Semiconductor Light Emitting Device Heat Dissipation
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Solution Overview
Problem
Conventional semiconductor light emitting devices face challenges in miniaturization and high luminance due to heat dissipation issues, as the sub mount substrate interferes with heat transfer from the active layer to the lead, reducing light emission efficiency.
Innovation Solution
The semiconductor light emitting device incorporates a ceramic base member with anode and cathode through wirings that facilitate heat dissipation by connecting the LED chips directly to the base member, and uses a reflective resin with an inclined reflective surface to enhance light reflection without increasing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sub mount substrate is used to support the semiconductor layer, then the LED chip can be mounted on the lead, but heat dissipation is prevented because the sub mount substrate is interposed between the active layer and the lead
Solution Approach 1:
The invention removes the sub mount substrate from between the active layer and the lead, extracting the heat dissipation pathway obstruction. The semiconductor layer is mounted directly on the lead, allowing heat to be efficiently transferred from the active layer through the lead to the base member, while the lead still provides structural support for mounting.
Solution Approach 2:
The lead is given multiple functions: it serves as both the structural support for mounting the semiconductor layer and as the heat dissipation pathway. By eliminating the sub mount substrate, the lead becomes a multi-functional component that simultaneously provides mechanical support and thermal conduction, resolving the contradiction between structural integrity and heat dissipation.
2Illumination intensity
If the inner wall surface of the reflector is greatly inclined to reflect light upward, then luminance is improved, but the device size is enlarged
Solution Approach 1:
The invention changes the reflector geometry from a conventional inclined surface to a compound parabolic concentrator (CPC) shape, which utilizes three-dimensional geometric optimization. The CPC shape with specific curvature parameters (R1, R2, R3, R4) allows light reflection and concentration in multiple spatial dimensions, achieving high luminance while maintaining a compact form factor that does not excessively enlarge the device.
Solution Approach 2:
The reflector's geometric parameters (radii of curvature R1-R4, inclination angles, and profile shape) are optimized to achieve the desired light reflection characteristics. By carefully controlling these parameters, the reflector can effectively direct light upward while keeping the horizontal and vertical dimensions of the device within acceptable limits, thus resolving the size-luminance trade-off.
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 design improves heat dissipation and light emission efficiency while enabling miniaturization and high luminance, as heat is effectively transferred through the ceramic base member and light is efficiently reflected without enlarging the device.
Implementation Method 1
heat is mainly generated from the active layer. The heat is dissipated by being transferred to the lead 92 and the base member 91
Implementation Method 2
an inner wall surface of the reflector 905 may be greatly inclined from an angle perpendicular to the substrate 901. However, as the inner wall surface is inclined, the semiconductor light emitting device 900 is enlarged
Data Source
AI summary
A semiconductor light emitting device includes an LED chip, which includes an n-type semiconductor layer, active layer, and p-type semiconductor layer stacked on a substrate. The LED chip further includes an anode electrode connected to the p-type semiconductor, and a cathode connected to the n-type semiconductor. The anode and cathode electrodes face a case with the LED chip mounted thereon. The case includes a base member including front and rear surfaces, and wirings including a front surface layer having anode and cathode pads formed at the front surface, a rear surface layer having anode and cathode mounting electrodes formed at the rear surface, an anode through wiring connecting the anode pad and the anode mounting electrode and passing through a portion of the base member, and a cathode through wirings connecting the cathode pad and the cathode mounting electrode and passing through a portion of the base member.