Comparison of QFN chips glued by ACA and NCA adhesives on the flexible substrate

Abstract

The paper deals with the QFN components assembly to the PET substrate with silver conductive pattern by anisotropically conductive adhesive (ACA) or non-conductive adhesive (NCA) with UV curing. Motivation for the experiment was to investigate and compare conductive joints prepared by ACA and NCA and make comparison of their reliability during the accelerated climatic ageing. For the NCA adhesive, the electrical conductivity was achieved by mechanical contact of the QFN component pads and substrate pattern pads. Therefore, the downforce on the QFN chip during the UV curing was important just as the adhesive´s shrinkage rate. The assembly of the QFN components by non-conductive adhesive had similar or better properties in comparison with anisotropically conductive adhesive (ACA) joints and therefore non-conductive adhesives could be recommended for some special applications.