The Electroless Nickel Immersion Gold (ENIG) surface finish is an extremely flat finish for the copper pads. For fine-pitch components, such as 0.5mm pitch and smaller BGAs, and other ICs, it is important to have a planar pad surface to ensure even contact between all the contacts and the solder paste. HASL surface finishes consist of a thin layer of solder which leaves an uneven, rounded meniscus on the edge of the pads, leading to solder defects for fine pitch parts.
Defects as a result of poor pad planarity are difficult to detect and repair, and may result in poor yield. We reserve the right to refuse orders if the risk is too high. Therefore, for Seeed Fusion PCB Assembly orders, we recommend spending a little extra for the ENIG surface finish.
Other than cost, there are very few cases where HASL would be preferred over ENIG. Some exceptions include if your boards are entirely through-hole boards or the SMD parts are quite large. In which case, ENIG would not be necessary. Please note that additional fees may be charged if the surface area of ENIG required is significant, i.e. above 25% of the total board surface area.
Thank you very much for your understanding. Please get in touch
with us if you have any questions,
Seeed Fusion support team
Last Modified 2020/11/20