Where there is no solder mask covering the copper surface on the PCB, such as the solder pads, gold fingers, mechanical holes, etc. Without a protective coating, the copper surface is easily oxidized, which affects the solderability of the bare copper and components in the solderable area of the PCB.
Hot Air Solder Leveling (HASL)
Hot Air Solder Level (HASL), commonly known as tin spraying, is divided into lead-free tin spraying and lead-based tin spraying, and is the most commonly used and relatively inexpensive surface treatment process.
The shelf life of PCB can reach 12 months, with process temperature of 250℃ and surface treatment thickness ranging from 1-40um.
The soldering process involves immersing the PCB in molten solder (tin/lead) to cover the exposed copper surface of the PCB. When the PCB exits the molten solder, high-pressure hot air is blown through the surface with an air knife to smooth out the solder and remove excess solder.
WeChat
