Conductive Bonding Structure With Slit Transfer Pad
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Solution Overview
Problem
The existing conductive bonding structures for substrates in display devices face challenges in achieving reliable bonding and alignment, leading to potential electrical connectivity issues and increased resistance, particularly due to misalignment and the need for improved contact areas.
Innovation Solution
A conductive bonding structure featuring a lower substrate with a connection pad and an upper substrate with a transfer pad that includes a slit with an extending portion and an expansion portion, allowing the solder to contact both pads and increasing the contact area, thereby enhancing bonding reliability and alignment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bonding structure with direct pad contact is used, then the structure is simple, but the contact area is insufficient leading to increased electrical resistance
Solution Approach 1:
The patent introduces a vertical dimension to the bonding interface by creating a recess in the bonding pad that extends downward into the substrate. This vertical recess increases the contact area between bonding surfaces without expanding the horizontal footprint, thereby improving electrical connectivity and bonding reliability while maintaining compact alignment tolerances.
Solution Approach 2:
The bonding pad is designed with non-uniform geometry, featuring a recessed region with different depth and width characteristics at specific locations. This local variation concentrates the contact area in critical zones, optimizing electrical resistance at the bonding interface while the overall pad structure maintains mechanical stability and alignment capability.
2Reliability
If the contact area between solder and pads is increased to reduce electrical resistance, then electrical conductivity improves, but the structure becomes more complex
Solution Approach 1:
The patent introduces a vertical dimension to the bonding interface by creating a recess in the bonding pad that extends downward into the substrate. This vertical recess increases the contact area between bonding surfaces without expanding the horizontal footprint, thereby improving electrical connectivity and bonding reliability while maintaining compact alignment tolerances.
Solution Approach 2:
The bonding pad is designed with non-uniform geometry, featuring a recessed region with different depth and width characteristics at specific locations. This local variation concentrates the contact area in critical zones, optimizing electrical resistance at the bonding interface while the overall pad structure maintains mechanical stability and alignment capability.
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
The proposed structure improves bonding reliability and alignment by increasing the contact area between the solder and the pads, reducing electrical resistance, and preventing electrical shorts, while also allowing for a thinner display device design.
Implementation Method 1
a solder contacting an upper surface of the connection pad and an upper surface of the transfer pad
Data Source
AI summary
A substrate conductive bonding structure includes a lower substrate including a connection pad exposed to outside the lower substrate, an upper substrate including a transfer pad overlapping the connection pad, exposed to outside the upper substrate and including an upper surface, and a slit defined in the transfer pad, overlapping the connection pad and open at the upper surface of the transfer pad, the slit including an extending portion extending along a first direction and having a first slit width along a second direction crossing the first direction, and an expansion portion connected to the extending portion and having a second slit width along the second direction which is larger than the first slit width, and a solder contacting the upper surface of the connection pad, extending to the upper surface of the transfer pad and into the slit.