Solder composition of mixed powders

摘要

A solder composition having a low melting point and a high remelting point sufficient to permit electronic circuit elements to be fixed on a printed circuit board at a low soldering temperature to prevent thermal damage of the electronic circuit elements during the mounting and prevent the elements from dropping off from the board due to any heat applied thereto after soldering. The solder composition includes a low melting solder powder containing a metal additive for melting-point depression, and a reactive alloy powder. The low melting solder powder is melted to form a soldering layer which serves to mount electronic circuit elements on a printed circuit board at a relatively low soldering temperature. At the soldering temperature, the metal additive is reacted with the reactive alloy powder to cause the soldering layer to have a remelting temperature higher than a melting point of the solder composition or solder powder.