A flexible temperature sensor plays an important role in some modern engineering applications such as temperature measurements of curved surfaces or interlayer structures with narrow gaps in industry equipment (e.g. iron cores of generator, motor and transformer).
Platinum is generally used for metallic film temperature sensors owing to its high accuracy and stability, but it is expensive. Several kinds of metallic materials like copper are also occasionally used for special temperature measurement and other temperature measurements that involve not so high accuracy.
Recently, copper film temperature sensors are widely utilized for measurement of temperature in industry instead of platinum sensors because the design of the former based on PCB technology allows cost-efficient fabrication, easy handling, and simple retrofitting and replacement. But, the defects existing on PCB leads lower its performance and stability.
The lethal defects can be divided into two types; one is disconnection and the other is fall. Disconnection leads to reduction in fabrication yield of sensors and fall results in decrease in their stability and lifetime. Therefore, it is important to avoid the defects on PCB leads.
Pak Son Guk, a section head at the Semiconductor Institute, has proposed a new layout design of a sensor to avoid the defects.
The new layout design with addition of detour leads guarantees the yield of almost 98%. The sensor was tested for a long time of 3 000 hours at 150℃. The deviation rate of resistance of the sensor is less than 0.1%, TCR 4.1×10-3℃-1 and the maximum current 10mA.
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