1. Solder peeling

After the PCB leaving the solder, the connecting parts temperature cool to room temperature. At this stage, the curing heat diffusion to solder area, prompting the joints as well as all the parts near the temperature increases.

This movement has brought to the surface of the solder joint considerable pressure, but at this stage is still strong joints. Therefore, this pressure may cause the pads float away.

2.SolderTrailing

These residues are generally due to solder melting caused the collapse.

Use the right amount of flux to the nozzle area can be cleared completely covered tailing multimodal nozzle next.

Experiments show that only the amount of solder temperature and flux of these two parameters have a significant impact on the smearing.

Use SnPB, solder temperature can be reduced to 260 ?. After lowering the temperature enough to complete the through-hole filling.

3.Solder bridges

At this time, the solder cools, solidification, forming bridging. Horizontal welding can reduce the risk of instability in the solder flow.

Unstable solder flow. Lead-free solder nozzle deviates along pin flow trends

Pin shorter, smaller pad spacing between PIN feet wide can reduce the risk of some form of bridging.

4.Solder balls

Solder ball is mainly due to high temperatures and become more viscous solder resist produced. In addition, more flux than other substances produced solder balls. In a dual in-line package soldering process, solder balls usually appear between individual PIN foot

5.Copper pad dissolved

On the selective soldering peak flow of solder joints formed contact more frequently (robot speed 1mm / sec or slower), the higher soldering temperature (> 300 oC), the greater the risk.

Select the appropriate parameter, selective soldering can be successfully used. If necessary, it can be coated as a problem more elements each infiltration flux, soaked longer without other elements around because the temperature is too high and damage.