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PCB Surface Finish Comparison
Compare features, costs, and applications of different PCB surface finishes.
Quick Comparison
| Finish | Cost | Shelf Life | Flatness | Fine Pitch | Lead-Free | Reworkable | Wire Bond |
|---|---|---|---|---|---|---|---|
| HASL (Leaded) | $ | 12+ months | Poor | ||||
| Lead-Free HASL | $ | 12+ months | Poor | ||||
| ENIG | $$$ | 12+ months | Excellent | ||||
| OSP | $ | 3-6 months | Excellent | ||||
| Immersion Silver | $$ | 6-12 months | Excellent | ||||
| Immersion Tin | $$ | 3-6 months | Excellent | ||||
| Hard Gold | $$$$ | 12+ months | Good |
Detailed Information
HASL (Leaded)
Hot Air Solder Leveling (Leaded)
Thickness:1-40 μm
Color:Silver/Bright
Pros
- Lowest cost
- Excellent solderability
- Long shelf life
- Easy rework
Cons
- Not lead-free
- Uneven surface
- Not suitable for fine pitch
- Thermal shock to board
Best For: Through-hole, large SMD pads, prototypes, cost-sensitive projects
Lead-Free HASL
Hot Air Solder Leveling (Lead-Free)
Thickness:1-40 μm
Color:Silver/Bright
Pros
- RoHS compliant
- Good solderability
- Long shelf life
- Low cost
Cons
- Uneven surface
- Higher process temperature
- Not for fine pitch
Best For: RoHS-compliant products, through-hole assemblies
ENIG
Electroless Nickel Immersion Gold
Thickness:3-6 μm Ni, 0.05-0.1 μm Au
Color:Gold
Pros
- Flat surface
- Excellent for fine pitch
- Wire bondable
- Long shelf life
- Good for press-fit
Cons
- Higher cost
- Black pad risk
- Nickel can affect RF performance
Best For: BGA, fine pitch, aluminum wire bonding, high-reliability products
OSP
Organic Solderability Preservative
Thickness:0.2-0.5 μm
Color:Copper (clear coating)
Pros
- Lowest cost
- Flat surface
- Environmentally friendly
- Good for fine pitch
Cons
- Short shelf life
- Not visible inspection friendly
- Limited reflow cycles
- Sensitive to handling
Best For: High volume production, fine pitch SMD, cost-sensitive with fast turnover
Immersion Silver
Immersion Silver (IAg)
Thickness:0.1-0.4 μm
Color:Silver
Pros
- Flat surface
- Good planarity
- Gold wire bondable
- Good RF performance
Cons
- Tarnishes easily
- Micro-voiding risk
- Requires careful handling
Best For: RF/Microwave, membrane switches, high-frequency applications
Immersion Tin
Immersion Tin (ISn)
Thickness:0.8-1.2 μm
Color:Matte Silver/Gray
Pros
- Flat surface
- Good for fine pitch
- Press-fit compatible
- Good solderability
Cons
- Tin whisker risk
- Shorter shelf life
- Sensitive to handling
Best For: Press-fit connectors, fine pitch components, automotive (with mitigation)
Hard Gold
Electrolytic Hard Gold
Thickness:0.5-2.5 μm Au
Color:Bright Gold
Pros
- Extreme durability
- Excellent for edge connectors
- Corrosion resistant
Cons
- Highest cost
- Not solderable
- Selective plating required
Best For: Edge connectors, contact pads, high-wear applications
How to Choose
Choose HASL/Lead-Free HASL if:
- • Budget is the primary concern
- • Using through-hole or large SMD components
- • Don't need fine pitch (<0.5mm) capability
- • Prototyping or low-volume production
Choose ENIG if:
- • Using BGA or fine pitch components
- • Need flat surface for assembly
- • Require wire bonding capability
- • High reliability is critical
Choose OSP if:
- • High volume production with fast turnover
- • Cost-sensitive with fine pitch needs
- • Environmental compliance is important
- • Single reflow process
Choose Immersion Silver if:
- • RF/Microwave applications
- • Need best signal integrity
- • Flat surface with better shelf life than OSP
- • Membrane switch applications