Not long ago, I answered Editor Andy Shaughnessy’s “Whose Fault is That Bad Board?” survey. When I answered the first question (“If a board fails in the field, whose fault is it, typically?”), I was disappointed that he used radio buttons instead of check boxes. I did not want to blame only the designer for every bad board in the world. Did Andy want me to name the ones who are most often blamed?
Who are these designers? PCB designers are like magicians; they can materialize an idea from a piece of paper, and many of them are also the creators of the product. And designers create many jobs. Their projects may have gaps, but I would not blame designers for all the bad boards. They are the first to be blamed because they take the first step in the product’s life cycle. They can make mistakes too, but sometimes their fault is having too much confidence in the people who follow up on their work.
I know an American entrepreneur who went to Poland to open a PCB design bureau. He found painters and architects for hire, but not many engineers; he was very pleased to find many electronic engineers here in Romania. But are all engineers qualified to be great PCB designers?
Years ago, I held a position in an EMS company where projects were analysed before sending them to be produced on the assembly lines. We found that even some of the best and most innovative circuits could not be manufactured. Why? Because the PCB designer, an electronic engineer, was not acquainted with the fabrication process. He had no idea about technological requirements necessary for electronic production.
Here is a funny story: I know of one designer who learned, finally, the importance of the thermal relief pad for heat restriction during reflow for a good soldering. His response? “Oh, was that what they were for? And to think I worked so much to remove them!”
The CAD program itself had introduced thermal bridges where the pads were linked to large copper areas, but the designer’s eye did not like the way they looked. This was a happy case because the designer had presented the project before sending the order for fabrication. But other times, matters were much more serious. When a board came in for assembly, it was necessary to manually heat the pad and the component with two soldering irons. Some designers understood this aspect (especially after they were walked through the factory to see the whole technological process), while others even got angry, yelling, “I will send the project to China and they will do it!” Yes, they will, but they will fabricate exactly what was sent, including the design errors. This was the case once when a designer forgot to send an Excellon file; the printed circuit board was manufactured without the holes for the 40-pin DIL package of a microcontroller.
Some designers will gladly fit the schematic on the entire sheet. One designer learned that, with the right modifications, the area of the printed circuit board could be reduced, and thus the cost of the board could be reduced. He replied, “Oh, it is for the Army, and they have enough money not to worry for the size of the board!”
To read this entire article, which appeared in the August 2017 issue of The PCB Design Magazine, click here.