Chemical Etching Formula
Kovar alloy with FeCl₃+HCl

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.

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.

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.

Process Equipment & Material Reference

Process equipment for the Kovar alloy / FeCl₃+HCl combination is built around our biomedical blade etching machine platform — closed-loop temperature control, redundant pump headers, and metering for bath replenishment all directly affect the etch factor and yield numbers cited on this page.

Related to this formula, the Kovar chemical etching guide page documents the full process envelope for the same alloy family, including pre-treatment chemistry and post-etch inspection criteria.

Production Use Cases for This Formula

Production examples for the Kovar alloy / FeCl₃+HCl recipe span high-speed air-intake mesh for hair dryers, custom thin-film heating elements, and electronic thin-film component etching. In every case, the etch factor and undercut figures on this page are the dominant tolerance drivers — bath maintenance discipline matters more than equipment headline rating.

Designs that sit slightly outside this thickness or feature-size envelope are usually addressable by a sister formula in the same etchant family. The bath chemistry stays the same; the tuning shifts to conveyor speed and resist choice.

Other Metals Etched with FeCl₃+HCl

The FeCl₃+HCl chemistry is also documented for these alloys.

More Precision Alloys Formulas

Other formulas in the same material family.

Frequently Asked Questions