LED Current Spreading and Bump Coupling Design
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Solution Overview
Problem
Light emitting diodes (LEDs) face reliability issues due to deterioration in luminous characteristics under high temperature and humidity conditions, current crowding, and low coupling strength between substrates and bumps, leading to separation and reduced luminous efficacy.
Innovation Solution
A light emitting diode design featuring a substrate with a light emitting cell, bumps with concave and convex portions for improved coupling, and a current spreading structure that guides current flow efficiently, while using a silicon nitride insulation layer for moisture-proofing and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lateral arrangement of electrodes is used, then device complexity is reduced, but current crowding occurs in specific regions under high current driving
Solution Approach 1:
The patent transitions from lateral electrode arrangement to vertical stacking architecture, where multiple light emitting cells are stacked in the vertical direction. This dimensional change allows current to spread vertically through multiple cells simultaneously, eliminating current crowding while maintaining manufacturing simplicity through standardized cell stacking.
2Ease of manufacture
If space is left between bumps and insulation layer, then ease of manufacture is improved, but reliability deteriorates
Solution Approach 1:
The patent introduces concave portions in the bumps and corresponding convex portions in the insulation layer, creating complementary curved surfaces that interlock. This curvature-based design eliminates gaps between bumps and insulation layer, improving reliability while maintaining ease of manufacture through self-aligning features during assembly.
3Ease of manufacture
If conventional bump structure is used, then manufacturing is simpler, but coupling strength between substrate and bumps is insufficient
Solution Approach 1:
The patent designs bumps with concave portions and insulation layer with convex portions that fit together like puzzle pieces. This curved, interlocking geometry significantly enhances coupling strength between the substrate and bumps, preventing separation under thermal and mechanical stress while remaining compatible with standard manufacturing processes.
4Object-affected harmful factors
If insulation layer completely covers electrode, then protection is improved, but light extraction efficiency decreases
Solution Approach 1:
The patent applies insulation layer selectively: convex portions are covered for protection, while concave portions remain exposed for light extraction. This localized differentiation allows the same insulation layer to simultaneously provide moisture protection where needed and optical transparency where light must exit, resolving the contradiction between protection and light extraction.
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 design enhances reliability and structural stability under various conditions, improves luminous efficacy by reducing deviation in luminous intensity, and increases coupling strength between the substrate and bumps, preventing separation and maintaining performance over time.
Implementation Method 1
A light emitting diode refers to an inorganic semiconductor device emitting light through recombination of electrons and holes
Implementation Method 2
using a silicon nitride insulation layer for moisture-proofing
Implementation Method 3
bumps with concave and convex portions for improved coupling, increases coupling strength between the substrate and bumps, preventing separation
Implementation Method 4
a current spreading structure that guides current flow efficiently
Data Source
AI summary
A light emitting diode includes a substrate, a lower semiconductor layer disposed on the substrate, a light emitting unit comprising a first upper semiconductor layer disposed in one region of the lower semiconductor layer and an active layer interposed between the lower semiconductor layer and the first upper semiconductor layer, a second current spreading portion comprising a third upper semiconductor layer disposed in another region of the lower semiconductor layer and an active layer interposed between the lower semiconductor layer and the third upper semiconductor layer, a first electrode disposed on the light emitting cell and electrically connected to the first upper semiconductor layer, and a second electrode separated from the light emitting cell and electrically connected to the lower semiconductor layer.