[PCB_FORUM] Re: Via at SMD Thru
- From: Baumstark Michael-EMB043 <M.Baumstark@xxxxxxxxxxxx>
- To: "'icu-pcb-forum@xxxxxxxxxxxxx'" <icu-pcb-forum@xxxxxxxxxxxxx>
- Date: Mon, 29 Aug 2005 10:36:59 -0400
Chris:
What you have observed may not actually be a BUG, at least in terms of
functionality. It sounds more like you are reporting the lack of rule
generation from the GUI menus. Whereas a manually constructed rule actually
does behave as you interpret the rule syntax to be defined.
As I recall from several years back from Specctra 9.01 (UNIX) days, the GUI
features (via at SMD- thru, etc.) were added primarily as a new shortcut
mechanism to faciliate via-in-pad controls as a quick switch setting, PCB wide,
instead of having to use the then and still working method to call out every
padstack and allow a specified via for via-in-pad (for our purposes this was
restricted to micro-vias only and legal just about anywhere a micro-via would
fit). It appears that you may have uncovered one of those undocumented
features, or more correctly stated, added functionality within the rules
heirarchy missing the GUI menu picks. It may have been an intentional
"oversight" to keep other GUI menus in heirarchy rules less cluttered due to
the practical application at the PCB level. (But this is very good to know and
thanks for posting your observation.) Did you actually test out the
functionality when you applied this rule to a class for fanout and/or
autorouting? It !
seems you have said so: but just double checking.
I have discovered that you can perform a number of commands on the command line
that is syntactically correct and will stack up in the rules.do log file just
fine as well as replay later on without error; however, I believe that not all
commands actually work. Mostly I stick to the GUI menus lately or at least
adhere to the syntax that can be generated from a GUI, so this observation is a
dated statement.
If you discover that this is working, it may be worthwhile to keep track of
those commands that work, AS well as those that do not, especially when there
is not a supporting GUI driven command.
I suspect that Cadence will log your "Bug" observation, but due to a number of
significant functionality enhancement requests already on queue, this one item
may be a low priority line item. So in the meantime, if it does work as
expected you can tuck it into our "Bag of tricks" as an undocumented Bonus
feature.
P.S. - I will assume that you are well versed in allowing through-hole vias
within SMD pads and in particular your design group "DFM Guidelines" will
allow them in BGA pads under certain "manufacturing" conditions?
Sincerely yours,
Michael Baumstark
Staff PCB Designer - BSEE, CID+
Motorola - Advanced Product Technology Center
-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Christopher Nunn
Sent: Wednesday, August 24, 2005 4:23 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Via at SMD Thru
Hello group,
I have uncovered what I think is a bug in SPECCTRA.
I am trying to route a BGA pin top side to a bottom side SMD component. I want
the thru via to be placed in the SMD pad. The nets are power and ground and
have been set up as CLASS POWER.
In specctra, in the GUI interface, I see a button under the
PCB/Rules/Wiring/General for "Via at SMD Thru"
The same button does not exist under CLASS/Rules/Wiring/General. HOWEVER,
when I manually type at the command line: rule class POWER (via_at_smd on
(grid off) (fit off) (thru on)) specctra understands it and does what I
intended it to do.
It seems impossible to accomplish this through the GUI interface.
Can anyone else confirm this?
Thanks,
Chris Nunn
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