Abstract: An improved contact is obtained to power devices having a raised dielectric region adjacent the die contact region by providing a contact dimple on the otherwise flat metal lead used for die contact. The dimple is arranged above the die contact and soldered thereto. The radius of curvature and depth of the dimple is adjusted so that the contact lead is far enough away from the edge of the surrounding raised dielectric at the edge of the die contact to provide a laterally concave outward air-solder interface in that location. This prevents solder creep onto the dielectric surface and avoids die edge shorting. Several dimple shapes are described.

Abstract: An improved contact is obtained to power devices having a raised dielectric region adjacent the die contact region by providing a contact dimple on the otherwise flat metal lead used for die contact. The dimple is arranged above the die contact and soldered thereto. The radius of curvature and depth of the dimple is adjusted so that the contact lead is far enough away from the edge of the surrounding raised dielectric at the edge of the die contact to provide a laterally concave outwardly air-solder interface in that location. This prevents solder creep onto the dielectric surface and avoids die edge shorting. Several dimple shapes are described.

Abstract: A process is disclosed for the complete curing of a layer of polyimide in a short time at a low temperature. A solution of polyimide or polyimide precursor having a well-defined viscosity is applied to a substrate to form a layer of predetermined thickness. The substrate and layer are heated in such a manner to cause a continuous increase in temperature of the layer at a predetermined rate to a temperature between about 170.degree. C. and about 225.degree. C. By maintaining a continuous temperature rise during this heating, the total curing of the polyimide layer is accomplished at a temperature less than about 225.degree. C. To determine the optimum rate of temperature rise to cure a given polyimide layer, a similar polyimide layer is formed as a dielectric layer on a ceramic substrate having interdigitated capacitor electrodes formed thereon. The dielectric dissipation factor of the polyimide material is measured dynamically during the curing process.