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:
Jul. 31, 1984
Filed:
Jun. 30, 1982
Somnath Bhattacharya, Wappingers Falls, NY (US);
Dudley A Chance, Danbury, CT (US);
Nicholas G Koopman, Hopewell Junction, NY (US);
Sudipta K Ray, Wappingers Falls, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
The top surface metallurgy of LSI chip carriers is improved by multiple and phased interface of metal layers which enable such metallurgies to be suitable for joining by solder reflow and wire bonding techniques. The modifications result in separating the solder bonding metallurgy from the fan-out conductor metallurgy with an intermediate layer of a metal such as Cr or Ti which prevents the formation of intermetallic alloys which are mechanically weak or brittle and tend to fracture because of thermal fatigue stresses caused by thermal cycling during either multiple (up to 50) solder bonding reflow operations or operation of the circuit. The fan-out metallurgy conductors are preferably composed of Cr-Cu-Cr layers covered by at least one upper metal layer which is separated from the Cu of the conductor by means of a metal such as phased layers of Cr or Ti deposited before the other upper metal layer or layers. Solder ball bonding surfaces are composed of additional metal in the form of Au, Cu and Ni. The solderless bonding surfaces are composed of a metal selected from Au, Cr, Ti, Al and Co.