Although Infineon sells no MEMS microphones itself, it supplies over 1 billion MEMS dies to other manufacturers yearly, In fact it supplies approximately 75 percent of the die used by others including ACC, Goertek, BSE, Hosiden and Gettop with most of the remaining 25 percent of the bare dies business supplied by Omron, NJRC and MEMSensing.
"Infineon does not sell its own microphones -- it only markets MEMS microphone dies and their associated ASICs to other companies," Robert Helm who is heading the Silicon Microphone business at Infineon told EE Times. "The reason behind this is that we focus on that at which we are best -- we are a semiconductor company."
Infineon's customers pair the MEMS die with the appropriate ASIC then wire bond the two together into the same package. Critical to this operation is the acoustic atmosphere inside the package, which need to allow the free flow of air in and out and yet need to apply just the right amount of back pressure to the microphone diaphragm to achieve the desired frequency spectrum and linearity.
"We know how to make integrated circuits, but our customers know how to create the proper acoustic packaging," Helm told EE Times.