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. 20, 1998
Filed:
Sep. 09, 1996
Karl Grant Hoebener, Georgetown, TX (US);
Eric Max Hubacher, Austin, TX (US);
Julian Peter Partridge, Austin, TX (US);
International Business Machines Corporation, Armonk, NY (US);
Motorola, Inc., Shaumburg, IL (US);
Abstract
A product created through the reflow of low melting point solder on select contacts of a printed circuit board. In one form, the printed circuit board has fine pitch devices, including flip-chip integrated circuits, connected to a board having conventional coarse pitch surface. The fine pitch contacts of the board are exposed through holes in a stencil characterized in its ability to withstand solder reflow temperatures, not be wettable by solder, and have a coefficient of thermal expansion relatively matching the printed circuit board. Low temperature solder paste is screen deposited into the stencil openings. With the stencil fixedly positioned on the board, the solder paste retained by the stencil pattern is reflowed to selectively form on the underlying contacts of the printed circuit board. Thereafter, the stencil is removed from the board and the board is subject to previously practiced depositions of flux and paste in preparation for fine and coarse pitch component placement and ensuing solder reflow. The fine contact pitch and coarse contact pitch differ by nominal factor of two or more.