The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 12, 2006
Filed:
Sep. 07, 2004
Wen-chou Vincent Wang, Cupertino, CA (US);
Wen-Chou Vincent Wang, Cupertino, CA (US);
Altera Corporation, San Jose, CA (US);
Abstract
The present invention is directed to a new bonding pad structure that includes a copper pad and a pad surface finish comprising multiple layers of solder. The multiple layers of solder include at least a layer of eutectic solder (or a layer of pure-Sn solder) covering the copper pad and a layer of high-Pb solder covering the layer of eutectic solder (or the layer of pure-Sn solder). Since the layer of high-Pb solder is significantly thicker than the eutectic solder layer (or the layer of pure-Sn solder), there is insufficient tin supply in the eutectic solder (or the layer of pure-Sn solder) for forming a thick Cu/Sn intermetallic layer on the copper pad. Instead, a thin Cu/Sn intermetallic layer is formed on the copper pad and there is less likelihood of forming a crack in the thin Cu/Sn intermetallic layer.