Process for producing a solder preform having high-melting metal particles dispersed therein

Abstract

[Problems] A conventional process for producing a solder preform in which a predetermined amount of high-melting metal particles are directly put into molten solder and stirred, requires a long time for dispersing the high-melting metal particles by stirring. Therefore, in the conventional method for producing a solder preform, dissolution of the high-melting metal particles into the molten solder occurred during stirring, and their particle diameters became small. If a semiconductor chip and a substrate are soldered with a solder preform containing metal particles having such decreased diameters, the space between portions being soldered becomes narrow, and a sufficient bonding strength is not obtained. [Means for Solving the Problems] In the present invention, a premixed master alloy having a higher proportion of the high-melting metal particles in solder is first prepared, then the premixed master alloy is put into molten solder to disperse the high-melting metal particles. Aa a result, the high-melting metal particles can be uniformly dispersed in solder in a short length of time. Accordingly, a solder preform which is obtained by the process for producing a solder preform according to the present invention can maintain a predetermined clearance between portions being soldered, and a sufficient bonding strength is obtained.

Dependencies are inferred from the claim text.