Why are some PCB circuit board pads not easy to be tinned? Here, FASTPCBA PCB and PCBA Manufacturer will analyze the possible reasons for you.

The first reason is: we need to consider whether it is a customer design problem, and we need to check whether there is a connection between the pad and the copper sheet that will cause insufficient heating of the pad.

The second reason is: whether there is a problem with customer operation. If the welding method is not correct, it will affect the insufficient heating power, insufficient temperature, and insufficient contact time.

The third reason is: the problem of improper storage.

1. Under normal circumstances, the sprayed tin surface will be completely oxidized in about a week or even shorter.

2. OSP surface treatment process can be stored for about 3 months

3. Long-term preservation of immersion gold plate

The fourth 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 fifth 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 sixth 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.

The above is an analysis of the reasons why PCB pads are not easy to be tinned. I hope to help you. If you need to know more about PCB production and SMT knowledge, please visit the official website of FASTPCBA.