KOA’s flatchip resistors series WK73 with wide terminations are especially suited for power applications. The thick film resistors have rated power from 1 to 1.5 Watts and by the inverse form geometry of their soldering pads, offer very reliable operation even in load and temperature cycling environments.
Typical applications of these 155 °C rated products include ECUs, power supplies, and industrial automation equipment. The 1020 and 1218 sized resistors are rated 1 Watt, and the 1225 sized resistor rated 1.5 Watts at 70 °C ambient temperature, respectively. Ohmic range for the products with 5 % tolerance extends from 10 mOhms to 1 MOhms while the 1 % tolerance products start at 22 mOhm and end at 1 MOhms. The temperature coefficient of resistance depends on the ohmic value and varies between +/- 100 and +/- 800 ppm/K.
A special feature of these resistors is the inverse form of their pad layout, i.e. the terminations are placed at the wide sides of the resistor´s base area. This special construction of the solder pads minimizes the mechanical stress on the solder joints during load or temperature cycling operation mode. On top of that, the relatively large pad areas ensure excellent heat transport from the resistive element to the PCB. Depending on chip size, up to 150 % of the rated power of a standard flat chip resistor can be dissipated by these new flatchip resistors. At identical power ratings, these resistors exhibit less self-heating than conventional form resistors, thus increasing the reliability of the component.
electronica, booth B6.313
EPP Europe 441
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