Display Device Substrate Protrusions Prevent Conductive Ball Flow
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Solution Overview
Problem
Display devices face issues with dark spot defects and short circuits due to the flow of conductive balls in conductive adhesive members connecting light emitting elements and electrode pads, which affect image quality and resolution.
Innovation Solution
The use of protrusions on the substrate, recesses in electrode pads, and a dielectric layer with a reverse taper shape to prevent the flow of conductive balls, increasing contact area and density, and optimizing current injection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive adhesive member with conductive balls is used to connect light emitting element and electrode pad, then electrical connection is achieved, but conductive balls may flow causing dark spot defects and short circuits
Solution Approach 1:
Protrusions are formed on the substrate before mounting the light emitting element and electrode pad. These protrusions are positioned to prevent conductive balls from flowing into non-display areas during the assembly process, thereby preventing dark spot defects and short circuits before they can occur.
Solution Approach 2:
The protrusions act as intermediary structures between the substrate and the conductive adhesive member. They physically block the conductive balls from moving into harmful positions while still allowing the light emitting element and electrode pad to be properly connected through the conductive balls in the display area.
2Reliability
If protrusions are added to prevent conductive ball flow, then dark spot defects are suppressed, but device structure becomes more complex
Solution Approach 1:
The protrusions are integrated with the substrate structure itself, forming a unified component rather than being separate added elements. This merging approach minimizes the increase in device complexity while still providing the necessary function to prevent conductive ball flow.
Data Source
AI summary
A display device includes a substrate, a plurality of electrode pads including a first electrode pad and a common electrode pad on the substrate, a light emitting element including a first contact electrode on the first electrode pad and a second contact electrode on the common electrode pad, a conductive adhesive member including a plurality of conductive balls connecting the first electrode pad and the first contact electrode and connecting the common electrode pad and the second contact electrode, and a plurality of protrusions on the substrate and protruding in a thickness direction of the substrate. First protrusions from among the plurality of protrusions overlap the electrode pads in the thickness direction of the substrate.