How the Metal Photo Etching Process Works

Photo etching takes advantage of techniques developed in the printing industry. We take a single image of your part and digitally array the image as many times as possible to cover a sheet of material that is typically about 12” x 18.” For some of the smallest parts we have produced, such as ophthalmic sutures, we can fit literally thousands of parts on a single sheet. Etching allows us to produce many parts at one time, rather than one-at-a-time as with stamping or laser cutting. And, we can also produce parts up to 24" x 60.”

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The Photo Etching Process: Step-by-Step

• 1

  You send us data files (dxf, dwg, etc.) so that we can generate the phototools. We can work from paper drawings or sketches, but having you create the file is much more economical for you.

• 2

  We produce a tooling file with compensating factors specific to the etch process, and array the images and then generate a mirrored image to create the front and back tools.

• 3

  The tooling file is output to a high resolution photo-plotter and matching front and back photo tools are generated. The tools are then aligned, registered and inspected thoroughly.

• 4

  The metal specified on the order, is pulled from our stockroom and cut into sheets for processing. For some very thin gauge materials, we may clean and coat the material coil-to-coil.

• 5

  The processing sheets are put through an automated cleaning line that has several chemical cleaning chambers. All of our cleaning solutions are aqueous and environmentally friendly. The cleaned sheets are rinsed in filtered de-ionized water. The cleaned materials are thoroughly inspected before the next step.

• 6

  Laminating and printing are done in a controlled clean room. First, the cleaned process sheets are vacuumed to remove any dust particles. The next step is laminating both sides of the material with acid-resistant photopolymer.

• 7

  Printing (also referred to as “imaging”) is done in a vacuum frame printer. It is here that the photo tool meets up with the coated metal sheet. The photo tool is inserted into the vacuum drawer on registration pins. Since the image from the tool is printed, on both the top and bottom of the coated metal sheet, it is extremely important that both pieces of the photo tool are aligned properly. Once the tool is registered and secured in the frame, the coated metal sheet is placed between the two pieces of film. The top of the vacuum frame drawer is brought down and locked into place. Once locked, a vacuum is created and an intimate contact between film and resist-coated metal is established. After the vacuum cycle is complete, the drawer travels on rollers into the print cabinet, where shutters open, and 5kw-8kw lamps expose the coated sheet. All clear areas of the photo tool allow light through to the resist which polymerizes or “crosslinks” in the exposed areas. The black areas of the tool block light and prevent exposure.

• 8

  The exposed sheets are sent to developing where they are loaded onto a transport conveyor. The sheets then travel through a spray chamber where a tightly controlled (temperature & pH) aqueous developing solution selectively dissolves only the un-polymerized areas of the exposed sheet. After developing, the sheets are rinsed and dried. The sheets of metal now have the exact part images replicated in acid-resistant film on both the top and bottom surface. All areas of the sheets from which the resist was removed have exposed metal that is ready for Photo etching.

• 9

  Etching machines are multi-chambered and use driven-wheel conveyors to transport the processing sheets. Spray tubes channel heated reagent (acid) to spray nozzles that disperse the fluid evenly over the top and bottom surface of the metal sheets. As the sheets travel through the etcher, the exposed metal areas start to dissolve and at the end of the process, all unwanted metal is gone and only the finished part, still protected by the photo resist, remains intact. The parts travel through rinse chambers to remove all traces of etching solution. The parts are inspected before the next step.

• 10

  The etched sheets are processed through a stripping machine that removes the resist using a heated solution of caustic and water. Once stripped of resist, the parts are rinsed multiple times and dried in a turbo dryer. The clean, dry parts are delivered to our Quality Inspection department.

• 11

  The parts are thoroughly inspected in accordance with our Quality Management System and to the customer’s specifications. Conforming parts are packaged and shipped.