Staggered Mounting Terminal Substrate for COG Alignment
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Solution Overview
Problem
In small-size liquid-crystal display devices, the narrow pitch of mounting terminals leads to reduced positional alignment margins during COG mounting, resulting in increased failures of electrical conduction due to insufficient bonding and contact resistance issues.
Innovation Solution
A mounting terminal substrate design with staggered rows of mounting terminals, where the upper conductive film is wider than the lower conductive film and covers it, and the opening sections are widened to accommodate positional errors, ensuring reliable electrical conduction and reduced contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mounting terminals are arranged in staggered rows to reduce pitch, then the terminal pitch is reduced to about 35 μm, but the margin of error in positional alignment between bumps and opening sections becomes smaller
Solution Approach 1:
The mounting terminal is designed with asymmetric structure where the upper conductive film width is greater than the lower conductive film width. This asymmetric design creates a stepped configuration that increases the effective opening section width, thereby providing a larger margin of error for positional alignment during COG mounting while maintaining the narrow pitch of 35 μm.
Solution Approach 2:
The invention extends the terminal structure in the vertical dimension by creating a stepped configuration with upper and lower conductive films at different levels. This dimensional extension effectively increases the opening section width without increasing the horizontal pitch, allowing for better alignment tolerance in the staggered row arrangement.
2Manufacturing precision
If the opening section width is reduced to maintain terminal pitch, then the terminal pitch can be reduced to 35 μm, but the contact area between bumps and mounting terminals is reduced, increasing conduction resistance
Solution Approach 1:
The asymmetric design with wider upper conductive film compensates for the reduced opening section width by providing additional contact area. The stepped configuration ensures that even with narrow pitch, the effective bonding area is sufficient to maintain low conduction resistance.
Solution Approach 2:
The mounting terminal uses a composite structure with multiple conductive film layers (upper and lower conductive films) with different widths. This composite configuration increases the effective contact area and improves electrical conduction while maintaining the narrow terminal pitch required for high-resolution displays.
3Manufacturing precision
If the opening section width is reduced to maintain terminal pitch, then the terminal pitch can be reduced to 35 μm, but the overlap area between bumps and mounting terminals is reduced, increasing the risk of electrical conduction failure
Solution Approach 1:
The asymmetric stepped configuration with wider upper conductive film creates a larger effective overlap area with the bumps. This design ensures sufficient conductive particle engagement and bonding area, maintaining electrical conduction reliability even when the terminal pitch is reduced to 35 μm in staggered row arrangements.
Solution Approach 2:
By extending the terminal structure vertically with multiple conductive film layers at different levels, the invention increases the effective bonding area in the vertical dimension. This compensates for the reduced horizontal overlap area, ensuring reliable electrical conduction at narrow pitches.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the margin of positional alignment error, improving conduction reliability and reducing the risk of electrical conduction failures and contact resistance in COG mounting, while maintaining the structural integrity of the substrate.
Implementation Method 1
the substrate is subjected to thermo-compression bonding, whereby electrical conduction is established by way of the conductive particles
Implementation Method 2
an insulation film for protecting wiring or a mounting terminal area has been partially removed
Data Source
AI summary
A mounting terminal substrate includes a substrate, mounting terminals arranged in staggered rows on the substrate, each mounting terminals includes a lower conductive film and an upper conductive film, lines that are provided between the mounting terminals in a direction of a row, an insulation film that covers the lines, and opening sections on the respective mounting terminals from which the insulation films are removed, wherein a width of the upper conductive film in the direction of the row is greater than a width of the lower conductive film in the direction of the row so as to cover the lower conductive films exposed through the opening sections and is equal to or smaller than a width of the opening section in the direction of the row.