Overview

Copper shim etching makes thin spacing, grounding and masking washers by chemically dissolving the outline out of copper strip rather than blanking it with a die, so the part stays flat, burr-free and free of the rolled edge that upsets a precision stack-up. A photoresist mask carries the outline and any internal slots, the exposed metal is removed in a matched etchant, and thickness is held as tightly as ±0.005 mm on stock from 0.02 mm to 1.0 mm. Feedstocks include C1100 tough-pitch copper, C1020 oxygen-free copper, beryllium copper and brass, chosen for conductivity, spring properties or solderability. Because the geometry comes from artwork, a new thickness or outline is a new film, and mixed part numbers can share one sheet without separate tooling.

For assembly and electronics buyers, copper shim etching replaces the slow, imprecise habit of hand-cutting foil or stacking ground spacers. A stamped washer carries burr and camber that change the clamped gap, while a laser-cut edge leaves dross and a heat tint on a conductive surface. Photochemical machining holds the outer contour to about ±0.02 mm, keeps both faces flat, and can half-etch fold lines, add alignment notches or print a thickness code in the same pass. The result is a repeatable, clean gap every time the assembly is rebuilt, which matters for motor air gaps, RF grounding and shielding stacks.

Parameter Window

• Available Materials: C1100 copper, C1020 oxygen-free copper, beryllium copper, brass
• Material Thickness Range: 0.02–1.0 mm
• Tolerance: ±0.005 mm on thickness, ±0.02 mm on outer contour
• Minimum Feature: 0.10 mm slot width, 0.15 mm hole diameter
• Surface Options: nickel, tin or silver plating, anti-oxidation treatment, anneal-softening
• Compliance: ISO 9001 process control, RoHS/REACH material traceability

Manufacturing Process / Workflow (8 Steps)

1. Artwork Review — Convert the washer drawing to vector art, verify slot and notch width against stock, and confirm thickness callout.
2. Material Selection — Pick C1100 for conductivity, C1020 for brazing, beryllium copper for spring temper, or brass for cost.
3. Cleaning & Lamination — Degrease the sheet and laminate dry-film resist under controlled heat so fine slots stay protected.
4. UV Exposure — Image the outline on both faces in registration so edges etch straight through the thickness.
5. Development — Wash out unexposed resist and inspect narrow slots for scumming before etching begins.
6. Etching — Spray etchant matched to the alloy; time, temperature and speed set edge quality and final thickness.
7. Stripping & Finishing — Remove resist, neutralize, then plate, passivate or anneal to the specified temper.
8. Inspection & Packaging — Gauge thickness, contour and flatness against the approved sample and pack flat between liners.

Core Advantages

1. Tight thickness control: Thickness held to ±0.005 mm gives a predictable clamped gap without hand sorting.
2. Burr-free flat parts: Chemical removal leaves no roll-over, so spacers seat flush and do not scratch mating faces.
3. Fine slots and notches: 0.10 mm slots and 0.15 mm holes hold cleanly even on 0.05 mm foil.
4. No die cost: A new outline is a new film, keeping prototype and revision work inexpensive.
5. Conductive clean surface: Edges are free of dross and heat tint, which protects grounding and solder wetting.
6. Mixed parts per sheet: Copper shim etching lets several thickness codes or outlines share one panel, reducing unit cost on small orders.

Typical Applications

• Gap-setting shims: Precision spacers for motor air gaps, gearboxes and bearing preload.
• RF grounding washers: Conductive copper washers that keep a low-impedance path under a fastener.
• EMI gasket spacers: Thin shims that set compression on shielding gaskets.
• Thermal spacers: Copper washers that control bond-line thickness in heat-sink stacks.
• Masking and shim stock: Half-etched fold lines for peelable or adjustable masks.
• Mould and fixture shims: Flat, burr-free packers for tool alignment and height setting.

Design Notes & Process Considerations

1. Slot width versus thickness: Keep the narrowest slot at no less than 1.2 × stock thickness to avoid closure during etch.
2. Thickness tolerance: State whether tolerance applies to bare copper or after plating, since plating adds to the stack.
3. Half-etch fold lines: Give the residual land thickness and bend direction for any peelable or foldable feature.
4. Flatness: Call out flatness per 100 mm when the shim is clamped in a precision assembly.
5. Temper and plating: Specify annealed or spring temper and name the plating system to preserve conductivity.
6. Panel layout: Copper shim etching benefits from grouping part numbers on one sheet with common registration to protect contour accuracy.