Chemical Etching Formula
SUS420 with FeCl₃+HCl

Formula Summary

The table below summarizes every parameter that defines this etching formula. Values listed as ranges scale with sheet thickness across the supported band.

Why FeCl₃+HCl for SUS420?

On SUS420, the ferric chloride system attacks the alloy's oxide layer continuously while ferric ions drive dissolution. It is regenerable, compatible with standard photolithography, and produces clean burr-free edges — which is why nearly every SUS420 etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃+HCl formula centres on 48°C and 42 °Bé. Conveyor speed spans 0.12-6.69 m/min over the 0.03-0.5 mm thickness band; the typical operating point is 0.50 m/min. Every 5°C drop in bath temperature requires roughly a 30% reduction in conveyor speed to hold the same etch depth, so temperature stability is the single biggest lever on consistency.

Design Rules & Tolerances

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 36-600 μm and the minimum line width ranges 100-500 μm across the 0.03-0.5 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 5-89 μm, and the etch factor is about 2.80. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Yield & Production Economics

This formula delivers a typical yield of 97.0% (range 96-97.4%). At that rate, per-part economics are driven mostly by fixed photomask and setup cost for small batches and by sheet utilisation for large runs. The chemistry itself does not change with quantity, so the same recipe serves prototype and production volumes.

Typical Applications

Typical applications for SUS420 processed with FeCl₃+HCl include precision shims, encoder discs, RF/EMI shields, surgical and dental components, fuel-cell bipolar plates, and fine filter meshes. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.

Process Equipment & Material Reference

Process equipment for the SUS420 / FeCl₃+HCl combination is built around our wet chemical etching machine platform — closed-loop temperature control, redundant pump headers, and metering for bath replenishment all directly affect the etch factor and yield numbers cited on this page.

If you need a wider view of stainless beyond this single recipe, our Stainless Steel chemical etching guide covers grade selection, photoresist compatibility, and typical industries that consume this metal in etched form.

Production Use Cases for This Formula

Across the markets we serve, the FeCl₃+HCl formula on this page is most often deployed for juicer filtration mesh etching, cold-press juicer filtration mesh, and stainless filtration mesh for vacuum cleaners. These applications share thin-feature geometries that benefit from the predictable etch factor near 2.80 and the low single-side undercut documented above.

Designs that sit slightly outside this thickness or feature-size envelope are usually addressable by a sister formula in the same etchant family. The bath chemistry stays the same; the tuning shifts to conveyor speed and resist choice.

Other Metals Etched with FeCl₃+HCl

The FeCl₃+HCl chemistry is also documented for these alloys.

More Stainless Steel Formulas

Other formulas in the same material family.

Frequently Asked Questions