Precious alloyed metal solder plating process

Abstract

A relatively simple and inexpensive process for plating precious alloyed metals, such as AuSn, AuSnIn, AgSn, AuIn and AgIn. Anodes are formed from each of the metal components in the alloy and disposed in a conducting solution. The mass of each metal components is determined by Faraday's law. The target is also disposed in the conducting solution. Plating current is independently applied to each anode. The plating is conducted under an ultraviolet light sources to optimize the process. The plating alloys can be used for various purposes including attaching a semiconductor die to a substrate. Since the process does not involve exposure of the semiconductor die to a relatively high temperature for a relatively long time, the process does not pose a risk of contamination of the semiconductor by the adhesive or wax used to hold the die in place on the carrier during processing. Moreover, unlike earlier known processes which utilize epoxy, the precious alloyed metals do not wet the entire die but only the metal contact areas, thus avoiding potential short circuit to the die.

Dependencies are inferred from the claim text.