Dual Adhesive LED Package for Thermal Conductivity Control
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Solution Overview
Problem
The use of transparent/non-conductive glue in LED packages for mid- or high-power applications is hindered by inconsistent thermal conductivity due to uncontrollable Bond Line Thickness (BLT), leading to increased chances of LED failure from inadequate heat dissipation.
Innovation Solution
Employing two discrete types of non-conductive adhesives, where a UV-curable adhesive controls the precise distance between the LED and the bonding pad, and a UV-stable, thermally conductive adhesive ensures enhanced heat management, allowing for consistent and reliable thermal conductivity even in high-power applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transparent/non-conductive glue is used to attach LED dice to bonding pad, then ease of manufacture and handling is improved, but thermal conductivity becomes inconsistent and unreliable
Solution Approach 1:
The patent changes the viscosity parameter of the transparent adhesive by formulating it with specific resin components and additives to achieve optimal thickness control. This allows the adhesive to maintain proper gap thickness (1-5 micrometers) without displacing the LED dice, thereby ensuring consistent thermal conductivity while preserving ease of manufacture
Solution Approach 2:
The patent uses a composite adhesive formulation combining transparent non-conductive adhesive with specific viscosity-modifying agents and thermal conductive fillers. This composite material achieves both the desired transparency for brightness and improved thermal conductivity consistency, resolving the reliability issue while maintaining ease of handling
2Temperature
If gap thickness is reduced to less than 1 um to improve thermal conductivity, then heat dissipation is improved, but manufacturing precision becomes difficult to control
Solution Approach 1:
The patent optimizes the viscosity parameter of the transparent adhesive to a specific range that prevents excessive flow during bonding. This parameter change allows the adhesive to self-regulate the gap thickness to an optimal range of 1-5 micrometers, achieving sufficient heat dissipation while maintaining controllable manufacturing precision
Solution Approach 2:
The patent accepts a slightly larger gap thickness (1-5 um rather than <1 um) as a trade-off for using a low-viscosity transparent adhesive that is easy to apply. This approach prioritizes manufacturing feasibility over maximum theoretical thermal conductivity, achieving practical heat dissipation sufficient for mid-power applications
3Ease of operation
If low viscosity transparent adhesive is used to improve ease of operation, then applicability is improved, but LED dice displacement increases before glue setting
Solution Approach 1:
The patent carefully balances the viscosity parameter of the transparent adhesive - not too low to cause excessive dice displacement, not too high to compromise applicability. The optimized viscosity range enables easy application while providing sufficient resistance to prevent LED dice displacement during the curing process
Solution Approach 2:
The patent incorporates preliminary positioning features and optimized adhesive formulation that maintains stability during the critical period before UV curing. The adhesive is designed to have adequate green strength immediately upon application to hold the LED dice in position, preventing displacement before the adhesive sets
4Illumination intensity
If transparent/non-conductive glue is used for mid- or high-power products, then brightness is improved, but thermal conductivity insufficiency increases failure risk
Solution Approach 1:
The patent formulates a composite transparent adhesive that combines non-conductive transparent base material with thermally conductive fillers. This composite maintains the brightness advantages of transparent adhesive while improving thermal conductivity sufficient for mid-power applications, thereby reducing LED failure risk
Solution Approach 2:
The patent optimizes the gap thickness parameter to a controlled range of 1-5 micrometers using viscosity-modified adhesive. This parameter control ensures consistent thermal pathways for heat dissipation, reducing the risk of thermal runaway and LED failure in mid-power applications while preserving the brightness benefits
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 approach enables the production of reliable LED packages with controlled thermal conductivity, reducing the risk of LED failure by maintaining a consistent gap thickness and effectively managing heat generated by high-power LEDs.
Implementation Method 1
a first discrete amount of a first type of adhesive is provided on a first surface of the bonding pad, wherein the first type of adhesive comprises a UV-curable adhesive
Implementation Method 2
a second discrete amount of a second type of adhesive is provided on the first surface of the bonding pad to achieve a second intermediate package, wherein the second type of adhesive comprises a UV-stable, thermally conductive adhesive
Data Source
AI summary
A package for a light source, a semiconductor device, and methods of manufacturing the same are disclosed. In particular, a Light Emitting Diode (LED) dice is attached to a bonding pad of the light source package by two discrete types of different adhesives. One of the adhesives may be curable under exposure to Ultraviolet (UV) light and the other adhesive may be cured under thermal radiation, but is stable when exposed to UV light.