In order to ensure the quality of PCB production, the manufacturer has passed a variety of detection methods in the production process, each detection method will be aimed at different PCB defects. It can be divided into electrical test method and visual test method.
In electrical test, Wheatstone bridge is usually used to measure the impedance characteristics between test points to detect all the continuity (i.e. open circuit and short circuit). Visual test finds out the defects by visual inspection of the characteristics of electronic components and printed circuit. Electrical testing is more accurate in finding short circuit or open circuit defects. Visual testing can more easily detect the problem of incorrect gap between conductors. Visual testing is generally carried out in the early stage of the production process. Try to find defects and repair them to ensure the highest product qualification rate.
The common detection methods of PCB are as follows:
1. PCB manual visual inspection
Using magnifying glass or calibrated microscope and visual inspection by operators to determine the unqualified circuit board and determine when correction operation is needed, it is the most traditional detection method. Its main advantages are low pre cost and no test fixture, while its main disadvantages are subjective error, high long-term cost, discontinuous defect detection, data collection difficulties, etc. At present, due to the increase of PCB output and the reduction of wire spacing and component volume on PCB, this method becomes more and more infeasible.
