PCB Surface Finish Types, Process, and Comparison!

There are different verities of surface treatment for (PCB) printed circuit board, PCB proofing staff as indicated by the board’s execution and necessities to pick, the accompanying basic investigation of the PCB surface treatment of different stresses, for reference!

1. Hot air leveling (Known as HASL)

HASL is the most well-known utilized as a part of PCB handling. Presently HASL is partitioned into two sorts processing, spray tin with lead and spray tin with lead-free.

Advantage of HASL:

• Longer storage time
• When PCB is finished, the pads is totally wet (totally covered with tin before welding)
• Appropriate for lead-free soldering
• Mature
• Low price
• Can be in visual investigation and electrical estimation

Weakness of HASL:

• Not reasonable for line binding; because of surface roughness issues, there are limitations in the SMT; can’t utilized for touch switch.
• When HASL, the copper will break up and the board is subjected to a high temperature.
• Especially for thick or thin board, HASL is limited; the production processing is not Appropriate.

2. OSP (organic protective film)

OSP is a water-based, organic surface complete that is typically utilized for copper pads. It selectively bonds to copper and secure the copper pad before soldering.

Advantages of OSP:

• Simple process, the surface is exceptionally smooth, appropriate for lead-free soldering and SMT.
• Easy to revamp, simple to work and appropriate for horizontal production line.
• One board can have diverse surface complete, (for example, OSP + ENIG)
• Low price and environmental friendly.

Weaknesses of OSP:

• Cannot take too often in reflow soldering (After soldering times, circumstances, the film will be decimated, typically can be welded 2 times)
• Not appropriate for crimping technology, line binding.
• It isn’t advantageous for visual review and electrical measurement.
• Requiring N2 gas insurance while SMT.
• High necessity for Storage conditions.

3. Immersion silver

Immersion silver is a superior surface treatment process.

Advantages of chemical silver:

• Simple procedure, appropriate for lead-free soldering, SMT.
• The surface is very level
• Appropriate for very fine traces.
• Low price.

Weaknesses of Immersion Sliver:

• High need for Storage conditions. Simple to be polluted.
• May have some welding quality issues (micro-hole problem).
• Prone to electro relocation wonders and the copper under solder mask will meet will meet galvanic consumption marvel.
• Hard for electric test

4. Immersion Tin

Immersion Tin is the pronest to copper and tin substitution response.

Immersion Tin Advantages:

• Appropriate for horizontal production line.
• Appropriate for fine trace processing, appropriate for lead-free soldering, particularly for crimping technology.
• Very great flatness, appropriate for SMT.

Weaknesses:

• Needed awesome storage conditions would be wise to not to capacity for over a half year in order to control the tin whisker to grow.
• Not appropriate for contact switch.
• High needs for solder mask processing or solder mask will be off.
• When multiple welding, we require N2 gas security.
• Hard for electric test.

5. Immersion Gold (ENIG)

Nickel layer is nickel-phosphorus combination layer, as indicated by the phosphorus content is isolated into high phosphorus nickel and phosphorus nickel. The application isn’t the same; here we don’t present the distinction.

Advantages of Nickel:

• Appropriate for lead-free soldering.
• The surface is very flat, Appropriate for SMT.
• Through-hole can additionally be plated with nickel gold.
• Storage for longer time, stockpiling conditions are not brutal.
• Appropriate for electric test.
• Appropriate for contact switch.
• Appropriate for aluminum binding, Appropriate for high thick panel, can hold more natural attacks.

6. Hard Gold

Electroplating nickel gold is separated into “hard gold” and “soft gold”, hard gold, (for example, gold and cobalt amalgam) generally utilized as a part of the gold finger (association plan), soft gold is pure gold. Hard gold is frequently utilized as a part of the IC transporter board, (for example, PBGA), predominantly for gold and copper wire authoritative. Gold finger region need to add extra conductive follow to plating.

Advantages of Hard Gold:

• Longer storage time> a year.
• Appropriate for contact switch and gold wire binding.
• Appropriate for electric test

Weaknesses of Hard Gold:

• Higher price, gold is thicker.
• Electroplating gold finger will require an extra conductive trace.
• Because of the thickness of the gold is not coherence, so hard gold isn’t generally utilized as a part of welding.
• Plating surface consistency issue.
• Plated nickel gold does not wrap the edge of the line.
• Not Appropriate for aluminum trace binding.

7. Nickel palladium (ENEPIG)

Nickel palladium is currently starting to be utilized as a part of PCB; ENEPIG is utilized to be implicated in the semiconductor. Appropriate for gold and aluminum trace binding.

Advantages:

• Application in the IC carrier board, Appropriate for gold wire binding, aluminum binding. Appropriate for lead-free soldering.
• Compared with ENIG, there is no nickel consumption (black plate) issue; cost is less expensive than ENIG and nickel.
• Long storage time.
• Appropriate for variety of surface treatment forms and on board.

Weaknesses:

• Complex process. Difficult to control.
• ENEPIG is another technique and not develop enough.

If you need to know how the surface complete influences the value, you can contact to PCB prototype service. It will calculate the estimated cost automatically.