Nano-twinned Copper Foil Bonding for High-Power Thermal Management
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Solution Overview
Problem
Current bonding layers and thermal interface materials face challenges such as high temperature instability, reliability issues due to intermetallic compounds, increased thermal resistance, and high costs, as well as low thermal conductivity and mismatched thermal expansion coefficients, which hinder effective heat dissipation in high-power electronic components.
Innovation Solution
A nano-twinned copper foil with 80% or more of its surfaces exposing (111) planes and low roughness is developed, allowing for efficient bonding at low temperatures and short times with improved mechanical strength and electrical properties, reducing electrical and thermal resistance, and enabling applications in high-power components and thermal interface materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder is used as bonding layer material, then bonding can be achieved, but reliability problems occur due to intermetallic compounds and high temperature instability
Solution Approach 1:
The invention changes the crystallographic parameters of copper by creating a nano-twinned structure with (111) preferred orientation. This parameter change in crystal structure results in a bonding layer that maintains stability at high temperatures (300°C and above) while avoiding the intermetallic compound formation issues associated with traditional solder materials.
Solution Approach 2:
The invention creates a composite microstructure within the copper bonding layer by introducing nanoscale twins with specific (111) orientation. This composite structure at the micro-scale provides both the mechanical properties needed for bonding and the thermal stability required for high-power applications, eliminating the need for separate solder and copper layers.
2Reliability
If sintered copper or silver is used as bonding layer, then thermal conductivity is improved, but thermal resistance increases due to porous structure and manufacturing cost increases
Solution Approach 1:
The invention changes the density parameter by creating a fully dense nano-twinned copper structure without pores or voids. This dense structure eliminates the thermal resistance issues inherent in sintered materials while maintaining the high thermal conductivity of copper, achieving both excellent heat dissipation and smooth bonding surfaces.
3Temperature
If polymer is used as bonding layer, then low temperature bonding is achieved, but thermal conductivity decreases by 2 orders of magnitude
Solution Approach 1:
The invention changes the thermal conductivity parameter by introducing nanoscale twins with (111) orientation in copper, which creates a structure that facilitates phonon transport. This results in a polymer-free bonding layer that maintains metal-level thermal conductivity while enabling low-temperature bonding processes.
4Reliability
If traditional bonding methods are used, then bonding is achieved, but heat dissipation coefficient is low and thermal expansion mismatch occurs
Solution Approach 1:
The invention applies homogeneity by using copper throughout the bonding layer with consistent nano-twinned (111) orientation. This homogeneous copper structure matches the thermal expansion coefficient of copper substrates (eliminating mismatch issues) while maintaining high thermal conductivity for effective heat dissipation.
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 nano-twinned copper foil provides excellent bonding quality with minimal gaps and reduced thermal resistance, enhancing the reliability and efficiency of heat dissipation in electronic components, while maintaining low processing costs and temperatures.
Implementation Method 1
using the property of high diffusion rate of the (111) plane, two substrates at low temperature and/or in a short time
Data Source
AI summary
A nano-twinned copper foil is provided, which comprises: plural twinned grains, wherein at least part of the plural twinned grains are formed by stacking plural nano-twins along a [111] crystal axis. The nano-twinned copper foil has a first surface and a second surface opposite to the first surface, and 80% or more of areas of the first surface and the second surface respectively exposes (111) planes of the nano-twins. In addition, the present invention further provides a method for manufacturing the aforesaid nano-twinned copper foil, an electronic element comprising the same, and a method for manufacturing the electronic element.