Guides / Sourcing
What Belongs on a PEEK Wafer Carrier Drawing
September 26, 2026
Sources: manufacturer datasheets and published standards. See editorial standards.
A wafer carrier or comb is a small part carrying a large amount of risk. It touches the product directly, it cycles through temperature changes many times over its life and a dimension that drifts by a fraction of a millimeter can misalign a wafer inside a tool that costs far more to stop than the part itself. Specifying one well means going past material and outline dimensions into the details that actually decide whether it survives.
Grade: usually CF30, sometimes not
Most carriers, forks and combs are carbon filled PEEK (CF30), for three properties that arrive together: static dissipation so charge does not build up near the wafer, a coefficient of thermal expansion around a third of unfilled PEEK so slots and fingers stay located through a temperature swing and better heat transfer than unfilled resin. Where the part needs to insulate electrically rather than dissipate charge, unfilled or glass filled PEEK is the right call instead, and that tradeoff is covered in CF30 vs GF30.
Finger and slot tolerance, not outside profile
The dimensions that decide whether a carrier works are the finger pitch, slot width and the thickness of whatever locates against the wafer edge. The outside profile of the part matters far less. A drawing that tolerances every dimension equally usually ends up either too expensive to quote competitively or too loose on the dimensions that matter, so put the tight tolerance where the wafer actually touches and leave the rest open.
| Feature | Typical target | Why it matters |
|---|---|---|
| Finger pitch | ±0.025 to ±0.05 mm | Sets wafer spacing and clearance inside the tool |
| Slot width | ±0.025 to ±0.05 mm | Controls how the wafer edge seats and how much it can shift |
| Locating thickness | ±0.05 mm | Determines stack height across a full cassette |
| Outside profile | ±0.1 mm or open | Rarely affects function, tightening it only adds cost |
General reasoning behind these ranges, and how they shift with part size and grade, is in PEEK machining tolerances.
Deburring: no metallic contamination, ever
A wafer carrier that measures correctly can still fail incoming inspection if a steel deburring brush or a dirty fixture left a metallic trace on it. Shops that regularly cut fab hardware keep dedicated non-metallic deburring tools, brass or nylon fixtures and separate work areas for this kind of part rather than running it through the same process as a general machining job. Ask for this explicitly rather than assuming a shop already does it, because most general-purpose machine shops do not.
Edge chamfers: for particles, not looks
Sharp edges on a wafer carrier are a particle source. Every corner that a wafer or a robot arm can catch on will eventually shed a small amount of material, and that material ends up somewhere in the tool. A light chamfer or radius on every edge that sees contact, specified on the drawing rather than left to shop discretion, removes most of that risk for very little added machining time.
Why annealing is not optional here
Machining removes material asymmetrically from a part that started as extruded or molded stock carrying internal stress, and that stress relaxes gradually after cutting. On a solid block that movement is invisible. On a comb with thin fingers and narrow slots, it shows up as fingers that were straight off the machine and out of tolerance a week later. Annealing before final sizing relieves most of that stress in a controlled way instead of letting it happen slowly in the field, which is exactly the failure mode covered in annealing PEEK parts.
Putting it on the RFQ
A wafer carrier drawing that gets a clean quote and a part that survives handling usually states:
- Grade, with CF30 as the default unless insulation is required
- Tight tolerance called out on finger pitch, slot width and locating thickness, with everything else left open
- Deburring method, stated as non-metallic
- Edge treatment on every contact surface
- Annealing before final sizing on any part with thin or narrow features
- Cleaning and packing requirements, since a carrier is going straight into a clean environment
None of this is unusual for a shop that already machines PEEK for this market. It is unusual for one that does not, and the questions above are a fast way to find out which one you are quoting.
Send the drawing with the tolerances and cleanliness requirements called out, and we match you with shops that already cut wafer handling hardware.
Frequently asked questions
What PEEK grade is normal for a wafer carrier or comb?
CF30 is the default for most wafer handling hardware, chosen for static dissipation near the wafer and for dimensional stability under repeated temperature cycling. Unfilled PEEK is used where electrical insulation matters more than charge dissipation.
Why does deburring matter more on a wafer carrier than on a typical machined part?
Any metallic residue left by a steel tool or a dirty fixture can transfer to a wafer on contact. Shops that work in this niche use dedicated non-metallic deburring tools and clean fixtures, and it is worth asking for that in writing.
Does a wafer carrier need to be annealed?
Usually yes, for anything with thin fingers or slots. Residual stress from machining relaxes over time and moves narrow features out of tolerance, and annealing before final sizing catches most of that movement before it reaches the customer.
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