Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS303 with FeCl₃+HCl

Working with SUS303 on a chemical etch line begins with the right formula. The FeCl₃+HCl system documented below produces through etch (double-sided) across 0.1-0.3 mm sheet, with a minimum hole-diameter range of 120-360 μm and a minimum line-width range of 100-300 μm. The numbers scale with thickness — thinner stock yields finer features.

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
48 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.1-0.3 mm Thickness Range
0.20 mm Typical Thickness
0.2-1.05 m/min Conveyor Speed Range
0.37 m/min Typical Speed
120-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
18-54 μm Undercut Range
2.78 Etch Factor (EF)
96.6% Typical Yield (96.3-96.9%)

Why FeCl₃+HCl for SUS303?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS303. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS303 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 0.1-0.3 mm thickness range, conveyor speed runs from 0.2-1.05 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.37 m/min for 0.20 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 SUS303 at through etch (double-sided), plan for a minimum hole diameter in the 120-360 μm range and a minimum line width in the 100-300 μm range, depending on the chosen sheet thickness within 0.1-0.3 mm. The etch factor of ~2.78 and undercut range of 18-54 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 120-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 18-54 μm
• Typical etch factor (EF): 2.78

Yield & Production Economics

Expect a yield in the 96.3-96.9% range for SUS303 with FeCl₃+HCl, with 96.6% 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 SUS303 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

Yes. Wet chemical etching is a non-contact chemical process with no mechanical cutting or thermal input, so etched SUS303 features are completely free of burrs, work-hardening, and heat-affected zones. That edge quality is the defining advantage over stamping or laser cutting for precision flat parts.

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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