The process requirements in the PCB production are very important, which directly determines the quality and positioning of a board. Such as HASL, gold plating, ENIG.
Due to the good quality of ENIG, the price is higher too. Many customers choose the most common HASL process.
Many people know the HASL process, but they don't know what the difference is between HASL and HASL-LF. Please refer to the difference as below:
1. On the surface, Lead-tin is brighter and lead-free tin (SAC) is dim.
2. Lead in HASL is harmful to humans, but lead-free not. The lead eutectic temperature is lower than lead-free, which depend on Lead-free alloy composition. For example, The eutectic of SNAGCU is 217 degrees, the soldering temperature is eutectic temperature plus 30 to 50 degrees. The lead eutectic is 183 degrees. The mechanical strength and brightness with lead is better than lead-free.
3. The Lead content in HASL-LF is not more than 0.5, while HASL has a lead of 37.
4. The lead will increase the activity of the tin wire during the welding process, so Lead wire is easier to use than lead-free wire. However, lead is toxic and not good for the human body. What is more, Lead-free tin will have a higher melting point than lead-tin, so the solder joint is much stronger.