Laminated Circuit Board Thermal Expansion Control
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Solution Overview
Problem
High-capacity modules, such as power modules in hybrid cars and electric vehicles, face issues with size, weight reduction, and heat dissipation due to thermal expansion of high exothermic elements, leading to poor junctions and potential module breakage from excessive heat.
Innovation Solution
A circuit board with a ceramic substrate and embedded conductive electrodes is used to laminate with high exothermic elements, allowing for efficient heat release and reducing thermal stress through a controlled thermal expansion coefficient difference between the substrate and the conductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If circuit boards are laminated to reduce size and weight, then module size and weight are reduced, but thermal expansion causes poor junctions and heat dissipation problems
Solution Approach 1:
The patent changes the material parameter of the circuit board substrate from conventional resin to ceramic material. This parameter change provides a lower thermal expansion coefficient that better matches the heat sink, preventing differential thermal expansion from causing poor junctions while maintaining the laminated compact structure.
Solution Approach 2:
The patent uses a composite structure where a ceramic substrate is combined with conductive electrodes to form a circuit board. This composite material approach allows the circuit board to simultaneously provide mechanical support, electrical connectivity, and thermal stability through the ceramic's low thermal expansion properties.
2Temperature
If heat sink is equipped to release heat, then heat dissipation is improved, but thermal expansion coefficient difference causes circuit board curvature
Solution Approach 1:
The patent changes the substrate material parameter from resin to ceramic, which fundamentally alters the thermal expansion characteristics. The ceramic material's lower thermal expansion coefficient reduces the differential expansion between the heat sink and circuit board, preventing board curvature while maintaining effective heat dissipation.
Solution Approach 2:
The patent directly addresses the thermal expansion issue by selecting a ceramic substrate with a thermal expansion coefficient that better matches the heat sink material. This reduces the thermal mismatch that would otherwise cause differential expansion and circuit board deformation during thermal cycling.
3Loss of energy
If wiring length is reduced to lower loss and surge, then connection efficiency is improved, but layout complexity increases in laminated structure
Solution Approach 1:
The patent transitions from planar circuit layout to a three-dimensional laminated structure. By stacking circuit boards vertically, the patent achieves shorter current paths and reduced wiring length between power and control circuits, thereby lowering energy loss and surge voltage despite the increased spatial complexity of the laminated assembly.
Solution Approach 2:
The patent merges multiple circuit functions into a compact laminated structure where power circuits and control circuits are integrated on different layers. This consolidation reduces the overall wiring length and connection points compared to separate planar layouts, decreasing energy loss and electromagnetic interference.
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 configuration enhances heat dissipation, reduces module weight, and prevents breakage by ensuring a reliable connection and efficient heat transfer from high exothermic elements, improving the overall reliability and performance of high-capacity modules.
Implementation Method 1
A circuit board with a ceramic substrate and embedded conductive electrodes is used to laminate with high exothermic elements, allowing for efficient heat release and reducing thermal stress
Implementation Method 2
reducing thermal stress through a controlled thermal expansion coefficient difference between the substrate and the conductor
Data Source
Figure 1~2
Figure 3(a)~3(c)
Figure 4(a)~4(c)
AI summary
[Summary] [Subject] In a high-capacity module, while attaining reduction in size and weight, reduction in serge, and reduction in a loss, overheating of the module due to the curvature of a power circuit board accompanying thermal expansion of a composition member of the power circuit due to heat generation from a high exothermic element should be prevented. [Solution means] A drive circuit is laminated via a high exothermic element disposed on a power circuit, and it is configured so that the average thermal expansion coefficient of the side of the power circuit of the drive circuit board may be larger than the average thermal expansion coefficient of the side opposite to the power circuit. Thereby, the drive circuit board will be curved in the same direction as the power circuit board when the power circuit board is curved due to heat generation from the high exothermic element accompanying the operation of the module. Thereby, in a high-capacity module, while attaining reduction in size and weight, reduction in serge, and reduction in a loss, poor junction between the high exothermic element of the power circuit and the drive circuit board can be suppressed and heat generating from the high exothermic element can be more effectively released.