Chemical Etching Formula
SUS304
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 SUS304?
On SUS304, 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 SUS304 etch line runs a variant of this formula.
Process Window & Bath Control
Bath control for SUS304 in FeCl₃+HCl: temperature 48°C, concentration 44 °Bé, specific gravity 1.410. The recipe is tuned for half etch (single-sided). Conveyor speed is the primary throughput control, ranging 74.85 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
Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 8 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 2.80. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.
• Minimum hole diameter range: 8 μm
• Minimum line width range: 100 μm
• Single-side undercut range: 1 μm
• Typical etch factor (EF): 2.80
Yield & Production Economics
Expect a yield in the 97.8% range for SUS304 with FeCl₃+HCl, with 97.8% typical on a well-controlled line. Most rejects trace back to upstream coating and exposure rather than to the etch bath itself, so tightening photolithography control is usually the fastest path to a higher number.
Typical Applications
Parts produced with the FeCl₃+HCl formula on SUS304 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.
Process Equipment & Material Reference
On the shop floor, this SUS304 + FeCl₃+HCl recipe is implemented on a precision acid cleaning machine. The 48°C bath setpoint and 74.85 m/min conveyor range correspond to verified production envelopes on that equipment for half etch (single-sided).
If you need a wider view of stainless beyond this single recipe, our Stainless Steel chemical etching guide covers grade selection, photoresist compatibility, and typical industries that consume this metal in etched form.
Production Use Cases for This Formula
Typical end-uses for SUS304 run on this formula include electronic thin-film component etching, cold-press juicer filtration mesh, and mobile-phone earpiece mesh. The 48°C bath and 0.01 mm supported thickness range cover most of the production work in these segments without re-tuning chemistry.
Adjacent applications usually transfer onto this same formula with no chemistry change, sometimes only a conveyor speed tweak. Drop a drawing and a target volume and we will return a process card built off the parameters on this page.
More Stainless Steel Formulas
Other formulas in the same material family.
Frequently Asked Questions
Sources & References
- ASTM E407: Standard Practice for Microetching Metals and Alloys
- ASTM B912: Standard Specification for Passivation of Stainless Steels
- Photo Chemical Machining Institute — process capability guidelines
- NIST Engineering Statistics Handbook — process tolerance and capability
Standards are referenced for context. Always confirm parameters against the current published edition and your own process validation.
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.