JPH0315537B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for directly laminating polyetherimide and metal without using different adhesives. In the production of printed circuit boards, etc., technology for strongly adhering resin plates and metal foils is important, and conventional adhesives include butyral/NBR/phenolic resin and NBR/acrylic/phenolic resin. . However, when we tried using a polyetherimide (hereinafter abbreviated as "PEI") resin board, which is known for its good heat resistance, we found that conventional adhesives could not provide sufficient adhesive strength. There was found. In addition, if other types of adhesives are used to bond PEI, which has extremely excellent heat and chemical resistance, even if adhesive strength is obtained, the heat resistance and chemical resistance of the laminate as a whole will decrease, and the PEI will deteriorate. There is a possibility that the performance will not be fully demonstrated. The present invention provides a method for firmly adhering PEI and metal without impairing heat resistance and chemical resistance. It is characterized in that a PEI solution is interposed and the PEI-metal laminate is bonded under heat and pressure. According to the present invention, a laminate in which a PEI layer and a metal layer are directly laminated without using different materials can be obtained, so when used as a printed circuit board, for example, PEI has good resistance to soldering heat and etching. Its excellent properties are fully demonstrated. The present invention will be explained in detail below. The PEI referred to in the present invention is A typical example is one having the following structure. This PEI is used by being formed into a film shape, plate shape, or other shape depending on the intended use by extrusion molding, injection molding, or the like. Further, metals to be laminated on PEI include copper, aluminum, etc. To laminate a PEI layer and a metal layer, a
Both layers are heat-pressed at 100-270°C with PEI solution interposed. As a solvent for the PEI solution, methylene chloride (CH ₂ Cl ₂ , boiling point 40°C), 1,1,2-trichloroethane (ClCH ₂ CHCl ₂ , boiling point 114°C), or a mixture of both is used. Methylene chloride has a high ability to dissolve PEI, but has a low boiling point and is easily volatile, so the bonding work must be carried out quickly.Also, 1,1,2-trichloroethane has a high boiling point, but its ability to dissolve PEI is not so great. Therefore, according to the studies conducted by the present inventors, a mixed solution of methylene chloride and 1,1,2-trichloroethane is most suitable, and in particular, 20 to 50% by weight of methylene chloride
A mixture of 1,1,2-trichloroethane and 80 to 50% by weight is optimal. The concentration of PEI in this solution is 3 to 30% by weight (assuming the total amount of PEI and solvent is 100% by weight)
degree is preferred. In addition, the thickness of PEI solution is about 5 to 50μ,
Preferably, the thickness is about 10 to 40 μm; if it is too thin, the adhesive strength will be insufficient, and if it is too thick, the solution will protrude during heat-pressing, which is disadvantageous. Hereinafter, specific steps of the method of the present invention will be illustrated and explained using examples, and the effects thereof will be clarified. Example 1 Injection molded PEI plate (thickness 3mm) and copper foil (thickness
15μ), first coat one side of the copper foil (surface treated) with a 10% PEI solution (solvent: a mixture of 30% methylene chloride and 70% 1,1,2-trichloroethane). by coder
It was applied to a thickness of 30μ. Then, a PEI plate was placed on the coated surface and pressed from the copper foil side with a rubber roll to remove air and squeeze out excess PEI solution. Next, the laminate was heated and pressurized gradually using a press at various temperatures, and after reaching a pressure of 30 kg/cm ² , it was held at that pressure for 15 minutes to remove the solvent, and then cooled and the laminate was taken out. did. Table 1 shows the relationship between the heating temperature and the quality of the obtained laminate. The quality of the laminate was evaluated by the following method. 1 Adhesive strength: Pull the metal foil at a speed of 50 mm/min.
The peel strength when peeled at 180° was converted into a value per 10 mm width. 2 Tape removability: The metal foil of the laminate is etched, adhesive tape is pasted on top of it, and the tape is vigorously peeled off to see if the metal foil peels off. Displayed as defective. 3 Solder heat resistance: According to JIS C6481.

【table】

[Table] As is clear from Table 1, the heating temperature is 100 to 260.
The laminates No. 2 to 5, which were crimped at ℃, were excellent in various qualities. No. 7, which used a conventional adhesive, had insufficient adhesion strength, and No. 8, which crimped the copper foil and PEI plate without using a PEI solution, required heat crimping at extremely high temperatures. As a result, the thickness of the PEI plate decreased, and air bubbles remained at the adhesive interface, which caused creases in the copper foil. Example 2 Aluminum foil was used as the metal foil, and layers were laminated with varying concentrations of PEI solution, and the layers were gradually pressurized at 180°C with a press, and after reaching a pressure of 15 Kg/cm ² , the pressure was held for 30 minutes. . The other points were the same as in Example 1. Table 2 shows the relationship between the PEI solution concentration and the quality of the obtained laminate.

[Table] The PEI solution concentration is preferably 3 to 30% by weight. If the concentration is too high, it will be difficult for air bubbles to escape, and as a result, the metal foil will tend to crease and wrinkle, which is not very preferable when using a thin foil as the metal.

Claims (1)

[Claims] 1. A polyetherimide solution dissolved in methylene chloride and/or 1,1,2-trichloroethane is interposed between the polyetherimide layer and the metal layer, and a polyetherimide-metal laminate is produced by heat-pressing. Method.