Recessed Metal Posts for Combined Substrate Thermal Stress
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Solution Overview
Problem
In combined substrates, thermal deformation of substrates leads to internal stress between metal posts and solder bumps, reducing the reliability of electrical connections.
Innovation Solution
The use of recessed surfaces on the metal posts, formed through copper plating, allows for increased contact area and bonding strength of solder, enhancing the reliability of electrical connections between substrates by allowing positional displacement and reducing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal posts are soldered to solder bumps in combined substrates, then electrical connections are established between substrates, but thermal deformation causes internal stress that reduces connection reliability
Solution Approach 1:
The invention applies curvature by forming recessed surfaces on the metal posts instead of using flat surfaces. These recessed surfaces allow the solder to conform to the curved geometry, creating a larger bonding interface that can better accommodate thermal deformation and reduce internal stress in the combined substrate structure.
Solution Approach 2:
The invention changes the surface geometry parameter of the metal posts from flat to recessed/curved. This parameter change increases the surface area available for solder bonding and allows the solder joint to better absorb thermal expansion and contraction forces, thereby reducing internal stress while maintaining electrical connection reliability.
2Strength
If standard flat metal post surfaces are used, then manufacturing is simpler, but bonding strength of solder is insufficient due to reduced contact area
Solution Approach 1:
The recessed surfaces on the metal posts provide increased contact area for solder bonding, enhancing bonding strength. The curved geometry allows solder to flow into and conform to the recessed areas, creating stronger mechanical and metallurgical bonds compared to flat surfaces.
Solution Approach 2:
By changing the surface geometry from flat to recessed, the invention increases the effective bonding surface area without significantly complicating the manufacturing process. The recessed surfaces can be formed through standard plating or machining processes, making the enhancement practical for production.
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 solution improves the reliability of electrical connections by increasing the bonding strength of solder and reducing thermal deformation-induced stress, ensuring a stable and reliable connection between substrates.
Implementation Method 1
The use of recessed surfaces on the metal posts, formed through copper plating
Data Source
AI summary
A combined substrate includes a first substrate having multiple first metal posts, a second substrate having multiple second metal posts such that the second metal posts are positioned to oppose the first metal posts, respectively, and multiple solder structures interposed between the first metal posts and the second metal posts, respectively. The first metal posts and/or the second metal posts have recessed surfaces formed such that the solder structures are formed on the recessed surfaces, respectively.