PCB Technical - Discussion on drop test and knock test on PCB production line

Discussion on drop test and knock test on PCB production line

Generally speaking, in addition to the normal assembly and testing process, the electronic finished product assembly plant will more or less establish several test and inspection control checkpoints in its production line to ensure the quality of the products it produces. The most commonly seen There are the following two checkpoints, which are set at the intermediate station between the completion of product assembly and electrical testing.

Tapping test
The main purpose of percussion is to check whether the finished product has any poor assembly, such as scratching the empty, fake solder, tin balls, tin balls of electronic parts, and whether the mechanism and screws are assembled in place.
The percussion test rod is usually made by inserting a [bouncing ball] into a wooden rod. Hold the end of the wooden rod when striking, and use the elastic ball to strike the finished product. It is best to turn on the power when striking the product. For products with pictures, please pay attention to whether the pictures appear abnormally, because some electronic parts with poor soldering may only have open circuit or short circuit problems when they are tapped. Usually the tapping test will be placed at the first level of the electrical test, because we don’t know whether the product has a problem after tapping. If there is no electrical test check after the tapping, it is very likely that defective products will flow out. In the hands of customers. The position of the knock is very important, because different positions produce different effects. It should be knocked in the place where the product can produce resonance. The general test should be repeated three times; it is best to find the most vulnerable part of the product design. For percussion, it will not be effective if it is only in the hollow area. In addition, the size and weight of the bouncy ball will affect the effect of percussion, so be careful.

Drop test
The drop test here refers to the quality verification before the product is shipped, not the drop test of DQ (Design Quality). The drop test is based on the naked damage of the product. The purpose is the same as the above-mentioned knocking test. To check whether the finished product has any assembly defects, this test and knocking test can complement each other. The knocking test focuses on "resonance", which is repeated three times. ; Falling is only done once. The fallen table top is made of solid wood, with a layer of 3~5mm electrostatic table mat on it. When doing the drop test, it is a free fall, without plugging in or turning on the power. As with the knock test, an electrical test must be done after the drop test to ensure that the product functions well without appearance damage. The height of the drop is usually from 76.2mm (3 inch) to 300mm, which is generally distinguished by the weight of the product. The heavier the weight, the lower the height of the drop. The following table is only an approximation, for reference only, and everything is subject to the actual products of each company.

Personal experience, the operators on the production line are not afraid to drop the products, so the drop test will drop lower and lower. In fact, the operator should know that the purpose of the drop test is to pick out the problematic products instead of letting the defective products flow out. In the hands of the customer, if the product is returned in the future, it is better to Q it down in the production line first, and the product should be rewarded if it is thrown to death. In addition, when doing product research and development, many machines have to fall above 76cm to survive, and they still fall on the concrete floor with six sides and four (eight) corners, so you don’t have to be afraid that the product will be damaged if you fall. On the ground, it hurts the appearance.

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