Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Patent
1992-07-27
1993-08-03
Picard, Leo P.
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
361773, 361761, 174255, 257690, H05K 702
Patent
active
052335046
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 directly metallurgically bonded to a metallic electrical contact of the component and rests against a corresponding metallic electrical contact of the substrate, but is not 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.
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Research Disclosure, "Solder Column Extension", No. 260, Dec. 1995.
Melton Cynthia M.
Raleigh Carl J.
Scheifers Steven
Fekete Douglas D.
Motorola Inc.
Picard Leo P.
Southard Donald B.
Whang Young S.
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