At Fraunhofer Institute for Reliability and Microintegration IZM, Fiber Bragg Gratings (FBG) are used for online measurement of mechanical deformations and temperature changes within electronic packaging and mechatronic systems. 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). This paper discusses the effects that occur when the geometrical and mechanical properties of the measured object are comparable to the sensing system and when the fiber optic sensor is significantly influencing the measurement. 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 real-time cure monitoring during
production processes and ending with structural health monitoring during product lifetime and quality testing.