Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS420 with FeCl₃+HCl

For engineers selecting an etching chemistry for SUS420, the FeCl₃+HCl formula shown here defines the bath composition, temperature window, and achievable feature sizes across a 0.03-0.5 mm thickness band. Typical mass-production yield for this recipe is 97.0%, with a typical conveyor speed of 0.50 m/min at 48°C.

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
42 °Bé Concentration
1.390 Specific Gravity
48 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.03-0.5 mm Thickness Range
0.18 mm Typical Thickness
0.12-6.69 m/min Conveyor Speed Range
0.50 m/min Typical Speed
36-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
5-89 μm Undercut Range
2.80 Etch Factor (EF)
97.0% Typical Yield (96-97.4%)

Why FeCl₃+HCl for SUS420?

On SUS420, 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 SUS420 etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃+HCl formula centres on 48°C and 42 °Bé. Conveyor speed spans 0.12-6.69 m/min over the 0.03-0.5 mm thickness band; the typical operating point is 0.50 m/min. Every 5°C drop in bath temperature requires roughly a 30% reduction in conveyor speed to hold the same etch depth, so temperature stability is the single biggest lever on consistency.

Design Rules & Tolerances

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 36-600 μm and the minimum line width ranges 100-500 μm across the 0.03-0.5 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 5-89 μm, and the etch factor is about 2.80. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 36-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 5-89 μm
• Typical etch factor (EF): 2.80

Yield & Production Economics

This formula delivers a typical yield of 97.0% (range 96-97.4%). 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

Typical applications for SUS420 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

Across the supported 0.03-0.5 mm thickness range, conveyor speed runs from 0.12-6.69 m/min. A typical mid-range setpoint is 0.50 m/min for 0.18 mm stock. Thinner sheets run faster and thicker sheets slower, roughly in inverse proportion to thickness.

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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