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:
Jun. 30, 1998
Filed:
Feb. 21, 1997
Cheng P Wen, Mission Viejo, CA (US);
Wah S Wong, Montebello, CA (US);
Raytheon Company, Lexington, MA (US);
Abstract
Mushroom-shaped, solder-capped, small-diameter (approximately 50 to 75 microns or less), metal bumps are used in the flip chip monolithic microwave integrated circuits (MMICs) attachment process to provide devices having improved solder volume uniformity. The operation of the MMIC device is extended to millimeter-wave frequencies. The self-alignment property of the solder reflow flip chip attachment process is retained, and enhanced by the solder cap that extends beyond the periphery of the metal bump. Solder flux instead of solder paste patterns are printed on the assembly substrate to facilitate flip chip attachment. The metal bumps comprise electroplated silver pillars having a first diameter capped with electroplated solder having a second diameter, where the second diameter is larger than the first diameter, and are formed using a multi-layer negative photoresist, multiple exposure processing sequence.