Students: Microstructure and mechanics of aluminum wire bonds

The Fraunhofer Institute for Electronic Nanosystems ENAS specializes in the development of smart systems — so-called intelligent systems for a wide range of applications. These systems combine electronic components, micro- and nanosensors, and actuators with communication interfaces. Fraunhofer ENAS develops individual components, the technologies for their manufacture, as well as system concepts and system integration technologies, and translates them into practical applications. Fraunhofer ENAS supports customer projects from the initial idea through design, technology development, or implementation using existing technologies, all the way to a tested prototype.

The department Micro Materials Center (MMC) focuses on the reliability of electronic components. The goal of this application-oriented research is to improve the reliability of electronic components through appropriate experimental investigations and the use of numerical models, and subsequently to predict their remaining service life.

Are you interested in the relationship between microstructure and mechanical properties and would like to deepen your knowledge through a practice-oriented research topic? If so, we are looking for you to join us as a student research assistant as soon as possible. You will then complete your master’s thesis with us on the topic "Correlation of microstructure to mechanical properties of aluminum wire bonds for power electronic applications to determine homogenized mechanical properties".

Be part of change

Power electronic assemblies are exposed to high electrical and associated thermo-mechanical stresses during operation. Process- and aging-dependent material data are required to evaluate their lifetime. In aluminum wire bonds, these material properties vary within the bond zone and change during use. To determine suitable material data, a fundamental understanding of the relationship between microstructure (e.g., grain size and grain orientation) and mechanical properties (e.g., Youngs modulus and hardness) as well as their change under load is necessary.

In this master's thesis, initial and damaged wire bond connections, evaluated in three different zones (bond wire, bond foot, bond contact), will be used to establish a spatially resolved correlation between the microstructure of the wire bond connection (orientation, grain size) and the local mechanical properties (hardness and Young's modulus). To this end, EBSD analyses of wire cross-sections will be performed and the corresponding data evaluated in order to specifically investigate the orientations and grain sizes in the different zones. In addition, the results of the EBSD analyses will be correlated with measurements by nanoindentation. Hardness and Young's modulus values are to be determined in the different zones, for which suitable measurement and evaluation parameters must be selected.

Following the experimental part of the work, the established correlation between grain orientation and Young's modulus or grain size and hardness will be used to homogenize the mechanical properties within the different zones. To this end, analytical methods available in the literature will first be used. Subsequently, simulation-based homogenization methods will be applied and the various homogenization methods will be compared with each other.

Accompanying the work, suitable literature searches will be carried out in the scientific literature. The written report should be designed in such a way that it serves as an efficient basis for further work. Approaches, models, and results must be presented in a comprehensible manner, discussed critically, and checked for physical plausibility. Any software or scripts developed as part of the work must be comprehensively documented and submitted as part of the work.

The following steps are essential to achieve the objective:

• Comprehensive literature review
• Determination of grain orientation and grain size using EBSD measurements
• Determination of mechanical properties using nanoindentation
• Evaluation of the measurements and correlation of grain orientation – modulus of elasticity and grain size – hardness
• Homogenization of the various evaluation zones using analytical and simulation-based methods

What you contribute

• You are a registered student in Chemnitz, Mittweida, Freiberg, Dresden, or the surrounding area.
• You have a grade point average (>2.0).
• You are studying materials science or a related field.
• You have some experience in the field of materials characterization and SEM.
• You are enthusiastic about current issues in applied research.
• You are self-motivated, communicative, and a team player.
• You have very good German and / or English language skills.

What we offer

• You will work on innovative and exciting international research projects, with the opportunity to contribute your own ideas.
• You will receive professional guidance and a diverse range of responsibilities.
• You will benefit from a collegial, pleasant, and motivating work environment.
• You will be part of a multidisciplinary team.
• You will have flexible working hours, allowing you to effectively balance your studies with practical work.

The weekly work hours are to be agreed upon on an individual basis and may not exceed 20 hours per week for student assistants. Remuneration according to the general works agreement for employing assistant staff.
We value and promote the diversity of our employees' skills and therefore welcome all applications – regardless of age, gender, nationality, ethnic and social origin, religion, ideology, disability, sexual orientation and identity. Severely disabled persons are given preference in the event of equal suitability. Our tasks are diverse and adaptable – for applicants with disabilities, we work together to find solutions that best promote their abilities.

With its focus on developing key technologies that are vital for the future and enabling the commercial utilization of this work by business and industry, Fraunhofer plays a central role in the innovation process. As a pioneer and catalyst for groundbreaking developments and scientific excellence, Fraunhofer helps shape society now and in the future.

Ready for a change? Then apply now and make a difference!

Please enclose your certificates and a current overview of your grades with your application.

Once we have received your online application, you will receive an automatic confirmation of receipt. We will then get back to you as soon as possible and let you know what happens next.

Fraunhofer Institute for Electronic Nano Systems ENAS

Requisition Number: 83720 Application Deadline: