Failure mechanism of anisotropic conductive adhesive interconnections in flip chip ICs on flexible substrates

In this work we study how the endurance performance of electrically conductive adhesive interconnections of flip chip integrated circuits with a pitch of 200 and 150/spl mu/m on flexible substrates is affected by varying environmental conditions. This is accomplished by comparison of offline and online control measurements that are carried out to monitor the electrical resistance in temperature-humidity and temperature cycling stress tests. From the gradual degradation of the resistance with time and the failure analysis, it is conjectured that periodic absorption and desorption of moisture forms one of the more important failure mechanisms in this type of assembly.