Agglomerated BN Powder Structure for Heat Sheet Thermal Isolation
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Solution Overview
Problem
Existing agglomerated boron nitride (BN) powders used in heat dissipation sheets for semiconductor devices exhibit insufficient thermal conductivity and withstand voltage characteristics due to their anisotropic thermal conductivity and orientation issues.
Innovation Solution
An agglomerated boron nitride powder with a tap density of 0.6 g/ml or more and less than 0.8 g/ml, and an interparticle void volume of 0.5 ml/g or more, is developed. This powder has a card-house structure and specific particle size and intraparticle voidage ranges, enhancing thermal conductivity and withstand voltage in heat dissipation sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If spherical agglomerated BN particles are used to improve isotropic thermal conductivity, then thermal conductivity in thickness direction is improved, but withstand voltage characteristics deteriorate
Solution Approach 1:
The invention precisely controls critical parameters of the spherical agglomerated particles including tap density (0.4-0.8 g/ml), intraparticle voidage (30-70%), and agglomerate size (10-200 μm). By optimizing these parameters, the invention achieves a balance where the particles provide sufficient thermal conductivity while maintaining adequate withstand voltage characteristics through controlled voidage that prevents excessive particle proximity.
Solution Approach 2:
The invention applies different particle characteristics to different functional requirements: plate-like particles with high planar thermal conductivity are used where heat dissipation is prioritized, while spherical particles with controlled voidage are used where withstand voltage is critical. This local quality differentiation allows simultaneous optimization of both thermal and electrical properties in different regions of the molded body.
2Ease of manufacture
If high tap density BN powder is used to reduce particle orientation, then ease of filling is improved, but interparticle void volume decreases affecting thermal conductivity
Solution Approach 1:
The invention optimizes tap density to a specific range (0.4-0.8 g/ml) that balances filling ease and thermal conductivity. This parameter optimization ensures particles fill the mold cavity efficiently while maintaining sufficient interparticle void volume (0.3-0.7 ml/g) to accommodate resin penetration and prevent particle aggregation that would hinder heat transfer.
Solution Approach 2:
The invention uses spherical agglomerated particles that replicate the beneficial thermal conductivity properties of highly oriented plate-like structures while eliminating their orientation problems. The spherical geometry copies the heat dissipation function without the anisotropic alignment issues, achieving isotropic thermal performance.
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 developed agglomerated BN powder significantly improves the thermal conductivity and withstand voltage characteristics of heat dissipation sheets, making them suitable for high-quality, high-reliability power semiconductor modules with excellent heat dissipation performance.
Implementation Method 1
h-BN has a plate-like particle shape and a high thermal conductivity (usually, a thermal conductivity of about 400 W/m·K) in the planar direction of the plate (in the ab plane or (002) plane)
Data Source
AI summary
An agglomerated boron nitride powder, including a tap density of 0.6 g/ml or more and less than 0.8 g/ml and an interparticle void volume of 0.5 ml/g or more. A heat dissipation sheet, including the agglomerated boron nitride powder. An agglomerated boron nitride powder that enables a heat dissipation sheet to have improved thermal conductivity and good withstand voltage characteristics, a heat dissipation sheet containing the agglomerated boron nitride powder, and a semiconductor device including the heat dissipation sheet are provided.