Stainless Steel FeCl₃+HCl

Chemical Etching Formula
SUS302 with FeCl₃+HCl

For engineers selecting an etching chemistry for SUS302, the FeCl₃+HCl formula shown here defines the bath composition, temperature window, and achievable feature sizes across a 0.05-0.3 mm thickness band. Typical mass-production yield for this recipe is 97.4%, with a typical conveyor speed of 0.75 m/min at 48°C.

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+HCl Etchant System
44 °Bé Concentration
1.410 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
0.21-3.11 m/min Conveyor Speed Range
0.75 m/min Typical Speed
60-360 μm Min Hole Ø Range
100-300 μm Min Line Width Range
9-53 μm Undercut Range
2.82 Etch Factor (EF)
97.4% Typical Yield (96.9-97.6%)

Why FeCl₃+HCl for SUS302?

Ferric-chloride-based formulas are the industrial workhorse for ferrous, nickel, and copper-bearing alloys like SUS302. The Fe³⁺ ion oxidizes the metal surface; where HCl is present it regenerates dissolved species and stabilizes chloride concentration. The result on SUS302 is anisotropic etching with predictable undercut and an easily regenerated spent bath.

Process Window & Bath Control

Hold the bath at 48°C with concentration 44 °Bé (specific gravity 1.410). Across the 0.05-0.3 mm thickness range, conveyor speed runs from 0.21-3.11 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.75 m/min for 0.15 mm stock. Use redundant PID temperature control to hold the bath within ±1.5°C, and titrate at least once per shift.

Design Rules & Tolerances

When laying out artwork for SUS302 at through etch (double-sided), plan for a minimum hole diameter in the 60-360 μm range and a minimum line width in the 100-300 μm range, depending on the chosen sheet thickness within 0.05-0.3 mm. The etch factor of ~2.82 and undercut range of 9-53 μm determine how much the mask must be biased to land the finished dimension on target.

Design Rule Summary
• Minimum hole diameter range: 60-360 μm
• Minimum line width range: 100-300 μm
• Single-side undercut range: 9-53 μm
• Typical etch factor (EF): 2.82

Yield & Production Economics

Expect a yield in the 96.9-97.6% range for SUS302 with FeCl₃+HCl, with 97.4% 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

Typical applications for SUS302 processed with FeCl₃+HCl include precision shims, encoder discs, RF/EMI shields, surgical and dental components, fuel-cell bipolar plates, and fine filter meshes. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.

More Stainless Steel Formulas

Other formulas in the same material family.

AM350 Stainless Steel FeCl₃+HCl Through etch (double-sided) SUS2205 Duplex Stainless FeCl₃+HCl Through etch (double-sided) SUS2507 Super Duplex FeCl₃+HCl Through etch (double-sided) SUS301 FeCl₃+HCl Through etch (double-sided) SUS301 FeCl₃+HCl Through etch (double-sided) SUS303 FeCl₃+HCl Through etch (double-sided)

Frequently Asked Questions

As a rule of thumb, etch rate roughly doubles for every 10°C of temperature rise. From the 48°C setpoint, dropping to 43°C roughly halves the rate while rising to 53°C roughly doubles it. The practical operating window is bounded by photoresist limits rather than by the etchant itself.

Need a Quote for This Process?

WET Etched runs production wet chemical etching lines using the FeCl₃+HCl chemistry. Send us your part drawing and quantity for a full process quote.

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