Capabilities & Services Finishes & Specifications
The electroplated finish is often one of the most important components to the success of an electronic device. Products plated at General Metal Finishing have been found in high-reliability, mission-critical assemblies throughout the world. Our experience enables us to help our customers solve challenging plating issues by bringing functional solutions and cost-saving opportunities to their most demanding problems.
Finishes |
Specifications |
NADCAP |
|---|---|---|
| Gold | ASTM B488 | X |
| Mil-G-45204 | X | |
| Mil-DTL-45204 | X | |
| Silver | ASTM B700 | |
| QQ-S-365 | ||
| AMS 2410 | ||
| AMS 2411 | ||
| Palladium | ASTM B679 | |
| Platinum | GE-F70J-WB2 | |
| Copper | ASTM B734 | |
| Mil-C-14550 | ||
| AMS 2418 |
Finishes |
Specifications |
NADCAP |
|---|---|---|
| Nickel (Electroless) | Mil-C-26074 | X |
| AMS-C-26074 | X | |
| AMS 2404 | X | |
| ASTM B733 | X | |
| Nickel (Electrolytic) | AMS-QQ-N-290 | X |
| FED-QQ-N-290 | X | |
| AMS 2403 | X | |
| ASTM B689 | ||
| Sulfamate Nickel | ASTM B689 | |
| AMS-QQ-N-290 | X | |
| Mil-P-27418 | ||
| AMS 2403 | ||
| AMS 2424 | ||
| Boron Nickel | ASTM B607 |
Finishes |
Specifications |
NADCAP |
|---|---|---|
| Tin (Matte/Bright) |
ASTM B545 | |
| Mil-T-10727 | ||
| Tin Lead (90/10, 60/40) |
ASTM B-579 | |
| AMS-P-81728 | ||
| Mil-P-81728 | ||
| Black Ebonol C | Mil-C-13924 | |
| Miralloy™ (Copper, Tin, Zinc Alloy) | ||
| Electropolish (Stainless) | ||
| Passivation | QQ-P-35 | |
| ASTM B912 | ||
| ASTM A967 | ||
| AMS 2700 |
Gold Plating
Gold plating is extensively utilized in manufacturing due to its superior electrical conductivity, excellent corrosion resistance, and ability to enhance the durability of components. It is frequently applied to electronic connectors, printed circuit boards (PCBs), and precision industrial parts to ensure reliable performance in high-demand environments.
Two primary types of gold plating are employed, differentiated by their composition and intended applications:
- Hard Gold: Hard gold plating is alloyed with metals such as nickel or cobalt to increase its hardness and wear resistance. This makes it suitable for applications involving high mechanical stress or repeated contact, such as connectors, switches, and relay contacts.
- Soft Gold: Soft gold plating consists of nearly pure gold, offering exceptional conductivity and solderability. Its properties make it ideal for applications requiring high-performance electrical connections, such as wire bonding, microelectronics, and semiconductor packaging.
The selection of hard or soft gold plating depends on the specific requirements for wear resistance, electrical performance, and the operating environment of the component. Standards include ASTM B488, MIL-G-45204, MIL-DTL-45204, AMS 2422 and AMS 2425.
Silver Plating
Silver plating offers the highest electrical conductivity of all metals. Unfortunately, it does not have the noble characteristics of gold and will form surface tarnish films, especially when exposed to sulfur bearing atmospheres. Silver has good solderability characteristics, even if the silver is somewhat tarnished. It is best suited for engineering purposes that require soldering, higher electrical and thermal conductivity, wear resistance of load bearing surfaces, and superior electrical contact. Silver also functions well as a connector finish in normal force, lower durability signal applications due to its low Contact Resistance values.
Engineered Silver Plating, which PEP General Metal Finishing provides, is deposited 99.9% pure. Standard specification callouts would be through standards QQ-S-365, ASTM B700, AMS 2410, AMS 2411, and AMS 2412.
Tin
Tin has good conductivity and corrosion resistance while enhancing the solderability of substrates not easily soldered to. Pure tin can be obtained in both Bright and Matte finishes. Bright Tin has a high lustre and is generally preferred for electrical contact applications such as bus bars, terminals and switch components not soldered to. When soldering to Bright Tin, dewetting can occur due to organic additives used to brighten the deposit. For solderable applications, Matte Tin is preferred as it’s free of organics found in Bright Tin.
Tin deposits will oxidize over time so storage of the plated components should be considered for extending shelf life. Preplates of other metals, most commonly nickel, are also used as an effective barrier against diffusion and can significantly extend the solderability shelf life of tin plated parts.
Standards for Tin are Mil-T-10727, ASTM B545, and AMS 2408.
Electrolytic Nickel
Nickel is the widest used electroplated coating with a myriad of functional and decorative applications. Bright Nickel is often used in the automotive, electrical, appliance and hardware industries with one of its most important functions being that of an undercoat for Chrome. In heavy deposits it will smooth out a base metal and offer significant corrosion protection.
Nickel is also used for engineering purposes where brightness is not a concern. Pure, unbrightened nickel is often used as a barrier coat for subsequent plated finishes. Sulfamate nickel produces a 99.9% pure nickel deposit that is minimally stressed making it an excellent choice for parts that will be flexed, bent or crimped. It is the recommended choice as an underplate for lead-frames, interconnect pins, and glass-to-metal or ceramic-to-metal seals.
Nickel also has a high melting temperature of 2647F (1452C) so it’s widely used in high temperature applications.
Specified standards are typically AMS-QQ-N-290, ASTM B689, AMS 2403, and Mil-P-27418
Electroless Nickel
Electroless Nickel is generally used as a functional coating rather than decorative. Primary uses for Electroless Nickel would be for Corrosion Resistance, Wear Resistance, Hardness, Lubricity, Uniformity of Deposit, and for the Non-Magnetic properties of high phosphorous alloys.
Unlike electroplating where electrical current is used, Electroless Nickel is plated autocatalytically. Deposition occurs in an aqueous solution containing metal ions along with reducing and complexing agents. Chemical reactions on the surface of the work piece cause the deposition of the nickel alloy. Since there’s no electricity involved and all surfaces are in solution for the same amount of time, the deposit thickness is very uniform. Plating internal surfaces, recessed cavities, etc. becomes a reality with Electroless Nickel. Uniformity and internal coverage are many times not possible with electrolytic nickel deposits.
Specific callouts for Electroless Nickel are most often Mil-C-26074, ASTM B733, and AMS 2404
Tin-Lead Plating
Tin-Lead, many times called Solder Plate, is widely used for functional soldering applications. The ratio of Tin to Lead does affect the melting point of the deposit. Typical ratios of Tin to Lead would be 60/40, 90/10, and 93/7. 60/40 will have the lowest melting point at roughly 374F (190C) while 90/10 will be 421F (217C).
The main purposes for using Tin-lead is its excellent solderability and corrosion protection but also to prevent tin whisker formation that can typically be experienced in 100% pure Tin. The growth of tin whiskers over time can cause failure of electronic components by bridging conductor paths causing a short circuit. However, far reaching impacts have been seen by the Lead Free electronic manufacturing directives mandated by the European Union so alternatives to Tin-Lead deposits remain ongoing.
Mil-P-81728 and ASTM B579 are primary specifications used for Tin-Lead.
Electropolish
Electropolishing is an electrochemical process that enhances the surface of metal parts by removing a thin layer of material, leaving behind a smoother, cleaner finish. This process involves immersing the metal in an electrolyte bath and applying an electric current, which removes microscopic imperfections, burrs, and contaminants. The result is a polished, shiny surface that not only improves the appearance but also increases corrosion resistance, reduces friction, and makes the material easier to clean. Electropolishing is commonly used on stainless steel and other alloys to enhance the durability and longevity of components, especially in industries like food processing, medical devices, and aerospace. The process also minimizes the likelihood of surface cracks, which can lead to material failure, making it a reliable method for improving both function and aesthetics.
