Analyzing, locating, and repairing circuits is the basic work of hardware engineers and there will always be all kinds of strange problems. We need to gradually locate and solve the problems one by one to reduce the failure rate, improve the production line yield, and improve the average Trouble-free time and reduce after-sales problems.
This section introduces several common analysis ideas, which are common in hardware circuits such as mobile phones, tablets, and computers.1.Poor soldering - short circuit.
The factory may cause partial tin connection during SMT, and the amount of tin connection is not much. Therefore, the system is normal when it is first used. As the temperature rises or the board vibrates, the tin connection begins to affect the circuit, which in turn makes the circuit work abnormally.
This is also a common soldering problem, many students have encountered, some ICs do not work properly, after soldering (that is, re-soldering) can be used normally, which is likely to be a false soldering.
(Source:Kemo Electronic GmbH)
3.Vibration leads to false solder.
PCB circuit boards will inevitably vibrate during use, such as motor vibration in mobile phones, propeller vibration in drones, or daily drops. These high-frequency vibrations are likely to cause components to fall off or aggravate the false solder.
4.Vibration causes chip damage.
This needs to be seen clearly under a digital microscope, and it can be seen that there are cracks on the surface of the chip;
Sometimes there is no abnormality on the surface, but the inside of the chip is damaged. The original chip manufacturer needs to perform root cause analysis. Therefore, engineers generally check the appearance and impedance of abnormal ICs. At the same time, the students in charge of the structure should analyze whether the chip is in a stress-sensitive area.
5.Chip burned out.
This also needs to be observed through a digital microscope. For a product with a very compact project schedule, both the chip manufacturer and the product need to analyze the problem synchronously, and exclude their own circuit and exclude the IC.
(Chip under AD407 pro digital microscope)
6.There is a problem with the chip itself.
Chips also have factory batches, and the production environment of different batches will be more or less different. It is possible that this batch of chips has problems in itself.
This is one of the most annoying reasons.....
Andonstar is specialized in the research, development and production of digital microscopes. Our digital microscopes are ideally suited for circuit board repair and are an essential tool for locating and repairing soldering faults in your circuit boards.