Thermal Characterization of Electronic Packages Using the Nyquist Plot of the Thermal Impedance
27 Nov 2007-IEEE Transactions on Components and Packaging Technologies (IEEE)-Vol. 30, Iss: 4, pp 660-665
TL;DR: In this paper, it was shown that if the thermal impedance Zth(jw) of an electronic package is represented in a Nyquist plot, the curve obtained can be fitted very well to a combination of a few (n) circles, n varying between 2 and a maximum of 5.
Abstract: It will be shown in this contribution that if the thermal impedance Zth(jw)of an electronic package is represented in a Nyquist plot, the curve obtained can be fitted very well to a combination of a few (n) circles, n varying between 2 and a maximum of 5. For each of these circles, it is sufficient to know the radius and the coordinates of the center point or just three parameters. With 3n parameters the entire behavior of the impedance can be represented and consequently, the dynamic behavior as well.
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TL;DR: In this article, the thermal impedance of a silicon substrate with a uniform heat source on top was calculated numerically using the boundary element method, using two circular arcs for the lower frequency arc and for the high frequency arc.
44 citations
16 Mar 2014
TL;DR: In this article, an Effective Heat Propagation Path (EHPP)-based online adaptive thermal model for IGBT modules is proposed to quantify the impact of substrate solder cracks on the heat propagation inside the IGBT module.
Abstract: The information of junction temperature is crucial for operation management of IGBT modules In practice, junction temperature is typically estimated by using an electrothermal model IGBT modules are subject to various aging processes during operation, some of which, eg substrate solder crack, changes the thermal impedance of an IGBT module However, in the literature little work has included the aging effects into online thermal behavior modeling of IGBT modules This paper proposes an Effective Heat Propagation Path (EHPP)-based online adaptive thermal model for IGBT modules, where the EHPP is proposed to quantify the impact of substrate solder cracks on the heat propagation inside the IGBT modules A straightforward relationship between substrate solder crack and the degree of nonuniformity of case temperature distribution is established Based on the EHPP, the parameters of a thermal network, eg, a Cauer thermal network, are adjusted online to track the thermal behavior changes of the IGBT modules caused by substrate solder cracks, leading to an adaptive thermal model The proposed adaptive thermal model is validated by comparing with finite element analysis (FEA) simulation results for a commercial IGBT module
42 citations
TL;DR: In this paper, the thermal behavior of a laboratory model for an underground cable has been investigated experimentally and the results are represented by thermal impedances, which are then used to obtain the thermal time constant distribution and the structure functions.
35 citations
TL;DR: In this paper, a downscaled laboratory model for an underground cable has been investigated experimentally with respect to these parameters, and a dynamic thermal analysis has been conducted to provide the complex thermal impedance, thermal time constant distribution and cumulative structure function.
30 citations
TL;DR: In this paper, the concept of thermal impedance is utilized in order to determine the thermal properties of a power cable buried in earth with respect to the burial depth, and a theoretical analysis is conducted concerning the calculation of the thermal impedance for the problem under study.
28 citations
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TL;DR: In this paper, the locus of the dielectric constant in the complex plane was defined to be a circular arc with end points on the axis of reals and center below this axis.
Abstract: The dispersion and absorption of a considerable number of liquid and dielectrics are represented by the empirical formula e*−e∞=(e0−e∞)/[1+(iωτ0)1−α]. In this equation, e* is the complex dielectric constant, e0 and e∞ are the ``static'' and ``infinite frequency'' dielectric constants, ω=2π times the frequency, and τ0 is a generalized relaxation time. The parameter α can assume values between 0 and 1, the former value giving the result of Debye for polar dielectrics. The expression (1) requires that the locus of the dielectric constant in the complex plane be a circular arc with end points on the axis of reals and center below this axis.If a distribution of relaxation times is assumed to account for Eq. (1), it is possible to calculate the necessary distribution function by the method of Fuoss and Kirkwood. It is, however, difficult to understand the physical significance of this formal result.If a dielectric satisfying Eq. (1) is represented by a three‐element electrical circuit, the mechanism responsible...
8,409 citations
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01 Jan 1983TL;DR: In this paper, a broad-brush view of dielectric relaxation in solids is presented, making use of the existence of a universality of Dielectric response regardless of a wide diversity of materials and structures with dipolar as well as charge-carrier polarization.
Abstract: This review presents a wide-ranging broad-brush picture of dielectric relaxation in solids, making use of the existence of a `universality' of dielectric response regardless of a wide diversity of materials and structures, with dipolar as well as charge-carrier polarization. The review of the experimental evidence includes extreme examples of highly conducting materials showing strongly dispersive behaviour, low-loss materials with a `flat', frequency-independent susceptibility, dipolar loss peaks etc. The surprising conclusion is that despite the evident complexity of the relaxation processes certain very simple relations prevail and this leads to a better insight into the nature of these processes.
4,752 citations
620 citations
TL;DR: In this paper, a deconvolution operation performed in the logarithmic time domain gives the "timeconstant spectrum" of the chip-case-ambient thermal structure.
Abstract: A new method has been developed in order to identify the thermal environment of a semiconductor device chip. The identification algorithm operates on the thermal transient response of the device recorded during a one-shot pulse measurement. A deconvolution operation performed in the logarithmic time domain gives the “time-constant spectrum” of the chip-case-ambient thermal structure. A further transformation leads to the “structure-function” that is the cross-sectional area of the heat conducting materials vs thermal resistance (related to the heat source). The structure function has a good and quantitatively evaluable correspondence to the physical chip environment and heat conducting structure. Separating the different regions of the heat-flow path (corresponding to the chip, bond, header, case) as well as the detection of eventual heat-transport irregularities (mounting errors) is possible.
419 citations