APRIL 2024 I DESIGN007 MAGAZINE 61
Design issue: Too small vias
Manufacturing pitfall: Drill breakage/reduced throughput
Remember in "Armageddon" when Harry
Stamper (Bruce Willis) and his team were
struggling to drill through the dense metal
alloy to reach the asteroid's core? We face a
similar problem when drilling through heavy
copper circuit boards.
Typical via diameters in standard technology
PCBs bottom out at 0.008"/200 microns (for
reference, a typical human hair is 0.002"/50
micron). Given that, we may drill through one-
half and 1-ounce copper with a total PCB thick-
ness of 0.062"/1.6 mm. e copper density in
a 10-layer design half-ounce copper might be
11–22%. Meanwhile, a 10-layer design with
3-ounce copper can easily hit 0.093"/2.36 mm.
Table 8: Comparison of etching methods
Figure 8: We have developed a spacing calculator
to aid designers.
Figure 9.
