LED Flip-Chip Package With Dummy TSVs for Thermal Management
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Solution Overview
Problem
Conventional LED package structures using sapphire substrates face inefficiencies in heat dissipation due to low thermal conductivity, which affects the LED's ability to dissipate heat effectively and optimizes the light output area, as gold wires and electrodes occupy chip space and block light emission.
Innovation Solution
The implementation of a flip-chip package structure with a carrier chip that includes active and dummy through-substrate vias (TSVs) and solder bumps, where active TSVs conduct current and dummy TSVs and solder bumps facilitate heat dissipation without carrying current, allowing for improved thermal management and unobstructed light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sapphire substrate is used for LED package, then LED can be formed on matching substrate, but heat dissipation efficiency deteriorates due to low thermal conductivity
Solution Approach 1:
The patent divides the heat dissipation function from the substrate by introducing separate thermal management components (heat sink, thermal vias) while keeping the sapphire substrate for its primary function of supporting LED formation. This segmentation allows each component to optimize its specific function without compromise.
Solution Approach 2:
The patent introduces thermal vias and heat sink structures as intermediary elements between the LED chip and the external environment. These intermediaries provide efficient thermal conduction paths, mediating the heat transfer from the LED chip through the package structure without requiring the substrate itself to have high thermal conductivity.
2Reliability
If gold wires and electrodes are used to connect LED to lead frame, then electrical connection is achieved, but light output area is reduced due to occupation of chip space
Solution Approach 1:
The patent transitions from planar electrode connections to three-dimensional vertical connections using bump structures. The electrical connections are moved to the vertical dimension through TSVs and solder bumps, allowing the chip surface to be fully utilized for light emission while maintaining robust electrical connectivity through the thickness of the package.
Solution Approach 2:
The bump structures serve multiple functions simultaneously: they provide electrical connection, mechanical bonding, and thermal conduction. This multi-functionality eliminates the need for separate gold wires and electrodes, maximizing the light output area while achieving all necessary connection functions through the bump structures alone.
3Reliability
If all TSVs are made electrically active for current conduction, then electrical connectivity is maximized, but heat dissipation efficiency is reduced because current-carrying TSVs cannot serve dual thermal management function
Solution Approach 1:
The patent segments the TSV population into two distinct groups: active TSVs that carry electrical current and dummy TSVs that are dedicated to thermal conduction. This segmentation allows each subset of TSVs to optimize its specific function without interference, with dummy TSVs providing pure thermal pathways free from electrical current effects.
Solution Approach 2:
The patent applies different functional qualities to different spatial locations within the package. Active TSVs positioned for electrical connection have conductive properties optimized for current flow, while dummy TSVs positioned for thermal management have properties optimized for heat conduction. This local differentiation of quality allows simultaneous optimization of both electrical and thermal performance.
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 enhances heat dissipation and light output efficiency by using thermally conductive dummy TSVs and solder bumps, while maintaining electrical functionality, thus improving the overall performance of LED packages.
Implementation Method 1
dummy TSVs and solder bumps facilitate heat dissipation without carrying current
Implementation Method 2
active TSVs conduct current
Data Source
AI summary
A light-emitting device (LED) package component includes an LED chip having a first active bond pad and a second active bond pad. A carrier chip is bonded onto the LED chip through flip-chip bonding. The carrier chip includes a first active through-substrate via (TSV) and a second active TSV connected to the first and the second active bond pads, respectively. The carrier chip further includes a dummy TSV therein, which is electrically coupled to the first active bond pad, and is configured not to conduct any current when a current flows through the LED chip.