Metal fusion bonding – Process – Metal to nonmetal with separate metallic filler
Patent
1985-05-20
1986-08-05
Ramsey, Kenneth J.
Metal fusion bonding
Process
Metal to nonmetal with separate metallic filler
228124, 228209, 148 63, 427 92, 427377, B23K 120
Patent
active
046038051
ABSTRACT:
Nickel layers used in electronic devices are frequently plated in solutions containing phosphorus. Residual phosphorus trapped in the plated nickel layer reduces solderability with respect to Pb-Sn solders. Voids are frequently found in the soldered joints. Solderability of such phosphorus containing nickel layers is enhanced and the number of voids is much reduced by heating the nickel surface first in an oxidizing atmosphere and then in a reducing atmosphere prior to soldering. The oxidation temperature should exceed 347.degree. C. in order to oxidize the residual phosphorus and drive off the volatile phosphorus oxides. Hydrocarbons and volatile sulfides are also removed. The reducing step removes the non-volatile nickel oxides, leaving a clean surface for soldering which is substantially free of nickel oxide, phosphorus and phosphorus oxides, sulfides, and organics.
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patent: 3736167 (1973-05-01), Bachman et al.
patent: 4024631 (1977-05-01), Castillero
Handy Robert M.
Motorola Inc.
Ramsey Kenneth J.
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