| 摘要 |
1467168 Making semi-conductor bases; forging; extruding Y SATO 3 July 1974 [10 July 1973 22 Nov 1973] 29562/74 Headings B3A B3H and B3P A method of making a base 12, Fig. 1, for a semi-conductor 10 comprises forming a blank 30 for the base, forming a recess 14 in the intended upper surface of the base with a projection 114 Fig. 4, extending from the bottom of the recess, and forming a stem portion 18A on the intended undersurface of the base wherein the recess is initially formed with a projection from its bottom surface and the projection is absorbed into the bottom surface as the recess attains the desired depth. The blank comprises a thermally and electrically conductive metal 26, e.g. Cu, and a weldable layer 28, e.g. Cu-Ni, formed by blanking a plurality of blanks from a clad or composite metal sheet. The layer 28 is removed to expose the base metal 26 for later attachment of the semi-conductor element 16. The blank is then introduced into a die assembly 36, Fig. 8 comprising a lower die 38 having a cavity 38a and an upper die 40 having a recess 40a. A knockout 42 extends through the lower die and includes a telescopically extending knockout pin 44. During downward movement of the die 40 a shallow recess 14A and shallow stem 18A are produced and since the pin 44 is momentarily retracted a projection 114 is formed in the recess. Upon further downward movement the projection is removed and the pin is lengthened and the recess is deepened. In an alternative embodiment, the lower die has a concave end profile (46), Fig. 9 (not shown), which produces a profile (114<SP>1</SP>) on the blank 30 of convex shape. Also, the base may be formed of a single metal rather than of a composite and thus obviate the removal of the upper layer 28. A base plate (236), Fig. 10 (not shown), of steel or iron may be mounted within the recess in the base of the mounting of the device (216). After working in the die assembly the stem portion is threaded by rolling. |
