Chemical Etching Formula
SUS420
with FeCl₃+HCl
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.
Why FeCl₃+HCl for SUS420?
Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS420. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS420 is anisotropic etching with predictable undercut and an easily regenerated spent bath.
Process Window & Bath Control
The process window for this FeCl₃+HCl formula centres on 46°C and 42 °Bé. Conveyor speed spans 0.12-1.54 m/min over the 0.08-0.45 mm thickness band; the typical operating point is 0.37 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
Design rules for this recipe: hole diameter 96-540 μm, line width 100-450 μm, single-side undercut 14-80 μm — all as a function of thickness across 0.08-0.45 mm. The higher the etch factor (this formula holds about 2.80), the tighter the achievable tolerance. Below the minimum feature sizes, yield falls off steeply, so treat those numbers as hard floors rather than targets.
• Minimum hole diameter range: 96-540 μm
• Minimum line width range: 100-450 μm
• Single-side undercut range: 14-80 μm
• Typical etch factor (EF): 2.80
Yield & Production Economics
This formula delivers a typical yield of 97.2% (range 96.5-97.6%). 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 SUS420 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.
Frequently Asked Questions
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.