Titanium Alloys HF(5%)+HNO₃(30%)

Chemical Etching Formula
Ti-3Al-2.5V with HF(5%)+HNO₃(30%)

This page documents the reference wet chemical etching formula for Ti-3Al-2.5V using the HF(5%)+HNO₃(30%) system. The recipe below covers a sheet-thickness range of 0.05-0.5 mm and is configured for through etch (double-sided). Every value is drawn from operational process records rather than theoretical calculation, and is provided as a starting point for your own process development.

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(5%)+HNO₃(30%) Etchant System
— °Bé Concentration
1.190 Specific Gravity
34 °C Bath Temperature
Through etch (double-sided) Etch Depth Type
0.05-0.5 mm Thickness Range
0.18 mm Typical Thickness
0.12-1.36 m/min Conveyor Speed Range
0.17 m/min Typical Speed
60-600 μm Min Hole Ø Range
100-500 μm Min Line Width Range
11-109 μm Undercut Range
2.30 Etch Factor (EF)
95.1% Typical Yield (94.2-95.4%)

Why HF(5%)+HNO₃(30%) for Ti-3Al-2.5V?

Hydrofluoric/nitric formulas are used for refractory and titanium-family metals such as Ti-3Al-2.5V 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 Ti-3Al-2.5V there is rarely a practical alternative.

Process Window & Bath Control

The process window for this HF(5%)+HNO₃(30%) formula centres on 34°C and as specified. Conveyor speed spans 0.12-1.36 m/min over the 0.05-0.5 mm thickness band; the typical operating point is 0.17 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

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 11-109 μm, and the etch factor is about 2.30. 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: 11-109 μm
• Typical etch factor (EF): 2.30

Yield & Production Economics

Typical mass-production yield for Ti-3Al-2.5V in the HF(5%)+HNO₃(30%) system is 95.1%, within an observed range of 94.2-95.4%. 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

Typical applications for Ti-3Al-2.5V processed with HF(5%)+HNO₃(30%) include medical implants, surgical instruments, aerospace brackets, and corrosion-resistant filters. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.

More Titanium Alloys Formulas

Other formulas in the same material family.

TA1 commercially pure titanium HF(5%)+HNO₃(30%) Through etch (double-sided) TA1 commercially pure titanium HF(5%)+HNO₃(30%) Through etch (double-sided) TA1 commercially pure titanium HF(5%)+HNO₃(30%) Half etch (single-sided) Ta1 Pure Tantalum HF(8%)+HNO₃(30%) Through etch (double-sided) TA2 commercially pure titanium HF(5%)+HNO₃(30%) Through etch (double-sided) TA3 commercially pure titanium HF(5%)+HNO₃(30%) Through etch (double-sided)

Frequently Asked Questions

Single-side undercut ranges 11-109 μm depending on thickness and dwell time. When sizing the photomask for a finished feature on Ti-3Al-2.5V, 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 HF(5%)+HNO₃(30%) chemistry. Send us your part drawing and quantity for a full process quote.

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