Paddle Card Dogbone Contact Pads for High-Speed Impedance Control
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Solution Overview
Problem
Conventional cable interconnection systems experience impedance discontinuities when differential signal wires are terminated to elongated rectangular contact pads on circuit boards, leading to crosstalk and electrical noise in high-speed data transmission applications.
Innovation Solution
A specially configured paddle card with two distinct contact sections spaced apart along the circuit board for each signal wire, forming a 'dogbone' configuration, reduces the overall termination area and capacitance, thereby minimizing impedance discontinuity and improving the impedance profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional elongated rectangular contact pads are used for wire termination, then the termination structure is simple and easy to manufacture, but impedance discontinuities occur leading to crosstalk and electrical noise
Solution Approach 1:
The single elongated rectangular contact pad is segmented into two separate contact pads positioned along the length of the circuit board. This segmentation reduces the overall capacitance of the termination structure, thereby reducing impedance discontinuity and minimizing crosstalk and electrical noise in high-speed data transmission applications
Solution Approach 2:
The contact pads are designed with different dimensions and positions to optimize local electrical characteristics. The first and second contact pads have specific length and width dimensions that are tailored to reduce impedance discontinuity at the termination point, creating locally optimized electrical properties that reduce crosstalk while maintaining manufacturability
2Reliability
If a single elongated contact pad is used, then the termination area is large providing good electrical connection, but capacitance increases causing impedance discontinuity
Solution Approach 1:
The contact pad structure is divided into two separate pads rather than one continuous pad. This segmentation reduces the total capacitance while maintaining reliable electrical connection through the two discrete contact points, thereby improving impedance profile uniformity without sacrificing connection reliability
Solution Approach 2:
The contact pads are arranged in a specific spatial configuration along the length of the circuit board, utilizing the longitudinal dimension to distribute the electrical connection points. This dimensional arrangement optimizes the balance between connection reliability and capacitance reduction, achieving better impedance control
3Device complexity
If conventional termination is used, then the structure is simple, but impedance discontinuity curve is irregular causing signal degradation at high frequencies
Solution Approach 1:
The contact pads are designed with specific length and width dimensions (first length, first width, second length, second width) that are optimized to control the impedance profile. These localized dimensional specifications create a more uniform impedance discontinuity curve, improving impedance profile control while maintaining structural simplicity
Solution Approach 2:
The impedance profile is controlled by carefully selecting and optimizing the geometric parameters of the contact pads, including their lengths, widths, and spacing. By adjusting these parameters, the impedance discontinuity is minimized and the impedance profile becomes more uniform, particularly at high frequencies, without significantly complicating the termination structure
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 dual contact pad configuration reduces crosstalk and electrical noise by flattening the impedance discontinuity curve, achieving a better impedance profile and lower insertion loss, especially at high frequencies, thus enhancing the performance of cable and connector structures in high-speed data transmission.
Implementation Method 1
The elimination of this extra conductive surface area reduces the capacitance, as compared to a regular, elongated rectangular contact pad, thereby reducing the impedance discontinuity that normally occurs in transition from the structured order of the cable wires to their termination on the surface of the circuit board
Data Source
AI summary
A paddle card construction disclosed for use in connecting electronic devices together. The paddle card takes the form of a circuit board that has a plurality of conductive contact pads arranged thereon in pairs. The contact pads of each pair are spaced apart from each other to provide a pair of points to which cable wire free ends may be terminated, such as by soldering. The spacing of the pads apart from each other in effect reduces to amount of capacitance in the cable wire termination area on the circuit board, thereby reducing the impedance and insertion loss in that area at high frequencies. The contact pads of each pair may be further interconnected together by a thin, conductive trace that extends lengthwise between the contact pads.