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Comparison of PCB surface finishes including ENIG and HASL on UK-manufactured circuit boards

 

Introduction: why PCB surface finishes matter

When it comes to printed circuit board (PCB) manufacturing, choosing the right PCB surface finish is a critical decision. The finish provides a protective layer over exposed copper pads and plays a major role in solderability, reliability, cost, and long-term performance.

At Tate Circuits — a trusted UK PCB manufacturer with Shenzhen production — we are often asked:
👉 “Should I choose ENIG or HASL?”
👉 “What are the pros and cons of different PCB finishes?”
👉 “Which PCB finishes meet RoHS compliance?”

This guide explains the most common PCB finishes, their applications, advantages, and limitations, so you can select the right option for your next design.

You can also see our full PCB capabilities here.

What is a PCB surface finish?

A PCB surface finish is a coating applied to the copper pads of a printed circuit board. Without a finish, copper oxidises quickly and becomes difficult to solder. The finish ensures:

  • Reliable solder joints during assembly

  • Protection against oxidation and corrosion

  • Compatibility with fine-pitch components

  • Long-term board reliability

Common PCB finishes explained

1. HASL (Hot Air Solder Leveling)

Description: Copper pads are coated with molten solder and levelled using hot air knives. Available in leaded and lead-free (RoHS compliant) versions.

Pros:

  • Cost-effective and widely available

  • Strong, durable solder joints

  • Long shelf life

Cons:

  • Uneven surface (not ideal for fine-pitch or BGA components)

  • Higher thermal stress during processing

  • Less suitable for high-density or HDI PCBs

Typical use cases:
Consumer electronics, industrial boards, lower-density designs where cost control is important.

2. ENIG (Electroless Nickel Immersion Gold)

Description: A thin layer of gold over a barrier layer of nickel, deposited chemically.

Pros:

  • Flat, smooth surface (perfect for fine-pitch and BGAs)

  • Excellent oxidation resistance

  • RoHS compliant (lead-free)

  • Superior shelf life

Cons:

  • Higher cost than HASL

  • Risk of “black pad” if not controlled properly

Typical use cases:
High-reliability products, aerospace, medical, automotive, and consumer devices with fine-pitch components.

3. Immersion Tin

Description: A thin tin coating deposited directly onto copper.

Pros:

  • Flat surface finish

  • Lead-free / RoHS compliant

  • Good for press-fit applications

Cons:

  • Limited shelf life (oxidation risk)

  • Tin whisker risk if not controlled

  • Sensitive to handling

Typical use cases:
Automotive, telecoms, and applications with press-fit connectors.

4. Immersion Silver

Description: Silver coating applied over copper pads.

Pros:

  • Excellent conductivity

  • Flat, solderable surface

  • Cost-effective alternative to ENIG

  • RoHS compliant

Cons:

  • Tarnishes if improperly stored

  • Sensitive to environment (sulphur contamination risk)

Typical use cases:
High-speed signal PCBs, RF applications, telecoms.

5. OSP (Organic Solderability Preservative)

Description: Transparent, water-based organic coating applied to copper.

Pros:

  • Lowest-cost lead-free finish

  • Flat surface, suitable for fine-pitch

  • RoHS compliant

Cons:

  • Limited shelf life

  • Easily damaged during handling

  • Not ideal for multiple reflows

Typical use cases:
Consumer electronics, high-volume production, single-assembly PCBs.

ENIG vs HASL: which should you choose?

This is one of the most common questions from PCB buyers.

  • Choose HASL if you want the lowest-cost option, durability, and are working with larger components.

  • Choose ENIG if you need a flat surface, high reliability, fine-pitch components, or long shelf life.

➡️ Tip: Many customers ask us for pricing on both ENIG and HASL before making a decision.

Compliance: lead-free and RoHS

  • Lead-free HASL, ENIG, Immersion Tin, Immersion Silver, and OSP are all RoHS compliant.

  • Traditional HASL (SnPb) is still used in some industries but is not RoHS compliant.

At Tate Circuits, we supply RoHS-compliant PCB finishes as standard.

How to choose the right PCB finish

When selecting a finish, consider:

Component type and density (e.g., fine-pitch BGAs = ENIG or OSP)

Shelf life requirements

Budget

Environmental compliance

Industry reliability standards

Our engineers are here to advise you on the best option for your project.

FAQs about PCB finishes

Q: Is HASL still used in modern PCB manufacturing?
A: Yes, lead-free HASL is still very common for cost-sensitive applications.

Q: Which PCB finish lasts the longest?
A: ENIG generally offers the best shelf life.

Q: What’s the cheapest PCB finish?
A: OSP is the lowest-cost RoHS-compliant finish.

Q: Can I request both ENIG and HASL pricing?
A: Absolutely — many customers compare both options before placing an order.

Why choose Tate Circuits as your PCB supplier?

  • Over 50 years as a UK PCB manufacturer

  • ISO-certified, UL-approved, Shenzhen factory pricing with UK-based support

  • Fast turnaround, flexible invoicing (“order now, pay on delivery”)

  • Technical support from UK engineers

📩 Need a price comparison?

Ask us for both ENIG and HASL pricing on your next design.
Request a fast PCB quote ›