Low Z-Height LED Array Package With TSV Support Structure
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Solution Overview
Problem
Existing solutions for densely packed light-emitting diodes (LEDs) face challenges in providing reliable interconnections and adequate heat removal, particularly when each LED must be separately addressable, often requiring expensive materials and complex processing, and are prone to failure due to thermal expansion issues between ceramic and organic materials.
Innovation Solution
A packaging structure for light emitter pixel arrays using an inorganic substrate with through silicon vias (TSV) and a redistribution layer, which includes a top and bottom redistribution layer with copper posts for electrical connection, and a light confinement structure with phosphor and diffuser materials, allowing for dense interconnects and effective thermal transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If individual LEDs are mounted on ceramic substrate with extensive fan-in/fan-out structures and vias, then separate addressability of each LED is achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent transitions from planar fan-in/fan-out routing to three-dimensional vertical interconnection through TSVs. Electrical connections are routed vertically through the substrate thickness rather than spreading laterally, enabling dense pixel arrays with simplified interconnect architecture.
Solution Approach 2:
The invention changes the interconnection topology from two-dimensional surface routing to three-dimensional volumetric routing. This parameter change in spatial dimensionality allows each pixel to be independently addressed through vertical TSV pathways without requiring extensive lateral trace networks.
2Reliability
If ceramic substrate is used for LED mounting, then mechanical support and electrical interconnection are provided, but thermal expansion mismatch causes trace interconnect failure
Solution Approach 1:
The patent employs a homogeneous silicon substrate for both mechanical support and electrical interconnection, eliminating the CTE mismatch problem between dissimilar materials. The silicon substrate provides unified thermal and mechanical properties throughout the device structure.
Solution Approach 2:
The invention uses composite material architecture where silicon substrate integrates multiple functions (mechanical support, electrical interconnection, thermal management) that were previously distributed across multiple materials (ceramic substrate, organic PCB, underfill). This material integration eliminates interfacial thermal expansion mismatches.
3Productivity
If densely packed LED arrays are formed, then light emission density increases, but heat removal becomes difficult
Solution Approach 1:
The silicon substrate acts as an intermediary thermal management component, providing direct thermal pathways from the LED active regions to heat sinks. The high thermal conductivity of silicon enables efficient heat evacuation from densely packed pixels without requiring complex thermal interface structures.
4Ease of operation
If small electrical traces and extensive fan-in structures are used for addressable pixels, then each LED can be separately controlled, but manufacturing cost and processing complexity increase
Solution Approach 1:
The patent employs three-dimensional vertical interconnection through TSVs to replace two-dimensional lateral routing. This dimensional transition reduces the total trace length and interconnect complexity, thereby lowering manufacturing cost and processing requirements while maintaining full pixel addressability.
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 solution enables reliable, dense electrical connections and efficient heat management, allowing for separately addressable LEDs with improved thermal transfer characteristics, reducing the risk of thermal expansion-related failures and enabling thin, non-bulky lighting modules suitable for adaptive lighting applications.
Implementation Method 1
at least one through silicon via containing an electrical conductor is defined to pass through the inorganic substrate and support an electrical connection with the top redistribution layer
Implementation Method 2
An inorganic substrate having a top redistribution layer is attached to the plurality of pixels... allowing for dense interconnects and effective thermal transfer
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A packaging structure for a light emitter pixel array includes a plurality of pixels, with at least some pixels laterally separated from each other with a pixel light confinement structure. An inorganic substrate having a top redistribution layer is attached to the plurality of pixels and at least one through silicon via containing an electrical conductor is defined to pass through the inorganic substrate and support an electrical connection with the top redistribution layer.