Protective cover for electrical conductor bodies

摘要

An electrical circuit element, particularly a semi-conductor body 10 of silicon or germanium, having a PN junction 13 extending to a surface 14 of the body as in silicon diodes and transistors (see Division H1), is provided with a protective cover by forming a layer of silicon oxide 11, 17 on the element surface (see Division C7) and bonding to this layer, which is 1,000 to 30,000 rA thick, a layer of glass 19, which is 8,000 to 500,000 rA thick, preferably by depositing powdered glass on the oxide layer 17, e.g. by spraying, settling or silk screening, and fusing it to chemically bond the layers. A preferred method disclosed in Specification 992,044 is centrifuging the element with the oxide layer in an organic fluid containing a suspension of finely-divided glass particles. Preferred glass compositions are borosilicates containing the oxides PbO, Al2O3, K2O and/or ZnO, in order that the thermal coefficient of expansion of the glass may be similar to that of the element.ALSO: An electrical circuit element, particularly a semi-conductor body 10 having a PN junction 13 extending to a surface 14 of the body as in silicon diodes and transistors (see Division H1), is provided with a protective cover by forming a layer of silicon oxide 11, 17 on the element surface and bonding to this layer, which is 1,000-30,000rA thick, a layer of glass 19, which is 8,000-500,000rA thick, preferably by depositing powdered glass on the oxide layer 17 and fusing it to chemically bond the layers. In order that the thermal coefficient of expansion of the glass may be similar to that of the element suitable borosilicate glass compositions (see Division C1) may be used. When the circuit element is of silicon, the oxide layer may be integrally formed on the element by heating it to 900-1400 DEG C. in an oxiding atmosphere such as air saturated with water vapour or steam. For germanium the silicon oxide layer may be formed by evaporation. The oxide layer may also be formed by electrochemical treatment. Selected areas of the cover may be removed by etching with HF using a conventional etching mask down to the circuit element so that metal buttons 20 and 29-32 may be deposited by evaporation, e.g. to provide terminals, Fig. 3(b); a metal conducting layer 21 may be applied to the base of the element by evaporation or soldering, Fig. 2(d). Connecting the buttons 29 and 20 in Fig. 3(b) is shown a resistor 39, e.g. of Cr or SnO2 deposited on the glass layer 19. Other conducting connections (not shown) may be deposited on the glass by evaporation or sputtering. Specification 992,044 is referred to.