Rap 'n Tap
[ Home | Contents | Post | Reply | Next | Previous | Up ]
From: Al Klase
Date: 12/9/99
Time: 6:49:12 PM
Remote Name: 209.250.78.157
This page has te following discription of the plague:
http://www.imappl.org/~changa/JAY/packaging.html
"Purple Plague"
A problem encountered in the production of gold-aluminum bonds is the formation of the "purple plague." Gold and aluminum react to intermetallic compounds.
AuAl2 is purple-colored
Au2Al is tan-colored
AuAl2 appeared to be the culprit associated with a faulty bonds. However, this compound is highly conductive. The actual culprit is a low-conductivity, tan-colored compound, Au2Al, which is also present. Limiting the die temperate helps to prevent the formation of intermetallic compounds.