The Reliability of 30 μm pitch COG joints fabricated using Sn/Cu bumps and non-conductive adhesive

We developed a reliable and ultra-fine pitch chip on glass (COG) bonding technique using non-conductive adhesive (NCA). Sn was used as a bump material because it has a high plastic deformation capability and it is cheaper than an Au bump. Sn bumps were formed using photolithographic and electroplating and reflowed to form the half-dome shape. Reflowed Sn bumps were used to reduce the NCA trapping. COG bonding was performed between the reflowed Sn/Cu bumps on the SiO 2 /Si wafer and ITO/Au/Cu/Ti/ glass substrate at 150degC by using a thermo-compression bonder. The bonded specimens were subjected to reliability test.