HASL, ENIG or OSP: which PCB surface finish for prototypes

The short answer

The surface finish is the thin metal or organic layer that protects the exposed copper pads until you solder. On the order form it is one dropdown. In practice it decides how flat your pads are, how long the bare boards can sit in a drawer, and whether a fine-pitch part will solder cleanly.

For a typical prototype with through-hole parts and ordinary SMD packages, lead-free HASL is the cheap, forgiving default. If the board has a BGA, fine-pitch ICs or a very thin substrate, pay for ENIG. If you will assemble within a few months and reflow only once or twice, OSP gives you flat pads at no extra charge at JLCPCB. The rest of this article gives the numbers behind that advice, and shows where the fabs disagree with each other.

HASL: leaded and lead-free

Hot air solder leveling dips the board in molten solder and blows off the excess with hot air. The result is a solder coating on every pad. JLCPCB's surface finish page lists the coating thickness as roughly 1 to 40 micrometers. That spread is the problem: the surface is domed and uneven, and JLCPCB rates its planarity as poor for BGAs and fine-pitch components.

The leaded version can contain up to 37% lead and is not RoHS compliant. The lead-free version is limited to 0.5% lead. Lead-free HASL runs at higher processing temperatures, which JLCPCB says puts more thermal stress on the board and makes it inconvenient for thin PCBs. PCBWay gives the melting points as 183 °C for tin-lead and 228 °C for lead-free solder.

Eurocircuits describes lead-free HAL as the finish with the highest level of solderability and the lowest cost. It also lists the limits: small via holes, high aspect ratios and fine-pitch pads do not suit it, because the amount of solder varies from pad to pad.

ENIG: flat and long-lived, but pricier

ENIG is electroless nickel with an immersion gold flash on top. The nickel is the real solderable layer. The gold only keeps the nickel from oxidizing. JLCPCB gives the nickel thickness as about 3 to 6 micrometers and offers 1 or 2 microinches of gold. Its comparison table lists the gold at 0.05 to 0.1 micrometers.

The payoff is a very flat, uniform pad. JLCPCB recommends ENIG for BGAs, fine-pitch parts, high-density packages and 0.4 mm boards. Eurocircuits also points to key pads and wire bonding as good uses.

There are three costs.

• Price. Eurocircuits calls it the most expensive finish it offers, and JLCPCB notes that the cost follows the gold price.
• Black pad. Both fabs name black pad and related plating defects (skip plating, interface embrittlement) as ENIG risks. JLCPCB adds that proper process control mitigates black pad.
• Brittle joints. Eurocircuits explains that the solder joint forms against the nickel layer, and that this interface is considerably more brittle than the one on HAL. It does not recommend ENIG for boards exposed to shocks, bending or strong vibration.

OSP: flat, free, and on a clock

OSP is an organic film, a few tenths of a micrometer thick, that coats the copper. JLCPCB's comparison table gives 0.2 to 0.5 micrometers. The pads stay copper-flat, which suits dense layouts and BGAs, and JLCPCB charges nothing extra for it.

The limits are time and handling. JLCPCB's help page says OSP lasts up to three months under normal storage. Its comparison table says 3 to 6 months, and PCBWay says less than 6 months and describes that as poor. The fabs disagree on the exact figure, so treat three months as the safe planning number. PCBWay also notes that OSP is difficult to inspect and sensitive to handling.

OSP also does not like repeated heating. JLCPCB's help page says it withstands four soldering operations (two reflow and two wave). The same fab's comparison table lists 1 to 2 reflow cycles as the practical limit. A double-sided reflow board already uses two passes, so there is no room for a rework run on a board that has aged. OSP is also unsuitable for gold-finger connectors and castellated-hole boards, according to JLCPCB.

Side by side

Do not treat the thickness and shelf life columns as universal. JLCPCB's own help page gives 1 to 40 µm for HASL, while its comparison table gives 1 to 25 µm for the lead-free version. PCBWay lists shelf lives of 12 months for lead-free HASL and for ENIG. Ask your fab for its own figures if the board is going into stock.

How to choose for a prototype

Start from the parts on your board, not from the price list.

1. BGA, fine pitch or a 0.4 mm board: ENIG, or OSP if you can solder within weeks. Both give flat pads. HASL does not.
2. Through-hole and ordinary SMD, hand soldering, boards that may sit for months: lead-free HASL. It has the best solderability and the lowest price.
3. Boards that will be shaken or flexed: favor HASL over ENIG, following Eurocircuits' warning about the nickel interface.
4. Boards that will be sold or shipped in the EU: order a lead-free finish. JLCPCB lists leaded HASL as not RoHS compliant.
5. Gold fingers or castellated holes: not OSP. Eurocircuits adds that edge connectors use a separate hard gold plating, which cannot be applied elsewhere on the board.

Whatever you pick, a finish cannot fix bad data. Before you pay for the board, run through the files once more. Our article on common Gerber file errors lists what fabs reject most often, and the guide to checking Gerber files before ordering gives the full routine. You can open the ZIP in the PCB Tools Gerber viewer and look at pad shapes and solder mask openings before you commit.

Sources

All sources checked on 2 October 2026.

• JLCPCB, PCB surface finish
• JLCPCB, Comparing OSP plating with other PCB surface finishes
• JLCPCB, Comparing HASL and ENIG surface finishes for PCBs
• Eurocircuits, Selecting the right surface finish for your PCB
• PCBWay, PCB surface finish
• iConnect007, The Plating Forum: The IPC surface finish specifications

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