Nickel Superalloys FeCl₃+HCl

Chemical Etching Formula
Inconel 601 with FeCl₃+HCl

This page documents the reference wet chemical etching formula for Inconel 601 using the FeCl₃+HCl system. The recipe below covers a sheet-thickness range of 0.1-0.3 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
46 °Bé Concentration
1.430 Specific Gravity
52 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.1-0.3 mm Thickness Range
0.20 mm Typical Thickness
0.12-0.65 m/min Conveyor Speed Range
0.21 m/min Typical Speed
120-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
20-60 μm Undercut Range
2.50 Etch Factor (EF)
94.9% Typical Yield (94.6-95.2%)

Why FeCl₃+HCl for Inconel 601?

On Inconel 601, 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 601 etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃+HCl formula centres on 52°C and 46 °Bé. Conveyor speed spans 0.12-0.65 m/min over the 0.1-0.3 mm thickness band; the typical operating point is 0.21 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

When laying out artwork for Inconel 601 at through etch (double-sided), plan for a minimum hole diameter in the 120-360 μm range and a minimum line width in the 100-300 μm range, depending on the chosen sheet thickness within 0.1-0.3 mm. The etch factor of ~2.50 and undercut range of 20-60 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 120-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 20-60 μm
• Typical etch factor (EF): 2.50

Yield & Production Economics

Typical mass-production yield for Inconel 601 in the FeCl₃+HCl system is 94.9%, within an observed range of 94.6-95.2%. The dominant yield-loss modes are photoresist pinhole defects and rinse-water contamination. Improving incoming sheet quality and photoresist coating consistency gives the highest yield-improvement leverage for this formula.

Typical Applications

Typical applications for Inconel 601 processed with FeCl₃+HCl include turbine-engine seals, high-temperature gaskets, and aerospace fluidic plates. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.

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 625 FeCl₃+HCl Through etch (double-sided) Inconel 690 FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Minimum line width ranges 100-300 μm over the supported thickness range, per the 1.0× thickness rule. At the fine end, photoresist resolution and adhesion — not the etchant — become the limiting factors, so resist selection matters as much as bath chemistry.

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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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