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

摘要

[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. As 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.

主权项

1. A process for producing a solder preform having high-melting metal particles dispersed therein comprising:
preparing a premixed master alloy having high-melting metal particles dispersed in a solder such that the proportion of the high-melting metal particles is 5-30 mass percent based on the amount of the solder; placing the premixed master alloy into a first molten solder in an amount such that the proportion of the high-melting metal particles is 0.1-3 mass percent based on the first molten solder followed by stirring; casting the first molten solder having the high-melting metal particles mixed therein into a mold to form a billet; and working the billet to form a solder sheet and then forming a solder preform from the solder sheet.