ACF Terminal Structure for Flexible Display Warping Control
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Solution Overview
Problem
Flexible organic EL display devices experience warping issues due to heat and load applied during compression-bonding of ICs to flexible substrates via anisotropic conductive films.
Innovation Solution
Incorporating a protruding portion on the electrode insulating film that overlaps with the IC and input/output bumps, reducing warping by distributing stress more evenly during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an IC is compression-bonded to a flexible substrate via an anisotropic conductive film, then electrical connectivity is achieved, but the flexible substrate becomes warped due to heat and load applied during bonding
Solution Approach 1:
The patent applies local quality by providing a protruding portion at specific locations on the electrode insulating film that overlaps with the IC and bumps. This localized structural modification concentrates stress support where needed during compression bonding, preventing substrate warping while maintaining electrical connectivity through the ACF.
Solution Approach 2:
The protruding portion extends in the thickness direction of the flexible substrate, adding a vertical dimension to the stress distribution. This three-dimensional structure helps distribute the bonding load more evenly through the substrate thickness, reducing warping caused by planar compression forces.
2Shape
If a protruding portion is added to the electrode insulating film, then substrate warping is reduced, but device structure becomes more complex
Solution Approach 1:
Rather than modifying the entire electrode insulating film uniformly, the protruding portion is localized to specific regions overlapping with the IC and bumps. This targeted approach reduces structural complexity compared to a comprehensive redesign, addressing warping only where the bonding stress is most concentrated.
Solution Approach 2:
The electrode insulating film is effectively segmented into regions with and without protruding portions. This segmentation allows the structure to maintain simplicity in non-critical areas while providing enhanced warping resistance only where needed during IC compression bonding.
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 protruding portion effectively reduces substrate warping, minimizes stress on insulating layers, and maintains mechanical and electrical connectivity, thereby enhancing the durability and performance of the display device.
Implementation Method 1
compression-bonding an IC to a flexible substrate via an anisotropic conductive film (ACF)
Implementation Method 2
when an IC is compression-bonded to a flexible substrate
Data Source
AI summary
A terminal connection portion, which includes an IC including a plurality of input bumps and a plurality of output bumps, and a terminal connection portion including a plurality of input terminal electrodes and a plurality of output terminal electrodes, is provided in a frame region, and in the terminal connection portion, an electrode insulating film is provided on the input terminal electrodes and the output terminal electrodes. A protruding portion is provided on the electrode insulating film, and the protruding portion overlaps with the IC in a plan view, and overlaps with the input bumps and the output bumps when viewed from a direction parallel to a substrate surface of a resin substrate layer.