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Classical approaches to the 3D thermal simulation of electronic systems require assumptions regarding the amount of power dissipated and its distribution. Errors in such assumptions are a leading cause of resulting errors in temperature rise predictions. Although 3D electro-thermal simulations can be applied; where electrical boundary conditions are specified and current density, electrical potential...
The design of power electronics modules has always been carried out with major focus on product reliability. As the chip sizes and module sizes shrink, but the power dissipation remains constant or even increases, the growing power densities create thermal problems which make designers explore new die attach, substrate and bonding technologies, bringing thermal design to its limits. On the other hand...
The design of power electronics modules and power packages is heavily influenced by thermal concerns. New substrate materials, thinner and thermally more conductive attachment materials are used to decrease the thermal resistance of a given module. When a new material or technology is applied, its reliability has to be tested thoroughly before the module can be considered for production. The reliability...
Power modules are used in many of today's applications: automotive, renewable energy resources, and railway traction. The power module market will continue to grow as the industry is going towards zero carbon emissions. To ensure those products last 15 to 30 years, reliability of the power modules is extremely important. Design for reliability is not an obvious task, as the current trends include...
In power electronics there is an increasing need for accurate lifetime prediction. The results of power cycling tests are widely used as input data for the lifetime calculation. The general method of power cycling is described in the JESD22-A122 JEDEC standard, however as the industry has made significant progress in power module design and reliability testing ever since the standard was published...
Die attach degradation and bond wire damage are common failure modes in power electronics components. Power cycling testing is an effective way to trigger them, and combined with effective measurement technologies also to track their development while the pulses are applied. In both cases the assessment can be done based on voltage measurements. In case of bond wire degradation the collector-emitter...
Performing active power cycling tests is a commonly used method in the power electronics industry to detect different failure mechanisms in a power device, or to get information on their expected life time. The two major failure mechanisms triggered this way includes bond wire degradation or cracks and die attach problems. During the power cycling test process it is very valuable to detect these failures...
Power cycling is a widely used accelerated lifetime testing method to evaluate the reliability of power modules and discrete components. Based on the accelerated test results one can deduce the lifetime of these devices in normal operation conditions. Although, we have to be careful, because not only the initial parameters, but the control strategy used during the cycling tests may also affect the...
Thermal transient testing is the industry de-facto test method for the identification of junction temperatures and structural defects inside semiconductor devices. Unfortunately, at the beginning of the thermal transient curve in each case an electric effect can be observed, which appears immediately as the unit power step takes place. This electric effect covers the initial phase of thermal transient,...
In this article we investigate the different failure mechanisms in IGBT modules as a result of power cycling tests. The power cycling is carried out with different control strategies, such as constant current load, constant power and constant junction temperature. With the continuous monitoring of the tested device voltage, junction temperatures and periodic thermal transient tests, the crack of the...
This article describes a complex measurement and simulation based characterization method of high current IGBT modules. The method begins with thermal transient tests aimed at the investigation of the thermal behavior of the module and the creation of a thermal map of the heat conduction path using structure functions. This information can later be used for different purposes, such as the calibration...
This article describes a possible method to assess the long-time behaviour of IGBT modules using the combination of power cycles to stress the devices and thermal transient testing to monitor possible die-attach degradation. The failure of an IGBT module is a complex phenomenon; it consists of thermal, electrical and thermo-mechanical effects. After a theoretical overview of the possible mechanisms,...
This paper investigates the influence of nonlinearities in boundary conditions on thermal transients as well as their impact on the values of electronic system compact thermal model elements. The discussions in the paper are based on practical examples where thermal responses of a power device are recorded in various boundary conditions for different values of dissipated power. Then, the measurement...
In this paper, we describe a study in which the thermal performance data of Theta jc (Rth-JC), Theta ja (Rth-JA), and structure functions of a flip-chip ball grid array device with heat spreader, fcBGA-H, was measured. For Rth-JC, various boundary conditions for the thermal resistance modeling were considered and are discussed here. A transient measurement method was used to obtain the temperature...
Experimentally derived structure functions can be used to provide insights into the thermal resistances and capacitances heat experiences as it travels from a die through and beyond an IC package. A 3D “detailed” numerical model of the package that purports to explicitly represent the internal construction of the package requires material properties and geometric sizes to be accurately specified....
In this paper we first describe a thermal interface material measurement methodology based on thermal transient testing. Measurement examples on different types of TIM materials are shown and guidelines are given, how the tests should be carried out to achieve the highest possible accuracy. Finally we give recommendations on what types of materials have proven for us to be the best candidates to be...
In this paper we review the history of the static (continuous) and dynamic (pulsed) test methods described in JEDEC JESD51-1 [1]. Written in 1995, there has not been, to date and to the knowledge of the authors, any systematic review to these different approaches to the transient thermal testing of packaged ICs and LEDs. Commercially available and in-house test equipment perform either transient thermal...
In this paper the aspects of thermal interface material characterization are discussed from a practical point of view. A novel method based on existing measurement standards is introduced for a quick and repeatable thermal conductivity measurement of nanoparticle-based thermal greases. The effect of the surface roughness of the DUT fixture is evaluated, and a method is introduced for the long-term...
In this paper two possible ways are investigated to create accurate thermal models without having validated information on the thermal properties of the applied thermal interface materials. One way is the calibration of a detailed numerical thermal model based on the physical information which can be derived from experimental structure functions. In the paper we show a complete calibration procedure...
In this paper the possibility of generating a compact thermal model based on thermal transient measurements is discussed and evaluated. A case study of a power diode in a cylindrical-shaped copper package is shown. The detailed model of the package is built and simulated in a CFD based thermal simulator software. The measurement results are compared to the results of the simulations and after some...
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