| 摘要 |
<p>PURPOSE:To improve the thermal fatigue resistance and the bonding reliability by a method wherein the bottom surface of an electrode metal foil is reduced smaller than the metallic film surface corresponding thereto, and thus the bottom and side surfaces of the metal foil are adhered to the metallic film surface by solder. CONSTITUTION:The electrolytic Cu foil is pasted on a polyimide film 301 by an epoxy resin 302, thus e.g. a cathode electrode 303 and a gate electrode 304 are formed, and the angle of inclination theta of the side surface is set as approx. 70 deg.. The foils 303 and 304 are plated by Pb-Sn solder 305. The multilayer cathode electrode 105 and gate electrode 106 of Ni-Ag are formed on an SCR substrate 100. The substrate 100 is positioned to a composite electrode 200, and the solder plate 305 is fused in the H2 at 350 deg.C resulting in the adhesion of the electrode foil and the metallic film. In this constitution, since a solder layer is formed also on the side surface of the electrode foil, the bonding strength is improved. Besides, since the solder layer on the inclined side surface sufficiently absorbs the thermal stress, the resistance against the thermal fatigue is remarkably improved. The sectional shape vertical to the foil bonding surface is inverse trapezoidal, therefore soldering processes are simplified.</p> |
