Nickel Superalloys FeCl₃+HCl

Chemical Etching Formula
Inconel 718 with FeCl₃+HCl

This page documents the reference wet chemical etching formula for Inconel 718 using the FeCl₃+HCl system. The recipe below covers a sheet-thickness range of 0.01-0.5 mm and is configured for through etch (double-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
48 °Bé Concentration
1.450 Specific Gravity
56 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.5 mm Thickness Range
0.04 mm Typical Thickness
0.12-44.23 m/min Conveyor Speed Range
3.49 m/min Typical Speed
8-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
1-102 μm Undercut Range
2.45 Etch Factor (EF)
95.5% Typical Yield (94-96%)

Why FeCl₃+HCl for Inconel 718?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like Inconel 718. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on Inconel 718 is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Hold the bath at 56°C with concentration 48 °Bé (specific gravity 1.450). Across the 0.01-0.5 mm thickness range, conveyor speed runs from 0.12-44.23 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 3.49 m/min for 0.04 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

When laying out artwork for Inconel 718 at through etch (double-sided), plan for a minimum hole diameter in the 8-600 μm range and a minimum line width in the 100-500 μm range, depending on the chosen sheet thickness within 0.01-0.5 mm. The etch factor of ~2.45 and undercut range of 1-102 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 8-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 1-102 μm
• Typical etch factor (EF): 2.45

Yield & Production Economics

Expect a yield in the 94-96% range for Inconel 718 with FeCl₃+HCl, with 95.5% 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

Parts produced with the FeCl₃+HCl formula on Inconel 718 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 625 FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Both standard dry-film photoresists (typically 1.5–2.0 mil) and aqueous-developable liquid resists are compatible with FeCl₃+HCl at 56°C. Resist choice is driven by resolution: features near the fine end of the 100-500 μm line-width range usually call for liquid resist, while larger features can use lower-cost dry film.

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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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