7 Tips for PCB Testing
In this article, 7 tips for PCB testing are shared as follows:
1.Pay attention to the insulation properties of electric iron
Using a live soldering iron is not allowed. Make sure that the soldering iron is not charged. It is advisable to ground the soldering iron. Great attention should be put to the MOS circuit. It can be safer to use a low voltage circuit of 6 to 8 volts.
2.Understand the working principle of integrated circuits and related circuits
Before inspecting and repairing the integrated circuit, be familiar with the function of the integrated circuit, the internal circuit, the main electrical parameters, the function of each pin and the normal voltage of the pin, the waveform and the working principle of the peripheral components. If you have the above conditions, then analysis and inspection will be much easier.
3.Do not cause short circuit between pins
When measuring voltage or testing the waveform with an oscilloscope probe, the pen or probe must not be shorted between pins of the IC due to slippage. It is best to make measurements on a peripheral printed circuit that is in direct contact with the pin. Any short circuit can easily damage the integrated circuit, more careful in the test of flat integrated CMOS integrated circuits.
4.Large resistance of test instrument
When measuring the DC voltage of integrated circuit pins, use a multimeter whose head resistance is more than 20KΩ/V, otherwise some of the pin voltage will have greater measurement error.
5.Pay attention to the heat dissipation of the power integrated circuit
Power integrated circuits should have a well heat dissipation function. It is not allowed to work in high-power state but without the radiator.
6.Leads should be reasonable
If you need to use peripheral components to replace damaged parts in an integrated circuit, you should use small components, and the wiring should be reasonable to avoid unnecessary parasitic coupling. Particularly, the ground end between the audio amplifier integrated circuit and preamplifier circuit should be well handled.
7.Ensure the soldering quality
Soldering time is generally not more than 3 seconds, the power of the soldering iron heat is 25W or so. Integrated circuits which is well soldered should be carefully examined, it is best to use ohmmeter to measure if there is any short circuit between pins. Make sure there is no solder adhesion phenomenon, and then connect to the power supply.