Chemical Etching
The Fotofab Process of photochemical machining (often abbreviated as PCM, and sometimes referred to as chemical milling or chemical etching) is a technique for manufacturing high-precision flat metal parts. By chemically etching away the unwanted materials, a photographically prepared mask (a Phototool) is used to protect the metal that is to remain after the etching process.
The following ten steps comprise our photochemical machining process:
1. Order review
We don't take it if we can't make it precisely to your requirements.
2. Phototooling
• CAD image laser-plotted to 1/4 mil resolution
• Two-sided working phototool registered within .0005"
3. Metal stock
• Certification
• Lot control for traceability
4. Metal preparation
• Degrease and rinse
• Acid wash, scrub and dry
• Inspect for cleanliness
5. Coating
• Photo resist bonded to metal
• Exit temperature controlled
6. Ultraviolet exposure
• Polymerizes the resist
• Light controlled by Stouffer 21 step-tablet
7. Developing
• Developer solution heated to 85F
• Photo resist on unexposed surfaces dissolved
• Visual break-point test at halfway point
• Thorough rinsing and air drying
8. Etching
• Acid etchant sprayed on both surfaces simultaneously
• Speed varied per metal and thickness
• Top and bottom metal removal variable if desired
• Speed, specific gravity, pH, O.R.P. and etchant temperature charted
and adjusted as needed
9. Stripping
• Alkaline wash removes photo resist
• Parts exit conveyorized stripper-drier free of water spots
10. Final inspection
• Finished parts compared to blueprint
• Inspection equipment calibrated to NBS
• Perfect parts securely packaged and shipped via your chosen carrier
Contact us or visit our Design Guide To Photochemical Machining to understand the flexibility this unique process offers you before or while you begin designing your parts.
