Design for the Unknown


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Our industry loves DFx, also known as the “Design Fors.” As PCB designers, we not only design for manufacturability (DFM) but we design for assembly, reliability, cost, test, and many more factors which we like to lump together as DFx. But now, I think it’s time we embrace a new DFx: Design for the Unknown, or DFU.

I’m a firm believer that electronics development really does start with the PCB designer. I am a big fan of Stephen Covey’s The 7 Habits of Highly Effective People. I especially like to practice habit No. 2 when beginning a new PCB project: Start with the end in mind.  All too often, project teams seem to push ahead with only what is known about a project at the time, even to the point of starting the PCB layout. Proceeding on risk is a strategy that project teams use to make progress on a project despite not having all of the data or constraints. 

But proceeding on risk may only have only a small chance of working out.  When incorrect assumptions are made about a product, great amounts of resources will most certainly be wasted.  Years ago as a salaried PCB designer, I’d eagerly pushed ahead on design layouts overnight, on risk, only to be informed by a program manager the next morning that an assumed board outline or component needed to change. This affected the entire layout!  Assumed risk in these cases obliterated hundreds of healthy sleeping hours of my life that I’ll never get back. I needed a new strategy.

Thereafter, besides committing to design PCBs on an hourly basis, I sought to discipline myself to get all of the blanks filled before starting a PCB layout. I would do better at starting a PCB layout with the end in mind because “the end” is the culmination and validation of so many critical details which the design started with in the first place.

Where will this PCBA be manufactured? What types of equipment will be used? What are the potential volumes? What is the environment in which the PCBA will operate? How about that materials list—are we sure all of the parts are available?  It all begins with design and to me, designing with the end in mind means putting all of the parts together in an organized way which would facilitate meeting all of the PCB performance and manufacturing constraints.

But in the past I found myself waiting for the blanks to be filled in. The project timelines began to slip and I had not even begun placement of any of the parts. Slap! (Figuratively, of course.) I vowed to never again find myself in the awkward position of having nothing to show at the end of a project timeline. “I’m waiting on…” is never a good strategy.  Corporate management folks who report to stockholders would rather show a poorly designed PCB progress as opposed to no PCB at all.

To read this entire article, which appeared in the June 2019 issue of Design007 Magazine, click here.

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