Abstract: A cooling structure is provided for a multichip module on which integrated circuit devices (i.e., LSI devices) having heat-radiation surfaces are mounted, wherein there are provided a heat sink, thermal conduction blocks and thermal compounds. Recess portions are formed at a surface of the heat sink in connection with the integrated circuit devices of the multichip module. Low melting point metal material such as solder is supplied to interiors of the recess portions of the heat sink. The thermal conduction blocks are partially inserted into the interiors of the recess portions under the condition where the low melting point metal material is heated and melted, so that the thermal conduction blocks temporarily float in the melted material. To avoid heat transfer toward the integrated circuit devices, a heat insulating sheet is provided on the thermal conduction blocks. Then, the low melting point metal material is solidified, so the heat insulating sheet is removed.

Abstract: A semiconductor plastic package, more particularly a preferred package structure and method for making a BGA package. A resin sealed BGA package where a supporting frame which fixedly supports semiconductor parts; i.e., an IC chip, a circuit board, or a circuit film, is sealed with resin, using a mold which is composed of an upper mold half and a lower mold half with the lower mold half having a plurality of projections, one at a position corresponding to each of the external terminals. The mold has a divisional structure which has an air vent between the divisional elements thereof.