Flexible Display Driver IC Double-Layer Structure
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Solution Overview
Problem
Flexible display devices face issues with subsidence damage and cracks in the driver IC during thermal compression due to the presence of a shock absorbing member, which is not effectively addressed by existing manufacturing methods.
Innovation Solution
A flexible display device with a driver IC formed as a double layer, featuring protruding layers corresponding to bump locations, which prevents or reduces subsidence damage and cracks by distributing pressure evenly during thermal compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal compression is applied to attach the driver IC to the substrate, then the driver IC is securely fixed to the substrate, but subsidence damage and cracks occur in the driver IC around the bumps due to the shock absorbing member pressing the center portion
Solution Approach 1:
The driver IC structure is modified to have different properties in different locations: protruding layers are added at specific locations corresponding to bump positions, while other areas maintain the original single-layer structure. This local differentiation allows the protruding layers to bear the compression load during thermal compression, preventing subsidence damage and cracks in the bump areas while maintaining secure attachment.
Solution Approach 2:
The protruding layers are pre-formed on the driver IC before the thermal compression process. These protruding layers are positioned to correspond with the bump locations, so that when thermal compression occurs, the load is already distributed to these reinforced areas, preventing subsidence damage before it can occur.
2Ease of manufacture
If a shock absorbing member is provided between the compression tool and the driver IC during thermal compression, then the compression process can be performed, but the shock absorbing member presses the center portion of the driver IC causing subsidence damage and cracks around the bumps
Solution Approach 1:
Instead of modifying the compression process, the driver IC itself is modified with local protruding layers at bump locations. This allows the standard shock absorbing member to be used while the localized structural enhancement protects the critical bump areas from subsidence damage during compression.
Solution Approach 2:
The protruding layers act as pre-formed protective structures that cushion the bump areas against the pressing force during thermal compression. By having these protective elements in place before compression, the driver IC is protected from subsidence damage without requiring modification to the compression tool or process.
3Reliability
If the driver IC is formed as a double layer with protruding layers at bump locations, then subsidence damage and cracks are prevented during thermal compression, but the device complexity increases
Solution Approach 1:
The driver IC is not converted to a complete double-layer structure, but rather has localized protruding layers added only at the bump positions. This selective approach provides the necessary damage protection while minimizing the increase in overall device complexity compared to a full double-layer construction.
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 double-layer structure of the driver IC with protruding layers effectively mitigates subsidence damage and cracks, ensuring reliable operation and durability of the flexible display device during thermal compression processes.
Implementation Method 1
The base layer may be attached to the substrate by an anisotropic conductive film
Implementation Method 2
The driver IC is attached to an outer portion of the substrate by thermal compression, and a compression tool applies a predetermined temperature and pressure to the driver IC such that the driver IC is compressed
Data Source
AI summary
A flexible display device according to an example embodiment includes: a substrate; a driver integrated circuit (IC) in a non-display portion of the substrate and configured to supply a driving voltage to a display portion of the substrate; a flexible printed circuit board attached to the non-display portion at an outer side of the driver IC; and a printed circuit board attached to the flexible printed circuit board and configured to transfer the driving voltage to the driver IC, wherein the driver IC comprises a base layer, a plurality of bumps at a bottom surface of the base layer, a first layer at an upper surface of the base layer, and second layers at the first layer to correspond to locations of the plurality of bumps.