There are two methods for removing epoxy stains: wet method and dry method, and I will explain them one by one below: The first wet method: IH2SO4-HF treatment method: First, use concentrated sulfuric acid for 30 seconds to 1 minute. The epoxy group reacts with SO4-2 to produce water-soluble yellow-brown epoxy sulfonate, thereby removing the epoxy smear layer on the pore wall. Then use HF aqueous solution to etch the exposed glass fiber to obtain a smooth hole wall surface; in order to facilitate electroless copper plating. II Potassium permanganate oxidation method: Firstly, the multilayer board is immersed in an organic solution to swell the epoxy resin, and then the swollen epoxy resin is removed with the potassium permanganate oxidation solution heated to 500C. However, when washing with water Permanganate will decompose to form manganese dioxide and deposit on the board surface, causing secondary pollution. For this reason, reduction treatment is required after potassium permanganate treatment, and the overall process is more complicated. The treatment process for removing epoxy drill dirt with concentrated sulfuric acid is simple and reliable. To remove the glass fiber, one is to directly use concentrated hydrofluoric acid for treatment. Another method is to use a mixture of hydrochloric acid and ammonium bifluoride. HCL100m1/1 NH4HF2200g/1 Treatment time 3-4 minutes After HF etching the glass fiber, a white calcium fluoride CaF2 precipitate will be produced on the surface of the hole wall. To this end, it is necessary to immerse in 5% HCL for 3-5 minutes to make CaF2 react with HCL to form water-soluble CaF2, so as to remove the CaF2 deposits on the pore wall. The second type of dry treatment: This method uses plasma etching to remove epoxy contamination in a vacuum cylinder. Due to the low production efficiency of this method, it is only used under special circumstances, such as the production of polyimide and epoxy glass composites. For the multi-layer board, plasma is used to remove the resin contamination on the wall of the drilled hole.