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The main reasons of poor soldering in PCB assembly

2019-05-14


Everyone knows that the pads of PCB board is not easy to solder , which will affect the component chips, which indirectly causes the subsequent test to not work properly. Here are the reasons why the PCB pads are not easy to solder on? I hope that you can avoid these problems when you make and use them, and minimize losses.

1.We have to consider whether it is a customer design problem, need to check whether the connection between the pad and the copper will result in insufficient pad heating.

2.Is there a problem with the customer's operation? If the welding method is not correct, it will affect the heating power is not enough, the temperature is not enough, and the contact time is not enough.

3.The problem of improper storage for PCBs, Different surface finish of PCB have different shelf life, it’s recommended that PCBs need to be assembled during shelf life.

4.The problem of flux soldering.
a, Insufficient activity, failure to completely remove oxides from PCB pads or SMD soldering sites;
b. The amount of solder paste in the solder joint is not enough, and the soldering property of the solder paste is not good;
c. Parts of the solder joints are not full of tin, may not fully stir the flux and tin powder before use is not fully integrated.

5.Oily material on the pad is not removed, and the pad surface oxidation is untreated before leaving the PCB factory.

6.  The problem of reflow soldering. Too long a preheating time or too high a 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.




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