Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS420J2 with FeCl₃+HCl

Working with SUS420J2 on a chemical etch line begins with the right formula. The FeCl₃+HCl system documented below produces through etch (double-sided) across 0.1-0.5 mm sheet, with a minimum hole-diameter range of 120-600 μm and a minimum line-width range of 100-500 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
50 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.1-0.5 mm Thickness Range
0.25 mm Typical Thickness
0.12-1.08 m/min Conveyor Speed Range
0.30 m/min Typical Speed
120-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
18-91 μm Undercut Range
2.75 Etch Factor (EF)
96.7% Typical Yield (95.9-97.1%)

Why FeCl₃+HCl for SUS420J2?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS420J2. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS420J2 is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Bath control for SUS420J2 in FeCl₃+HCl: temperature 50°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 0.12-1.08 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

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 120-600 μm and the minimum line width ranges 100-500 μm across the 0.1-0.5 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 18-91 μm, and the etch factor is about 2.75. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 120-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 18-91 μm
• Typical etch factor (EF): 2.75

Yield & Production Economics

Typical mass-production yield for SUS420J2 in the FeCl₃+HCl system is 96.7%, within an observed range of 95.9-97.1%. 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

SUS420J2 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

Run the bath at 50°C. Holding much above 55°C can degrade photoresist adhesion and erode feature edges; running below 45°C slows the etch and forces a conveyor-speed reduction. Production lines hold 50°C within ±1.5°C using redundant PID control.

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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