Solder film manufacturing method, heat sink furnished with solder film, and semiconductor-device-and-heat-sink junction
AssigneeSumitomo Electric Industries, Ltd.
InventorsKatsuhiro Itakura, Yukifumi Chiba, Satoshi Fujii
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Abstract
The solder film manufacturing method has a step for laminating a plurality of unit layers, each unit layer formed by laminating a plurality of layers including layers of only Zn, Bi or Sn, or layers of alloys of two of the metals Zn, Bi and Sn. This manufacturing method also preferably also has a step for forming an Sn layer as the top surface layer. A heat sink has a solder film manufactured by this process. A solder junction connects a semiconductor device characterized by having a semiconductor element mounted on this heat sink with a heat sink having this solder film.
Claims28
A solder-film manufacturing method, being a process for multi-laminating unit layers formed by laminating a plurality of types of laminae made from either Zn, Bi or Sn singly, or an alloy composed of two metals selected from Zn, Bi and Sn.
A solder-film manufacturing method comprising:
- a process of forming a single lamina selected from a Zn lamina, a Bi lamina, an Sn lamina, an alloy lamina of Zn and Sn, and an alloy lamina of Bi and Sn;
- a process of forming a unit layer composed of Zn, Bi and Sn by repeating the single-lamina formation process with the lamina being changed, and laminating the laminae;
- and
- a process of repeating the unit-layer formation process to laminate the unit layers.
A heat sink furnished with a solder film being for mounting semiconductor devices mounted fluxlessly, the solder film being composed of Pb-free solder having a composition of 2 to 10 wt % Zn and 2 to 40 wt % Bi, with the remainder being Sn.
A heat sink furnished with a solder film being for mounting semiconductor devices mounted fluxlessly, the solder film being composed of Pb-free solder having a composition of 3 to 9 wt % Zn and 2 to 14 wt % Bi, with the remainder being Sn.
A heat sink furnished with a solder film being for mounting semiconductor devices mounted fluxlessly, the solder film being composed of Pb-free solder having a composition of 5 to 7 wt % Zn and 8 to 14 wt % Bi, with the remainder being Sn.
A heat sink furnished with a solder film being for mounting semiconductor devices mounted fluxlessly, the solder film being composed of Pb-free solder having a composition of 6 to 7 wt % Zn and 8 to 10 wt % Bi, with the remainder being Sn.
Dependencies are inferred from the claim text.