We must understand that the pad diameter(s) listed
in IPC are the minimums and are more practical for
Non-soldered pad, such as vias.
Soldered pads follow a different path. For heat
dissipation/absorption a larger pad should be used.
If the component will NOT be replaced and space is
critical try using the hole diameter x 1.5
If the component might be replaced and space is critical
try using hole diameter x 1.75
If the component might be replaced and space is not
critical try using hole diameter x 2
The "might be replaced" is in-between yourself and the
engineer in considerations of board cost vs. component
replacement.
Consider this the "real world" values and considerations.
For current considerations, the remaining pad area
(pad - hole) is equal to, or larger than the trace requirements
for that layer.
For current capacity for the hole itself, find the circumference,
and the hole wall is considerable more than 1oz, (but use 1oz anyway)
and compare it to your trace width requirements.
If you need a calculator for all these functions, try
www.robertsondne.com in the resource are I have a spreadsheet calculator
(soon to be a stand-alone program)
HTH
Chris Robertson
[log in to unmask] <mailto:[log in to unmask]>
Senior Designer
Lockheed-Martin Services Inc.
4912 Research Dr.
Huntsville, AL 35805
(256) 722-2626
http://www.lmsg.lmco.com <http://www.lmsg.lmco.com/>
>
>
> Hello,
>
> Going by the tables and formula in IPC-2222, I would say that
> the minimum
> pad diameter should be
>
> 1.2 + 2x(0.15)+ 0.4 = 1.9mm
>
> (assuming that the hole size is maximum lead diameter +
> (0.25mm to 0.7mm))
>
> I would go a little larger for this sort of application to
> give more support
> for maintenance (maybe 2.5mm)
>
> regards,
>
> Phil.
>
>
> Phil Dutton C.I.D.
> Senior CAD Technician
> IPC Certified Interconnect Designer
>
> Tenix Defence Pty Ltd
> Electronic Systems Division
> Second Avenue, Technology Park,
> Mawson Lakes. SOUTH AUSTRALIA 5095
>
> ================================
> Phone (08) 8300 4400 (reception)
> (08) 8300 4481 (direct)
> Fax (08) 8349 7420
> email [log in to unmask]
> Internet Page http//www.tenix.com
> ================================
>
>
> -----Original Message-----
> From: Ahmed El-Sanhoury [mailto:[log in to unmask]]
> Sent: Monday, 20 August 2001 15:54
> To: [log in to unmask]
> Subject: [DC] reliable through hole pad diameter
>
>
> All
> When we have a passive component used in consumer electronics
> application
> (TV application single layer),which has a hole diameter
> equals to 1.2mm,what
> is the proper value of pad diameter to satisfy
> maintenance and reliability consideration.
>
> Thanks
> A.sunhoury
>
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