Analysis of the reasons for the unsmoothness after lead-free solder paste soldering

inSolder pasteIn the process of surface mount technology (SMT) processing and soldering, you may find that the circuit board after soldering is not as smooth as you imagined, but rather granular. What could be the reason for this? Today, Shenzhen JJY Solder Paste Manufacturer will explain to everyone:

The main reasons for the roughness after lead-free solder paste soldering are as follows:

1, If the solder paste is preheated for too long, some of its components will evaporate, and the solder paste will oxidize during this process. Using such solder paste will result in the phenomenon of particles after soldering. This situation can generally be solved by shortening the preheating time. Reducing the preheating time usually does not exceed2Minutes.

2If the components are not clean or there are residues on the surface of the circuit board, the solder paste cannot directly contact the circuit board and protrudes. After soldering, it will also produce an uneven phenomenon. In this case, at the very beginning, it is necessary to inspect the components and circuit boards to ensure that the surfaces are clear and clean before starting to use them.

3If the solder paste dries, the soldering effect will also be poor and it will be granular. Therefore, it is necessary to ensure the wettability of the solder paste.

4The issue of flux.

5Lead-free solder paste should have good wettability. Under normal circumstances, the time that solder stays above the liquid phase line during reflow soldering is30~90The time during wave soldering when the pins to be soldered and the substrate surface of the circuit board come into contact with the wave peak of the solder solution is seconds4After using lead-free solder for about a second, it is necessary to ensure that the solder can exhibit good wetting performance within the above time range to guarantee a high-quality welding effect.

6The electrical conductivity and thermal conductivity of the solder paste after soldering should both be consistent63/37Tin-lead alloy solder is close to each other.

7.The tensile strength, toughness, ductility and creep resistance of lead-free solder paste solder joints should all be comparable to those of tin-lead alloys.

As a well-established solder paste manufacturer with a history of sixteen years, JJY has been dedicated to the research and development as well as production of solder paste for many years. Our solder paste is of stable quality, without solder disconnection, false soldering or monument erection. Wuxi beads, no residue, bright and full solder joints, firm solder joints, and excellent electrical conductivity. If you have any needs, please feel free to contact us.