Abstract: An improved transfer molding apparatus is provided for molding a preheated resin under pressure to thereby encapsulate a small element, such as a semiconductor device or package. In one aspect of the invention, the improvement consists of providing a shortened pot into which a piston is forcibly pressed to generate a flow of preheated resin in the encapsulating process, the improvement comprising the replacement of a single-element top drive plate, as found in a conventional apparatus, by a two-piece top drive plate which enables a shortening of the pot and corresponding reduction in the amount of air that would otherwise be trapped between the plunger and the resin during the process. The elimination of this air significantly reduces foaming, porosity, voids, and other defects in the cured resin which finally surrounds the electrical elements encapsulated thereby.

Abstract: A preheaterless manual transfer mold die for encapsulating semiconductor elements in a process for packaging semiconductors. The preheaterless manual transfer mold die includes a multi-plunger assembly adapted for upward and downward movement to press the resin. A tablet loader is inserted into an upper mold die in order to charge tablets into plunger bushes of the upper mold die. After charging, the loader is pulled out of the upper mold die. The upper mold die receives the tablets from the tablet loader. The tablets are pressed by the multi-plungers. A lower mold die, clamped to the upper mold die, receives the resin tablets in a gel state from the upper mold die and fills cavities of chases with the resin to mold semiconductor elements.