We have developed a rapid silicon to steel bonding process used to attach silicon microsensors onto steel. The specific application is to bond silicon based strain sensors to steel structures for real time strain sensing. Steel samples are electroplated with eutectic Pb/Sn alloy (Mp 183°C) and are bonded to silicon dice coated with Cr/Au or Cr/Cu/Ni/PbSn layers. Bonding took place in the inert environment of a rapid thermal annealing (RTA) oven at 220°C for about 20 seconds, which caused minimal damage to the steel samples. The silicon to steel bond survived >1000με of static loading at the steel surface and 1000 cycles of >1000με cyclic strain at the steel surface without failure. Corrosion resistance of the silicon to steel bond was tested by immersion in various oils and salt solutions, and the bonding method thus far has been successful.

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