Thermo-mechanical analysis of bonding wires in IGBT modules under operating conditions

Czerny, Bernhard; Lederer, M.; Nagl, B.; Trnka, A.; Khatibi, Golta; Thoben, M.

doi:10.1016/j.microrel.2012.06.081

Cited by 75 publications

(27 citation statements)

References 4 publications

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“…For the loading condition of I ph3 128 A, the temperatures T ripple of the IGBT and the one of the diode cross over similar to the power losses P die in figure 7. This effect can also be observed at the mechanical LDV measurements as explain in [6]. At a loading current I ph3 of 320 A the temperature T ripple of the IGBT and the diode have a similar behavior for pulse frequencies f pulse .…”

Section: Electrical Considerationsupporting

confidence: 63%

“…Furthermore a thermal -structural coupled field Finite Element Analysis (FEA) was conducted. The boundary conditions and the execution details of the simulation are explained in [5] and [6]. The input values of the simulation are the total power losses P die , which are shown in figure 7 for all loading conditions.…”

Section: Thermo-mechanical Considerationmentioning

confidence: 99%

“…IGBT modules often operate at constant power levels for a long period of time, as e.g. in wind power stations [5,6]. During this period, at low inverter output frequencies, the components are exposed to a cyclic thermo-mechanical deformation due to the alternating current switching from the IGBT to the diode and back.…”

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confidence: 99%

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Electro-thermal analysis of in situ vibration measurements on IGBT modules under operation conditions

Nagl

Czerny

Lederer

et al. 2012

2012 4th Electronic System-Integration Technology Conference

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This paper discusses different application relevant electrical loading cases of an IGBT module of a power inverter. Thereby, different operation conditions such as pulse frequencies, inverter output currents and output frequencies, as well as two different operation modes are discussed. Each load case investigation is conducted by electrical, thermal, and in situ vibration measurements. Moreover, on the base of finite element analyses a deeper insight is gained into reliability relevant thermo-mechanical behavior. For this purpose an IGBT module is operated at a load of 30% to 80% of its nominal value in order to cause representative thermomechanical displacements of dies and bond wires. By applying an inverter output frequency in a range of 1 to 280 Hz a temperature ripple of up to 40 K on the dies and a vertical displacement of up to 9 µm on a bond wire is observed. These results are important to improve life-timepredictions. IntroductionIGBT (Insulated Gate Bipolar Transistor) power modules are often used in electronic power inverters. Due to the high voltage and current level, any switching operation results in local power loss peaks in the die causing internal stresses. These stresses can be divided into electrical, mechanical, and thermal. Due to the thermal mismatch of adjacent materials temperature variations in system components cause stresses at their interfaces [1]. These stresses are related to material dependent strain and are known as the main factor of thermomechanical fatigue [2]. This may result in a relevant degradation of the devices and affect reliability. IGBT modules often operate at constant power levels for a long period of time, as e.g. in wind power stations [5,6]. During this period, at low inverter output frequencies, the components are exposed to a cyclic thermo-mechanical deformation due to the alternating current switching from the IGBT to the diode and back. The operation frequency for this process can range from 0 Hz to 300 Hz. Especially in traction application an electrical braking until full stop (0 Hz) is requested frequently. Due to the low frequencies (≤ 5 Hz) during a longer period of time the periodic temperature T ripple during the inverter output time period 1/f output increases. The pulse frequency f pulse is usually 1 to 5 kHz. The time to thermal steady-state of the module is approximately 1 s. Therefore, the temperature differences in the IGBT package increase and decrease according to inverter output frequency f output which is often labeled as operation frequency. This effect causes higher stresses in the package and could influence the life time.

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Section: Electrical Considerationsupporting

confidence: 63%

Section: Thermo-mechanical Considerationmentioning

confidence: 99%

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Electro-thermal analysis of in situ vibration measurements on IGBT modules under operation conditions

Nagl

Czerny

Lederer

et al. 2012

2012 4th Electronic System-Integration Technology Conference

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“…6 Another factor to consider is the heterogeneous distribution of current on the die and within the wires. 40,41 This may explain the different rates of degradation observed at different locations.…”

Section: Interpretation and Analysis Of Tomography Resultsmentioning

confidence: 99%

Damage Evolution in Al Wire Bonds Subjected to a Junction Temperature Fluctuation of 30 K

Agyakwa

Yang

Arjmand

et al. 2016

Journal of Elec Materi

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Ultrasonically bonded heavy Al wires subjected to a small junction temperature fluctuation under power cycling from 40°C to 70°C were investigated using a non-destructive three-dimensional (3-D) x-ray tomography evaluation approach. The occurrence of irreversible deformation of the microstructure and wear-out under such conditions were demonstrated. The observed microstructures consist of interfacial and inter-granular cracks concentrated in zones of stress intensity, i.e., near heels and emanating from interface precracks. Interfacial voids were also observed within the bond interior. Degradation rates of 'first' and 'stitch' bonds are compared and contrasted. A correlative microscopy study combining perspectives from optical microscopy with the x-ray tomography results clarifies the damage observed. An estimation of lifetime is made from the results and discussed in the light of existing predictions.

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“…These connections are subjected to large thermo-mechanical loads due to the large difference in CTE of the housing and the substrates. Another source of thermal stresses is the temperature gradient since the semiconductors at the substrate are the main heat sources in such modules [3].…”

Section: Introductionmentioning

confidence: 99%

Influence of wirebond shape on its lifetime with application to frame connections

Czerny

Paul

Khatibi

et al. 2013

2013 14th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and

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The subject of this study was to investigate the effect of different geometrical loop shapes on the reliability of 400 /lm thick AI 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 /lm 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.

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Thermo-mechanical analysis of bonding wires in IGBT modules under operating conditions

Cited by 75 publications

References 4 publications

Electro-thermal analysis of in situ vibration measurements on IGBT modules under operation conditions

Electro-thermal analysis of in situ vibration measurements on IGBT modules under operation conditions

Damage Evolution in Al Wire Bonds Subjected to a Junction Temperature Fluctuation of 30 K

Influence of wirebond shape on its lifetime with application to frame connections

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