Evaluating the optimal location for embedded accelerometers using experimentally validated computer algorithms

With sensors and sensor circuits becoming increasingly smaller there is the possibility of embedding such systems within products to monitor their handling and operation during the whole life cycle. The manufacturing stage of the life cycle is seen as an important stage to monitor as the defects during operation can often be attributed to manufacturing faults. The assembly of high value printed circuit boards has been identified as a process that could benefit from such sensor circuits. Vibration sensors on the boards could detect many scenarios during manufacturing, such as shock loadings and number of times a board is manually handled. In addition to this, vibrations excited in the board are known to cause cracks in solder joints [1] and also thought to cause defects during the manufacture process, although this has yet to be fully quantified. The position of the accelerometer on the board is not greatly important in detecting shock loadings and whole body motion, however, when measuring vibration of the board the position of the accelerometer greatly influences the measured amplitude depending on the relative distance to nodal lines. This paper presents experimental and theoretical methods to identify the most appropriate location for an accelerometer to be positioned.