Carbon & Tool Steel FeCl₃+HCl

Chemical Etching Formula
SK3 Tool Steel with FeCl₃+HCl

For engineers selecting an etching chemistry for SK3 Tool Steel, the FeCl₃+HCl formula shown here defines the bath composition, temperature window, and achievable feature sizes across a 0.1-0.5 mm thickness band. Typical mass-production yield for this recipe is 96.3%, with a typical conveyor speed of 0.27 m/min at 50°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
44 °Bé Concentration
1.410 Specific Gravity
50 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.1-0.5 mm Thickness Range
0.25 mm Typical Thickness
0.12-0.98 m/min Conveyor Speed Range
0.27 m/min Typical Speed
120-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
19-93 μm Undercut Range
2.70 Etch Factor (EF)
96.3% Typical Yield (95.5-96.7%)

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.

Design Rule Summary
• 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.

More Carbon & Tool Steel Formulas

Other formulas in the same material family.

50CrV4 Spring Steel FeCl₃+HCl Through etch (double-sided) 65Mn Spring Steel FeCl₃+HCl Through etch (double-sided) 65Mn Spring Steel FeCl₃+HCl Half etch (single-sided) DT4 pure iron FeCl₃+HCl Through etch (double-sided) SK2 Tool Steel FeCl₃+HCl Through etch (double-sided) SK5 Tool Steel FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Single-side undercut ranges 19-93 μm depending on thickness and dwell time. When sizing the photomask for a finished feature on SK3 Tool Steel, subtract twice the expected undercut from the target width so the etched dimension lands on specification.

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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