Choosing the right surface finish is as important as choosing the right PCB manufacturing and assembly companies. A wrong surface finish can impact the reliability, durability, and entire assembly process. This is because the surface finish protects the prototype PCB assembly Oregon, contact pads, and soldering pads from contamination and oxidation. For this reason, you can consider certain types of surface finish.
HASL
HASL is hot air solder leveling, and it’s the most affordable surface finish and is easy to find. With HASL, the PCB is dipped in the molten solder mixture and is leveled with the hot air knife. This is a suitable option when the PCB has bigger SMT components. On the other hand, if your PCB assembly has smaller than 0805 SMT components, it’s suggested to avoid it. In most cases, Tin-Lead solder is used, which means it’s not RoHS compliant.
Lead-Free HASL
Lead-free HASL is similar to regular HASL, but it doesn’t have Tin-Lead solder. In its place, Tin-Nickel, Tin-Copper-Nickel, or Tin-Copper might be used. This makes it affordable as well as compliant with RoHS. It promises high-end solderability and allows bigger processing windows. In addition, it has multiple thermal excursions, but it also requires high processing temperatures, ranging from 260-degrees to 270-degrees Celsius.
Immersion Tin
With immersion tin, a flat, thin metal layer is applied on the copper traces, making it suitable for small components. The best thing about immersion tin is the affordable price, but it cannot be used with copper. Immersion tin promises a press-fit finish and offers reliable solderability. If you choose immersion tin for prototype PCB assembly Oregon, remember that it needs several thermal excursions.
