Very small holes can always be drilled, but it's best to use 0.6 or larger for via's. Smaller sizes force us to reduce the number of boards in a drilling stack, which increases our production cost. This is either due to inability of the drills to clear the debris or excessive wandering as the drill flexes to find the easiest route though the stack. 

Large holes above 5mm are often routed but at only a small extra cost to the std drilling price. Whereas the dimensional tolerance of a drilled hole is very good, small variations in size are usual with routed holes. To avoid problems larger holes are normally treated as  +.1mm -0mm 

The main size price break point for routing is 1.6mm below which the price starts to climb. Again it's the problems in clearing the debris and the shorter life span of the smaller routers. 

Where a larger volume of conventional PCBs are to be routed yet again the laminate make a big difference. The std FR4 grade is very abrasive and quickly degrades the tool bits if the circuits can be made on a softer material cost savings will result.

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 Rev  27 June 2024

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