PCB production in-line drop test and knockdown test discussion

In general, In addition to the normal assembly and testing process, the electronic finished product assembly plant will establish more or less control checkpoints for testing and inspection to ensure the quality of the products it produces. The most common ones are the following two. The road level is set at the intermediate station between the completion of product assembly and electrical testing.

Tapping test

The main purpose of tapping is to check whether the finished product has any poor assembly, including scratching Empty, false soldering, solder balls, solder balls of electronic parts, and whether the mechanism and screws are assembled in place, etc.
The percussion test stick is usually made by inserting a [bounce ball] into a wooden stick. When tapping, hold one end of the wooden stick, and use the elastic ball to tap the finished product. It is good to turn on the power. Products with a screen should pay attention to whether the screen is abnormal, because some electronic parts with poor welding may only have an open circuit or a short circuit when they are tapped. Usually the knock test will be placed in the first level of the electrical test, because we do not know whether the problem of the product has been knocked out after the knock. If there is no electrical test check after the knock, it is very likely that defective products will flow out into the hands of customers. The position of the tapping is very important, because different positions produce different effects. It is necessary to tap on the solid part of the product where resonance can occur. Generally, the test requires three consecutive taps; it is best to find the weakest part of the product design. For knocking, if you only knock on the hollow place, it will have no effect. In addition, the size and weight of the bouncy ball will affect the effect of the percussion, so you should pay attention.

Drop test

The drop test here refers to the quality verification before the product is shipped, not the DQ (Design Quality) drop test. The drop test is based on the bare damage of the product. The purpose is the same as the above-mentioned knock test. It is to check whether the finished product has any poor assembly. This test and the knock test can complement each other. The knock test focuses on "resonance" and taps three times in a row. ; if it falls, it will only be done once. The fallen desktop is made of solid wood with a layer of 3~5mm electrostatic table mat on it. For the drop test, it is a free fall, not plugged in or turned on. Like the knock test, an electrical test must be done after the drop test to ensure that the product functions well and has no cosmetic damage. The drop height 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 drop height. The following table is only an outline and is for reference only. Everything is subject to the actual products of each company.

Personal experience, the operators in the production line are not afraid to drop the product, so the drop test will be lower and lower, in fact, the operator should know that, The purpose of the drop test is to pick out problematic products. Instead of letting the defective products flow out to the customer and be returned in the future, it is better to take them down on the production line first. If the product is dropped, you should be rewarded. . In addition, when R&D is doing product research and development, many machines have to be dropped to more than 76cm and not die, and they are also dropped on the cement floor with six sides and four (eight) corners, so there is no need to be afraid that the product will be broken when falling. It was accidentally dropped to the ground, hurting the appearance.