EXPOSED HEAT SINK HAVING SEALING RING

摘要

PROBLEM TO BE SOLVED: To prevent a molding compound from flowing to the exposed region of a heat sink by providing a sealing ring on the periphery of the exposed region. SOLUTION: Exposed surface of a heat sink can touch a resin molding material and a part thereof can flow out during encapsulation to cover the exposed surface of the heat sink. A sealing ring 203 is thereby provided on the periphery of the exposed region 201 of the heat sink 200. The ring 203 is about 0.05 mm wide and 0.02 mm high. It is formed by making a recess in a work by coining to form a flat base surface and a side wall perpendicular thereto. The ring 203 is a communicating region between the molding surface 204 and the surface 201 of the heat sink 200. The ring 203 serves as a dam for preventing the molding compound from flowing over the remaining part of the exposed region of the heat sink 200 during encapsulation.