INFLUENCE OF FILLER MODIFICATIONS ON THE PERFORMANCE OF A NOVEL ANISOTROPIC CONDUCTIVE ADHESIVE UNDER TEMPERATURE/HUMIDITY AGING

摘要

The electronics industry, in recent years, has been focusing primarily on product miniaturization and lead-free assembly, through new component and PCB assembly technologies. In portable consumer products, space constraints make the system in package (SiP) approach quite attractive. The use of conventional packaging techniques in a SiP approach is quite complicated, and results in large parasitic inductances. While flip chip bonding is a solution, need for planarity, additional processing steps, and high temperature processing make flip chip 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 discuss the performance characteristics and research findings pertaining to a novel anisotropic conductive adhesive (ACA) for component packaging and lead-free PCB assembly. In this study, the novel ACA's performance under highly accelerated stress testing (HAST), temperature humidity, and thermal aging will be discussed in detail. The test data will show that by modifying the ACA filler particle size and filler particle coating, the reliability performance under temperature-humidity aging can be positively impacted. In addition, the data will also show that thermal aging actually improves the contact resistance performance. Furthermore, the contact resistance performance of the different adhesive formulations will also be corroborated with shear testing.