| 摘要 |
PROBLEM TO BE SOLVED: To provide a junction process capable of ensuring high junction strength and high reliability in a method of joining a heat spreader and a lead piece using laser welding. SOLUTION: A semiconductor device has an assembly structure in which a heat spreader 3 is joined to an upper surface of an IGBT chip (semiconductor chip) 2 mounted on an insulating substrate 1, and a strap-like lead piece 4 as a wiring member is joined to an upper surface of the heat spreader. For the semiconductor device, the heat spreader is jointed to the lead piece by a laser welding method. Its joining process is separated into a first stage welding process of emitting a high-power density laser beam, and a second stage annealing process and executed. In the annealing process, a re-cured molten portion is irradiated with a laser beam of power density lower than that in the welding process, and its crystal texture is re-crystalized to remove a residual stress. COPYRIGHT: (C)2008,JPO&INPIT
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