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34 The PCB Design Magazine • August 2014 by Amit Bahl sieRRA CiRCuiTs DESIGN FoR MANUFACTURING High-Speed Networks Drive New Material Choices feature column One third of the entire human population uses the Internet, according to the Internation- al Telecommunication Union, the United Na- tions agency for information and communica- tion technologies. And access to the network is burgeoning, especially in developing countries. Not only is the sheer number of people online soaring, but demand for video services and oth- er data-intensive applications is compounding burdens on network bandwidth. Likewise, data- intensive business applications are straining the bandwidth of corporate IT infrastructures. Every sector of the electronics industry is being driven by the need to provide greater network capacity, yet improve the efficiency of network commu - nication equipment in terms of bits per second per watt. This includes the manufacturers of laminates for printed circuit boards. Cisco Systems presented a roadmap for the company's laminate requirements through 2015. The company's top priority for high-end net- work routers and line cards is a material that has half the Df of Megtron 6 at 10 GHz and requires no unusual processing during PCB fabrication, as do PTFE laminates, which are difficult to drill, desmear, and plate. It also emphasizes resistance to CAF and thermal reliability for lead-free as- sembly operations for such a material. I recently met with Leena Guila, who man- ages product marketing to OEMs and other cus- tomers for Isola, and her colleague Michael Mill- er, senior manager for OEM marketing. Close relationships with laminate suppliers are, of course, imperative for such PCB manufacturers as my company, which specializes in prototype fabrication and assembly. We had a far-ranging discussion, but concentrated on the material requirements for high-speed digital systems, es - pecially network routers and line cards. They differentiated between the properties needed for high-speed network line cards and those for router backplanes. Backplanes for carrier-class routers comprise many layers, may span distances of 30 inches