Precision Alloys FeCl₃+HCl

Chemical Etching Formula
Kovar alloy with FeCl₃+HCl

For engineers selecting an etching chemistry for Kovar alloy, the FeCl₃+HCl formula shown here defines the bath composition, temperature window, and achievable feature sizes across a 0.01 mm thickness band. Typical mass-production yield for this recipe is 97.0%, with a typical conveyor speed of 30.36 m/min at 50°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
44 °Bé Concentration
1.410 Specific Gravity
50 °C Bath Temperature
Half etch (single-sided) Etch Depth Type
0.01 mm Thickness Range
0.01 mm Typical Thickness
30.36 m/min Conveyor Speed Range
30.36 m/min Typical Speed
12 μm Min Hole Ø Range
100 μm Min Line Width Range
2 μm Undercut Range
2.75 Etch Factor (EF)
97.0% Typical Yield (97%)

Why FeCl₃+HCl for Kovar alloy?

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

Process Window & Bath Control

Hold the bath at 50°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.01 mm thickness range, conveyor speed runs from 30.36 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 30.36 m/min for 0.01 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 12 μm and the minimum line width ranges 100 μm across the 0.01 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 2 μm, and the etch factor is about 2.75. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 12 μm
• Minimum line width range: 100 μm
• Single-side undercut range: 2 μm
• Typical etch factor (EF): 2.75

Yield & Production Economics

Typical mass-production yield for Kovar alloy in the FeCl₃+HCl system is 97.0%, within an observed range of 97%. 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

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

Across the supported 0.01 mm thickness range, conveyor speed runs from 30.36 m/min. A typical mid-range setpoint is 30.36 m/min for 0.01 mm stock. Thinner sheets run faster and thicker sheets slower, roughly in inverse proportion to thickness.

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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