AlN Crystal Thermal Conductivity via Molten Aluminum Nitridation
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Solution Overview
Problem
Conventional aluminum nitride (AlN) sintered bodies exhibit insufficient thermal conductivity while maintaining electrical insulation, and attempts to enhance thermal conductivity by adding metal particles often impair insulating properties.
Innovation Solution
A method involving the formation of a molten aluminum layer on an AlN substrate in a non-oxidizing atmosphere, followed by heating in N2 gas to produce an AlN crystal with a hexagonal crystal structure, which inherits the substrate's crystal structure and reduces gaps between crystalline particles, thereby achieving excellent thermal conductivity without compromising insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AlN sintered body is used to maintain electrical insulation, then insulating property is preserved, but thermal conductivity is insufficient
Solution Approach 1:
The invention changes the physical and chemical parameters of the AlN material by forming a single-crystal structure with controlled orientation (c-axis orientation) and controlling impurity content to below 10^17 atoms/cm³, thereby achieving high thermal conductivity while maintaining electrical insulation
Solution Approach 2:
The invention uses a composite structure consisting of an AlN single-crystal layer formed on an AlN sintered body substrate, combining the electrical insulation of the sintered body with the high thermal conductivity of the single-crystal layer
2Loss of energy
If metal particles are added to enhance thermal conductivity, then thermal conductivity is improved, but insulating property is impaired
Solution Approach 1:
Instead of adding metal particles, the invention changes the fundamental structure from sintered to single-crystal AlN, achieving high thermal conductivity through crystal structure optimization without introducing conductive impurities that would compromise electrical insulation
3Ease of manufacture
If AlN crystal is produced by conventional sintering, then manufacturing is simple, but crystal structure has large gaps reducing thermal conductivity
Solution Approach 1:
The invention segments the manufacturing process into two stages: first forming an AlN sintered body substrate, then growing an AlN single-crystal layer on its surface, thereby combining the ease of sintering with the superior thermal properties of single crystal
Solution Approach 2:
The AlN sintered body is prepared in advance as a substrate before the single-crystal layer formation, providing a foundation that simplifies the overall manufacturing process while enabling high thermal conductivity
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 method produces a thermally conductive and electrically insulating material with enhanced thermal conductivity and maintained insulating properties, allowing for effective heat transfer while preventing deformation due to thermal expansion differences.
Implementation Method 1
the Al element in the molten aluminum layer reacts with the N element dissolved in the molten aluminum layer, whereby an AlN crystal can be produced
Implementation Method 2
the N2 gas dissolves in the molten aluminum layer
Implementation Method 3
The AlN crystal (AlN layer) produced in the reaction step can inherit the crystal structure of the hexagonal AlN crystalline particle on the AlN substrate surface
Implementation Method 4
By performing the molten aluminum layer-forming step in an atmosphere of non-oxidizing gas, the molten aluminum layer can be formed while preventing production of alumina (aluminum oxide)
Data Source
AI summary
Means for a thermally conductive and electrically insulating material 1 containing an AlN crystal 150 mainly comprising AlN, and a production method thereof. In production, a molten aluminum layer is formed on an AlN substrate 11 with at least its surface comprising AlN in an atmosphere of a non-oxidizing gas, and the molten aluminum layer is then heated in an atmosphere of N2 gas to form an AlN crystal 150 which mainly comprises an AlN layer 125. The means are also a thermally conductive and electrically insulating material having an AlN crystal and an Al gradient layer, and a production method thereof. In production, a heating step of forming a molten aluminum layer 15 on the AlN layer 125 and heating it in an atmosphere of N2 gas is repeated at least twice or more. At this time, the amount of the N2 gas dissolved in the molten aluminum layer is decreased as the heating step is repeated.