Nickel Superalloys FeCl₃+HCl

Chemical Etching Formula
Inconel 625 with FeCl₃+HCl

For engineers selecting an etching chemistry for Inconel 625, the FeCl₃+HCl formula shown here defines the bath composition, temperature window, and achievable feature sizes across a 0.01-0.5 mm thickness band. Typical mass-production yield for this recipe is 95.5%, with a typical conveyor speed of 0.70 m/min at 54°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
46 °Bé Concentration
1.430 Specific Gravity
54 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.5 mm Thickness Range
0.10 mm Typical Thickness
0.12-47.63 m/min Conveyor Speed Range
0.70 m/min Typical Speed
8-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
1-101 μm Undercut Range
2.48 Etch Factor (EF)
95.5% Typical Yield (94.3-95.8%)

Why FeCl₃+HCl for Inconel 625?

On Inconel 625, 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 Inconel 625 etch line runs a variant of this formula.

Process Window & Bath Control

Hold the bath at 54°C with concentration 46 °Bé (specific gravity 1.430). Across the 0.01-0.5 mm thickness range, conveyor speed runs from 0.12-47.63 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.70 m/min for 0.10 mm stock. Use redundant PID temperature control to hold the bath within ±1.5°C, and titrate at least once per shift.

Design Rules & Tolerances

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 8-600 μm and the minimum line width ranges 100-500 μm across the 0.01-0.5 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 1-101 μm, and the etch factor is about 2.48. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 8-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 1-101 μm
• Typical etch factor (EF): 2.48

Yield & Production Economics

This formula delivers a typical yield of 95.5% (range 94.3-95.8%). 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 Inconel 625 are common in turbine-engine seals, high-temperature gaskets, and aerospace fluidic plates. 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 Nickel Superalloys Formulas

Other formulas in the same material family.

Hastelloy C-22 FeCl₃+HCl Through etch (double-sided) Hastelloy C-276 FeCl₃+HCl Through etch (double-sided) Hastelloy X FeCl₃+HCl Through etch (double-sided) Inconel 600 FeCl₃+HCl Through etch (double-sided) Inconel 601 FeCl₃+HCl Through etch (double-sided) Inconel 690 FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

The recommended working concentration for Inconel 625 in the FeCl₃+HCl system is 46 °Bé, corresponding to a specific gravity of about 1.430. Titrate the bath at least once per shift and correct back toward this setpoint; drift below it signals depletion, while drift above usually means evaporative water loss.

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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