Default for sintered NdFeB
Ni-Cu-Ni
Tri-layer plating with the best balance of corrosion resistance, hardness, and cost. Specify this unless the application demands otherwise.
Coatings & platings
Surface protection,
selected to the use case.
A reference chart of the coatings and platings we run, with notes on environment, durability, and thickness.
How thickness is reported
Coating thickness on the chart represents the base layer (typically nickel and/or copper) plus the topcoat. Total stack thickness can vary with geometry; tight-tolerance parts may require a thinner stack.
Stack vs. single-layer
Most plated finishes (Ni, Au, Ag, Sn) are applied over a Ni-Cu-Ni base. Polymer coatings (epoxy, parylene, PTFE) can be applied direct to magnet or over a primer depending on the requirement.
Coatings reference
Available finishes.
| Finish | Appearance | Typical thickness | Salt spray (hrs) | Max temp | Notes |
|---|---|---|---|---|---|
| Ni-Cu-Ni | Bright silver | 15–25 μm | 48–72 | 200 °C | Industry default for sintered NdFeB. Hard, conductive, paint-friendly. |
| Nickel (Ni) | Matte to bright silver | 10–20 μm | 24–48 | 200 °C | Single-layer nickel. Lower corrosion resistance than full Ni-Cu-Ni stack. |
| Zinc (Zn) | Silver-gray | 8–15 μm | 12–48 | 120 °C | Sacrificial finish. Cost-effective for low-humidity indoor use. |
| Epoxy (black) | Glossy black | 15–25 μm | 96–500+ | 150 °C | Excellent corrosion resistance. Common over Ni-Cu-Ni for harsh environments. |
| Epoxy (gray) | Matte gray | 15–25 μm | 96–500+ | 150 °C | Same protection as black epoxy with a neutral finish for visible parts. |
| Parylene C | Clear / translucent | 5–25 μm | 200+ | 125 °C | Pinhole-free conformal coating. Standard for medical implantables and bio-compatible applications. |
| Gold (Au) | Bright gold | 0.5–2 μm | 96+ | 200 °C | Over Ni base. Excellent conductivity, biocompatibility, and tarnish resistance. |
| Silver (Ag) | Bright silver | 2–10 μm | 72+ | 200 °C | High electrical/thermal conductivity. Tarnishes; passivation recommended. |
| Tin (Sn) | Bright silver | 5–15 μm | 48–96 | 150 °C | Solderable. Used for magnets that interface with PCBs or assemblies via solder. |
| PTFE / Teflon | Off-white / matte | 10–30 μm | 96+ | 260 °C | Low-friction, chemically inert. Used in fluid-handling and contamination-sensitive environments. |
| Phosphate | Dark gray to black | 2–5 μm | 8–24 | 200 °C | Chemical conversion. Best as primer under paint or epoxy, not as standalone protection. |
| Black Nickel | Charcoal black | 10–20 μm | 24–72 | 200 °C | Decorative dark finish over Ni-Cu-Ni. Used where visible aesthetics matter. |
| Chrome | Bright reflective | 5–15 μm | 96+ | 200 °C | Hard, reflective, tarnish-resistant. Less common on magnets but available on request. |
Salt-spray hours and thicknesses listed are typical ranges. Actual performance depends on substrate prep, geometry, edge condition, and the specific bath chemistry used. Custom stacks and thicknesses are available; share your environment and we'll spec the right finish.
Selection guide
Picking a finish.
High humidity / outdoor / marine
Epoxy over Ni-Cu-Ni
Add a 15–25 μm epoxy topcoat for salt-spray performance into the hundreds of hours. Black or gray.
Medical implantable
Parylene C
Pinhole-free, biocompatible, conformal. Standard for any magnet entering the body or a sterilization cycle.
Solderable to PCB
Tin (Sn)
Used when the magnet itself becomes part of a soldered assembly. Plated over a Ni base.
Conductivity / thermal
Gold or Silver
For RF, sensor contact surfaces, or heat-spreading applications. Both go over a nickel base.
Fluid handling
PTFE / Teflon
Low friction, chemically inert, suitable for pump impellers and contamination-sensitive flow paths.
Need a custom stack?
If your environment falls outside the standard finishes, we'll work with you on a custom multi-layer specification.
Talk to an engineer