Photo Etched Stainless Steel Ultra Thin Foil Shims 0.03mm-0.6mm for Precision Gap Control

Photo Etched Stainless Steel Foil Shims, 0.03 mm to 0.6 mm

A foil shim is the part that closes a gap measured in hundredths of a millimetre. It is usually the least expensive item in an assembly, but it decides whether the assembly seats square, whether a lens keeps its air gap and whether a bearing runs with the right preload. This page covers shims etched from stainless steel foil between 0.03 mm and 0.6 mm, produced to the customer's own drawing.

What a foil gauge changes

Below about 0.6 mm the sheet behaves like foil. It sags under its own weight, it distorts when a punch or a chuck presses on it, and it marks easily. Photo chemical etching suits this gauge because the cut is made by chemistry from both faces at once: no press force, no clamping pressure and no cutter touches the part. The outline, holes and slots come from artwork applied to the sheet, so the same artwork can be re-run when a dimension changes, and the shim keeps the thickness of the foil it was etched from.

Where thin shims do their work

• Sensor and lens modules: setting the air gap between an optical element and its housing, or between a sensor and a bracket.
• Electronic assemblies: taking up clearance under connectors, shields, spacers and board supports.
• Medical instruments: thin spacers and locating shims inside hand tools, diagnostic units and single use devices.
• Small mechanisms: preload and backlash adjustment in gears, levers, spring packs and pivots.
• Fixtures and automation: alignment shims where a burr or a thickness step would appear as run-out rather than as a cosmetic defect.

Edges, faces and flatness

Etching removes material from both faces at the same time, so the edge finishes without roll-over and without a grinding burr. There is no deburring step afterwards, which matters for foil: a hand deburr on 0.05 mm sheet bends the part as often as it cleans it, and a burr pushed back onto the seating face changes the effective thickness of the shim.

One face also keeps the finish of the incoming foil, because nothing is ground or coined against it. That face is normally the one placed against the machined surface, so the shim seats on the same texture the foil had when it was rolled.

Thin foil with a large open area can bow after etching. Open area, foil thickness and part outline are therefore reviewed together, flatness is agreed on the drawing, and parts are handled flat through the line and packed on a rigid support.

Where a part has to be identified after assembly, a shallow etched mark such as a part number, a thickness figure or a lot code can be produced in the same etching pass, instead of printing, labelling or laser marking a part that is too thin for a laser mark to stay legible.

Materials and finishing

SUS304 is the usual choice for general use, SUS316L where corrosion resistance matters, and copper alloys, beryllium copper, phosphor bronze or nickel where conductivity, spring properties or solderability are required. Finishing follows the application: passivation for stainless parts, electropolishing where a smoother edge and surface are wanted, or selective nickel, gold, tin or silver plating. Plating adds to the part thickness and has to be masked where contact areas must stay bare, so the plated area and the thickness are agreed on the drawing before the run.

Specification

Checks carried out on each lot

• Outline, hole and slot dimensions measured against the drawing
• Thickness measured on the finished shim, not only on the incoming foil
• Visual check for incomplete etching, residual resist, staining and edge condition
• Flatness check where the drawing calls for it
• Plating thickness and appearance where a finish is specified
• Quantity and packing check before dispatch

What to send with an enquiry

A drawing with the outline and feature dimensions, the material grade, the foil thickness, the tolerance required on profile and on thickness, any flatness requirement, the surface finish, the first order quantity and the destination. Price and timing follow from those details, because part size, feature density, foil gauge and finishing route each change the etching and handling work. Every shim is made to the customer's own specification, so this page describes the process rather than a fixed offer.

Send a drawing in DXF, DWG, PDF or STEP format and our team will review the part and come back with the questions needed to quote it.