One of the most common tests offered by companies who perform semiconductor testing services is Moisture Sensitivity Level or MSL. MSL testing involves exposing a set of packaged devices to various levels of heat and humidity. The MSL testing conditions are relatively harsh compared to normal storage or operating conditions; as a result, defects like cracking or delamination may appear much more quickly than typically expected. After being subjected to these conditions, the devices are examined for any signs of damage, usually with an acoustic microscope (which is preferred for its ability to image all the internal layers of a package, not just the exterior surface). Assuming that no defects are found, the devices are assigned an MSL rating depending on the severity of conditions they were exposed to.
Similar to MSL, Highly Accelerated Life Tests (or HALTs) subject a device to all manner of external stresses – rapid temperature changes, mechanical shocks and vibrations, power cycling, even ionizing radiation in some cases – in an attempt to cause a failure. By taking a small number of devices and subjecting them to stresses far beyond what they would see during normal operation, the inherent weaknesses of a device or process can be identified and improved upon. Due to the elaborate nature of the tests, many companies choose to perform HALT in-house instead of outsourcing them to a lab providing semiconductor testing services; however, they may still enlist an outside source for root cause analysis of a device after it has failed during HALT.
Ultimately, semiconductor testing services are absolutely crucial to the production of modern electronics. Whether a device will be blasted into space on a satellite or installed in the living room of a tiny apartment, reliability and dependability are paramount; without proper testing and analysis, acceptable device lifespans may very well be out of reach.