Joining lead wires to thin platinum alloy films

摘要

Disclosed is a two-step process of joining a lead wire to a 2x10-6 m thick platinum alloy film which rests upon an equally thin alumina insulating layer which is adhered to a metal substrate. Typically the platinum alloy film forms part of a thermocouple for measuring the surface temperature of a gas turbine airfoil. In the first step the lead wire is deformed 30-60% at room temperature while the characteristic 106 ohm resistance of the alumina insulating layer is monitored for degradation. In the second step the cold pressed assembly is heated at 865 DEG -1025 DEG C. for 4-75 hr in air. During the heating step any degradation of insulating layer resistance may be reversed, provided the resistance was not decreased below 100 ohm in the cold pressing.