Display Substrate Bonding Pad Relocation for Dead Band Reduction
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Solution Overview
Problem
The existing display technologies for mobile devices face challenges due to the 'dead band' created by the flexible circuit's bending radius, which complicates circuit board layout, antenna design, and requires additional space in device housings, leading to larger devices and potential bonding issues.
Innovation Solution
The solution involves relocating the conductive bonding pads from the upper surface of the substrate to the lower surface, eliminating the need for the flexible circuit to bend and thereby reducing the dead band by up to 50-70%, achieved by affixing the pads to the protruding region of the substrate and connecting the flexible circuit conductors to these pads at the folded-back portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flexible circuit is bent to connect the display to driver electronics, then electrical connection is achieved, but additional space is required for the bending radius creating a dead band
Solution Approach 1:
The patent relocates bonding pads from the upper surface to the lower surface of the substrate, utilizing the third dimension (depth/thickness) to resolve the spatial conflict. This allows the flexible circuit to connect without bending in the plane, eliminating the dead band while maintaining electrical connection reliability
Solution Approach 2:
Instead of bending the flexible circuit to achieve connection, the patent inverts the approach by extending the substrate with a protruding region that folds back, allowing the circuit to connect in reverse configuration without requiring bending space
2Area of stationary object
If the flexible circuit is bent with a small bending radius to reduce space, then device size is reduced, but bonding issues and mechanical integrity problems occur
Solution Approach 1:
By moving bonding pads to the lower surface and using a protruding region that folds back, the patent eliminates the need for small-radius bending. The connection is achieved through spatial relocation rather than tight bending, preserving bonding integrity while reducing device space
Solution Approach 2:
The patent utilizes a flexible substrate with a protruding region that can fold back without tension. This flexible structure accommodates the connection geometry change while maintaining mechanical integrity, avoiding the bonding issues associated with small bending radii
3Ease of manufacture
If bonding pads are located on the upper surface of the substrate, then electrical connection is simplified, but the dead band increases requiring larger device housing
Solution Approach 1:
The patent relocates bonding pads from the upper surface to the lower surface of the substrate, utilizing the vertical dimension to eliminate the horizontal dead band. This maintains electrical connection simplicity while reducing the required device housing size by up to 50-70%
Data Source
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AI summary
In accordance with an example embodiment of the present invention, an apparatus includes a substrate (202) having a plurality of conductive traces (212) terminating at a peripheral edge (203) of the substrate (202). An active display portion (204) is disposed on an upper surface of the substrate (202) and electrically coupled to the conductive traces (212) of the substrate (202). The peripheral edge (203) of the substrate (202) includes a protruding region (202') that extends beyond a peripheral edge (205) of the active display portion (204). A plurality of conductive bonding pads (208) are affixed at the protruding region (202') and coupled to the plurality of the conductive traces (212). A flexible circuit (206) includes a plurality of conductors electrically coupled to the plurality of bonding pads (208) at locations on or below a lower surface of the substrate (202).