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Surface Temperature Measurements: Influence of the Thermocouple
2023.06.21
Points of this article
・When measuring the surface temperature of a semiconductor component, the smaller the package of the component, the greater is the influence of heat dissipation from the thermocouple, so caution must be exercised.
It has been stated where relevant that, in measurements of the surface temperature of a package, heat dissipation from the thermocouple must be held to a minimum. In this article, experimental results are presented as examples of the actual extent of this effect.
Influence of the Thermocouple
The table below presents the results of determining the thermal resistance θJA by performing temperature measurements, using an 0.1 mm dia. type K thermocouple and an 0.3 mm type T thermocouple, of semiconductor components in two types of packages–an extremely small 0.8×1.6×0.6t mm package, and a 6.5×9.5×2.5t mm package. Two types of PCBs were used, having one layer and four layers.
When comparing the diameters of thermocouples used in measurements, because thermocouples with thicker wires have lower thermal resistance, that is, heat dissipation is greater for thicker wires, consequently measurements are performed with lower thermal resistance.
Further, we see that this tendency is more prominent for smaller packages, for which the influence of the thermocouple is greater. Hence when a package for measurement is small, special attention must be paid, and it is extremely important that measures be taken to minimize the effect of heat dissipation from the thermocouple.
*PCB is a JEDEC standard size, 114.2×76.3×1.6t （mm）
【Download Documents】 Thermal Design of Semiconductor Components in Electronics
Thermal design has become a new issue in the design of electronic equipment in recent years, as thermal countermeasures have been the focus of attention. Although heat has been an important consideration for some time, the requirements for electronic equipment have changed in recent years, making it necessary to review conventional thermal countermeasures. This handbook describes thermal design based on the assumption that ICs and transistors are basically used in electronic equipment.
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Basic Alternating Current (AC)
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- Thermal Resistance Data: θJA and ΨJT in Estimation of TJ: Part 2
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- Surface Temperature Measurements: Influence of the Thermocouple
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