Structural health monitoring by embedded fiber Bragg gratings: Fiber Optic Strain and Temperature Sensors for Quality Measurement within Microelectronics

摘要

The usage of Fiber Bragg Gratings (FBG) as strain sensors is quite common for measurement objects with geometrical dimensions high above the one of the fiber. At Fraunhofer Institute for Reliability and Microintegration IZM we are exploring FBG for online measurement of mechanical deformations and temperature changes within electronic packaging and mechatronic systems. Especially encapsulation processes with rapid prototyping materials like stereolithography resin and vacuum casting polymers are monitored, as well as high volume production processes like Reactive Injection Molding (RIM). Package reliability in electronics is intensively studied at our institute and this paper will evaluate the ability of FBG to detect structural changes like cracks and delaminations within electronics. By embedding the fibers directly into the polymer packaging the sensor can be used for continuous lifetime monitoring of the system, starting with realtime cure monitoring during production processes and ending with structural health monitoring during product lifetime and quality testing.