Stressmessung auf Chip-Ebene - Ein Fahrtenschreiber für die Elektronikverarbeitung

This article investigates stress measurement within electronic systems during fabrication and reliability testing. Results of an on-chip MOS stress measurement technology are investigated with a special focus on soldering and encapsulation of systems. Experimental results are compared with numerical simulations. The stress sensor is based on a MOS chip, subdivided into 60 measurement cells (300 fim grid) and needs only four electrical connections. We are able to measure the shear and both main stresses in-plane of the chip surface. The stress value of the measurement cell can be interrogated subsequently within 50 ms time steps. The main potential of this stress measurement chip is to replace selected electronic parts and to investigate all production and lifetime related loads acting on the system. The presented measurement technique enables a more accurate characterization of manufacturing processes and polymer behavior. Finally the sensor enables the choice of optimized materials minimizing production related stresses and leading to more reliable products.