Conductive Adhesive Films (ACFs and NCFs) Materials For Electronics Packaging Applications

Due to the increasing demand for higher performance, greater flexibility, smaller size, and lighter weight in mobile and wearable electronic products, there have been growing needs of various electronic packaging products and fine-pitch interconnection technologies. To realize various state-of-art mobile and wearable electronic products, fine pitch and flexible packaging & interconnection technologies are needed. As one of the promising fine pitch and flexible packaging and interconnection technologies, conductive adhesive films materials such as ACFs(Anisotropic Conductive Films) and NCFs(Non Conductive Films) are widely used now. In general, ACFs have two technical limitations such as (1) ultra-fine pitch shortage free interconnection and (2) higher current handling capability. For (1) ultra-fine pitch applications without electrical shortage, new concept of Nano-fiber ACFs and APL(Anchoring Polymer Layer) ACFs have been successfully invented by KAIST both for less than 20 micron pitch COG(Chip On Glass), COP(Chip On Polymer). and COF(Chip On Flex). And they can be also used for less than 50 micron pitch FOF(Flex On Flex) and FOB(Flex On Board) applications. In addition, for (2) higher current handling capability applications, new solder ACFs have been also introduced by KAIST to replace the conventional metal particles based ACFs interconnection. By solder ACFs, 30% low contact resistance, 4 X higher current handling capability, and excellent reliability were successfully achieved compared with conventional ACFs. Furthermore, ACFs materials-based packaging and interconnection method can provide the flexible interconnect solution for OLED(Organic LED) COP and COF/CIF(Chip In Flex) packages to realize wearable electronic products.Recently the 3-D die chip stacking using the Through silicon via (TSV) technology has been widely used for stacking memory and ASIC chips. In the 3D-TSV vertical interconnection, Cu pillar/Sn-Ag eutectic solder bump is one of the promising bonding method. After the 3D-TSV chips are interconnected with the bumps, the gap between stacked chips should be filled with underfill materials. However, capillary flow underfill between 3D-TSV stacked chips become difficult because of increased chip/wafer area, decreased gap height, and multiple chip/wafer stacking. Therefore, new bonding method using NCFs materials, which performs both Cu-pillar/Sn-Ag flip chip bump to metal pads interconnection and underfils at the same time has been extensively used.In this presentation, the ACFs materials for ultra-fine pitch and higher current carrying interconnection and the NCFs for 3D-TSV chip stacking applications will be introduced.