In Altium (and I suspect in other commercial tools) there are two different types of pad behavior: when creating/editing/viewing footprints, and when working on the board.
When editing footprints, you only have the concept of top, middle, and bottom layers. You don't know the full board stackup. So, for a PTH pad, you can set what you want to happen on *all* inner layers, and it can be different from the top and bottom layers if you'd like. Altium lets you have different shapes for each of these (maybe you want a square pad on the top for identification purposes, but round on inner layers). Altium doesn't let you do this for SMD pads, I guess because it doesn't make sense to pre-assign a SMD pad to a particular inner layer in the footprint editor when you don't know on what board stackup it will be used. When you place a footprint or free pad on the board, you can edit that pad in the context of the board. This means things like moving a SMD pad to a particular inner layer, or removing the pad from one or all inner layers on a PTH pad. There is a toggle for stackup mode in Altium: Simple, Top-Middle-Bottom, and Full Stack. These give you one, three, or N sets of pad size/shape options respectively, where N is your PCB copper layer count. Some SMD pads require different shapes for paste layers (I've never seen mask be anything other than an offset, positive or negative, from the copper shape) On Thu, Jun 11, 2020 at 10:54 AM Jeff Young <j...@rokeby.ie> wrote: > > I had been assuming that you could define a separate shape for each layer. > Full flexibility, but time-consuming to edit (even with commands such as > “push current layer to other layers”). > > Most users are looking to route traces on inner layers between tight pads. > This is commonly done with the definition of a “capture pad”. The constraint > on inner layers that have connecting tracks is simply not to have a butt > joint between the track and the plated hole. A capture pad is therefore a > circular pad with an annulus width of the drill wander plus 1 or 2 mils; > other capture pad shapes get you nothing more. > > There were also a few requests for SMD pads on a single inner layer (or > perhaps multiple) — but importantly not for different shapes on different > layers. > > So one could imagine allowing the pad shape to be placed on any number of > layers, and a capture annulus width for any other connected layers. While it > doesn’t have same flexibility, it would be a lot easier to edit. > > Another possible complication is wanting a different shape for mask (or > paste) layers. Is this ever required? > > Thoughts? > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : kicad-developers@lists.launchpad.net > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : kicad-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
