Copper & Brass FeCl₃

Chemical Etching Formula
QBe2 with FeCl₃

This reference describes how QBe2 responds to the FeCl₃ etching formula. At a bath temperature of 48°C and concentration of 42 °Bé, the recipe holds an etch factor of about 2.78 and a typical production yield of 97.4%. It is intended as engineering reference data for design, sourcing, and process planning.

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
42 °Bé Concentration
1.390 Specific Gravity
48 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.05-0.3 mm Thickness Range
0.15 mm Typical Thickness
0.21-2.64 m/min Conveyor Speed Range
0.69 m/min Typical Speed
60-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
9-54 μm Undercut Range
2.78 Etch Factor (EF)
97.4% Typical Yield (97-97.7%)

Why FeCl₃ for QBe2?

On QBe2, 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 QBe2 etch line runs a variant of this formula.

Process Window & Bath Control

Bath control for QBe2 in FeCl₃: temperature 48°C, concentration 42 °Bé, specific gravity 1.390. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.21-2.64 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

Feature sizes scale with sheet thickness. For this formula the minimum hole diameter ranges 60-360 μm and the minimum line width ranges 100-300 μm across the 0.05-0.3 mm band, following the industry 1.2× (hole) and 1.0× (line) thickness rules. Single-side undercut ranges 9-54 μm, and the etch factor is about 2.78. Size your photomask by subtracting twice the expected undercut from each finished feature dimension.

Design Rule Summary
• Minimum hole diameter range: 60-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 9-54 μm
• Typical etch factor (EF): 2.78

Yield & Production Economics

Typical mass-production yield for QBe2 in the FeCl₃ system is 97.4%, within an observed range of 97-97.7%. 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

Parts produced with the FeCl₃ formula on QBe2 are common in lead frames, busbars, flexible heater elements, RF gaskets, and precision electrical contacts. The burr-free, stress-free nature of chemical etching makes it the preferred process wherever flatness and edge quality matter more than raw throughput.

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

The typical etch factor for this recipe is 2.78 — vertical etch depth is about 2.78× the single-side undercut. Higher EF means tighter feature tolerance; values near or above 3.0 are close to best-in-class for wet etching, and QBe2 in FeCl₃ sits in the typical production range.

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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