METHOD FOR PACKAGING ELECTRONIC PARTS

摘要

A method for hermetically packaging electronic parts such as IC chips within a space defined by a multilayer substrate and a cap is disclosed. A welding rib is formed on the printed circuit board having conductor portions so as to surround those conductor portions over which the electronic parts are to be mounted in a later step. Metal films are formed by nonelectrolytic plating on the conductor portions. A peripheral portion of a cap is placed on the welding rib. A laser beam is radiated onto the contact portion between the peripheral portion and the welding rib so as to weld them together. At this time, a portion of the welding rib which is subject to laser radiation is not covered with the metal film. Welding is thus performed in the absence of phosphorus, which is inevitably contained in the metal film formed by nonelectrolytic plating and is a principal cause of cracking at a welded portion.