With the high density of electronic products and lead-free electronic manufacturing, the technical level and quality requirements of PCB and PCBA products are also facing severe challenges. In the process of PCB design, production, processing and assembly, stricter process and raw material control are needed. Due to the technique and technology is still in the transition period at present, the understanding of the customer for PCB and assembly process has bigger difference, so similar to the leakage, and open circuit (line, hole), welding, such as blasting plate layered failure often occurs, often cause the quality responsibility of the dispute between suppliers and users, this led to a serious economic loss. Through the failure analysis of PCB and PCBA failure phenomenon, through a series of analysis and verification, find out the cause of failure, explore the failure mechanism, to improve product quality, improve production process, arbitration failure accident is of great significance.

PCB failure analysis can:

1. Help manufacturers to understand product quality status, analyze and evaluate process status, optimize and improve product research and development programs and production processes;

2. Identify the root cause of failure in electronic assembly, provide effective electronic assembly site process improvement plan, and reduce production cost;

3. Improve the qualified rate and reliability of products, reduce maintenance costs, and enhance the competitiveness of the enterprise brand;

4. Clarify the responsible party causing the product failure to provide a basis for judicial arbitration.

What is PCB failure analysis

PCB failure analysis of the basic procedures

To obtain the exact cause or mechanism of PCB failure or defect, basic principles and analysis procedures must be followed, otherwise valuable failure information may be missed, resulting in failure of analysis or may be wrong conclusions. The general basic process is that, based on the failure phenomenon, the failure location and failure mode must be determined through information collection, functional testing, electrical performance testing and simple appearance inspection, that is, failure location or fault location.

For simple PCB or PCBA, the location of failure is easy to determine, but for more complex BGA or MCM packaged devices or substrates, the defect is not easy to observe through a microscope, not easy to determine at that time, this time need to use other means to determine.

Then it is necessary to analyze the failure mechanism, that is, use various physical and chemical means to analyze the mechanism leading to PCB failure or defect, such as virtual welding, pollution, mechanical damage, wet stress, medium corrosion, fatigue damage, CAF or ion migration, stress overload, etc.

Another is failure cause analysis, that is, based on failure mechanism and process analysis, to find the cause of failure mechanism, if necessary, test verification, generally as far as possible test verification, through test verification can find the exact cause of induced failure.

This provides a targeted basis for the next improvement. Finally, the failure analysis report is prepared according to the test data, facts and conclusions obtained in the analysis process. The facts of the report are required to be clear, logical reasoning is rigorous, and the report is well organized.

In the process of analysis, attention should be paid to the use of analysis methods from simple to complex, from outside to inside, never destroy the sample and then to the basic principle of using destruction. Only in this way can we avoid the loss of critical information and the introduction of new artificial failure mechanisms.

Just like a traffic accident, if the one party of the accident destroyed or fled the scene, it is difficult for the police in Gaomin to make accurate responsibility identification, then the traffic laws and regulations generally require the one who fled the scene or destroyed the scene to assume full responsibility.

The failure analysis of PCB or PCBA is the same. If the failed solder joints are repaired with electric soldering iron or the PCB is strongly cut with large scissors, then the re-analysis will be impossible to start. The site of failure has been destroyed. Especially in the case of a small number of failed samples, once the environment of the failure site is destroyed or damaged, the real cause of failure cannot be obtained.