In SMT welding technology, many customers usually have requirements for the brightness of the solder joints. After all, the brightness of the solder joints will give us a bright feeling. In the process of patch processing and welding, there is no guarantee that the brightness of each solder joint can reach the sparkling degree. So what is the reason for the insufficient gloss of the solder joints in the patch processing? The following is the editor to Dongguan Some summaries after consulting the senior engineer of the film processing plant.
SMT chip processing
1. The tin powder in the solder paste has the appearance of oxidation.
2. The flux in the solder paste has its own matting additive.
3. The preheating temperature of reflow soldering is relatively low in SMD processing, and there are residues that are not easy to evaporate and remain on the surface of the solder joints.
4. There are rosin or resin residues on the appearance of the solder joints after soldering. This is often seen in actual operations. Especially when rosin-type solder paste is selected, although rosin-type flux and no-clean flux are more likely to cause soldering The spot is slightly bright, but the presence of its residues often affects this effect, especially in larger solder joints or IC foot parts; if it can be cleaned after soldering, the gloss of the solder joints should be improved.
5. Since there is no standard for the brightness of the solder joints, if the products after soldering without silver solder paste are compared with the products after soldering with silver solder paste, there will be some distance, which requires customers to choose solder paste Should clarify their solder joint requirements to the supplier.
