PCB Interposer Via Structure for Thermal Expansion Crack Resistance
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Solution Overview
Problem
Electronic devices with multiple printed circuit boards (PCBs) face the risk of cracks due to differences in thermal expansion coefficients, which can compromise the structural integrity of the interposer connecting the PCBs.
Innovation Solution
An interposer substrate with via structures, including pads and vias, is designed to connect PCBs, featuring a dielectric core portion and boundary portion to manage thermal expansion, ensuring stable connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple PCBs are connected using an interposer, then wiring space efficiency is improved, but the risk of cracks increases due to thermal expansion differences
Solution Approach 1:
The interposer via structure is divided into multiple pads (first pad, second pad, third pad, fourth pad) connected by multiple vias (first via, second via, third via) in series. This segmentation allows each pad and via to independently accommodate thermal expansion, preventing crack propagation through the entire connection path while maintaining electrical connectivity between stacked PCBs.
2Productivity
If via structures are used to connect PCBs, then mounting space efficiency is improved, but thermal expansion stress concentrates in the via structures
Solution Approach 1:
Each pad in the via structure is designed with specific local characteristics - the pads are spaced apart and connected by multiple vias, creating localized stress distribution zones. This local quality design allows each segment to independently manage thermal expansion stress, preventing stress concentration in any single location while maintaining overall connection integrity.
3Reliability
If pads are spaced apart in the interposer substrate, then thermal expansion management is improved, but electrical connection complexity increases
Solution Approach 1:
Multiple vias are nested in series between the spaced pads, with each via connecting to the next in a sequential manner. This nested arrangement allows the complex multi-via structure to be organized in a compact, systematic way that manages thermal expansion through the spaced pads while keeping the electrical connection path clear and manufacturable.
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 effectively mitigates the risk of cracks by providing a stable and efficient electrical connection between PCBs, enhancing the structural integrity and operational reliability of the electronic device.
Implementation Method 1
In view of differences in thermal expansion coefficients within materials used in connecting the assembly, a risk of cracks may arise in the structure
Data Source
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AI summary
An interposer for connecting printed circuit boards (PCBs) includes an interposer substrate including a first surface and a second surface that is opposite to the first surface and at least one via structure disposed on the interposer substrate. The at least one via structure may include a first pad disposed on the first surface, a second pad spaced apart from the first pad and disposed in the interposer substrate, wherein the second pad includes a first body and at least one first opening passing through the first body, a third pad spaced apart from the second pad, at least one first via disposed between the first pad and the second pad and connected to the first body of the second pad, and a second via disposed between the second pad and the third pad.