On 1/22/07, David VanHorn wrote: > > > > > > The many PCB manufacturers I've used over the past 25 years vary greatly > > in > > plating thickness. So I always provide the finished hole size and let the > > PCB guys figure out what size hole to drill before plating. This has the > > added benefit of not having to change the design files every time the > > plating process gets improved or the vendor is changed. I put a note on > > the > > drill drawing that states the sizes are "finished hole sizes (after > > plating)". If I was designing a PCB where current carrying capacity was > > important, I would also add a note to the drill drawing on minimum plating > > thickness requirements and then also put a note in the readme file. > > > That's really the only way to fly.. Let them worry about their process > variables, just specify the end result, and verify that they did achieve it. > > I also put notes with the job files that the gerbers are not to be altered > by them other than in panelization. > I've seen too many instances of them plopping a cute little logo into > "unused space" that was important to remain unused, like in stripline/RF > designs, or high voltage sections. There are deepest manufacturing problems David. At really large density (small via rings) they must add tear drops (if there are not already there), and struggle with laser/mechanical drilled holes like 5-6mil (0.125-0.15mm) and routes/clearances below 4 mil (0.10mm) where any acid trap becomes a mess. Only a few houses are able to do this even they claim it's manufacturable and they handle the technology. The best way is to do yourself the panelisation for such restrictive designs. Unfortunately sometimes the PCB houses does not gave you enough informations to adjust your design acordingly with their technology. greetings, Vasile -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist