Abstract: A tin-silver alloy plating film improved in solderability and flex cracking characteristics is provided by producing it by an electroplating process which uses a current having a pulse waveform of a current passing period of not less than 3 ms and not more than 500 ms and a stopping period of not less than 1 ms and not more than 500 ms with a proviso that the stopping period is equal to or shorter than the passing period.

Abstract: The present invention relates to a lead frame for semiconductor devices having an outer lead part improved in solder wettability which comprises i. a substrate comprising an alloy comprising at least one member selected from the group consisting of nickel, copper, iron and (nickel and copper and iron), ii. an inner lead part having a surface treated layer A, the surface treated layer A comprising silver or an alloy comprising silver, and iii. an outer lead part having a surface treated layer B, the surface treated layer B comprising silver and tin, or copper and tin, wherein the surface treated layer B has on its surface an oxidized layer comprising tin and oxygen, the atomic ratio of oxygen to tin in the oxidized layer is 0.5-1.8 and the thickness of the layer is not more than 20 nm.

Abstract: The present invention relates to a method for producing a tin-silver alloy plating film having an excellent wettability and improved in solderability and said method comprises a step of heat treating the surface of the tin-silver alloy plating film preferably the heat treating temperature is 70-210° C.

Abstract: A tin-silver alloy plating film improved in solderability and flex cracking characteristics is provided by producing it by an electroplating process which uses a current having a pulse waveform of a current passing period of not less than 3 ms and not more than 500 ms and a stopping period of not less than 1 ms and not more than 500 ms with a proviso that the stopping period is equal to or shorter than the passing period.

Abstract: The present invention relates to a method for producing a tin-silver alloy plating film having an excellent wettability and improved in solderability and said method comprises a step of heat treating the surface of the tin-silver alloy plating film preferably the heat treating temperature is 70-210° C.

Abstract: 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.

Abstract: The present invention relates to a lead frame for semiconductor devices having an outer lead part improved in solder wettability which comprises

Abstract: In a lead frame formed out of at least one metal selected from the group consisting of nickel and nickel alloys, copper and copper alloys and iron and iron alloys, the inner lead part is provided with a surface treatment layer of Ag or an alloy containing silver and the outer lead part is provided at least with a surface treatment layer of an alloy containing silver and tin of the body-centered cubic structure preferentially oriented in the (101) plane and/or the (211) plane. According to the above-mentioned structure, a semiconductor device that uses a lead frame for electronic parts which does not contain lead, one of the environmentally harmful pollutants, has good characteristics including solder wettability and bonding strength and is of low cost and a process for producing the device are provided.