weight and a solution viscosity at 25 ° C. of 1500 poise.

[Synthesis of polyamic acid solution B giving heat-resistant polyimide layer (core layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and PPD as a diamine component, 4,4-diaminodiphenyl ether (DADE) and 2,2-bis [4- (4-aminophenoxy) phenyl] Propane (BAPP), s-BPDA as tetracarboxylic dianhydride component and pyromellitic dianhydride (PMDA) are supplied, the tetracarboxylic dianhydride component and the diamine component are reacted, and the monomer concentration 18 wt% of polyamic acid solution B was obtained. The molar ratio of PPD, DADE and BAPP was 50:30:20. The molar ratio of s-BPDA to PMDA was 20:80.

[Synthesis of polyamic acid solution C giving heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP was further added. Subsequently, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (a-BPDA) and s-BPDA were added, the monomer concentration was 18 wt%, and the solution viscosity at 25 ° C. was 800 poise. An acid solution C was obtained. The molar ratio of a-BPDA and s-BPDA was 10:90.

[Synthesis of polyamic acid solution C ′ to give heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP was further added. Subsequently, a-BPDA and s-BPDA were added to obtain a polyamic acid solution C ′ having a monomer concentration of 18% by weight. The molar ratio of a-BPDA and s-BPDA was 30:70.

[Synthesis of polyamic acid solution D giving heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and 1,3-bis (4-aminophenoxy) benzene (TPE-R) were further added. Subsequently, s-BPDA was added to obtain a polyamic acid solution D having a monomer concentration of 18% by weight. The molar ratio of BAPP and TPE-R was 70:30.

[Synthesis of polyamic acid solution D ′ providing a heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and 1,3-bis (4-aminophenoxy) benzene (TPE-R) were further added. Subsequently, a-BPDA and s-BPDA were added to obtain a polyamic acid solution D ′ having a monomer concentration of 18% by weight. The molar ratio of a-BPDA and s-BPDA was 10:90. The molar ratio of BAPP and TPE-R was 70:30.

[Synthesis of polyamic acid solution E to give heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and s-BPDA were further added to obtain a polyamic acid solution E having a monomer concentration of 18% by weight.

[Synthesis of polyamic acid solution F that gives a heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and TPE-R were further added. Subsequently, a-BPDA and s-BPDA were added to obtain a polyamic acid solution F having a monomer concentration of 18% by weight. The molar ratio of a-BPDA and s-BPDA was 10:90. The molar ratio of BAPP and TPE-R was 50:50.

[Synthesis of polyamic acid solution G to give heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and TPE-R and 1,4-bis (4-aminophenoxy) benzene (TPE-Q) were further added. Subsequently, a-BPDA and s-BPDA were added to obtain a polyamic acid solution G having a monomer concentration of 18% by weight. The molar ratio of a-BPDA and s-BPDA was 30:70. The molar ratio of TPE-R to TPE-Q was 30:70 (BAPP was 0 mol%).

[Synthesis of polyamic acid solution H that gives heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and PPD were further added. Subsequently, a-BPDA and s-BPDA were added to obtain a polyamic acid solution H having a monomer concentration of 18% by mass. The molar ratio of a-BPDA and s-BPDA was 20:80. The molar ratio of BAPP and PPD was 70:30.

[Synthesis of polyamic acid solution I giving heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and PPD were further added. Subsequently, s-BPDA was added to obtain a polyamic acid solution I having a monomer concentration of 18% by mass. The molar ratio of BAPP and PPD was 90:10.

[Synthesis of polyamic acid solution J that gives a heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and PPD were further added. Subsequently, s-BPDA was added to obtain a polyamic acid solution J having a monomer concentration of 18% by mass. The molar ratio of BAPP and PPD was 80:20.

[Synthesis of polyamic acid solution K that gives heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and PPD were further added. Subsequently, s-BPDA was added to obtain a polyamic acid solution K having a monomer concentration of 18% by mass. The molar ratio of BAPP and PPD was 75:25.

[Synthesis of polyamic acid solution L that gives a heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and PPD were further added. Subsequently, s-BPDA was added to obtain a polyamic acid solution L having a monomer concentration of 18% by mass. The molar ratio of BAPP and PPD was 70:30.

[Synthesis of polyamic acid solution M that gives heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP and PPD were further added. Subsequently, s-BPDA was added to obtain a polyamic acid solution M having a monomer concentration of 18% by mass. The molar ratio of BAPP and PPD was 65:35.

[Synthesis of polyamic acid solution N to give heat-fusible polyimide layer (fusion layer)]
DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen introduction tube, and BAPP was further added. Subsequently, s-BPDA and PMDA were added to obtain a polyamic acid solution N having a monomer concentration of 18% by mass. The molar ratio of s-BPDA to PMDA was 10:90.

[Reference Example 1]
The polyamic acid solution E was cast into a glass plate using a coater and dried at 120 ° C. for 12 minutes in a drying furnace to obtain a self-supporting film. The obtained self-supporting film was affixed to a four-way tenter and heated at 150 ° C., 200 ° C., 250 ° C., and 340 ° C. for 2 minutes each to obtain a single layer heat-fusible polyimide film having a thickness of 20 μm. It was. Table 1 shows the glass transition temperature and water absorption of the heat-fusible polyimide film.

[Reference Examples 2 to 7]
A single-layer heat-fusible polyimide film was obtained in the same manner as in Reference Example 1 except that the polyamic acid solution was changed as shown in Table 1. Table 1 shows the glass transition temperature and water absorption of the heat-fusible polyimide film. From the results of Table 1, it has been clarified that when the BAPP in the diamine component exceeds 50 mol%, particularly 70 mol% or more, a heat-fusible polyimide film having a low water absorption rate can be obtained.

(Multilayer heat-fusible polyimide film and polyimide metal laminate)
[Example 1]
From the three-layer extrusion die, a polyamic acid solution E (thermal fusion layer) -polyamic acid solution A (core layer) -polyamic acid solution E (thermal fusion layer) is formed on the upper surface of a smooth metal support. Thus, the polyamic acid solution A and the polyamic acid solution E were extruded and cast. The thin film casting was continuously dried with hot air at 145 ° C. to form a self-supporting film. After peeling the self-supporting film from the support, it is gradually heated from 200 ° C. to 460 ° C. in a heating furnace (maximum heating temperature is 460 ° C.), the solvent is removed and imidized, and a thickness of 25 μm (two heats) A multilayer heat-fusible polyimide film having a three-layer structure in which the thickness of the fusion layer was 4.5 μm and the thickness of the core layer was 16 μm was obtained. Table 2 shows the linear expansion coefficient and elastic modulus of the heat-fusible polyimide film.
Next, a copper foil (3EC-VLP, manufactured by Mitsui Kinzoku Co., Ltd., 3 μm thickness) is superimposed on both sides of the obtained heat-fusible polyimide film, and the temperature is 300 ° C., the remaining heat is 5 minutes, the pressing pressure is 3 MPa, and the pressing time is 1. The polyimide metal laminated body by which the copper foil was laminated | stacked on both surfaces of the heat-fusible polyimide film was obtained by carrying out the thermocompression bonding in minutes. Each evaluation of the peeling strength of this polyimide metal laminated body and solder heat resistance was performed. The results are shown in Table 2.

[Examples 2 to 12, Comparative Examples 1 to 5]
A heat-fusible polyimide film was obtained in the same manner as in Example 1 except that the type of polyamic acid solution and the drying temperature of the cast were changed as shown in Table 2. Table 2 shows the linear expansion coefficient and elastic modulus of the heat-fusible polyimide film. A polyimide metal laminate was obtained in the same manner as in Example 1. Each evaluation of the peeling strength of this polyimide metal laminated body and solder heat resistance was performed. The results are shown in Table 2.

In all the examples and comparative examples in Table 2, the peel strength was measured at the interface between the heat-resistant polyimide layer and the heat-fusible polyimide layer. The dimensional stability of the polyimide metal laminates of Examples 10 to 12 was “◯”, and that of Comparative Example 3 was “Δ”.

The following are the main findings from the above results.
(1) When the drying temperature of the self-supporting film is 140 ° C. or higher, the peel strength of the polyimide metal laminate (interfacial strength between the heat-resistant polyimide layer and the heat-fusible polyimide layer) is improved.
(2) When the BAPP in the diamine component exceeds 50 mol%, preferably 65 mol% or more, particularly 70 mol% or more, the heat resistance of the polyimide metal laminate is excellent.
(3) If the core layer contains less s-BPDA as the tetracarboxylic dianhydride component, there is no problem in solder heat resistance, but the value of the linear expansion coefficient of the heat-fusible polyimide film increases, and the elastic modulus There was a tendency that the dimensional stability of the polyimide metal laminate decreased. More preferably, the core layer contains 50 mol% or more of s-BPDA as a tetracarboxylic dianhydride component.
(4) For the heat fusion layer, when BAPP and PPD are used in combination as the diamine component, and the amount of PPD is 25 mol% or more in the total diamine component, the peel strength and solder heat resistance of the polyimide metal laminate are Even better.
(5) When a-BPDA in the tetracarboxylic dianhydride component is used for the heat-sealing layer, the peel strength of the polyimide metal laminate is improved.

According to the present invention, a polyimide film having excellent heat resistance and excellent adhesion to the metal layer can be obtained. Moreover, it is excellent in heat resistance and can obtain the laminated body (polyimide metal laminated body) with high peeling strength of a polyimide film and a metal layer.

Claims

A multilayer heat-fusible polyimide film comprising a heat-fusible polyimide layer and a heat-resistant polyimide layer laminated in contact with the heat-fusible polyimide layer,
The heat-fusible polyimide layer is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the heat-fusible polyimide layer is a total tetracarboxylic dianhydride component. Among them, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is contained in an amount of 50 mol% or more, and the diamine component of the heat-fusible polyimide layer is 2,2-bis [4 -(4-aminophenoxy) phenyl] propane in excess of 50 mol%,
The heat-resistant polyimide layer is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the heat-resistant polyimide layer is the total tetracarboxylic dianhydride component, Containing 50 mol% or more of 3 ′, 4,4′-biphenyltetracarboxylic dianhydride,
A 18 μm copper foil is superposed on the heat-fusible polyimide layer of the heat-fusible polyimide film, and is higher by 30 ° C. than the glass transition temperature of the heat-fusible polyimide constituting the heat-fusible polyimide layer, and 420 ° C. The polyimide metal laminate obtained by thermocompression bonding with a press pressure of 3 MPa and a press time of 1 minute in the following temperature range has a peel strength measured by the method of JIS C6471 of 0.5 N / mm or more. Heat-sealable polyimide film.
2. The heat-fusible polyimide according to claim 1, wherein the diamine component of the heat-fusible polyimide layer contains 70 mol% or more of 2,2-bis [4- (4-aminophenoxy) phenyl] propane in the total diamine. the film.
The heat-fusible polyimide film according to claim 1 or 2, wherein the diamine component of the heat-fusible polyimide layer contains 25 mol% or more of paraphenylenediamine in all diamines.
The tetracarboxylic dianhydride component of the heat-fusible polyimide layer is 50 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component. The heat-fusible polyimide film according to any one of claims 1 to 3, further comprising more than 0 and less than 50 mol% of 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride.
The tetracarboxylic dianhydride component of the heat-fusible polyimide layer is 50 mol% or more of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride in the total tetracarboxylic dianhydride component. The heat-fusible polyimide film according to claim 4, further comprising 10 to 30 mol% of 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride.
The heat-fusible polyimide film according to any one of claims 1 to 5, wherein the diamine component of the heat-resistant polyimide layer contains 50 mol% or more of paraphenylenediamine in all diamines.
A thin film formed by casting a polyimide precursor solution (a) that gives a heat-resistant polyimide layer and a polyimide precursor solution (b) that gives a heat-fusible polyimide layer from an extrusion die onto a support. Forming a body, drying the thin-film body at a temperature of 140 ° C. or more to form a self-supporting film, peeling the self-supporting film from the support, and heating the peeled self-supporting film A method for producing a fusible polyimide film,
The polyimide precursor solution (a) is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the polyimide precursor solution (a) is all tetracarboxylic dianhydride. In the product component, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is contained at 50 mol% or more
The polyimide precursor solution (b) is obtained from a tetracarboxylic dianhydride component and a diamine component, and the tetracarboxylic dianhydride component of the polyimide precursor solution (b) is all tetracarboxylic dianhydride. In the physical component, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is contained in an amount of 50 mol% or more, and the diamine component of the polyimide precursor solution (b) is 2,2- A method for producing a heat-fusible polyimide film, comprising more than 50 mol% of bis [4- (4-aminophenoxy) phenyl] propane.
The method for producing a heat-fusible polyimide film according to claim 7, wherein the thin film-like body is dried at a temperature of 145 ° C or higher.
A polyimide metal laminate obtained by laminating a metal layer in contact with the heat-fusible polyimide layer of the heat-fusible polyimide film according to any one of claims 1 to 6.