Metal fusion bonding – Process – Metal to nonmetal with separate metallic filler
Patent
1987-12-22
1989-04-04
Jordan, M.
Metal fusion bonding
Process
Metal to nonmetal with separate metallic filler
228123, 228220, B23K 3102
Patent
active
048178543
ABSTRACT:
Method of bonding a chip to a Cu heat sink comprises depositing a layer of Ni upon the sink, depositing a layer of Pt over the NI, and thereafter annealing the sink in a partial vacuum containing a reducing gas. After the annealing step, a metallic wetting layer of Au and a layer of In are sequentially deposited upon the Pt, and the chip is soldered to the heat sink by means of a flux free soldering process. The pure Pt is very dense and stable, does not have microholes therein which would otherwise allow the Cu ions to penetrate the Pt. For a BeO heat sink, a Ti layer is deposited over the sink rather than Ni, and a layer of Pt is thereafter deposited over the Ti layer. The Ti, Pt and BeO interact to form a good bond of high thermal conductivity, which also blocks ion migration upwardly toward the solder and the electronic chip.
REFERENCES:
patent: 4321617 (1982-03-01), Duda et al.
patent: 4544091 (1985-10-01), Hidler et al.
patent: 4623086 (1986-11-01), Tihanyi et al.
Mott Jeffrey S.
Sovak Maryanne
Tihanyi Peter L.
Vollmer Hubert J.
Jordan M.
Nathans Robert L.
Singer Donald J.
The United States of America as represented by the Secretary of
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