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Czerny, Bernhard
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Official Name
Czerny, Bernhard
Main Affiliation
Akademische Titel
Mag. Dr.
Email
bernhard.czerny@fh-burgenland.at
ORCID
Scopus Author ID
36238795900
Status
staff
Research Outputs
Now showing 1 - 10 of 35
- PublicationStep-by-Step Building of a Four Dimensional Fatigue Compatible Regression Model including Frequencies(2021-12)
; 194 - PublicationInfluence of wirebond shape on its lifetime with application to frame connectionsThe subject of this study was to investigate the effect of different geometrical loop shapes on the reliability of 400 μm thick Al bond wires in IGBT modules by means of experimental and analytical methods. The experimental fatigue tests have been realized by linear cyclic displacements of 5-45 μm of the contact plates at 200 Hz and 20 kHz. Life time curves were obtained for bond wire connections with different loop heights, distances and angles with the main failure mechanism being wire bond heel cracking. Furthermore an analytical model was developed to calculate the effect of variation of geometrical shape parameters on the stress at different locations of the bond wire. This model can be used to make a preliminary geometry selection of the bond wire and to predict the force or stress at critical sites of the wire bond during stress tests. This model was validated with finite element analysis.
54Scopus© Citations 10 - PublicationElectro-thermal analysis of in situ vibration measurements on IGBT modules under operation conditions(Elsevier, 2012-09-17)
; 43Scopus© Citations 3 - PublicationHighly Accelerated Mechanical Lifetime Testing for Wire Bonds in Power ElectronicsThis article presents various experimental studies on fatigue evaluation of wire bond interconnects and interfaces in electronic devices using an accelerated mechanical fatigue testing system. This dedicated experimental setup is designed to induce fatigue failure in the weak sites of the wire bond by reproducing the thermomechanical failure modes occurring during operation. An exceptional highly test acceleration is achieved by increasing the mechanical testing frequency into the kHz regimen enabling the determination of lifetime curves in a very short time. A com parison of this method to conventional testing methods such as power cycling, a shear testing exploits the potential of customized accelerated mechanical testing. Exemplary studies on the degra dation and fatigue failure of heavy Al wire bonds typically used in power electronics and novel Cu wire bonds are presented and advantages and some restrictions of the proposed method are discussed.
95 - PublicationExperimental investigation of transient electrical, thermal and mechanical behavior of IGBT inverter modules during operation(Elsevier, 2013-05-26)
; 49Scopus© Citations 1 - PublicationA rapid test for reliability of heavy wire bondsBond-Drahtverbindungen müssen über mehrere Dekaden und unter hohen thermomechanischen Belastungen zuverlässig halten. Dafür sorgt ein Bondtester mit einem extrem schnellen automatischen Qualitätstest zur Lebensdauerbestimmung der Bond-Drahtverbindungen.
60 - PublicationA fast test technique for life time estimation of ultrasonically welded Cu-Cu interconnectsIn this research the quality of the interconnects of the ultrasonically welded Cu terminals to the Cu substrate in the IGBT-module has been investigated. An ultrasonic resonance fatigue system in combination with a laser Doppler vibrometer and a special specimen design was used for shear fatigue testing of these large ultrasonic Cu-Cu welds (about 0.5 cm2). Fatigue life curves up to 109 loading cycles were obtained in a very short period of time. Using this technique it was possible to evaluate the fatigue strength of these interconnects for the first time. The microstructural features of the interconnects were characterized and their crack growth behaviour was studied. Fracture analysis of the fatigued specimen shows that failure occur due to the propagation of the crack beneath the welding interface into the copper substrate. Additionally performed finite element simulations offer an insight into the stress and strain concentrations during the mechanical fatigue tests. As this method is not restricted to the welding geometry, material joints with larger interconnects can be tested likewise. Thus this new technique can be used as a practical and valid fatigue testing method for evaluation of various interconnects.
46Scopus© Citations 1 - PublicationInterface characterization of Cu-Cu ball bonds by a fast shear fatigue methodA highly accelerated shear fatigue testing method is presented to test the long-term reliability and reveal the bonded interface of thermosonic Cusingle bondCu ball bonds. The method is an adaptation to a new industrial fatigue tester (BAMFIT) and can be conducted without an intricate specimen preparation. This method induces mechanical cyclic shear stresses to the Cu nailhead in order to initiate fatigue fracture until lift-off, revealing the actual bonded interface. This study compares the fatigue resistance of Cu wire bonded to coarse and fine grained Cu and Al metallization. The fatigue experiments are accompanied by nano indentation tests, shear tests and finite element analysis. The fatigue results showed the best performance for Cu bonds on coarse grained Cu pads (metallization), followed by those bonded on fine grained Cu while the Cusingle bondAl nailheads failed at least a decade earlier than Cusingle bondCu bonds. Annealing the specimens prior to testing resulted in slight increases in the number of loading cycles to failure (Nf) for Cu bonds as well as for Cusingle bondAl bonds, while the scattering in Nf for Cu bonds increased. Nevertheless the calculated endurance limit of the fatigue data decreases with increasing annealing stages, due to a change in the fracture probability curve. With the ability to compare the fatigue behaviour of the bonded interface within minutes, this method is most suitable for rapid qualification at an early stage of development.
80Scopus© Citations 1 - PublicationFatigue life time modelling of Cu and Au fine wires(2018-05-25)
; 67Scopus© Citations 5 - PublicationWire bond degradation under thermo- and pure mechanical loading(Elsevier, 2017-09)
; 48Scopus© Citations 13