Surface Texture on Solder Joints after Reflow
Seeing surface effects when using lead-free solder is not an unusual occurrence. There are many factors that could be causing texture on the solder joints after reflow.
The following are several of the more common factors that could be contributing to this defect:
- Thermal profile used, peak temperature and cool down rate
- Metal finishes on the parts that were soldered, dissolution occurs which can impact color
- Reflow atmosphere
- Physical or chemical properties of the flux, some fluxes react more with the solder surface than others
- Flow properties of the flux during the reflow process, some fluxes flow more rapidly than others, giving extended exposure to oxygen
- Excessive oxidation of the parts to be soldered
- Shelf life of the paste or how the paste was handled prior to use