Standard Specification for Electrodeposited Coatings of Gold

This specification establishes the requirements for electrodeposited gold coatings.

Coatings are classified into types based on minimum purity characteristics and codes which provide Knoop hardness.


 ASTM Type  Purity, Code, and Finish
 Type I  99.7% pure Au with a hardness from A (90 HK25 max) to C (130-200 HK25)
 Type II  99.0% pure Au (hard Au) with hardness from B (91-129 KH25) to D (>200 HK25)
 Type III        99.9% pure Au is soft gold with a hardness of A only (90 HK25 Max)


 ASTM Code  Knoop Hardness
 Code A                  90 HK25 max
 Code B   91-129 KH25
 Code C         130-200 HK25
 Code D   over 200 HK25

Purity (Type) and Hardness (Grade) Relationship

 ASTM Type  Code
 Type I                 Code A, B, and C
 Type II  Code B, C, and D
 Type III        Code A Only


 Class  Minimum Thickness [um]
 0.25                                      0.25
 0.50   0.50
 0.75         0.75
 1.0   1.0
 1.25   1.25
 2.5   2.5
 5.0   5.0

Recommended Drawing Call-Outs:

  • Plate electrodeposited Nickel / Gold per ASTM-B-488
  • Thickness requirements per IPC-6012 or IPC-6013 (respectively), or follow table below: 


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