UHDI may be the next step, but what are the true limits of miniaturization?

How big is big? How small is small?

Some things sound simple but in reality are very hard, if not impossible, to fathom. Consider space. In its most simplistic form, space is simply “up there.” Look to the sky and that is space. Of course, scientists will then expand upon that to incorporate other planets, and again expand to include the solar system that encompasses those planets that circle the sun.

Within the past 100 years, humans have traversed and viewed increasingly farther into space thanks to ever-improving technology. This exploration has identified and in some cases, made contact with, phenomena such as asteroids, comets and black holes, to name just a few. Mind-boggling as these phenomena may seem, however, it is nothing compared to the infinite vastness of space! Voyager, a spacecraft launched to explore and transmit photos to Earth from deep space, has traveled over 14.8 billion miles and has only scratched the surface of the enormity of space.

Space is so big, one cannot fully comprehend its vastness.

The technologies that have been developed and harnessed to successfully explore, document and communicate back to Earth, on the other hand, are a testimony to the importance of manufacturing small devices. From the beginning of the development and deployment of the original electromechanical devices utilized to explore space, shrinking the size of devices has been the catalyst to advancing the technology.

From electromechanical to electronics, from “cards” to “chips,” advances in miniaturization are the hallmark of industry, none more than our own printed circuit board industry. From discrete wire-to-wire interconnections to large circuits, spacing and thickness, the desire to get more functionality into smaller envelopes has evolved to today’s fine lines and microvia technology. The number of circuits per square inch has exponentially increased while the actual size of the circuit board has correspondingly grown smaller.

If something such as space can be so big that its size is no longer fathomable, can the converse be true? Can something become so small that it also is no longer fathomable?

True to Moore’s law, I must believe it unthinkable to an engineer in the early days of our industry that a circuit board or chip could possibly evolve to be as small and powerful as they are today.

Just as with space exploration, however, where the imagination may not be able to fully fathom its size, imagination can embrace the challenge of seeing how far it could go. The next wave of small is just ahead of us in ultra high-density interconnects (UHDI). This technology, still in its infancy, promises to increase circuit capacity, capability and density at least twofold. This means what is now considered small will become that much tinier in the relatively near future. As with any technology in its infancy, the relative size will become more extreme as advancements in design and manufacturing take full advantage of what can be accomplished and further shrink the package.

Which begs the question, how small can electronics technologies, and specifically printed circuit boards or interconnects, go? We don’t yet know the true limit. Creative minds have imagined designs that could only be efficient if more could be done in less space. Equally determined minds have found ways to either refine manufacturing processes or develop new processes and equipment to effectively produce more capability in smaller envelopes. Looking forward, it is easy to see that advances will be made to make circuit boards significantly smaller with the capacity and capability to do more on less real estate. Going significantly smaller appears doable and is still very intellectually and emotionally digestible.

So how small does an electronic circuit need to be before its sheer size is unfathomable? A size that, as much as you look and explore, its existence is not recognizable. We already have chip packages that can barely be seen with the naked eye. Where this ends, we are a long, long way from knowing. The paradox is that when “small” is so small that it cannot be viewed by humans, like in the exploration of space, a device is invented to bring it into focus.

As with the cosmos, no matter how big and unfathomable it can appear, creative minds will continue to explore and seek answers. Ditto, inspired engineers will continue to get more functionality from ever-smaller footprints of technology. The mantra of “what if” will propel the next idea that in turn inspires the “can do” mentality to accomplish the unthinkable. How big is big? How small is small? The answer is the same: Whatever your mind can imagine!

Peter Bigelow is president of FTG Circuits Haverhill; (imipcb.com); pbigelow@imipcb.com. His column appears monthly. He is vice chair of the UHDI & Substrates: Design to Package Forum, to be held June 5, 2024, in conjunction with PCB East in the Boston suburbs.

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