Copper & Brass FeCl₃

Chemical Etching Formula
C5102 phosphor bronze with FeCl₃

The FeCl₃ chemistry is a proven formula for C5102 phosphor bronze. This reference sheet lists the concentration (40 °Bé), specific gravity (1.380), bath temperature (46°C), and the full range of conveyor speeds and feature tolerances that result. Use it to size your process before committing to a production trial.

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
0.05-0.5 mm Thickness Range
0.20 mm Typical Thickness
0.12-2.77 m/min Conveyor Speed Range
0.40 m/min Typical Speed
60-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
9-91 μm Undercut Range
2.74 Etch Factor (EF)
97.4% Typical Yield (96.7-97.8%)

Why FeCl₃ for C5102 phosphor bronze?

On C5102 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 C5102 phosphor bronze etch line runs a variant of this formula.

Process Window & Bath Control

Hold the bath at 46°C with concentration 40 °Bé (specific gravity 1.380). Across the 0.05-0.5 mm thickness range, conveyor speed runs from 0.12-2.77 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.40 m/min for 0.20 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 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 9-91 μm, and the etch factor is about 2.74. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 60-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 9-91 μm
• Typical etch factor (EF): 2.74

Yield & Production Economics

This formula delivers a typical yield of 97.4% (range 96.7-97.8%). 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

C5102 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

Minimum producible hole diameter ranges 60-600 μm across the 0.05-0.5 mm thickness band, following the 1.2× material-thickness design rule. The smallest holes are only available on the thinnest stock; attempting holes below the floor for a given thickness causes yield to drop sharply.

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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