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While I was designing a board I thought, if we want to make a better path for the current what is the best choise? Small vias and big in numbers or fewer but with bigger hole?

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  • \$\begingroup\$ for TTL? ground? LVDS? \$\endgroup\$
    – Bageletas
    Commented Jun 15, 2017 at 20:13
  • \$\begingroup\$ For current path, power supplies. switching dc to dc or LDOs \$\endgroup\$
    – MrBit
    Commented Jun 15, 2017 at 20:14
  • \$\begingroup\$ The "trace width" of a via is essentially \$\pi\times \phi\$. So if you half the drill size (\$\phi\$), you need twice as many vias to get the same trace width. \$\endgroup\$ Commented Jun 15, 2017 at 21:00
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    \$\begingroup\$ 10*10vias packed shoulder-to-shoulder is not as good as 10*10 vias spread out so current can enter the cluster without crowding. \$\endgroup\$ Commented Jun 16, 2017 at 4:03

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This depends on what your end goal is but the answer is pretty much always use many smaller ones.

  • If you are looking for better conductivity or better heat transfer, the amount of metal you get in a via is related to the number of vias and the diameter of the drill and how much it is plated. You will always get more effective metal volume (leading to lower thermal and electrical resistance) if you use more smaller vias that are inscribed in the larger via you would have used.
  • If you want to make your PCB cheaper to manufacture, you may want to minimize the number of drill sizes the fab will have to use. You should then use multiple of the size you used throughout your board to get you're desired conductance.

The first point has diminishing returns however, and you shouldn't try to make vias as small as possible. Too small and they no longer use a drill, but a laser, and your PCB cost just quintupled.

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You better place many small via than few lager one for many reason :

  • If there is too few via on the pcb, current will tend to go to the same point and then heat the pcb. (depending of the current of course)

  • If you place more via, you have a better control on the current path across the pcb.

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    \$\begingroup\$ What about inductance? isn't it better from an inductance standpoint to have a big via as opposed to smaller ones? \$\endgroup\$
    – m4l490n
    Commented Sep 15, 2019 at 3:36
  • \$\begingroup\$ you could find that out by doing some passive circuit calculating, impedance of large via, impedance of a small via and then calculate the effective inductance of multiple parallel inductors. \$\endgroup\$
    – quantum231
    Commented Jul 19, 2023 at 20:19

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