Reliability assessment of electronic assemblies under multiple interacting loading conditions

Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Juha Karppinen Name of the doctoral dissertation Reliability assessment of electronic assemblies under multiple interacting loading conditions Publisher School of Electrical Engineering Unit Department of Electronics Series Aalto University publication series DOCTORAL DISSERTATIONS 19/2013 Field of research Electronics integration and reliability Manuscript submitted 17 September 2012 Date of the defence 14 February 2013 Permission to publish granted (date) 14 December 2012 Language English Monograph Article dissertation (summary + original articles) Abstract This dissertation presents the results of multiple experimental and computational reliability assessment methods employed on electronic assemblies. It is demonstrated that the typical standardized test procedures often fail to capture the complex loading conditions of service environment and can lead to artificial results due to excessive damage acceleration. An alternative reliability assessment approach based on the use of combined loading tests derived from product service loading characterization is proposed as a solution to the problem. In this proposed approach special attention is paid to establishing a stronger correlation between the material-scientific reliability analyses and lifetime prediction methods.This dissertation presents the results of multiple experimental and computational reliability assessment methods employed on electronic assemblies. It is demonstrated that the typical standardized test procedures often fail to capture the complex loading conditions of service environment and can lead to artificial results due to excessive damage acceleration. An alternative reliability assessment approach based on the use of combined loading tests derived from product service loading characterization is proposed as a solution to the problem. In this proposed approach special attention is paid to establishing a stronger correlation between the material-scientific reliability analyses and lifetime prediction methods. Several methods on how to predict and characterize the reliability of component assemblies under different use cases and field environments are presented. Particular emphasis is placed on the reliability of board-level solder interconnections due to their complex and often unsatisfactory reliability behavior. It is shown that multiple microstructural mechanisms, such as dispersion strengthening, grain growth, strain rate hardening, fatigue and recrystallization, contribute together to the reliability performance of interconnections. The presented relationships between these mechanisms and the affecting loading conditions enable more accurate and comprehensive assessment of electronic product reliability.