Light Emitting Device with Stainless Steel Substrate and Conductive Members
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Solution Overview
Problem
Conventional light emitting devices face challenges in reducing thickness, improving light extraction efficiency, and enhancing heat resistance while maintaining manufacturing yield, particularly due to the use of double-sided through-hole printed-circuit boards and irregular surface configurations which can lead to breakage and low contrast in displays.
Innovation Solution
A method of manufacturing light emitting devices involving a stainless steel substrate with conductive members having Au and a metallic layer with a lower diffusion coefficient, bonded with a light-blocking resin and an optically transmissive sealing member, allowing for thin, high-efficiency devices with improved heat resistance and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double-sided through-hole printed-circuit board is used to mount the light emitting element, then the device has good structural stability and electrical connection, but the device thickness increases to 0.1 mm or more
Solution Approach 1:
The patent extracts and removes the printed-circuit board from the device structure, replacing it with a substrate that integrates the light emitting element and electrode directly. This eliminates the need for separate through-hole mounting while maintaining electrical connection functionality, thereby reducing device thickness without compromising structural stability.
Solution Approach 2:
The patent merges the substrate, light emitting element, and electrode into a single integrated structure. The light emitting element is mounted directly on the substrate with electrodes formed on the same substrate, combining multiple previously separate components into one unified assembly, which significantly reduces overall device thickness.
2Device complexity
If only optically transmissive resin is used to seal the light emitting element, then the device structure is simple, but light extraction efficiency decreases due to light escaping through the bottom surface
Solution Approach 1:
The patent uses a composite sealing structure consisting of both optically transmissive resin and reflective resin. The optically transmissive resin allows light to pass through the top surface, while the reflective resin at the bottom surface reflects escaping light back upward. This composite approach maintains structural simplicity while significantly improving light extraction efficiency by preventing light loss through the bottom surface.
3Loss of energy
If a cone-shaped metallic film is formed to reflect light and improve extraction efficiency, then light extraction efficiency improves, but the substrate requires an irregular surface configuration that is difficult to process and causes breakage
Solution Approach 1:
Instead of forming a complex cone-shaped metallic film on an irregular substrate surface, the patent inverts the approach by using a flat substrate surface with a reflective resin layer. The light reflection function is achieved through the material property of the reflective resin rather than through complex geometric shaping, thereby eliminating processing difficulties and breakage risks while maintaining light extraction efficiency.
Solution Approach 2:
The patent replaces the mechanical/geometric approach of cone-shaped metallic film structures with a material-based approach using reflective resin. Instead of relying on physical geometry (cone shape) to achieve light reflection, the invention uses the optical properties of reflective material, simplifying the manufacturing process and eliminating the need for complex surface configurations.
4Power
If the output power of the light emitting element is increased to generate higher power, then the luminous output improves, but the amount of heat generated increases requiring better heat resistance
Solution Approach 1:
The patent introduces a heat-resistant adhesive member as an intermediary between the light emitting element and the substrate. This adhesive member serves as a thermal interface that can withstand high temperatures generated by high-power operation, allowing the device to achieve higher luminous output without compromising structural integrity due to heat accumulation.
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 approach results in thin, high-luminous efficiency light emitting devices with excellent heat-resistant properties and improved manufacturing yield, preventing light leakage and enhancing contrast for display applications.
Implementation Method 1
The second region contains a metallic member having a diffusion coefficient with respect to a metal contained in the stainless steel smaller than a diffusion coefficient of Au with respect to the metal contained in the stainless steel
Implementation Method 2
forming a base member made of a light-blocking resin on the supporting substrate
Implementation Method 3
covering the light emitting element with an optically transmissive sealing member
Implementation Method 4
applying heat at a temperature lower than the melting point of the metallic layer to melt the adhesive member
Data Source
AI summary
A method of manufacturing a light emitting device includes: a first step of forming on a supporting substrate made of a stainless steel, a plurality of conductive members each including a first region containing Au and a second region containing a metallic member having a diffusion coefficient with respect to a metal in the stainless steel smaller than a diffusion coefficient of Au with respect to the metal in the stainless steel, a second step of forming a base member made of a light-blocking resin on the supporting substrate between the conductive members, a third step of bonding a light emitting element on an upper surface of a conductive member through an adhesive member, a fourth step of covering the light emitting element with an optically transmissive sealing member, and a fifth step of removing the supporting substrate and individually separating the light emitting devices.