Proceedings of the 7th World Congress on Mechanical, Chemical, and Material Engineering (MCM'21)
Prague, Czech Republic Virtual Conference – August, 2021
Paper No. ICMIE 130
DOI: 10.11159/icmie21.130

Study of Temperature Fields and Heat Exchange Surfaces ofSemiconductor Component.
Peter Hrabovský1, Zuzana Kolková1, Jozef Matúšov1, Zlatica Skákalová1, Ľuboš Daniel1
1

Research Centre of University of Zilina
Univerzitná 8215/1, 010 26 Žilina, Slovakia
peter.hrabovsky@uniza.sk
Abstract – This article focuses on methods of cooling and dissipating thermal energy from electrical components installed in electricvehicles, control centres, information technology, space projects and others. The aim is to research the heat dissipation and the formationof temperature fields of a semiconductor power component installed in closed or tight spaces. The method of cooling the components isbased on the method of heat transfer and the cooling technology used. For the design of cooling, it is necessary to know the location andposition of the examined component, as well as the possibility of heat dissipation. This introductory part of the heat transfer theory defines
the already known methods of heat transfer, on the basis of which the design of the cooling capacity is defined.
Keywords: Heat transfer, conduction, convection, radiation, cooling, thermal imaging.

1. Introduction
Heat is generated when current flows through a resistor in an electrical circuit. A semiconductor device can be considered
as a type of resistor that generates heat when a current passes in proportion to the ON resistance (internal resistance whencurrent flows through the current).
Heat can adversely affect the semiconductor device itself as well as the electronic system that uses the device. Inparticular, it can seriously compromise security, performance, and reliability.
Excessive heat caused by poor heat dissipation design can result in smoke or ignition, as well as degraded equipment
performance, such as slowing its operating speed and, in the worst case, damage or malfunction. Although the worst casescenario can be avoided, reliability is adversely affected by equipment failure and shorter system life.
To prevent this adverse effect, thermal design is necessary for semiconductor packaging.

2. Ways of Heat Transfer
The theory of energy transfer forms the basis of calculations in the construction, design and operation of thermalequipment. It is a necessary prerequisite for a qualified solution to the tasks of optimizing heat and cold consumption in all
thermal engineering equipment.
Heat is propagated by conduction, flow, radiation and the transfer of matter (moisture). These forms of transmission
vary considerably, so they are governed by different laws.
According to kinetic theory, heat is the total kinetic energy of the disordered motion of the particles of which a substanceis composed. The conversion of mechanical work into heat is explained by kinetic theory as the conversion of the energy ofordered motion into the kinetic energy of disordered motion of particles.
Heat flows from a warmer body to a colder one. In fact, energy flows, which is converted into a disordered movementof the molecules of the substance (in the case of gases) or increases the oscillation of atoms in the crystal lattice (in the caseof solids) - thus increasing (or decreasing) its temperature. Heat is thus a measure of the energy that a warmer body transfers
to a colder body during heat exchange. When the body receives energy in the form of heat, its internal energy rises [1].
All transitions from one state (evaporation, solidification, melting, condensation, evaporation, sublimation anddesublimation) to another are associated with a change in internal energy. During the working cycle of the heat pipe, theliquid state of the working substance changes to gaseous in the evaporator by the action of heat. By flowing the gaseous statethrough the condensing part, precipitation occurs on the walls of the condenser, the gaseous state of the working substancechanges to liquid.

ICMIE 130-12.1. Heat Transfer by Conduction
Heat transfer by conduction is carried out by molecular energy transfer between substances or their particles thatcome into contact and have different temperatures; free electrons are involved in metal bodies. It depends quantitatively
on the physical and geometric shapes and dimensions of the heat-conducting substances and on the temperature
difference between their parts (or surfaces) [2].
The simplest case of heat conduction is a rod with a constant cross-section S and a length L, the ends of which havetemperatures T1 and T2. Heat of magnitude is then transferred between these two ends in time t:
ΔQ =λ. S. (T2 − T1)
ΔtL(1)

Where λ is thermal conductivity, Δ𝑄 heat transfer by conduction (W / m ). The thermal conductivity values fordifferent substances vary greatly. Metals usually have high thermal conductivity (for example copper 390 Wm−1K − 1,aluminum 240 Wm − 1K − 1, platinum 70 Wm − 1K − 1, steel 40 Wm − 1K − 1).
22.2. Heat Transfer by Convection
Heat transfer by convection takes place only in liquids (liquids and gases) by the effect of displacement and mixingof their unevenly heated particles, the more intense the higher the speed of movement. Because fluid particles withdifferent temperatures come into contact with it, it is then accompanied by heat conduction.
Simultaneous heat transfer through conduction and conduction involves convective heat transfer; it can be naturalor forced. Natural (free) convection occurs when a fluid is agitated by the effect of a difference in the density of its
particles, e.g. due to the difference in their temperature (when it is heated or cooled). Forced convection occurs whenthe motion is induced artificially (eg by a fan, pump, etc.) [3].
2.3. Heat Transfer by Natural Convection
Natural convection is a motion that results from the differences between the interaction of gravity and density withina fluid. These differences may result from a gradient in temperature, concentration, or fluid composition. This chapter
deals with the heat transfer associated with natural convection excited by a temperature gradient in a Newtonian fluid.
The heat transfer from each of the expanded surfaces (ribbing) shown in Fig. 1 has been analysed so far. Predicting
heat transfer requires a solution for complex three-dimensional motion, for which there are several analyses.
Experimental data were obtained using air only.
In many practical applications, where there is a significant drop in temperature between the base of the ribs andtheir apex, natural convection, heat flux and heat transfer are affected. Very little information is available on theconnection between the conductivity of the ribbing and the fluid flow, and so our attention is limited to isothermal
ribbing. Since the first approximation, the heat transfer coefficient for isothermal ribbing can be used for the case where
the ribbing is not isothermal because there is a weak dependence on the temperature difference [4].

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Fig. 1: Type of ribbing of heat exchange surfaces.

2.4. Heat Transfer By Radiation
Thermal radiation is the process by which the internal energy of bodies is propagated to the environment through theemission of thermal radiation from its surface (solid bodies) or from its volume (gaseous bodies). When thermal radiation
hits other bodies, it can be absorbed and converted into the internal energy of these bodies (increase in their temperature).
Radiation is the result of changes in the microstructure of bodies, in its electron, resp. ionic composition and,accordingly, electromagnetic waves are generated by which this energy propagates [5]. E.g. the oscillation of ionscorresponds to low wave frequencies, but changes in the electron composition are high. The radiation has both a wave and a
corpuscular character. The relationship between wave and corpuscular radiation is given by Planck, according to whichbodies radiate or absorb energy only in certain quantities, the energy of which is proportional to the frequency of the waves:𝑐𝑄 = ℎ. 𝑣 = ℎ(2)λWhere h = 6,626.10-34 (Js) is the Planck constant, v - frequency (1 / s), λ - wavelength (m), c = 2,999.108 (m/ s), speed of light in vacuum, Q - heat transmitted by radiation (J).
3. Aim of Experiment

The aim of a simple experiment was to measure an electric semiconductor power component that is used in active electricvehicle systems, information technology control centres, space projects. During the measurement of the component tax atdifferent supplied electrical power, the thermal changes of the component surface and the temperature fields were monitored.
The measurement was performed using thermal imaging equipment.
From the individual images (Fig. 2. – Fig. 6.) taken with the help of thermovision, it can be stated that with a short power
load of the semiconductor component, temperature fields were formed on the component in which heat transfer took placeby conduction. At higher power loads (Fig. 3. – Fig. 6.), it is possible to observe heat transfer from the component to thenon-flammable insulating pad.

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Fig. 2: Thermal analysis at the initiation of transistors in a semiconductor device.

Fig. 3: Thermal analysis of a semiconductor component at an electrical power of 20W.

Fig. 4: Thermal analysis of a semiconductor component at an electrical power of 35W.

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Fig. 5: Thermal analysis of a semiconductor component at an electrical power of 70W.

Fig. 6: Thermal analysis of a semiconductor component at an electrical power of 80W.

Fig. 7: Recording diagram of the behaviour of a semiconductor component at stabilization of electrical power.

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In Figure 7 it is possible to see the steady power consumption by means of a semiconductor component. Due to thehigh heat production, it is possible to state the low working efficiency of the device.

4. Conclusion
During the measurement of the semiconductor component, the temperature fields arising during the operating cycle
the power component were detected by means of a thermal imaging system. Based on the measurement, more detailed
analyzes of the heat exchange surfaces of the component will be performed, which will show us the efficient heat transfer
and a suitable topic for the design of the cooling system.

Acknowledgements"This publication was realized with support of Operational Program Integrated Infrastructure 2014 - 2020 of theproject: Innovative Solutions for Propulsion, Power and Safety Components of Transport Vehicles, code ITMS
313011V334, co-financed by the European Regional Development Fund" and this work was supported by Grant Systemof University of Zilina No. 8021. 1/2020.

References[1] G. D. RAITHBY a kol., 1985. Natural convection. Handbook of heat transfer fundamentals, 2, 1-6.
[2] D REAY, Heat Pipes: Theory, Design and Applications. 5. Butterworth-Heinemann, 2006. 384 s. ISBN-13: 978-0-7566754-8, ISBN-10: 0-7506-6754-0, 2006
[3] F. J. STENGER, „Experimental Feasibility Study of Water-Filled Capillary-Pumped Heat Transfer Loops,“ NASA TMX-1310, 1966
[4] L. TREFETHEN, „On the Surface Tension Pumping of Liquids or a Possible Role of the Candlewick in Space
Exploration“ G.E. Tech. Info., Serial No. 615 D114, 1962
[5] D. WOLF, „Investigation of Temperature Control Characteristics of Loop Heat Pipe,“ 24th International Conference on
Environmental Systems, Society of Automotive Engineers, Friedrichshafen, Germany (SAE Paper No. 941576), 1944

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