Copper & Brass FeCl₃

Chemical Etching Formula
H68 brass with FeCl₃

The FeCl₃ chemistry is a proven formula for H68 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
0.05-0.5 mm Thickness Range
0.18 mm Typical Thickness
0.12-3.11 m/min Conveyor Speed Range
0.56 m/min Typical Speed
60-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
9-89 μm Undercut Range
2.81 Etch Factor (EF)
97.8% Typical Yield (97-98.1%)

Why FeCl₃ for H68 brass?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like H68 brass. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on H68 brass is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Bath control for H68 brass in FeCl₃: temperature 43°C, concentration 36 °Bé, specific gravity 1.340. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.12-3.11 m/min across the supported thickness range. Check specific gravity each shift with a calibrated hydrometer and correct with fresh make-up or water as needed.

Design Rules & Tolerances

Design rules for this recipe: hole diameter 60-600 μm, line width 100-500 μm, single-side undercut 9-89 μm — all as a function of thickness across 0.05-0.5 mm. The higher the etch factor (this formula holds about 2.81), the tighter the achievable tolerance. Below the minimum feature sizes, yield falls off steeply, so treat those numbers as hard floors rather than targets.

Design Rule Summary
• Minimum hole diameter range: 60-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 9-89 μm
• Typical etch factor (EF): 2.81

Yield & Production Economics

Expect a yield in the 97-98.1% range for H68 brass with FeCl₃, with 97.8% typical on a well-controlled line. Most rejects trace back to upstream coating and exposure rather than to the etch bath itself, so tightening photolithography control is usually the fastest path to a higher number.

Typical Applications

H68 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

Single-side undercut ranges 9-89 μm depending on thickness and dwell time. When sizing the photomask for a finished feature on H68 brass, subtract twice the expected undercut from the target width so the etched dimension lands on specification.

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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