>William, some board manufacturing houses are able to manufacture
>class 3 PCB with 5 layer stacked microvia, some others can't
>manufacture only with dificulty two layer PCB at real density...
>so it's not a good answer. :)

But stacked microvia would be a specialist area, and if you require that, 
then you are building products that are using BGA chips and are into cost 
areas where you would go to a "full spec" board house anyway for prototype 
PCBs, and you are probably needing specialist substrates to deal with 
temperature co-efficient differences between PCB and component.

But any board house doing the normal multilayer FR4 type PCB should be able 
to do 10 thou track 10 thou space with ease, more likely 8/8 would be their 
minimum. It then becomes a matter of minimum annular rings and drill sizes 
they are prepared to use that determine component density. 

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist