Testing Microphones

A Scandinavian company was looking to test microphones which would be used in the hearing aid industry. Achieving a reproducible and well-defined sound pressure is required when testing microphones. This is a practical impossibility since standing waves need to be avoided which means that the dimensions have to be less than λ/8. MEMUNITY has solved this impossibility by using a reference microphone very close to the actual microphone under test. Using a very small sound source near to the microphone under test also improves the measurement. Frequency ranges up to about 10 kHz are possible.

Microphone and Match

Testing Microphones from both sides

If the design of the device requires access from both the back and front side of the wafer for test purposes, the patented doubleside probing technology from SUSS can be implemented. This was the case for a Danish Si microphone manufacturer who required electrical contact from the topside and sound stimulation from below. As the noise box used to generate the sound had to remain in contact with the wafer, SUSS used their programmable manipulators to move upwards out of the way of the prober stage which moved upwards for die stepping rather than the regular downwards movement.

Click here for a short video sequence (11.8 MB, wmf file)