Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS316 with FeCl₃+HCl

The FeCl₃+HCl chemistry is a proven formula for SUS316. This reference sheet lists the concentration (45 °Bé), specific gravity (1.420), bath temperature (48°C), and the full range of conveyor speeds and feature tolerances that result. Use it to size your process before committing to a production trial.

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
45 °Bé Concentration
1.420 Specific Gravity
48 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.08-0.45 mm Thickness Range
0.22 mm Typical Thickness
0.12-1.54 m/min Conveyor Speed Range
0.37 m/min Typical Speed
96-540 μm Min Hole Ø Range
100-450 μm Min Line Width Range
15-83 μm Undercut Range
2.72 Etch Factor (EF)
97.2% Typical Yield (96.5-97.6%)

Why FeCl₃+HCl for SUS316?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS316. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS316 is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Bath control for SUS316 in FeCl₃+HCl: temperature 48°C, concentration 45 °Bé, specific gravity 1.420. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.12-1.54 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 96-540 μm and the minimum line width ranges 100-450 μm across the 0.08-0.45 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 15-83 μm, and the etch factor is about 2.72. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 96-540 μm
• Minimum line width range: 100-450 μm
• Single-side undercut range: 15-83 μm
• Typical etch factor (EF): 2.72

Yield & Production Economics

Expect a yield in the 96.5-97.6% range for SUS316 with FeCl₃+HCl, with 97.2% 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 SUS316 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

This formula is documented for a sheet-thickness range of 0.08-0.45 mm, with a typical value of 0.22 mm. Outside this band the same chemistry may still work, but conveyor speed and feature tolerances should be re-verified with a sample run before production.

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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