A number of different techniques exist for providing electrical connection between a semiconductor chip or package and a circuit board or other substrate. The current trend in many of these techniques is the use of solder bumps to form electrical connections instead of wire bonding. For example, bumps are used in such techniques as tape carrier package (TCP), chip on film (COF), and chip on glass (COG). Often techniques such as TCP and COF are more broadly referred to as tape automated bonding (TAB).
While bumps provide an advantage over wire bonding by allowing for a reduction in the spacing between the solder bumps as compared to the spacing between wire bonds, even bump techniques face potential limitations on the spacing between the bumps. For example, in the COG technique, a semiconductor chip (e.g., a liquid crystal display (LCD) driver integrated circuit (IC) package) may be bonded directly to the LCD substrate. In this technique, ACF (anisotropic conductive film) tape is disposed between pads of the LCD substrate and the associated bumps on the driver IC package to form the electrical connection. ACF tape contains electrically conductive particles that are embedded in an insulating material. The conductive particles provide electrical connection between the solder bumps and the pads on the LCD substrate. As the gap between bumps, however, becomes smaller, the particles in the ACF tape may provide electrical connection between bumps; thus, causing a short circuit.
USPTO Backgrounds
USPTO Backgrounds