Converting AC voltage to higher or lower amounts in semiconductors and other applications requires that power supplies use transformers. The solution is a simple one, yet there are four common issues power supply transformers face that can inhibit reliability.
Far and away, this is the number one reason why power supply transformers are susceptible to failure. A wide range of variation occurs from builder to builder which can be problematic in semiconductor packages, like wire kinking or not having enough safety tape applied. To level the playing field, using traces for windings on a PCB is often implemented but the measure is aimed at minimizing failure risk, not necessarily preventing it.
The highly specialized skills and training required to properly use magnetics is still evolving in the world of semiconductors and, as such, it’s not uncommon for the saturation current and core-winding temperature to be misaligned -- the former is generally too low, and the latter is too high.
Added weight, added stress
Separate from the physical workings of a power supply transformer is the added weight -- and added stress -- it places on the PCB. Coupled with shock and vibration, transformer weight can cause board bending and cracking if the load is not properly supported and, in some cases, the transformer can detach from the PCB altogether.
High thermal mass
Oven profiles for assembly can be problematic because the thermal mass of transformers is exceptionally high, especially in comparison to other components within the semiconductor package. Long oven dwell times are required to ensure the part is at a temperature adequate for a decent solder, but damage can occur to the other components if not carefully monitored.
Vigilance is required in balancing the needs and risks of using power supply transformers on PCBs. Semiconductor packaging engineers can ensure reliability in the design phase by introducing Physics of Failure (PoF) into the design process with a powerful tool like Sherlock Automated Design Analysis™ software. Learn more in Best Practices in Implementing Physics of Failure into the Design Process. Click the button below to access this informative webinar.