PCB Surface Finish
PCB surface finish varies in price, availability, shelf life, reliability and assembly processing. It is so common for every PCB designer, engineer, hobbyist, etc., but do you really know it well? In this article, EPCB will outline each finish’s feature.
Hot Air Solder Leveling or HASL: If not take lead-free into consideration, then HASL is a very cost-effective and reliable surface finish used in the fabrication of lower technology PCBs. However, the HASL process may add stress to high layer circuit boards, and that can cause long-term reliability issues.
Electroless Nickel/ Immersion Gold or ENIG: The ENIG surface finish has ever been the best pitch surface and lead-free option for manufacturers around the world. Excellent shelf life and long-term experience are its typical benefits. However, its disadvantages are very obvious; they are limited availability, higher cost and two-part process.
Immersion Silver: The immersion silver process has been widely well received among PCB manufacturers in the world as a lead-free surface finish of choice. Though so far ENIG has had a larger market share, over the past 12 months more immersion silver process lines have been installed in PCB manufacturers than any other finish. The typical benefits of immersion silver are that is has a controlled thickness of 5-12 micro inches and a shelf life of at least 12 months.
Organic Solderability Preservatives or OSP: OSP is a method for coating of printed circuit boards, and has been around since 1970's. The OSP uses simple technology with low cost, and that makes it more and more popular among PCB industry. OSP has a variety of advantages, for example, it can be used in a low temperature, its cost is lower than use HASL, less energy is needed during processing, etc. Besides, they can handle multiple heat cycles and have a one year shelf life.