Flexible Display Pad Electrode Routing for Bonding Stress Reduction
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Solution Overview
Problem
The existing methods for manufacturing flexible displays face challenges with bonding stress due to the high pressure required in the press-cure process, which deforms soft plastic films and reduces manufacturing efficiency, especially as displays become larger and thinner.
Innovation Solution
The flexible display design exposes the pad electrode of the touch electrode array outside the display, allowing direct bonding to a flexible printed circuit, eliminating the need for high-pressure bonding and enabling local connection using a conductive adhesive, thus avoiding deformation and equipment constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure is applied in the press-cure process to bond the anisotropic conductive film, then the touch pad electrode and auxiliary pad electrode are interconnected, but the soft plastic base films are deformed and manufacturing efficiency is reduced
Solution Approach 1:
The patent extracts the bonding process from the internal structure by routing the touch pad electrode outside the flexible display. This allows the electrode to be directly bonded to the flexible printed circuit without requiring high-pressure press-curing through the base films, thereby eliminating base film deformation while maintaining electrical connection reliability
Solution Approach 2:
The patent uses the flexible printed circuit as an intermediary element that receives the touch pad electrode outside the display structure. This intermediary approach enables direct bonding without applying pressure to the base films, solving both the connection reliability and deformation prevention requirements
2Reliability
If high pressure is applied uniformly across the entire surface to bond the anisotropic conductive film, then the electrodes are interconnected, but larger displays require bigger apparatus and manufacturing efficiency is reduced
Solution Approach 1:
The patent extracts the bonding operation from the entire display surface by positioning the touch pad electrode outside the flexible display. This enables localized bonding using a simple apparatus, eliminating the need for large-scale uniform pressure application equipment required for bigger displays
Solution Approach 2:
The patent applies bonding only at the specific location where the touch pad electrode contacts the flexible printed circuit outside the display. This localized bonding approach uses a small, simple apparatus regardless of display size, maintaining connection reliability without requiring complex large-scale equipment
3Length of moving object
If the display is made thinner to reduce overall size, then the display thickness is reduced, but the base films have low resistance during press-cure process reducing yield
Solution Approach 1:
The patent extracts the bonding process from the thin base film structure by routing the electrode outside the display. This eliminates the press-cure process through the thin base films, preventing the low-resistance defect that reduces manufacturing yield while maintaining the thin display design
Data Source
AI summary
A flexible display device includes a touch electrode array including a buffer layer with a through hole in the buffer layer, a touch pad metal electrode in the through hole, a plurality of touch patterns on the buffer layer, and a flexible printed circuit contacting the touch pad electrode. Optionally, the flexible printed circuit can also contact a thin-film transistor pad on an organic light emitting array substrate laminated to the touch electrode array.