> You can no longer connect to vias with thermal relief, a pet gripe of
mine,
> if that's what you're trying to do. They broke that a while back.
> There is a menu option to convert vias to free pads which will then permit
> thermal relief connections. The only drawback with this method is that it
> will leave the t.h.pads in place if you have the Auto Remove Loops option
> enabled and the connecting traces are re-routed / ripped up. It also mucks
> up your board reports.
> If you are getting no connection at all, my appologies for being off
track.
>
> Mick Beavis
In normal circumstances, I would have thought that there would not be too
much merit in connecting vias to either polygons or Power Plane layers with
a thermal relief pattern, as vias do not normally have anything soldered to
them (which is the normal reason for using thermal relief patterns).
But I decided to check for myself what happens to vias in Protel 99 SE, SP6.
My finding was that for connections to Power Plane layers, vias follow the
Board-scope Design Rule (either Direct Connect or Relief Connect) *if* no
Design Rules specific to vias are defined. But, it is possible to set a
distinct Design Rule, specific to vias, which is then followed by
(qualifying) vias.
So if the Board-scope Rule is for Relief Connect, and no separate Rule is
defined for vias, all connections (pads and vias) will be Relief Connect. It
is possible to leave pads Relief Connect, but to change vias to Direct
Connect, by adding an appropriate Rule which is specific to vias.
Conversely, if the Board-scope Rule is for Direct Connect instead, and no
separate Rule is defined for vias, all connections (pads and vias) will be
Direct Connect. And it is possible to leave pads Direct Connect, but to
change vias to Relief Connect, by adding an appropriate Rule which is
specific to vias.
This is the situation for connections to Power Plane layers, and that is how
it *should* be implemented. But for *polygons* (on standard copper layers),
vias are *always* Direct Connect, and regardless of what via-specific Design
Rules are defined. Although I re-iterate that I can't see too much merit in
vias being Relief Connected to polygons, the inability to implement this
(short of resorting to round-about methods) can still be regarded as a bug.
Has this ever been reported previously?
In some ways, I can understand why Protel have changed their software so
that vias are direct connected to polygons *by default* (regardless of what
the Board-scope Design Rule specifies), as that is probably what most users
usually want. But even with such an implementation, it *should* still be
possible to add a Design Rule which changes that behaviour.
However, I am of two minds on actually implementing things that way though.
If the updated implementation permitted vias to be relief connected *when so
desired*, but with the *default* setting being direct connect (matching what
most users probably usually want), this "way of doing things" would differ
from that used by *other* types of Design Rules. As such, that could well
increase the probability of bugs in succeeding versions of Protel.
As such, my personal preference leans towards restoring what I think was the
implementation with previous Service Packs, in which vias were connected in
the manner determined by the Design Rules, and *without* any default
settings (for vias) which had (total) dominance over any Design Rules
(Board-scope or otherwise). However, what could make things more
user-friendly is providing *two* initial/provided-by-default Design Rules
for polygon connections. One of these would be a Board-scope Design Rule
which would specify Relief Connect. The other would apply to *all* vias,
and would specify Direct Connect. That way, vias would be Direct Connect
*unless* the user deleted or disabled the associated (provided-by-default)
Design Rule, while the ability to do that (i.e. to delete or disable that
Design Rule) would permit users to have Relief Connect for vias, when/if
that is required; all the while, how polygons connect to pads and vias would
be determined by Design Rules in a totally conventional manner, and with
*no* differences in implementation.
Sorry for being long-winded, but I see this as being the way forward...
Regards,
Geoff Harland.
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