JPH0382189A - Board of flexible printed wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable a board to be improved in high temperature characteristics and manufactured under gentle conditions by a method wherein conductors are pasted together with specific adhesive agent. CONSTITUTION:A heat resistant adhesive agent, which is excellent in heat resistance, able to bond under gentle conditions (low temperature, low pressure, short time), and represented by a formula I, is used as an adhesive agent for bonding a metal foil to a polyimide film, where R in the formula I denotes one type, two types or more of bivalent organic groups. Various kinds of polyamide-imide resins besides 'HYMAL' (product of HITACHI KASEI Co.) and 'TORON' (product of Amco Co.) can be synthesized through a publicized method using anhydrous trimellitic acid monochloride and diamine acid. To put is concretely, diaminodiphenyl ether can be used as diamine acid, and acrylic monomer or the like can be used as thermosetting prepolymer, but maleimide or polymaleimid is preferable to secure the physical properties of a heat-resistant adhesive agent composition after it is cured, where the physical properties concerned such as heat resistance and resistance to solvent which is used for cleaning electronic components are especially required to secure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a flexible printed wiring board substrate with excellent high-temperature properties and a method for manufacturing the same.

(Prior Art) With the rapid development of electronics in recent years, the environmental conditions in which flexible printed wiring boards are used have become harsher. For this reason, conventional substrates for flexible printed wiring boards (hereinafter abbreviated as MCF) cannot withstand the increasingly harsh usage environment, and are particularly problematic in terms of heat resistance, such as low adhesive strength at high temperatures. It has become.

Efforts have been made to improve heat resistance such as adhesive strength at high temperatures, but the workability is poor or the bonding temperature is too high, making it difficult to manufacture.

In order to solve this problem, as conventional techniques, for example, Japanese Patent Application Laid-Open No. 57-143328, Japanese Patent Application Laid-open No. 61-10862,
No. 7 discloses a polyamide modified with an epoxy resin to improve heat resistance, and JP-A-61-95029
The publication uses thermoplastic polyimide resin with a special structure, and JP-A-61-30122 uses thermosetting polyimide resin with a molecular structure that can be bonded at about 250°C. It is known that the adhesion properties at high temperatures are improved by adding a bismaleimide compound.

Furthermore, in order to improve the high-temperature properties of MCF, so-called direct coated MCF is known, which is manufactured by directly coating and curing polyimide resin on metal foil -L without using an adhesive.

(Problems to be Solved by the Invention) However, according to the above-mentioned prior art, high temperatures of 350°C or higher are required to cure the polyimide resin.
Due to the high energy costs and poor working conditions, it has not been possible to achieve both mild manufacturing conditions (low temperature, low pressure, and cooking time) and high heat resistance for actual production. .

In view of the above problems, the present invention provides excellent high temperature characteristics,
Moreover, it is an object of the present invention to provide an MCF that can be manufactured under mild conditions and a method for manufacturing the same.

(Means for Solving the Problems) As a result of extensive research, the present invention has found that in order to provide excellent high-temperature properties, the adhesive for bonding metal foil and polyimide film must have excellent heat resistance and be gentle. I'm convinced that the above problems can be solved by using the heat-resistant adhesive shown below that can be bonded under the following conditions (low temperature, low pressure, slow time).
+I made it clear.

A heat-resistant adhesive composition comprising a polyamideimide resin represented by the general formula (I) (R represents one type or a divalent organic group of 2F1i or more), a thermosetting prepolymer, and a curing initiator for the prepolymer. The present invention was completed based on the discovery that the above-mentioned problems could be solved by using the present invention.

The present invention will be described in detail.

The polyamideimide resin that can be used in the present invention is rHYM
ALJ (manufactured by Hitachi Chemical Co., Ltd., name of product) and rTORO
In addition to NJ (manufactured by Amoco, trade name), various types can be synthesized from trimellitic anhydride monochloride and diamic acid by known methods. Specifically, diamic acids include diaminodiphenyl ether, diaminodiphenylsulfide, diaminodiphenylsulfone, diaminodiphenylmethane, dimethylbenzidine, dimethoxybenzidine, phenylenediamine,
Toluylene diamine, 2,2-bis[(aminophenoxy)phenyl]propane, 2,2-bis[(aminophenoxy)phenyl]hexafluoropropane, 1.3-
Bis(aminopropyl)tetramethyldisiloxane, bis(aminophenoxy)benzene, bis[(aminophenoxy)phenyl]sulpon, etc. can be used.

In addition, as thermosetting prepolymers, acrylic acid monomer, methacrylic acid monomer, maleimide, polymaleimide,
Phenol novolak, epoxy, etc. can be used, but in order to ensure the physical properties of the heat-resistant adhesive composition after curing, especially heat resistance and resistance to solvents used for cleaning electronic parts, etc. (solvent resistance), Maleimide or polymaleimide is preferred.

As this maleimide or polymaleimide, N-
Phenylmaleimide, N-cyclohexylmaleimide,
N-carboxyphenylmaleimide, N-hydroxyphenylmaleimide, bis(maleimidophenyl)sulfone, bis(maleimidophenyl)methane, bis(maleimidophenoxyphenyl)propane, bis(maleimidophenoxyphenyl)sulfone, bis(maleimidophenoxyphenyl) hexa Fluoropropane, bis(maleimidophenoxyphenyl)-benzene, bis(maleimidophenoxyphenyl)tetramethyldisiloxane,
BMI-M-20 (Mitsui Toatsu Chemical Flavor, trade name) etc. can be used. Furthermore, bis(maleimidophenoxyphenyl)propane and bis(maleimidophenoxyphenyl)hexafluoropropane are preferable in terms of solubility in solvents and in terms of compensating for the fragility that is a drawback of maleimides.

As the polymerization initiator, any of the above-mentioned substances that accelerate the curing of the thermosetting prepolymer can be used, but organic peroxides are suitable as those that can cure the heat-resistant adhesive composition under mild conditions at low temperatures and in a short period of time. is preferred. Specifically, benzoyl oxides, 1-butyl peroxides, walnut peroxides, t-butylperoxycyclohexane, t-butylperoxyhexane, etc. can be used.

As a solvent for dissolving the heat-resistant adhesive composition and turning it into a solution,
It is necessary that the polyamide-imide resin can be sufficiently dissolved and volatilized at a temperature below the bonding temperature.Cellosolve solvents such as methyl cellosolve and ethyl cellosolve, and amide solvents such as dimethylformamide meet these requirements. Solvent, chloroform, trichloroethane, tetra? Chlorinated solvents such as Roloethane can be used.

Furthermore, additives such as pigments, fillers, leveling agents, coupling agents, and curing accelerators may be used in these heat-resistant adhesive plastics as required.

The present invention is characterized in that the heat-resistant adhesive composition described in item 1 is used as an adhesive between a plastic film and a metal conductor layer, and an MCF with excellent heat resistance can be obtained.

In addition, an MCF using this heat-resistant adhesive composition can be prepared by applying an adhesive composition solution to a plastic film or metal conductor layer (metal foil or metal plate; the same applies hereinafter), removing the solvent, After drying, it can be manufactured by laminating the metal conductor layer or plastic film and bonding under pressure at a temperature higher than the drying temperature. Alternatively, if the heat-resistant adhesive composition is applied onto a plastic film in advance using a roll coater or gravure coater, the solution is removed and dried, and the adhesive film (or sheet) is formed, the plastic film can be coated. It can be manufactured by sandwiching an adhesive film between the metal conductor layer and the metal conductor layer, and then bonding them together at a temperature higher than the drying temperature and under pressure.

The conditions such as drying temperature for removing the solvent in the present invention are as follows:
The temperature may be 200°C or less, and the time may be 1 hour or less, although it may vary depending on the scale of the solvent used.

Also, when bonding the metal conductor layer and the plastic film, bonding is possible if the temperature is higher than the drying temperature, but 15
A temperature of about 0 to 230°C is preferable in terms of workability and oxidation of the metal foil. Bonding can be achieved with an adhesive force of 5 kg/c+a or more, but if the surface to be bonded has a rough surface, voids are likely to occur unless the bonding pressure is high. Further, if the bonding pressure is high, residual stress at the time of bonding becomes large and dimensional changes when patterning the metal layer become large, which is not preferable. From these points, the adhesive pressure is 5 to 50 kg/c.
A range of d is preferred. Temperature and pressure can be applied using a hot press, a hot roll, or the like.

(Function) In the present invention, since the heat-resistant adhesive composition described in "2" is used as an adhesive between a plastic film and a metal conductor layer, two-dimensional crosslinking of the thermosetting prepolymer in the heat-resistant adhesive composition is achieved. occurs and wraps around the polyamideimide molecules in a network shape.
A so-called ■PN structure is formed and an MCF with excellent heat resistance and chemical resistance is obtained.

Here, the heat resistance of half 111 was determined by floating the test piece of 1 in 20IIIIIIf "half 1] 1 bath with the copper bath facing down" for 30 seconds, and then observing r1 no blistering.

The copper foil peel strength was measured by IPC-FC-241B.

Chemical resistance is 20III with etched copper foil on the front side.
(rl test j1 in trichlorethylene at 30°C)
After immersion for 0 minutes, the adhesive layer was observed.

(Example theory r!1']) Hereinafter, the present invention will be taxed based on Examples and Comparative Examples.

(Preparation of heat-resistant adhesive composition) Adhesive 1 Polyamideimide resin rHYMALJ (manufactured by Hitachi Chemical Co., Ltd., trade name) 100 g, 2,2-bis[4-(4-
A solution of a heat-resistant adhesive composition was prepared by mixing 60 g of maleimidophenoxy)phenyl]propane, 0.6 g of Perhexine 25B (Kawasui Oil ■, trade name), and 400 g of chloroform.

Adhesive 2 Polyamideimide resin was mixed with trimellitic anhydride monochloride, 2.2-bis[4-(4-maleimidophenoxy)phenyl]propane, 1.3-bis(3-aminopropyl)tetramethyldisiloxane (molar ratio 10:8:2
) was synthesized by a known method. 100 g of this polyamideimide resin, 80 g of 2,2-bis[4-(4-maleimidophenoxy)phenyl]propane, 0.8 g of perhexine 25B, 5N, N-dimethylformamide 40
0 g was mixed to adjust the melting point of the heat-resistant adhesive composition.

(Preparation of adhesive film) Adhesive film 1 After casting adhesive 2 onto a stainless steel belt using a roll coater, it was heated at 140°C for 5 minutes, then at 200°C for 30 minutes.
After drying for several minutes, it was peeled off from the stainless steel belt to produce an adhesive film. The thickness of this film was approximately 25 μm.

(Example 1) After applying adhesive 1 to polyimide film-1-,
The mixture was dried at 00°C for 15 minutes to remove chloroform.

Next, the rolled copper foil with a thickness of 35 μm and the melon were combined at 200°C.
MCF was produced by hot pressing at 20 kg/cJ for 15 minutes. The characteristics of MCF are shown in the table.

(Example 2) After applying adhesive 2 to a rolled copper foil with a thickness of 35 μm,
It was dried at 180°C for 20 minutes to remove N,N-dimethylformamide. Next, it was combined with a polyimide film and hot pressed at 200° C. and 30 kg/c+J for 25 minutes to produce an MCF.

The characteristics of MCF are shown in the table.

(Example 3) Using adhesive film 1, rolled copper foil with a thickness of 35 μm and polyimide film were heated at 180° C., 15 kg/cJ, 1 m/
Bonding was carried out using a hot roll under conditions of 10 minutes.

Next, after-curing was performed at 200° C. for 30 minutes to produce an MCF.

The characteristics of MCF are shown in the table.

(Comparative Example 1) This comparative example is Example 8 of JP-A No. 61-30122.
The characteristics of the MCF manufactured using this method are shown in the table.

(Comparative Example 2) An MCF was produced in the same manner as in Comparative Example 1, except that the same adhesive as in Comparative Example 1 was used and the bonding temperature was 220°C.

The produced MCF had bubbles all over its surface and was not able to withstand the test.

(Effects of the Invention) As explained above, the flexible printed wiring board substrate according to the present invention not only has excellent high-temperature properties but also excellent chemical resistance. Further, according to the present invention, since it is possible to manufacture using a heat-resistant adhesive, it is possible to work at a lower temperature than before, and workability can be significantly improved.

Claims (3)

[Claims] 1. In a flexible printed wiring board substrate made by bonding conductors made of plastic film and metal using an adhesive, the adhesive has the following general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) ( R represents one or more divalent organic groups.)
A substrate for a flexible printed wiring board, characterized in that a heat-resistant adhesive composition comprising a polyamide-imide resin, a thermosetting prepolymer, and a curing initiator for the prepolymer is used. 2. A solution adhesive is applied onto a conductor layer made of metal or a plastic film, and after the solvent is removed and dried, the plastic film or the conductor layer is overlaid on the adhesive layer and bonded together by applying pressure and heating. The method for manufacturing a flexible printed wiring board substrate according to claim 1. 3. 3. The method for manufacturing a flexible printed wiring board substrate according to claim 2, wherein the adhesive is in the form of a film.