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17. Thermal Onboard Detection of Voids in the Solder Layer Between Power Semiconductor and PCB

Author

Jahn, Nils and Pfost, Martin

Abstract

In this work, a concept for the detection of defects in the solder layer between a power semiconductor and the printed circuit board (PCB) is proposed. Four temperature sensors in the form of discrete diodes are placed adjacent to the semiconductor. Multiple test devices with varying fault patterns in the solder layer are subjected to a power pulse, and the temperature response at the sensors is recorded and evaluated with two different methods. Conclusions about the existence, growth, and position of solder defects are drawn from the measured data. The sensitivity and usability of the concept are discussed.

Published
2023
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18. A comprehensive analytical description of the asymmetric active snubber.

Author

Schlüter, Michael and Pfost, Martin

Subjects
BREAKDOWN voltage, SEMICONDUCTOR materials, OVERVOLTAGE, SILICON carbide, ELECTRIC inductance, THYRISTORS
Abstract

Power modules for several hundred amperes suffer from a high stray inductance compared to discrete setups at similar current density. The use of silicon carbide in such modules is beneficial but due to the high stray inductance, the switching speed must be reduced to keep the voltage overshoot below breakdown voltage. As a result, the semiconductor material cannot be fully utilised. To improve the utilisation in terms of power output, by strong over‐voltage reduction, reduced ringing, and highest switching speeds an asymmetric active snubber was introduced. This work targets an improved understanding of the active snubber by deriving analytical models to describe the behaviour during turn‐on and turn‐off and elaborate optimisation opportunities. The models are compared to measurements for validation and an improved loss estimation is derived as well as a prediction of the snubber voltage. Different modes of operation are investigated and compared to a similar DC‐snubber setup. Finally, the model is used to pre‐calculate the timing for optimal operation. [ABSTRACT FROM AUTHOR]

Published
2023
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21. Innovationen zur Entwicklung von Turbogeneratoren zur Unterstützung der Energiewende 2.0, Teilvorhaben: Entwicklung dämpfender Strukturmaterialien zur Verbesserung der thermomechanischen und dynamisch-mechanischen Betriebseigenschaften im Ständerwickelkopf : Schlussbericht : Laufzeit: 01.07.2020-30.06.2021

Author

Pfost, Martin, Lange, Sebastian, and Ntourmas, Felix

Subjects
Mechanical engineering, power engineering
Abstract

Illustrationen, Diagramme

Published
2021
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27. Methods for measurement and simulation of weak substrate coupling in high-speed bipolar ICs

Author

Steiner, Wolfgang, Pfost, Martin, Rein, Hans-Martin, Sturmer, Anton, and Schuppen, Andreas

Subjects
Integrated circuits -- Wafer-scale integration, Signal detection (Electronics) -- Methods, Simulation methods -- Usage, Business, Computers, Electronics, Electronics and electrical industries
Abstract

On-wafer measurements of very weak substrate coupling in high-speed integrated circuits (ICs) at high frequencies suffer from the direct crosstalk between the input and output RF probes. Two alternative methods to reduce this effect are presented and compared. The first one is based on an advanced deembedding method that eliminates the crosstalk between the RF probes after measurement. The second method utilizes an on-chip broad-band amplifier between the input probe and the substrate test structure. Thus, for a given signal amplitude at the output probe, the amplitude of the input signal can be reduced, resulting in less distortion of the output signal by the crosstalk via the probes. Both methods are compared and verified by measurements up to about 20 GHz even at substrate coupling impedances as high as 0.5 M[ohm] (corresponding to -80 dB in a 50-[ohm] system). For this, several substrate test structures (some with the 20-GHz on-chip amplifier) have been designed and fabricated in an SiGe bipolar production technology with 20-[ohm]cm substrate resistivity. The measurement results agree well with simulation results using our substrate simulator SUSI. As a consequence, the inflexible, expensive, and time-consuming way to determine substrate coupling experimentally is no longer required in future IC designs--not even at very weak coupling and high frequencies. In this work, however, the proposed measuring methods had to be applied to verify the suitability of substrate simulation (with SUSI) under extreme conditions. Index Terms--On-wafer measurement techniques, substrate coupling, substrate coupling simulation.

Published
2002

34. Heat dissipation in epoxy/amine-based gradient composites with alumina particles

Author

Morak, Matthias, Marx, Philipp, Gschwandl, Mario, Fuchs, Peter Filipp, Pfost, Martin, and Wiesbrock, Frank

Subjects
Finite-Elemente-Methode, Kunststoffverarbeitung, Mikroelektronik, Gradient composite, Epoxy/amine resin, Thermal conductivity, Alumina particles, Thermal management, Wärmeübertragung
Abstract

For the design of the next generation of microelectronic packages, thermal management is one of the key aspects and must be met by the development of polymers with enhanced thermal conductivity. While all polymer classes show a very low thermal conductivity, this shortcoming can be compensated for by the addition of fillers, yielding polymer-based composite materials with high thermal conductivity. The inorganic fillers, however, are often available only in submicron- and micron-scaled dimensions and, consequently, can sediment during the curing reaction of the polymer matrix. In this study, an epoxy/amine resin was filled with nano- and submicron-scaled alumina particles, yielding a gradient composite. It was found that the thermal conductivity according to laser flash analysis of a sliced specimen ranged from 0.25 to 0.45 W·m−1·K−1 at room temperature. If the thermal conductivity of an uncut specimen was measured with a guarded heat flow meter, the ‘averaged’ thermal conductivity was measured to be only 0.25 W·m−1·K−1. Finite element analysis revealed that the heat dissipation through a gradient composite was of intermediate speed in comparison with homogeneous composites exhibiting a non-gradient thermal conductivity of 0.25 and 0.45 W·m−1·K−1., Polymers;Jg.: 10, Heft: 10 | S. 1131-1-1131-13

Published
2018
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