Photo Chemical Etching (PCE), also widely known as photochemical machining (PCM), is a precision subtractive manufacturing technology that combines photolithography imaging and controlled chemical corrosion. As a low-stress, non-contact and high-flexibility metal processing method, it has gradually become an indispensable core process for manufacturing ultra-thin, micro and complex precision metal components. Different from traditional mechanical processing such as stamping, CNC milling and laser cutting, photo chemical etching removes metal materials through atomic-level chemical redox reactions without mechanical extrusion, impact or thermal deformation. This unique processing mechanism enables PCE technology to solve common industrial problems including burrs, residual stress, material warping and micro-cracks, which are difficult to avoid in conventional machining. At present, the photo chemical etching process is widely applied in stainless steel, copper, aluminum, nickel alloy and other precision metal parts, covering optical components, automotive systems, electronic equipment, medical devices and new energy industries, becoming a key supporting technology for modern high-precision intelligent manufacturing.

The core working principle of photo chemical etching can be summarized into three core links: pattern imaging shielding, selective chemical corrosion and precise material removal. The whole process relies on photosensitive photoresist materials to form a protective mask on the metal surface. After UV exposure and development, the preset component pattern is accurately transferred to the substrate surface. The photoresist-protected area is isolated from the etching solution and retains the original metal structure, while the exposed unprotected area undergoes uniform chemical dissolution to achieve targeted material removal and component forming. Compared with physical processing, PCE controls the etching range and depth through chemical formula and process parameters rather than mechanical force, so the dimensional accuracy and edge uniformity of products are not affected by metal hardness, toughness and thickness. This fundamental advantage makes it especially suitable for ultra-thin metal sheets below 2mm and micro-components with complex hollow, mesh and special-shaped structures.

The complete industrial workflow of photo chemical etching follows standardized and rigorous procedures, mainly including substrate pretreatment, photoresist coating, UV exposure, pattern development, chemical etching and post-treatment finishing. Each procedure directly determines the final precision, surface quality and batch consistency of etched parts. Substrate pretreatment is the primary foundation of high-quality etching. Metal sheets are prone to surface oil stains, oxide layers and dust contamination during production and storage. These impurities will cause poor photoresist adhesion, pattern falling off and uneven etching. Standard pretreatment includes alkaline degreasing, acid activation and multi-stage pure water cleaning, which thoroughly removes surface contaminants and improves the hydrophilicity and bonding performance of the metal surface, ensuring uniform photoresist coverage and stable subsequent reaction.

Photoresist coating and UV exposure are the core imaging steps of the entire process. Industrial production adopts two mainstream coating methods: dry film lamination and wet photoresist coating. Dry film photoresist features uniform thickness, stable bonding and high efficiency, suitable for mass production of conventional metal parts. Wet photoresist is more adaptable to ultra-thin sheets and ultra-fine micro-nano patterns, which can fit tiny surface gaps and improve pattern resolution. After coating and drying, the metal substrate is aligned with a customized precision photomask and exposed under ultraviolet light. The photoresist in the light-transmitting area undergoes polymerization curing to form a dense and corrosion-resistant protective layer, while the photoresist in the light-shielding area remains unreacted and soluble. This step accurately fixes the component contour and realizes one-to-one transfer of design patterns to the metal surface.

The development process is responsible for revealing the target etching pattern. After UV exposure, the substrate is cleaned with professional developing solution to completely dissolve and wash away the unexposed photoresist. The exposed metal area is the part that needs chemical etching, while the cured photoresist area forms an effective barrier. The edge sharpness after development directly affects the dimensional tolerance of finished products. High-precision development treatment can avoid pattern blurring and edge serration, laying a foundation for micron-level precision processing. After inspection and correction, the substrate enters the core chemical etching stage.

Chemical etching is the key forming procedure of PCE technology. Industrial production mainly uses ferric chloride composite etching solution, with auxiliary additives to adjust reaction rate, inhibit lateral erosion and optimize surface flatness. According to different metal materials such as stainless steel, copper and aluminum, the solution formula, temperature and spraying parameters are dynamically adjusted to adapt to different metal chemical activity characteristics. The spraying etching method ensures uniform contact between the etching solution and the metal surface, realizing synchronous corrosion of the front and back of the workpiece. The main controllable parameters include etching temperature, solution concentration, spraying pressure and processing time. Reasonable parameter matching can effectively control the etching depth and side etching amount, stably controlling the dimensional tolerance of precision parts within ±0.01mm. The whole etching process belongs to cold chemical reaction, with no high-temperature thermal effect, ensuring no structural damage to the metal material.

Post-treatment is the final guarantee for product surface quality and service performance. After etching, the residual cured photoresist on the surface is removed by alkali stripping solution, followed by neutralization cleaning to eliminate residual acidic etchant and prevent secondary metal corrosion. For high-end parts used in optics, medical and precision electronics industries, fine polishing and surface passivation treatment can be added to remove tiny etching traces and further improve surface flatness and corrosion resistance. Finally, multi-stage pure water cleaning and constant-temperature drying are carried out to ensure no chemical residue on the workpiece surface, meeting industrial assembly and application standards.

Compared with traditional metal processing technologies, photo chemical etching has prominent and irreplaceable technical advantages. Firstly, the whole process produces no mechanical stress, no extrusion deformation and no fatigue damage, which perfectly solves the deformation problem of ultra-thin metal sheets that cannot be avoided by stamping and CNC processing. Secondly, PCE processing has completely burr-free and crack-free edges, with uniform and smooth surface, fully meeting the ultra-high precision requirements of optical and electronic components. In addition, the process has extremely high production flexibility. It only needs to replace the photomask to realize rapid production of complex patterns without expensive mold opening, greatly reducing the cost of small-batch and customized parts. Moreover, PCE has excellent batch consistency, stable product tolerance and high yield, which is suitable for large-scale standardized industrial production.

Benefiting from its unique processing characteristics, photo chemical etching technology has achieved wide penetration in multiple high-end manufacturing fields. In the optical industry, it is used to produce precision diaphragms, grating sheets, optical mask frames and filter fixing parts, with smooth etching surface that does not interfere with optical transmission and refraction. In the automotive industry, PCE manufactures sensor gaskets, fuel system filter sheets and thermal management precision parts, adapting to complex and harsh vehicle working conditions. In the electronic industry, it produces precision filter meshes, conductive shims and electromagnetic shielding components, providing high-stability basic parts for precision electronic equipment. In addition, it is also widely used in medical device accessories, new energy battery components and aerospace precision parts, showing strong industrial applicability and market value.

In summary, photo chemical etching is a mature, efficient and environmentally friendly precision manufacturing technology. Through standardized imaging, selective corrosion and fine post-treatment processes, it realizes stress-free, burr-free and high-precision forming of various complex metal precision components. Breaking through the technical bottlenecks of traditional mechanical processing, PCE has become the preferred process for ultra-thin and micro precision metal parts. With the continuous upgrading of high-end manufacturing requirements in optics, automobiles, electronics and new energy industries, photo chemical etching technology will further develop towards intelligence, high precision and green production, continuously expanding its application scope in the field of modern precision manufacturing.