Hello Ofer,

From your comments I sense that you are aware that one should be careful 
about getting too wedded to the concept of aspect ratio. 10:1 may be too high an 
aspect ration for lower thickness boards as well. 

There are practical matters alluded to in Brian's comments and that I know 
Werner knows well. You can drill an 75µm hole in a 750µm board (10:1) but you 
won't get the commonly specified 25µm of copper on the entire hole wall. The 
hole will likely close on the top before the wall in the center is plated using 
standard electroplating practices. Additive processing will get you closer but 
it will take a long time. 

Also unstated thus far the dialogue (but I am sure understood by all) is that 
copper plating differs in quality based on the chemistry, controls and 
process parameters. The concepts discussed so far are based on an "all things being 
equal" analysis relative to copper. Once the theoretical is nailed down the 
practical must also be dealt with. 

Best regards, 
Joe     

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