Card Edge Connector Preload Structure for Signal Integrity
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Solution Overview
Problem
Conventional card edge connectors experience signal integrity deterioration at high speeds and high densities due to stub resonances caused by the length of preloaded conductive elements, which affects their performance in modern electronic assemblies.
Innovation Solution
A card edge connector design that preloads conductive elements by deflecting them from their rest state using a member positioned farther from the mating end, reducing the length of the tips and minimizing the risk of damage from card insertion while maintaining or increasing the contact force, thereby improving signal integrity and operating frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the conductive elements are preloaded by deflecting them from their rest state to increase contact force, then the contact force is improved, but the tips of the conductive elements extend into the opening and risk being damaged by card insertion
Solution Approach 1:
The conductive element is divided into distinct functional segments: a contact portion with curved surface for mating, an intermediate portion for preloading, and a tip portion. This segmentation allows each segment to perform its specific function - the contact portion provides reliable electrical contact, the intermediate portion receives preload force, and the tip portion is protected from damage
Solution Approach 2:
The preload member contacts the conductive element at a point farther from the opening, applying force in a direction that deflects the contact portion toward the card while keeping the tip retracted. This dimensional approach to force application resolves the contradiction between contact force and tip protection
2Force
If the tips of the conductive elements are extended into the opening to increase deflection and contact force, then the contact force is improved, but stub resonances occur at high frequencies deteriorating signal integrity
Solution Approach 1:
By segmenting the conductive element and applying preload at the intermediate portion rather than extending the tip, the design eliminates the stub resonance issue while maintaining contact force. The contact portion is sufficiently long to provide reliable contact without extending into the opening, thus avoiding high-frequency resonance
Solution Approach 2:
The design changes the parameters of the conductive element including the curvature of the contact portion and the position where preload is applied. These parameter changes optimize both contact force and signal integrity by preventing stub resonances
3Force
If the conductive elements are configured to be deflected from rest state to increase contact force, then the contact force is improved, but the structure becomes more complex requiring additional preload members
Solution Approach 1:
The preload member serves multiple functions: it applies preload force to the conductive elements, positions them correctly, and protects the tips from damage. This multi-functionality reduces the need for additional separate components, thereby managing structural complexity while achieving improved contact force
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 design enhances signal integrity and allows the connector to operate at higher frequencies, such as greater than 40 Gbps NRZ, by reducing stub resonances and ensuring reliable electrical and mechanical connections without damaging the connector.
Implementation Method 1
The contact between the at least one compliant, conductive element and the member may deflect the at least one compliant, conductive element from its rest state
Data Source
AI summary
A card edge connector with an improved manner of creating a preload force on conductive elements held by a housing. The housing may include a member and an opening at a mating end. Each conductive element may have a contact portion curving inwardly relative to the opening and a tip extending from the contact portion towards the mating end. Each contact portion may form an electrical connection with an edge pad of a card to be inserted into the opening. The conductive elements may be configured to have a rest state in order to create a proper force to be exerted on the edge pads. The member may preload the conductive elements by contacting the conductive elements from a location farther from the mating end than the contact portion, which may avoid damage upon insertion of a card into the connector without the need for long tips of the conductive elements. As a result, the connector may operate at high frequencies.