Published on 10/13/2026
Open a bag of RF connectors and the center pins are gold even on a two-dollar part. That looks like jewelry on a part meant for cheap cable. It is not. Gold plating solves a specific set of problems at the contact, and the metal underneath it solves another.
Short answer: RF connectors are gold plated because gold does not oxidize, keeps contact resistance low and stable over thousands of cycles, and survives storage. Gold is not the best conductor. Silver is. Gold wins on reliability, which is what a mated connector needs.
Here is what the plating does, how thick it should be, and when other finishes are the better choice.
On This Page
| Property | Gold | Silver | Bare copper or brass |
|---|---|---|---|
| Conductivity (relative) | 0.7 | 1.05 | 1.0 |
| Oxidizes in air | No | Tarnishes (sulfide) | Yes, quickly |
| Contact resistance over time | Stable | Rises as it tarnishes | Rises, then fails |
| Wear resistance | Soft but good with hard gold | Soft | Moderate |
| Cost | High | Moderate | Low |
Key idea: A connector contact needs low, stable resistance at very small contact area and low force. Oxide films break that. Gold has no oxide film, so the contact stays metal to metal.
Gold is almost never plated directly on brass or beryllium copper. A nickel underplate (typically 50 to 100 microinches, or 1.3 to 2.5 micrometers) goes first. It blocks copper and zinc from diffusing into the gold, which would form oxides at the surface, and it gives a hard base for the thin gold layer.
Typical gold thickness is 30 to 50 microinches (0.76 to 1.3 micrometers) for standard connectors, and thicker for high-cycle precision parts. At 1 GHz the skin depth in gold is about 2.5 micrometers. At 10 GHz it is about 0.8 micrometers. So at X-band and above, the current runs mostly in the gold, and at lower frequency it spreads into the layers below.
Specify the right finish
Tell us the frequency, cycle count and environment. We build assemblies with connectors plated for the job and sweep each one on a VNA before shipment.
Talk to an Engineer| Finish | Where it is used | Tradeoff |
|---|---|---|
| Gold over nickel | General RF, instruments, aerospace | Best all-round contact |
| Silver | High-power, low-loss, PIM-sensitive | Tarnishes; protect or use sealed |
| Tri-metal (copper-tin-zinc) | Low PIM base station parts | Non-magnetic, low PIM, cheaper |
| Passivated stainless steel | Bodies of SMA, 2.92 mm | Strong, corrosion resistant |
| Nickel (bright) | Bodies, low cost | Magnetic; can raise PIM |
Magnetic nickel under thin gold is one reason low-PIM connectors avoid nickel entirely. See our PIM guide on this blog.
Choose gold when
Be careful of
Why do RF connectors have gold-plated pins?
Gold does not oxidize, so contact resistance stays low and stable. It also survives storage and repeated mating.
Is gold a better conductor than copper?
No. Silver and copper conduct better. Gold is used for its stability, not its conductivity.
How thick is gold plating on an SMA connector?
Typically 30 to 50 microinches (0.76 to 1.3 micrometers) over nickel, depending on the grade.
Does gold plating affect RF performance?
Very little. At 10 GHz and above the current flows mostly in the gold, but the layer is thin enough that loss stays small.
Are silver connectors better than gold?
For conductivity yes, but silver tarnishes. It is used in sealed or high-power parts.
Why is there nickel under the gold?
It blocks diffusion from the base metal and gives a hard, even base. Low-PIM parts replace it with a non-magnetic barrier.
Gold plating is about reliability at the contact, not about conductivity. Match the plating to the cycle count, the environment and the sensitivity of your system.
SigmaRF builds assemblies with gold-plated contacts from facilities in India (Vadodara) and the USA (Cleveland area), VNA-swept before shipment, with lead times as short as 2 days.
Need a specific plating spec?
Send the requirement and we will quote it.
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