More than ten years ago, I was already looking forward to it. No more copper in your computer, but glass. Unfortunately, in 2025 it is still not a reality at the office or at home. A shame.
Whether it is your smartphone or even your desktop computer, the circuit boards inside use thin layers of copper. Like highways for all the data that has to travel through the entire machine. From one chip to the next, and eventually to your screen.
But this has a well-known drawback: the so-called skin effect. To explain it, we need to go back to basics. And I don’t mean ones and zeros; no, I mean the absolute basics: physics. Because over all those copper highways in your device, electrons are racing.
Some people may know Moore’s Law: the number of transistors on a chip doubles roughly every two years. This means the processing power of processors increases exponentially. But somewhere we seem to have hit a wall. And that is logical.
The skin effect is the phenomenon where alternating current (such as in digital signals) moves mainly on the surface of a conductor. In other words, at higher frequencies, electrons do not travel through the full thickness of the copper trace, but mainly along the outside. If the current is too fast or too high, the effective resistance increases and the signal can distort. So it is not literally true that electrons “fly off the track”, but you can use the image of flying electrons as a metaphor for signal loss or interference.
Sometimes you want this to happen. Antennas, for example, rely on the skin effect. An antenna wants to transmit signals; in doing so, it may seem as if the electrons leave the antenna, a copper rod, and fly out into the world. This is how we can receive radio at home, if you still have an FM radio at least. To be technically precise, the electrons themselves hardly move; it is the electromagnetic field that spreads and carries the signal beyond the antenna. But I digress from my point.
For our insatiable thirst for faster computers, we need electrons to reach their destination neatly, elsewhere in the same device.
And so we need glass. Because in glass, information can travel at the speed of light. That is the ultimate dream. As far as we know, no information can travel faster than light. That speed, roughly 299,792 kilometers per second, is an impressive goal. To put it in perspective: in copper, the signaling speed is much lower, around 200,000 kilometers per second in practical conditions (depending on frequency and the dielectric properties of the material). Above that, signal loss, interference, and heat development occur. We wanted a faster PC, not a heater.
We are waiting for optical transmitters (lasers) and receivers that are small enough to fit inside chips. When that happens, the copper traces on PCBs can be replaced with fiber optics. In an ideal world, a chip would not even need to convert the signal, and it would operate entirely optically inside as well.
We are a bit stuck in the new “copper age”, it seems. But let’s look forward to the next step, so we can make big leaps again.