From 04/04/2014 to *8/2/2012
1. “A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board (PWB) or etched wiring board. Printed circuit boards are used in virtually all but the simplest commercially produced electronic devices.
A PCB populated with electronic components is called a printed circuit assembly (PCA), printed circuit board assembly or PCB Assembly (PCBA). In informal use the term "PCB" is used both for bare and assembled boards, the context clarifying the meaning.
Alternatives to PCBs include wire wrap and point-to-point construction. PCBs must initially be designed and laid out, but become cheaper, faster to make, and potentially more reliable for high-volume production since production and soldering of PCBs can be automated. Much of the electronics industry's PCB design, assembly, and quality control needs are set by standards published by the IPC organization.”
(Wikipedia, Circuit Boards, 8/2/2012)
“Recent progress in devices utilizing radio waves, such as mobile phones, wireless LAN (Local Area Network), GPS (Global Positioning System), and automotive radar has been prolific. With the significant increase in the volume of information transmitted, telecommunication signals are requiring higher frequencies, and telecommunication devices are being downsized. Thus, there is now a strong demand for RF devices having smaller and more lightweight electronic components which transmit information at high speeds.
State-of-the-art telecommunication devices use high-speed microprocessors working at operating frequencies exceeding 500 MHz, typically from 1-10 GHz, and corresponding signal frequencies have been increasing rapidly in order to process a larger volume of information in a shorter time.
As signal delay time increases in proportion to the square root of the dielectric constant of the circuit board, the choice of this dielectric substrate can have a significant impact on processing and transmission speed.
Printed-circuit boards also dissipate electromagnetic energy during signal transmission, and this effect is magnified at the higher frequencies required in modern wireless and broadband applications. This transmission results in energy loss from the electronic component in the form of heat, which can further compromise the speed and efficiency of the device.
Two properties that play a significant role in high-speed circuit design are the dielectric constant (Dk) and dissipation factor (Df) of the dielectric substrate (i.e., composite resin). Transmission loss can be reduced when one or both of Dk and Df of the composite resin are lowered. Therefore, in many applications, it is critical to choose a dielectric substrate having both a low dielectric constant and low dissipation factor in order to provide the signal transmission speeds required for state-of-the-art information processing.
Lowering the dielectric dissipation factor can have a substantial effect on the performance of printed circuit boards in high speed applications. Thus, manufacturers of, e.g., high quality internet servers and RF boards require dielectric substrates made of composite resins with a Df (i.e., loss tangent) of 0.006 or less, preferably 0.005 or less, at 10 GHz. This property allows for the fabrication of printed circuit boards that can be used for, e.g., high-frequency radio antennas and high end server applications. Additionally, manufacturers of broadband devices desire a substrate with a loss tangent that is unchanged over a wide frequency range. Accordingly, it is desirable to provide a composite resin that not only has a low loss tangent at 10 GHz, but that also has a similarly low and relatively constant loss tangent at lower frequencies, e.g., 5 GHz and 1 GHz.”
[Qiang et al, US Patent 8,258,216 (9/4/2012)]
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Roger D. Corneliussen
Maro Polymer Links
Tel: 610 363 9920
Fax: 610 363 9921
Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
* Date of latest addition; date of first entry is 6/27/2012.