A surface finish can be either organic or metallic in nature. Comparing both types and all available options can quickly demonstrate the relative benefits or drawbacks. Typically, the decisive factors when it comes to selecting the most suitable finish is the end application, the assembly process and the design of the PCB itself. Below you can find a brief summary of the most common finishes, however for further or more detailed information, please Viasion and we will be more than happy to answer any of your questions.


HASL – Tin/Lead hot air solder level
Typical thickness 1 – 40um. Shelf life:12 months

Excellent solderabilityInexpensive / Low costAllows large processing windowLong industry experience / well known finishMultiple thermal excursions
Difference in thickness / topography between large and small padsNot suited for < 20mil pitch SMD & BGABridging on fine pitchNot ideal for HDI products

LF HASL – Lead Free hot air solder level
Typical thickness 1 – 40um. Shelf life: 12 months

Immersion finish = excellent flatness
Good for fine pitch / BGA / smaller components
Tried and tested process
Wire bondable
Expensive finish
Black pad concerns on BGA
Can be aggressive to soldermask – larger soldermask dam preferred
Avoid soldermask defined BGA’s
Should not plug holes on one side only

ENIG – Immersion gold / Electroless Nickel Immersion Gold
Typical thickness 3 – 6um Nickel / 0.05 – 0.125um Gold. Shelf life: 12 months

Immersion finish = excellent flatness
Good for fine pitch / BGA / smaller components
Mid range cost for lead free finish
Press fit suitable finish
Good solderability .
Very sensitive to handling – gloves must be used
Tin whisker concerns
Aggressive to soldermask – soldermask dam shall be ≥ 5 mil
Baking prior to use can have a negative effect
Not recommended to use peelable masks
Should not plug holes on one side only

Immersion Sn – Immersion Tin
Typical thickness ≥ 1.0µm. Shelf life: 6 months

Immersion finish = excellent flatness
Good for fine pitch / BGA / smaller components
Mid range cost for lead free finish
Can be reworked .
Very sensitive to handling / tarnishing / cosmetic concerns – gloves must be used
Special packaging required – if packaged opened and not all boards used, it must be resealed quickly.
Short operating window between assembly stages
Not recommended to use peelable masks
Should not plug holes from one side only
Reduced supply chain options to support this finish .

Immersion Ag – Immersion Silver
Typical thickness 0.12 – 0.40um. Shelf life: 6 months

Excellent flatness
Good for fine pitch / BGA / smaller components
Inexpensive / Low cost
Can be reworked
Clean, environmentally friendly process .
Very sensitive to handling – gloves must be used and scratches avoided
Short operating window between assembly stages
Limited thermal cycles so not preferred for multiple soldering processes (>2/3)
Limited shelf life – not ideal for specific freight modes and long stock holding
Very difficult to inspect
Cleaning misprinted solderpaste can have a negative effect on the OSP coating
Baking prior to use can have a negative effect .