Essentials of Photochemical Machining (Parts 1-4)

“Essentials of Photochemical Machining”

presented by: David Allen, BSc, PhD, DSc, FCIRP | Emeritus Professor of Microengineering, Cranfield University, UK

• What to Expect: Part 1
  • Front end for an electronics assembly etched from 0.010 in. thick AISI 316L stainless steel.
• What to Expect: Part 2
  • Photoresist Development Variables and Control
    • Break-point (dwell time in a conveyorized developer chamber)
    • Temperature
    • Chemistry
    • Dry film type and thickness
    • Spray pattern and pressure
    • Rinsing and drying
• What to Expect: Part 3
  • Monitoring FeCl3 Etchants: a need to be predictive rather than reactive
    • Temperature (should be constant)
    • Baumé (specific gravity)
    • Free-acid (HCl) content
    • Oxidation-reduction potential (ORP)
    • Dissolved metal content
    • Additives (if applicable)
• What to Expect: Part 4
  • Regeneration with sodium chlorate – Often referred to as the BEAC (Balanced Etchant Analysis
    Controller) process.