Abstract
Chip-on-film (COF) is a new technology after tape-automated-bonding (TAB) and chip-on-glass (COG) in the interconnection of liquid crystal module (LCM). The thickness of the film, which is more flexible than TAB, can be as thin as 44 μm. It has pre-test capability, while COG hasn't. It possesses great potential in many product fabrication applications. In this study, we used anisotropic conductive film (ACF) as the adhesive to bind the desired IC chip and polyimide (PI) film. The electric path was formed by connecting the bump on the IC and the electrode on the PI film via the conductive particles in the ACF. In the COF bonding process experimental-design-method was applied basing on the parameters, such as bonding temperature, bonding pressure and bonding time. After reliability tests of (1) 60 °C/95%RH/100 Hr and (2) -20 °C to approximately 70 °C/30 cycles, contact resistance was measured and used as the quality inspection parameter. Correlation between the contact resistance and the three parameters was established and optimal processing condition was obtained. The COF samples analyzed were fabricated accordingly. The contact resistance of the COF samples was measured at varying temperature using the 4 points test method. The result helped us to realize the relationship between the contact resistance and the operation temperature of the COF technology. This yielded important information for circuit design.