The 2.6 by 1.6 mm2 microphone will allow mobile phone manufacturers to design smaller, lighter products without paying a cost premium. “The small footprint allows the use of more than one microphone per device, thereby increasing the sound quality to the end user, and the height of only 0.9 mm enables ultra thin device designs,” says Jacob Philipsen, president of Sonion Micro Electro Mechanical Systems (MEMS).

The all-silicon microphones provide several benefits over electret condenser microphones (ECM). Their standard, automated surface-mounting (SMT) compatibility reduces assembly cost and improves assembly process quality. “We have developed a digital microphone for cell phones, which no one has managed to do with ECMs because of the difficulty of having the required 5 high-quality input/output pins (Ground, Vdd, clock, left/right, and data) on a non-surface-mountable device like an ECM,” Philipsen tells APPLIANCE. “Silicon microphones are more stable over time and less sensitive to variations in temperature and humidity than ECMs.”

The microphone is made of three pieces of silicon. There is a microphone chip, an application-specific integrated circuit (ASIC) and a carrying substrate. He notes, “The microphone chip and the ASIC are flip-chip mounted onto the carrying substrate to create a shielded, all-silicon chip scale package (CSP) with soldering pads for SMT. “The microphones are reportedly highly immune to electro-magnetic interference (EMI) because of the shielded connection.