Metal Surface Finishing and MIL Spec Plating

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PA&E has decades of experience in ceramic-to-metal finishing. We are experts in plating a variety of metals including: aluminum, titanium, iron/nickel alloys, copper and even our explosively bimetallic transition materials. We have a staff of certified chemical and process engineers which allows us to plate your parts in house where we can maintain finite control over these critical finishing process.

Chromate Conversion: MIL–DTL–5541

In the chromate conversion process, the metal surface of a part is converted to a superficial layer containing a complex mixture of chromium compounds. The chromate film is soft when freshly formed, but once dried and aged, the film becomes more abrasive resistant. Chromate conversion coatings provide excellent corrosion resistance.

Electroless Nickel: AMS-C-26074 Class 3 & 4; AMS-2404 Class 3 & 4; ASTM-B488: Type I, Code A & C, Type II Grade C, Type III Grade A

Electroless nickel describes the plating of nickel deposits, which may contain phosphorus and boron, onto catalytic metallic or catalyzed non-metallic substrates by chemical reduction. Unlike electrolytic plated nickel coatings, electroless nickel coatings produce very uniform, hard, and lubricious coatings, without an externally applied electric current, and are normally identified according to their phosphorus content.

Plating Specification* Notes Thickness**
AMS-2404, Class 3 Electroless Nickel Electroless nickel is Enova 583. Mid-phos content of 4-8% +/-50 microinches, minimum of 25 microinches, maximum 1000 microinches
AMS-2404, Class 4 Electroless Nickel
AMS-C-26074, Class 3, Grade A & B Electroless Nickel
AMS-C-26074, Class 4 & 5, Grade A & B Electroless Nickel
ASTM-B-733, Class 1, Type 1 & 4 only
ASTM-B-733, Class 4 & 5 Type I & IV only

Electrolytic Gold – ASTM-B-488 and MIL-DTL-45204

Electrolytic gold offers high electrical conductivity, solder-ability, weld-ability, infrared-reflectivity, and excellent corrosion resistance (as well as sealing the nickel surface to eliminate passivation). Electrolytic gold is primarily used in the electrical industry for RF connectors and printed circuits, and in the electronics industry for transistor integrated circuits.

Plating Specification Thickness**
ASTM-B-488, Type I, Code A & C +/-25 microinches, minimum of 25 microinches, maximum 250 microinches
ASTM-B-488, Type II & III, Code  C
MIL-DTL-45204, Type I, Grade A & C
MIL-DTL-45204, Type II, Grade C
MIL-DTL-45204, Type III, Grade A

Electrolytic Nickel – QQ-N-290

Unlike electroless nickel, electrolytic nickel uses an external current supply to plate the nickel to various substrates. It is one of the most widely used types of plating due to fact it can be welded unlike electroless nickel. Electrolytic nickel comes in different forms, and is one of the most popular being sulfamate nickel, which has a dull, matte finish, and is often used as an undercoating for gold applications.

Plating Specification* Notes Thickness**
AMS-QQ-N-290, Class 1 Use of other grades possible depending on geometry and base metal +/-50 microinches, minimum of 25 microinches, maximum 400 microinches
AMS-QQ-N-290, Class 2,

*Grade call-outs on the nickel specifications are for thickness. PA&E generally calls out its own thickness ranges.

**Thickness ranges are best case, these can be effected by geometry and base metal.