Reliability of Solder Balls Under Combined Impact of Thermal, Mechanical and Ele

Type of work : 10% literature and technological study, 70% to develop efficient computational models for predicting the mechanical reliability of RDLs and their design optimization, 20% to design and conduct experiments to calibrate and validate the computational models.Background : The reliability of solder joints in automotive electronics is critical due to the harsh operating environments that these components endure. Solder balls, which form the interconnections in Ball Grid Array (BGA) packages, are particularly susceptible to various aging mechanisms. These include thermal cycling, vibrations and electromigration and thermomigration, all of which can significantly impact the performance and lifespan of automotive chips.Recent advancements in numerical simulation techniques have enabled more precise modelling of these complex interactions. By leveraging these technologies, we can gain deeper insights into the failure mechanisms of solder joints and develop strategies to mitigate them.The existing models on solder integrity and reliability are either fully dedicated to thermal-mechanical stresses or fully dedicated to electromigration effects which result in voiding and microstructural changes of solder balls. Nevertheless, in realistic scenarios the two aging mechanisms act concurrently and degrade the integrity of solder balls synergistically.Problem Statement : Automotive electronics are subjected to extreme conditions that can lead to the premature failure of solder joints. The combined effects of thermal-mechanical stresses with electromigration and thermomigration, are not fully understood. This lack of understanding hampers the development of more reliable and durable electronic components.Objectives : The primary objectives of this research are :

• To develop numerical physics-based modelling frameworks that can capture electromigration and thermomigration induced aging in solder balls. To this end imec has a solid track record in physics-based electromigration modelling of interconnects which will be leveraged toward solder reliability.
• To couple the electromigration model with existing thermal-mechanical modeling frameworks
• To experimentally calibrate and validate the models
• To leverage the validated models towards reliability predictions for different package design parameters and operating conditionsJoint imec- KU Leuven PhD position. The student will be enrolled in the Department of Mechanical Engineering, KU Leuven and will be conducting research at imec in collaboration with the Department of Mechanical Engineering. refer to imec PhD program page for details :  https : / / www.imec-int.com / en / work-at-imec / job-opportunities / phd-at-imec