PURPOSE: To maintain a specified solder thickness and heat conduction characteristic while preventing cracking and damage of a product by soldering and pressing materials to be joined at the melting temp. of solder via a joining material consisting of solder and particles having the m.p. higher than the m.p. of said solder.

CONSTITUTION: Materials 1, 2 to be joined are soldered at the melting temp. of solder 4a via a solder joining material which is a mixture composed of said solder and particles 4b having the m.p. higher than the m.p. of the solder. The materials 1, 2 are pressed from both sides to maintain the thickness of the soldered layer at the diameter of the particles incorporated in the solder. The specified solder thickness is maintained and the specified heat conduction characteristic is maintained without cracking and damage of the product by pressing.