ESTIMATION OF THERMAL PARAMETERS OF POWER BIPOLAR TRANSISTORS BY THE METHOD OF THERMAL RELAXATION DIFFERENTIAL SPECTROMETRY

Thermal performance of electronic devices determines the stability and reliability of the equipment. This leads to the need for a detailed thermal analysis of semiconductor devices. The goal of the work is evaluation of thermal parameters of high-power bipolar transistors in plastic packages TO-252 and TO-126 by a method of thermal relaxation differential spectrometry. Thermal constants of device elements and distribution structure of thermal resistance defined as discrete and continuous spectra using previously developed relaxation impedance spectrometer. Continuous spectrum, based on higher-order derivatives of the dynamic thermal impedance, follows the model of Foster, and discrete to model of Cauer. The structure of sample thermal resistance is presented in the form of siх-chain electro-thermal RC model. Analysis of the heat flow spreading in the studied structures is carried out on the basis of the concept of thermal diffusivity. For transistor structures the area and distribution of the heat flow cross-section are determined. On the basis of the measurements the thermal parameters of high-power bipolar transistors is evaluated, in particular, the structure of their thermal resistance. For all of the measured samples is obtained that the thermal resistance of the layer planting crystal makes a defining contribution to the internal thermal resistance of transistors. In the transition layer at the border of semiconductor-solder the thermal resistance increases due to changes in the mechanism of heat transfer. Defects in this area in the form of delamination of solder, voids and cracks lead to additional growth of thermal resistance caused by the reduction of the active square of the transition layer. Method of thermal relaxation differential spectrometry allows effectively control the distribution of heat flow in high-power semiconductor devices, which is important for improving the design, improve the quality of landing crystals of power electronics products to reduce overheating

ОЦЕНКА ТЕПЛОВЫХ ПАРАМЕТРОВ МОЩНЫХ БИПОЛЯРНЫХ ТРАНЗИСТОРОВ МЕТОДОМ ТЕПЛОВОЙ РЕЛАКСАЦИОННОЙ ДИФФЕРЕНЦИАЛЬНОЙ СПЕКТРОМЕТРИИ

Thermal performance of electronic devices determines the stability and reliability of the equipment. This leads to the need for a detailed thermal analysis of semiconductor devices. The goal of the work is evaluation of thermal parameters of high-power bipolar transistors in plastic packages TO-252 and TO-126 by a method of thermal relaxation differential spectrometry. Thermal constants of device elements and distribution structure of thermal resistance defined as discrete and continuous spectra using previously developed relaxation impedance spectrometer. Continuous spectrum, based on higher-order derivatives of the dynamic thermal impedance, follows the model of Foster, and discrete to model of Cauer. The structure of sample thermal resistance is presented in the form of siх-chain electro-thermal RC model. Analysis of the heat flow spreading in the studied structures is carried out on the basis of the concept of thermal diffusivity. For transistor structures the area and distribution of the heat flow cross-section are determined. On the basis of the measurements the thermal parameters of high-power bipolar transistors is evaluated, in particular, the structure of their thermal resistance. For all of the measured samples is obtained that the thermal resistance of the layer planting crystal makes a defining contribution to the internal thermal resistance of transistors. In the transition layer at the border of semiconductor-solder the thermal resistance increases due to changes in the mechanism of heat transfer. Defects in this area in the form of delamination of solder, voids and cracks lead to additional growth of thermal resistance caused by the reduction of the active square of the transition layer. Method of thermal relaxation differential spectrometry allows effectively control the distribution of heat flow in high-power semiconductor devices, which is important for improving the design, improve the quality of landing crystals of power electronics products to reduce overheating. Температурный режим работы электронной аппаратуры определяет надежность и стабильность оборудования. Это приводит к необходимости детального теплового анализа полупроводниковых приборов. Цель работы – оценка тепловых параметров мощных биполярных транзисторов в пластмассовых корпусах TO-252 и TO-126 методом тепловой релаксационной дифференциальной спектрометрии. Тепловые постоянные элементов приборов и распределение структуры теплового сопротивления определены в виде дискретного и непрерывного спектров с использованием ранее разработанного релаксационного импеданс-спектрометра. Непрерывный спектр рассчитан на основе производных высшего порядка динамического теплового импеданса и соответствует модели Фостера, дискретный – модели Кауера. Структура теплового сопротивления образцов представлялась в виде шестизвенной электротепловой RC-модели. Анализ растекания теплового потока в исследуемых структурах проводился на основе концепции температуропроводности. Для транзисторных структур определены площадь и распределение сечения теплового потока. На основе проведенных измерений оценены тепловые параметры мощных биполярных транзисторов, в частности, структура их теплового сопротивления. Для всех измеренных образцов выявлено, что тепловое сопротивление слоя посадки кристалла вносит определяющий вклад во внутреннее тепловое сопротивление транзисторов. В переходном слое на границе полупроводник– припой тепловое сопротивление возрастает из-за изменения механизма теплопереноса. Наличие дефектов в этой области в виде отслоений припоя, пустот и трещин приводит к дополнительному росту теплового сопротивления в результате уменьшения активной площади переходного слоя. Метод тепловой релаксационной дифференциальной спектрометрии позволяет эффективно контролировать распределение тепловых потоков в мощных полупроводниковых приборах, что необходимо для совершенствования конструкции, повышения качества посадки кристаллов изделий силовой электроники с целью снижения их перегрева.

ДИАГНОСТИКА ТЕХНОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК МОЩНЫХ ТРАНЗИСТОРОВ С ПОМОЩЬЮ РЕЛАКСАЦИОННОГО ИМПЕДАНС–СПЕКТРОМЕТРА ТЕПЛОВЫХ ПРОЦЕССОВ

The efficient method of determining thermal parameters in high-power field-effect transistors has been developed and tested based on a study of transient processes during self heating by direct current. With the developed relaxation spectrometer of thermal processes differential distribution profiles of thermal resistance of KP723G transistors have been investigated which were selected in accordance with the regimes of setting of their crystals. Thermal resistance spectra have been obtained from the analysis of time−dependent dynamic thermal impedance using a new non−destructive method of differential spectroscopy using higher order derivatives (order 3). We present both continuous (integral) and discrete spectra of the distribution of internal thermal resistance in the transistors and the value of the junction/case thermal resistance. Thermal characteristics of the KP723G transistors and their imported counterparts IRLZ44 and IRLB3036 have been determined. The method of determining the active area of devices has been developed and its decrease during heating has been shown. The proposed methodology is useful in solving technological problems of forming the setting layers of crystals and intermediate layers between a crystal and a heat sink and also for the development of thermal models in SPICE modeling of powerful MOSFETs and diode emitters.На основе исследования переходных процессов при саморазогреве прямым током разработан и апробирован эффективный метод определения тепловых параметров мощных полевых транзисторов. С помощью разработанного релаксационного спектрометра тепловых процессов исследованы дифференциальные профили распределения теплового сопротивления транзисторов КП723Г, подобранных в партии в соответствии с режимами посадки их кристаллов на теплоотводящее основание. Спектры тепловых сопротивлений рассчитаны из анализа временной зависимости динамического теплового импеданса новым неразрушающим методом дифференциальной спектроскопии с использованием производных высших порядков (3-го порядка). Представлены как непрерывные (интегральные), так и дискретные спектры распределения внутреннего теплового сопротивления транзисторов, а также значения теплового сопротивления переход—корпус. Определены тепловые характеристики транзисторов КП723Г и их импортных аналогов IRLZ44 и IRLB3036. Развит метод оценки активной площади приборов и установлено ее уменьшение с нагревом. Показано, что предложенные методики полезны при решении технологических проблем формирования слоев посадки кристаллов и создания промежуточных слоев между кристаллом и теплоотводящим основанием, а также для разработки тепловых моделей при SPICE-моделировании мощных полевых транзисторов и диодных излучателей

Automatic Mapping of Discontinuity Persistence on Rock Masses Using 3D Point Clouds

Finding new ways to quantify discontinuity persistence values in rock masses in an automatic or semi-automatic manner is a considerable challenge, as an alternative to the use of traditional methods based on measuring patches or traces with tapes. Remote sensing techniques potentially provide new ways of analysing visible data from the rock mass. This work presents a methodology for the automatic mapping of discontinuity persistence on rock masses, using 3D point clouds. The method proposed herein starts by clustering points that belong to patches of a given discontinuity. Coplanar clusters are then merged into a single group of points. Persistence is measured in the directions of the dip and strike for each coplanar set of points, resulting in the extraction of the length of the maximum chord and the area of the convex hull. The proposed approach is implemented in a graphic interface with open source software. Three case studies are utilized to illustrate the methodology: (1) small-scale laboratory setup consisting of a regular distribution of cubes with similar dimensions, (2) more complex geometry consisting of a real rock mass surface in an excavated cavern and (3) slope with persistent sub-vertical discontinuities. Results presented good agreement with field measurements, validating the methodology. Complexities and difficulties related to the method (e.g. natural discontinuity waviness) are reported and discussed. An assessment on the applicability of the method to the 3D point cloud is also presented. Utilization of remote sensing data for a more objective characterization of the persistence of planar discontinuities affecting rock masses is highlighted herein

Measurement and analysis of thermal parameters and efficiency of laser heterostructures and light-emitting diodes

A thermal resistance characterization of semiconductor quantum-well heterolasers in the AlGaInAs–AlGaAs system (λst ≈ 0.8 µm), GaSb-based laser diodes (λst≈2µm), and power GaN light-emitting diodes (visible spectral region) was performed. The characterization consists in investigations of transient electrical processes in the diode sources under heating by direct current. The time dependence of the heating temperature of the active region of a source ∆T(t), calculated from direct bias change, is analyzed using a thermal RTCT equivalent circuit (the Foster and Cauer models), where RT is the thermal resistance and CT is the heat capacity of the source elements and external heat sink. By the developed method, thermal resistances of internal elements of the heterolasers and light-emitting diodes are determined. The dominant contribution of a die attach layer to the internal thermal resistance of both heterolaser sources and light-emitting diodes is observed. Based on the performed thermal characterization, the dependence of the optical power efficiency on current for the laser diodes is determined. Keywords: heterostructure, light-emitting diode, thermal resistance, efficiency

Comparative Analysis of the Thermal Resistance Profiles of Power Light-Emitting Diodes Cree and Rebel Types

Analysis of the thermal resistance of power light-emitting diodes (LEDs) of Cree and Rebel types is developed. Components of the thermal resistance of the diodes are determined and several distinguishes between different methods are obtained. Behavior of bottleneck effect related to definite interfaces is established. The value of LED active junction area is evaluated too