PURPOSE: To improve the reliability of joining strength and the yield of the junction by joining one end face having a prescribed area of the external metallic terminal to the pad part of the ceramic substrate with a joining material.
CONSTITUTION: A paste of tungsten (W), etc., is screen-printed on the surface of the ceramic substrate 2 consisting essentially of ceramics such as alumina, etc., so as to form the paste into a desirable pattern to form the pattern of the pad 3. On the other hand, the nail pin 4 made of 'Kovar(R)', that has about 4.57mm total length and is the external metallic terminal consisting of a body part having an about 0.45mm diameter and a calyx-like part whose one end face has ≥0.3mm2 area, is fabricated. Then the nail pin 4 is joined to the pad 3 of the ceramic substrate 2 with an Ag-Cu eutectic solder 5 at 800°C to produce the objective junction structure.
KIMURA KAZUO
MORISHIGE TOSHIO
KUROKAWA YASUHIRO
TOBASE HIROMORI
NEC CORP