Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS304 with FeCl₃+HCl

This reference describes how SUS304 responds to the FeCl₃+HCl etching formula. At a bath temperature of 47°C and concentration of 44 °Bé, the recipe holds an etch factor of about 2.82 and a typical production yield of 98.3%. It is intended as engineering reference data for design, sourcing, and process planning.

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.

FeCl₃+HCl Etchant System
44 °Bé Concentration
1.410 Specific Gravity
47 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.02-0.08 mm Thickness Range
0.04 mm Typical Thickness
1.54-12.3 m/min Conveyor Speed Range
4.35 m/min Typical Speed
24-96 μm Min Hole Ø Range
100 μm Min Line Width Range
46126 μm Undercut Range
2.82 Etch Factor (EF)
98.3% Typical Yield (98.1-98.4%)

Why FeCl₃+HCl for SUS304?

On SUS304, 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 SUS304 etch line runs a variant of this formula.

Process Window & Bath Control

Hold the bath at 47°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.02-0.08 mm thickness range, conveyor speed runs from 1.54-12.3 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 4.35 m/min for 0.04 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 24-96 μm and the minimum line width ranges 100 μm across the 0.02-0.08 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 46126 μm, and the etch factor is about 2.82. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 24-96 μm
• Minimum line width range: 100 μm
• Single-side undercut range: 46126 μm
• Typical etch factor (EF): 2.82

Yield & Production Economics

Expect a yield in the 98.1-98.4% range for SUS304 with FeCl₃+HCl, with 98.3% 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 SUS304 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.

More Stainless Steel Formulas

Other formulas in the same material family.

AM350 Stainless Steel FeCl₃+HCl Through etch (double-sided) SUS2205 Duplex Stainless FeCl₃+HCl Through etch (double-sided) SUS2507 Super Duplex FeCl₃+HCl Through etch (double-sided) SUS301 FeCl₃+HCl Through etch (double-sided) SUS301 FeCl₃+HCl Through etch (double-sided) SUS302 FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Typical inspection on SUS304 etched with FeCl₃+HCl includes optical checks for unetched residue and surface defects, dimensional metrology on critical features, and edge-quality assessment. Final dimensional tolerance is usually ±10% of the smallest critical feature or ±25 μm, whichever is larger.

Need a Quote for This Process?

WET Etched runs production wet chemical etching lines using the FeCl₃+HCl chemistry. Send us your part drawing and quantity for a full process quote.

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