At today’s speeds it takes more than a clever circuit design to retrieve
clear signals. You also need intimate details of the passive materials
carrying the signals.
To date FR4 has been the work horse for printed circuit boards. But for
years I’ve heard about a range of more exotic and costly materials that
can deliver better characteristics for a price. The word I hear is
Panasonic's Megatron-6 is looking pretty good.
My question for DesignCon is whether there is anything beyond FR4 likely to go into mainstream use anytime soon. My go-to guy for that sort of question is consultant Lee Ritchey who will present a paper comparing seven laminate materials. Intel engineers will give a similar paper comparing FR4 to some alternatives. And a team of Dupont, IBM and Molex will talk about their work in flex circuits.
I noticed your comments about materials so here are some thoughts: the industry is moving beyond just using conventional FR4. Most of the
change is geared toward the raw materials, like resin, glass fabrics and
copper, as well as a focus on hybrid constructions that utilize multiple
types of laminates in the same PCB. Spread glass is becoming popular again because of its more consistent rates of the signal speeds. We are also looking at material combinations that may function differently. Some layers of an interconnect may require high-speed materials, while other parts might only require FR4, or you may have a combination of materials on different layers. Another reason for the move to hybrid constructions is to lower costs, as high-speed laminates can reach 15x the cost of standard materials. Additionally, there is usually much more material used on a higher layer board. Another important change is the
move to lead free-assemblies in order to conform with international
standards for eco-friendly products. Dale Kersten, Vice President Operations, Global Engineering, Sanmina