Light-Emitting Device Substrate Recesses for Joining Strength
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Solution Overview
Problem
Existing light-emitting devices face challenges in achieving a strong joining interface between the substrate and the covering member, leading to potential detachment under external forces or thermal expansion.
Innovation Solution
The design incorporates recesses and through-holes in the substrate, which are covered by a light-reflective covering member, increasing the contact area and joining strength between the substrate and the covering member, and utilizing a covering member with a higher coefficient of linear thermal expansion to prevent detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flat substrate surface is used with a covering member, then the device structure is simple, but the joining strength between substrate and covering member is insufficient leading to potential detachment
Solution Approach 1:
The substrate surface is transformed from a flat two-dimensional plane to a three-dimensional structure with recesses and protrusions. This dimensional change increases the contact area between the substrate and covering member, thereby enhancing joining strength while maintaining structural integrity.
Solution Approach 2:
The substrate surface is divided into multiple recess regions and protrusion regions, creating a segmented structure. This segmentation increases the interlocking area with the covering member, preventing detachment under external forces or thermal expansion.
2Reliability
If the covering member has a higher coefficient of linear thermal expansion than the substrate, then detachment is prevented under thermal expansion, but the material selection becomes more restricted
Solution Approach 1:
The covering member is designed with a higher coefficient of linear thermal expansion than the substrate. During thermal cycling, the covering member expands more than the substrate, creating compressive forces that prevent detachment and improve attachment reliability under thermal expansion conditions.
3Strength
If recesses are added to the substrate to increase contact area, then joining strength is improved, but manufacturing complexity increases
Solution Approach 1:
The substrate surface is transformed from a flat two-dimensional plane to a three-dimensional structure with recesses and protrusions. This dimensional change increases the contact area between the substrate and covering member, thereby enhancing joining strength while maintaining structural integrity.
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
This configuration enhances the joining strength between the substrate and the covering member, preventing detachment even under external forces and thermal expansion, thereby improving the reliability and durability of the light-emitting device.
Implementation Method 1
utilizing a covering member with a higher coefficient of linear thermal expansion to prevent detachment
Data Source
AI summary
A light-emitting device includes a substrate including a base member having an upper surface having a substantially rectangular shape, a lower surface opposite to the upper surface, a first longer lateral surface, a second longer lateral surface opposite to the first longer lateral surface, a first shorter lateral surface, and a second shorter lateral surface opposite to the first shorter lateral surface, first wirings disposed on the upper surface, and second wirings disposed on the lower surface and each electrically connected with a respective one of the first wirings; at least one light-emitting element; and a light-reflective covering member covering lateral surfaces of the light-emitting element and the upper surface of the base member. The base member has at least one first recess open at the upper surface and the first longer lateral surface. Surfaces defining the at least one first recess are covered with the covering member.