Power cycling tests with online junction temperature measurement are well established for IGBTs, MOSFETs and diodes, standards applied in industry and at research facilities are currently emerging. However, for thyristors, recent intense power cycling reliability studies are unknown. In this work, an application-close test method with alternating load current and online temperature measurement based on two temperature sensitive-parameter using VGC (TJ) and VAC (TJ) for thyristor power modules is introduced. First test results of power cycling tests with direct and alternating load current are presented.

In this paper, several power cycling tests under single or combined test conditions were undertaken to investigate the applicability of linear cumulative damage theory in the lifetime prediction of power semiconductor devices. The validity of this theory was verified by an experimental method for one lifetime limit, which is an increase of forward voltage at load current by 5%. The corresponding failure mechanism is the degradation of bond wire contacts.

A method for remaining lifetime determination of power modules is presented. The bond shear force of bond wires after certain power cycles was compared to power cycling test results. A difference in remaining lifetime determination of approximately 50 % was found. The work focusses on elaboration of a model of dependency of remaining shear force to the number of power cycles as well as the validity of power cycling tests results for remaining lifetime statements. A further indicator, scanning acoustic microscopy of substrate solder, is investigated to determine the relation between decreasing area of solder connection and remaining lifetime.

The evaluation of power cycling results needs correct measurement of the course of thermal resistance. Hence an accurate online measurement of the junction temperature is necessary. Different measurement and power cycling methods were evaluated. The method of measuring the voltage drop of the SiC MOSFET body diode pn-junction at low measurement current with sufficient negative gate-voltage was found most suitable one. In addition power losses during power cycling test should be generated in forward MOSFET-mode at high positive gate-voltage. Otherwise test results will not be application conform.

In standard power cycling tests, forward conduction generates heat in the die and therefore the thermomechanical stress in the package. In application, however, a significant part of the power losses are switching losses, so that the load current is lower than in standard power cycling test, for an equal temperature swing. A new concept for power cycling tests is presented, which allows the generation of switching losses in addition to conduction losses. This concept closer to the real application. The circuit still uses a low voltage power source, while maintaining an accurate measurement of the virtual junction temperature. First test results of IGBTs in standard module technology and SiC MOSFETs in discrete TO-247 housing indicate no significant difference in results from standard power cycling tests. The new method was successfully applied to low voltage Si MOSFETs, which is for the first time applied to such a power cycling test under conditions where switching losses dominate.

•Inverter-like operated IGBTs showed expected lifetime for short on-period of 60ms.•New test bench concept for heating by forward and switching losses at low DC link voltage•Dimensioning and required circuitry explained

High measurement accuracy is the basis for a precise determination of the junction temperature Tj. Temperature measurement can be performed by means of temperature sensitive parameters (TSP) using the VCE(T)-method, however, internal semiconductor processes like the removal of stored charge in bipolar devices have to be respected. The aim of this work is to determine the earliest time point of accurate measurement tMD after switching off, as well as dependencies on device voltage classes and applied battery voltage. Measurement results are confirmed by performing the simulation with Sentaurus TCAD. Dependencies of delay tMD on temperature, applied measurement current and battery voltage are demonstrated for IGBT and silicon diode.

In this article, a new method to measure fatigue mechanisms in standard module technology of semiconductor power devices is investigated. Power modules are used in a wide field of applications, like the automotive industry or as switch converter in wind turbines. Over a certain amount of time the modules will degrade and fail. To detect this degradation we used the principle of acoustic emission. The Acoustic Emission Method can be the first approach for On line Measurement of the State-of-Health of a Power module. Our results have shown that observing the ageing process of the whole power module is possible with this method.

This paper discusses power cycling as a method to evaluate the reliability of interconnections in power electronic devices. While the approach proved a reliable tool for investigating the potential of improvement for alternative interconnect technologies and rejecting design flaws, precise estimations about lifetime in the field are still challenging. Many questions are still in discussion, such as ultra-high cycle fatigue, applicability of Miner's rule, or the influence of on-time and cross-effects with mechanical shocks or humidity. This leaves application engineers with a blurred safety margin. In the following basic considerations of power cycling are described. The introduction shows two applications with different load profiles. Section 2 explains methods of temperature measurement. In Section 3 theoretical requirements for measurement accuracy are given, the obstacle minimal measurement delay and possible workarounds are evaluated. Finally aging effects and their acceleration in different devices are discussed in Section 4. In the conclusion suggestions for power cycling methods and a revision of the end-of-life criteria are made.

A power cycling test-bench for short load pulse duration in the millisecond range has been developed. This new setup with a cross regulator is in addition capable to test IGBTs and diodes of different manufacturers with the same desired combination of load pulse duration ton and junction temperature swing DeltaTj at the same time. Series of power cycling tests can be performed on this test-bench to build up new empirical lifetime models for IGBT modules. The focus lies on the impact of the short load pulse duration and small junction temperature swing on the power cycling capability.

This paper discusses the limitation in measurement accuracy of junction temperature measurements of bipolar devices. A limiting factor the measurement delay, caused by slow removal of charge carriers, was investigated by single pulse measurements and evaluated by simulations. A minimal measurement delay of 650μs was found for a 6,5kV IGBT at high temperature.

The reliability of discrete power semiconductor packages is getting more and more important in regard to the increasing number of power applications in the low power range. Therefore it is necessary to get more information and details on reliability of discrete packages and systems by performing reliability tests as well as simulations. In this paper the chosen approach and first results of simulations and tests are described on D2Pak and CanPAK systems as often used discrete power semiconductor packages.

This paper discusses how the square-root-t method improves the measurement of the virtual junction temperature Tvj in a power cycling test setup. By applying this method, the measurement becomes more tolerant to measurement delays and EMC noise, thus it enables to sharpen the basis of life time estimations. However the virtual junction temperature remains a one dimensional mapping of the three-dimensional temperature gradient which combined with CTE-mismatch induces stress in the interconnection materials. Therefore Tvj-measurement data are compared to statements found in IR-images.

The presented thermal impedance spectroscopy of power modules simplifies significantly the failure analysis of power modules. It enables online observation of degradation within the cooling path with detailed information about failure mechanisms. The degradation of certain layer within the power module is detected by observation of Z th parameters. Several tests results are compared with analysis of the scanning acoustic microscope.