ASTM B-545

Standard Specification for Electrodeposited Coatings of Tin
Class Minimum Thickness Application
A 2.5 um (100 u”) Mild service conditions.
B 5.0 um (200 u”) Mild service conditions. Facilitates soldering.
C

8.0 um (320 u”)

10 um for Steel substrates

Moderate , usually indoor, exposure conditions. Retention of solderability.
D

15 um ( 600 u”)

20 um for Steel substrates

Severe service. Exposure to dampness and mild corrosion from moderate environments.
E 30 um ( 1200 u”) Very severe service conditions including elevated temperatures where metal diffusion process is accelerated.
F 1.5 um ( 60 u”) Similar to Class A. Short term contact applications