This is a great example where tools actively limit design creativity. What
possibly led to a situation where only specifying one dimension is
satisfactory? This isn't a manufacturing limitation.
It's worse when you want to do something more creative, like having vias
that have different ODs for each layer. I've done this for visual reasons
(using PCBmodE where vias are components), and I'm not sure there's a
legitimate functional reason to do that (is there?)
Cheers,
Saar.
On Tuesday, December 29, 2015, Istvan Nagy <buenoshun@xxxxxxxxx> wrote:
Jeff,
most fabs will manufacture to your ID or OD if you tell them which one you
want. The design tools like allegro and altium works best wit OD, and you
can only specify one or the other. Tools drill file formats and drill
tables only support one diameter per hole. For designing better use OD as
it helps the drc to make sure no pads drilled away and no drill to xx
clearances were violated. The wall thickness depends on the fab and the
hole size, an even the same fab will give you different numbers each time.
i think the safest is to specify OD and use worst case thin for PI while
worst case thick wall for PTH component pins.
Regards, Istvan, mobile
*** Sent from my BLU smartphone device ***
On Dec 29, 2015 11:15 AM, Jeff Loyer <jeff.loyer@xxxxxxxxxx <javascript:;>>
wrote:
(O.D.,
One thing that has bothered me forever is the ambiguity in specifying via
hole sizes. To my mind, there are instances where I might want to
carefully specify either, or both of, the outer and inner diameters
I.D., respectively) of the via âcolumnâ. But, that seems difficult (ifnot
impossible) to do with current common drill specifications (what acopper
âfinished hole sizeâ is seems to depend on context, some folks enter the
approximate drill size here). Can folks tell me how they ensure they get
the correct diameters for the following cases:
1) Signal integrity: I care about the O.D. This is going to be
(approximately) the size of actual drill used.
2) Mounting holes: I care about the O.D. This is going to be
(approximately) the size of actual drill used.
3) Press Fit connectors: I care about the I.D. This is the actual
drill size minus plating thickness.
4) Power Integrity: I care about both, I want to know the total
connecting my layers.with
What does your drill chart look like that ensures you get what you need?
Iâve used âdrill sizeâ with some tolerance plus a âfinished hole
sizeâ
its tolerance, but that seems ambiguous. At this point, I think we needto
specify a âhole diameterâ with a corresponding tolerance, and a platingeach
thickness range. While I would prefer to specify both O.D. and I.D.,
with its corresponding tolerance, Iâm told that folks in the industrywonât
know what Iâm talking about if we do it that way. What has worked bestfor
folks?to,
Also, if someone has a key contact within IPC that I should be talking
I welcome that information too (please send it to me only to limitunwanted
distribution of anyoneâs e-mail).Subject field
Thanks,
*Jeff Loyer*
Signal and Power Integrity Product Manager, Altium
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