Photochemical etching (also called chemical milling or etching) is a precision metal fabrication process used to selectively remove material from a metal sheet. It primarily relies on chemical reactions from a photosensitive mask and UV light exposure. This method is often employed in industries requiring high-precision components, such as electronics, aerospace, and medical devices.

MET Manufacturing Group specializes in delivering high-quality sheet metal components through photochemical etching. We also have an extensive array of value-added services, which cover all aspects of a task’s requirements. This commitment to comprehensive support ensures that clients receive a comprehensive solution that addresses all aspects of their projects.

Step-by-Step Guide to Photochemical Etching

Here is a concise overview of the chemical etching process, demonstrating its precision and versatility in creating intricate metal components:

Preparation of Metal Substrate

In the initial step, the metal substrate undergoes a meticulous cleaning process to eliminate impurities or residues, typically left behind by the material mills or processing centers. This preparation is important as it ensures a clean and uniform surface, promoting optimal adhesion and performance of the photoresist layer. The cleanliness of the metal substrate also sets the foundation for the subsequent stages of the etching process.

Application of Photoresist

Following substrate preparation, a thin and even layer of photosensitive material called photoresist is applied to the metal surface. This coating serves as a protective mask for the following process stages. The uniform application of photoresist is critical to producing consistent results when forming intricate designs on the metal.

Exposure to UV Light

The coated metal sheet is subjected to UV light via a mask or phototool containing the desired pattern. This causes a chemical reaction in the exposed parts, altering their characteristics and resulting in a stencil that copies the specified design. The light exposure’s specificity and accuracy influence the etched pattern’s overall quality.

Development of Photoresist

During the development stage, the photoresist’s unexposed portions are carefully removed, revealing the pure metal surface beneath. The result is a finely produced and well-defined metal sheet pattern closely matching the intended design. These exposed portions are now set up for the photochemical etching process, which will leave the protected regions intact.

Chemical Etching

The metal sheet — with its patterned photoresist — is put through a conveyorized etching system that utilizes an oscillating spray chemical, Ferric Chloride, often called an etchant. This chemical solution selectively dissolves the exposed metal, as the photoresist acts as a barrier that prevents etching in the covered areas. The speed of the conveyor mixed with the strength or concentration of the acid bath are both factors to be considered by a skilled operator to achieve desired results.

Stripping of Photoresist

Typically, chemical strippers or other specifically designed methods are utilized to remove the remaining photoresist. These chemicals can effectively dissolve the photoresist material completely, leaving behind a flawlessly revealed metal surface. This meticulous removal ensures the etched pattern’s quality, clarity, and integrity.

Final Inspection and Finishing

The completed etched metal part undergoes a thorough inspection to ensure its quality and accuracy. Any necessary finishing processes — such as deburring or specific surface treatments — are applied to meet the exact requirements of the intended application. This final stage also guarantees that the etched metal part meets the specified standards for functionality and appearance. MET utilizes multiple Keyence vision and measurement systems to qualify and certify our finished products.

Industries Leveraging Photochemical Etching

Listed below are the industries that leverage chemical etching processes and their common applications:

Environmental and Safety Considerations in the Photochemical Etching Process

Environmental considerations are critical in the chemical etching process, where the use of chemicals and the potential for emissions require careful attention. The substances involved — including the photoresist and etchants — may pose environmental risks if not managed properly. Therefore, efforts are made to minimize the environmental impact by selecting eco-friendly substances and implementing proper waste disposal practices. MET Manufacturing is fully committed to the safety and efficient disposal of hazardous materials. MET works with the Indiana organization, The Heritage Group, to safely dispose of hazardous waste as a byproduct of our chemical etching.

Safety measures are also crucial in mitigating potential hazards associated with the handling of chemicals. Operators and workers must adhere to strict protocols, including the use of personal protective equipment (PPE) such as gloves, goggles, and protective clothing. In addition, training programs are implemented to educate personnel on the proper handling, storage, and disposal of chemicals.

Compliance with regulatory standards and guidelines ensures that the etching facility meets environmental and safety requirements. Regulatory agencies may impose restrictions on certain chemicals or set emission limits. These guidelines aim to prevent chemical spills, leaks, or improper disposal, safeguarding the immediate surroundings and larger ecosystems.

The following trends and technologies reflect the dynamic evolution of the chemical etching industry:

  • Advanced Materials and Alloys
    Engineers are increasingly tailoring metal compositions to meet specific application requirements. For example, advanced alloys allow for producing aerospace parts and components with optimal strength-to-weight ratios. This trend expands the capabilities of photochemical etching, making it a preferred choice for a broader range of industries seeking specialized material properties. Advanced etching alloys include nickel, invar, hastelloy, Kovar, HyMu and other shielding alloys.
  • Digital Photo Tools and Imaging Technologies
    High-resolution digital masks offer unparalleled precision and flexibility in designing intricate patterns. Digital tools also facilitate rapid prototyping and iteration, reducing the time and costs associated with traditional phototool production. This trend aligns with the broader industry shift toward digitalization and automation, which fosters efficiency and responsiveness in the etching process.
  • Green Chemistry Practices
    Green chemistry practices involve the development and implementation of eco-friendly materials and processes. This trend aligns with sustainability goals and regulatory requirements, appealing to more environmentally conscious industries. Moreover, the shift toward green chemistry practices positions chemical etching as a responsible and sustainable manufacturing method.
  • Nanotechnology Applications
    Photochemical etching is finding new applications in nanotechnology, enabling the fabrication of nanostructures with precise control over size and shape. This opens new frontiers in the creation of nanoscale devices and components. In fields such as electronics, sensors, and medical diagnostics, the ability to etch at the nanoscale allows for producing highly sensitive and efficient devices.

Choose MET Manufacturing Group for High-Quality Etching Solutions

At MET Manufacturing Group, we provide quality etching solutions, particularly catering to thin gauge and precision sheet metal applications! Our expertise lies in harnessing the precision and intricacy offered by chemical etching to meet the exacting standards of various industries. We also extend our capabilities to various value-added services, including forming, plating, heat treating, and kitting.

Contact us today or request a quote to get started with us!