PCB Technical - How to judge whether Wuxi SMD processing is short-circuited

In Wuxi SMD processing, if the PCB circuit board is short-circuited, it may produce irreversible results. Many factors can cause the short-circuit. For example, the quality of the PCB board is not good enough or the operation is improper. When checking whether the PCB board is short-circuited, the simpler method is to observe with eyes. In addition, you can also use some test instruments to make more accurate judgments. Here are two ways to find the potential that causes the PCB board to short-circuit. Reason method.

1. Test with a digital multimeter

To test whether the circuit board is short-circuited, you need to check the resistance between different points in the circuit. If visual inspection does not reveal any clues about the location or cause of the short circuit, grab the multimeter and try to trace the physical location on the printed circuit board. The multimeter method has received different comments in most electronic forums, but tracking test points can help you find out where the problem lies.

You will need a very good multimeter with milliohm sensitivity. It is relatively simple if it has a buzzer function to alert you when it detects a short circuit. For example, if you are measuring resistance between adjacent traces or pads on a PCB, you should measure high resistance.

If the measurement should be very low between two conductors in a separate circuit, the two conductors may be bridged internally or externally. Please note that two adjacent traces or pads bridged by an inductor (such as in an impedance matching network or discrete filter circuit) will produce very low resistance readings because the inductor is just a coil conductor. However, if the two conductors on the board are far apart and the resistance you read is small, there will be a bridge somewhere on the board.

Wuxi SMD processing

2. Relative to the ground test

Of particular importance is the short circuit involving ground vias or ground planes. A multilayer PCB with an internal ground plane will include a return path through the components near the vias, which provides a convenient location for checking all other vias and pads on the surface layer of the circuit board. Place one probe on the ground connection and touch the other probe on the other conductors on the board.

The same ground connection will also exist elsewhere on the board, which means that if you touch each probe to two different ground vias, the reading will be small. Pay attention to the layout when doing this, because you don't want to mistake the short circuit for a common ground connection. All other ungrounded bare conductors should have a high resistance between the common ground connection and the conductor itself. If the value read is very low and there is no inductance between the conductor in question and ground, the component may be damaged or short-circuited.

Wuxi SMD processing is a relatively popular processing technology in the electronics industry, and has many advantages. If the PCB board develops a serious short circuit during processing, it will "waste all previous efforts", so it is more critical to determine whether it is normal. In addition to the above-mentioned two methods to find the potential causes of PCB short circuit, there are other methods. For example, you can use a multimeter to measure the resistance to check whether the component is short. In short, you can choose a suitable method for detection according to the actual situation.