Carbon & Tool Steel FeCl₃+HCl

Chemical Etching Formula
65Mn Spring Steel with FeCl₃+HCl

This page documents the reference wet chemical etching formula for 65Mn Spring Steel using the FeCl₃+HCl system. The recipe below covers a sheet-thickness range of 0.01 mm and is configured for half etch (single-sided). Every value is drawn from operational process records rather than theoretical calculation, and is provided as a starting point for your own process development.

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
48 °C Bath Temperature
Half etch (single-sided) Etch Depth Type
0.01 mm Thickness Range
0.01 mm Typical Thickness
47.73 m/min Conveyor Speed Range
47.73 m/min Typical Speed
10 μm Min Hole Ø Range
100 μm Min Line Width Range
1 μm Undercut Range
2.72 Etch Factor (EF)
97.4% Typical Yield (97.4%)

Why FeCl₃+HCl for 65Mn Spring Steel?

On 65Mn Spring 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 65Mn Spring Steel etch line runs a variant of this formula.

Process Window & Bath Control

Bath control for 65Mn Spring Steel 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 47.73 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 65Mn Spring Steel at half etch (single-sided), plan for a minimum hole diameter in the 10 μm range and a minimum line width in the 100 μm range, depending on the chosen sheet thickness within 0.01 mm. The etch factor of ~2.72 and undercut range of 1 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 10 μm
• Minimum line width range: 100 μm
• Single-side undercut range: 1 μm
• Typical etch factor (EF): 2.72

Yield & Production Economics

This formula delivers a typical yield of 97.4% (range 97.4%). 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

Typical applications for 65Mn Spring Steel processed with FeCl₃+HCl include spring elements, blades, shim stock, and stamped-replacement flat parts. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.

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) DT4 pure iron FeCl₃+HCl Through etch (double-sided) SK2 Tool Steel FeCl₃+HCl Through etch (double-sided) SK3 Tool Steel FeCl₃+HCl Through etch (double-sided) SK5 Tool Steel FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

This formula is documented for a sheet-thickness range of 0.01 mm, with a typical value of 0.01 mm. Outside this band the same chemistry may still work, but conveyor speed and feature tolerances should be re-verified with a sample run before production.

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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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