Platinum temperature sensor

摘要

A platinum temperature sensor includes a meandering pattern portion and outlet portions continuously connected to respective ends thereof which are defined by a platinum film which is formed on an insulating substrate. External electrodes are formed to cover the outlet portions as well as the ends of the insulating substrate provided with the outlet portions. Each of the external electrodes comprises a first layer containing platinum or nickel which is in contact with the outlet portion and with the insulating substrate, a second layer containing silver and platinum which is formed on the first layer, a third layer containing nickel which is formed on the second layer, and a fourth layer containing tin or solder which is formed on the third layer. The first layer suppresses diffusion of silver contained in the second layer, and the third layer improves heat resistance of the second layer, while the fourth layer improves solderability.