Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS316L with FeCl₃+HCl

The FeCl₃+HCl chemistry is a proven formula for SUS316L. 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
Half etch (single-sided) Etch Depth Type
0.1-0.3 mm Thickness Range
0.18 mm Typical Thickness
0.2-0.82 m/min Conveyor Speed Range
0.41 m/min Typical Speed
120-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
18-55 μm Undercut Range
2.75 Etch Factor (EF)
97.5% Typical Yield (97.2-97.6%)

Why FeCl₃+HCl for SUS316L?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS316L. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS316L is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Bath control for SUS316L in FeCl₃+HCl: temperature 48°C, concentration 45 °Bé, specific gravity 1.420. The recipe is tuned for half etch (single-sided). Conveyor speed is the primary throughput control, ranging 0.2-0.82 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 120-360 μm and the minimum line width ranges 100-300 μm across the 0.1-0.3 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 18-55 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: 120-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 18-55 μm
• Typical etch factor (EF): 2.75

Yield & Production Economics

This formula delivers a typical yield of 97.5% (range 97.2-97.6%). 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

Parts produced with the FeCl₃+HCl formula on SUS316L 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

Run the bath at 48°C. Holding much above 53°C can degrade photoresist adhesion and erode feature edges; running below 43°C slows the etch and forces a conveyor-speed reduction. Production lines hold 48°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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