Via-less two-metal tape-automated bonding system

Abstract

A Via-Less Two-Metal Tape-Automated Bonding System [100] for providing an interface to a device having a plurality of closely spaced leads is disclosed. The preferred embodiment of the invention comprises a dielectric film [102]that bears a pattern of conductive signal traces [104] on one side [102b] of the film [102] that match the leads of an integrated circuit that is fastened to the center of the rectangular TAB frame. The side [102a] of the film which is opposite from the side [102b] bearing the signal traces [104] has a ground plane [105] attached to it that controls the impedance characteristics of the conductive elements of the TAB frame. In previous TAB designs, the ground plane [105] is connected to the chip through a ground lead [106] that is coupled to the ground plane by a via that passes through the dielectic film in a direction that is perpendicular to the two planar axes of the film. In contrast, the present invention utilizes a ground lead [106] that is formed on the same side of the dielectric film [102] which holds the ground plane [105]. An inclined segment of the ground lead [106] then runs from the edge of the ground plane [105], down and over the thickness dimension of the dielectric layer [102], and then occupies the same plane as the signal leads [104] that emanate from the signal trace or circuit side [102b] of the dielectric layer [102]. In this common plane below the ground plane [105], both signal leads [104] and ground leads [106] extend toward the chip in a generally parallel arrangement.