Metal Reflecting Layer Replaces DBR in Flip Chip LED Packages
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Solution Overview
Problem
Conventional light emitting device packages with flip chip bonding structures using distributed Bragg reflectors (DBR) face challenges such as complex manufacturing processes, sensitivity to particles, uneven step coverage, long manufacturing times, and potential cracking or peeling due to thermal stress, as well as vulnerability to high electric fields.
Innovation Solution
A light emitting device package incorporating a metal reflecting layer with specific segments and insulating layers, which serves as a field plate and improves heat dissipation, replacing the DBR to enhance luminous flux, manufacturing efficiency, and durability by using a metal reflecting layer with good step coverage and electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a distributed Bragg reflector (DBR) is used to reflect light in a flip chip bonding structure, then light reflection is achieved, but the manufacturing process becomes complex and time-consuming with sensitivity to particles and uneven step coverage
Solution Approach 1:
The patent replaces the complex DBR structure with a simpler metal reflecting layer that replicates the light reflection function. The metal layer is deposited using conventional techniques without the need for precise thickness control or cleanroom conditions required for DBR, thus simplifying manufacturing while maintaining optical performance.
Solution Approach 2:
The patent uses a metal reflecting layer that can be deposited as a thin, inexpensive layer without requiring the precise engineering and quality control of DBR structures. This approach accepts a simpler, more manufacturable solution that achieves the same functional outcome with less complexity.
2Illumination intensity
If a distributed Bragg reflector (DBR) is used to reflect light, then light reflection is achieved, but manufacturing time increases and productivity decreases
Solution Approach 1:
The metal reflecting layer replicates the DBR's light reflection function through a single deposition step, eliminating the multiple alternating layer deposition and precise thickness control required for DBR. This dramatically reduces manufacturing time and increases production throughput.
3Illumination intensity
If a DBR is used in the light emitting device package, then light reflection is achieved, but cracking or peeling occurs due to thermal stress
Solution Approach 1:
The patent changes the material parameter from multi-layer dielectric DBR to a single-layer metal reflecting layer. The metal layer has different thermal expansion properties and mechanical strength that prevent the cracking and peeling issues observed in DBR structures under thermal stress, while maintaining the light reflection function.
4Illumination intensity
If a DBR is used to reflect light, then light reflection is achieved, but the structure becomes vulnerable to high electric fields
Solution Approach 1:
The metal reflecting layer replicates the optical function of DBR while providing inherent electrical robustness. The metal material naturally withstands high electric fields without breakdown, unlike the dielectric layers in DBR that are susceptible to electrical stress and failure.
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 metal reflecting layer improves luminous flux, reduces manufacturing complexity and time, minimizes cracking and peeling, and protects against high electric fields while enhancing heat release characteristics, offering a more reliable and efficient alternative to DBR-based solutions.
Implementation Method 1
a metal reflecting layer disposed under the light emitting structure
Implementation Method 2
the metal reflecting layer includes: a first segment overlapped with the second electrode in a thickness direction of the light emitting structure
Implementation Method 3
have a short period for a manufacturing process thereof, and has minimal or no cracking or peeling
Data Source
AI summary
A light emitting device includes a substrate; a light emitting structure disposed on the substrate; a first insulation layer disposed on the light emitting structure; a second insulation layer disposed on the first insulation layer; a first electrode and a second electrode electrically connected to the light emitting structure; a first pad electrically connected to the first electrode; and a second pad electrically connected to the second electrode.