Heat Diffusing Plate Grain Diameter Gradient Circuit Board
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Solution Overview
Problem
Conventional circuit boards face the challenge of increased stress and risk of fracture in insulating substrates due to thermal expansion mismatch between the heat diffusing plate and insulating substrates, which can lead to warping and mechanical failure.
Innovation Solution
The circuit board design features a heat diffusing plate with varying grain diameters, larger near the surfaces and smaller towards the center, allowing for differential deformation to relax thermal expansion mismatch stress, while the metal circuit and dissipating plates have larger grain diameters to minimize warping and stress on insulating substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the heat diffusing plate is increased to improve thermal conductivity, then heat dissipation performance is improved, but stress on insulating substrates increases due to thermal expansion mismatch
Solution Approach 1:
The heat diffusing plate is designed with non-uniform grain diameter distribution: larger grain diameters (5-10 μm) near the upper and lower surfaces that contact insulating substrates, and smaller grain diameters (1-5 μm) in the central region. This local variation in microstructure creates differential deformation characteristics that reduce thermal expansion mismatch stress at the interface while maintaining adequate heat dissipation capability.
Solution Approach 2:
The invention changes the microstructural parameter (grain diameter) of the heat diffusing plate to resolve the contradiction. By controlling grain diameter to be larger at surfaces and smaller in the center, the plate achieves optimized mechanical compliance at interfaces while maintaining structural integrity and thermal performance throughout the component.
2Strength
If the heat diffusing plate deforms to relax thermal expansion stress, then stress on insulating substrates is reduced, but warping of the heat diffusing plate occurs
Solution Approach 1:
Different regions of the heat diffusing plate are given different grain diameters to perform different functions: surface regions with larger grains accommodate thermal expansion stress through localized deformation, while the central region with smaller grains maintains rigidity to prevent overall warping of the plate.
Solution Approach 2:
The heat diffusing plate is effectively segmented into different functional zones based on grain diameter: surface layers that are more compliant for stress relaxation, and a central core that is stiffer for maintaining shape stability. This segmentation allows simultaneous achievement of stress relaxation and warp suppression.
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 design effectively suppresses warping of both the heat diffusing plate and insulating substrates, enhancing the reliability and thermal conductivity of the circuit board while ensuring efficient heat dissipation.
Implementation Method 1
stress is applied to the insulating substrates when the heat diffusing plate is expanded and contracted by thermal history
Implementation Method 2
the heat diffusing plate relatively easily deforms in the above-described regions, and this deformation can relax stress generated by a thermal expansion mismatch between the insulating substrates and the heat diffusing plate
Implementation Method 3
a metallic heat diffusing plate used as a means for spreading heat from an electronic component, such as a power module, mounted on the metal circuit plate in the lateral direction
Data Source
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AI summary
A circuit board includes a metal circuit plate, a metallic heat diffusing plate below the metal circuit plate, a metallic heat dissipating plate below the heat diffusing plate, an insulating substrate disposed between the metal circuit plate and the heat diffusing plate and having an upper surface bonded to a lower surface of the metal circuit plate and a lower surface bonded to an upper surface of the heat diffusing plate, and an insulating substrate disposed between the heat diffusing plate and the heat dissipating plate and having an upper surface bonded to a lower surface of the heat diffusing plate and a lower surface bonded to an upper surface of the heat dissipating plate. A grain diameter of metal grains contained in the heat diffusing plate decreases from each of the upper surface and the lower surface of the heat diffusing plate toward a center portion of the heat diffusing plate in a thickness direction.