Light-Emitting Device Lateral Bonding for Tombstone Prevention
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Solution Overview
Problem
Light-emitting devices mounted on a mounting board often experience inclination due to the pulling of bonding members, leading to undesired orientations and potential tombstone phenomena, which can result in reduced light emission and increased risk of chipping or deformation.
Innovation Solution
The light-emitting device features a first metal film on the lower surface and a second metal film on the lateral surface, with the second metal film having a larger area or longer length than the first, to provide a stable mounting surface and reduce the inclination risk by increasing the bonding area and heat dissipation, while preventing the bonding member from flowing onto the light-emitting surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the light-emitting device is mounted via bonding member on the lower surface, then the device can be fixed on the mounting board, but the bonding member causes pulling force that inclines the device and creates tombstone phenomenon
Solution Approach 1:
The patent extends the bonding area from a single lower surface to both the lower surface and the lateral surface, creating a three-dimensional bonding structure. The metal films are formed on multiple surfaces (lower surface and lateral surface) to distribute the bonding force across different spatial dimensions, preventing inclination caused by concentrated pulling force on the lower surface alone.
Solution Approach 2:
The bonding structure is segmented into multiple metal films located on different surfaces. Instead of a single bonding interface, the patent divides the bonding function across multiple locations (lower surface metal films and lateral surface metal films), with each segment contributing to the overall bonding strength while distributing mechanical stress.
2Force
If the bonding area is increased to prevent inclination, then the fixing force is improved, but the device complexity increases
Solution Approach 1:
The metal films serve multiple functions simultaneously: they provide electrical connection, thermal management, and mechanical bonding. By making the metal films multi-functional, the patent increases fixing force without adding separate components, thereby avoiding increased device complexity.
Solution Approach 2:
The patent merges the bonding function with the existing electrical and thermal management structures. The metal films that would normally serve only electrical purposes are extended to also serve as bonding interfaces, combining multiple functions into a single integrated structure rather than adding separate bonding components.
Data Source
AI summary
A light-emitting device having an upper surface, a lower surface opposite to the upper surface, and a first lateral surface, the upper surface serving as a light-emitting surface, the first lateral surface being adjacent and orthogonal to the upper surface, the first lateral surface serving as a mounting surface, the light-emitting device including: a pair of a first metal films disposed at the lower surface; and a pair of second metal films disposed at the first lateral surface; wherein an area of each of the second metal films is larger than an area of each of the first metal films.