COG Terminal Structure Reducing Short-Circuit Probability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In liquid crystal display devices, the reduction in terminal pitch leads to a decrease in spacing between terminals, increasing the probability of short-circuiting between terminals and IC driver bumps, which existing solutions fail to adequately address.
Innovation Solution
The implementation of a terminal structure featuring a first ITO formed within a through-hole in an insulation film, with a second ITO formed over the first ITO but not extending outside the through-hole, and the second ITO being made polycrystalline to ensure it only contacts the first ITO, thereby reducing the width of the uppermost-layer ITO and preventing short-circuiting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the terminal pitch is reduced to decrease IC driver chip size, then the chip size is reduced and cost is lowered, but the spacing between terminals is narrowed and short-circuiting becomes a problem
Solution Approach 1:
The terminal structure is segmented into multiple functional layers: a recess portion in the insulating film, a lower-layer conductive film filling the recess, and an upper-layer conductive film covering the lower-layer film. This segmentation allows each layer to perform its specific function - the recess and lower-layer film provide bump entry guidance and connection, while the upper-layer film provides insulation, enabling reduced terminal pitch without short-circuiting.
Solution Approach 2:
The terminal structure transitions from a planar two-dimensional layout to a three-dimensional vertical structure by forming a recess portion that extends downward from the insulating film surface. This vertical dimension allows the conductive films to be stacked, separating the bump connection function from the insulation function in the vertical direction, thereby maintaining insulation even when horizontal spacing is reduced.
2Ease of operation
If the opening of the recess is enlarged to facilitate bump entry, then bumps can easily enter the recess, but the width of the upper-layer conductive film is enlarged and spacing between terminals is narrowed
Solution Approach 1:
The conductive films are configured with different widths at different locations: the lower-layer conductive film has a width matching the recess opening to facilitate bump entry, while the upper-layer conductive film is positioned to provide insulation without unnecessarily enlarging the terminal footprint. This local differentiation of dimensions optimizes both bump entry ease and terminal spacing.
Data Source
AI summary
This invention aims at reducing the probability of short-circuiting between terminals in a display device in which an IC driver is connected by COG. Terminals for connection with the IC driver are formed in a terminal region of a TFT substrate (100). The terminals are each comprised of a terminal metal (60), a first through-bole formed in a first insulation film (107), a second through-hole formed in a second insulation film (109), a first ITO (20) formed in the first through-hole and being in contact with the terminal metal (60), and a second ITO (30) formed over the first ITO (20). The second ITO (30) is formed within an area where the second ITO is in contact with the first ITO but is not formed outside the second through-hole. This ensures that the distance between the ITOs of the adjacent terminals can be enlarged, whereby the probability of short-circuiting between the terminals can be lowered.