Bonded Substrate Edge Geometry for Heat-Cycle Circuit Boards
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Solution Overview
Problem
Existing circuit boards face challenges in achieving optimal heat cycle characteristics while maintaining a sufficient mounting region for electronic components, particularly when the metal plate thickness is increased, as existing designs do not adequately address the heat dissipation needs of high-power semiconductor elements like power ICs.
Innovation Solution
A bonded substrate design featuring a metal plate with a thickness between 0.5 mm and 2.0 mm, where the bonding member protrudes along the entire periphery and forms an inclined surface, satisfying specific geometric and thermal criteria to enhance heat dissipation and maintain a mounting region for electronic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the metal plate is increased to improve heat dissipation, then heat dissipation performance is improved, but the mounting region for electronic components is reduced
Solution Approach 1:
The bonding member protrudes from the edge of the metal plate in the thickness direction, creating a three-dimensional structure. This allows the bonding member to provide thermal management functionality without occupying horizontal mounting space on the metal plate surface, thus resolving the conflict between heat dissipation and mounting region availability.
Solution Approach 2:
The bonding member serves as an intermediary element that performs dual functions: bonding the metal plate to the substrate and providing thermal management through its protrusion structure. This mediator approach allows heat dissipation functionality to be added without directly reducing the mounting region on the metal plate.
2Temperature
If the thickness of the metal plate is increased to improve heat dissipation, then heat dissipation performance is improved, but heat cycle characteristics deteriorate
Solution Approach 1:
The invention optimizes specific parameters of the bonding member including protrusion length (10-150 μm), inclination angle (15-45 degrees), and thickness (0.2-1.0 mm). These parameter changes create an optimal balance between heat dissipation capability and heat cycle reliability, allowing the system to withstand thermal expansion and contraction stresses while maintaining effective heat management.
3Reliability
If the protrusion length of the bonding member is increased to improve heat cycle characteristics, then heat cycle characteristics are improved, but the mounting region is further reduced
Solution Approach 1:
The bonding member's protrusion is oriented in the thickness direction (vertical dimension) rather than extending in the horizontal plane. This dimensional approach allows the bonding member to achieve adequate protrusion length for heat cycle reliability without encroaching on the horizontal mounting region available for electronic components.
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 design achieves excellent heat cycle characteristics and secures a mounting region for electronic components, even with a large metal plate thickness, effectively managing high operation temperatures up to 250°C.
Implementation Method 1
heat is generated when the electronic component is mounted on the metal plate on which the circuit pattern is formed. In a case where such a circuit board is assembled in, for example, a portion of a product (not illustrated), and is operated, heat is generated from the electronic component.
Implementation Method 2
the bonded substrate and the circuit board are required to satisfy the heat cycle characteristics which are equal to or higher than predetermined criteria
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A bonded substrate (10) includes a substrate (20), a metal plate (30) forming a stacked state along with the substrate (20), and a bonding member (40). The metal plate (30) has a first surface (32) on the substrate (20) side and a second surface (34) on an opposite side of the first surface (32). In the metal plate, an edge of the first surface (32) is located outside an edge of the second surface (34) when viewed from a stacking direction. The bonding member (40) is disposed between the substrate (20) and the metal plate (30), so as to bond the metal plate (30) to the substrate (20), and protrudes from the edge over an entire periphery of the metal plate (30) when viewed from the stacking direction. In cut surfaces obtained by cutting the bonded substrate in the stacking direction, a peripheral surface length (A) from a portion corresponding to a peripheral edge of the first surface (32) to a portion corresponding to a peripheral edge of the second surface (34), a protrusion length of the bonding member (40), and a thickness (C) of the metal plate (30) satisfy first and second expressions. 0.032≤B/A+B≤0.400 0.5mm≤C≤2.0mm