X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com Date: Sat, 4 Nov 2017 14:27:19 +0100 (CET) X-X-Sender: igor2 AT igor2priv To: geda-user AT delorie DOT com X-Debug: to=geda-user AT delorie DOT com from="gedau AT igor2 DOT repo DOT hu" From: gedau AT igor2 DOT repo DOT hu Subject: Re: [geda-user] [pcb-rnd] padstacks - bbvia, call for help with bbvia vs. fabs In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Reply-To: geda-user AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: geda-user AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk (... padstack announcement continued) because a padstack already has to be able to look up its pad shape on a per layer group (physical layer) basis, it was sort of trivail to add blind/buried vias too. The hole starting layer group and ending layer group is specified in a way that is transferrable between different pad stacks. The simplest thing to describe is the all-way throuh hole (needs no extra parameter). The second simplest is a blind hole (needs one parameter). A buried hole needs 2. Following the best pcb-rnd traditions, things are not entangled: whether a padstack has a hole or not does not depend on whether it has shapes on copper or other layers. Whether a hole is plated does not depend on if it's through, blind or buried. This gives the user maximum flexibility of combining the features, even building things that we would normally regard broken constructs, like an unplated buried hole between two inner layers, with a pad on each layer. Again following the best pcb-rnd traditions, we are not to outsmart the user. We let the user do what the user finds useful. Later on we will provide DRC to warn for strange looking constructs, but it's the user's responsibility to use or abuse a feature. *** CALL FOR HELP *** now that the core started to support bbvias, I started to look after how this needs to be exported for fab houses. I found contradicting recommendations and considerations. Thus I am calling for help: if you ever sent boards including blind and/or buried vias to fab and you have actual experience on what the fab wanted, please contact me. Regards, Igor2 P.S. because of the low user demand, I originally did not plan to implement bbvia. But while doing padstacks, I figured it was very easy to add it as an elegant, integral part of padstacks. Instead of trying to duct tape them as a kludge onto the existing pinvia infrastructure, which would have been the plan without padstacks. So whenever I coded something for the shapes, I also cared a bit about bbvias. At the end, when shapes already worked, bbvia needed less than 1 hour of extra testing and bugfixing to pass the initial smoke tests.