This test does not cause any damage to the product, so it depends on your mood when you test it. First of all, we need to know whether our purpose is to measure whether the width of the wire obtained through production is consistent with the original circuit design requirement on the customer's circuit pattern. Secondly, we need to know what kind of equipment we need for testing. These equipment include a scaled microscope (X50) that can capture 0.001'. The microscope can be placed perpendicular to the surface of the board. Of course, a projection magnifier is the best . The last step is the most important step, which is the entire process of testing. These processes have three main steps. 1) Prepare the test board: We can select the test area with the naked eye, and divide it into 0.500' long straight or curved areas, and then we number them. 2) Test evaluation: Check the width of each 0.500' curve area, and record the test results. Defects like some isolated gaps or protrusions are acceptable in principle, but they must be identified and measured. 3) Calculation: We take the width of the middle point between the highest point and the lowest point of each side as the average width of the parallel side wires. We should take the average of the three measurement results in each area to measure.