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:
Oct. 23, 2001
Filed:
Sep. 27, 1999
Sunil A. Patel, Los Altos, CA (US);
Chok J. Chia, Cupertino, CA (US);
Kishor V. Desai, Fremont, CA (US);
LSI Logic Corporation, Milpitas, CA (US);
Abstract
Provided is an apparatus and method for modifying the manufacture of chip carrier bond pads to increase the quality and reliability of semiconductor packages and ball joints in particular. This is accomplished by minimizing the corrosion of the barrier metal layer on the functional bond pads during gold deposition with the use of sacrificial pads electrically connected with the functional bond pads. According to one embodiment of the invention, a semiconductor package has copper conductive pads on a substrate that are exposed through a dielectric. Both functional and sacrificial (nonfunctional) copper conductive pads are provided. A barrier metal layer composed of nickel is electrolessly plated onto these conductive pads, and a bond metal layer of gold is deposited onto the nickel using electroless, generally immersion, gold plating. The surface area of the nickel on the sacrificial pads is less than that on the functional pads, and the nickel on the sacrificial pads corrodes first during electroless gold deposition. Without nickel corrosion on the functional bond pad, gold can more uniformly be deposited on the surface of the nickel layer. A eutectic solderable material placed on the gold can form a uniform bond with the nickel because the nickel on the functional bond pad is largely corrosion free.