Formation of solder bump

Abstract

Abstract PURPOSE:To realize the direct formation of a solder bump without providing a substrate metal by a method wherein ultrasonic waves are applied in such a way that an electrode part is brought into contact with molten solder containing dispersed solid particles so that the molten solder containing dispersed solid particles is attached selectively to the electrode by means of alloying. CONSTITUTION:After one face of a double-faced adhesive tape for hightemperature use has been attached to the reverse side of a silicon wafer 11, this assembly is attached to a glass sheet via the other face of the adhesive tape. The assembly is then dipped into spouting molten solder 23 by keeping it in a vertical position, and an ultrasonic vibrator 25 is inserted into the molten solder at a location near the silicon wafer 11 so that ultrasonic waves can be applied. As the type of solder, Pb-Sn eutectic solder which contains dispersed solid particles is to be used. Through this constitution, prior to this operation an electrode 33 is formed on a silicon substrate 31 via an insulating film 32, and the electrode 33 is not covered with a passivating film 34 which coats the whole surface. After the operation, a mountain-like solder bump 35 is bonded directly on the electrode 33.

Inventors

• 👤 Michio Sato
• 👤 道雄 佐藤
• 👤 Michihiko Inaba
• 👤 道彦 稲葉
• 👤 Kazuyoshi Saito
• 👤 和敬 斎藤
• 👤 Seiichi Hirata
• 👤 誠一 平田

Bibliographic Details