Silicon Nitride Solid Solution Composition for High-Temperature Insulation
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Solution Overview
Problem
Conventional silicon nitride sintered bodies experience a significant decrease in volume resistivity at high temperatures, compromising their insulation resistance in applications like power modules.
Innovation Solution
Incorporating specific elements such as Ti, Ge, Zr, Ag, Ba, or Hf as a solid solution in silicon nitride grains at concentrations between 0.01% to 0.15% by mass, with limited P, Cr, Mn, and Fe to 0.05% by mass or less, to maintain high volume resistivity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional silicon nitride sintered bodies are used, then high strength and thermal conductivity are achieved, but volume resistivity decreases markedly at high temperatures
Solution Approach 1:
The invention changes the chemical composition parameters by introducing specific elements (Ti, Ge, Zr, Ag, Ba, or Hf) as solid solutions in silicon nitride grains at controlled concentrations (0.01-0.15 mass%). This parameter modification suppresses the decrease in volume resistivity at high temperatures while preserving the high strength and thermal conductivity properties of silicon nitride sintered bodies
Solution Approach 2:
The invention creates a composite material system by incorporating multiple elements (specifically Ti, Ge, Zr, Ag, Ba, or Hf) as solid solutions within the silicon nitride grain structure. This composite approach at the grain level achieves improved electrical insulation at high temperatures while maintaining the base material's mechanical and thermal properties
2Reliability
If heating treatment is applied to reduce volume resistivity decrease, then insulation at high temperature improves, but additional process complexity is introduced
Solution Approach 1:
The invention applies preliminary action by incorporating the desired elements (Ti, Ge, Zr, Ag, Ba, or Hf) into the silicon nitride grain structure during the sintering process itself. This preliminary incorporation of functional elements eliminates the need for subsequent heating treatment steps, reducing process complexity while achieving the same effect of maintaining electrical insulation at high temperatures
3Reliability
If Mg or Y2O3 is added to improve high temperature insulation, then volume resistivity decreases less at high temperature, but the effect is insufficient
Solution Approach 1:
The invention improves upon existing solutions by changing the elemental composition parameters, specifically introducing Ti, Ge, Zr, Ag, Ba, or Hf elements at optimized concentrations (0.01-0.15 mass%). These parameter changes produce a more effective suppression of volume resistivity decrease at high temperatures compared to conventional Mg or Y2O3 additions
Solution Approach 2:
The invention effectively copies and improves upon the mechanism of existing solutions (Mg or Y2O3 additions) by using similar solid solution formation in silicon nitride grains, but achieves superior results by selecting different elements with more effective electronic structures for suppressing high-temperature electrical 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 silicon nitride sintered body maintains high volume resistivity and insulation resistance even at practical operating temperatures, suitable for substrates in power modules and other devices.
Implementation Method 1
containing at least one element selected from the group consisting of Ti, Ge, Zr, Ag, Ba, and Hf in silicon nitride grains constituting the sintered body, the at least one element being contained as a solid solution in the silicon nitride grains at a concentration of 0.01% to 0.15% by mass
Data Source
AI summary
The silicon nitride sintered body according to the present invention contains at least one element selected from the group consisting of Ti, Ge, Zr, Ag, Ba, and Hf in silicon nitride grains constituting the sintered body, and the at least one element is contained as a solid solution in the silicon nitride grains at a concentration of 0.01% to 0.15% by mass. The present invention provides a silicon nitride sintered body having a greatly smaller decrease in volume resistivity at high temperatures with respect to volume resistivity at room temperature than conventional silicon nitride sintered bodies.