Flip-Chip LED Connector Spacing for Electrical Reliability
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Solution Overview
Problem
Light emitting diodes (LEDs) face issues with electric short circuits between bump pads and conductive metal layers due to insulation layer damage from particles or electrical testing, leading to reliability concerns and failure.
Innovation Solution
A flip-chip type LED design with strategically spaced connectors and floating metal layers to prevent short circuits, enhancing electrical reliability and light extraction efficiency by ensuring the connectors do not overlap with bump pads and using floating metal layers to reflect light without causing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If connectors are disposed close to bump pads to reduce device area, then area is reduced, but electric short circuit occurs between connectors and bump pads due to insulation layer damage
Solution Approach 1:
The patent introduces a vertical layering dimension by disposing the connector and bump pad at different height levels. The connector is positioned at a first height level while the bump pad is positioned at a second height level different from the first, creating vertical separation that prevents horizontal short circuiting while maintaining compact planar area.
Solution Approach 2:
The patent introduces an insulation layer as an intermediary element between the connector and bump pad. This insulation layer is disposed between the connector and the bump pad to provide electrical isolation, preventing direct contact and potential short circuits while allowing both elements to function independently.
2Device complexity
If insulation layer is made thinner to reduce device complexity, then manufacturing is simplified, but insulation effectiveness decreases leading to short circuits
Solution Approach 1:
Instead of relying solely on insulation layer thickness, the patent transitions to a multi-level vertical architecture where the connector and bump pad are disposed at different height levels. This dimensional approach provides inherent spatial separation that maintains insulation effectiveness without depending on thin layer precision.
Solution Approach 2:
The patent segments the device structure into distinct vertical layers, with the connector at a first height level and the bump pad at a second height level. This segmentation creates natural electrical isolation zones that simplify the insulation requirement compared to relying on a single continuous thin insulation layer.
3Illumination intensity
If connectors overlap with bump pads to improve light extraction efficiency, then light extraction is enhanced, but electric short circuit occurs between connectors and bump pads
Solution Approach 1:
The patent resolves the conflict between light extraction and electrical isolation by utilizing the vertical dimension. The connector and bump pad are disposed at different height levels, allowing their horizontal projections to overlap for light extraction enhancement while maintaining vertical electrical isolation to prevent short circuits.
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 solution effectively prevents short circuits and improves light extraction efficiency by ensuring reliable electrical connections and efficient heat dissipation, thereby enhancing the overall reliability and performance of the LED.
Implementation Method 1
an ohmic reflection layer disposed on the second conductivity type semiconductor layer of each of the light emitting cells to form ohmic contact therewith
Implementation Method 2
a connector disposed on the lower insulation layer and electrically connecting adjacent light emitting cells to each other to form a series array of light emitting cells
Implementation Method 3
floating metal layers to reflect light without causing short circuits
Data Source
AI summary
Disclosed herein is a highly reliable light emitting diode. In the light emitting diode, a connector connecting light emitting cells to each other is spaced apart from bump pads in a lateral direction so as not to overlap each other. Accordingly, it is possible to provide a chip-scale flip-chip type light emitting diode having good properties in terms of heat dissipation performance and electrical reliability.