Application of temporary solder mask in SMT of high frequency circuit boards

A high frequency PCB (printed circuit board) can not be coated with solder mask, because solder mask on a PCB, acting as a kind of dielectric, greatly affects the electronic characteristics of high frequency circuits. But, the soldering of SMD (surface mounted devices) on a PCB with no solder mask brings on many problems during assembly, such as lack of solder in solder joints, components soldered onto the PCB which are skew, are away from solder pads, or stand up like tombstones. Now, we can use a temporary solder mask to solve all these problems.