Chemical Etching Formula
SK3 Tool Steel
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 SK3 Tool Steel?
On SK3 Tool Steel, 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 SK3 Tool Steel etch line runs a variant of this formula.
Process Window & Bath Control
Bath control for SK3 Tool Steel in FeCl₃+HCl: temperature 50°C, concentration 44 °Bé, specific gravity 1.410. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.12-0.98 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
Design rules for this recipe: hole diameter 120-600 μm, line width 100-500 μm, single-side undercut 19-93 μm — all as a function of thickness across 0.1-0.5 mm. The higher the etch factor (this formula holds about 2.70), 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: 120-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 19-93 μm
• Typical etch factor (EF): 2.70
Yield & Production Economics
This formula delivers a typical yield of 96.3% (range 95.5-96.7%). 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 SK3 Tool Steel are common in spring elements, blades, shim stock, and stamped-replacement flat parts. 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
This SK3 Tool Steel formula is part of the standard process library running on our wet chemical etching machine. The same chemistry can be ported to any horizontal spray-etching line of comparable nozzle layout and bath-titration discipline.
Related to this formula, the Steel chemical etching guide page documents the full process envelope for the same alloy family, including pre-treatment chemistry and post-etch inspection criteria.
Production Use Cases for This Formula
Across the markets we serve, the FeCl₃+HCl formula on this page is most often deployed for stainless steel shower-head filter mesh, juicer filtration mesh etching, and automotive horn mesh etching. These applications share thin-feature geometries that benefit from the predictable etch factor near 2.70 and the low single-side undercut documented above.
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 Carbon & Tool 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.