Heat Dissipation Substrate Defect Reduction via Solid-State Sintering
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Solution Overview
Problem
Metal-diamond-system heat dissipation substrates face challenges with surface defects and poor plating quality due to diamond exposure and low sinterability, leading to voids and pinholes that hinder satisfactory Ni-based final plating and thermal conductivity.
Innovation Solution
A method involving plating a metallic layer on an alloy composite of metal and diamond, followed by heating and pressurizing at temperatures below the melting points of the metallic and alloy composites to create a substrate with few defects and improved thermal conductivity, ensuring a suitable coefficient of linear expansion and high thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If diamond powder is used to increase thermal conductivity, then thermal conductivity is improved, but surface defects and poor plating quality occur due to diamond exposure
Solution Approach 1:
The patent applies parameter changes by controlling the sintering temperature and pressure parameters to optimize the bonding between metal matrix and diamond particles. By adjusting these parameters, the metal fully penetrates and bonds with diamond surfaces, eliminating exposed diamond particles that cause plating defects while maintaining high thermal conductivity.
Solution Approach 2:
The patent uses composite materials by creating a metal-diamond composite where metal powder and diamond powder are mixed in specific ratios before sintering. The metal matrix completely encapsulates the diamond particles, forming a composite structure that achieves high thermal conductivity from diamond while preventing surface defects through proper material selection and proportioning.
2Temperature
If metal and diamond powder are sintered to form alloy composite, then thermal conductivity is improved, but sinterability is poor leading to voids and pinholes
Solution Approach 1:
The patent applies parameter changes by optimizing sintering temperature and pressure parameters. The sintering is performed at temperatures and pressures that enable complete penetration of metal into diamond particle surfaces, ensuring strong bonding and eliminating voids and pinholes while achieving the desired thermal conductivity.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining sintering conditions that allow continuous metal flow and penetration throughout the compacted powder mixture. This continuous action ensures complete wetting and bonding of diamond particles by metal, eliminating discontinuities such as voids and pinholes that would compromise reliability.
3Ease of manufacture
If conventional sintering is used for metal-diamond composite, then manufacturing is simple, but surface defects prevent satisfactory Ni-based final plating
Solution Approach 1:
The patent applies parameter changes by modifying sintering temperature and pressure parameters beyond conventional values. These elevated parameters ensure complete metal penetration and bonding with diamond particles, creating a defect-free surface that accepts Ni-based plating properly, thus maintaining manufacturing simplicity while achieving high plating quality.
4Temperature
If copper is used for heat dissipation substrate, then thermal conductivity is high, but coefficient of linear expansion is too large for high-performance semiconductor modules
Solution Approach 1:
The patent uses composite materials by combining metal powder (such as copper or copper alloys) with diamond powder in specific proportions. The diamond particles, having low thermal expansion, reinforce the metal matrix and reduce the overall coefficient of linear expansion of the composite while maintaining high thermal conductivity through the metal-diamond interface bonding.
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 process results in a heat dissipation substrate with a metallic layer having fewer than 5% defects, enabling satisfactory Ni-based final plating and meeting the stringent requirements for high-performance semiconductor modules, while also improving the relative density and thermal conductivity of the alloy composite.
Implementation Method 1
heating and pressurizing the metallic layer at a temperature which is equal to or lower than the melting point of the metallic layer and equal to or lower than the melting point of the alloy composite
Implementation Method 2
forming a metallic layer, by plating, on the surface of an alloy composite
Data Source
AI summary
A heat dissipation substrate having a metallic layer with few defects on its surface is obtained by a process including the steps of: forming a metallic layer by plating on the surface of an alloy composite mainly composed of a powder of a principal metal, additional metal and diamond; and heating and pressurizing alloy composite coated with metallic layer, at a temperature equal to or lower than melting points of the metallic layer and the alloy composite. Consequently a heat dissipation substrate is obtained which has a coefficient of linear expansion of 6.5 ppm/K or higher and 15 ppm/K or lower as well as a degree of thermal conductivity of 420 W/m·K or higher, the substrate having a metallic layer with few defects in its surface layer and thereby allowing for a Ni-based plating on which the void percentage in the solder joint will be 5% or lower.