Carbon & Tool Steel FeCl₃

Chemical Etching Formula
SPHC Hot-Rolled Steel with FeCl₃

Working with SPHC Hot-Rolled Steel on a chemical etch line begins with the right formula. The FeCl₃ system documented below produces through etch (double-sided) across 0.1-0.5 mm sheet, with a minimum hole-diameter range of 120-600 μm and a minimum line-width range of 100-500 μm. The numbers scale with thickness — thinner stock yields finer features.

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 Etchant System
40 °Bé Concentration
1.380 Specific Gravity
46 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.1-0.5 mm Thickness Range
0.25 mm Typical Thickness
0.12-1.12 m/min Conveyor Speed Range
0.31 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)
96.7% Typical Yield (96-97%)

Why FeCl₃ for SPHC Hot-Rolled Steel?

On SPHC Hot-Rolled 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 SPHC Hot-Rolled Steel etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃ formula centres on 46°C and 40 °Bé. Conveyor speed spans 0.12-1.12 m/min over the 0.1-0.5 mm thickness band; the typical operating point is 0.31 m/min. Every 5°C drop in bath temperature requires roughly a 30% reduction in conveyor speed to hold the same etch depth, so temperature stability is the single biggest lever on consistency.

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

Expect a yield in the 96-97% range for SPHC Hot-Rolled Steel with FeCl₃, with 96.7% 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

SPHC Hot-Rolled Steel etched with this recipe typically ends up in spring elements, blades, shim stock, and stamped-replacement flat parts. Because chemical etching applies no mechanical or thermal load, the finished features are free of work-hardening and heat-affected zones — a decisive advantage over stamping or laser cutting for these uses.

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) SK3 Tool Steel FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Standard pre-treatment is degrease, micro-etch to activate the surface, rinse, photoresist lamination or coating, UV exposure through the artwork, and develop. Pre-treatment quality directly drives yield for SPHC Hot-Rolled Steel: poor degreasing causes resist adhesion failures that show up as random pinhole defects in the etched pattern.

Need a Quote for This Process?

WET Etched runs production wet chemical etching lines using the FeCl₃ chemistry. Send us your part drawing and quantity for a full process quote.

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