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Low-temperature silver sintering technology, which has been proven to be a promising die-attach solution, was extended to bonding large substrates. Strong bonding strengths for substrates greater than 25 mm × 50 mm were achieved by sintering a nanosilver paste at temperatures below 270°C with less than 5 MPa pressure. To characterize thermal performance of the substrate-attach interface, we applied...
In this paper a non-invasive thermometric system for the measurement of the temperature of fluids in pipes based on the dual heat flux method is presented. The proposed solution is a possible alternative to the employment of thermowells in industrial applications. The proposed sensing system, is based on the dual heat flux method, a technique used in biomedical field. The applicability of such a measurement...
This paper presents an improved thermal equivalent circuit model which provides an accurate thermal and loss estimation for integrated power modules. Thermal analysis is a critical issue for power electronic systems, it estimates the thermal performance of power devices and enables a flexible converter design. Unlike the conventional thermal models, the modified analytical thermal model takes the...
This paper discuses on the practical example the problem of thermal modelling of power LEDs used in luminaries. The proper determination of the thermal resistance is crucial for accurate computation of the device junction temperature, which determines the device operating parameters. Here, this problem is illustrated based on the analysis of power LED heating curve measurements taken for various amount...
This paper presents in detail the design and the practical realization of a dedicated stand for the transient thermal measurement of electronic devices. The stand is equipped with the dual cold plate cooling system containing thermoelectric modules which allow the precise control of boundary conditions, hence enabling a practical realization of the variable thermal resistance. This stand was thoroughly...
This paper proposes a thermal network parameter estimation method to find RC parameters of the Cauer network using cooling curve of IGBT module. The solutions are developed by exploiting the relationship between thermal network parameters and time constants of junction temperature response curves. Experimental tests are performed to validate the accuracy of the developed method. Advantages of the...
Screening for optimal thermal performance of semiconductor wafers was developed based on a noninvasive thermo-reflectance technique. Temperature changes of the wafer surface, induced by a nanosecond pulsed laser absorbed into the near surface region, allows to extract critical thermal parameters such as thermal boundary resistances between epilayers or epilayers and substrate. These affect channel...
The thermal performance of a flat-plate closed-loop pulsating heat pipe (PHP) is experimentally obtained. The PHP is manufactured by means of CNC-milling and vacuum brazing of a stainless steel 316L bottom plate and lid. Each channel of the PHP has a 2∗2 mm2 square cross section. In total 12 channels (6 turns) fit in the 50∗200 mm2 effective area of the PHP. During the experimental investigation,...
In power switch assemblies the heat is removed through laminate stacks containing thermal interface materials (TIM). Some information on a TIM layer quality can be obtained by dedicated thermal conductivity testers, but the in-situ behavior of a TIM in the assembly may significantly differ. Thermal transient testing yields partial thermal resistances of these layers in the stack and can provide temperature...
Ultrasound probe cable must efficiently dissipate the heat of piezoelectric elements in a probe head. We evaluated the heat transfer by measuring thermal resistance with various conditions. By simply changing the braid shielding material inside the cable and by implementing a thermal connection method to the heat source, we found that at least 40% of the heat could be efficiently transferred to the...
Ultrasound probe cable for 3D and 4D designs must efficiently dissipate the higher heat of probe head piezoelectric elements. A typical ultrasound probe cable consists of many micro-coaxial cables with an overall shield and jacket. By simply changing materials and termination methods, a significant reduction of heat can be transferred and dissipated through the cable. We will show our analysis of...
Heat transport within high aspect ratio, rectangular mm-scale channels of air cooled heat sinks is significantly enhanced by deliberate formation of unsteady small-scale vortical motions induced by autonomous, aeroelastic fluttering of cantilevered planar thin-film reeds. The interactions between the reed and the channel flow are exploited to overcome conventional limits of forced convection heat...
Thermal resistance and temperature distribution for high-power AlGaInN LED chip-on-board arrays in blue and white versions were measured by different methods and tools. The p-n junction temperature was determined through measuring a temperature-dependent forward voltage drop on the p-n junction, at a low measuring current after applying a high heating current. Furthermore, the infrared thermal imaging...
This work deals with an overall concept of a 3D-stack enabling to produce a directly pluggable high voltage power LED. Using a dedicated silicon vehicle test, a thermal study is carried out with an extensive thermal modelling, optimization, assembly process and Infrared thermal characterization. It is shown that the main thermal issues are due to the presence of the flip chip interconnection layer...
This paper discusses the problem offitting parameters of a detailed circuit thermal model when the complete data on problem geometry or material properties are not available. The problem is illustrated based on a practical example of a test hybrid circuit. Unknown model parameter values are determined here from dynamic temperature measurement results which were processed employing the Network Identification...
In this study, it is found that the temperature measurement using body diode of SiC-MOSFET is greatly affected by the bias voltage between gate and source, unlike using body diode of Si-MOSFET. We introduce a method that it is possible to measure the junction temperature correctly by applying a suitable negative bias between G-S. Hence, the heat resistance evaluation method for the SiC power module...
Modulation method and the device for thermal impedance measuring of power COB LEDs and measurement results are described. The measurements were performed by generic modulation method that implies heating a device under test by power varying harmonically. A pulse sequence of heating current, with the pulse length varying harmonically, is passed through the device under test. The p-n junction temperature...
Operation of LEDs is highly affected by their junction temperature. However, for proper thermal characterisation a well fitted K-factor function is needed within its validity range. Correction for the parallel thermal resistance during thermal transient testing also needs special care. This paper focuses on the issues of applying a correct K-factor value or higher polynomial fit to the temperature...
The thermal finite element model of the power module based on the actual physical conditions is not easy to be consistent with the experimental results, limited by the accuracy of the input conditions. In this paper, a method of calibrating the transient thermal finite element model using the measured thermal structural function is proposed and practiced. The structural functions derived from the...
Recent advances in transportation and new energy fields such as electric vehicles and power trains requires integrated power modules with increasing power input/outputs with high reliability. The next generation of integrated power inverter would have multiple MOSFET devices for demanding operations, leading to unprecedented challenges in thermal management, materials and reliability. In this work,...
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