What is HASL with lead and why you may prefer it over ENIG

PCBs offered by HiFiOcean are finished in hot-air solder leveling (HASL) with leaded solder, are 1.6mm (0.062in) thick, have 1oz (35um) copper and a green solder mask. Why are these choices and not something else? The short answer is "to make boards easier to solder and to keep prices low without sacrificing the quality".

Hot-air solder leveling (HASL) leaded solder is a good and inexpensive option. Other major options are:

  1. HASL with lead-free solder. More difficult to solder by hand, as it has higher melting point and doesn't wet parts as well as leaded solder does. You probably don't want it unless you need to comply with RoHS or similar regulations.
  2. ENIG (electroless nickel immersion gold).  Looks great and never tarnishes due to the thin gold plating. Has a thicker layer of nickel underneath; some people (for example, Allen Wright, the late founder of Vacuum State) have said it increases distortion. The real benefit of ENIG is the better co-planarity of SMT pads, which is good for soldering high lead count, fine pitch SMT packages.
  3. Immersion Silver, which I like best, except it is expensive and degrades (oxidizes, tarnishes) quickly.

Board thickness is 1.6mm or 0.062inch (62 mils). The advantage of thicker (usually 2mm) material is its mechanical ruggedness. You may want 2mm if the board is large and holds heavy components, such as power transformers. Otherwise, 1.6mm is good.

Copper weight is 1oz (35um). Thicker copper, such as 2oz, may be useful if your board needs to handle heavy currents in narrow traces. Thick copper is more difficult to solder, as thicker traces take away more heat from the joint being soldered.

Green solder mask used to be the cheapest option, and it was chosen to keep prices low. Recently, however, the premium for other colors has been disappearing, so you will see more board colors here on HiFiOcean.

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