Debris or carbon particles if we use hydrocarbon oil as dielectric will always be there inside a micro hole after drilling it using micro electro discharge machining process. I would like to know the best way to remove these particles from the micro entity. Would it be dependent on the material on which the micro holes are generated?
What did you try so far? Here are some options, but it totally depends on your material if they are viable. Probably you have a combination of organic soot and of particles of your material.
- Ultrasonication in an organic solvent or in water with a detergent (dish soap, for example). A mixture of 100 parts water, 10 parts isopropanol and 1 part dish soap is very effective against soot and particles. You may vary the isopropanol content of the mixture, I'm not sure what is ideal.
- Annealing in air at maybe 400 to 500 °C or higher to burn carbon and hydrocarbons
- Prolonged oxygen plasma treatment to oxidize carbon and hydrocarbons
- Treatment with piranha acid (one part 30% hydrogen peroxide with three parts concentrated sulfuric acid); Be careful, it is called piranha because it devours many organic materials, including your flesh! Piranha can react violently if it comes in contact with excess organic material, so the sample has to be cleaned by ultrasonication first. Please talk to an experienced chemist before trying it if you are not familiar with this chemical.
Probably a combination would work best: First two steps of ultrasonication, perhaps first water with isopropanol and detergent, then acetone. This removes loose particles and soft organic residues. Aftwerwards annealing, plasma treatment or piranha. This removes resistant carbon or soot deposits. Finally -- in severe cases -- again ultrasonication in water with isopropanol and detergent, afterwards in acetone to remove particles that were loosened by oxidizing the firmly attached organic or carbon films in the previous step. Final rinse with isopropanol or ethanol, then blow dry with clean nitrogen.
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