Electro-Optical Device Recessed Substrate Adhesion
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Solution Overview
Problem
Existing electro-optical devices face challenges in securing adhesion between the element substrate and the external coupling substrate due to a step between the mounting terminal and the front surface of the element substrate, which hinders reliable bonding, especially when using anisotropic conductive adhesives.
Innovation Solution
The electro-optical device incorporates a recessed portion on the substrate that communicates with the opening portion of the protective film, allowing air bubbles to escape and increasing the adhesive area by filling the groove portion with anisotropic conductive film, thereby enhancing the contact between the substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing film is thickened to protect the light emission function layer, then the protection capability is improved, but the step between the mounting terminal and the front surface of the element substrate becomes larger, making it difficult to secure adhesion between the element substrate and the external coupling substrate
Solution Approach 1:
The invention introduces a recessed portion that extends in the depth dimension (thickness direction) of the sealing film, communicating with the opening hole. This dimensional change allows the adhesive to flow into the recessed area, increasing the adhesive contact area with the mounting terminal while maintaining the required sealing film thickness for protection. The recessed portion effectively adds a vertical dimension to the adhesive bonding interface, resolving the contradiction between thick sealing film and poor adhesion.
Solution Approach 2:
The opening hole in the sealing film is segmented by introducing a recessed portion that extends downward from the opening. This segmentation divides the opening into an upper horizontal portion and a lower vertical recessed portion, allowing the adhesive to occupy both spaces. The segmented structure increases the total adhesive volume and contact area without increasing the horizontal footprint, thereby improving adhesion while maintaining the protective function of the thick sealing film.
2Reliability
If the mounting terminal is exposed from the opening hole in the sealing film, then electrical coupling is achieved, but a step is formed between the mounting terminal and the front surface, reducing the adhesive contact area
Solution Approach 1:
The recessed portion extends in the depth direction from the opening hole, creating a vertical cavity that the adhesive can fill. This dimensional extension transforms the adhesive interface from a simple surface contact to a volumetric filling, significantly increasing the adhesive contact area with the mounting terminal while maintaining the same horizontal opening dimensions required for electrical coupling.
Solution Approach 2:
The recessed portion is nested within the sealing film structure, extending downward from the opening hole. This nested configuration allows the adhesive to be contained within the recessed cavity, maximizing the adhesive contact area with the mounting terminal without increasing the overall device footprint or compromising the sealing film's protective function.
Data Source
AI summary
An organic EL device includes a substrate including a light-emitting element, a mounting terminal, and a protective film that is provided on the light-emitting element and that has an opening portion overlapping with the mounting terminal in plan view. The substrate has recessed portion that communicates with the opening portion.