Hello, I am investigating failures occurring on plastic encapsulated thick film substrates. The failures are pin-pin shorts due to Pb migration from high Pb solder attaching the I/O pins to the alumina. The migration happens after an unbiased autoclave test where the components have first been solder dipped. The migration appears as random deposits of Pb between the leads and usually follows the edge line of the overglaze. My question is: Is it possible to get electromigration in an unbiased autoclave or is this more likely to be dissolution of the Pb due to residual contaminants? Any help on this one would be greatly appreciated. Rory Doyle ----------------------------------------------------- Rory Doyle [log in to unmask] National Microelectronics Research Centre, Prospect Row, Cork, Ireland. Direct Line: + 353 21 904110 Switch: + 353 21 903000 Fax: + 353 21 270271 Home page: http://www.nmrc.ucc.ie/ ------------------------------------------------------