Power Module Substrate With Variable Copper Thickness
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Solution Overview
Problem
Power module substrates face challenges in promptly dissipating heat from semiconductor devices while minimizing heat stress and preventing separation or cracking at the ceramic-copper joint interface due to thermal expansion coefficient differences, and existing manufacturing methods can lead to misalignment and reduced yield.
Innovation Solution
The power module substrate design includes a copper circuit plate with varying thicknesses, featuring a thicker first portion for heat transfer, a thinner second portion to reduce stress, and an optional third portion to prevent solder overflow, along with a method using inkjet etching to form precise protrusions and recesses, ensuring accurate bonding and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a thicker copper plate is used to increase heat dissipation, then heat dissipation performance is improved, but heat stress at the joint interface increases causing separation and cracks
Solution Approach 1:
The copper plate is designed with non-uniform thickness: a first thickness in the central region for optimal heat dissipation, and a second (smaller) thickness at the edges to reduce thermal stress concentration. This local variation in geometric property resolves the contradiction by allowing the plate to simultaneously achieve high heat dissipation in the center while maintaining joint interface stability at the edges.
2Loss of energy
If a thinner ceramic plate is used to increase heat dissipation, then heat dissipation performance is improved, but mechanical strength decreases
Solution Approach 1:
The invention uses a composite structure combining ceramic plate with copper plates of different thicknesses. The ceramic provides electrical insulation and structural support, while the copper plates provide thermal conduction. The specific thickness configuration of copper plates compensates for the reduced mechanical strength of thinner ceramic plates by providing additional structural reinforcement at critical locations.
3Loss of energy
If aluminum nitride ceramic is used to increase heat dissipation, then heat dissipation performance is improved, but manufacturing cost increases
Solution Approach 1:
The invention changes the thickness parameter of the copper plate to optimize heat dissipation performance. By adjusting the copper plate thickness configuration, the system achieves improved heat dissipation using more cost-effective alumina-based ceramics instead of expensive aluminum nitride ceramics, while maintaining acceptable thermal performance through optimized copper conduction paths.
4Loss of energy
If a thicker copper plate is used to increase heat dissipation, then heat dissipation performance is improved, but separation of copper plate edges from ceramic plate increases
Solution Approach 1:
The copper plate features local thickness variation with a first thickness in the center and a second (smaller) thickness at the edges. This design allows the central region to provide high heat dissipation while the thinner edges reduce thermal stress concentration and prevent separation from the ceramic plate, thus resolving the contradiction between heat dissipation performance and joint interface integrity.
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 enhances heat dissipation efficiency, reduces thermal stress, prevents separation and cracking, and improves manufacturing precision, leading to increased productivity and reliability of power module substrates.
Implementation Method 1
This power module substrate is used for mounting a power semiconductor device, such as a power integrated circuit (IC) or an insulated gate bipolar transistor (IGBT)... dissipate heat generated from a semiconductor device mounted on its copper circuit plate downward through the copper circuit plate, a ceramic plate, and a heat dissipation copper plate
Implementation Method 2
separation of the edges of the copper plate from the ceramic plate or cracks in the ceramic plate under heat stress at the joint interface between the ceramic plate and the copper plates resulting from the different thermal expansion coefficients of ceramics and copper
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A power module substrate allows prompt heat dissipation from a semiconductor device and avoids separation of a ceramic plate and a copper plate at their joint interface and cracks in the ceramic plate. A power module substrate (10) for mounting a semiconductor device (14) includes a ceramic plate (11), a copper circuit plate (12) on a main surface of the ceramic plate (11), and a heat dissipation copper plate (13) on a surface of the ceramic plate (11) opposite to the main surface. The copper circuit plate (12) includes at least one first copper circuit plate (12a) and at least one second copper circuit plate (12b) different from the first circuit board (12a). The first copper circuit plate (12a) includes a first portion (15a) on which the semiconductor device (14) is mountable, and a second portion (15b) outward from the first copper circuit plate (12a) and surrounding the first portion (12a) and thinner than the first portion (15a).