JP4379609B2 - Method for producing flexible metal foil polyimide laminate - Google Patents

Description

  The present invention relates to a method for producing a flexible metal foil polyimide laminate that is used for electronic components such as printed boards and that is particularly excellent in flexibility.

  Conventionally, a polyimide substrate resin solution is directly applied onto a conductor, dried, and cured to produce a flexible substrate. JP-A-61-275325: Patent Document 2, JP-A-62-212140: Patent Document 3, JP-A-7-57540: Patent Document 4). In addition, a method of applying a polyimide precursor resin solution on a conductor in several times is also disclosed in Japanese Patent Laid-Open Publication No. 2-180682: Patent Document 5, Japanese Patent Laid-Open No. 2-180679: Patent Document 6. JP-A-1-245586: Patent Document 7 and JP-A-2-12297: Patent Document 8).

  However, the method of applying the polyimide precursor resin solution on the conductor has no so-called “strain” unless the final polyimide layer thickness of the flexible substrate is 20 μm or more. Since it is necessary to apply the polyimide precursor resin thickly so that the layer becomes 20 μm or more and cure on the conductor, it is difficult to apply the polyimide precursor resin with a uniform thickness, which often causes uneven thickness. It was happening to be a good product. This means that when the coating is performed in several times, the thickness unevenness becomes extremely apparent as the number of times of coating is increased.

  Therefore, a method of bonding after forming a thermoplastic polyimide on a conductor is disclosed in Patent Publications (for example, Japanese Patent Application Laid-Open No. 1-224441: Patent Document 9, Japanese Patent Application Laid-Open No. 6-190967: Patent Document 10). Has been. According to this method, since the thermoplastic polyimide layer is pressure-bonded, the thickness of the polyimide layer as a whole is known to be uniform. In particular, as disclosed in JP-A-6-190967, a polyimide or polyamic acid solution is applied, dried and cured to produce a thermoplastic polyimide / metal foil laminate, and a polyimide film on the thermoplastic polyimide side. By heating and press-bonding, the thermoplastic polyimide is melted by heating and the thickness is corrected. Therefore, the polyimide layer as a whole after being bonded to the polyimide film can have a uniform thickness.

  However, in this method, it is essential to heat and pressure-bond the cured polyimide, so that a special apparatus that can be pressure-bonded while heating at a temperature equal to or higher than the glass transition point (Tg) of the polyimide is required, which is not economical.

JP 59-232455 A JP-A 61-275325 JP-A-62-212140 JP-A-7-57540 Japanese Patent Laid-Open No. 2-180682 JP-A-2-180679 JP-A-1-245586 Japanese Patent Laid-Open No. 2-122697 JP-A-1-2444841 JP-A-6-190967

  The present invention has been made in view of the above circumstances, and is a flexible metal foil having good flexibility that fully utilizes the characteristics of a heat-resistant polyimide resin film having excellent heat resistance, chemical resistance, flame retardancy, electrical characteristics, and the like. It aims at providing the manufacturing method of a polyimide laminated board.

As a result of intensive investigations to achieve the above object, the present inventor has laminated a metal foil and a polyimide film with a heat roll press through a heat resistant adhesive, and then left the adhesive layer by heat treatment. Solvent is removed and heat cured to produce a flexible metal foil polyimide laminate. In this case, the thickness of the polyimide film is 30 μm or less, and the gas permeation amount of dimethylacetamide at 5 torr and 200 ° C. is 0.1 kg / Heat-resistant polyimide by using a material having a m ² · hr or more, further laminating with a heated roll press at a temperature of 150 ° C. or less, and then performing heat treatment and thermosetting under a reduced pressure of 10 Pa or less of absolute pressure. It is possible to produce flexible metal foil polyimide laminates with good flexibility that fully utilize the characteristics of resin films. The headline and the present invention were made.

Therefore, in the present invention, after laminating a metal foil coated with a heat-resistant adhesive and a polyimide film with a heated roll press, the residual solvent of the adhesive layer is removed by heat treatment, followed by thermosetting and flexible metal foil polyimide lamination. A method for producing a plate, as a heat-resistant adhesive, using a polyamic acid having a solvent content of 3 to 50% by mass and an imidization rate of less than 5% at the time of lamination, and having a thickness of 30 μm or less as a polyimide film, In addition, the gas permeation amount of dimethylacetamide at 5 torr and 200 ° C. is 0.1 kg / m ² · hr or more, laminated at a temperature of 150 ° C. or less by a heated roll press, and then reduced in absolute pressure to 10 Pa or less. Provided is a method for producing a flexible metal foil polyimide laminate, characterized by performing heat treatment and thermosetting under .

  According to the method of the present invention, it is possible to produce an all-polyimide flexible metal foil polyimide laminate having good bending properties.

As a polyimide film used for forming the flexible metal foil polyimide laminate of the present invention, if the thickness is 30 μm or less, and the gas permeation amount of dimethylacetamide at 5 torr and 200 ° C. is 0.1 kg / m ² · hr or more, Any polyimide film conventionally used for this type of laminated board may be used, a diamine compound represented by the following general formula (I) and a tetracarboxylic dianhydride represented by the following general formula (II): A polyimide resin film represented by the following general formula (III) obtained from the product can be used, and a commercially available product may be used. As a commercial item,
Product name: Apical manufactured by Apex Toray DuPont Co., Ltd. Product name: Kapton Ube Industries, Ltd. Product name: Upilex can be used.

H ₂ N—R ¹ —NH ₂ (I)
(In the formula, R ¹ is an aliphatic group, a cyclic aliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or a non-condensed cyclic aromatic group in which aromatics are connected directly or by a bridging member. A divalent group selected from the group consisting of:

（式中、Ｒ²は脂肪族基、環式脂肪族基、単環式芳香族基、縮合多環式芳香族基、芳香族基が直接又は架橋員により連結された非縮合環式芳香族基からなる群より選ばれる４価の基を示す。）

(In the formula, R ² represents an aliphatic group, a cyclic aliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or a non-condensed cyclic aromatic in which aromatic groups are connected directly or by a bridging member. A tetravalent group selected from the group consisting of groups is shown.)

（式中、Ｒ¹、Ｒ²は上記の通り。）

(In the formula, R ¹ and R ² are as described above.)

  Examples of the diamine compound represented by the general formula (I) include o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 2-chloro-1,2 -Phenylenediamine, 4-chloro-1,2-phenylenediamine, 2,3-diaminotoluene, 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 3,4-diaminotoluene, 2-methoxy-1,4-phenylenediamine, 4-methoxy-1,3-phenylenediamine, benzidine, 3,3′-dichlorobenzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 3, 3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diamy Diphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfide, 3,3′-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- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis 4- (3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1, 2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] Propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (3-amino Phenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3- Hexafluorop Lopan, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-amino) Phenoxy) benzene, 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] Sulfoxide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- (3-aminophenoxy) phenyl Sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis [ 4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 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) phene Noxy] phenyl] ketone, bis [4- [4- (4-aminophenoxy) phenoxy] phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1 , 3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, and the like are used alone or in combination of two or more.

Examples of the tetracarboxylic dianhydride represented by the general formula (II) include those in the general formula (II) such as ethylene tetracarboxylic dianhydride in which R ² is an aliphatic group, and R ² is a cyclic fatty acid. Cyclopentanetetracarboxylic dianhydride, which is an aromatic group, such as 1,2,3,4-benzenetetracarboxylic dianhydride, pyromellitic dianhydride, where R ² is a monocyclic aromatic group, R 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, wherein ^2, is a condensed polycyclic aromatic group, 1,2,5,6 -Naphthalenetetracarboxylic dianhydride, 3,4,9,10-berylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8- Phenanthrenetetracarboxylic dianhydride, R ² is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, which is a non-condensed cyclic aromatic group directly linked with an aromatic group 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, in which R ² is a non-condensed cyclic aromatic group in which aromatic groups are linked by a cross-linking member, 2,2 ′, 3,3 '-Benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis ( 3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2 , 3-Dicarboxyphenyl) ethane Anhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 4,4 ′-(p-phenylenedioxy) diphthalic dianhydride 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride and the like, and these may be used alone or in admixture of two or more.

  The thickness of the polyimide film used for this invention needs to be 30 micrometers or less, Preferably it is 12-30 micrometers, More preferably, it is 12-25 micrometers. When the thickness of the polyimide film exceeds 30 μm, the bending properties are deteriorated.

In addition, the polyimide film used in the present invention has a gas permeation amount of dimethylacetamide at 5 torr and 200 ° C. of 0.1 kg / m ² · hr or more, preferably 0.15 kg / m ² · hr or more, more preferably 0.8. It is necessary to use 15 to 1.5 kg / m ² · hr. If the gas permeation amount is less than 0.1 kg / m ² · hr, the film surface is swollen during solvent drying and imidization after lamination.

  Furthermore, the polyimide film used in the present invention may be subjected to plasma treatment or etching treatment on the surface thereof.

  On the other hand, the type of metal foil used in the present invention is not particularly limited, and usually copper, nickel, aluminum, stainless steel, beryllium copper alloy, etc. are often used, and metal foil for forming a printed circuit. Copper foil is often used. About copper foil, both rolled copper foil and electrolytic copper foil can be used. In addition, in order to increase the adhesion between the metal foil and the polyimide that is in direct contact with the metal foil, the metal simple substance on the metal foil, its oxide or alloy, for example, when the metal foil is a copper foil, copper simple substance, oxidation An inorganic layer such as copper, nickel-copper alloy or zinc-copper alloy may be formed, and a coupling agent such as aminosilane, epoxysilane, mercaptosilane, etc. may be applied on the metal foil in addition to the inorganic material. .

  In this invention, as metal foil used for a laminated board, thickness becomes like this. Preferably it is 10 micrometers or more, More preferably, it is 10-35 micrometers, More preferably, it is 18-35 micrometers, and it is preferable that it is a rolled copper foil. If the thickness of the metal foil such as rolled copper foil is less than 10 μm, there may be a problem in wrinkles during production, strength in the lamination process, and the like, and a protective material may be used.

In the present invention, first, the metal foil and the polyimide film are laminated by a heated roll press through a heat resistant adhesive.
In this case, polyamic acid is preferable as the heat-resistant adhesive.

  The polyamic acid used for the adhesive in the present invention can be obtained by reacting an aromatic tetracarboxylic acid anhydride with an aromatic diamine.

Examples of acid anhydrides used in the present invention include tetracarboxylic acid anhydrides and derivatives thereof. In addition, although tetracarboxylic acid is specifically illustrated below, these esterified products, acid anhydrides, and acid chlorides can of course be used. That is, as the tetracarboxylic acid, pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4,4 '-Diphenylsulfone tetracarboxylic acid, 3,3', 4,4'-diphenyl ether tetracarboxylic acid, 2,3,3 ', 4'-benzophenone tetracarboxylic acid, 2,3,6,7-naphthalene tetracarboxylic acid 1,2,5,6-naphthalenetetracarboxylic acid, 3,3 ′, 4,4′-diphenylmethanetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-Dicarboxyphenyl) hexafluoropropane, 3,4,9,10-tetracarboxyperylene, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] Propane, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] hexafluoropropane, butane tetracarboxylic acid, and cyclopentane tetracarboxylic acid. Also included are trimellitic acid and its derivatives.
Furthermore, it can be modified with a compound having a reactive functional group to introduce a crosslinked structure or a ladder structure.

  On the other hand, examples of the diamine used in the present invention include p-phenylenediamine, m-phenylenediamine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, diaminotoluene, 4,4. '-Diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl ] Propane, 1,2-bis (anilino) ethane, diaminodiphenylsulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2,2-bis (p-aminophenyl) propane, 2,2-bis (p- Aminophenyl) hexafluoropropane, 1,5-diaminonaphtha , Diaminotoluene, diaminobenzotrifluoride, 1,4-bis (p-aminophenoxy) benzene, 4,4 ′-(p-aminophenoxy) biphenyl, diaminoanthraquinone, 4,4′-bis (3-aminophenoxy) Phenyl) diphenylsulfone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis (anilino) octafluoropropane, 1,5-bis (anilino) decafluoropropane, 1,7-bis (anilino) tetra Decafluoropropane, 2,2-bis [4- (p-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [ 4- (2-aminophenoxy) phenyl] hexafluoropropane, 2,2 Bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) -3,5-ditrifluoromethylphenyl] hexafluoropropane, p-bis (4-amino-2-trifluoromethylphenoxy) benzene, 4,4′-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4′-bis (4-amino-3-) Trifluoromethylphenoxy) biphenyl, 4,4′-bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4,4′-bis (4-amino-5-trifluoromethylphenoxy) diphenylsulfone, 2, , 2-bis [4- (4-amino-3-trifluoromethylphenoxy) phenyl] hexafluoroprop , Benzidine, 3,3 ′, 5,5′-tetramethylbenzidine, octafluorobenzidine, 3,3′-methoxybenzidine, o-tolidine, m-tolidine, 2,2 ′, 5,5 ′, 6, Diamines such as 6′-hexafluorotolidine, 4,4 ″ -diaminoterphenyl, 4,4 ′ ″-diaminoquaterphenyl, diisocyanates obtained by reaction of these diamines with phosgene, and further diaminosiloxanes And the like.

  The solvents used here are N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), dimethyl sulfate, sulfolane, butyrolactone, cresol, phenol. , Halogenated phenol, cyclohexanone, dioxane, tetrahydrofuran, diglyme and the like.

The polyimide film is usually a condensate of pyromellitic anhydride and 4,4′-diaminodiphenyl ether or a condensate of 3,3 ′, 4,4′-biphenyltetracarboxylic anhydride and p-phenylenediamine. However, the present inventors have used a method of using, as an adhesive, a polyamic acid that becomes a polyimide adhesive layer that gives the same chemical structure and equivalent properties as a polyimide film used for lamination by thermosetting. As a result of intensive studies, the adhesives include, in particular, condensates of pyromellitic anhydride and 4,4′-diaminodiphenyl ether, 3,3 ′, 4,4′-biphenyltetracarboxylic anhydride and p-phenylenediamine. A polyamic acid composed of a condensate with or a mixture thereof is particularly preferred, and the condensation reaction is carried out by using DMAc and NMP as polar solvents. The reaction temperature is 10 to 40 ° C., the concentration of the reaction solution is 30% by mass or less, and the molar ratio of aromatic tetracarboxylic acid anhydride to aromatic diamine is 0.95: 1.00 to 1 It was found that the reaction was carried out in a N ₂ atmosphere within the range of .05: 1.00. There are no particular limitations on the method of dissolving and adding the raw materials.

  Furthermore, in the present invention, a polyamic acid copolymerized or obtained by using the condensate or the like can be blended and used. In addition, for the purpose of improving various properties, inorganic, organic or metal powders, fibers, etc. can be mixed and used, and additives such as antioxidants or adhesives are used for the purpose of preventing conductor oxidation. It is also possible to add a silane coupling agent for the purpose of improvement. Furthermore, different polymers can be blended for the purpose of improving adhesiveness.

  The heat-resistant adhesive used in the present invention preferably has a viscosity of 100 to 5,000 mPa · s at 20 ° C. measured with a B-type viscometer (Tokyo Keiki Co., Ltd.).

In the method for producing a polyimide metal foil laminate according to the present invention, the polyamic acid is cast on a metal foil such as a copper foil so that the film thickness after imidation of the polyamic acid is preferably 5 μm or less, and imidization does not proceed ( (Preferably less than 5% imidization) After drying until the solvent content becomes 3 to 50% by mass at a temperature, the thickness is 30 μm or less, and the gas permeation amount of dimethylacetamide at 5 torr and 200 ° C. is 0.1 kg / m ^2.・ All polyimide flexible metal foil with excellent bending characteristics by laminating a polyimide film of hr or higher with a heated roll press at a temperature of 150 ° C. or lower and further drying and imidizing the solvent under a reduced pressure of 10 Pa or lower. Laminates can be manufactured.

  That is, the heat-resistant adhesive used in the production method of the present invention can be said to be a substantially polyamic acid having an imidization rate of less than 5%, more preferably less than 3%, and even more preferably less than 1% at the time of lamination. In addition, since it contains a solvent, the softening point is 150 ° C. or lower, more preferably 80 to 150 ° C., and still more preferably 80 to 120 ° C. The polyamic acid is obtained by reacting an aromatic diamine and an aromatic tetracarboxylic acid anhydride in a polar solvent, and the reaction solution can be used as it is as a varnish for an adhesive.

  It is preferable to apply the polyamic acid so that the thickness of the adhesive layer after imidization is 5 μm or less, more preferably 2 to 5 μm, and still more preferably 2 to 4 μm. If the thickness of the adhesive layer after imidization is larger than 5 μm, the curl of the laminate may be increased.

  In the present invention, preferably, the polyamic acid varnish is applied to a treated surface of a metal foil such as a rolled copper foil and dried, but the apparatus and method are not particularly limited, and the application is a comma coater, T die, roll coater, knife What is necessary is just to use a coater, a reverse coater, a lip coater, etc., and when drying passes through a heated roll press, the solvent content is 3 to 50% by mass, preferably 3 to 10% by mass, and imidization does not proceed (imide) The degree of conversion is less than 5%) The polyamic acid remains as it is, and it may be appropriately dried at a temperature of 120 ° C. or lower, more preferably 80 to 120 ° C. for adhesion.

  Here, if the solvent content exceeds 50% by mass, bubbles or blisters may occur during roll pressing or after-curing, and if a heat history is applied until the solvent content falls below 3% by mass, partially Since imidization starts and the softening point of the polyamic acid layer exceeds 150 ° C., high temperature and high pressure are required when laminating with a hot roll press, and the equipment cost may increase.

  Examples of the heating method of the roll press include a method in which the roll is directly heated with oil or steam, and the roll material is a metal roll such as carbon steel or a rubber roll made of heat-resistant fluoro rubber or silicone rubber. The

Moreover, the heating temperature at the time of roll press needs to be 150 degrees C or less which is the range of the softening point of the solvent-containing polyamic acid after drying, and below the boiling point of the solvent used, Preferably it is 100- 150 ° C. When the heating temperature exceeds 150 ° C., the film surface is swollen after pressing.
The roll press conditions are not particularly limited, but the linear pressure is preferably 5 to 100 kg / cm, particularly 10 to 70 kg / cm.

  About solvent drying and imidation after lamination, it is necessary to carry out in the pressure-reduced state of absolute pressure 10Pa or less, Preferably 0.001-8Pa. If the pressure at the time of solvent drying and imidization is higher than 10 Pa, the flexibility of the obtained all-polyimide flexible metal foil polyimide laminate will be rapidly lowered.

The form for performing the solvent removal and imidization may be a sheet or a roll, and there is no particular limitation on how to roll the roll, and a metal foil such as a copper foil may be inside or outside, May be in the form of a roll with a spacer in between.
In this case, in the method of the present invention, a solvent remaining after lamination and dehydration at the time of imidization are generated in solvent removal and imidization, and therefore rolls are preferably performed by loosely winding or sandwiching spacers of other materials. You may heat-process in a state.

  In addition, although the manufacturing method mentioned above is about the manufacturing method of a single-sided metal foil polyimide laminated board, this invention is applied suitably also to the manufacturing method of a double-sided metal foil polyimide laminated board. In the production of a double-sided metal foil polyimide laminate, the film surface of a single-sided product laminated with a polyimide film and the polyamic acid side of the one where a polyamic acid layer is formed on another metal foil and the solvent is removed are mutually connected. It is made to adhere by hot roll lamination to form a double-sided metal foil polyimide laminate. Lamination conditions, curing (imidization) conditions, and the like may be the same as in the method for producing a single-sided product.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In addition, in the following example, a part and% show a mass part and mass%, respectively.

[Examples 1 and 2]
Synthesis of polyamic acid 218.5 g of pyromellitic anhydride was added to 1 kg of N, N-dimethylacetamide, and the mixture was stirred under N ₂ atmosphere and kept at 10 ° C., and 200.5 g of 4,4′-diaminodiphenyl ether. Was dissolved in 1 kg of N, N-dimethylacetamide and gradually added so that the internal temperature did not exceed 15 ° C. Then, after making it react at 10-15 degreeC for 2 hours, it reacted at room temperature for 6 hours. When the viscosity after completion of the reaction was measured with a B-type viscometer (Tokyo Keiki Co., Ltd.), it was 3,000 mPa · s (viscosity at 20 ° C.).

Preparation of laminated plate A 35 μm rolled copper foil cut to 30 cm × 25 cm was coated with the polyamic acid varnish prepared as described above by an applicator so that the thickness of the liquid was 60 μm. What was coated with the applicator so that it might become 90 micrometers in thickness was dried as 120 degreeC x 5 minutes in Example 2 as oven. The polyamic acid layer had a residual solvent amount of 5 mass%, an imidization ratio of 3%, and a softening point of 120 ° C. A 25 μm apical NPI (manufactured by Kaneka Chemical Industry Co., Ltd.) cut to 30 cm × 25 cm was layered thereon, and a test roll laminating machine (heating roll press machine) manufactured by Nishimura Machinery was used, and 120 ° C. × 15 kg / cm × Lamination was performed at 4 m / min. This was decompressed to 5 Pa in a vacuum oven, heated to 350 ° C. over 1 hour, and heat-treated for 1 hour while maintaining 350 ° C. In Example 1, the obtained laminated plate had a copper foil of 35 μm and a polyimide layer of 30 μm, and in Example 2, the copper foil of 35 μm and the polyimide layer of 32.5 μm. Table 1 shows the results of evaluating the curl amount, MIT folding resistance, and IPC bending characteristics of the obtained samples by the following methods. The DMAc permeation amount of the polyimide film used was measured by the following method, and the results are shown in Table 1.

Measurement of curl amount of laminated board Originally, a desired electric circuit is formed on a flexible printed circuit board, but in this embodiment, the effect of the shape of the electric circuit on the flatness is taken into account. Take a flexible metal foil polyimide laminated board that is easy to generate, and make a flexible circuit board with a fully etched (completely removed copper foil) product, cut the laminated board obtained above into 15 cm x 15 cm, and then the copper foil surface After performing the whole surface etching, it was dried at 150 ° C. for 1 hour. The sample was placed on a surface plate, the heights of the four corners were measured, and the average value of the heights of the warp was taken as the curl amount.

MIT folding resistance A circuit defined in JIS C6471 was produced, and the number of folding in the MD direction was measured under the conditions of a bending radius of 0.8 mm, a bending speed of 175 times / minute, and a load of 500 g.

A circuit pattern defined in IPC FC 241 is prepared on the copper foil layer of the IPC flexural properties laminate, with the copper foil facing outside, a temperature of 80 ° C., a flexion radius of 1.5 mm, a flexion speed of 1,500 times / minute, Bending was repeated at a stroke of 20 mm, and the number of times that the resistance value of the circuit exceeded 10% or the number of times the circuit was broken was defined as the number of times of bending.

Measurement of DMAc Permeation Amount of Polyimide Film As shown in FIG. 1, 100 ml of DMAc 2 is placed in a screw mouth bottle 1 having a capacity of 300 ml, and a polyimide film having a thickness of 25 μm shown in Table 1 is formed on the upper end surface of the mouth of the bottle 1. 3 is placed, SUS mesh 4 is placed thereon, NBR packing 5 is placed thereon, and a holed cap (26 mm diameter of the lid cut end) 6 is screwed into the bottle 1 to form one bottle portion. The amount of solvent (DMAc) lost when heated at 200 ° C. × 5 torr × 1 hour in a vacuum oven ETACVT 220 manufactured by Enomoto Kasei Co., Ltd. was measured and converted to kg / m ² · hr. The results are shown in Table 1.

[Comparative Examples 1-6]
Comparative Examples 1 and 2 were laminated in the same manner as in Example 1 except that drying was performed under the conditions shown in Table 2, and MIT folding resistance, IPC bending characteristics, and DMAc permeation amount were evaluated. Comparative Example 3 was dried and laminated in the same manner as in Example 1 except that the polyimide film used was changed from Apical NPI to Upilex S. Further, Comparative Examples 4 and 5 are shown in Table 2 in an N ₂ inert oven. Conditions, and Comparative Example 6 was dried and laminated in the same manner as in Example 1 except that drying was performed in a normal oven under the conditions shown in Table 2, and the MIT folding resistance, IPC bending characteristics, and DMAc permeation amount were measured. Evaluation was performed. The results are shown in Table 2.

It is a schematic sectional drawing of the measuring tool of the gas permeation amount of the dimethylacetamide (DMAc) of a polyimide film.

Explanation of symbols

1 bottle 2 DMAc
3 Polyimide film 4 SUS mesh 5 NBR packing 6 Hole cap

Claims (4)

After laminating the metal foil and polyimide film coated with heat-resistant adhesive with a heated roll press, the residual solvent of the adhesive layer is removed by heat treatment, and heat-cured to produce a flexible metal foil polyimide laminate. As a heat-resistant adhesive, a polyamic acid having a solvent content of 3 to 50% by mass at the time of lamination and an imidization ratio of less than 5% is used, and a polyimide film has a thickness of 30 μm or less, and its 5 torr, 200 ° C. The gas permeation amount of dimethylacetamide at 0.1 kg / m ² · hr or more was used, laminated at a temperature of 150 ° C. or less with a heated roll press, and then subjected to heat treatment under a reduced pressure of 10 Pa or less in absolute pressure. A method for producing a flexible metal foil polyimide laminate, characterized by thermosetting.   Adhesive component is a condensate of pyromellitic anhydride and 4,4′-diaminodiphenyl ether, a condensate of 3,3 ′, 4,4′-biphenyltetracarboxylic anhydride and p-phenylenediamine or the like The method for producing a flexible metal foil polyimide laminate according to claim 1, wherein the polyamic acid is selected from a mixture of the above.   The method for producing a flexible metal foil polyimide laminate according to claim 1 or 2, wherein the metal foil is a rolled copper foil of 10 µm or more and the heat-resistant adhesive layer is 5 µm or less.   The method for producing a flexible metal foil polyimide laminate according to claim 1, 2 or 3, wherein the heat-resistant adhesive is a polyamic acid having a softening point of 150 ° C or lower at the time of lamination.

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