Chemical Etching Formula
H90 brass with FeCl₃

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 for H90 brass?

On H90 brass, 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 H90 brass etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃ formula centres on 42°C and 34 °Bé. Conveyor speed spans 0.12-3.11 m/min over the 0.05-0.5 mm thickness band; the typical operating point is 0.56 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

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 60-600 μm and the minimum line width ranges 100-500 μm across the 0.05-0.5 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 9-88 μm, and the etch factor is about 2.85. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Yield & Production Economics

Typical mass-production yield for H90 brass in the FeCl₃ system is 97.8%, within an observed range of 97-98.1%. 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 H90 brass processed with FeCl₃ include lead frames, busbars, flexible heater elements, RF gaskets, and precision electrical contacts. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.

Process Equipment & Material Reference

This H90 brass formula is part of the standard process library running on our wet chemical etching machine. The same chemistry can be ported to any horizontal spray-etching line of comparable nozzle layout and bath-titration discipline.

For a broader treatment of the material itself — alloy variants, surface preparation, and process limits across thickness ranges — see our Brass chemical etching guide. That overview complements the formula-specific bath and conveyor data on this page.

Production Use Cases for This Formula

Parts produced with this H90 brass + FeCl₃ formula end up in a wide range of finished products. Representative production runs we have completed using this exact recipe family include cold-press juicer filtration mesh, stainless steel shower-head filter mesh, and soy-milk-maker filtration mesh. Each case shares the same root sensitivity: clean photoresist edges, a tightly held bath SG of 1.320, and a conveyor speed inside the 0.12-3.11 m/min envelope.

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

The FeCl₃ chemistry is also documented for these alloys.

More Copper & Brass Formulas

Other formulas in the same material family.

Frequently Asked Questions