Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS304 with FeCl₃+HCl

Working with SUS304 on a chemical etch line begins with the right formula. The FeCl₃+HCl system documented below produces through etch (double-sided) across 0.01-0.45 mm sheet, with a minimum hole-diameter range of 8-540 μm and a minimum line-width range of 100-450 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
46 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.45 mm Thickness Range
0.02 mm Typical Thickness
0.12-74.85 m/min Conveyor Speed Range
14.40 m/min Typical Speed
8-540 μm Min Hole Ø Range
100-450 μm Min Line Width Range
1-80 μm Undercut Range
2.83 Etch Factor (EF)
98.5% Typical Yield (96.5-98.8%)

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

Bath control for SUS304 in FeCl₃+HCl: temperature 46°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 0.12-74.85 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

Design rules for this recipe: hole diameter 8-540 μm, line width 100-450 μm, single-side undercut 1-80 μm — all as a function of thickness across 0.01-0.45 mm. The higher the etch factor (this formula holds about 2.83), the tighter the achievable tolerance. Below the minimum feature sizes, yield falls off steeply, so treat those numbers as hard floors rather than targets.

Design Rule Summary
• Minimum hole diameter range: 8-540 μm
• Minimum line width range: 100-450 μm
• Single-side undercut range: 1-80 μm
• Typical etch factor (EF): 2.83

Yield & Production Economics

Typical mass-production yield for SUS304 in the FeCl₃+HCl system is 98.5%, within an observed range of 96.5-98.8%. 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.

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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