A team of researchers at A*STAR Institute of Microelectronics has investigated a couple of metal alloys that could give micro-electromechanical system (MEMS) sensors better protection in the toughest environments.

They wanted to find cheaper, more durable alternatives to the metal solders, such as gold-tin or copper-tin, which are typically used to seal the case.

Typical MEMS sensors measure temperature, pressure or vibration and they are hermetically sealed inside a strong metal casing to prevent air or moisture degrading the sensors' electronics. Vivek Chidambaram and his co-workers tested a 70:30 aluminium-germanium mixture, which has a melting point of about 420°C. This temperature—the eutectic point—is much lower than that for either metal on its own.

Unlike most conventional packaging materials, aluminium and germanium are compatible with the processes used to manufacture the MEMS. Using the aluminium-germanium sealant should make MEMS manufacturing easier and cheaper, and could also improve the device's performance, noted Chidambaram.

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