PCB Edge Bond Dam for High-Frequency Solder Ball Isolation
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Solution Overview
Problem
Conventional chip packaging schemes using edge bond material often result in edge bond material contacting solder connections, leading to impedance imbalance and electrical channel performance loss, particularly at high frequencies like 28 GHz, due to return loss degradation.
Innovation Solution
A dam is formed on the printed circuit board (PCB) to prevent edge bond material from interfacing with solder balls, effectively confining it to the edge region and preventing contact with signal transmission areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If edge bond material is used to secure chip package to PCB, then mechanical reliability is improved, but electrical performance deteriorates due to impedance imbalance caused by contact with solder connections
Solution Approach 1:
The patent segments the bonding area by introducing a dam structure that divides the space between chip package and PCB into two regions: an edge region where edge bond material is applied for mechanical reliability, and a central region where solder connections are protected from edge bond material contact, preserving electrical performance
Solution Approach 2:
The dam acts as an intermediary structure between the edge bond material and the solder connections. It physically blocks the edge bond material from contacting the solder connections, thereby preventing impedance imbalance while still allowing edge bond material to fulfill its mechanical bonding function
2Stability of the object's composition
If edge bond material flows between chip package and PCB, then complete coverage is achieved, but signal transmission quality deteriorates due to contact with signal-carrying solder balls
Solution Approach 1:
The dam segments the bonding area into a covered region where edge bond material provides complete coverage for stability, and a protected region where solder connections are shielded from edge bond material, preventing harmful contact with signal-carrying balls
Solution Approach 2:
The dam serves as an intermediary barrier that allows edge bond material to achieve complete coverage in the edge region while preventing it from reaching the solder connections, thus eliminating the harmful effect on signal transmission quality
3Device complexity
If no dam structure is used, then device complexity is reduced, but electrical channel performance deteriorates due to return loss degradation at high frequencies
Solution Approach 1:
The dam introduces a simple segmented structure that divides the bonding area into protected and uncovered regions, preventing edge bond material from contacting solder connections and thereby maintaining electrical channel performance without significant increase in device complexity
Data Source
AI summary
An electronic device and methods for fabricating the same are disclosed herein that utilize a dam formed on a printed circuit board (PCB) that is positioned to substantially prevent edge bond material, utilized to secure a chip package to the PCB, from interfacing with the solder balls transmitting signals between the PCB and chip package.