Evaluation of the cleanliness of electronic products in dust-free cloth applications
Cleanliness refers to the degree to which the workpiece is clean during use. It can be expressed by the weight of the residual contaminants on the workpiece. It can also be expressed by the particle size and quantity of residual contaminants on the workpiece. It can also be expressed by residual metal atoms, ions and ionic contamination, or by using residual organic matter or organic carbon. The content is expressed. For mechanical parts that do relative motion, the problem that has the greatest impact on service life and reliability is particle contamination, and the size and number of particles, especially when the particle size is just the same as the fit of the mechanical motion pair. The impact and harm are greatest. Because too large particles do not enter the gap, too small particles can swim in the gap. Therefore, the early cleanliness was later evaluated by the gravimetric method and changed to the particle size method. In the International Standard (ISO), the cleanliness is also the particle size method. Among electronic products, the problem that has the greatest impact on reliability is residual ion pollution, which causes electrical leakage, electromigration, short circuit, electrochemical corrosion, changes in electrical properties, and changes in insulation resistance. Therefore, the degree of ionic contamination is commonly used to evaluate the cleanliness of electronic products.