Copper & Brass FeCl₃

Chemical Etching Formula
H65 brass with FeCl₃

The FeCl₃ chemistry is a proven formula for H65 brass. This reference sheet lists the concentration (36 °Bé), specific gravity (1.340), bath temperature (43°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
36 °Bé Concentration
1.340 Specific Gravity
43 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.01-0.04 mm Thickness Range
0.02 mm Typical Thickness
5.22-23.35 m/min Conveyor Speed Range
10.80 m/min Typical Speed
15-42 μm Min Hole Ø Range
100 μm Min Line Width Range
46059 μm Undercut Range
2.82 Etch Factor (EF)
98.8% Typical Yield (98.8%)

Why FeCl₃ for H65 brass?

On H65 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 H65 brass etch line runs a variant of this formula.

Process Window & Bath Control

The process window for this FeCl₃ formula centres on 43°C and 36 °Bé. Conveyor speed spans 5.22-23.35 m/min over the 0.01-0.04 mm thickness band; the typical operating point is 10.80 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 H65 brass at through etch (double-sided), plan for a minimum hole diameter in the 15-42 μm range and a minimum line width in the 100 μm range, depending on the chosen sheet thickness within 0.01-0.04 mm. The etch factor of ~2.82 and undercut range of 46059 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 15-42 μm
• Minimum line width range: 100 μm
• Single-side undercut range: 46059 μm
• Typical etch factor (EF): 2.82

Yield & Production Economics

Typical mass-production yield for H65 brass in the FeCl₃ system is 98.8%, within an observed range of 98.8%. 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

H65 brass 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

FeCl₃ balances oxidation rate, bath stability, and photoresist compatibility for H65 brass. More aggressive chemistries over-etch and roughen sidewalls; milder ones stall or attack the resist. This formula's concentration (36 °Bé) and 43°C bath keep the etch factor near 2.82 with predictable undercut.

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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