On Fri, Mar 12, 2010 at 6:25 PM, Marechiare wrote: >> All of the items that are created millions in a manufacturing >> run are, if at all possible, done on a single sided PCB >> because it saves significant money over the entire batch. > > That's somewhat debatable point, for example modern low-budget HDDs > are created in tenth of millions and have a very small double (I > believe) sided PCB. I think they could span the components to bigger > one-sided PCB, but for some reason they don't. > > Regards They are almost certainly more than two layer given the fine pitch controller and many signal traces. It's not possible to put a PQ208, for example, on a crappy single sided phenolic board. An old DVD player I just took apart (4 years old) has a large single sided board. Like what one other person just mentioned, it also has a very small multi-layer board with codec and controller chip on it (more or less.) The last circuit board I designed (6 sq. inches) was 4 layers when 2 would have worked, because trying to route it for 2 layers was taking too long. Since my time costs more money than the savings would have been, it was pointless to spend more time on it. I could fit it on a single layer board if I had about 36 inches^2, but I didn't. It's not really debatable that engineers will try to save $0.10 if they can. I'm reminded of the airline who removed a couple peanuts from their snack bags and saved a couple million a year. If that airline only had 10 passengers a day then the peanuts don't matter. -- Martin K. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist