Die Attach Adhesive Thermal Conductivity via Surface-Modified Fillers
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Solution Overview
Problem
Conventional die attach adhesives for high-brightness LEDs face challenges with thermal conductivity, mechanical stability, and ease of use, particularly in high-power devices where existing materials fail to meet demands for thermal management and stability, and have limitations in shelf life and curing temperatures.
Innovation Solution
A one-part die attach adhesive with high thermal and electrical conductivity, achieved through a composition of 30-96% thermal conductive filler, 2-30% polymer matrix, and 2-40% solvent, using surface-modified fillers like silver, copper, or nickel, and a dispersing agent, which enhances thermal conductivity and stability while allowing low-temperature curing and extended shelf life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional epoxy adhesives are used as die attach adhesive, then the adhesive provides good adhesion and ease of use, but the thermal conductivity is low (1-5 W/M·K) which cannot meet the thermal management demands of high-power LEDs
Solution Approach 1:
The patent uses composite materials by combining epoxy adhesive matrix with high thermal conductivity fillers (silver, copper, aluminum, boron nitride, aluminum nitride, and carbon allotropes) to create a die attach adhesive with enhanced thermal conductivity exceeding 5 W/M·K while maintaining adhesion properties
Solution Approach 2:
The patent changes the thermal conductivity parameter of the adhesive by optimizing filler concentration, particle size distribution, and filler morphology to achieve maximum heat dissipation efficiency while maintaining mechanical bonding strength
2Reliability
If high concentration of thermal conductive fillers is added to improve thermal conductivity, then the thermal conductivity increases, but the adhesion strength and mechanical stability of the adhesive decrease
Solution Approach 1:
The patent applies local quality by using different filler sizes (micro and nano particles) and distributions within the adhesive matrix, creating optimal local regions for both thermal conduction and mechanical bonding strength
Solution Approach 2:
The patent optimizes the concentration, size distribution, and morphology parameters of fillers to achieve a balance between thermal conductivity and adhesion strength, preventing filler aggregation that would compromise mechanical properties
3Strength
If conventional curing processes are used for epoxy adhesives, then the adhesive provides good mechanical properties, but the curing temperature is high which can damage LED components and increases energy consumption
Solution Approach 1:
The patent modifies the curing parameters by using modified epoxy resin systems with lower glass transition temperatures and optimized cross-linking densities, enabling effective curing at reduced temperatures that protect LED components while maintaining mechanical strength
4Reliability
If high thermal conductivity fillers are used to improve heat dissipation, then the thermal management performance increases, but the adhesive becomes more sensitive to moisture and environmental degradation
Solution Approach 1:
The patent creates a composite adhesive system combining hydrophobic epoxy matrix with hydrophilic filler particles, using surface treatments and coupling agents to establish moisture barriers that protect the filler-matrix interface from environmental degradation
Solution Approach 2:
The patent uses coupling agents and surface treatments as intermediary layers between hydrophilic fillers and the epoxy matrix, creating moisture-resistant interfaces that maintain thermal conductivity while preventing moisture ingress and degradation
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 provides thermal conductivity of ≥40 W/M·K, excellent curability at ≤100°C, and high stability at ≥−10°C, addressing the limitations of existing adhesives by forming a continuous heat transmission pathway and improving bond strength and shelf life, making it suitable for high-brightness LED packaging.
Implementation Method 1
The thermal conductivity of a conventional die attach adhesive (DAA) is mostly achieved by the fillers and the linkage between the fillers through the epoxy resin matrix
Implementation Method 2
Epoxy adhesives are most commonly used in HB-LEDs and in semiconductor packaging because of their good adhesion to different kinds of substrates
Implementation Method 3
U.S. patent application Ser. No. 10/426,485 discloses the use of non-electrically conductive nanoparticles in a polymer matrix to improve the thermal conductivity of a polymer composite system
Implementation Method 4
Epoxy adhesives are most commonly used in HB-LEDs and in semiconductor packaging because of their good adhesion to different kinds of substrates
Data Source
AI summary
The present invention relates to a composition for a one-part die attach adhesives material useful for packaging semi-conductors including HB-LED. The composition of the present invention includes a thermal and electrical conductive filler, a polymer matrix and a solvent which form a material with high thermal conductivity, low curing temperature and high self-life temperature. The present invention also relates to a method of preparing said composition by mixing a size-selected and surface-modified filler formulation, a polymer matrix and a non-reactive organic solvent together followed by curing the mixture at a low temperature.