Warm Spraying Aluminum Circuit Boards on Ceramic Substrates
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Solution Overview
Problem
Existing methods for manufacturing aluminum circuit boards on ceramic base materials face challenges such as high facility costs, low productivity, and the need for etching steps, with issues like crack generation and oxidation of aluminum at high temperatures, particularly in molten metal and brazing methods, and inefficiencies in cold spraying due to high power consumption and gas requirements.
Innovation Solution
A warm spraying method is employed, where aluminum or aluminum alloy particles are sprayed onto a ceramic base material at velocities between 450 m/s and 1000 m/s, with temperatures between the softening and melting points, to form a metal layer with high adhesiveness, avoiding the use of molten aluminum and brazing materials, and allowing for the formation of dense, low-resistance metal layers without etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the molten metal method is used to form aluminum circuit on ceramic base material, then the aluminum circuit can be formed, but the facility cost and facility maintenance cost become expensive
Solution Approach 1:
The patent changes the temperature parameter of the aluminum layer from molten state to a lower temperature range (room temperature to below melting point), thereby avoiding the need for expensive molten metal handling facilities while still achieving good adhesion to the ceramic substrate through controlled heating and pressure application
Solution Approach 2:
The patent uses aluminum foil as a temporary, inexpensive material that can be easily applied and removed, replacing the need for expensive molten metal facilities. The aluminum foil serves its purpose during the bonding process and can be discarded or reused without significant cost
2Manufacturing precision
If the brazing method is used to join aluminum foil on ceramic base material, then the aluminum circuit can be formed, but the productivity is not sufficiently high due to high temperature and continuous pressurization requirements
Solution Approach 1:
The patent changes the temperature parameter from high temperature brazing to a lower temperature range that still allows for effective bonding without requiring continuous high-temperature maintenance, thereby reducing processing time and improving productivity
Solution Approach 2:
The patent applies pressure in a periodic manner rather than requiring continuous pressurization throughout the process. Pressure is applied during heating and bonding phases, then reduced or removed, allowing for faster cycle times and improved production efficiency
3Manufacturing precision
If the molten metal method or brazing method is used to form aluminum circuit on ceramic base material, then the aluminum circuit can be formed, but the manufacturing steps become longer due to necessary etching steps
Solution Approach 1:
The patent extracts and eliminates the etching step from the manufacturing process by using aluminum foil that can be directly bonded to the ceramic substrate and then selectively removed or patterned without requiring chemical etching, thereby reducing the number of manufacturing steps and time
Solution Approach 2:
The patent performs preliminary patterning or circuit design on the aluminum foil before bonding it to the ceramic substrate, so that the circuit pattern is already established and no additional etching steps are needed after bonding, thus reducing overall manufacturing time
4Manufacturing precision
If cold spraying method is used to form aluminum film on ceramic base material, then a dense aluminum film can be obtained, but large power consumption is required to heat inert gas and accelerate powder
Solution Approach 1:
The patent changes the temperature parameter of the aluminum material from cold spraying (room temperature) to a moderate temperature range that is higher than room temperature but significantly lower than the extreme temperatures required for cold spraying acceleration, thereby reducing energy consumption while still achieving dense film formation through controlled heating and pressure
Solution Approach 2:
The patent replaces the high-velocity mechanical acceleration system required for cold spraying with a thermal-field-based bonding approach, where moderate heating and pressure are used to achieve adhesion without requiring high-speed powder acceleration, thus reducing power consumption
5Manufacturing precision
If cold spraying method is used to form aluminum film on ceramic base material, then a dense aluminum film can be obtained, but expensive gas such as helium is necessary to highly accelerate the powder
Solution Approach 1:
The patent uses inexpensive materials (aluminum foil and common heating gases) instead of expensive helium gas required for cold spraying acceleration, achieving the desired dense film formation through a lower-cost material approach that eliminates the need for expensive propellant gases
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 enables efficient, high-adhesiveness aluminum circuit board production with reduced electric resistance and improved productivity, overcoming the limitations of previous techniques by using warm spraying to deposit metal layers directly onto ceramic substrates with controlled temperature and velocity, resulting in a dense and reliable metal layer.
Implementation Method 1
metal powder in a solid state collides with the base material. When the collision velocity is greater than a certain value, deformation near the interface between the powder and the base material progresses faster than the dissipation of heat generated by the high-speed plastic deformation to the surroundings through thermal conduction
Implementation Method 2
dissipation of heat generated by the high-speed plastic deformation to the surroundings through thermal conduction
Implementation Method 3
deformation near the interface between the powder and the base material progresses faster than the dissipation of heat generated by the high-speed plastic deformation
Data Source
AI summary
A method for manufacturing an aluminum circuit board including a step of spraying a heated metal powder containing aluminum particles and/or aluminum alloy particles to a ceramic base material, and of forming a metal layer on a surface of the ceramic base material. A temperature of at least a part of the metal powder is higher than or equal to a softening temperature of the metal powder and lower than or equal to a melting point of the metal powder at a time point of reaching the surface of the ceramic base material. A velocity of at least a part of the metal powder is greater than or equal to 450 m/s and less than or equal to 1000 m/s at the time point of reaching the surface of the ceramic base material.