Molding apparatus for enclosing semiconductor chips with resin

A molding apparatus of the multiplunger type including a stationary mold, a movable mold opposed to the stationary mold, a plurality of pots formed in one of the molds for supplying a resin material, a plurality of cavities defined by the molds, at least one transfer channel holding each of the pots in communication with the corresponding cavity for transferring the resin material in a molten state, and plungers corresponding to the pots in position and number for applying a pressure to the resin material, the molding apparatus comprising a movable plunger holder having the plungers fixed thereto, slide members each intimately fitting in a communication bore and slidingly movable forward and backward, the communication bore being in communication with the transfer channel, pressing-pushing means in contact with said slide members for pushing the slide members each toward the corresponding transfer channel with a pressure sufficient to maintain the sliding members in a freely movable position at a specified molding pressure such that during injection the sliding members are freely movable forward and backward in response to variations from the specified molding pressure, and pressure detecting means actuatable by the sliding movement of the slide member for detecting the internal pressure of the transfer channel.