PCB Board
Name: Rube Goldberg
Tel: +86-13697458841
E-mail: sales@aldpcb.com
Add: No.67 Chun Hui Si Street Luogang District,Guangzhou City,Guangdong Province,China
Six Surface Finishes of PCB
The PCB surface finish can be either organic or metallic in nature. At present, the environmental problems involved in the PCB production process are particularly prominent. As the environmental protection calls are getting higher and higher, the surface treatment process of PCBs will definitely change in the future. Comparing several types and all available options can quickly demonstrate the relative benefits or drawbacks. Below is a brief summary of the most common finishes.
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HASL - Tin/Lead hot air solder level |
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Lifetime（month） |
12 |
Process complexity |
High |
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Cost |
Medium |
Process temperature(℃) |
250 |
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Thickness（um） |
1-40 |
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Advantages |
1.Excellent solderability 2.Inexpensive / Low cost 3.Allows large processing window 4.Long industry experience / well known finish 5.Multiple thermal excursions |
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Disadvantages |
1.Difference in thickness / topography between large and small pads 2.Not suited for < 20mil pitch SMD & BGA 3.Bridging on fine pitch 4.Not ideal for HDI products |
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LF HASL - Lead Free hot air solder level |
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Lifetime（month） |
12 |
Process complexity |
High |
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Cost |
High |
Process temperature(℃) |
260-270 |
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Thickness（um） |
1-40 |
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Advantages |
1.Excellent solderability 2.Relatively inexpensive 3.Allows large processing window 4.Multiple thermal excursions |
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Disadvantages |
1.Difference in thickness / topography between large and small pads - but to a lesser degree than SnPb 2.High processing temperature - 260-270 degrees C 3.Not suited for < 20mil pitch SMD & BGA 4.Bridging on fine pitch 5.Not ideal for HDI products |
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ENIG - Immersion gold / Electroless Nickel Immersion Gold |
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Lifetime（month） |
12 |
Process complexity |
High |
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Cost |
High |
Process temperature(℃) |
80 |
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Thickness（um） |
3 - 6 Nickel, 0.05 - 0.125 Gold |
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Advantages |
1.Immersion finish = excellent flatness 2.Good for fine pitch / BGA / smaller components 3.Tried and tested process 4.Wire bondable |
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Disadvantages |
1.Expensive finish 2.Black pad concerns on BGA 3.Can be aggressive to soldermask - larger soldermask dam preferred 4.Avoid soldermask defined BGA's 5.Should not plug holes on one side only |
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Immersion Sn - Immersion Tin |
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Lifetime（month） |
6 |
Process complexity |
Medium |
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Cost |
Medium |
Process temperature(℃) |
50 |
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Thickness（um） |
≥ 1.0 |
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Advantages |
1.Immersion finish = excellent flatness 2.Good for fine pitch / BGA / smaller components 3.Mid range cost for lead free finish 4.Press fit suitable finish 5.Good solderability |
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Disadvantages |
1.Very sensitive to handling - gloves must be used 2.Tin whisker concerns 3.Aggressive to soldermask - soldermask dam shall be ≥ 5 mil 4.Baking prior to use can have a negative effect 5.Not recommended to use peelable masks 6.Should not plug holes on one side only |
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Immersion Ag - Immersion Silver |
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Lifetime（month） |
6 |
Process complexity |
Medium |
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Cost |
Medium |
Process temperature(℃) |
70 |
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Thickness（um） |
0.12 - 0.40 |
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Advantages |
1.Immersion finish = excellent flatness 2.Good for fine pitch / BGA / smaller components 3.Mid range cost for lead free finish 4.Can be reworked |
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Disadvantages |
1.Very sensitive to handling / tarnishing / cosmetic concerns - gloves must be used 2.Special packaging required - if packaged opened and not all boards used, it must be resealed quickly 3.Short operating window between assembly stages 4.Not recommended to use peelable masks 5.Should not plug holes from one side only 6.Reduced supply chain options to support this finish |
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OSP - Organic Solderability Preservative |
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Lifetime（month） |
6 |
Process complexity |
Low |
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Cost |
Low |
Process temperature(℃) |
40 |
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Thickness（um） |
0.20-0.65 |
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Advantages |
1.Excellent flatness 2.Good for fine pitch / BGA / smaller components 3.Inexpensive / Low cost 4.Can be reworked 5.Clean, environmentally friendly process |
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Disadvantages |
1.Very sensitive to handling - gloves must be used and scratches avoided 2.Short operating window between assembly stages 3.Limited thermal cycles so not preferred for multiple soldering processes (>2/3) 4.Limited shelf life - not ideal for specific freight modes and long stock holding 5.Very difficult to inspect 6.Cleaning misprinted solderpaste can have a negative effect on the OSP coating 7.Baking prior to use can have a negative effect |
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Finding further or more detailed information, please contact: jessica@aldpcb.com, eng@aldpcb.com, and we will be more than happy to answer any of your questions.
