From the perspective of PCBA circuit reliability misunderstandings, I believe that one of the first misunderstandings in the minds of many people who do not understand the actual situation is that product failure = product unreliability. Of course, this is a relatively one-sided perception, because PCBA circuit board products have problems, and sometimes it is not a problem of research and development. There have been cases where equipment for medium and above developed regions in China was exported to Colombia because it was used well in the country, but there were frequent failures. The cause of the failure was that the altitudes of the medium and above developed regions in mainland China were relatively low, so high altitude In areas, the airtightness of the equipment has been challenged, and the pressure difference between the inside and outside of the equipment has increased and the leakage rate has increased. The standard for evaluating the reliability of PCBA circuit board products is "the ability to complete the specified functions within the specified time and under the specified conditions." After all, when the project was established, it was aimed at the country and only considered low altitude, but we cannot deny the design of others because of this. In view of this situation, it is necessary to adapt measures to local conditions and analyze specific issues in detail.

Misunderstanding 2: The device can be used with confidence

Speaking of devices, general device damage is called "burn". As the name suggests, device damage is generally thermal failure. Here is one point to note. The device environment temperature ≠ the overall environment temperature, and the device environment is affected by heat dissipation by other devices in the chassis. Generally, the ambient temperature of the device is higher than the ambient temperature of the whole machine.

Misunderstanding three, derating is easy

Derating sounds quite simple and easy, but in actual operation, many factors must be considered. The following are summarized as follows: ①Different loads, different derating factors; ②Some parameters cannot be derated; ③Adjustable devices and settings The derating factor of the value device is different; ④ The derating factor of the device of the same function but different technology is different; ⑤ The derating factor is different when the wire of the same specification is used in multi-turn and single-turn applications; ⑥ The junction temperature derating cannot be omitted.

Misunderstanding 4: Strengthening testing can solve reliability problems

People's subconscious testing means = engineering calculation + specification review + simulation test + electronic simulation. Most people think that reliability problems can be solved as long as the tests are strengthened, but they do not realize that some problems cannot be detected at all through simulation tests. At the same time, the corresponding low temperature working time cannot be calculated through the results of the temperature enhancement test.