JP2000167980A - Metal laminated board employing low boiling point solvent varnish as precursor of adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve separation strength between an insulation layer and a metal layer by using thermoplastic resin employing varnish containing a solvent having a specific boiling point in an adhesive layer between the insulation layer and metal layer. SOLUTION: The metal laminated board uses thermoplastic resin having varnish as a precursor in an adhesive layer between an insulation layer and a metal layer. A varnish solvent is available in a boiling point of 170 deg.C or lower, more preferably, 150 deg.C or lower. For such a formation of the insulation layer, there is a method of applying and curing polyimide, polyamideimide, and amide varnish being an adhesive to the metal foil, and employing an adhesive sheet. In general, non-thermoplastic resin such as polyimide, polyamide, polyamideimide, nylon is used to the base film of an adhesive sheet. As metal of the metal layer, there are used stainless, Cu, Fe, Ni, Mo, Al, and the like, and adhesion between the metal layer and insulation layer is carried out by heat press, lamination, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal laminate for a printed wiring board in which a metal layer is laminated on both sides of an insulating layer. More specifically, the present invention relates to an adhesive between the insulating layer and the metal layer such as polyimide or polyamideimide. By using a liquid varnish as a precursor and using a varnish solvent having a boiling point of 170 ° C. or less, a reduction in drying temperature and an improvement in resin fluidity are realized.

[0002]

2. Description of the Related Art In a metal laminate which has been widely used for a printed circuit board and the like, a varnish as a precursor thereof is applied to a metal foil or an insulating layer by using a thermoplastic resin for an adhesive layer and dried. The method of forming an adhesive layer has been widely used.

[0003] In a metal laminate, it is desirable that the metal peel strength is 1.0 kg / cm or more.
Further, in the metal laminate, the bonding temperature between the metal layer and the insulating layer is desired to be at least 250 ° C. or less in order to avoid oxidation of the metal and deterioration of the insulating layer.

[0004] In response to such market demands, in a metal laminate plate in which a varnish is applied and cured to form an adhesive layer,
To ensure a peel strength of 1.0 kg / cm 2, the bonding temperature had to be raised to 250 ° C. or higher. This is because a high boiling point solvent having a boiling point of 200 ° C. or higher has been used for varnish. In order to remove the solvent of the varnish, it was necessary to set the drying temperature to a high temperature of 200 ° C. or higher, and it was inevitable that the resin would be crosslinked and hardened during drying. When the thermoplastic resin undergoes intermolecular cross-linking, the fluidity of the resin at the time of bonding decreases, the adhesion to the metal layer or the insulating layer decreases, and the problem that the bonding strength decreases occurs. In order to secure the adhesive strength, it was necessary to increase the adhesive temperature to secure the fluidity of the resin.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to improve the peel strength between an insulating layer and a metal in a metal laminate.

[0006]

Means for Solving the Problems The present inventors have conducted studies to solve the above-mentioned problems, and as a result, the varnish solvent has a boiling point of 170 ° C. or lower, more preferably 150 ° C. or lower. A method for obtaining a good adhesive strength by reducing the drying temperature was found. That is, there is a relationship between the drying temperature of the varnish and the curing and crosslinking density of the resin, and the higher the drying temperature, the higher the crosslinking density of the resin. for that reason,
In a thermoplastic resin, the fluidity at a high temperature is reduced, the adhesion of the resin at the time of bonding is deteriorated, and the bonding strength is reduced when the bonding temperature is the same.

To lower the drying temperature of the varnish, it is necessary to lower the boiling point of the varnish solvent. At present, the boiling point of the solvent used for the varnish is 200 ° C. or higher, and the drying temperature can be lowered by lowering the boiling point to 170 ° C. or lower.

According to the present invention, a thermoplastic resin having a high fluidity at the time of bonding can be obtained, so that a metal laminate exhibiting high peel strength can be obtained. That is, it is possible to obtain a substrate having excellent workability and high connection reliability when forming a pattern such as a printed circuit board or a TAB base material.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The metal laminate of the present invention is based on the use of a thermoplastic resin having a varnish as a precursor for the adhesive layer between the insulating layer and the metal layer, and the varnish solvent has a boiling point of 170 ° C or lower, more preferably 150 ° C or lower. I just need.

In order to form the insulating layer, a metal foil is coated with polyimide, polyamide imide, or amide varnish to serve as an adhesive layer.
There are a method of curing and a method of using an adhesive sheet. A non-thermoplastic resin is usually used for the base film of the adhesive sheet, and specifically, polyimide, polyamide, polyamideimide, nylon, or the like is used. More specifically, non-thermoplastic Ube Industries product polyimide film Upilex series, Kanekachi Chemical company polyimide film,
Examples include a polyimide film Kapton series manufactured by DuPont and an amide film Aramica series manufactured by Toray.

Regardless of the type of metal layer to be laminated, the same applies to the case of forming a multilayer laminate. As the metal of the metal layer, specifically, stainless steel, Cu, Fe, N
i, Mo, Al and the like. The bonding between the metal layer and the insulating layer is performed by hot pressing, laminating, or the like.

[0012]

Next, examples of the present invention will be described. However, the present invention is not limited to the following examples. Example 1 Ube Industries, Ltd. polyimide film, Upilex 50SG
A (50 μm thick) with N, N-dimethylacetamide (DMAc)
Polyamic acid varnish PA manufactured by Mitsui Chemicals using
AA was applied and dried to prepare an adhesive sheet having a total thickness of 70 μm. Cut this adhesive sheet into 5mm width and 70mm length,
Hot pressing was performed on a YEF 42 steel (width 25 mm, length 50 mm, thickness 0.15 mm) manufactured by Hitachi Metals, Ltd. at 0 ° C., 20 kg / cm ² , and 5 seconds using a small bonding machine. The peel strength of the thus obtained sample was measured under the conditions of a tensile speed of 50 mm / min. The results were as shown in Table 1.

Comparative Example 1 Ube Industries, Ltd. polyimide film, Upilex 50SG
A (50 μm thick) was coated with PAA-A, a polyamic acid varnish made by Mitsui Chemicals, using N-methylpyrrolidone (NMP) as a solvent, and dried to prepare an adhesive sheet having a total thickness of 70 μm. Cut this adhesive sheet into 5mm width and 70mm length,
Temperature, 20 kg / cm ² , 5 seconds, Hitachi Metals YEF 42 steel (width
(25 mm, length 50 mm, thickness 0.15 mm) was hot pressed with a small bonding machine. The peel strength of the sample thus obtained was measured at a pulling speed of 50 mm / min. The results were as shown in Table 1.

[0014]

[Table 1]

Example 2 Copper foil manufactured by Ohlin Co., USA, C7025 foil (18 μm thick) was coated with N, N-
A polyamic acid varnish PAA-Pm manufactured by Mitsui Chemicals using dimethylformamide (DMF) as a solvent was applied and dried to prepare an adhesive-coated copper-clad laminate having a total thickness of 30 μm. Cut this copper-clad laminate with adhesive into 5mm width and 70mm length,
kg / cm ² , stainless steel foil SUS304HT manufactured by Nippon Steel under conditions of 5 seconds
A (25 mm wide, 50 mm long, 20 μm thick) was hot pressed with a small bonding machine. The peel strength of the sample thus obtained was measured at a pulling speed of 50 mm / min. The results were as shown in Table 2.

Comparative Example 2 A polyamic acid varnish PAA-Pm manufactured by Mitsui Chemicals using N-methylpyrrolidone (NMP) as a solvent was applied to copper foil and C7025 foil (18 μm thick) manufactured by Ohlin Co., USA, and dried. Thickness 30
A copper-clad laminate with an adhesive of μm was prepared. This copper-clad laminate with adhesive is cut into 5mm width and 70mm length, 230 ° C, 20kg / c
m ^2, with 5 seconds of conditions new day Tetsusha made of stainless steel foil SUS304HTA
(25 mm in width, 50 mm in length, 20 μm in thickness) were hot pressed with a small bonding machine. The peel strength of the sample thus obtained was measured at a pulling speed of 50 mm / min. The results were as shown in Table 2.

[0017]

[Table 2]

[0018]

As shown in the examples, the use of the varnish using the low-boiling solvent of the present invention makes it possible to obtain a metal laminate having a high adhesive strength.
Even when a fine pattern such as a TAB substrate is formed, workability is good and a product excellent in connection reliability can be obtained.

Claims (3)

[Claims] 1. A thermoplastic resin used as an adhesive between an insulating layer and a metal layer of a metal laminate, wherein a solvent of a varnish as a precursor thereof has a boiling point of 170 ° C. or less. Metal laminate. 2. The metal laminate according to claim 1, wherein said solvent is N, N-dimethylacetamide. 3. The metal laminate according to claim 1, wherein said solvent is N, N-dimethylformamide.