Photochemical Machining

Photochemical machining (PCM), also known as photochemical milling or photoetching, is a specialized manufacturing process within the realm of chemical machining. PCM is used for precisely etching and machining intricate patterns, shapes, and designs on the surface of thin metal sheets, often with high precision and fine detail.

Photochemical Machining Process

  1. Phototool Preparation: The process begins with the creation of a phototool, which is a precise photographic negative or positive of the desired part or pattern. This phototool is typically made from a photographic emulsion on a transparent or opaque substrate.
  2. Material Selection: A thin sheet of metal, often referred to as the workpiece or substrate, is selected based on the specific application and material requirements. Common metals used in PCM include aluminum, copper, stainless steel, and brass.
  3. Cleaning and Preparing the Workpiece: The metal sheet is meticulously cleaned to remove any contaminants or impurities from its surface. It is then coated with a light-sensitive photoresist material, which adheres to the metal.
  4. Exposure: The prepared metal sheet is placed in close contact with the phototool and exposed to UV light. The phototool’s pattern allows light to pass through in areas where material should be removed and blocks it in areas where material should be preserved. This exposure process chemically alters the photoresist on the metal, creating a latent image of the desired pattern.
  5. Developing: The exposed metal sheet is submerged in a chemical developer solution. The developer dissolves the unexposed photoresist, leaving behind a protective resist layer in the pattern of the phototool.
  6. Etching: The metal sheet, now coated with the developed resist pattern, is immersed in an etchant solution. The etchant chemically removes the unprotected metal, leaving only the desired pattern of material on the workpiece.
  7. Stripping and Finishing: After etching, the remaining photoresist is removed from the workpiece, and any necessary finishing processes, such as deburring or surface treatments, are applied to achieve the desired final product.

Photochemical machining offers several advantages, including high precision, repeatability, and the ability to create intricate, complex, and burr-free parts. It is commonly used in industries like electronics, aerospace, medical devices, and telecommunications for applications such as printed circuit boards, lead frames, gaskets, and fine mechanical components.