Tantalum HF(8%)+HNO₃(30%)

Chemical Etching Formula
Ta-2.5W Tantalum Alloy with HF(8%)+HNO₃(30%)

Working with Ta-2.5W Tantalum Alloy on a chemical etch line begins with the right formula. The HF(8%)+HNO₃(30%) system documented below produces through etch (double-sided) across 0.05-0.3 mm sheet, with a minimum hole-diameter range of 60-360 μm and a minimum line-width range of 100-300 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.

HF(8%)+HNO₃(30%) Etchant System
— °Bé Concentration
1.220 Specific Gravity
40 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.05-0.3 mm Thickness Range
0.15 mm Typical Thickness
0.12-0.87 m/min Conveyor Speed Range
0.19 m/min Typical Speed
60-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
11-69 μm Undercut Range
2.18 Etch Factor (EF)
92.7% Typical Yield (92.2-92.9%)

Why HF(8%)+HNO₃(30%) for Ta-2.5W Tantalum Alloy?

Hydrofluoric/nitric formulas are used for refractory and titanium-family metals such as Ta-2.5W Tantalum Alloy because the fluoride ion is one of the few species that will break down their tenacious passive oxide. The nitric component oxidizes the freshly exposed metal so the fluoride can keep working. Handling demands are high, but for Ta-2.5W Tantalum Alloy there is rarely a practical alternative.

Process Window & Bath Control

Bath control for Ta-2.5W Tantalum Alloy in HF(8%)+HNO₃(30%): temperature 40°C, concentration as specified, specific gravity 1.220. The recipe is tuned for through etch (double-sided). Conveyor speed is the primary throughput control, ranging 0.12-0.87 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 60-360 μm, line width 100-300 μm, single-side undercut 11-69 μm — all as a function of thickness across 0.05-0.3 mm. The higher the etch factor (this formula holds about 2.18), 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: 60-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 11-69 μm
• Typical etch factor (EF): 2.18

Yield & Production Economics

This formula delivers a typical yield of 92.7% (range 92.2-92.9%). 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

Parts produced with the HF(8%)+HNO₃(30%) formula on Ta-2.5W Tantalum Alloy are common in implantable electronics, capacitor anodes, and chemical-process components. The burr-free, stress-free nature of chemical etching makes it the preferred process wherever flatness and edge quality matter more than raw throughput.

Frequently Asked Questions

Minimum producible hole diameter ranges 60-360 μm across the 0.05-0.3 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 HF(8%)+HNO₃(30%) chemistry. Send us your part drawing and quantity for a full process quote.

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