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Influence of R-Ratio on Fatigue of Aluminum Bonding Wires

  • Bonding wires made of aluminum are the most used materials for the transmission of electrical signals in power electronic devices. During operation, different cyclic mechanical and thermal stresses can lead to fatigue loads and a failure of the bonding wires. A prediction or prevention of the wire failure is not yet possible by design for all cases. The following work presents meaningful fatigue tests in small wire dimensions and investigates the influence of the R-ratio on the lifetime of two different aluminum wires with a diameter of 300 μm each. The experiments show very reproducible fatigue results with ductile failure behavior. The endurable stress amplitude decreases linearly with an increasing stress ratio, which can be displayed by a Smith diagram, even though the applied maximum stresses exceed the initial yield stresses determined by tensile tests. A scaling of the fatigue results by the tensile strength indicates that the fatigue level is significantly influenced by the strength of the material. Due to the very consistent findings, the development of a generalized fatigue model for predicting the lifetime of bonding wires with an arbitrary loading situation seems to be possible and will be further investigated.

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Document Type:Article
Author:Cassandra Moers, Christian Dresbach
Parent Title (English):Metals
Article Number:9
Number of pages:10
Place of publication:Basel
Publishing Institution:Hochschule Bonn-Rhein-Sieg
Date of first publication:2022/12/20
Copyright:© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license
Funding:This research was partially funded by the German Federal Ministry of Education and Research in the project WireLife in the program FH-Kooperativ under the funding code 13FH544KX0 and by the Graduate Institute of the University of Applied Science Bonn-Rhein-Sieg and the Institute of Technology, Resource and Energy-efficient Engineering.
Keyword:R-ratio; aluminum bonding wire; power electronics; small-scale fatigue testing
Departments, institutes and facilities:Fachbereich Angewandte Naturwissenschaften
Institut für Technik, Ressourcenschonung und Energieeffizienz (TREE)
Projects:FH-Kooperativ 2-2020: Lebensdauer neuer Aluminiumdrähte der Leistungselektronik (DE/BMBF/13FH544KX0)
Dewey Decimal Classification (DDC):6 Technik, Medizin, angewandte Wissenschaften / 67 Industrielle Fertigung / 671 Verfahren der Metallverarbeitung und Rohprodukte aus Metall
Entry in this database:2023/01/04
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International