Moisture effects on reliability of non-conductive adhesive attachments

Miniaturisation of electronic devices and the RoHS directive have made the use of solder joints challenging. Thus, new methods for attachment of chips have been developed, such as adhesive attachments. Moisture is the principal cause for failures in these attachments. The effects of moisture to non-conductive adhesive attachments were studied by modeling with finite element method and by environmental test. It was found that the structure was more reliable than what was predicted based on the models. The failure mode was seen to be the junction opening, while the principal cause for failures was shown to be long-term relaxation of the adhesive. The junctions on the edges of the chip were the primary locations for failure.