ASTM B-579

Standard Specification for Electrodeposited Coatings of Tin-Lead Alloy
Tin-Lead Alloy Coatings on Steel
Element Weight, %
Tin (Sn) 50 to 70
Lead (Pb) remainder
Service Condition Classification Number Minimum thickness, um
SC4a Fe/SnPb 30 30
SC3a Fe/SnPb 20 20
SC2 Fe/SnPb 10 10
SC1 Fe/SnPb 5 5
SC1 Fe/SnPb 5fb 5
a: an undercoat of 2.5 um copper is recommended
b: flow brightened