Adhesives in micromechanical sensor packaging: Dissertation

This thesis deals with electronics packaging and its contents can be divided into two parts. The first presents knowledge for selection, use and reliability assessment of isotropically conductive adhesives (ICAs) in die and flip chip bonding. The thesis also proposes a lifetime model of ICA flip chip bonds in thermal cycling. The lifetime of ICA bonds appears to be influenced less by non-recoverable strain than the lifetime of solder bonds. Thus ICAs may outlive solder in applications of cyclic operation, such as under-hood automotive electronics. In the second part this knowledge is utilised in micro electro mechanical system (MEMS) sensor packaging. The applications include a microphone, a differential pressure sensor and a miniaturised IR spectrometer. The effect of packaging on the microphone and the pressure sensor performance has also been evaluated by measurements. The results showed that the effect of packaging was negligible and that these devices can be used in a wide temperature range, e.g. between -40°C and 60°C.