Invar Chemical Etching — Engineering Reference
Wet chemical etching of Invar is a precision subtractive process that defines fine features by selectively dissolving the metal through a photoresist-patterned mask. On Invar specifically, the etchant choice, bath temperature, and conveyor speed combine to set the etch factor, undercut, and yield envelope every production run lives in.
Why Wet Chemical Etching for Invar?
Compared to laser, stamping, or wire EDM, wet chemical etching imparts no mechanical or thermal load to Invar. The process is parallel — every feature on a sheet etches simultaneously — so feature count has no impact on tooling cost. For Invar parts with hundreds or thousands of micro-features per piece, that is the dominant economic argument.
- Burr-free, stress-free edges — no post-deburring on Invar required.
- Tooling cost flat with feature complexity — only the photomask changes.
- Fast prototype iteration — artwork edits, not tool re-cuts.
- Tight tolerance on thin gauge Invar (down to ±25 μm in production).
- Compatible with downstream passivation, plating, electropolishing.
Process Window for Invar
Production lines etching Invar run a closed-loop temperature band of typically ±1.5 °C, with bath specific gravity monitored each shift via hydrometer or refractometer. Conveyor speed inversely tracks sheet thickness: thinner stock runs faster, thicker stock slower, with the goal of holding etch factor (EF) above 2.5 and single-side undercut below thirty microns wherever possible. For Invar, the recommended chemistry is FeCl₃+HCl.
| Recommended etchant | FeCl₃+HCl |
|---|---|
| Bath temperature window | 40 – 55 °C (chemistry-dependent) |
| Specific gravity setpoint | 1.30 – 1.45 g/cm³ for ferric chloride systems |
| Conveyor speed range | 0.4 – 8.0 m/min (thickness-dependent) |
| Typical etch factor (EF) | 2.5 – 3.0 |
| Single-side undercut | 5 – 40 μm depending on depth and thickness |
| Minimum hole diameter | ≈ 1.2× sheet thickness |
| Minimum line width | ≈ 1.0× sheet thickness |
| Mass-production yield | 95 – 99% on mature recipes for Invar |
Common Applications for Chemically Etched Invar
Across the markets we serve, chemically etched Invar is most often deployed in filtration meshes, lead frames and connector blanks, surgical and consumer blades, EMI shielding gaskets, heat-dissipation vents, and decorative architectural pieces. Thickness and feature complexity push different applications onto different recipes.
Related Recipes & Process Parameters
Every formula and parameter row below is a live page on this site with the full chemistry, conveyor speed, and tolerance window for the exact material-thickness-etchant combination. These are the references our process engineers cite from on production shifts.
Related Material References
Related Production Applications
Related Process Equipment
Frequently Asked Questions
What edge quality can I expect when etching Invar?
Wet chemical etching is non-contact, so etched Invar parts are completely burr-free, stress-free, and free of any heat-affected zone. Final edge cleanliness depends on photoresist adhesion and rinse cascade discipline.
Can you etch Invar on both sides simultaneously?
Yes. Our standard process is double-sided spray etching on Invar, with independent top and bottom nozzle banks. This is what allows through-etching of intricate filtration and lead-frame geometries in a single conveyor pass.
How is bath chemistry maintained over a production shift on Invar?
The FeCl₃+HCl bath is titrated at shift start and replenished with concentrated stock + water based on specific-gravity drift. Spent bath is regenerated electrolytically where possible.
Which etchant works best for Invar?
The recommended starting chemistry is FeCl₃+HCl. It balances etch rate, bath stability, and photoresist compatibility for Invar across the production thickness range.
Frequently Asked Questions
Can Wet Chemical Etching Invar be customised to my drawing?
Yes. Wet Chemical Etching Invar is made to order from your CAD/artwork, so dimensions, features and material are all tailored to your specification.
What is the typical lead time and minimum order for Wet Chemical Etching Invar?
Because etching needs no hard tooling, Wet Chemical Etching Invar can be prototyped quickly and scaled to volume. Share your drawing and quantity and we will advise lead time.
Which industries use Wet Chemical Etching Invar?
Wet Chemical Etching Invar is used across electronics, medical, automotive, aerospace and industrial filtration — anywhere precise, burr-free thin-metal parts are required.
What is Wet Chemical Etching Invar and how is it made?
Wet Chemical Etching Invar is produced by photochemical etching — a process that uses a patterned resist and etchant to remove metal precisely, with no mechanical stress or burrs.