Chemical Etching Formula
SUS329 Duplex Stainless
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 SUS329 Duplex Stainless?
Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS329 Duplex Stainless. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS329 Duplex Stainless is anisotropic etching with predictable undercut and an easily regenerated spent bath.
Process Window & Bath Control
Bath control for SUS329 Duplex Stainless in FeCl₃+HCl: temperature 54°C, concentration 46 °Bé, specific gravity 1.430. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.12-0.85 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
When laying out artwork for SUS329 Duplex Stainless at through etch (double-sided), plan for a minimum hole diameter in the 120-600 μm range and a minimum line width in the 100-500 μm range, depending on the chosen sheet thickness within 0.1-0.5 mm. The etch factor of ~2.55 and undercut range of 20-98 μm determine how much the mask must be biased to land the finished dimension on target.
• Minimum hole diameter range: 120-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 20-98 μm
• Typical etch factor (EF): 2.55
Yield & Production Economics
Typical mass-production yield for SUS329 Duplex Stainless in the FeCl₃+HCl system is 95.8%, within an observed range of 95-96.2%. 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
Typical applications for SUS329 Duplex Stainless 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.
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.