The Rise, Fall and Rise of Wires

In the world of electronics, the printed circuit board (PCB) has ruled the roost for decades, and that’s a good thing. The alternatives are inconveniently large.

Old Technology

In my younger days, I had visions of joining the Navy, so I joined the cadets. I was privileged to be shown around stations, installations and ships of Her Majesty’s forces, and in the 80s much of the equipment being used was of 1960s vintage. A radar system back then would require a fair-sized building to provide it with a home. The technology was dominated by valves and wiring. Instead of PCBs, the system used huge racks filled with wire-wrap connectors. The hundreds of meters of wiring needed to join devices together takes up a lot of room.

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Radar from the 60s
Image: Subterranea Britannica​

With the adoption of PCBs across the electronics industry, the wire wrap connector has all but disappeared. PCBs are smaller in size and quicker to construct. The smartphone of today would be hard to imagine without PCBs, surface mount technology or automated assembly machines. You might be forgiven for thinking that the use of wires in this kind of installation is a thing of the past.

The Future is Data

However, there is a trend that is bringing wires back from their exile, and that trend is data. The commodity of the future is going to be data. Someone told me recently that the demand for data will grow so much in the next 5 years that one-fifth of all the energy created by mankind will be used in data centers. That is a frightening number, but it is not hard to believe. Just consider billions of devices, connected to the internet, all trying to communicate with each other.

Unfortunately, mankind is an impatient bunch. Not only will we expect access to all of this data, but we will also be expecting it instantly. No-one likes to wait for a slow internet connection, and consumers will not tolerate slower speeds in the future. We want more, and we want it now. The communications infrastructure will have to keep up.

The industry is working hard to rise to the challenge. Companies are working on silicon that can generate signals up to 112 Gigabits per second. That’s a big number, so let’s try to put it into context…

According to their own website, The British Library holds some 170 million books and publications, held on nearly 500 miles of shelves. 10 yards of books on a shelf represents about 1 Gigabyte of data, so my calculation says that the library holds nearly 90 Terabytes of printed information. It would take nearly 20,000 normal, single-sided DVDs to contain it all, but at 112 Gigabits per second, the entire library could be transmitted in less than 2 hours.

That’s fast.

Wires Make a Return

What has this got to do with wires? Well, printed circuit boards (PCB) are very good at some things. They are small and fairly easy to make in lots of complicated shapes. However, the physical design of a PCB does not lend itself to transmitting data at high speeds. All those parallel layers and side-by-side tracks mean that high-speed signals sent through a PCB will lose power very quickly. At 13 GHz, a PCB might be introducing losses of 45dB in less than a meter. When consumers are demanding so much data so quickly, performance like this will risk unacceptable loss of signal integrity.

Cables are coming to the rescue. Using custom-made twin-axial cables , cables can deliver losses of only 10% when compared to the PCB. When looking at connecting high-speed silicon to other devices, this can make all the difference.

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Samtec's Flyover® Technology
Image: Samtec​

There are connector manufacturers who are embracing this new solution to the high-speed problem. One example is US company Samtec, who have developed their Flyover® technology to remove the traces from lossy PCBs and improve signal integrity. By taking the signals away from the PCB and transmitting them over dedicated cabled connections, modern designs can be made to handle the rocket-ship speeds that are required.

High-speed signals and the data they carry are the currency of the future. The networks that carry this data will need to be ready for it, and thanks to folks like the engineers at Samtec, the next few years will be the quickest ever! Take a look at technology and find out what you need to do to be ready too.
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