ALBERT

Notes: "A patterned arrangement of printed wiring utilizing flexible base material with or without flexible coverlayers". The balance of this brief article will hopefully serve to help the reader understand this remarkable interconnection technology and appreciate just how widely the technology can be applied.

Notes: While promising significant improvements in the cost and performance of electronic systems, the advent of new area array packaging concepts such as the BGA and newer area array CSPs has placed significant new demands on the substrates used in their interconnection. New methods such as build-up multilayers and micro vias and co-lamination of inner layers have been described and implemented by a number of different firms in an attempt to address this important issue. One such method employs simple double-sided plated through hole flex circuits and the use of conductive pastes and bondplies to provide reliable electrical and mechanical connection between layers during a simple lamination cycle. The process, briefly described herein as a co-laminated multilayer flex, is detailed in terms of both process steps and manufacturing flow. The structure of the interconnection substrate is also modeled and examined to determine its electrical performance potential according to electrical modeling software. Finally, detailed are the performance of the structure in reliability testing and an analysis of the expected design and performance advantages that might be obtained by such type constructions in combination with BGAs and area array CSPs.

Notes: Purpose - To review the challenges confronting the electronics interconnection industry as it transitions into the gigahertz frequency range and to describe novel prospective solutions designed to circumvent the problems by means of alternative interconnection architectures while remaining within the confines of the existing manufacturing infrastructure. Design/methodology/approach - The paper has been written in a manner so as to provide first a brief review of the history of interconnections as background reference, providing access and understanding to a broader readership of the significance of the area of investigation. From there, the paper describes the problems facing electronic circuit manufactures relative to the serious matter of assuring signal integrity of high speed interconnections. It then goes on to describe a general class of prospective solutions, which can be implemented through simple architectural changes in design and manufacture. Finally, the paper describes a prototype system which was fabricated using the concepts and the first-order findings are provided. Findings - From operation of the prototype system, it was found that the concepts, relative to PCB architectural changes prescribed in the paper are capable of delivering performance levels beyond what is accepted when using traditional interconnection modalities. The 10?Gbps backplane prototype has proved capable of sending a 100?mV peak-to-peak signal a distance of 75?cm through a two wire single differential pair which pass through two industry standard connectors. The signal generated has a ~65 percent margin indicating it could go much further and determining the limits an object of future study. The modulation is standard NRZ. With only two wires there was no cross talk in the system, however, the next stage of investigation will consist of a multi-device assembly to see what cross talk effect there might be, if any. Originality/value - The chief value of the paper resides in its disclosure of novel approaches to electronic interconnection involving simple changes in circuit architectural structures which extend the signal performance limits of copper interconnections, well beyond present consensus expectations of industry. Moreover, the paper provides first experimental results of the technology in actual operation as proof of concept.