Vasile Surducan wrote: > 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. Yes and No... You can order PCBs in a big range of thickness - if you really want. From very thin (below 0.5mm, 20mil) to very thick (beyond 3.2mm, 125mil). The normally seen 1.6mm is just a standard thickness (at least in europe). The thickness is usually not a direct result of the layer number. A multilayer PCB consists of several base material sheets and prepregs. By varying the number and thickness of these a large range of layers is possible in a large range of PCB thickness. AFAIK a 10 layer board in standard thickness should no problem at all. This might be different for exotic base materials. Florian -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist