Moisture effects on adhesion of non‐conductive adhesive attachments

Abstract

PurposePersonal and portable electronic devices are becoming an important part of the everyday lives. Electronics miniaturization has been and continues to be the most important driver in this development. The current level of miniaturization has made the use of solder joints challenging and new methods, such as adhesive attachments, have been developed. The applicability of these methods depends crucially on their long‐term reliability. Typical failures mechanisms in adhesive connection include cracking, open joints and delamination. Moisture is the principal cause of failures in adhesive attachments. The purpose of this paper is to examine the long‐term effects of moisture and extended temperature on non‐conductive adhesive (NCA) attachments.Design/methodology/approachMoisture and extended temperature on NCA attachments are examined by strength tests and by finite element models.FindingsThe increase in temperature and moisture induces stresses on the interface of the adhesive and the chip. In the experiments, it is found that the adhesion strength of the adhesive decreased as a function of the time for which the samples are in a humid environment. Failures due to delamination are seen to be the result of these two mechanisms.Originality/valueReduction of pitch causes manufacturing problems in direct solder attachments. This paper examines a promising technique to overcome this problem by using adhesive attachment. Instead of solder joints in flip chip attachment, the chips can be attached to the substrate, or components can be attached to a printed wiring board, with adhesives.