A Method of Calculating the Errors of Measurements of the Temperatures of Radio-Electrical Components of a Printed Circuit

Abstract

The problem of measuring the temperatures of the radio-electrical components of printed circuits is investigated. A temperature measuring sensor (thermocouple) and possible errors are considered. A systematic error compensation method is proposed to ensure the necessary accuracy of measurements made with the temperature sensor.Temperature is one of the main destabilizing factors acting on radio-electronic apparatus both in the on and off states. Radio-electronic apparatus usually consists of units containing several printed circuits. In turn, each printed circuit contains tens or hundreds of electrical or radio components -resistors, capacitors, diodes, transistors, integrated microcircuits etc. Any component has a working temperature range, determined under technical conditions. If the temperature modes of operation are not satisfi ed, there will be a deterioration in the characteristics, and the electrical and radio components themselves, and even the whole apparatus, may break down.To guarantee the correct temperature modes of operation of radio-electronic apparatus, designers use computer-aided design (CAD) systems to model the processes occurring in the apparatus, taking into account thermal and mechanical actions. Several software packages are available in the market. A fragment of this kind of CAD system available in the Russian market is the ASONIKA system. This system was developed and tested by staff at the ASONIKA Research Institute and at the Department of Radioelectronics and Telecommunications at the Higher School of Economics (NIU VShE). Examples of its use are described in [1,2].At the stage when radio-electronic apparatus is being tested, the problem arises of measuring the temperatures of radio-electrical components by contactless and contact methods. Instruments which enable contactless measurements of temperature to be carried out are pyrometers and thermal imaging devices, which are particularly effective and provide a complete temperature map of the printed circuit system for the whole unit in a clear form on a colored display. Some models enable the results obtained to be stored in external memories for transfer and a detailed investigation on a personal computer.However, the use of the above instruments does not enable the temperature of radio-electrical components, situated inside the unit, to be measured. In such cases it is better to use a contact method of measurement, for example, using a thermocouple [3,4]. A thermocouple has a number of drawbacks: the need to make an accurate measurement of the temperature of the free end and to compensate for it, the occurrence of corrosion and chemical processes in the metals or alloys, and, in

Basis of the necessity of the thermal modelling and analysis of its problem

“…According to articles [3,4,6] the most fruitful and promising methods of identification are using custom models. The method reduces to the scheme, it is shown in figure 4.…”