Reliability Calculation of Printed Circuit Boards and Assemblies un-der Reference, Test and Operating Conditions

An essential reliability criterion of an electronic product is its lifetime. Reliability cannot be tested in the product; reliability-critical features must already be identified and evaluated during assembly development. An assessment of product quality, in terms of manufacturing quality and product reliability is imperative. Already during the product testing reliability-defining characteristics are determined. Quality and reliability are closely linked basic requirements. In addition to industry standard guidelines and applicable standards, knowledge of basic reliability statistics is advisable. For the test and reliability engineer, the mechanism, dynamics and effective range (e.g. temperature, mechanical load, humidity) of degradation during extended life tests are important. This text will explain the appearance and effect of degradation mechanisms on selected examples. Crack growth in solder joints by thermomechanical degradation and dendrite growth by electrochemical migration is considered using the example of a surface mounted component under test. In addition to the mechanisms, the basics of reliability statistics regarding data evaluation, reliability test planning and interpretation should be presented compactly. In addition, the text will provide an insight into the purpose and application of industry guidelines.