Reliability and failure mode of chip-on-film with non-conductive adhesive

COF (chip-on-film) is a new technology after TAB (tape-automated-bonding) and (COG) chip-on-glass in the interconnection of LCD drive ICs. The thickness of the film is more flexible than TAB, and can be as thin as 50 μm. Currently, the lead pitch of the film substrate can reach 30 μm and this is difficult for TAB. It has pre-test capability, while COG does not have. It possesses great potential in many product-fabrication applications. There are many kinds of COF interconnection technology, such as eutectic bonding, non-conductive-adhesive (NCA) joining and anisotropic-conductive-film (ACF) joining etc. The NCA interconnection technology for COF can meet the needs of fine pitch for higher-resolution LCD panel applications. The quality of COF with NCA was controlled by materials and parameter optimization, and experiments were carried out to understand the quality of the NCA process. In this paper, several issues of the NCA process for COF were discussed, include joint characteristics, reliability, and failure mode analysis. A silica filler is added to the NCA to adjust the basic characteristics such as CTE and Young\´s modulus. The reliability includes aging and peeling tests which were carried out to evaluate the joint quality of the "COF with NCA" process. And then failure mode analysis, including SAT and cross-sectioning, were undertaken to evaluate the process parameters and NCA characteristics.