3D Stacked Display Element with Drive IC and Flexible Substrate
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Solution Overview
Problem
Existing electro-optical devices face challenges in achieving stable connections between the drive integrated circuit, the electro-optical panel, and the flexible printed circuit (FPC), due to differences in elastic modulus and requiring precise dimensional accuracy for terminal pads.
Innovation Solution
The proposed display element design includes a substrate with light emitting elements, a drive integrated circuit with a drive circuit, and a flexible substrate, where the drive integrated circuit is disposed on one surface of the substrate, and the flexible substrate is disposed on a surface of the drive integrated circuit opposite to the substrate. This configuration enhances the stability of connections using conductive connecting members and conductive structures like through holes and side-surface wiring lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the drive integrated circuit and flexible substrate are disposed on the same surface of the substrate, then the substrate area must be sufficiently large to accommodate all components, but this increases the overall display element area
Solution Approach 1:
The patent transitions from a two-dimensional layout where all components are arranged on the same surface to a three-dimensional stacked configuration. The drive integrated circuit is disposed on the first surface of the substrate, while the flexible substrate is disposed on the second surface (opposite surface) of the substrate. This vertical stacking approach reduces the horizontal area requirement while maintaining all necessary connection pathways through the substrate thickness.
2Reliability
If terminal pads are pressure-bonded with anisotropic conductive film, then connection is achieved, but dimensional accuracy and elastic modulus differences reduce connection stability
Solution Approach 1:
The patent introduces conductive structures (such as conductive paste, conductive resin, or anisotropic conductive films) as intermediary bonding materials between the terminal pads of the drive integrated circuit and the flexible substrate. These intermediary materials compensate for dimensional inaccuracies and elastic modulus differences by providing compliant bonding that maintains electrical connectivity while accommodating manufacturing tolerances and mechanical property variations.
3Reliability
If terminal pads are pressure-bonded with anisotropic conductive film, then connection is achieved, but elastic modulus differences between FPC and IC element reduce connection stability
Solution Approach 1:
The patent modifies the mechanical parameters of the bonding interface by using conductive structures with appropriate elastic modulus values that are intermediate between the rigid drive integrated circuit and the flexible substrate. This parameter adjustment allows the bonding layer to act as a mechanical buffer, absorbing stress caused by elastic modulus differences and maintaining stable electrical connections under varying mechanical conditions.
Data Source
AI summary
The present disclosure provides a display element that is capable of reducing the area of a substrate including light emitting elements and has an enhanced stability of connection of a drive integrated circuit to the substrate and a flexible substrate, and also provides an electronic device using the display element. The display element includes: a substrate that includes a light emitting element disposed therein, and has a light emitting surface; a drive integrated circuit including a drive circuit that controls driving of the light emitting element; and a flexible substrate having a connecting terminal. In the display element, the drive integrated circuit is disposed on one surface of the substrate, and the flexible substrate is disposed on the side of a surface of the drive integrated circuit, the surface not facing the substrate.