Fabrication and Application of Micro Sensor Arrays on Nickel Substrate for Meso-Scale Manufacturing Processes

Real time monitoring, diagnosis and control of numerous manufacturing processes is of critical importance in reducing operation costs, improving product quality, and shortening response time. Current sensors used in manufacturing, especially at meso/micro scale, are normally unable to provide measurements with desired spatial and temporal resolution at critical locations in metal structures (e.g. tooling). Micro sensors are expected to offer tremendous benefits for real time sensing in manufacturing processes. In this study, a batch production of micro thin film sensor arrays was realized by transferring thin film sensors from silicon wafers directly onto nickel substrates through standard microfabrication and electroplating techniques. To demonstrate the potential applications, micro sensor arrays that consist of multiple thermocouples and thermopiles were designed, fabricated and transferred into electroplated nickel to study temperature field and heat generation during meso-scale ultrasonic welding. Sensor arrays are arranged immediately adjacent to the mesoscale welding area for in-situ temperature and surface heat flux measurement. These micro sensor arrays provide high spatial and temporal resolution that cannot be achieved with conventional macro sensors.