Card Edge Connector Mounting Geometry for 64 Gbps Signal Integrity
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Solution Overview
Problem
Existing electrical connectors face challenges in maintaining signal integrity at high speeds due to impedance mismatch between terminals and memory cards, leading to signal distortion and limited manufacturing tolerance.
Innovation Solution
The design incorporates terminals with narrower mounting ends and flat surfaces, allowing larger solder balls to be attached, along with an organizer for secure attachment, which reduces impedance changes and increases manufacturing tolerance, and uses circular contact pads for improved signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional terminal designs are used, then manufacturing is simpler, but impedance mismatch occurs between terminals and memory cards causing signal distortion
Solution Approach 1:
The terminal design features a mounting end with a narrower width compared to the intermediate portion, creating local geometric variation. This narrowing at the mounting end (e.g., from 0.5mm to 0.3mm width) locally adjusts the impedance characteristics to better match memory card requirements, resolving the impedance mismatch problem while maintaining overall terminal functionality
Solution Approach 2:
The invention introduces a new dimensional parameter - the width of the mounting end - that is distinct from the intermediate portion width. By controlling the mounting end width to be narrower, the design adds a dimensional degree of freedom for impedance adjustment, enabling precise impedance matching without complicating the overall terminal structure
2Manufacturing precision
If larger solder balls are used, then manufacturing tolerance increases, but terminal design becomes more complex
Solution Approach 1:
The terminal structure incorporates a localized narrowing at the mounting end region, creating a specific geometric feature (narrower width) that accommodates larger solder balls. This local modification allows the use of larger solder balls with better manufacturing tolerance while keeping the rest of the terminal structure simple and straightforward
Solution Approach 2:
The terminal is pre-designed with a narrowed mounting end section before soldering occurs. This preliminary geometric preparation creates space and proper alignment for larger solder balls, enabling them to be attached without requiring complex adjustment or alignment procedures during assembly
3Reliability
If narrower mounting ends are used, then impedance matching improves, but mechanical strength decreases
Solution Approach 1:
The terminal design applies local quality variation by narrowing only the mounting end portion while keeping the intermediate portion wider. This creates a localized impedance-matching region without compromising the overall mechanical strength of the terminal, as the broader intermediate section maintains structural integrity
Solution Approach 2:
The design utilizes dimensional variation across different sections of the terminal - the mounting end width is reduced in one dimension to improve impedance matching, while the intermediate portion maintains a larger cross-section to preserve mechanical strength. This multi-dimensional approach allows simultaneous optimization of electrical and mechanical properties
Data Source
AI summary
A connector for high density, high speed, and high performance electronic systems. The connector has terminals held in a housing. Each terminal has a mating end, a mounting end, and an intermediate portion inbetween. A pair of cuts are disposed on opposite sides of the mounting end such that the mounting end is narrower than the intermediate portion. Each mounting end has a flat surface configured for a solder ball to be attached thereto and narrower than a diameter of the solder ball. This enables the solder ball to be reliably mounted to a contact pad on a circuit board that sized smaller than the solder ball. The contact pad can have a round shape such that a conductive trace can extend in any direction therefrom, which provides flexible routing. Such a configuration meets signal integrity requirements in connectors designed for 64 Gbps and beyond, while conforming to a standard that constrains mating and mounting interfaces.