Thermal management of a wide range of electronics is increasingly important. In order to ensure high-quality, many electronic PC boards are built using solder paste that is reflowed in a heated tunnel (reflow oven). Many PCBs that will be subjected to various temperature and environmental conditions must be conformally coated; this is a spray process that is then heated to ensure the coating cures properly. The most sophisticated semiconductor devices (chips) are moisture sensitive and must be “baked-out” in a slow, lower temperature oven before being soldered onto a PCB. If the moisture inside the device is not removed, it will “boil” and cause internal damage to the device. Thermal management is a key process to manage in order to avoid this issue. Another important aspect of thermal management is the requirement to environmentally test finished PCB assemblies to insure that they can withstand the wide range of temperature swings that the end product will be subject to in use.
Can you imagine a circuit board sitting in the hot Arizona sun, slowly baking at 125 degrees for days on end? Or what about a circuit board that is part of an underwater drill and sensor, constantly being subject to intense pressure? Most military electronics are subject to wide temperature swings in use and very significant shock and vibration requirements - all of these devices and assemblies must undergo environmental testing to validate that the design and manufacturing processes are robust enough for successful deployment. Many thermal test chambers can simulate wide temperature swings (from -40 C to + 180 C) and can also vary the humidity to verify performance in a wide range of humidity conditions. Thermal cycling is the process of moving through hot and cold states, to stress the device under test to identify possible failure.