LONDON Ė STMicroelectronics NV has claimed it is the first company that has mass-produced MEMS microphones in plastic packages. ST has patented a technology development that allows this while, at the same time, saves space and increases durability, the company said.
Typical applications are mobile phones and tablet computers, noise-level meters and noise-cancelling headphones.
ST's plastic-packaged MEMS, soon to arrive on the market, measure 2-mm by 2-mm. This gives rise to the possibility of embedding silicon membrane microphones inside silicon cavities in other devices, the company said.
ST's MEMS microphones are suitable for assembly on flat-cable printed-circuit boards and the package technology allows the sound-hole to be in either the top or the bottom of the package. Top-port packaging tends to suit applications in laptops and tablet computers, while bottom-port microphones are more suitable for mobile phones, ST said.
Compression and drop test show that the plastic-packaged microphones are more durable than traditional metallic-lid devices. When subjected to 40-newtons force microphones in metallic packages collapsed whereas ST microphones in plastic packages did not. Similarly when devices in both categories were exposed to 40 drops from a height of 1.5 meters with a static force of 15N applied on the package. The superior robustness holds for both flat-cable printed-circuit boards (PCB) and traditional rigid PCB designs.
The plastic-package microphones integrate an internal shielding cage for electromagnetic immunity and are compatible with standard surface-mount assembly machinery and conventional pick-and-place equipment.
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