“3rd Level” Solder Joint Reliability Investigations for Transfer of Consumer Electronics in Automotive Use

Abstract

Developments directed towards autonomous driving require complex smart functionalities at reasonable cost, e.g., combined sensing and high volume data processing. Reliability remains a key issue in that process. However, in various cases dedicated automotive grade components are lacking. Therefore, thermo-mechanical reliability issues are one focus of the European project TRACE, which studies the issues for transfer of consumer electronics (CE) into automotive electronics (AE). Gaps between these use scenarios are figured out and measures to be taken are searched [1].Besides the well-known harsh environmental AE requirements, mounting induced effects on components loadings need to be considered. These mounting conditions superimpose stresses driven by the component-board induced CTE mismatch and are in particular critical for leadless components like QFNs, LGAs; WLPs, characteristic of CE use. For evaluation of this loading scenario, a combined measuring-simulation technique has been developed. It uses an optical multi-sensor metrology system for the thermo-mechanical deformation measurement of electronic components and systems for different size and resolution ranges. An application to critical components in an electronic control unit (ECU) is depicted.The combined experimental-numerical method is applied to test-setups, to figure out effects from board mounting on component reliability and characteristic limits due to mounting. Test-boards with systems in QFNs are analyzed. It is shown, that system effects can have major impact on components stress and solder fatigue life.