Simulation of shear tests on bond wedges for the assessment of the bonding quality of new thick wires on aluminum basis

• Applicant: Professor Dr.-Ing. Martin Schneider-Ramelow
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins ; Computer-Aided Design of Materials and Simulation of Materials Behaviour from Atomic to Microscopic Scale
• Term: from 2021 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456843234

The objective of this project is to describe the shear test used for quality assessment of thick wire bonds (wedges) by means of damage mechanics models and to correlate these with real tests. The tests and the models shall lead to a scientific interpretation and understanding of the increasing development of damage as well as of the corresponding hardening. By doing so conclusions regarding the material and process-specific influences of new wire materials on the development of shear codes shall be drawn, in order to make a contribution to the objective assessment of bond quality with new wire materials. In the experimental part wedges of fair quality of three types of wire of different microstructure and mechanical properties on OF-copper (CW008A) substrates will be produced and delivered in sufficient quantity for further metallurgical investigations and shear tests. As wire materials serve: (a) Al-high purity-standard wire Al H11, (b) fine grained, high strength Mg alloyed Al-wire: AlMg0,5, (c) high strength bimetal wire: Al-coated Cu-wire of ca. 30 µm Al-coating thickness (CuCorAl). This will serve as data resource for the quantitative correlation and verification of the theoretical models. Hence, on the simulation side successively refined damage models for the simulation of the formation of specific shear codes will be applied, namely (a) elasto-plastic modeling and a comparative analysis based on ideal plasticity, (b) implementation of a scalar damage parameter, (c) implementation of a damage tensor second rank following up on a previous DFG project. Finally the damage models will be exemplarily applied to technically relevant application cases in order to demonstrate their transferability to substrates and semiconductor materials with their corresponding metallizations used in the market and to allow for prognosis of future development variants.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Wolfgang H. Müller