The Difference between All Surface Treatments of The Circuit Board And Their Respective Advantages

OSP (Organic Solderability Preservative)
Advantages:

Low cost: Simple process, material cost is only 1/5 of gold plating.

High flatness: Surface roughness <0.3μm, suitable for high-density SMT mounting.

Environmental friendliness Does not contain heavy metals, complies with RoHS standards.

Disadvantages:

Storage restrictions: Must be used within 24 hours after opening, longterm storage requires N₂ protection.

Detection difficulties: Due to insulation, electrical testing requires additional window processing.

Application scenarios: Consumer electronics (such as routers TV motherboards).

HASL (Hot Air Solder Leveling/Spray Solder)
Advantages:

High cost performance: 40% lower cost ENIG, suitable for mid-low end products.

Strong welding performance: solder layer thickness of 1-3μm, excellent wettability.
Disadvantages:

Poor flatness: surface undulation of ±15μm, not suitable for devices with pin pitch below 0.4mm.
Large thermal stress: high temperature (250℃) spray soldering may cause deformation of thin boards.

Applicable scenarios: power modules, industrial control equipment, etc with large solder pad design.

Electroless Nickel Immersion Gold (ENIG)
Advantages:

High reliability: Nickel layer (3-5μm) preventsation, and gold layer (0.05-0.1μm) ensures soldering, storage period > 12 months.

Fine applicability: Sup 0.2mm BGA and QFN packaging.

Disadvantages:

Black pad risk: Excessive oxidation of nickel layer leads to brittess of solder joints, with a bad rate of about 0.5%-2%.

High cost: Accounts for 8%-15% of the totalB cost.

Applicable scenarios: Mobile phone mainboards, automotive ECUs, etc., for high-frequency, high-density boards.

Chemical silver (sinking silver)
Advantages:

High frequency performance: signal loss is 30% lower than HASL, suitable 5G millimeter wave circuits.

Process flexibility: compatible with press-fit technology and fine lines (line width/pitch ≥ 0.1mm).
Disadvantages:

Micro-void problem: welding strength is reduced by 15%-20%, requiring N₂ protection welding.

Storage sensitivity: silver layer is prone to sulfuration and blackening, requiring vacuum packaging.

Applicable scenarios: RF modules, high-speed communication equipment.

Electroplated nickel gold
Advantages:

Abrasion resistance: The thickness of hard gold (gold cobalt alloy) can reach 1m, and the insertion and removal life >100,000 times.

Contact reliability: The impedance of the gold finger is <2mΩ, suitable for high-frequency connectors.

Disadvantages:

Extremely high cost: The cost of the gold layer accounts for 20%-3% of the total cost of the PCB.

Complex process: Additional design of conductive leads is required, and the yield is 5%-10% lower than of ENIG.

Applicable scenarios: Server memory modules, graphics card gold fingers

Soldering;
Advantages:

High compatibility: Perfect match with tin-based solders, wetting time <1 second.
Environmental protection: Lead-free process, in compliance with EU ELV directive.

Disadvantages:

Tin whisker risk: May grow tin whiskers high-temperature and high-humidity environments, need to add organic inhibitors.

Applicable scenarios: Home appliance control boards, low-end consumer electronics