Chemical Etching Formula
SPCC Cold-Rolled Steel
with FeCl₃
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.
Why FeCl₃ for SPCC Cold-Rolled Steel?
On SPCC Cold-Rolled Steel, 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 SPCC Cold-Rolled Steel etch line runs a variant of this formula.
Process Window & Bath Control
Hold the bath at 46°C with concentration 42 °Bé (specific gravity 1.390). Across the 0.01-0.5 mm thickness range, conveyor speed runs from 0.12-78.25 m/min — thinner sheets move faster, thicker sheets slower, in roughly inverse proportion to thickness. A typical mid-range setpoint is 0.89 m/min for 0.13 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
Design rules for this recipe: hole diameter 8-600 μm, line width 100-500 μm, single-side undercut 1-91 μm — all as a function of thickness across 0.01-0.5 mm. The higher the etch factor (this formula holds about 2.75), the tighter the achievable tolerance. Below the minimum feature sizes, yield falls off steeply, so treat those numbers as hard floors rather than targets.
• Minimum hole diameter range: 8-600 μm
• Minimum line width range: 100-500 μm
• Single-side undercut range: 1-91 μm
• Typical etch factor (EF): 2.75
Yield & Production Economics
Typical mass-production yield for SPCC Cold-Rolled Steel in the FeCl₃ system is 97.3%, within an observed range of 96.3-97.6%. 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 SPCC Cold-Rolled Steel processed with FeCl₃ include spring elements, blades, shim stock, and stamped-replacement flat parts. The formula's tolerance band and yield make it well suited to medium-to-high-volume precision flat parts.
Process Equipment & Material Reference
On the shop floor, this SPCC Cold-Rolled Steel + FeCl₃ recipe is implemented on a wet chemical etching machine. The 46°C bath setpoint and 0.12-78.25 m/min conveyor range correspond to verified production envelopes on that equipment for through etch (double-sided).
The Steel chemical etching guide reference goes one level above the recipe shown here, surveying the full thickness range, depth options, and common subgrades we run for steel.
Production Use Cases for This Formula
Production examples for the SPCC Cold-Rolled Steel / FeCl₃ recipe span ultrasonic mesh for robotic vacuum cleaners, stainless steel mesh for aroma diffusers, and soy-milk-maker filtration mesh. In every case, the etch factor and undercut figures on this page are the dominant tolerance drivers — bath maintenance discipline matters more than equipment headline rating.
If your part falls into one of these classes — or a closely adjacent one — this formula is usually the right starting point. We confirm fit with a short sample run on the actual sheet stock before locking in mask artwork.
More Carbon & Tool Steel Formulas
Other formulas in the same material family.
Frequently Asked Questions
Sources & References
- ASTM E407: Standard Practice for Microetching Metals and Alloys
- ASTM B912: Standard Specification for Passivation of Stainless Steels
- Photo Chemical Machining Institute — process capability guidelines
- NIST Engineering Statistics Handbook — process tolerance and capability
Standards are referenced for context. Always confirm parameters against the current published edition and your own process validation.
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.