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Understand the failure analysis of PCBA in one article

119 Published by FASTPCBA 6月 18,2019

Understand the failure analysis of PCBA in one article

First,overview of modern electronic assembly connection craft

It is mainly expanded based on PCBA. Therefore, the research on the reliability of electronic assembly connection craft is mainly expanded with the phenomenon of failure occurring on PCBA.

The failure phenomena of PCBA can be divided into two categories that occur during the production process and occur during the service of the user. (1) Failure phenomena of PCBA (internal or surface) during the manufacturing process: such as bursting, delamination, surface excess, ion migration, and chemical corrosion (rust) etc. (2) Various failure modes and fault performance on PCBA during user service: such as virtual welding, solder joints brittle breaks, deterioration of microstructure and reliability in solder joints.

pcba

Second, the purpose of failure analysis

Fault analysis is the process of confirming the cause of the fault, collecting and analyzing the data, and summarizing the mechanisms that eliminate the failure that caused the failure of a particular device or system.

The main purpose of fault analysis is to;

Find out the cause of the failure;

Trace the adverse factors that exist in craft design, manufacturing procedure, and user service;

Propose corrective measures to prevent recurrence of the failure. Through the results accumulated by fault analysis, the craft design is continuously improved, the product manufacturing process is optimized, and the usability of the product is improved, thereby achieving the purpose of comprehensively improving product reliability.

Third, PCBA failure rate curve

1, PCBA product failure rate curve contains the following three levels, namely:

Component failure rate curve: Through the forced aging of components before leaving the factory, the failure rate of components during the service period of the user can be effectively reduced.

Component Supply Life Curve: It describes the lifetime of the component to the user and it has a significant impact on the reliability of the system.

PCBA assembly failure rate curve is mutually affected by SMD incoming life, SMD assembly life and solder joint life. At this point the life of the PCBA is essentially dependent on the solder joint life. Therefore, ensuring the quality of welding of each solder joint is a key link of ensuring high reliability of the system.

2, PCBA typical transient failure rate curve. The typical instantaneous failure rate of PCBA is referred to as the typical failure rate of PCBA. Instantaneous failure rate is the probability of failure of the unit time after the PCBA works to time t. The typical transient failure rate curve of PCBA consists of three areas: premature aging zone, product service zone and aging zone, as shown in the figure below.

Fourth, the level and principles and methods of PCBA failure analysis

1, The level of failure analysis in the production and application of electronic products, the control and analysis of PCBA and solder joint failure is basically the same as the reliability control and analysis methods of other systems.

2, The principle of failure analysis – the basis of mechanism reasoning

On-site information;

Retest (failure mode confirmation) result analysis;

specific craft of object and failure mechanism of structure;

a specific environment-related failure mechanism;

Relationship between failure mode and failure mechanism;

Long-term accumulation of knowledge and experience.

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