Basic procedure for failure analysis
The basic process of the Czech Republic PCB is to first determine the failure location and failure mode, ie failure location or fault location, based on the failure phenomenon, through information collection, functional testing, electrical performance testing, and simple visual inspection. For simple PCB or PCBA, the location of the failure is easy to determine. However, for a more complex BGA or MCM packaged device or substrate, the defect is not easily observed by the microscope, and it is difficult to determine at a time, and this time needs to be determined by other means.
The failure mechanism is then analyzed by using various physical and chemical methods to analyze the mechanism that causes PCB failure or defect generation, such as virtual welding, contamination, mechanical damage, moisture stress, dielectric corrosion, fatigue damage, CAF or ion migration, Stress overload and so on.
Then the failure cause analysis, that is, based on the failure mechanism and the process analysis, find the cause of the failure mechanism, and if necessary, carry out test verification. Generally, the test verification should be possible as possible, and the cause of the induced failure can be found through the test verification. This provides a targeted basis for the next step of improvement.
Finally, according to the test data, facts and conclusions obtained in the analysis process, the failure analysis report is compiled, and the facts of the report are clear, the logical reasoning is strict, the rules are strong, and it is forbidden to imagine.
In the process of analysis, Jeddah pcb noticed that the analytical methods should be used from simple to complex, from the outside to the inside, from the destruction of the sample to the basic principles of the use of damage. Only in this way can we avoid losing key information and avoid introducing new artificial failure mechanisms.
Just like a traffic accident, if one of the accidents destroys or flees the scene, it is difficult for the Gaoming police to make an accurate liability determination. At this time, the traffic regulations generally require that the party who flees the scene or the site at the scene bear full responsibility.
The same is true for the failure analysis of PCB or PCBA. If the soldering iron is used to repair the failed solder joints or the large scissors are used to strongly cut the PCB, then the analysis will not be possible, and the failed scene has been destroyed. Especially in the case of a small number of failed samples, once the environment of the failed site is destroyed or damaged, the real cause of failure cannot be obtained.