Light-emitting device with reflective member reducing light absorption
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Solution Overview
Problem
The light extraction efficiency of light-emitting devices using anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) connection techniques is compromised due to light absorption by exposed electrodes, and the adhesive fillet formed during mounting can increase the amount of conductive particles on the side surface, further reducing efficiency.
Innovation Solution
A light-emitting device configuration that includes a substrate with electrodes and an insulating reflective member, where the reflective member covers the entire surface below the resin member, reducing the thickness and area of the adhesive fillet and minimizing light absorption, and using a conductive substance with pointed ends to effectively connect the light-emitting element to the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are exposed and opposed to the light-emitting element to enable connection, then electrical connection is achieved, but light extraction efficiency decreases due to light absorption by the exposed electrodes
Solution Approach 1:
The patent introduces a reflective member as an intermediary substance between the exposed electrodes and the light-emitting element. This reflective member serves dual functions: it maintains the electrical connection pathway while simultaneously reflecting light that would otherwise be absorbed by the electrodes, thereby resolving the contradiction between achieving reliable electrical connection and maintaining high light extraction efficiency
Solution Approach 2:
The reflective member is designed with high reflectivity properties (optical reflectance of 80% or more) to change the optical interaction from absorption to reflection. By modifying the optical properties of the interface between electrodes and light-emitting element, the system achieves both electrical connectivity and light extraction efficiency
2Strength
If adhesive fillet area is increased to ensure mechanical bonding strength, then mechanical strength is improved, but the amount of conductive particles on the side surface increases, further reducing light extraction efficiency
Solution Approach 1:
The patent applies local quality by concentrating the adhesive fillet only where mechanically necessary (at the peripheral portion of the light-emitting element) rather than covering the entire side surface. This localized application maintains adequate mechanical bonding strength while minimizing the total amount of conductive particles present on side surfaces, thereby reducing light absorption and improving light extraction efficiency
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 light extraction efficiency by reducing light absorption and maintaining mechanical strength, while also simplifying the manufacturing process and reducing costs by minimizing the need for complex patterning and underfill materials.
Implementation Method 1
the reflective member being disposed at least over an entirety of a surface that is located immediately below the resin member
Implementation Method 2
the conductive particles are caught between electrodes of the light-emitting element and electrodes of the substrate to establish an electrical connection
Implementation Method 3
The ACP is a dispersion of conductive particles in an adhesive such as an epoxy thermosetting resin
Data Source
AI summary
A light-emitting device includes a support including a substrate, a pair of electrodes and an insulating reflective member, the pair of electrodes being disposed on an upper surface of the substrate, and the reflective member being disposed on the substrate, a light-emitting element flip-chip mounted on the pair of electrodes, and a resin member disposed at least between the light-emitting element and the reflective member, the resin member including a conductive substance which electrically connects the light-emitting element to the pair of electrodes, the reflective member being disposed at least over an entirety of a surface that is located immediately below the resin member.