Printed Circuit Design & Fab Online Magazine - Current Issue

Designer’s Notebook

DfM means design for money. If it can’t be built, that’s a waste.

Great ideas come together with great timing; what’s left is great execution. Flipping the switch that sets the factory in motion causes a few pain points. These “opportunities for improvement” will dictate your agenda down to the minute with all the little things that go wrong. Let’s say there is a factory downstairs from you. Further, the factory is doing slow and laborious rework on old printed circuit boards, aka PCBs. There is a solution! New PCBs. We’re going from P0 (zero) to P1 (one). That’s where we, the designers, come in.

At new PCB time, the first order of business is improving the electronics in some way. The fix could be better performance, lower cost, higher reliability and, in some cases, all the above. Venturing into wireless technology and gaining FCC approval to play in its allocated spectrum is no slam dunk. Beefing up the power grid is a typical step. A good power distribution network has been known to cover for otherwise iffy routing. Every engineer will have some considerations carried forward.

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Why you should be mindful of long parallel routing situations.

It was a warm Saturday morning last August when we decided to visit my favorite Swedish flatpack furniture store. We, of course, means me tagging along with my spouse as she chose some stuff to seal the back-to-school deals. (One more year!) We weren’t the only ones with that plan, so it was fortunate I knew the parking lot well.

For the uninitiated, the store layout – including the garage – is a giant maze of hallways. You pass by little rooms of staged furniture on the top floor, then another habitrail running past an assortment of sundry household items on the floor between that one and the parking level. It is supposed to be a treasure hunt, with cheap, bland food at either end.

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Don’t be afraid of the ground.

Doing special things with a circuit pattern is a hallmark of analog design. All the important signals on the board added together are equal in importance to one net; that net is the ground net. Every active component will have at least one of its pins tied to ground. An RF device could use any number of voltages and will likely want a dedicated power supply for each voltage required. Characteristic impedance relies on a ground plane or two.

Faster digital circuits start to behave like their analog counterparts. The typical routing rules involve fanning out the surface mount pins with short segments and doing the main course of the routing on an innerlayer. An elegant placement could make it possible for the bus of related traces to run entirely on the outer layers.

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Model-based enterprise initiatives often ignore electronics.

Reams of presentations and data support efficiencies gained by digital thread initiatives, but much of the dialogue is driven by mechanical design processes with little regard for the electronics components of a product being developed, deployed and maintained. To review some of these basic concepts, see FIGURE 1, which starts with model-based design as a foundation of a model-based enterprise. This enables a robust digital thread that feeds into Industry 4.0 with smart factory initiatives under a framework of communication and collaboration that is defined as intelligent information management (IIM).

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