Display Device Resin Buffer for Thermocompression Bonding
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Solution Overview
Problem
Existing display devices face reliability issues due to pressure-induced damage during thermocompression bonding, particularly when using flexible substrates, which can lead to cracks in elements and wiring, and they have a large frame width and high cost.
Innovation Solution
A display device design featuring a conductive layer exposed in a resin layer opening, with a resin layer acting as a sealant and spacer, allowing for pressure buffering during bonding and reducing frame width and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermocompression bonding is used to bond FPC and terminal portion, then electrical connection is achieved, but pressure causes damage to elements and wiring
Solution Approach 1:
A resin layer is introduced as an intermediary between the FPC and the terminal portion on the substrate. This resin layer absorbs and distributes the pressure during thermocompression bonding, preventing direct transmission of harmful pressure to the elements and wiring while still enabling electrical connection through the conductive layer exposed in the opening.
Solution Approach 2:
The resin layer is positioned in advance before bonding to provide cushioning protection. It pre-absorbs the bonding pressure, creating a buffer that protects vulnerable elements and wiring from damage before the bonding process completes, thereby ensuring connection reliability without pressure-induced damage.
2Adaptability or versatility
If flexible substrate is used, then flexibility and cost are improved, but substrate deformation causes cracks in elements and wiring
Solution Approach 1:
The resin layer acts as a mediator between the flexible substrate and the rigid elements/wiring. It accommodates substrate deformation while maintaining structural support for the elements, preventing cracks from forming even when the flexible substrate bends or deforms.
3Reliability
If conventional bonding structure is used, then connection is achieved, but frame width is large
Solution Approach 1:
The conductive layer is exposed in an opening of the resin layer, creating a vertical/dimensional connection path rather than requiring lateral extension. This allows the FPC to connect to the terminal portion through the thickness direction, reducing the horizontal frame width while maintaining connection functionality.
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 solution enhances the reliability of display devices by preventing damage from pressure, reduces frame width, and lowers production costs.
Implementation Method 1
a resin layer acting as a sealant and spacer, allowing for pressure buffering during bonding
Implementation Method 2
a connector such as the FPC and an electrode of a terminal portion provided on a substrate are bonded together through an anisotropic conductive film and brought into conduction by thermocompression bonding
Data Source
AI summary
A highly reliable display device is provided. The display device includes a first substrate, a first resin layer over the first substrate, a pixel portion and a terminal portion over the first resin layer, a second resin layer over the terminal portion, and a second substrate over the second resin layer. The pixel portion includes a transistor and a display element electrically connected to the transistor. The terminal portion includes a conductive layer. The first resin layer includes an opening. The conductive layer includes a first region that is exposed in the opening in the first resin layer. The second resin layer includes a region overlapping with the first region. The conductive layer is the same layer as at least one of a gate of the transistor and a source and a drain of the transistor.