Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS316L with FeCl₃+HCl

This page documents the reference wet chemical etching formula for SUS316L using the FeCl₃+HCl system. The recipe below covers a sheet-thickness range of 0.01 mm and is configured for half etch (single-sided). Every value is drawn from operational process records rather than theoretical calculation, and is provided as a starting point for your own process development.

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
50 °C Bath Temperature
Half etch (single-sided) Etch Depth Type
0.01 mm Thickness Range
0.01 mm Typical Thickness
44.19 m/min Conveyor Speed Range
44.19 m/min Typical Speed
10 μm Min Hole Ø Range
100 μm Min Line Width Range
1 μm Undercut Range
2.73 Etch Factor (EF)
97.5% Typical Yield (97.5%)

Why FeCl₃+HCl for SUS316L?

On SUS316L, the ferric chloride system attacks the alloy's oxide layer continuously while ferric ions drive dissolution. It is regenerable, compatible with standard photolithography, and produces clean burr-free edges — which is why nearly every SUS316L etch line runs a variant of this formula.

Process Window & Bath Control

Bath control for SUS316L in FeCl₃+HCl: temperature 50°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 44.19 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 10 μm and the minimum line width ranges 100 μm across the 0.01 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 1 μm, and the etch factor is about 2.73. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 10 μm
• Minimum line width range: 100 μm
• Single-side undercut range: 1 μm
• Typical etch factor (EF): 2.73

Yield & Production Economics

Typical mass-production yield for SUS316L in the FeCl₃+HCl system is 97.5%, within an observed range of 97.5%. 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

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

Yes. The FeCl₃+HCl chemistry and 50°C bath are identical from a single prototype part up to full production — the chemistry does not depend on quantity. Conveyor speed stays in the 44.19 m/min range. Only the per-part economics shift, since fixed photomask and setup costs dominate at low volumes.

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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