1、 Reason for operation

The welding method is not suitable for heating, power, temperature, and contact time

2、 Design reasons

The connection method between the solder pad and the copper foil may result in insufficient heating of the solder pad

3、 Reasons for soldering flux

1. Lack of activity, unable to completely remove oxide substances from PCB pads or SMD solder joints

2. The amount of solder paste at the solder joint is insufficient, and the wetting performance of the flux in the solder paste is poor

3. Part of the solder joints are not fully soldered, perhaps due to insufficient mixing of flux and solder powder before use

4、 Reasons for improper storage

1. Under normal circumstances, the tin sprayed surface will completely oxidize within about a week or even shorter

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

3. Long term storage of sunken gold plates

5、 Reasons for board factory handling

There is oily substance on the solder pad that has not been removed, and the solder pad surface is oxidized without treatment before leaving the factory

6、 Reasons for reflow soldering

Excessive preheating time or high preheating temperature leads to the failure of flux activity; The temperature is too low or the speed is too fast, and the tin has not melted.

Article source: PCB manufacturerhttp://www.yonghongpcb.com/