Flip chip packaging for MEMS microphones

We have developed a microphone package using flip chip technology instead of chip and wire bonding to create smaller MEMS microphones. With this new packaging technology the transducer chip and an ASIC chip are flip chip bonded on a ceramic substrate. The package is sealed by a polymer foil laminated over the chips and by a metal layer. The sound port is on the bottom side in the ceramic substrate. In this paper the packaging technology is explained in detail and results of electro-acoustic characterization and reliability testing are presented. We will also explain the way which has led us from the packaging of Surface Acoustic Wave (SAW) components to the packaging of MEMS microphones.