Resin Package LED Light Extraction
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Solution Overview
Problem
Conventional light emitting diode (LED) devices with double-sided through-hole printed circuit boards face challenges in reducing thickness and processing accuracy, leading to poor light extraction efficiency and reliability, especially when used in display applications.
Innovation Solution
A resin package with a recessed design featuring a conductive member and a protruding portion on the curved surface of the side wall, integrated with a thermosetting resin base body, enhances light extraction efficiency and reliability by preventing light leakage and improving adhesion between components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double-sided through-hole printed circuit board is used to mount the light emitting diode element, then the device structure is stable and reliable, but the thickness cannot be reduced below about 0.1 mm and processing accuracy is poor
Solution Approach 1:
The invention extracts and removes the double-sided through-hole printed circuit board from the device structure, replacing it with a resin package that integrates the light emitting diode element directly. This elimination of the thick PCB substrate enables significant thickness reduction while maintaining device reliability through the integrated resin package design.
Solution Approach 2:
The invention merges the functions of the printed circuit board, mounting structure, and sealing housing into a single integrated resin package. The resin package simultaneously provides mechanical support, electrical connection substrate, and protective enclosure, eliminating the need for separate thick PCB components and achieving both thinness and reliability.
2Length of moving object
If only optically transmissive resin is used to seal the light emitting diode element, then the device thickness is reduced, but light extraction efficiency decreases due to light penetration downward
Solution Approach 1:
The invention applies local quality by using different resin materials with different optical properties in different regions of the resin package. The upper sealing resin is optically transmissive to allow light extraction, while the lower sealing resin is light-blocking to prevent downward light penetration. This localized differentiation maintains thinness while improving light extraction efficiency.
Solution Approach 2:
The invention uses composite materials by combining optically transmissive resin and light-blocking resin in a multi-layer sealing structure. This composite approach allows the device to simultaneously achieve thin profile (through transmissive resin) and high light extraction efficiency (through light-blocking resin preventing downward leakage).
3Loss of energy
If a conical metallic film is used to reflect light and improve extraction efficiency, then light extraction efficiency improves, but the device becomes prone to breakage during substrate removal leading to decreased yield
Solution Approach 1:
The invention replaces the fragile conical metallic film with a more robust resin-based light-blocking structure that can withstand manufacturing processes. The resin package serves as a disposable protective structure that maintains its integrity throughout manufacturing and device operation, eliminating the yield loss associated with metallic film breakage while maintaining light extraction efficiency.
4Device complexity
If only optically transmissive resin is used for sealing, then the device structure is simple and thin, but contrast is low in display applications due to light leakage
Solution Approach 1:
The invention applies local quality by implementing light-blocking properties specifically in the lower region of the sealing structure where contrast is critical for display applications. This localized light blocking prevents unwanted light leakage that would reduce contrast, while maintaining structural simplicity and thinness through the integrated resin package design.
Solution Approach 2:
The invention uses composite materials by combining optically transmissive and light-blocking resins in a multi-layer sealing structure. This composite approach maintains relative structural simplicity while significantly improving display contrast by preventing light leakage in critical regions.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~3
AI summary
A light emitting device includes a base body forming a recess defined by a bottom surface and a side wall thereof, a conductive member whose upper surface being exposed in the recess and whose lower surface forming an outer surface, a protruding portion disposed in the recess, a light emitting element mounted in the recess and electrically connected to the conductive member, and a sealing member disposed in the recess to cover the light emitting element. The base body has a bottom portion and a side wall portion integrally formed of a resin, an inner surface of the side wall portion is the side wall defining the recess and has a curved portion, and the protruding portion is disposed in close vicinity to the curved surface. With this arrangement, a thin and small-sized light emitting device excellent in light extraction efficiency and reliability can be obtained.