Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead
Patent
1999-08-02
2000-10-10
Picardat, Kevin M.
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
438737, 438779, 438786, H01L 2144
Patent
active
061304794
ABSTRACT:
A method is provided for forming a solder joint to a pad, in which the thickness of the intermetallic layer formed by nickel in contact with solder is significantly reduced. A first layer of nickel is provided on the pad; a second layer of a noble metal (preferably gold) is then provided overlying the first layer. The first layer and the second layer are then annealed, thereby forming an alloy layer including nickel and the noble metal between the first layer and the second layer. Contacting the second layer with a molten solder (where the solder includes tin) then causes the noble metal to dissolve in the solder and the solder to subsequently wet the alloy layer, forming an intermetallic layer including nickel, the noble metal and tin. Only a thin intermetallic film grows, thus improving the reliability of the solder joint.
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Blackshear Edmund David
Chalco Pedro Armengo
Anderson Jay H.
Collins D. M.
International Business Machines - Corporation
Picardat Kevin M.
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