From Microns to Nano

PCB designs will soon enter a new dimension in miniaturization.

Our industry has always been about creating cutting-edge, next-generation technology. Over decades this has been accomplished by striving to pack more capability in less space. The electronics industry, and printed circuits in particular, has accomplished this more often than not without specific definitions to either strive for, or be hindered by.

Such examples can be found by looking at the definitions, per Oxford Languages, for five simple words that have been used over the decades in our technologically driven businesses:

• Normal – defined as “usual, typical or expected”
• Small – defined as “of a size that is less than normal”
• Compact – defined as “closely and neatly packaged together; dense”
• Miniature – defined as “if a much smaller size than normal”
• Dense – “closely compacted in substance.”

Clearly, the definition of each word has, shall we say, an open interpretation as it relates to technology, dimensions and tolerances! And yet, over the decades, engineers speaking and working on next-generation projects have had more than a good idea of what, at that point in time, each word meant.

In the early 1990s, if you were fabricating printed circuit boards, “normal” was defined as a board with 7-mil lines and spaces. “Small” referred to something along the lines of 5-mil lines and spaces. “Compact” would have included a panel of circuit boards that were V-scored to get as many as possible on the panel. “Miniature” was a dream: lines and spaces of less than 5 mils. And “dense” referred to how thin the combined layers on a multilayer circuit board can be.

That was then, now is now. New words are entering the vocabulary of designers and fabricators. The days of using terms with open-ended interpretations when defining the goal of getting more capability into less space has finally given way to the use of words with more specific dimensional definitions.

“Micron” has been used for years in the discussion of dimensions and tolerances sought when designing and fabricating circuit boards. Micron is a metric unit of length equal to one millionth of a meter. Developing the processes and materials to support micron technologies’ ultra-minute dimensions is a formidable task that is still underway, but it has yielded highly successful results.

Today, micron plating thicknesses and the ability to plate in microns is common. IPC standards define acceptable plating thicknesses in microns. Suppliers of PCB materials use microns in their specifications. Imagining the ability to plate or image in microns was once a dream. Today, while still cutting-edge, holding dimensions and tolerances in microns is commonplace, and micron technologies are standard in the greater electronics industry. 

Another word gaining traction in our industry is “nano.” “Nano” is a short for “nanotechnology,” which is a metric unit of length equal to one billionth of a meter. If producing printed circuit boards with dimensions in microns is cutting-edge, producing circuit boards with nano dimensions is nothing less than bleeding edge! But as intimidating as the thought of nano dimensions may be, developing processes and materials is how our industry, over and over, has been able to develop bleeding-edge technologies that eventually become industry standard.

If micron is today considered “normal,” then new processes and materials necessary to establish nanotechnology within the printed circuit board industry will undoubtedly go through various iterations and phases of research, development and refinement. These combined efforts will be more interesting, as well as more challenging, than those of the past, in large part because the size – the actual dimensions – have far exceeded the ability for the unaided human eye to observe.

Equally, some of the products in which nanotechnologies will be utilized may also be too small for the human eye to see unaided. As dimensions shrink, so can the packages they go into.

So here we are again, as we have been countless times over the decades; an industry working on the next challenge. This time it is taking the current “normal” of micron technology, and by diligently working to transition processes and materials, moving from “small” to “compact,” “miniature” to “dense,” until we achieve the next baseline for “normal,” which will shortly be nanotechnologies. Onto the next great challenge, and repeat.

Peter Bigelow is president of FTG Circuits Haverhill; (imipcb.com); pbigelow@imipcb.com. His column appears monthly.