Circuit Board Metal Layer Hooked Bond Thermal Stress
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Solution Overview
Problem
Circuit boards with metal and ceramic components bonded via a brazing material often experience detachment due to differences in thermal expansion coefficients, leading to reliability issues.
Innovation Solution
A circuit board configuration featuring a metal layer with a first metal portion in contact with the ceramic board, a second metal portion in contact with the metal plate, and a third metal portion between them, where the first metal portion extends and spreads laterally along the second metal portion, creating a hooked bond to enhance bonding strength and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal plate is bonded to a ceramic board via a brazing material, then electrical connection and heat radiation are achieved, but the metal plate detaches from the ceramic board due to difference in thermal expansion coefficients
Solution Approach 1:
The metal layer is divided into multiple portions (first, second, and third metal portions) with different functions. The first metal portion bonds to the ceramic board, the second metal portion contacts the metal plate, and the third metal portion acts as an intermediate layer. This segmentation allows each portion to be optimized for its specific function, particularly in managing thermal expansion differences and bonding interfaces.
Solution Approach 2:
The first metal portion extends in the thickness direction to penetrate the third metal portion and spreads out in the lateral direction along the second metal portion. This creates a three-dimensional hooked structure that transforms a simple planar bond into a multi-dimensional mechanical interlock, significantly enhancing bond stability and preventing detachment under thermal stress.
2Strength
If a simple metal layer structure is used, then manufacturing is easy, but the bond between metal plate and ceramic board is weak and prone to detachment
Solution Approach 1:
The metal layer is divided into multiple portions (first, second, and third metal portions) with different functions. The first metal portion bonds to the ceramic board, the second metal portion contacts the metal plate, and the third metal portion acts as an intermediate layer. This segmentation allows each portion to be optimized for its specific function, particularly in managing thermal expansion differences and bonding interfaces.
Solution Approach 2:
The first metal portion extends in the thickness direction to penetrate the third metal portion and spreads out in the lateral direction along the second metal portion. This creates a three-dimensional hooked structure that transforms a simple planar bond into a multi-dimensional mechanical interlock, significantly enhancing bond stability and preventing detachment under thermal stress.
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 configuration solidifies the bond between the metal plate and ceramic board, preventing detachment and providing a circuit board with improved long-term reliability, even under thermal stress.
Implementation Method 1
A part of the first metal portion extends toward a direction of the second metal portion such that the part of the first metal portion penetrates the third metal portion. The part of the first metal portion spreads out in a lateral direction along the second metal portion. Accordingly, the first metal portion is hooked onto the third metal portion.
Data Source
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AI summary
[Object] To provide a circuit board which has good long-term reliability. [Solution] A circuit board of the present invention includes a ceramic board and a metal plate on the ceramic board via a metal layer. The metal layer includes a first metal portion which is in contact with the ceramic board, a second metal portion which is in contact with the metal plate, and a third metal portion between the first metal portion and the second metal portion. A part of the first metal portion extends toward a direction of the second metal portion such that the part of the first metal portion penetrates the third metal portion, and spreads out in a lateral direction along the second metal portion.