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Browse Prior Art Database

Cu-Au Intermetallic Capped Pad

IP.com Disclosure Number: IPCOM000106395D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 29K

Publishing Venue

IBM

Related People

Ohkuma, H: AUTHOR

Abstract

This article describes Cu-Au intermetallic capped pads of substrate to be used for C4 (Controlled Collapse Chip inter-Connection) joining. Top thin Au layer such as 0.2 micron thickness is deposited on the solder-wettable Cu layer of pads and then heated up in an inert atmosphere such as nitrogen in order to form Cu-Au intermetallic layer without forming oxidized surface layer. Fig. 1 shows an example of this pad construction. Fig. 2 shows some convectional pad construction.

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Cu-Au Intermetallic Capped Pad

      This article describes Cu-Au intermetallic capped pads of
substrate to be used for C4 (Controlled Collapse Chip
inter-Connection) joining.  Top thin Au layer such as 0.2 micron
thickness is deposited on the solder-wettable Cu layer of pads and
then heated up in an inert atmosphere such as nitrogen in order to
form Cu-Au intermetallic layer without forming oxidized surface
layer.  Fig. 1 shows an example of this pad construction.  Fig. 2
shows some convectional pad construction.

      This Cu-Au intermetallic copper pads can keep longer
solderability than bare copper pads.  This Cu-Au intermetallic capped
pad can prevent from being oxidized compared with bare Cu pads, and
material cost saving can be obtained compared with thick Au layer
such as 1 to 8 micron thickness.