The Definitive Guide to an Electronic Assembly Design Review / 10
This table provides helpful information when you consider surface finish attributes and their
performance based on the intended use. The table reveals positives and negatives associated with
each finish. Additionally, the application environment and operating conditions must also be
considered to ensure the best surface selection.
5
PCB Analysis (cont.)
Surface Finish Cost
Corrosion
Resistance
ICT Hole Fill Fine Pitch Cosmetics Comments
Imm Silver
Low
Low
Low
Mod
High
Poor
Mod
Good
Good
Mod
Good
Poor
Good
Good
Good
Mod
Poor
Good
Mod
Good
Good
Good
Mod
Good
Good
Poor
Mod
Good
Mod
Good
Good surface finish for soldering
and testing, tarnish & creep
corrosion are the weaknesses
Required pasting of test pads/vias.
Difficult to achieve LF hole fill,
especially on >0.062 boards.
Phenolic laminate recommended.
New equipment required. Flatness
is better than SnPb.
Solderability/hole-fill may be a
problem on double sided PCBs.
Shelf life.
Galvanic driven creep corrosion
canoccur
if Cu is exposed. Ni-Sn
interface is brittle with LF. Black
pad issues remain.
HST OSP
LF HASL
Imm Tin
ENIG
