The two most common solder coatings are Hot Air Solder Leveling (HASL) using tin-lead solder alloys and Lead-free HASL using tin-based lead-free alloys. This article provides a detailed comparison between traditional leaded HASL and modern lead-free HASL processes.

HASL or HAL (for hot air (solder) leveling) is a type of finish used on printed circuit boards (PCBs). The PCB is typically dipped into a bath of molten solder so that all exposed copper surfaces are covered by solder.

This guide has provided differences between HASL and lead-free HASL as they provide respective physical and mechanical strengths in their application. Also, while HASL offers cost-effective benefits to PCB surface finishes, it is not RoHS compliant.

Jan 15, 2020 · Hot Air Solder Leveling (HASL) is a widely used surface finish in PCB manufacturing. It involves coating the exposed copper surfaces of a PCB with a layer of solder to protect them from oxidation and facilitate the soldering process during assembly.

Lead-free HASL uses lead-free alloys and offers a smooth, even, and high-quality surface finish. This finish is highly solderable and environment-friendly. Coating thickness is more uniform and thus eliminates coplanarity issues caused by the HASL process (on BGA , CSP pads, etc.).

Aug 29, 2023 · Traditional HASL uses a tin-lead solder alloy containing about 63% tin and 37% lead. Lead-free HASL substitutes lead for metals like silver, copper, bismuth, or antimony while maintaining a high tin content above 95%.

Feb 24, 2025 · Lead-free HASL is a modern alternative to traditional HASL, using lead-free solder alloys such as tin-silver-copper (SAC) or other similar mixtures to coat the PCB. This finish was developed...

When choosing between Hot Air Solder Leveling (HASL) and Lead-Free HASL for your PCB surface finish, several key factors should be considered based on the specific requirements of your project. HASL traditionally uses a tin-lead (SnPb) alloy, which is cost-effective and offers good solderability.

Mar 17, 2025 · HASL Lead-Free is a surface finish process where a layer of solder is applied to the PCB surface to create a conductive surface for component soldering. In the case of lead-free HASL, the solder used is typically a mixture of tin and silver or other lead-free alloys, which makes it compliant with modern environmental regulations, like RoHS.

Jun 28, 2024 · The transition to HASL-LF, which is Lead-Free, is largely fueled by environmental considerations and standards like the RoHS directive. Lead-free HASL variants utilize materials like tin-copper alloy, which are more eco-friendly and safer for end-users.