Light Emitting Device Bump Arrangement for Uniform Luminance
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Solution Overview
Problem
Existing light emitting devices face challenges in achieving uniform luminance distribution and heat dissipation, leading to potential cracks in the insulation film and light leakage due to uneven current density and heat distribution.
Innovation Solution
A light emitting device manufacturing method involving a substrate with a wiring pattern and bumps of varying sizes, where first large bumps and first small bumps are arranged to avoid overlapping with exposed semiconductor layers, allowing for dense bonding and uniform current distribution, and a cover member is formed to prevent voids and enhance heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform bump arrangement is used, then manufacturing simplicity is maintained, but luminance distribution uniformity deteriorates
Solution Approach 1:
The patent applies local quality by varying bump sizes based on position: first large bumps are placed in regions farther from the light emitting element to provide stronger heat dissipation and current distribution in those areas, while first small bumps are placed in regions closer to the light emitting element. This positional differentiation resolves the contradiction by optimizing luminance uniformity through localized adaptation rather than uniform arrangement.
2Strength
If bumps are placed densely, then bonding strength increases, but current density uniformity deteriorates
Solution Approach 1:
The patent implements local quality by using different bump sizes in different regions: first large bumps in outer regions provide greater bonding area and strength where needed, while first small bumps in inner regions maintain appropriate current density distribution. This resolves the contradiction by allowing dense arrangement overall while maintaining current uniformity through localized size variation.
Solution Approach 2:
The patent applies asymmetry by using non-uniform bump sizes (first large bumps vs. first small bumps) in a symmetric grid pattern. This asymmetric size differentiation within a symmetric arrangement allows dense bonding throughout while preventing current density concentration, resolving the contradiction between bonding strength and current uniformity.
3Volume of moving object
If insulation film is made thin, then device size is reduced, but crack resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the insulation film thickness to a specific range (1 μm to 10 μm) that balances device miniaturization with crack resistance. Additionally, the bump size variation and arrangement pattern modify stress distribution parameters, allowing thin insulation film while maintaining reliability through compensated stress management.
4Temperature
If heat dissipation is enhanced, then thermal management improves, but light leakage increases
Solution Approach 1:
The patent applies local quality by concentrating heat dissipation functions in the first large bumps positioned in outer regions away from the light emitting element, while first small bumps in inner regions maintain appropriate thermal management without compromising light extraction. This spatial differentiation resolves the contradiction by localizing heat dissipation pathways away from light-emitting zones.
Data Source
AI summary
A method for manufacturing a light emitting device includes: providing a substrate defining a mounting region having a wiring pattern on an upper face thereof; forming a plurality of bumps arranged in a plurality of columns extending parallel to each other with a distance between adjacent ones of the bumps in one of the columns arranged closest to an outer edge of the mounting region is larger than a distance between adjacent ones of the bumps arranged on an inner side in a plan view, and the bumps include first bumps and second bumps with the first bumps including first large bumps and first small bumps, with all the bumps in the one of the columns arranged closest to the outer edge are the same size; mounting the light emitting element onto the bumps in a flip-chip manner; and forming a cover member.