HASL frente a ENIG: cómo elegir un acabado superficial para la placa de circuito impreso de tu montaje

A surface finish is more than the visible color of a PCB pad. It protects exposed copper and provides the surface used during soldering or electrical contact. The useful question is not which finish looks more premium, but which one fits the components, assembly process and intended use.

Understand the basic difference

HASL means hot-air solder leveling: exposed pads receive a solder coating. Leaded and lead-free HASL are different selections, so write the requirement explicitly. ENIG means electroless nickel immersion gold, a finish consisting of nickel with a thin gold layer above it. Selecting a lead-free board finish alone does not establish the compliance of an entire assembled product.

Consider the component land pattern

HASL can leave a less even pad surface than ENIG. Pad flatness can matter when assembling small or fine-pitch components. ENIG is commonly considered where a flatter finish is useful, but that does not make it the correct choice for every board. Review the package and assembler’s recommendations alongside the available fabrication options.

Separate solder pads from mating contacts

A connector contact that will be repeatedly inserted and removed has a different job from a pad that will be soldered once. ENIG is not the same process as electroplated hard gold for wear-resistant edge contacts. If the board has gold fingers or another contact requirement, state that separately instead of assuming a general ENIG selection covers it.

Compare quotes using an unchanged specification

Save the same dimensions, quantity, layer count and copper requirements before comparing finish options. Otherwise, a price difference may come from an unrelated selection. Keep a short decision note such as “flatness requirement to be reviewed for this package,” rather than treating an unreviewed default as an engineering decision.

• Identify the assembly method and relevant component packages.
• State whether any contacts require a separate treatment.
• Ask about packaging and storage expectations for the planned build schedule.
• Record the accepted finish in the fabrication drawing and order settings.

Make the selection visible at handoff

If the BOM or layout changes after quotation, check whether the finish choice still fits the new component set. Tell the fabrication and assembly teams about the revision together. A finish decision recorded only in an email can be missed when a replacement archive is uploaded.

Referencias técnicas: Eurocircuits: the purpose of surface finishes; surface-finish characteristics. These references explain general processes; they are not DIYIPCB price or availability commitments.