Stevens, Davis, Miller & Mosher, LLP
Semiconductor device with a coating of Pb-free Sn-base solder and manufacturing method therefor
A lead frame made from Ni, a Ni alloy, Cu, a Cu alloy, Fe or an Fe alloy, comprising an inner lead part with a surface treatment layer of Ag or a Ag-containing alloy and an outer lead part with a surface treatment layer of an alloy containing Ag and Sn, wherein the latter surface treatment layer has a brightness of not less than 0.6 and Sn has the body-centered tetragonal lattice with the crystal orientation indices of from 1.5 to 5 at the (220) plane, not more than 0.9 at the (211) plane and not less than 0.5 at the (200) plane. The surface treatment layer is plated with utilization of a plating solution which contains one or more selected from alkane sulfonic acid, alkanol sulfonic acid and sulfamine acid as the acid component, one or more of tin methane-sulfonate and SnO as a tin salt, and one or more slected from silver methane-sulfonate, Ag2O and AgO as a silver salt. The outer lead part may be subjected to a preliminary etching treatment with utilization of a treatment agent of one or more selected from chloric acid, nitric acid and sulfic acid prior to forming the surface treatment layer. The formed surface treatment layer may be treated by a treating agent containing sodium triphosphate.
Matsushita Electric Industrial Co., Ltd.
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Takashi Matsuo Tsuyoshi Hisahiro
Kubara Masuda Tokiwa Tanaka