Advantage and Disadvantage: Lead-free HASL PCB

What is HASL PCB?

HASL PCB refers to Hot Air Solder Level Printed Circuits Board. HASL refers to the PCB immersed in molten solder, and then through the strong hot air will be the surface and the hole in the excess solder blowing off, to get a bright coating. One is to use lead-tin alloy, leaded tin spray furnace temperature of about 240 degrees, the other is to use pure tin, because lead is more harmful to the human body, many European countries have banned the use of leaded tin, so it is now popular to use pure tin or called lead-free tin spray. Lead-free HASL PCB, lead-free furnace temperature of up to 300 degrees, coupled with the operating environment of high temperature and high corrosion, the PCB is extremely harmful, the advantages of good solderability, reliability is excellent.

Differences between HASL and LF-HASL.
(1) Lead content: HASL can reach 37. LF-HASL is less than 0.5.
(2) Surface brightness: HASL is better than LF-HASL.
(3) Soldering Activity: Leaded tin wire is relatively better than lead-free tin wire.
(4) Solderability: LF-HASL is better than HASL, the reason is that LF-HASL tin melting point is higher.

Advantage and Disadcantage of LF-HASL.
-Lowest cost PCB surface process that maintains solderability throughout the manufacturing process with no negative impact on ICT.
-Commonly uses leaded processes, which are now restricted and will eventually be eliminated by 2007. For fine pin spacing (<0.64mm) can lead to soldering
-Unsuitable for soldering fine-gap pins and components that are too small, as the surface flatness of the tin-sprayed boards is poor and they are prone to tin beads during subsequent assembly, which are more likely to cause short circuits for fine-gap pin components. Bridging and thickness issues. Poor surface flatness can lead to homogeneity problems in the assembly process. often used ENIG,ENEPIG,LF-HASL,Immersion Silver,…

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