Home / Copper RF, Waveguide and Cavity Parts
Copper RF, Waveguide and Cavity Parts
At high frequency current runs in a thin layer at the surface, so surface roughness is loss. RF copper parts are specified by finish and dimensional accuracy in a way most machined parts are not, and the shop has to understand which faces carry the field.
We match RF work to shops that already hold fine finishes in copper and know why a smeared surface is an electrical defect rather than a cosmetic one.
What the part needs
- Grade
- C10100 or C11000. Free-machining grades are acceptable for some fittings, but check the requirement first.
- Finish on field surfaces
- Ra 0.4 to 0.8 micrometre is typical. State it per face, and name which faces carry the field.
- Dimensional accuracy
- Internal cavity dimensions set the frequency response. Tolerance them, and leave the outside loose.
- Plating
- Silver over nickel is common on field surfaces. Specify thickness on the field face separately from the rest.
- Joining
- Flanges and multi piece cavities are brazed or bolted. State the method and the flatness on mating faces.
- Cleanliness
- No smear, no embedded abrasive, no fingerprints on plated faces. Say how the part is packed.
Grades that fit
Published typical values for the alloy, never a promise from a shop. Each grade has its own reference page.
- C10100
Oxygen free electronic copperCleanest structure and best finish potential. Standard for demanding RF and for anything that is also in vacuum. - C11000
Electrolytic tough pitch copperFine for most waveguide and cavity work, cheaper and easier to source. - C14500
Tellurium copperThreaded fittings and connector bodies where the field does not touch the machined surface.
What drives the price
If a quote looks high, one of these is usually the reason, and most of them can be changed on the drawing.
- FinishEach step down in Ra on a field surface is a separate finishing pass, sometimes a separate process.
- Cavity accuracyInternal dimensions that set frequency need real tolerance and real inspection.
- Plating controlSilver thickness on the field face is a measured value, not a default.
- Multi piece assembliesBrazed cavities add a joint, a fixture and a leak or RF test.
What to put on the drawing
Send these and the quotes you receive will be comparable. The RFQ builder writes the material lines for you.
- Which faces carry the field, with Ra per face
- Cavity dimensions toleranced, outside dimensions relaxed
- Grade and no substitution note where it matters
- Plating spec with thickness on field faces stated separately
- Joining method and flatness on mating faces
- Packaging and handling requirement
Send the drawing
Short version here, or the full RFQ form with tolerance, finish and plating fields. Your files go only to the shops we match. Ask for an NDA and nothing moves until it is signed.
We are a matching service, not a machine shop. How matching works.
Questions buyers ask
Something else? Email .
Why does surface finish matter so much on RF copper parts?
Because current at high frequency runs in a very thin surface layer. Roughness lengthens the path and increases resistive loss. A finish that is fine mechanically can be poor electrically.
Should the whole part be finished to the field spec?
No. Name the faces that carry the field and finish those. Finishing the outside to the same Ra is money spent on nothing.
Is silver plating required?
Not always. It lowers surface resistance and is common on demanding parts. Specify it with thickness on the field face and a nickel barrier under it.
Can you match parts that are also vacuum components?
Yes. Say so in the RFQ, because it changes the grade to C10100 and adds vent hole, cleaning and packaging rules.