Development of Backside Process For Use With Solder Paste Die Attach

 

Jason Fender and Terry Daly

 

Freescale Semiconductor, Inc.

Tempe Fab

2100 E. Elliot Road, Tempe, AZ, 85284

480-413-3521; 480-413-5029

jason.fender@freescale.com; terry.daly@freescale.com

 

 

Keywords: backside, metallization, solder attach

 

 

Abstract

††††††††††† In this paper we describe methods used to modify backside metallization in order to accommodate a change in solder assembly applications.As a cost savings effort, one of Freescale Tempe Fabís gallium-arsenide (GaAs) product lines was to be lead-tin (PbSn) solder-attached using methods at a silicon assembly site.The change in assembly methods introduced the problem of PbSn mixing into our standard backside gold (Au) metallization (ground) from die edges.Use of nickel-vanadium (NiV) as a solder barrier combined with process modifications designed to seal die edges was required to eliminate Sn and Pb mixing with backside Au.

 

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