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 48°C and concentration of 44 °Bé, the recipe holds an etch factor of about 2.80 and a typical production yield of 97.7%. 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
48 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.5 mm Thickness Range
0.10 mm Typical Thickness
0.12-48.61 m/min Conveyor Speed Range
1.10 m/min Typical Speed
10-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
1-89 μm Undercut Range
2.80 Etch Factor (EF)
97.7% Typical Yield (96.5-97.9%)

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 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 0.12-48.61 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 10-600 μm, line width 100-500 μm, single-side undercut 1-89 μm — all as a function of thickness across 0.01-0.5 mm. The higher the etch factor (this formula holds about 2.80), 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: 10-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 1-89 μm
• Typical etch factor (EF): 2.80

Yield & Production Economics

This formula delivers a typical yield of 97.7% (range 96.5-97.9%). At that rate, per-part economics are driven mostly by fixed photomask and setup cost for small batches and by sheet utilisation for large runs. The chemistry itself does not change with quantity, so the same recipe serves prototype and production volumes.

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

Minimum line width ranges 100-500 μm over the supported thickness range, per the 1.0× thickness rule. At the fine end, photoresist resolution and adhesion — not the etchant — become the limiting factors, so resist selection matters as much as bath chemistry.

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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