Which PCB technologies are best suited to survive 100 years?

The Goal: Build an electronic device that will outlast everyone currently living on Earth. Looking back 100 years, few of us were here and the same will be said in the year 2124. Just reflecting on the brevity of life but we will take a century as forever.

One hundred years ago – 1924 – was the year that the Computer-Tabulating-Recording Company rebranded itself as IBM. Electric blenders, vacuum cleaners, traffic signals and television are among the inventions of the period. Two inventors of the era were leading us toward printed circuit boards though their patents were not commercially successful. Time would prove them to be quite insightful.

Looking back to move forward. PCBs finally took hold around the middle of the century while integrated circuits followed another 25 years later. My "forever" board is going to make use of these early transistor-to-transistor logic (TTL) components that predated complementary metal-oxide-semiconductor (CMOS) technology. The physically larger transistor gates and the 5V logic are a concern. Both types were used on the Voyager space probes to build the guidance and other systems. There was also a fully discrete version of the computer as a backup to the backup. I have confidence in those old Texas Instrument parts.

What history can tell us about our position in high-tech.

New Chinese restrictions on the technology, including processors, permitted in equipment procured by government agencies are the latest move in the global battle for influence in the semiconductor industry; itself a part of a larger struggle for economic power.

US-based companies have more than 46% share of the $574 billion global semiconductor market (in 2022, according to a report by Citigroup), although China is the largest end-market, representing some 31% of sales. Semiconductor exports earn more for the US economy than any other products except oil, gas and aircraft. So of course, it's important.

We have all become heavily reliant on advanced semiconductors in every aspect of life and work, driving the machines we use to get things done: the IoT applications managing our homes, businesses and infrastructures; the AI powering interactions from photography and customer service to medical decision-making; even our mobility, which is increasingly electrified, automated and connected.

Which process offers fewer steps – and less contamination?

In a perfect world, the electronics industry would have migrated to 100% SMT by now. Unfortunately, through-hole remains a required technology for some products. In particular, through-hole connectors are often preferred over their SMT counterparts due to the robust solder joints they provide.

From a Lean perspective, a requirement for mixed technology can open the door to several of the seven wastes, as it can drive the need for processes not required for a 100% SMT printed circuit board assembly (PCBA). In particular, the wastes of transport and processing can occur when separate solder processes are required for the same PCBA. The need to do multiple thermal cycles when processing via reflow and wave solder also potentially adds to the waste of defects, as it can plant the seeds for premature component failure and handling damage.

5G has great potential, but brings power challenges at the infrastructure and board levels.

5G network capacity is predicted to increase as much as 1000-fold by 2030. That's a stunning increase that can be attributed to effects such as our digital lifestyles and digital business transformation. Clearly, our dependence on online services that are available anytime, anywhere and at full speed shows no sign of abating. The effect on global energy demand could be even more stunning. The information & communications technology (ICT) industry currently consumes about 4% of the world's electricity, and this could increase to an amazing 20% with the growth of 5G networks. In absolute terms, that's equivalent to 150 quadrillion BTU per year.

Of course, 5G is huge, in scope as well as deployment. It covers low frequency bands, up to about 1GHz, although the main benefits of 5G are its ability to carry richer services that by their nature require faster data rates. These will push the limits of Frequency Range 1 (FR1) as defined by 5G standards, up to 6GHz in the FR1 range, and even higher in FR2 that extends into the millimeter-wave bands at 60-70GHz and even beyond. While services in the FR1 bands can support data rates of about 1-2Gbit/s, the higher bands are needed to support multi-gigabit data rates and latency of less than a few milliseconds.