What is the advantage of a 'padstack' based flow

[TheUnnamedNewbie]

So some PCB/package/EM software works with the concept of padstacks for vias; you define the via separately, and then you can place it (sometimes the definition is even done in a separate tool). What is the benefit of this over a flow like in altium, where you just place a via, and can then define all the parameters for that specific via? It just feels so much more intuitive to me. Especially since some software like APD+ doesn't seem to allow you to just place a via, you first have to define it and then add it to your DRC deck as 'allowed via' before you can place it.

[nctnico]

Think about design consistency and the ability to change all vias of a certain type at one. Very handy if it turns out you need to tweak the vias you used in a design. Another advantage is that you can have vias ready to go for certain board densities. No need to think what is the smallest via that fits, just pick it from the library.

The same goes for pads for a footprint. Multiple footprints can share the same padstacks so you can update these in one go. Having padstacks makes it much easier to have consistent footprints.

[Feynman]

Well, I would find it really strange NOT having the pad stack approach It's so much easier to define a pad stack once and never worry about it again. And, as nctnico said, it's very easy to modify multiple items and to be consistent.

Usually a CAD tool that works this way also does the same thing with track widths, text styles and so forth. One big advantage is that you can define templates where everything is pre-defined. I have a "standard" and a "high density" template, for example. The standard template focuses on low cost, i. e. having track widths and via dimensions (drill size and annular ring) and a lot of other stuff that cause no extra cost with 99% of all fabricators.

And in my CAD tool I also can change properties of a single via that has been placed already. In this case the tool just creates a new pad stack with those parameters (if there doesn't exist a pad stack that matches).

However, I never heard about defining such things in an extra tool. That would indeed be a little weird, I guess.

[nctnico]

However, I never heard about defining such things in an extra tool. That would indeed be a little weird, I guess.

Orcad Allegro has a seperate padstack editor. It does allow to create the weirdest pad shapes though by importing pieces of a drawing which then becomes a pad. It is also possible to export the padstacks to an XML file, run a modification script on them and then convert back into padstacks. This allows things like creating pads for various clearances in a highly automated workflow.

[Feynman]

Yeah, but I guess it doesn't require you to use the separate padstack editor as implied in the first post.

But you are right. Having separate (optional) tools is not unusual at all. In fact most of my land patterns are created with a third party tool (even different vendor).