Junction Temperature Calculation Research Articles

Review of Thyristor Junction Temperature Calculation Methods

The thyristor has been widely used in many fields since it has been invented, and has promoted the development of the DC transmission technology rapidly. The increasing temperature of its junction may cause serious hazards. Because of this, a variety of methods that can obtain the junction temperature has been summarized in this paper, such as the indirect measurement method, the direct measurement method, the equivalent thermal impedance network method and the numerical calculation method, etc. Summaries have been made in different occasions which these methods were applied. It also compared the advantages and disadvantages of each method and pointed out the developing trends and researching directions in the future.

Accurate Calculation of Junction Temperature of HBTs

Heterojunction bipolar transistors (HBTs) offer high power and linearity for microwave and mixed-signal applications. The large-signal performance of an HBT is frequently limited by the maximum operating current, which is set by thermal considerations. Hence, an accurate determination of the junction temperature in HBT devices and the corresponding microwave/millimeter-wave monolithic integrated circuits (MMICs)/DAC is critical to achieving maximum performance while maintaining reliable operation. An original accurate closed-form expression is presented for the thermal resistance of HBT structures from which the maximum junction temperature can be determined. The model's validity is verified by numerical simulations and experimental data. The model agrees with two sets of experimental data to within 2% and 6%. The closed-form solution offers device and MMIC designers a fast assessment of the performance and reliability of devices and circuits. Circuit optimization for required performance can be achieved efficiently.

Application of multiobjective optimization in selection of printed wiring boards

This paper presents an application of multiobjective optimization in optimal selection of number of signal layers in printed wiring board (PWB). The criteria considered in optimization are: cost, electrical performance, and reliability. The reliability of system is influenced by the operating temperature, which is determined by the power dissipated in parts placed on the board, ambient temperature, and cooling technology. In evaluating cooling and calculation of junction temperature both heat conduction through the board and forced air cooling are considered. Designers have to deal with multiple, conflicting criteria because of variety of requirements that packaging should meet. However, sophisticated methods developed for multiobjective optimization are not yet used in packaging design. This paper describes some of the methods used in solving multicriteria optimization and gives an example of application to design of PWB. The weighting method is applied to find the optimal solution first. The graphical form of optimality of different weights for different criteria is presented. The distance based methods, which include l/sub 1/-distance, l/sub 2/-distance, l/sub /spl infin//-distance, and the geometric distance method, are also applied to determine the optimal number of signal layers. The results from different methods are compared and discussed.

Evaluation of analytical models for thermal analysis and design of electronic packages

The objective of this study is to evaluate the use of several analytical compact heat transfer models for thermal design, optimization, and performance evaluation in electronic packaging. A model for heat spreading in orthotropic materials is developed. The developed model is used in conjunction with the other available heat transfer models in a resistance network for calculation of heat transfer rate and junction temperatures in a multi-chip module (MCM). Refrigeration cooled MCM of an IBM server is used to illustrate the methodology. Results of the analytical model and resistance network analysis are compared with a numerical solution. Capability of the analytical model in predicting the thermal field is discussed and effectiveness of using the analytical models in thermal design and optimization of electronic packages is demonstrated.

Implementation and validation of a new thermal model for analysis, design, and characterization of multichip power electronics devices

This paper presents a new electrothermal model for the analysis, design and characterization of multichip power electronics devices. This model allows the junction temperature calculation for devices in which several chips are thermally interacting. At the beginning of the paper, the thermal and electrical parameters and submodels used for the simulation are described. Thus, the calculation procedure that allows one to determine the chip's temperature is illustrated. In the latter part of the paper, some results related to a practical application for which the model has been used and the experimental validation of the model are presented.

A simple conversion formula for type 'T' (copper-constantan) thermocouple readings

A simple formula is given for the calculation of junction temperature from the measured EMF of a type 'T' (copper-constantan) thermocouple. The formula is accurate to better than 0.1 degrees over the range -200 degrees to +400 degrees C, and requires only eight arithmetic operations for its evaluation.

Modeling Second Breakdown in PN Junctions with NET-2

A diode model has been constructed which simulates second breakdown and which allows for the calculation of junction temperature as a function of time in the reverse region. The model was generated for the NET-2 circuit analysis code, and also includes avalanche breakdown. Second breakdown is assumed to begin at the critical temperature at which the resistivity is a maximum; at this point the junction area is caused to rapidly decrease, causing an increase in the temperature and the thermally generated leakage current. This results in the rapid voltage drop characteristic of second breakdown. With the addition of temperature calculations in the forward region and capacitive effects, it is anticipated that the model will be useful for predicting second breakdown for general inputs, and in general circuit configurations.