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. 13, 1992
Filed:
Dec. 06, 1990
Cynthia M Melton, Bolingbrook, IL (US);
Carl J Raleigh, Cary, IL (US);
Steven Scheifers, Hoffman Estates, IL (US);
Motorola Inc., Schaumburg, IL (US);
Abstract
An improved electrical component package comprises a component attached to a substrate by a plurality of multisolder interconnections. Each interconnection comprises a preformed spacer bump composed of a first solder alloy, preferably a lead-base tin alloy containing greater than 90 weight percent lead. The spacer bump is bonded to a metallic electrical contact of the component and rests against a corresponding metallic electrical contact of the substrate, but is not directly metallurgically bonded thereto. Each interconnection further comprises a sheath portion formed of a second compositionally distinct solder alloy having a liquidus temperature less than the first alloy solidus temperature. A preferred second solder is a tin-lead alloy comprising between about 30 and 50 weight percent lead and the balance tin or indium. The sheath is bonded to the spacer bump and to the substrate contact to complete attachment of the component to the substrate and preferably extends to the component contact, encasing the bump, to produce an interconnection having an hour glass configuration to reduce thermal fatigue stresses at the solder bonds to the contacts. A method for forming the multisolder interconnection is presented wherein the sheath is derived from a solder microball situated on the substrate contact in juxtaposition to the spacer bump for reflow.