Microstrip signal integrity enhancement by using low-loss solder mask

Microstrip design in printed circuit board (PCB) suffers potential high insertion loss or higher crosstalk, compared to stripline. The loss of microstrip has been a key limiting factor for high speed application. In this paper, a new type of solder mask material with low dissipation factor (DF) is proposed to apply in the microstrip design, instead of the regular solder mask. The proposed approach by using low loss solder mask can improve the microstrip signal integrity more than 10%. Designers can use the outer layers with the lower loss to have more design flexibility.