Three reasons for manufacturer is difficult to tin the High frequency PCB

The first reason is: the problem of flux.

1. Insufficient activity to completely remove oxides on PCB pads or SMD soldering positions

2. The amount of solder paste in the solder joints is not enough, and the wetting performance of the flux in the solder paste is not good

3. The tin on some solder joints is not full, and the flux and tin powder may not be fully mixed before use;

The second reason is: the problem of the board factory. The oily substance on the pad has not been removed, and the pad surface has not been oxidized before leaving the factory

The third reason is: the problem of reflow soldering. Too long preheating time or too high preheating temperature causes the flux activity to fail; the temperature is too low, or the speed is too fast, and the tin does not melt.