Reflective Mounting Substrates for Flip-Chip Horizontal LEDs
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Solution Overview
Problem
Conventional semiconductor light emitting devices face challenges in achieving high brightness with low angular variation in Correlated Color Temperature (CCT) due to the use of large phosphor particles, which often result in high angular variation and require more red phosphor, increasing costs.
Innovation Solution
The implementation of a conformal phosphor layer with large phosphor particles on the outer face and oblique sidewall of LEDs, combined with a reflective filler material in the gap and a lens configuration that maximizes light reflection and efficiency, reduces CCT variation and allows for a higher ratio of yellow to red phosphor, lowering costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If large phosphor particles are used to achieve high brightness, then brightness is improved, but angular variation in CCT increases
Solution Approach 1:
The patent applies local quality by creating a conformal phosphor layer that uniformly coats the oblique sidewall and outer face of the LED. This conformal coating ensures consistent phosphor distribution and particle size throughout the light extraction path, reducing angular variation in CCT while maintaining high brightness through optimized phosphor placement on surfaces with different orientations.
2Stability of the object's composition
If more red phosphor is used to compensate for angular variation, then CCT stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the geometric parameters of the LED structure by introducing oblique sidewalls with specific angles. This geometric modification alters the light extraction and phosphor interaction characteristics, achieving CCT stability through structural design rather than increasing red phosphor concentration, thereby reducing manufacturing costs while maintaining color temperature consistency.
3Productivity
If a reflective layer is added to maximize light reflection, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent merges the reflective function with the existing LED package structure by integrating the reflective layer into the package substrate or housing. This consolidation achieves enhanced light extraction efficiency by redirecting downward-emitted light toward the lens without adding separate, complex reflective components, thereby improving productivity while minimizing increases in device complexity.
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 approach achieves high brightness with low angular variation in CCT, reduces the need for expensive red phosphor, and enhances light extraction efficiency, leading to cost-effective and efficient LED performance.
Implementation Method 1
The reflective layer extends on the mounting substrate to cover substantially all of the mounting substrate that lies beneath the lens, excluding the gap
Implementation Method 2
the LED may incorporate wavelength conversion material such as phosphor
Data Source
Figure 1
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Figure 3A~3C
AI summary
A light emitting device includes a mounting substrate having a reflective layer that defines spaced apart anode and cathode pads, and a gap between them. A light emitting diode die is flip-chip mounted on the mounting substrate, such that the anode contact of the LED die is bonded to the anode pad and the cathode contact of the LED die is bonded to the cathode pad. A lens extends from the mounting substrate to surround the LED die. The reflective layer extends on the mounting substrate to cover substantially all of the mounting substrate that lies beneath the lens, excluding the gap, and may also extend beyond the lens.