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Photo Chemical Etching

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The Fotofab Process of photo chemical etching, sometimes referred to as photochemical machining (PCM) or chemical milling, is a technique for manufacturing high-precision flat metal parts. During photo chemical etching, a photographically prepared mask (a Phototool) is used to protect the metal that is to remain after the chemical milling process is complete.


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"

chemical etching process
Click on the image for PDF

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. Photo Chemical 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.