MIL-DTL-45204D Detailed Specification: Gold Plated, Electro Deposited

The “MIL-DTL-45204D Detailed Specifications: Gold Plating, Electrodeposition” standard, developed by the United States Department of Defense , describes the requirements for electroplating gold on metallic surfaces.

According to this standard, gold plating is provided in the following types, grades and hardness levels:

• The following types include the following minimum gold levels (purity) specified in the table titled “Types” provided in the standard:
  • Type I: 99,7 percent
  • Type II: 99,0 percent
  • Type III: 99,9 percent
• The grades listed in the table titled “Grades” provided in the Standard are assigned to the above types. If the hardness grade for gold plating is not specified in the contract or purchase order, Type I is provided with a hardness grade of A and Type II is provided with a hardness grade of C.
  • Class A: maximum 90 hardness (Knoop)
  • Class B: Hardness between 91-129 (Knoop)
  • Class C: Hardness between 130-200 (Knoop)
  • Class D: 201 and above hardness (Knoop)
• The purity and hardness combinations should be as specified in the table titled “Hardness versus Purity” given in the standard.
  • Type I: A, B or C
  • Type II: B, C or D
  • Type III A (only)

Unless otherwise specified in the contract or purchase order, the thickness must conform to the class definition specified in the table provided in the standard.

The requirements in this standard are specified as follows:

• Coating materials and processes: The materials and processes used will produce coatings that meet the requirements of this specification. Glossy or matt deposits are acceptable unless otherwise specified in the contract or purchase order.
• Base metal: The base metal must be free from defects, scratches, pits, non-conductive inclusions, and mill and die marks that would adversely affect the appearance and performance of coatings applied thereto, even if best coating practice is followed.
  • Pre-coating operations: Unless otherwise specified in the contract or purchase order, the coating shall be applied after all base metal heat treatments and mechanical operations such as machining, soldering, welding, forming and impregnation have been completed. This requirement does not prohibit certain operations that must be performed after coating, such as embrittlement removal, heat treatment and forming operations such as crimping electrical connections.
  • Coating of steel parts: Unless otherwise specified in the contract or purchase order, steel parts with an ultimate tensile strength of 220.000 psi or greater should not be coated without specific approval from the procurement activity.
  • Stress relief treatment: All steel parts shall be stress relieved at 3°C plus/minus 191°C for 14 hours or more prior to cleaning and coating if they contain tensile stresses resulting from machining, grinding or cold forming operations. Cold straightened parts are considered to contain damaging stresses. The temperature and time at temperature shall be such that maximum stress relief is obtained without reducing the hardness below the specified minimum.
• Pre-treatment: Products should be cleaned, pickled or otherwise pre-treated as required. Acid pickling is prohibited on high strength steels.
• Strikes: When gold plating is preceded by a strike or a strike and bottom plate, it shall be as specified in the contract or purchase order. For outdoor use and when the base metal is low alloy steel or other non-copper base metal such as zinc, the thickness of the strike and bottom plate shall be subtracted by at least 0,03 mm from the thickness of the specified gold plating. Unless otherwise specified in the contract or purchase order, gold-on-silver bottom plate combinations shall be excluded from electronic equipment. Silver or copper plus silver shall not be used as a bottom plate unless product specifications require it. In addition, when gold is applied to a copper-rich surface such as brass, bronze or beryllium copper or copper plate or strike, a diffusion inhibitor bottom plate such as nickel shall be applied.
• Coating equipment and processes: Unless otherwise specified in the contract or purchase order, the coating equipment and processes used should be at the option of the supplier.
• Coating Specification - Thickness: The minimum thickness of gold deposited on critical surfaces for each grade of gold plating shall conform to this standard. Critical surfaces shall include all surfaces capable of contact with a 19 mm diameter sphere and any additional functional surfaces specified on the applicable drawings, contract or purchase order. However, the coating on non-critical, non-functional surfaces shall be of sufficient thickness to ensure continuity and uniform appearance of the coating.
• Coating properties - Adhesion. The adhesion of the gold coating and any sub-coating shall be such that the coating and sub-coating will not separate from each other or from the base metal when tested in accordance with this standard.
• Coating properties - Hardness: The Knoop hardness of the coating shall be in accordance with the class specified in the contract or purchase order and shall be determined in accordance with this standard.
• Coating properties - Heat resistance: When heat resistance is specified, gold-plated parts shall not show blistering, discoloration or visible white or crystalline film when tested in accordance with this standard.
• Coating Specification - Smoothness: If a degree of surface smoothness of the finished product is required, the degree shall be specified in the contract or purchase order. Methods for measuring surface smoothness shall be approved by the procurement activity.
• Coating Properties - Solderability: When solderability is required by the procurement activity or specified in the contract or purchase order, the gold plating shall meet the following solderability requirements. When the gold plating is subjected to solderability testing, the solder coating shall be uniform, free of lumps, and shall not flake or peel when subjected to an adhesion test.
• Plating specifications - Composition: The type (purity) of gold must be as stated in the contract or purchase order.
  • Impurities - Type I, Grade A, and Type III: Metallic contaminants such as chromium, copper, tin, lead, silver, cadmium, or zinc shall not be present in the sediment in a concentration greater than 0,1 percent. The combined weight percent of iron, nickel, and cobalt shall be less than 0,050, and none of these three elements shall be present in amounts greater than 0,030 weight percent.
  • Impurities - Type I, Grades B and C, and Type II: Individual metallic impurities in the bed shall not exceed 0,1 percent. Metallic hardening agents intentionally added to the bath shall not be considered impurities.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "MIL-DTL-45204D Detailed features: Gold plating, electro deposit" standard are also provided to businesses.