Chemical Etching Formula
SUS302 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 SUS302?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS302. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS302 is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Hold the bath at 48°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.05-0.3 mm thickness range, conveyor speed runs from 0.21-3.11 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.75 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

When laying out artwork for SUS302 at through etch (double-sided), plan for a minimum hole diameter in the 60-360 μm range and a minimum line width in the 100-300 μm range, depending on the chosen sheet thickness within 0.05-0.3 mm. The etch factor of ~2.82 and undercut range of 9-53 μm determine how much the mask must be biased to land the finished dimension on target.

Yield & Production Economics

Expect a yield in the 96.9-97.6% range for SUS302 with FeCl₃+HCl, with 97.4% typical on a well-controlled line. Most rejects trace back to upstream coating and exposure rather than to the etch bath itself, so tightening photolithography control is usually the fastest path to a higher number.

Typical Applications

Typical applications for SUS302 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 SUS302 / FeCl₃+HCl combination is built around our precision acid cleaning 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.

The Stainless Steel chemical etching guide reference goes one level above the recipe shown here, surveying the full thickness range, depth options, and common subgrades we run for stainless.

Production Use Cases for This Formula

Parts produced with this SUS302 + FeCl₃+HCl formula end up in a wide range of finished products. Representative production runs we have completed using this exact recipe family include cold-press juicer filtration mesh, juicer filtration mesh etching, and stainless steel metal filter mesh. Each case shares the same root sensitivity: clean photoresist edges, a tightly held bath SG of 1.410, and a conveyor speed inside the 0.21-3.11 m/min envelope.

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