Nine Common Testing Techniques Used by Shenzhen PCB Circuit Board Company

Nine Common Testing Techniques Used by Shenzhen PCB Circuit Board Company

PCB circuit board inspection is a very important process. To ensure the quality of PCB products, what key points should be paid attention to when inspecting PCB circuit boards

1. It is strictly prohibited to use grounded testing equipment to contact electronic devices that are powered on the motherboard without an isolation transformer to detect PCB boards. It is strictly prohibited to directly test TV, audio, and other equipment without a power isolation transformer using equipment with a grounded casing. Otherwise, it is very easy to cause power short circuits with equipment such as the motherboard's powered air conditioning and computer, affecting integrated circuits, and further expanding the fault. 2. When testing the circuit board, attention should be paid to the insulation performance of the electric soldering iron. It is not allowed to use soldering iron with electricity. It is necessary to confirm that the soldering iron is not charged, and it is best to ground the shell of the soldering iron. 3. Before testing, it is necessary to understand the working principle of integrated circuits and their related circuits, and be familiar with the functions, internal circuits, main electrical parameters, functions of each pin, as well as the normal voltage, waveform, and working principle of the circuit composed of peripheral components. 4. Do not cause short circuits between pins. When measuring voltage or testing waveform with an oscilloscope probe, it is best to measure on the peripheral printed circuit directly connected to the pins. Any momentary short circuit can easily damage the integrated circuit. 5. The internal resistance of the testing instrument should be large. When measuring the DC voltage of integrated circuit pins, a multimeter with an internal resistance greater than 20K Ω/V should be selected, otherwise there will be significant measurement errors in the pin voltage. 6. Attention should be paid to the heat dissipation of power integrated circuits. Power integrated circuits should have good heat dissipation and are not allowed to operate at high power without a heat sink. 7. The lead wire should be reasonable. If it is necessary to add peripheral components to replace the damaged parts inside the integrated circuit, small components should be selected, and the wiring should be reasonable to avoid unnecessary parasitic coupling. 8. To ensure the quality of welding, it is necessary to ensure that the solder is firmly soldered, and the accumulation of solder and air holes can easily cause false soldering; The integrated circuit that has been soldered should be carefully inspected to confirm that there is no solder adhesion before connecting to the power supply. 9. Do not easily determine the damage of integrated circuits. The vast majority of integrated circuits are directly coupled. Once the circuit is abnormal, it may cause multiple voltage changes, which may not necessarily be caused by integrated circuit damage, as some soft faults do not cause changes in DC voltage.