Mechanical Engineering:

Title:           Study on error factor in temperature measurement of resin printed circuit board by thermocouples and its reduction method
Authors:      Koichi Hirasawa, Yoshinori Aruga, Yasushi Ohhashi, Toshio Tomimura
Abstract:     Recently, as typified by the automotive electronic equipment, it is not uncommon for the electronic components to be used under higher temperature environment than 100ºC. Under these circumstances, the temperature control of electronic component becomes increasingly important to maintain the performance of the electronic devices for a long period of time. Small surface mount components such as the surface mount resistors cool themselves by making use of the printed circuit board (PCB) as a heatsink. For surface mount resistors, as a result of our study, it has been clarified that over 90% of the heat generated in the resistive element of a 6.3mm×3.1mm sized relatively large resistor, and nearly 99% of the heat for small sized 1.0mm×0.5mm resistors are dissipated via PCB. Therefore, in the scope of thermal management of small electronic components, the temperature control of PCB is extremely important. When measuring the surface temperature of the resin PCB with relatively low thermal conductance by thermocouple, it is known that the heat dissipation from the thermocouple reduces the temperature of the attached part and causes significant errors. Unfortunately, however, it is rare to be discussed quantitatively in an easy way for the electronic device designers can understand. In this study, the temperature drop of the measurement point is investigated from a viewpoint of the constriction thermal resistance, which is caused by the contraction of heat flow when drawing the heat from a minute area, and appropriate use of the heat spreader is proposed.

Keywords:   Thermal Management, Surface Mount Device, Electrical Resistor, Thermo Couple,
Concentration Thermal Resistance
Pages:           103-107

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