Electrolytic Nickel, Gold

(Hard & Soft Gold)

Electrolytic Nickel, Gold (Hard & Soft Gold), or Nickel / Gold

IPC Codes: G, GS, GWB-1, GWB-2, N, NB (Depending on application).

Depending on applications, printed circuit board technologies use gold extensively. Gold has good electrical conductivity, tarnish resistance, solderability after storage, and being excellent etch resist.  Electrolytic Ni/Au has a layer of gold plating over a base of electroplated nickel.  Hard or Soft Gold can be used with each option.

 

Diagram illustrating the different applications of Electroplating.

Diagram illustrating the different applications of Electroplating. 

Hard gold is a gold alloy with complexes of cobalt and/or nickel. is typically used for minimum contact resistance, connector tabs.  Hard gold is not suitable for wire bonding.

  • Complies with
    • MIL-DTL-45204 Type I and II, Grade C
    • ASTM B 488, Types I and II, Code C
  • Hardness range of 130-200 Knoop.
  • The Gold purity is a minimum of 99.70%.

Soft gold finish is typically used for boards designed mostly for applications that require wire bonding, high solderability and weldability.

  • Complies with
    • MIL-DTL-45204, Type III, Grade A
    • ASTM B 488, Types III, Code A
  • Hardness maximum of 90 Knoop.
  • The Gold purity is a minimum of 99.90%.

Nickel is a low stress, semi-bright, ductile deposit.

  • Complies with
    • SAE AMS-QQ-N-290 Class 1 and 2
    • SAE AMS2423
    • SAE AMS2403
    • ASTM B689-97
    • SAE AMS2424 (Special Request Required)

IPC-6011 gives a guideline for the thickness requirements for each layer being per the table below but for some applications different thickness are specified by our customer.

 

IPC Thickness Requirements per IPC-6011
CodeFinishThickness
GGold for edge printed board connectors and areas not to be solderedClass 1 & 2
31.5 µin minimum
Class 3
49.21 µin minimum
GSGold Electroplate on areas to be soldered17.72 µin maximum
GWB-1Gold Electroplate for areas to be wire bonded (ultrasonic)1.97 µin minimum
Electrolytic nickel under gold for areas to be wire bonded (ultrasonic)118 µin minimum
GWB-2Gold Electroplate for areas to be wire bonded (thermosonic)Class 1 & 2
11.8 µin minimum
Class 3
31.5 µin minimum
Electrolytic nickel under gold for areas to be wire bonded (thermosonic)118 µin minimum
NNickel – Electroplate for edge printed board connectorsClass 1
78.7 µin minimum
Class 2 & 3
98.4 µin minimum
NBNickel – Electroplate as a barrier51.2 µin minimum

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