Boron Nitride Insulating Sheet With Filler Gradient for Adhesion
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Solution Overview
Problem
Conventional resin sheets containing boron nitride face challenges in enhancing both thermal conduction and adhesiveness, particularly when laminated with copper foil.
Innovation Solution
An insulating sheet comprising a thermosetting component and a thermally conductive filler with boron nitride, where the boron nitride content varies gradiently throughout the sheet's thickness to optimize thermal conduction and adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If boron nitride filler is used to enhance thermal conduction, then thermal conductivity is improved, but adhesiveness between the resin sheet and copper foil deteriorates
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of boron nitride filler concentration within the resin sheet. The filler concentration is higher in the inner region and lower near the adhesive surfaces, allowing different regions to have optimized properties: the inner region provides thermal conduction while the surface regions maintain adhesiveness. This resolves the contradiction by making the material composition spatially variable rather than uniform.
2Reliability
If ceramic substrate is used for heat dissipation, then thermal conduction is improved, but processability and multilayer formation deteriorate
Solution Approach 1:
The patent changes the material parameter from rigid ceramic to thermosetting resin composite, while optimizing the filler concentration parameter to achieve desired thermal conductivity. By adjusting the boron nitride filler content and distribution within the resin matrix, the patent achieves heat dissipation performance comparable to ceramic while maintaining the processability and flexibility of resin materials, enabling multilayer formation and various manufacturing processes.
3Reliability
If ceramic substrate is used, then thermal conduction is improved, but copper circuit peeling during thermal cycling worsens
Solution Approach 1:
The patent applies local quality by creating a gradient filler distribution that is lower near the copper circuit interface. This reduced filler concentration near the interface improves dimensional stability and reduces thermal stress during cycling, preventing copper circuit peeling. The inner region maintains high filler content for thermal conduction, while the surface regions have optimized composition for interface stability.
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 insulating sheet effectively enhances both thermal conduction and adhesiveness, reducing peeling issues at the interface with conductive layers and maintaining mechanical strength.
Implementation Method 1
a thermally conductive filler containing boron nitride... efficient dissipation of the generated heat... thermal conduction
Data Source
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AI summary
Provided is an insulating sheet capable of effectively enhancing thermal conduction and adhesiveness. The insulating sheet according to the present invention contains a thermosetting component and a thermally conductive filler, the thermally conductive filler contains boron nitride, the insulating sheet has a first surface on one side in a thickness direction and a second surface on the other side in the thickness direction, and a first content of the boron nitride in 100% by volume of a region having a thickness of 10% of a thickness of the sheet, from the first surface toward the second surface is smaller than a second content of the boron nitride in 100% by volume of a region having a thickness of 90% of a thickness of the sheet, from the second surface toward the first surface.