LED Chip Thermal Resistance via Protruding Substrate Structure
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Solution Overview
Problem
In light emitting devices, there is a challenge in reducing thermal resistance between the LED chip and the mounting substrate, and the joining process variability leads to inconsistent thermal resistance, affecting radiation performance and reliability.
Innovation Solution
A light emitting device design featuring a mounting substrate with a protruding structure around the outer periphery of the second electrode, where the LED chip is electrically connected using solder joints that fill the space between the electrode, conductor portion, and protruding structure, reducing thermal resistance and joint thickness variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional joining methods are used to connect LED chip to mounting substrate, then electrical connection is achieved, but thermal resistance between LED chip and mounting substrate is high
Solution Approach 1:
The patent transitions from conventional planar bump bonding to a three-dimensional structure where the conductor portion extends vertically from the mounting substrate surface. This vertical extension creates additional thermal conduction pathways and increases the contact area between the LED chip and mounting substrate, thereby reducing thermal resistance while maintaining electrical connection functionality.
Solution Approach 2:
The protruding structure is pre-formed on the mounting substrate before the LED chip is mounted. This preliminary preparation ensures that when the LED chip is bonded, the thermal and electrical connections are optimally established from the outset, preventing subsequent thermal management issues and ensuring consistent radiation performance.
2Manufacturing precision
If conventional bump joining is used, then electrical connection is established, but joining process variability causes inconsistent thermal resistance
Solution Approach 1:
The protruding structure is pre-formed on the mounting substrate with precise dimensions and positioning before the LED chip mounting process. This preliminary preparation establishes a fixed reference geometry that guides the bonding process, ensuring consistent joint thickness and area across all devices. The pre-formed structure eliminates variability introduced during the joining process, as the conductor portion's height and position are predetermined rather than dependent on bump formation variations.
Solution Approach 2:
The patent changes the geometric parameters of the connection structure by extending the conductor portion vertically from the substrate surface. This dimensional change transforms the joining interface from a simple planar contact to a three-dimensional interface with controlled height and area, thereby improving manufacturing precision and ensuring consistent thermal resistance across production batches.
3Temperature
If thin solder joints are used to reduce thermal resistance, then heat dissipation improves, but joint strength and reliability decrease
Solution Approach 1:
The patent resolves the strength-thermal resistance trade-off by transitioning to a three-dimensional conductor structure. The vertical extension of the conductor portion increases the contact area with the LED chip while maintaining a relatively thin horizontal profile. This dimensional change allows heat dissipation to improve through increased contact area without compromising joint strength, as the extended structure provides both thermal pathways and mechanical anchoring.
Solution Approach 2:
The solder joint is nested within the structure formed by the protruding conductor portion and LED chip electrodes. This nesting configuration allows the solder to fill the space efficiently, creating a strong mechanical bond while the extended conductor portions provide additional thermal conduction pathways. The nested arrangement maximizes the use of limited joint space to achieve both strength 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 design effectively reduces thermal resistance and variability, enhancing radiation performance and reliability by precise management of joint thickness and area, preventing short circuits and improving heat dissipation.
Implementation Method 1
the second electrode and the second conductor portion are joined to each other by a second joint portion formed from solder
Implementation Method 2
the first electrode and the first conductor portion are joined to each other by a first joint portion formed from solder
Data Source
AI summary
Light emitting device includes structure protruding from a side of a surface of second conductive semiconductor layer of LED chip toward a side of a surface of second conductor portion of mounting substrate to contact the surface of second conductor portion, and is positioned to extend around an outer periphery of second electrode. First electrode and a first conductor portion are joined to each other by first joint portion, and second joint portion joining second electrode and second conductor portion to each other fills a space surrounded by second electrode, protruding structure, and second conductor portion. Protruding structure is disposed to extend around the outer periphery of second electrode to surround second joint portion in planar view. A part of mounting substrate overlapping protruding structure in planar view is either identical in height to or lower than a part of second conductor portion joined to second joint portion.