Low-Temperature Brazed Heatsink for Aluminum-Copper Cooling Joints
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Solution Overview
Problem
Existing methods for manufacturing heat sinks for power electronics components face challenges such as high manufacturing costs, material distortion due to high brazing temperatures, and the inability to join aluminum and copper effectively without forming a low-melting-point aluminum-copper phase, which can lead to component melting.
Innovation Solution
A brazing process using a low-melting-point brazing alloy between 520°C and 540°C is employed to join at least two components of the heat sink, preventing the formation of an undesirable aluminum-copper phase, allowing for the use of a soft soldering process to fix power electronics components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical fastening or adhesive bonding is used to attach the heat dissipation fin array to the heat source component, then the assembly is easier to manufacture, but the thermal contact resistance increases and reliability deteriorates under thermal cycling
Solution Approach 1:
The patent changes the bonding mechanism from mechanical/adhesive to metallurgical bonding through brazing. By controlling the brazing temperature (above the melting point of the filler metal but below the base metals) and atmosphere (inert or vacuum), it achieves a phase change in the filler metal that enables strong, low-resistance thermal contact that withstands thermal cycling without degradation.
Solution Approach 2:
The patent uses a composite bonding approach by introducing a filler metal (brazing alloy) that is distinct from both the heat source component and heat dissipation fins. This filler metal creates an intermediate layer that facilitates metallurgical bonding while maintaining low thermal contact resistance, effectively combining the advantages of both mechanical strength and thermal conductivity.
2Reliability
If brazing is used to attach the heat dissipation fin array to the heat source component, then thermal contact resistance decreases and reliability improves, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by pre-coating the heat source component and heat dissipation fins with brazing material or applying the filler metal beforehand. This preparation ensures that when brazing occurs, the filler metal is already in position to create uniform, reliable joints, reducing the complexity of the actual brazing process and ensuring consistent results.
Solution Approach 2:
The filler metal acts as an intermediary substance that facilitates the bonding between the heat source component and heat dissipation fins. This intermediate layer enables metallurgical bonding without requiring direct contact between dissimilar metals, simplifying the brazing process while achieving reliable, low-resistance thermal contact that withstands thermal cycling.
3Reliability
If conventional brazing processes are used, then thermal contact resistance is reduced, but void formation occurs and manufacturing precision deteriorates
Solution Approach 1:
The patent employs an inert atmosphere (such as nitrogen or argon) or vacuum environment during the brazing process to prevent oxidation and unwanted reactions. This controlled environment ensures uniform filler metal flow and prevents void formation, achieving both low thermal contact resistance and high manufacturing precision with consistent, void-free joints.
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 method prevents component melting and distortion, reduces thermal stress, and improves manufacturing accuracy while maintaining effective thermal performance and copper surface area flexibility without altering the manufacturing process.
Implementation Method 1
The brazing step comprises heating the heat source component and the heat dissipation fin array, which are held in a fixed relative position to one another, to a temperature above the melting point of the filler metal
Implementation Method 2
heating the heat source component and the heat dissipation fin array to a temperature above the melting point of the filler metal
Implementation Method 3
heat source component and to the heat dissipation fin array through a brazing step
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a method for producing a heatsink (3) for the liquid cooling of power electronics devices (2), wherein the heatsink (3) comprises at least two components, selected from an aluminium lower part (30), an aluminium upper part (31), an aluminium insert part (32) and a copper plate (7), wherein at least two components are connected by means of a brazing process using a low-melting braze, wherein the brazing process is carried out at a temperature between 520°C and 540°C in order to form a low-melting brazed connection (4) between the at least two components.