Cold Spray Aluminum on Ceramic Substrates
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Solution Overview
Problem
Current methods for producing ceramic circuit boards with aluminum or aluminum alloys as circuit materials are costly and inefficient, particularly the molten metal method and brazing method, which require complex facilities and high-temperature pressurization, and struggle with adhesion to ceramic substrates.
Innovation Solution
A method involving the cold spray technique, where aluminum or aluminum alloy powder is accelerated to 250-1050 m/s and heated to 10-270°C, then deposited onto a ceramic substrate in an inert gas atmosphere, followed by heat treatment at 400-600°C to form a metal layer with high adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper is used as circuit material on highly thermal conductive ceramic substrate, then thermal conductivity is improved, but crack resistance under thermal cycles deteriorates
Solution Approach 1:
The invention changes the material parameter from copper to aluminum or aluminum alloy, which has different physical properties including lower yield strength but better thermal cycle resistance. This parameter change resolves the contradiction by selecting a material that maintains adequate thermal conductivity while significantly improving crack resistance under thermal cycling conditions.
Solution Approach 2:
The invention uses aluminum alloy instead of pure copper, creating a composite material solution that balances thermal conductivity and mechanical durability. The alloying elements in the aluminum alloy provide enhanced properties that resolve the contradiction between thermal performance and thermal cycle resistance.
2Strength
If molten metal method is used to form aluminum circuit, then adhesion to ceramic substrate is improved, but facility complexity and cost increase
Solution Approach 1:
The invention replaces the complex molten metal deposition system with a simpler cold spray technique. Instead of using molten aluminum requiring sophisticated heating and control facilities, the invention uses accelerated aluminum particles in solid or semi-solid state, substituting a complex thermal-mechanical system with a simpler kinetic spray system that achieves comparable adhesion.
Solution Approach 2:
The invention changes the temperature parameter from high (molten state) to low (cold spray state), forming aluminum circuit at room temperature or slightly elevated temperatures. This parameter change eliminates the need for complex high-temperature facilities while maintaining adhesion through kinetic energy of accelerated particles.
3Strength
If brazing method is used to form aluminum circuit, then adhesion to ceramic substrate is improved, but productivity deteriorates due to high temperature pressurization
Solution Approach 1:
The invention replaces the brazing process requiring high-temperature furnaces and pressurization equipment with a cold spray technique. This substitution eliminates time-consuming heating and pressurization cycles, enabling faster production while achieving equivalent or superior adhesion through particle kinetic energy and subsequent heat treatment.
Solution Approach 2:
The invention skips the lengthy high-temperature brazing process by using cold spray deposition followed by brief heat treatment. This rushing through the essential bonding step without unnecessary prolonged heating and pressurization significantly improves productivity while maintaining adhesion quality.
4Strength
If aluminum powder is sprayed at high velocity and heated, then adhesion to ceramic substrate is improved, but energy consumption increases
Solution Approach 1:
The invention uses partial heating of aluminum powder to a moderate temperature range (10-270°C) rather than complete melting. This partial thermal action, combined with high-velocity kinetic energy, achieves sufficient adhesion while consuming less energy than full molten metal processes or prolonged high-temperature brazing.
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 efficiently produces ceramic circuit boards with high adhesion using a simple facility, eliminating the need for molten aluminum and brazing, and allows for pattern formation without etching, while maintaining thermal and electrical properties.
Implementation Method 1
accelerating metal powder to a velocity of from 250 to 1050 m/s
Implementation Method 2
heating the metal powder to from 10°C to 270°C
Implementation Method 3
subjecting the ceramic substrate and the metal layer formed on the ceramic substrate to a heat treatment in an inert gas atmosphere. The ceramic substrate and the metal layer are heated to from 400°C to 600°C
Data Source
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AI summary
Disclosed is a method for producing a ceramic circuit board including a ceramic substrate and a metal layer formed on the ceramic substrate. This method includes a step of forming the metal layer on the ceramic substrate by spraying a metal powder after accelerating the metal powder to a velocity of from 250 to 1050 m/s as well as heating the metal powder to from 10°C to 270°C and a step of subjecting the ceramic substrate and the metal layer to a heat treatment in an inert gas atmosphere.