Ceramic-Copper Power Module Substrates With Reduced Warping
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Solution Overview
Problem
The existing methods for manufacturing power module substrate boards from large ceramic boards result in warping due to differences in stress between the front and back surfaces, leading to inaccuracies in circuit patterns and reduced productivity.
Innovation Solution
A method involving the formation of a bonded body with a ceramic board divided by grooves, where a thicker circuit layer-forming copper layer is composed of multiple first copper layers and a thinner metal layer-forming copper layer is bonded on the back, reducing stress differences and warping by adjusting the thickness and area ratios of the copper layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large area ceramic board is used to manufacture multiple power module substrate boards at once, then productivity is improved, but warping occurs due to stress differences between front and back surfaces
Solution Approach 1:
The ceramic board is divided into multiple substrate board regions by dividing grooves, allowing simultaneous manufacturing of multiple power module substrate boards while maintaining controllable stress distribution in each segment
Solution Approach 2:
Metal boards with different thicknesses are selectively bonded to the front and back surfaces of the ceramic board to create asymmetric stress compensation, counteracting the warping caused by thermal expansion differences during the bonding process
2Manufacturing precision
If metal boards of different thicknesses are bonded on front and back surfaces of the ceramic board, then circuit layer thickness requirements are met, but stress imbalance causes warping
Solution Approach 1:
Thinner metal boards are bonded to the back surface of the ceramic board to counterbalance the stress generated by thicker metal boards on the front surface, preventing warping while allowing the front circuit layer to achieve the required thickness
3Temperature
If the metal board on the circuit layer side is made thicker to improve heat spreading, then heat dissipation is improved, but warping increases and may break the ceramic substrate board
Solution Approach 1:
A thinner metal board is bonded to the back surface of the ceramic board to counterbalance the stress from the thicker front metal board, enabling the front circuit layer to achieve sufficient thickness for heat dissipation without causing excessive warping or board breakage
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 approach allows for accurate formation of circuit and metal layers on the substrate boards, improving productivity by minimizing warping and ensuring high accuracy in pattern formation.
Implementation Method 1
a metal board made of aluminum or copper is brazed on a ceramic base material (a ceramic board)
Data Source
Figure 1A~1D
Figure 2
Figure 3A~3C
AI summary
To provide a method of manufacturing power module substrate board at high productivity and a ceramic-copper bonded body in which warps are reduced. In a bonded body-forming step, a circuit layer-forming copper layer consisting of a plurality of first copper layers is formed by arranging and bonding a plurality of first copper boards on a first surface of a ceramic board, and a metal layer-forming copper layer consisting of a second copper layer with a smaller arrangement number than that of the first copper layers is formed by bonding a second copper board having a larger planar area than that of the first copper board and a smaller thickness than that of the first copper board so as to cover at least two of adjacent substrate board-forming areas on a second surface of the ceramic board among the substrate board-forming areas partitioned by the dividing groove.