MIL-G-45204 Gold Plating Specifications
What is MIL-G-45204?
MIL-G-45204 is a gold plating specification for the electrodeposition of gold and the properties of the deposit. These specifications are typically used within the aerospace, automotive, home electronics, oil & gas, as well as the pharmaceutical industry. Common applications that use this type of specification are barrels, connector pins, electrical switch contacts, and other high-tech electronic components.
When MIL-G-45204 is on a print, the wrong supplier can stall a program. A shop that quotes without the right Type and Grade controls, the correct underplate, or the certification documentation to back the callout will ship parts that fail incoming inspection. Accurate Precision Plating gold plates all mediums to meet MIL-G-45204 plating specification standards, in all types (Type I, II, and III) and Grade A-D. We also certify to its current active replacement, MIL-DTL-45204, so engineers and procurement managers working from legacy or current drawings can issue a PO with confidence.
MIL-G-45204 Has Been Superseded by MIL-DTL-45204
MIL-G-45204 was officially superseded by MIL-DTL-45204, the current active detail specification maintained by the U.S. Army Research Laboratory for an electrodeposited gold coating. Both designations remain in active use across defense, aerospace, and electronics supply chains. Newer drawings reference MIL-DTL-45204, while a large volume of legacy prints still carry the original MIL-G-45204 callout. We plate to the active spec in either case and supply certification language that matches the callout on your drawing. For full Type, Grade, and Class details under the active spec, see our MIL-DTL-45204 gold plating page.
Types and Grades Under MIL-G-45204
The different specifications are related to the different purity levels of hard and soft gold. Below is a description of each of these types:
| MIL-G-45204 | ||
|---|---|---|
| Type | Purity | Hardness |
| Type I | 99.7% Gold Minimum | A (90 HK25 max) to C (130-200 HK25) |
| Type II | 99.0% Gold Minimum | B (91-129 KH25) to D (> 200 HK25) |
| Type III | 99.9% Gold Minimum | A only (90 HK25 Max) |
Type I can be used for the improvement of solderability, electrical contacts requiring high reliability.
Type II is typically used form general purpose applications for hardening agents in the gold plating can oxidize under conditions of high temperature.
Type III is most commonly used for thermocompression, bonding, nuclear engineering, as well as high-temperature applications and semiconductor components.
Specifying the right Type and Grade combination is critical. Soft gold (Type III, Grade A) is required for wire bonding and solderable PCB pads. Hard gold (Type II, Grade C or D) is required for connector contacts subjected to repeated mating cycles. Our team confirms the combination against your application before plating begins.
Substrates and Underplates
Most gold deposits to MIL-G-45204 and MIL-DTL-45204 require a nickel underplate to prevent base-metal diffusion and improve wear performance. Silver and copper-plus-silver are not permitted as underplates. We plate gold over a broad range of base metals, including copper, brass, beryllium copper, Kovar, stainless steel, and aluminum, all delivered under our mil-spec plating services program with full certifications and standards documentation.
Request a Quote for MIL-G-45204 Gold Plating
If you have any questions about our gold plating standards or need any more information on our capabilities, please feel free to contact us today or call at (281) 598-8835. Specify your Type, Grade, thickness requirement, substrate, and quantity, and our team will confirm compliance capability and return a quote. Request a quote for MIL-DTL-45204 gold plating to qualify Accurate Precision Plating as your certified gold plating source.
FAQs
How does MIL-DTL-45204 compare to ASTM B488 and AMS 2422?
MIL-DTL-45204, ASTM B488, and AMS 2422 are the three primary specifications for electrodeposited gold coatings, and the Type and Grade classifications across them are closely aligned. MIL-DTL-45204 is the active military detail specification and is the most common callout on defense and aerospace prints. ASTM B488 is the equivalent commercial engineering standard used across electronics, telecommunications, and connector manufacturing. AMS 2422 is the SAE aerospace standard most often referenced on aviation and propulsion drawings. Accurate Precision Plating is qualified to plate gold to all three specifications, including MIL-G-45204, in Type I, II, and III at Grades A and C. If your print references one spec but your supply chain works in another, our team can confirm the cross-reference before plating begins.
What thickness class should I specify under MIL-DTL-45204 or MIL-G-45204?
MIL-DTL-45204 defines eight thickness classes, from Class 00 (0.00002 inch minimum) through Class 6 (0.00150 inch minimum). The right class depends on the application. Class 00 and Class 0 are typical for solderability and wire bonding, where a very thin pure gold layer is sufficient. Class 1 and Class 2 are standard for general electrical contacts and connector pins. Class 3 through Class 6 are specified for high-cycle separable contacts, wear-resistant edge fingers, and applications requiring extended service life in harsh environments. If your drawing does not call out a class, our team will recommend a thickness based on your application, mating cycles, and operating environment before quoting.
What certifications and test documentation are provided with MIL-G-45204 gold plating?
Every MIL-G-45204 and MIL-DTL-45204 gold plating order from Accurate Precision Plating ships with full certification documentation, including a Certificate of Conformance that references the spec, Type, Grade, Class, and substrate plated. Our processes are certified to ISO 9001:2015, and we perform non-destructive thickness testing in accordance with ASTM B568 using Fischerscope X-Ray equipment with a margin of error under 1 percent. Additional testing for adhesion, hardness, purity, and solderability is available on request, including 100 percent part testing for high-reliability programs. Test reports and any required first-article inspection documentation are included with the shipment.
Contact Accurate Precision Plating
click to request a quote or call us at 866.598.8063