Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS304L with FeCl₃+HCl

This page documents the reference wet chemical etching formula for SUS304L using the FeCl₃+HCl system. The recipe below covers a sheet-thickness range of 0.03-0.5 mm and is configured for through etch (double-sided). Every value is drawn from operational process records rather than theoretical calculation, and is provided as a starting point for your own process development.

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
0.03-0.5 mm Thickness Range
0.18 mm Typical Thickness
0.12-6.69 m/min Conveyor Speed Range
0.50 m/min Typical Speed
36-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
5-89 μm Undercut Range
2.81 Etch Factor (EF)
97.4% Typical Yield (96.4-97.8%)

Why FeCl₃+HCl for SUS304L?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS304L. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS304L is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Bath control for SUS304L in FeCl₃+HCl: temperature 48°C, concentration 44 °Bé, specific gravity 1.410. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.12-6.69 m/min across the supported thickness range. Check specific gravity each shift with a calibrated hydrometer and correct with fresh make-up or water as needed.

Design Rules & Tolerances

When laying out artwork for SUS304L at through etch (double-sided), plan for a minimum hole diameter in the 36-600 μm range and a minimum line width in the 100-500 μm range, depending on the chosen sheet thickness within 0.03-0.5 mm. The etch factor of ~2.81 and undercut range of 5-89 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 36-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 5-89 μm
• Typical etch factor (EF): 2.81

Yield & Production Economics

Expect a yield in the 96.4-97.8% range for SUS304L 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

Parts produced with the FeCl₃+HCl formula on SUS304L are common in precision shims, encoder discs, RF/EMI shields, surgical and dental components, fuel-cell bipolar plates, and fine filter meshes. The burr-free, stress-free nature of chemical etching makes it the preferred process wherever flatness and edge quality matter more than raw throughput.

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

Single-side undercut ranges 5-89 μm depending on thickness and dwell time. When sizing the photomask for a finished feature on SUS304L, subtract twice the expected undercut from the target width so the etched dimension lands on specification.

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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