Abstract: A method wherein a circuit substrate device is provided having a semiconductor element and a circuit substrate between which a protective resin is placed.The protective resin has a smaller coefficient of linear expansion than that of the circuit substrate and a greater coefficient of linear expansion than that of the semiconductor element. Therefore, the protective resin may mitigate the influences of thermal stress due to differential in the thermal coefficients of expansion between the semiconductor element and circuit substrate to prevent warpage of the circuit substrate.

Abstract: A soldering method is disclosed as adapted for attaching semiconductor devices such as transistors to their lead mounts. A layer of a solder paste, premixed with rosin flux, is first printed or otherwise formed on each of a series of interconnected semiconductor mounts which may be in the form of a sheet metal punching. The semiconductor devices are placed on the respective solder layers. Then the solder layers are heated to a prescribed temperature higher than both the melting point of the solder and a flux activation temperature at which the flux starts bubbling within the solder. For thus heating the solder layers, the series of semiconductor mounts with the semiconductor devices placed thereon via the solder layers may be fed longitudinally over a suitably heated surface.