Information digest：
The problems of blind hole and blocked hole mainly occur in the intensive etching mesh parts.
The phenomenon of hole blockage is one of the most common defects in the production of precision etched mesh, which directly affects the filtering performance, flow rate and yield of finished metal mesh parts. In mass production, many engineers and procurement staff often attribute blocked micropores to poor raw material quality, while ignoring multiple interconnected factors in the photochemical etching process. Understanding the root causes of hole blockage helps optimize the manufacturing process and reduce scrap rate for micro mesh used in new energy, medical devices and semiconductor industries.
Raw material and surface pre-treatment is the first link that easily triggers hole blockage. Before etching, metal sheets such as stainless steel, copper and nickel alloy need to be thoroughly degreased to remove oil stains, dust and oxide layers on the surface. If degreasing is incomplete, residual grease will adhere to the tiny holes during exposure and development. These contaminants cannot be washed away completely, forming solid residues inside micropores. In addition, uneven surface oxidation of the base material will lead to inconsistent photoresist adhesion. Partial photoresist peeling during subsequent processing produces debris that accumulates in small holes, resulting in partial or full hole blockage. The thinner the metal sheet and the smaller the aperture, the more sensitive the etched mesh product is to pre-treatment defects.
Photoresist coating, exposure and development processes are the core sources of etched mesh hole blockage. When applying photoresist, excessive coating thickness will leave residual photoresist at the bottom of micro holes after exposure. Insufficient exposure energy causes the photoresist to fail to undergo complete photochemical reaction. In the development stage, unreacted photoresist cannot be dissolved and washed off, and remains inside the designed micropores, forming permanent hole blockage. On the contrary, overexposure will lead to photoresist undercut, the pattern edge becomes blurred, and the broken photoresist fragments fall into the holes. Improper development pressure and insufficient flushing flow are also critical points. If the spray pressure is too low, the developer cannot wash away dissolved photoresist from tiny holes; excessive pressure may damage the photoresist layer and generate new debris, further inducing hole blockage on theetched mesh. Etching solution status and etching operation parameters have a significant impact on etched mesh hole clogging. During continuous etching production, metal ions continuously dissolve into the etching liquid. As metal ion concentration accumulates excessively, precipitation will occur inside the micropores and deposit solid sediment. Temperature fluctuation of etching bath, uneven liquid circulation and insufficient filtration of etching fluid will aggravate the precipitation of solid particles. These fine particles are easy to get trapped in micro holes and cause hole blockage. Moreover, improper etching time will also cause problems. Short etching time leads to incomplete penetration of the material, and the residual metal layer at the hole bottom looks like blocked holes. Excessively long etching time causes serious undercut, metal burrs and suspended fragments form inside the hole structure, blocking the effective channel of the etched mesh. Post-processing and environmental factors also cannot be overlooked. After etching, residual etching solution and metal particles remain in the holes. If the cleaning procedure is simple and the ultrasonic cleaning time or power is insufficient, residues cannot be removed thoroughly. When drying at high temperature, the residual solution will precipitate solid impurities inside the micropores and lead to hole blockage. Besides, workshop dust control is essential. Dust particles floating in the air may fall into the mesh holes after etching and be fixed during drying. Packaging and transportation without proper protection can also introduce foreign debris, resulting in secondary hole blockage of finished etched mesh.
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