On 6/10/06, Rich Graziano wrote: > In my dumb way, I thought they were all compressed to the same thickness; No way. The thickness is a matter of layer numbers and technology (ie a RF board may be totally different because the epsilon of the material determine the route impedance for the same substrate material, industrial standard FR4). With a magnifier you can easily make difference between 6 or 10 layers standard board. 10 layers have bigger thickness than 6 layers. Between 2 and 4 layers could be no difference in thikness but is viewable on cross section even without magnifier. So definitely a good eye will see difference. BTW, for old piclisters living in the US there are two natural formulas for improving the eye watch: I brite and Eyebright. Both are good but "I brite" seems to be fantastic (also is hard to found). greetings, Vasile > perhaps some imperceptible difference. Is there really an observable > difference? > ----- Original Message ----- > From: "james tornes" > To: > Sent: Saturday, June 10, 2006 6:32 AM > Subject: [EE:] Visually determining PCB layer count > > > >A guy giving a presentation to us was looking at various motherboards > > and making assesments like "this is a 4 layer board", "that one is 6 > > layers". Can someone actually differentiate with an average eye, > > between boards with 4 layers and 6 layers? Thickness of boards can > > vary a bit even in-between runs so what's the technique here? > > > > Jim > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist