Ceramic Isolated Discrete Package for High Power Density
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Solution Overview
Problem
Existing discrete power semiconductor packages using DBC substrates exhibit reduced current and power density capabilities, particularly when employing wide band gap materials like SiC and GaN, necessitating external isolation methods that increase thermal resistance and compromise performance.
Innovation Solution
Employing a high thermal conductivity ceramic substrate, such as silicon nitride or aluminum nitride, with copper layers bonded via active metal brazing, to form an electrically isolated discrete package that enhances current and power capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aluminum oxide (Al2O3) ceramic substrate is used in DBC configuration for electrical isolation, then electrical isolation is provided, but current and power density capability are significantly reduced
Solution Approach 1:
The patent changes the material parameter of the ceramic substrate from aluminum oxide to high thermal conductivity ceramic materials such as aluminum nitride (AlN) or silicon nitride (Si3N4). These materials maintain the electrical isolation function while providing superior thermal conductivity (2-3 times higher than Al2O3), thereby resolving the contradiction between electrical isolation and current/power density capability
Solution Approach 2:
The patent employs composite structure consisting of high thermal conductivity ceramic substrate combined with copper layers in DBC configuration. The ceramic provides electrical isolation and thermal management, while the copper layers provide electrical connectivity and current carrying capability, creating a composite material system that achieves both isolation and high power density
2Reliability
If external thermally conductive isolation method is used between non-isolated discrete semiconductor package and heatsink, then electrical isolation is achieved, but thermal resistance increases and power handling capability is reduced
Solution Approach 1:
The patent merges the electrical isolation function and thermal management function into a single integrated ceramic substrate component. The high thermal conductivity ceramic substrate simultaneously provides electrical isolation between the mounting tab and heatsink while maintaining low thermal resistance for efficient heat dissipation, eliminating the need for separate external isolation components and their associated thermal penalties
3Reliability
If DBC substrate configuration is used for discrete isolated packages, then electrical isolation is provided, but thermal impedance is higher compared to non-isolated packages
Solution Approach 1:
The patent changes the thermal conductivity parameter of the ceramic substrate material from standard aluminum oxide to high thermal conductivity materials like aluminum nitride or silicon nitride. This parameter change reduces the thermal impedance of the substrate by a factor of 2-3 while maintaining the electrical isolation function, effectively resolving the contradiction between isolation and 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 use of high thermal conductivity ceramic substrates significantly improves current and power density, reducing thermal impedance by up to 54% and maintaining performance comparable to non-isolated packages, while eliminating the need for external isolation methods.
Implementation Method 1
The ceramic body is formed of a high thermal conductivity material
Implementation Method 2
copper layers bonded via active metal brazing
Data Source
AI summary
A substrate package arrangement may include a substrate that contains a ceramic body, a top metal layer, disposed on a top side of the ceramic body, and a bottom metal layer, disposed on a bottom side of the ceramic body, opposite the top surface. The substrate package arrangement may further include a lead structure, electrically connected to the top metal layer, and being electrically isolated from the bottom metal layer, wherein the substrate and lead structure are arranged in a discrete package, and wherein the ceramic body is formed of a high thermal conductivity material.