Precision Alloys FeCl₃+HCl

Chemical Etching Formula
Kovar alloy with FeCl₃+HCl

Working with Kovar alloy on a chemical etch line begins with the right formula. The FeCl₃+HCl system documented below produces through etch (double-sided) across 0.01-0.3 mm sheet, with a minimum hole-diameter range of 8-360 μm and a minimum line-width range of 100-300 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+HCl Etchant System
44 °Bé Concentration
1.410 Specific Gravity
50 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.3 mm Thickness Range
0.02 mm Typical Thickness
0.18-65.32 m/min Conveyor Speed Range
12.10 m/min Typical Speed
8-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
1-55 μm Undercut Range
2.76 Etch Factor (EF)
97.5% Typical Yield (96.1-98.2%)

Why FeCl₃+HCl for Kovar alloy?

On Kovar alloy, 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 Kovar alloy etch line runs a variant of this formula.

Process Window & Bath Control

Hold the bath at 50°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.01-0.3 mm thickness range, conveyor speed runs from 0.18-65.32 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 12.10 m/min for 0.02 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

Design rules for this recipe: hole diameter 8-360 μm, line width 100-300 μm, single-side undercut 1-55 μm — all as a function of thickness across 0.01-0.3 mm. The higher the etch factor (this formula holds about 2.76), 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: 8-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 1-55 μm
• Typical etch factor (EF): 2.76

Yield & Production Economics

This formula delivers a typical yield of 97.5% (range 96.1-98.2%). 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

Kovar alloy etched with this recipe typically ends up in hermetic sealing rings, lead frames matched to glass/ceramic, and magnetic shielding. 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 Precision Alloys Formulas

Other formulas in the same material family.

1J22 Iron-Cobalt Alloy FeCl₃+HCl Through etch (double-sided) 1J46 Permalloy FeCl₃+HCl Through etch (double-sided) 1J50 Permalloy FeCl₃+HCl Through etch (double-sided) 1J79 Permalloy FeCl₃+HCl Through etch (double-sided) 1J85 Super-Permalloy FeCl₃+HCl Through etch (double-sided) HyMu80 (Permalloy) FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

Yes. Wet chemical etching is a non-contact chemical process with no mechanical cutting or thermal input, so etched Kovar alloy features are completely free of burrs, work-hardening, and heat-affected zones. That edge quality is the defining advantage over stamping or laser cutting for precision flat parts.

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.

Request a Quote Browse Formulas