Measurement of metal migration on thick-film piezoresistors and their terminations

Metal migration from the thick-film termination can affect not only the electrical characteristics but also the gauge factor or piezoresistive coefficient of thick-film sensors. Four sets of sensors with different ratios were designed to test the influence of the terminal metal migration effects on the gauge factors and resistivity of thick-film resistors. In all the cases, the shortest resistors have a lower gauge factor and a large deviation of resistances. The longer resistors will have better electrical parameters. SEM (scanning electron microscope) studies showed this interaction at the interface between the terminal and the resistor. The same distance of terminal diffusion is larger for a short resistor than for a longer one.<
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