Semiconductor components are expected to perform reliably over the lifetime of the product. Choosing devices with the highest reliability ratings limits the likelihood of faulty components causing product failure in the field. SiTime provides oscillators that meet this goal, with zero MEMS field failures over 250 million units (as of January 2015). Zero field failures is impressive, but engineers want assurance that parts have been adequately tested for reliability. The key metric for gauging reliability of semiconductor components is mean time between failure, or MTBF. The higher the MTBF, the longer the expected lifetime of the device and therefore the more reliable the device. This application note describes the testing process and calculations of predicted MTBF for SiTime MEMS oscillators.