Novel anisotropic conductive adhesive for 3D stacking and lead-free PCB packaging — A review

In recent years, the electronics industry has been focused on product miniaturization and RoHS compliance, through new component and PCB assembly technologies. In portable consumer products, while chip stacking via the system in package (SiP) approach is becoming quite popular, the use of conventional packaging techniques is complicated, and results in large parasitic inductances. The need for planarity, additional processing steps, and high temperature processing, make bumping and flip chip bonding a less than ideal solution. These challenges and the need to eliminate lead-based solders and halogen containing substrate materials have renewed the industry's interest in exploring newer assembly methods at both the component packaging and lead-free PCB assembly levels, especially by using conductive adhesives. Conductive adhesives can be typically processed at a relatively low temperature which is important for thermally sensitive components. This paper will provide a summary of the research using a novel ZTACH™ anisotropic conductive adhesive (ACA) for component level and lead free Printed Circuit Board (PCB) level packaging.