Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1978-11-03
1979-12-04
Tupman, W. C.
Metal working
Method of mechanical manufacture
Assembling or joining
228180A, 29628, 357 71, B01J 1700
Patent
active
041764439
ABSTRACT:
A silicon wafer, having a front surface with disjointed contact areas and a uniform rear surface, is provided at the contact areas of its front surface with respective pads each comprising a base layer of aluminum, a first intermediate layer of chromium or titanium, a second intermediate layer of nickel and an outer layer of gold or palladium. The rear surface is covered with a base layer of gold (or of a gold/arsenic alloy in the case of N-type silicon), a first intermediate layer of chromium, a second intermediate layer of nickel and an outer layer of gold or palladium to which a film of low-melting bonding agent (lead/tin solder) is applied. After testing and elimination of unsatisfactory wafer sections, the remaining sections are separated into dies placed on a conductive substrate; an extremity of a respective terminal lead, encased in a similar bonding agent, is then placed on the outer layer of each contact pad. All soldering operations are simultaneously performed in a furnace.
REFERENCES:
patent: 3926747 (1975-12-01), Newby
patent: 4009058 (1977-02-01), Mills
patent: 4042954 (1977-08-01), Harris
Del Bo Vittorio
deMartiis Carlo C.
Gandolfi Luciano
Iannuzzi Giulio
Ross Karl F.
SGS-ATES Componenti Elettronici S.p.A.
Tupman W. C.
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