How to prevent blowholes caused by welding in PCBA processing

The pores generated by soldering during PCBA processing, that is, the bubbles we often say, are generally generated during reflow and wave soldering. So how to improve the problem of PCBA welding pores?

1.Baking

Bake PCBs and components exposed to the air for a long time to prevent moisture.

2.Control of solder paste

If the solder paste contains water, it is easy to generate pores and beads. First select a good quality solder paste. The temperature of the solder paste and the stirring are strictly implemented according to the operation. The exposure time of the solder paste to the air is as short as possible. After the solder paste is printed, reflow soldering should be performed in time.

3. Workshop humidity control

Plan to monitor the humidity of the workshop and control it between 40-60%.

4. Set a reasonable furnace temperature curve

The furnace temperature test is performed twice a day to optimize the furnace temperature curve, and the heating rate cannot be too fast.

5.Flux spraying

In wave soldering, the spraying amount of flux should not be too much, and the spraying is reasonable.

6.Optimize the furnace temperature curve

The temperature in the preheating zone must meet the requirements, not too low, so that the flux can be fully volatilized, and the speed of the furnace must not be too fast.

There may be many factors affecting PCBA soldering bubbles, which can be analyzed in terms of PCB design, PCB humidity, furnace temperature, flux (spray size), chain speed, tin wave height, solder composition, etc., which need to be debugged multiple times. May lead to better processes.