Fishing – trapping – and vermin destroying
Patent
1994-05-02
1995-11-28
Picardat, Kevin M.
Fishing, trapping, and vermin destroying
437182, 437189, 437192, 437193, H01L 2144
Patent
active
054707870
ABSTRACT:
A semiconductor device (32) has an as-deposited solder bump (34) having the intrinsic potential for forming an extended eutectic region for simplified DCA applications. The as-deposited solder bump (34) has first tin layer (40) overlying the UBM of the bonding pad (14) on the device. The first tin layer reacts with a metal layer (36) in the UBM to form an intermetallic for adhering the solder bump to the bonding pad. A thick lead layer (42) overlies the first tin layer to provide the substantial component of the solder bump. A second tin layer (44) overlies the lead layer to provide localized eutectic formation at the top surface of the bump during reflow. A device having at least this solder bump structure can be directly attached to either ceramic or PC board substrates. Additional layers of tin and /or lead may be supplemented to the basic bump structure to optimize the eutectic formation rate.
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Grivas, Dennis et al., "The Formation of Cu3Sn Intermetallic on the Reaction of Cu with 95Pb/5Sn Solder," Journal of Electronic Materials, vol. 15 No. 6, Nov. 1986, pp. 355-359.
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Clark Minh-Hein N.
Motorola Inc.
Picardat Kevin M.
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