Chemical Etching Formula
SUS304 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 SUS304?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS304. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS304 is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Hold the bath at 46°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.01-0.5 mm thickness range, conveyor speed runs from 0.12-68.04 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.50 m/min for 0.15 mm stock. Use redundant PID temperature control to hold the bath within ±1.5°C, and titrate at least once per shift.

Design Rules & Tolerances

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 8-600 μm and the minimum line width ranges 100-500 μm across the 0.01-0.5 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 1-89 μm, and the etch factor is about 2.82. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Yield & Production Economics

Typical mass-production yield for SUS304 in the FeCl₃+HCl system is 97.8%, within an observed range of 97.2-98.2%. The dominant yield-loss modes are photoresist pinhole defects and rinse-water contamination. Improving incoming sheet quality and photoresist coating consistency gives the highest yield-improvement leverage for this formula.

Typical Applications

SUS304 etched with this recipe typically ends up in precision shims, encoder discs, RF/EMI shields, surgical and dental components, fuel-cell bipolar plates, and fine filter meshes. Because chemical etching applies no mechanical or thermal load, the finished features are free of work-hardening and heat-affected zones — a decisive advantage over stamping or laser cutting for these uses.

Process Equipment & Material Reference

Process equipment for the SUS304 / 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 electronic thin-film component etching, juicer filtration mesh etching, and stainless steel metal filter mesh. These applications share thin-feature geometries that benefit from the predictable etch factor near 2.82 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