Gold Plating Services
Mid-Atlantic Finishing’s gold plating services conform to most specifications.
Gold is a highly conductive precious metal that provides good corrosion, tarnish, and low contact resistance. The final product will be yellow to orange in color depending on proprietary process used. A semi-bright finish maybe applied depending on basis metal. Our gold plating services also provides excellent solder-ability.
Unless otherwise specified, an intermediate nickel plate is required on copper base alloys or copper plated surfaces prior to the gold plating.
Gold Plating Services To The Following Standards:
Note: ASTM B488 underwent a major revision from 1995 to 2001. The Type callout of the ASTM was revised to parallel that of MIL-G-45204 such that the Type and Codes of the ASTM and MIL specs are synonymous.
|Type I:||99.7% pure gold with a hardness ranging from A (90 HK25 max) to C (130-200 HK25).|
|Type II:||99.0% pure gold often referred to as hard gold with a hardness ranging from B (91-129 KH25) to D (> 200 HK25).|
|Type III:||99.9% pure gold often referred to as soft gold with a hardness of A only (90 HK25 Max).|
|Code A:||90 HK25 Maximum|
|Code B:||91-129 HK25|
|Code C:||130-200 HK25|
|Code D:||> 200 HK25|
|Relationship Between Purity and Hardness (ASTM B488-01 and Newer)|
|I||A, B and C|
|II||B, C and D|
|Class||Minimum Thickness [um]|
|Nickel Underplating – For thickness classes except 5.0, a nickel underplating shall be applied before the gold coating when the product is made from copper or copper alloy. Nickel Underplating is also applied for other reasons indicated below.
|Reasons for Using a Nickel Underplate|
|1. Diffusion Barrier (E.g. migration of zinc into the gold layer from a brass substrate)
2 Leveling Layer (Brightening)
3 Pore Corrosion Inhibitor
4 Tarnish Creepage Inhibitor for Gold
5 Load-Bearing Underlayer for Contacting Surfaces
|Type I:||99.7 percent gold minimum|
|Type II:||99.0 percent gold minimum|
|Type III:||99.9 percent gold minimum|
|Grade A:||Knoop hardness 90 max|
|Grade B:||Knoop hardness 91-129, incl.|
|Grade C:||Knoop hardness 130-200, incl.|
|Grade D:||Knoop hardness 201 and over.|
|If the hardness grade for the gold coating is not specified, Type I shall be furnished at hardness Grade A (90 Knoop max) and Type II shall be furnished at hardness Grade C (130 to 200 Knoop)|
|Type I||A, B or C|
|Type II||B, C or D|
|Type III||A only|
|Class 00 – |
Class 0 –
Class 1 –
Class 2 –
Class 3 –
Class 4 –
Class 5 –
Class 6 –
|0.00002 inch thick, minimum
0.00003 inch thick, minimum
0.00005 inch thick, minimum
0.00010 inch thick, minimum
0.00020 inch thick, minimum
0.00030 inch thick, minimum
0.00050 inch thick, minimum
0.00150 inch thick, minimum
|Underplate Requirements per section 6.3: a copper, nickel, or copper plus nickel underplate may be used, depending on the application and the environment. Silver or copper plus silver may not be used unless required by item specification. A soft gold strike from a separate plating tank should follow any other undercoating and precede the final gold coating to improve adhesion and prevent contamination of the main gold plating solution by metallic impurities. When applied to a copper rich surface such as brass, bronze or beryllium copper or a copper plate or strike, an antidiffussion underplate such as nickel shall be applied.|
Copper Flash or Copper Strike: A copper flash or copper strike shall be electro-deposited from a suitable plating solution, except as exempted below.
When parts to be plated are made of copper or copper alloy containing less than 15% zinc, the copper flash or copper strike may be omitted.
Nickel Flash or Nickel Strike: A nickel flash or nickel strike shall be electro-deposited from a suitable nickel plating solution over the copper, copper alloy containing less than 15% zinc, copper flash or copper strike as applicable.
Copper Flash or Strike: Not less than 0.0001 inch (2.5um)
Nickel Strike: Not less than 0.0001 inch (2.5um)
Gold Plate: Note less than 0.00005 inch (1.27um) on all surfaces on which gold plating is specified.
Purity: Gold, as plated, shall be not less than 99.0% pure, determined by a method acceptable to purchaser.