Copper & Brass FeCl₃

Chemical Etching Formula
C5191 phosphor bronze with FeCl₃

Working with C5191 phosphor bronze on a chemical etch line begins with the right formula. The FeCl₃ system documented below produces through etch (double-sided) across 0.01-0.5 mm sheet, with a minimum hole-diameter range of 8-600 μm and a minimum line-width range of 100-500 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 Etchant System
40 °Bé Concentration
1.380 Specific Gravity
46 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.5 mm Thickness Range
0.09 mm Typical Thickness
0.12-71.44 m/min Conveyor Speed Range
1.33 m/min Typical Speed
8-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
1-91 μm Undercut Range
2.75 Etch Factor (EF)
97.9% Typical Yield (96.7-98.2%)

Why FeCl₃ for C5191 phosphor bronze?

On C5191 phosphor bronze, 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 C5191 phosphor bronze etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃ formula centres on 46°C and 40 °Bé. Conveyor speed spans 0.12-71.44 m/min over the 0.01-0.5 mm thickness band; the typical operating point is 1.33 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 C5191 phosphor bronze at through etch (double-sided), plan for a minimum hole diameter in the 8-600 μm range and a minimum line width in the 100-500 μm range, depending on the chosen sheet thickness within 0.01-0.5 mm. The etch factor of ~2.75 and undercut range of 1-91 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 8-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 1-91 μm
• Typical etch factor (EF): 2.75

Yield & Production Economics

Typical mass-production yield for C5191 phosphor bronze in the FeCl₃ system is 97.9%, within an observed range of 96.7-98.2%. 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

C5191 phosphor bronze etched with this recipe typically ends up in lead frames, busbars, flexible heater elements, RF gaskets, and precision electrical contacts. 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 Copper & Brass Formulas

Other formulas in the same material family.

C1020 OF Copper FeCl₃ Through etch (double-sided) C1100 T2 copper FeCl₃ Through etch (double-sided) C1100 T2 copper FeCl₃ Through etch (double-sided) C1100 T2 copper FeCl₃ Through etch (double-sided) C1100 T2 copper FeCl₃ Through etch (double-sided) C1100 T2 copper FeCl₃ Half etch (single-sided)

Frequently Asked Questions

Yes. The FeCl₃ chemistry and 46°C bath are identical from a single prototype part up to full production — the chemistry does not depend on quantity. Conveyor speed stays in the 0.12-71.44 m/min range. Only the per-part economics shift, since fixed photomask and setup costs dominate at low volumes.

Need a Quote for This Process?

WET Etched runs production wet chemical etching lines using the FeCl₃ chemistry. Send us your part drawing and quantity for a full process quote.

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