Mario,

It has been a while since I last dealt with design guidelines, but on top o=
f my memory is 7mil clearance for the hole (0.007inch /0.3mm), and a minimu=
m annular ring of 6mil (0.006inch/0.25mm) or 12mil(0.012inch/0.5mm) larger =
than the hole.

The hole clearance must be larger if you plan to use wave soldering.

The best way to confirm that would be the IPC document on through hole sold=
ering.



> On Nov 18, 2017, at 10:37 AM, Electron <electron2k4@infinito.it> wrote:
>=20
>=20
> Hello,
> some of you here have a lot of experience. What is in your opinion the
> optimal hole and pad size for TH components on a double-sided PCB, to
> help flow of solder from one side to the other?
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> And how does it change if the rheofore is round or square?
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> Is there an optimal formula to calculate min/max hole and pad sizes,
> so one can, basing on the constraints (e.g. need to pass some traces
> inbetween pads) decide in the most effective possible way the size
> of drill hole and pad?
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> Thank you.
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> Kind regards,
> Mario
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> PS: please don't tell me that CADs calculate it automatically.. I want
> to learn, too.
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> --=20
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Just my $0.02,

Jean-Paul
N1JPL




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