Printed circuit board finishes
All surface finish methods have their pros and cons; the decisive factor is, of course, their application. A short overview of the most common surface finishes is given below. Please contact us if you have any questions about this.
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SURFACE FINISH METALS
All surface finish methods have their pros and cons; the decisive factor is, of course, their application. A short overview of the most common surface finishes is given below. Please contact us if you have any questions about this.(HASL) Tin/Lead hot air solder level
+ Excellent solderability
+ Inexpensive
+ Allows large process windows
+ Tried and tested surface finish
+ Shelf life – min. 12 months
- Not completely flat soldering surfaces
- Non-RoHS-compatible surface finish
(HASL) Lead-free hot air solder level
+ Excellent solderability
+ Tried and tested surface finish
+ Relatively inexpensive
+ Allows large process windows
+ Shelf life – min. 12 months
- Not completely flat soldering surfaces (but more flat than leaded HASL)
Recommended as a replacement for leaded HASL. Should also be regarded as an alternative to other lead-free surface finishes due to its relative flatness.
Immersion Tin
+ Excellent flatness
+ Good solderability
+ Relatively inexpensive
- Sensitive to handling
- Shelf life – up to 6 months
- Coating depth is important, placing high demands on process control
Sometimes recommended as a replacement for ENIG, primarily for BGA assembly.
ENIG (Electroless Nickel & Immersion Gold)
+ Good solderability
+ Tried and tested process
+ Excellent flatness
+ Shelf life 12 months
+ Used as combi process
- Expensive
- Black pad problems – (oxidation of nickel below the gold layer)
- Coating depth is important, placing high demands on process control
OSP (Organic Solder Preservatives)
+ Excellent flatness
+ Inexpensive process
- Poorer shelf life – 3-6 months
- Acceptable solderability
- Unreliable with more than two soldering processes
- Recommended for mass production and when there isn’t too much time between soldering operations
Immersion Silver
+ Excellent flatness
+ Good solderability
+ Inexpensive process
- Requires a special packaging routine
- There should not be a too long interval between soldering operations
- Few suppliers can provide this surface finish