Substrate Connecting Structure Stress Reduction
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Solution Overview
Problem
Existing substrate connecting structures experience stress at the joining portion due to the difference in linear expansion coefficients between the base material and the connection metal body, leading to potential cracking and reduced reliability.
Innovation Solution
A substrate connecting structure is designed with a connection metal body that includes a disc-shaped connecting portion and a cylindrical projection inserted into a through hole, where the connection is made only at the distal end surface of the projection, eliminating the need for metal bonding material between the wall surface and the projection, and using a metal bonding material to join the connection metal body with both the wiring layer and the mounted component, thereby reducing stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a connection metal body is inserted into the through hole and joined with metal bonding material to mounted components, then heat dissipation is improved, but stress is generated due to difference in linear expansion coefficients between base material and connection metal body
Solution Approach 1:
The patent extracts the metal bonding material from the through hole region, allowing the connection metal body to be inserted into the through hole without bonding material in that area. The metal bonding material is only used at the surface mounting region, separating the thermal conduction path from the stress-prone bonding region.
Solution Approach 2:
The connection structure is segmented into distinct regions: the through hole region contains only the connection metal body for thermal conduction, while the surface region contains the metal bonding material for mechanical bonding. This segmentation allows each region to fulfill its specific function without compromising the other.
2Strength
If metal bonding material is used to join connection metal body with base material, then bonding strength is improved, but stress concentration occurs at the joining portion
Solution Approach 1:
The patent removes the metal bonding material from the through hole region, eliminating the source of stress concentration. The connection metal body stands alone in the through hole, bonded only to the wired surface, which distributes stress more effectively.
3Strength
If connection metal body is extensively bonded with base material, then bonding strength is improved, but heat dissipation efficiency is reduced due to stress and potential cracking
Solution Approach 1:
By extracting the metal bonding material from the through hole region, the patent creates a clear thermal conduction path from the mounted component through the connection metal body to the wired surface, eliminating thermal resistance caused by bonding material in the heat path.
Solution Approach 2:
The thermal conduction path is segmented to be direct and unobstructed in the through hole region, while the bonding function is segmented to occur only at the surface mounting region. This allows optimal heat dissipation without compromising bonding strength.
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 reduces stress at the joining portion, increases bonding strength, and maintains high conductivity and heat dissipation efficiency by minimizing the contact area between the connection metal body and the base material, thus prolonging the structure's lifespan and reliability.
Implementation Method 1
the mounted component and the connection metal body are joined by a first joining portion formed from a metal bonding material
Implementation Method 2
the connecting portion and the wiring layer connecting portion are joined by a second joining portion formed from a metal bonding material
Data Source
AI summary
A substrate connecting structure includes a substrate that includes a flat base material having a first surface and a second surface at a side opposite to the first surface, a first wiring layer arranged on the first surface, and a second wiring layer arranged on the second surface, a through hole extending through the base material, a connection metal body that includes a connecting portion connected to the second wiring layer and a projection inserted into the through hole, and a mounted component mounted on the substrate. The connection metal body is connected to the mounted component only at a distal end surface of the projection.