Advantages of Photochemical Etching Over Other Methods
There are many reasons why many fabricators prefer photochemical etching in working with thin components and engraving tasks. Below are some of the advantages of photochemical etching:
Photochemical Etching Vs. Electrolytic Etching
Cost-Effective
On the industrial scale, where components are produced in high volumes, fabrication through photochemical etching is far more superior as compared to electrolytic etching. Its capability for multiple bulk outputs in one running will lessen production time, thus lessening operational costs.
Material Flexibility
As the name implies, electrolytic etching uses electrical discharges. Hence, only electrically conductive metals can be used as materials. This is not the case with photochemical etching. With this method, almost all metals can be processed. Thin metals that usually tend to cause problems due to their fragile state when manufactured are used in photochemical etching with ease.
Design Flexibility
Being able to use almost all metals, as mentioned above, the possibilities of complex designs that are usually limited by the type of material being used are endless. This limiting factor is out of the picture. The troubles of compromising are no longer an issue.
Quality Output
According to an article from VECO's website, electrolytic etching can result in micro burring, tempering, and structural changes since it uses high-temperature electrical current. In chemical etching, the process involves the workpiece being exposed only to a certain chemical, and no substantial force that can cause burring is induced.
Photochemical Etching Vs. Plasma Etching
Wider Range of Application
Unlike plasma etching that is suited for producing semiconductor devices since it mainly uses plasma ash to complete the process, photochemical etching is not limited to a certain industry. It is being utilized in the medical field, aeronautics, automotive industries, wafer fabrications, electronics industries, and even aesthetic industries.
Lower Cost of System
Plasma etching requires expensive equipment for optimal functionality. It requires a more sophisticated setup for its components, adding up to its complexity and expenses, unlike photochemical etching that usually uses equipment baths or spray systems of the desired chemical. The simplicity in its set up makes it a cheaper option.
Higher Etch Rate
As stated in a blog post from Science Direct under materials science topic, plasma etching utilizes the kinetic energy of particle beams such as ion beam, electron beam, or photon beam to attack the substrate. Dealing with materials at atomic levels tends to take a longer time since it relies solely on the high-energy particles knocking out the surface's substrate. However, in photochemical etching, the workpiece is either immersed or sprayed with a chemical that reacts with the substrate atom through diffusion speeding up the etching process.
Higher Selectivity
Plasma etching has the advantage of anisotropic etching, perpendicular direction; however, this also limits its selectivity. Modernization demands more complex designs for their perusal. Photochemical etching is anisotropic etching. Wherein it etches equally in all directions, can cater more ideally to these demands.
Better Surface Finish
An excerpt from the book entitled Advances in Chemical Mechanical Planarization states that plasma etching itself can induce damage on the surface of a material. This writing is supported in the research uploaded by Ravi Ramanathan with the topic of Plasma Etch Induced Surface Damage and its Impacts on GaAs Schottky Diodes. It was written here that dry etching could induce surface damages that will affect the physical and electrical properties of devices due to high energy ion bombardments and the presence of reactive ion species. These damages include surface roughness. For photochemical etching, the addition of chemical additives can favourably improve surface quality addressing the issue.
Photochemical Etching Vs. Thermal Etching
Tested Compatibility with Different Materials
Unlike thermal etching that has been studied most extensively only on silver, photochemical etching has explored many other metals to use as material and has succeeded in processing them. These metals include but are not limited to aluminium alloys, beryllium copper, copper alloys, steel, nickel, titanium alloys, silver, and many other metals commercially in use.
Better Quality
An experimental research headed by Garcia de Andres in Spain with the title Thermal Etching Method concluded that metals exposed to a very high austenitization temperature state the following facts. The grooves that reveal the austenite grain boundary can interfere with the grain boundary advancement, producing the spasmodic migration of the grain boundaries along the polished surface and the ghost traces' presence in the boundaries. Such is not the case with photochemical etching. The chemical reacts passively with the metal while not inducing a force that can bend or deform the material. This phenomenon allows it to remove parts without altering the metal's properties effectively.
You can see a similar article here https://www.iqsdirectory.com/articles/metal-etching/photochemical-etching.html
Both are written by John Hamlin