Chip-Scale LED with Reflective Ceramic Substrate
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Solution Overview
Problem
Current chip-scale packaged LED devices face challenges in achieving high brightness, miniaturization, and reliability, particularly in terms of light extraction efficiency, view angle, and manufacturing complexity.
Innovation Solution
The design incorporates a substrate with a reflective ceramic material, flip-chip LED dies with optimized electrode configurations, an electrical conductive structure, a lens structure, an insulation layer, and a reflection layer, along with specific dimensions and arrangements to enhance light extraction efficiency, prevent moisture ingress, and simplify the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If chip-scale packaging is used for miniaturization, then volume is reduced, but brightness and light extraction efficiency deteriorate
Solution Approach 1:
The packaging structure is divided into multiple functional layers including substrate, reflective layer, lens structure, and encapsulant, each optimized for specific functions. The LED chip is segmented into p-type and n-type regions with separate bonding pads for optimized electrical connection
Solution Approach 2:
The patent transitions from planar packaging to three-dimensional vertical stacking, with the lens structure extending upward from the chip surface and the substrate providing vertical support, enabling better light extraction in the vertical dimension while maintaining small footprint
2Reliability
If complex bonding structures are used to improve reliability, then connection strength is enhanced, but manufacturing complexity increases
Solution Approach 1:
Multiple functions are merged into single components: the substrate serves as both mechanical support and electrical connection carrier, the reflective layer combines optical reflection with electrical isolation, and the lens structure integrates light extraction with protective encapsulation
Solution Approach 2:
The substrate performs multiple roles simultaneously: mechanical support for the chip, electrical connection pathway, thermal management interface, and structural anchor for the lens structure. The bonding pads serve both electrical connection and mechanical alignment functions
3Power
If larger bonding pads are used to improve electrical connection, then conductivity is enhanced, but device area increases
Solution Approach 1:
The bonding pads are designed with non-uniform dimensions optimized for their specific functions: the first bonding pad (n-type) has different dimensions than the second bonding pad (p-type), with each sized appropriately for its current carrying requirements and alignment needs
Solution Approach 2:
Electrical connection is optimized by utilizing the vertical dimension through multi-layer substrate design and through-substrate vias, allowing adequate conductivity without increasing the planar footprint of the bonding pads
4Illumination intensity
If reflective materials are added to improve light extraction, then brightness is enhanced, but manufacturing steps increase
Solution Approach 1:
The reflective layer is integrated with the substrate structure, forming a single combined component that provides both mechanical support and optical reflection functions, eliminating the need for separate reflective coating steps
Solution Approach 2:
The substrate is constructed as a composite structure combining materials with different properties: a base material providing mechanical strength and a reflective layer (such as aluminum or silver) providing optical reflection, creating a multi-functional integrated component
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 solution results in a miniaturized LED device with improved brightness, reliability, and light extraction efficiency, while simplifying the manufacturing process and preventing moisture-related degradation.
Implementation Method 1
a substrate with a reflective ceramic material
Implementation Method 2
a lens structure
Data Source
AI summary
An LED device includes a substrate, a number (N) of flip-chip LED die(s), an electrical conductive structure and a lens structure. The substrate has upper and lower surfaces and is formed with multiple through holes. A ratio of LED die(s) surface area to an area of the upper surface of the substrate ranges from 22.7% to 76.2%. The electrical conductive structure includes a number (N) of upper bonding pad assembly (assemblies), a number (N+1) of lower bonding pads and a number (2N) of interconnectors. Each upper bonding pad assembly includes two upper bonding pads electrically connected to the LED die(s). The interconnectors are disposed in the through holes and interconnect the upper and lower bonding pads. The lens structure covers the LED die(s).