Resistors for Micropower Circuits

摘要

Micropower resistors of 4.7, 10, 22, 47, and 100 megohms resistance have been prepared, tested and delivered. The resistors, including substrate, were processed from raw materials to the finished product. Substrates were pressed, fired, and centerless ground to less than 50 mils diameter. Thallium oxide glaze resistive films were applied and fired, and were then helixed to the desired resistance values. Lead wires were attached by percussive welding, and a conformal silicone coating was applied as an encapsulation. The resulting miniature resistors are mechanically strong and have generally good to excellent electrical properties. Some instability problems were encountered with the 4.7 megohm samples prepared initially, but these were generally corrected in the higher value resistors. The resistance temperature characteristic performance of the 10 to 100 megohm resistors was in the range of -100 to -250 ppm/C, outside of the limits prescribed in the technical guideline. Problems were also encountered in resistance tolerance at 100 megohms, terminal strength, resistance to solder heat, and resistance at 10 MC of the 47 and 100 megohm units. In all other tests, however, including temperature cycling, low temperature operation, moisture resistance with and without power, voltage coefficient, current noise, stray capacitance and 1000 hour load life, satisfactory performance was demonstrated at all specified resistance levels. (Author)