Method of resin-sealing semiconductor device

A method of resin-sealing a semiconductor device having a circuit board with an IC thereon, comprising:

• preparing a metal mold formed of an upper metal mold having a pressing member, and a lower metal mold situated under the upper metal mold and having a cavity for mounting the circuit board therein, a pinpoint gate formed at a lower portion of the cavity and a runner section formed below the cavity and communicating with the pinpoint gate,
• positioning the circuit board in the cavity of the lower metal mold and setting the circuit board such that the IC faces downward,
• pressing a rear surface of the circuit board where the IC is not mounted by the pressing member,
• supplying a resin tablet to a pot formed in the lower metal mold and pushing the resin tablet by a plunger from below to feed a resin obtained from the resin tablet to the runner section, filling the resin in the runner section to the cavity from below through the pinpoint gate formed below the cavity, and
• sealing the IC mounted beneath the circuit board by the resin while absorbing a change of a thickness of the circuit board by the pressing member for pressurizing the rear surface of the circuit board by using a spring.