| 摘要 |
1,250,651. Printed circuit assemblies. WESTERN ELECTRIC CO. Inc. 30 Oct., 1968 [31 Jan., 1968], No. 51394/68. Heading H1R. A plurality of separate contact areas on a header are formed by first forming a conducting pattern of the shape of the required contact areas on the header including portions interconnecting the areas, then plating metal on to the pattern and finally heating the interconnecting portions by passing a current therethrough so as to melt them and thus isolate the contact areas. Ceramic substrate 12 is screen printed with moly-manganese metal 17 and sintered to form a pattern including contact areas 16 surrounding apertures 15 connected by runners 22 to a peripheral ring 21 made up of arcuate portions 23, 24 of dissimilar cross-section. The substrate 12 is then placed in a barrel plating apparatus and the pattern plated uniformly with a layer 18 of nickel, Fig. 4. Terminal pins 11 provided with an annular brazing preform over portion 13 are inserted into holes 15 until the pin heads 14 abut the preform which in turn abuts plated layer 18. The heads 18 are then brazed to the areas 16 simultaneously with the brazing of a metal coating on the base of the substrate 12 to platform 25. After testing a gold layer 19 is plated on the header. In order to disconnect the terminal areas 16, a current from source 26 is applied between adjacent pairs of pins in succession so that intermediate portions 24 are burned away. Integrated circuit chips are then mounted on the header. In the header of Figs. 5 and 6 (not shown), a plurality of discrete contact areas are isolated from a peripheral grounding ring, necked down portions in this case being provided between the grounding ring and contact areas along the radial runners. The top portion of this assembly after the nickel plating operation is coated evaporatively with titanium and gold and then etched so as to leave the titanium and gold only over the contact areas. |
