What if PCBs were really printed?
Printed-circuit boards (PCBs) are the foundation of many of our electronic products. These copper-clad boards – often but not always using glass-epoxy FR-4 substrate, but increasing more exotic materials for the gigahertz spectrum – are both the structural support and interconnect medium we rely on to knit together active and passive components and their interconnects.
The first PC boards were developed during WWII, using a ceramic substrate with conductive traces screened onto the surface; the leaded components were inserted and soldered into drilled holes in the ceramic. During the late 1970s and early 1980s, the PCB as we know it today came into production, again with through-hole components. Hard to believe but true: there were TV ads in the early days of PCBs from a major TV vendor (was it RCA? Or Motorola?) that claimed the superiority of point-to-point, hand-wired "craftsmanship" in their TVs to the new-fangled PCB approach; but as transistors and ICs came into general use, hand wiring became a non-starter.
The use of PCBs with surface-mount technology (SMT) started in the 1990s, and lead pitch and track widths have been shrinking ever since, now down to a few mils (1000s of an inch). Double-sided and multilayer boards, some with over a dozen layers, added to the versatility. Ironically, many low-end consumer products, such as the mouse, often use low-cost phenolic as their substrate in single-sided layout with liberal use of jumpers to avoid the need for circuits on the bottom side; the boards are punched rather than drilled, which is quick and further lowers the cost.
Note that there is really nothing really "printed" about today’s PC boards. Most are made using a subtractive process, where copper is chemically etched from unprotected areas; some use an additive process where copper is plated onto designated areas. There are also boards that are made using fine-dimension mechanical or laser-based milling (see the fascinating machines from LPKF, for example).
But what if we could really "print" or lay the conductive traces onto the substrate? Wouldn’t that allow for fast set-up, board-to-board flexibility, and low-cost prototyping?
That’s why I was intrigued when I read about the Kickstarter efforts of Canada/China-based hardware startup Voltera to develop a low-cost printed circuit machine. It uses a silver nanoparticle conductive ink and places traces on a standard FR-4 board; there’s even a way to place an insulating layer on top and then print another layer, for the electrical equivalent of a two-sided board. The machine is available for pre-order at around $2000 and will hopefully ship in 2016.
This printed-circuit board machine from Voltera on Kickstarter could be a convenient way to roll your own boards with flexibility and at low cost, although with some likely limitations.
While this unit cannot produce 20-layer boards with super-tight pitch, I think even a basic non-chemical, do-it-yourself PC-board "printer" would be useful for verifying a sub-circuit’s performance, evaluation of circuit designs, and more. Also keep in mind that not every design is a GHz-range RF product where tiny changes in component placement and track routing between the prototype units and final design will affect performance; there are many projects with lower-frequency operation or no RF functions, or where the RF role will filled by a module or IC which drops onto board.
I think it is great to have a unit which lets experimenters, hobbyists, and school programs make their own boards and get involved in circuit design. Too often, IMO, hands-on circuit engineering is frustrating due to the challenges of getting prototyping beyond simple "protoboards," along with today’s super-tiny discrete components and large IC with dozens of leads around and even under the package. As a result, much of the engineering experience is reduced to writing code for apps or programming assembled, purchased hardware (although companies such as adafruit do have some very nice kits and project material).
What’s your view on DIY, non-chemical PC boards? Would one be useful to you, at a reasonable price, even if it could not do the latest PC-board track spacing, IC lead pitches, or complex multilayer fabrications?
Bill Schweber, is an electronics engineer and author who has written for EE Times, was analog editor at EDN and prior to that worked in marketing communications for Analog Design and was also editor of its technical journal.
This article first appeared on EE Times’ Planet Analog website.
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