Kathy Quinlan wrote:
> As I am in Au
I'd like to be in gold, too. Oh well, I guess US dollars will have to
do... ;-)
Or maybe you have the Midas Touch? If so, that's good. Personally, I've
never known anyone who had the Midas Touch, but I've known some folks who
have the Reverse Midas Touch (everything gold they touch turns to crap)...
For Brad:
What is manufacturable depends on your fab house. Every place (except the
high volume super cheap fabs) should be able to do 18 mil hole with no
price premium. Some places go down to 13 mil with no premium. As far as
relationship to track widths, the effective width of the conductive
material in the via is the via diameter * pi. So, a 13 mil via has an
equivalent track width of 13 * 3.14 = 41 mil. That's wider than your
tracks, so there should be no problems with current carrying capacity. As
far as pad size, the IPC rules (can't remember which one) state there
should be a minimum of 2 mil annular ring around the hole. You also need
to account for misalignment of the drilled holes, due to drill machine
tolerances. Typically this is 5 mils. Therefore, your annular ring as
designed should be at least 7 mils. And so, the via pad diameter ends up
14 mils larger than the hole diameter. For example, a 32 mil via pad with
a 18 mil hole.
Best regards,
Ivan Baggett
Bagotronix Inc.
website: www.bagotronix.com
Kathy Quinlan wrote:
Brad Kosiance wrote:
Any recommendations for via/pad size for 10mil tracks?
I have a dense PCB and require the smallest via/pad size that won't
violate
manufacturability of the PCBs.
The signal lines are low voltage and low current.
I assume there is a rule of thumb for 10mil, 20mil, 30mil. track widths?
Thanks,
Brad.
I am sure there is an IPC document, but I just use the biggest I can fit
without going bellow .6mm, but it all depends on what your PCB company
can reliably do .
As I am in Au I do not use IPC, as it is expensive and not stocked in
any of my local unis or tech librarys.
Regards,
Kat.
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