Silicon Nitride Laminate Substrate With Controlled Interlayer Color Difference
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Solution Overview
Problem
Existing silicon nitride substrates face issues with heat dissipation and mechanical strength due to insufficient adhesion between layers, leading to defects such as pores and delamination, which degrade thermal conductivity and bending strength.
Innovation Solution
A silicon nitride substrate design with alternating major and intermediate layers, where the color difference between layers is controlled within specific ranges (0.1 ≤ CDna ≤ 1.4 and 0.1 ≤ CDnb ≤ 1.4) to ensure adequate adhesion, reducing oxidization and preventing defects during lamination and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple green sheets are laminated to increase substrate thickness for better heat dissipation, then heat dissipation performance is improved, but adhesion between layers deteriorates leading to pores and delamination
Solution Approach 1:
The invention applies preliminary action by controlling the color difference between green sheets before lamination to ensure adequate adhesion. By selecting green sheets with specific color difference ranges (ΔE ≤ 1.4), the adhesion quality is predetermined and controlled before the actual lamination process, preventing delamination and pore formation in the final sintered substrate.
Solution Approach 2:
The invention changes the parameter of color difference between green sheets as a control variable. By specifying that the color difference ΔE between adjacent green sheets should be 1.4 or less, the patent establishes a quantitative parameter control mechanism that ensures proper adhesion while allowing multiple layers to be laminated for enhanced heat dissipation.
2Reliability
If green sheets are laminated under heat and pressure, then adhesion between layers is improved, but oxidization occurs leading to color changes and potential defects
Solution Approach 1:
The invention performs preliminary action by controlling the color difference of green sheets before lamination. By ensuring that the color difference ΔE between adjacent green sheets is 1.4 or less, the patent preemptively compensates for potential oxidization effects during lamination, maintaining adhesion quality while accounting for the harmful oxidization that occurs during heat treatment.
3Strength
If sintering temperature is increased to improve substrate density and strength, then bending strength is improved, but thermal conductivity deteriorates due to excessive oxidization and defects
Solution Approach 1:
The invention changes the parameter control approach by focusing on the color difference parameter of green sheets before lamination. By controlling ΔE ≤ 1.4, the patent ensures proper adhesion and minimizes defects, enabling the sintering process to achieve high bending strength (≥650 MPa) while maintaining adequate thermal conductivity (≥60 W/m·K) without excessive oxidization.
4Temperature
If substrate thickness is reduced to improve heat dissipation efficiency, then heat dissipation performance is improved, but mechanical strength deteriorates
Solution Approach 1:
The invention applies composite material principles by creating a multi-layered structure through lamination of green sheets. By controlling the color difference between layers to ensure proper adhesion, the patent produces a composite sintered substrate that achieves both adequate mechanical strength (bending strength ≥650 MPa) and improved heat dissipation efficiency through optimized thickness and layer structure.
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 controlled color difference enhances thermal conductivity to at least 60 W/(m·K) and bending strength to at least 650 MPa, improving heat dissipation and mechanical integrity of the substrate.
Implementation Method 1
a dense laminated body is obtained by laminating a plurality of green sheets
Implementation Method 2
the laminated body is sintered in a nitrogen pressurized atmosphere at a temperature of not less than 1,600° C. and not more than 2,000° C.
Implementation Method 3
the binder content in each of the green sheets is 1 wt % or more and 10 wt % or less, carbon in the green sheets is 3 wt % or more and 10 wt % or less
Data Source
AI summary
A silicon nitride substrate includes major layers and intermediate layers. m+1 of the major layers and m of the intermediate layers are alternately arranged in a thickness direction. A color difference between an nth major layer and an nth intermediate layer from one surface (n being an integer) is taken as CDna. A color difference between a (n+1)th major layer and the nth intermediate layer is taken as CDnb. A first condition and a second condition are satisfied for all values of n from 1 to m. The first condition is when there is a continuous region having a length of not less than 100 μm in a first direction in which 0.1≤CDna≤1.4. The second condition is when there is a continuous region having a length of not less than 100 μm in the first direction in which 0.1≤CDnb≤1.4.