PCM Process

Product Spotlight

Heat Exchanger Visit Tecan Limited Website PCM Process Heat Exchanger A leading manufacturer of customized micro precision parts, Tecan uses photo chemical etching to produce complex contours and designs precise to ±25µm and at a low tooling cost. The process greatly reduces limitations on channels, ridgetops, headers, collectors and port features. Fotofab Custom Parts Visit Fotofab, LLC Website PCM Process Fotofab Custom Parts Fotofab custom parts and PCM go hand in hand. Complex parts are produced with the strictest of tolerances and configurations at higher volumes, faster rates, and affordable costs. Fotofab works with material thicknesses from .0001” to .125” (.0025mm to 3.175mm), depending on the features required. Medical Saw Blades Visit Ätztechnik Herz GmbH & Co.KG Website PCM Process Medical Saw Blades We manufacture saw blades for medical technology from suitable stainless and medically harmless steels. Surface structures and contours can be completely etched on thin saws. Thicker ones are etched and later cut out with a laser.

What is Photo Chemical Machining?

The PCM Process by Professor David Allen, Cranfield University,UK. D.Allen@cranfield.ac.uk.

Terminology and products

Photo Chemical Machining (PCM) is also known as Photo Etching , Photo Chemical Milling, Photofabrication and Chemical Blanking. It plays a valuable role world-wide in the production of precision parts and decorative items, mainly sheets and foils.

Such products include:

  • Color television shadow masks
  • Integrated circuit lead frames
  • Surface mount paste screens
  • Heat ladders, plates and sinks
  • Optical attenuators, choppers and encoder disks
  • Grills, grids, sieves and meshes
  • Washers, shims and gaskets
  • Jewelry
  • Decorative ornaments
  • Signs, plaques and nameplates

The PCM process:

artwork generation and phototool production

Various methods exist for the production of phototools. The most commonly-used method is to produce a phototool of the correct size by using a laser photoplotter to selectively expose a photographic film according to computer-aided design data. Once this master image has been made it may be ‘stepped and repeated’ and contact printed to form a multiple image, registered, double sided phototool for use in production.

Metal preparation

Before coating the metal with photoresist, the metal is thoroughly cleaned to remove all dirt, rust, greases and oils so that good adhesion to the photoresist is obtained.

Photoresist coating

Photoresists are UV light-sensitive polymers that may be applied to the metal as a liquid by dip coating, flowing, roller-coating or electrophoresis. Dry film photoresists are applied by hot roller lamination.

Photoresist processing

The coating of the metal sheet with photoresist sensitises it. When this sensitised metal is put into the double-sided phototool and is exposed to UV light on both sides, an image is formed in the photoresist. This is then developed in a liquid formulation to form an adherent, durable image on both sides of the metal.

Etching

Virtually all materials can be etched, although some are etched more readily than others. The vast majority of PCM companies etch a very wide range of metals employing a relatively innocuous etchant, an aqueous solution of ferric chloride. It is important to ensure that the by products of the etching process are soluble in the etchant solution so that etching can proceed quickly. To maintain a constant etch rate, lower environmental impact and improve economics, some companies regenerate their ferric chloride etchant in-house.

Stripping and inspection

The final process of PCM is to strip off the resist, ensure that the metal is clean and that the dimensional specifications requested have been satisfied.

For more information, contact our Executive Director, Catherine Flaherty by phone: (508) 385-0085 or email: cflaherty@pcmi.org.