Printed circuit board surface finish can be either organic or metallic, and comparing both types and available options can help determine their relative benefits and drawbacks. The most suitable finish is usually chosen based on the end application, assembly process, and circuit board design. Below is a brief summary of the most common finishes, but for further information, please contact us. We will be happy to answer any questions you may have about specific PCB surface finishes.
-
Enig
-
ENEPIG
-
Hasl
-
Lead Free Hasl
-
Immersion Tin
-
Immersion Silver
-
OSP
ENIG – Immersion gold / Electroless Nickel Immersion Gold
Typical thickness 3 – 6um Nickel / 0.05 – 0.125um Gold. Shelf life: 12 months
Pros
- Immersion finish = excellent flatness
- Good for fine pitch / BGA / smaller components
- Tried and tested process
- Wire bondable
Cons
- 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
Electroless Nickel Electroless Palladium Immersion Gold. Typical thickness = Nickel
3 – 6um / Palladium is 0.05 – 0.3um / Gold 0.05 – 0.125um. Shelf life = 12 months
Pros
- Excellent for wire bonding
- Free from black pad concerns
- Immersion finish = excellent flatness
- Palladium reduces impact of nickel on high speed designs
Cons
- Expensive finish
- Not widely available
- Solderability influenced by palladium deposit
HASL – Tin/Lead hot air solder level
Typical thickness 1 – 40um. Shelf life:12 months
Pros
- Excellent solderability
- Inexpensive / Low cost
- Allows large processing window
- Long industry experience / well known finish
- Multiple thermal excursions
Cons
- Difference in thickness / topography between large and small pads
- Not suited for < 20mil pitch SMD & BGA
- Bridging on fine pitch
- Not ideal for HDI products
LF HASL – Lead Free hot air solder level
Typical thickness 1 – 40um. Shelf life: 12 months
Pros
- Excellent solderability
- Relatively inexpensive
- Allows large processing window
- Multiple thermal excursions
Cons
- Difference in thickness / topography between large and small pads – but to a lesser degree than SnPb
- High processing temperature – 260-270 degrees C
- Not suited for < 20mil pitch SMD & BGA
- Bridging on fine pitch
- Not ideal for HDI products
Immersion Sn – Immersion Tin
Typical thickness ≥ 1.0µm. Shelf life: 6 months
Pros
- Immersion finish = excellent flatness
- Good for fine pitch / BGA / smaller components
- Mid range cost for lead free finish
- Press fit suitable finish
- Can be reworked
Cons
- 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 Ag – Immersion Silver
Typical thickness 0.12 – 0.40um. Shelf life: 6 months
Pros
- Immersion finish = excellent flatness
- Good for fine pitch / BGA / smaller components
- Mid range cost for lead free finish
- Can be reworked
Cons
- 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
OSP (Organic Solderability Preservative)
Typical thickness 0.20-0.65µm. Shelf life: 6 months
Pros
- Excellent flatness
- Good for fine pitch / BGA / smaller components
- Inexpensive / Low cost
- Can be reworked
- Clean, environmentally friendly process
Cons
- 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
Contact us
We would love to respond to your queries and help you succeed.
During our business Hours: 9:00～18:00
Contact us
9F, Jinsheng Fortune Plaza, Shajing, Bao'an, Shenzhen, China
