9 Replies Latest reply on Nov 29, 2010 9:57 AM by cliffh

    add short copper stubs to pad?

    johnbeale

      I have an existing flex circuit layout in PADS. The flex fab house suggests adding short copper stub lines from each pad that extend under the coverlay opening, to help anchor the pad physically on the flex cable. For an example of what they want, see the two pads at the center of the image below. Each pad has three short red "stub" copper ears that extend under the green coverlay aperture.

       

      The obvious way to do this in PADS is to start a new copper route on the pad, that ends without making a connection, but I don't seem to be able to generate such a route. As soon as I stop without connecting to another pad or net, the entire trace goes away. I could do a separate block copper area or copper pour and assign that to the net, but that seems slow and clumsy. What is the recommended approach?

       

      stub-pads.png

        • 1. Re: add short copper stubs to pad?
          george_defond

          John:

            Before you select anything just start typing the following "end no via". This will set your end mode when doing partial routing. You can start to route a connection, just off the edge of the pad, then hold down the CTRL key and click with the mouse. PADS will drop the trace and you'll have your stub.

           

          Best wishes,

          George

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          • 2. Re: add short copper stubs to pad?
            johnbeale

            Thank you George, that got me a start. Following your instructions, I can now create one short trace exiting a pad and stopping with no further connection.

             

            However I want to generate more than one such trace from each pad, as shown in the illustration in my first post.  It appears that PADS does not allow me to do this more than once. When I try to repeat the procedure to generate a second such trace from a different corner of the same pad, the trace simply disappears after CTRL-LeftClick.  I confirmed that I am still in "End No Via" mode.  Also, for some reason, the technique appears to work (once) on some pads, and not at all on other pads.  Is there any way to get around this, and create several stubs on every pad?

             

            EDIT: It is possible that there is a tiny, hidden stub already on some pads (entirely within the pad boundary, hence not visible) preventing me from adding a stub on some pads. Note, after closing and re-opening the .pcb file in PADS, I notice that it works better: I can now add three stubs on one pad, and two stubs on another, but adding the third on this pad causes the first two to disappear (!)  The behavior does not seem consistent.

             

            I am using PADS Layout 2007.4  if that matters.

            • 3. Re: add short copper stubs to pad?
              David Ricketts

              My recommended approach is to use copper. It's not as clumsy as you may believe, especially after a little practice, as there are many ways to implement it. I would use a simple copper circle of an appropriate diameter, place the center on the edge of the pad or just inside, and copy it everywhere you need an anchor point.

               

              1. Select Net, and there's an Add Copper Area or Add Copper Pour command on the context menu.

               

              2. Draw or copy a copper polygon, and you can use the Assign Net by Click option in Properties to assign or re-assign the Net. A copied polygon retains the original net name association.

               

              3. You could use solid copper instead of a pour, as it doesn't require a separate pour command, but it would require more manual effort to fix DRC errors.

               

              4. If you use copper pours, you need to remember to Pour All before post processing, but the DRC back off would be automatic.

               

              The reason adding trace stubs doesn't work is because PADS is pin pair based. By this I mean the only valid route is between two pins. Every routing command is biased towards not making pin pair errors, even they they may sometimes occur, and a stub is definitely that. Note that even routing a loop requires a specific command.

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              • 4. Re: is it possible to construct a true circle?
                johnbeale

                Thanks David, I have come to the same conclusion.

                 

                By the way, one more question if you don't mind: is there an easy way to create a copper circle object directly?

                 

                The only way I know is to create a part (Decal / Pad Stack) with one pin that is a circular pad.  Copper objects and pours from the Drafting Toolbar always seem to be polygons. I can pull an arc on any side to make an approximation to a circle, but if (for example) I start with a triangle and then for each side, I select Drafting Edge Properties and make each side an arc with the exact same (XC,YC) center point and (R) radius, and radius Delta Angle that exactly adds up to a 360 degree circle, the entire object just disappears as soon as it becomes a circle.  If I offset the center point, radius, or delta angle, I can make  "almost circles" and football-shaped things, but apparently not a true circle (?)

                 

                EDIT: One more observation: if I select several copper objects at once and attempt to "Assign Net by Click" to all of them, I get FATAL RUNTIME ERROR and an immediate crash... sigh.

                • 5. Re: is it possible to construct a true circle?
                  george_defond

                  Yes there is. type the modeless command hc and the draw will be a circle. Type hr for a rectangle, hp for a polygon and hh for a path or line.

                   

                  George

                  • 6. Re: is it possible to construct a true circle?
                    David Ricketts

                    Short answer, yes. I see you are not familiar with the context menu. It is a command dependant sub-menu, accessible with the RMB, Right Mouse Button. Almost any command you invoke has a RMB menu with all the options available, and even some of those have their own context menu. For the various drawing commands, like 2D line, Copper, Copper Pour , etc. RMB brings up all of the shape options, like circle, rectangle or polygon. It's very powerful. The modeless commands George mentions above are keyboard shortcuts listed on this menu. A caveat: on the PCB, don't use 2D line for copper. DRC doesn't check for it.

                     

                    Another caveat, when you draw the copper shape or pour, you need to press OK to the dialog box, otherwise the new shape will not complete correctly.

                     

                    It is true you cannot select more than one shape at a time to edit it, but PADS should not crash because of it. That is an installation specific problem, as it does not happen for me.

                    • 7. selecting a circle object and moving it
                      johnbeale

                      I really appreciate the help guys! As you can probably guess, a few years ago my company just bought pads without any training class (that I know of, at least). There was telephone support, but it was such a crunch at the time I had to just jump in and try to figure things out on the fly- which I've made to work, but not always the best or efficient way obviously.

                       

                      Indeed I did not know of the sub-menu. I can now make copper circle areas, which is nice.

                       

                      Yet another question: I see that I can click in the middle of a rectanglular copper area and it becomes selected. I can click in the middle of a circle, but that does NOT select it (RMB popup menu mode chosen: "Select Anything"). I have to click on the very edge of the circle to select it, and only then it becomes highlighted.  When I try to move the circle (Control-E) it just changes the radius of the circle instead of moving it.  But not always! sometimes it does move. I cannot determine what the difference is (both selecting "Move" from the RMB menu, and also CTRL-E).

                       

                      After hitting CTRL-E twice in a row, I get FATAL RUN-TIME ERROR and a crash. Is this a known bug with PADS 2007.4 ?  I am not on a service contract, so I assume I just have to live with it.

                      • 8. Re: selecting a circle object and moving it
                        David Ricketts

                        You're selecting the line, not the shape. These are different properties of the same object. You can select a line or vertex first, RMB, and select Shape, or you can RMB to select Shapes only, and you can grab the whole object.

                         

                        There's lots of reasons for PADS to crash, and almost all of them are a combination of the PADS code and your computer setup. If there was a common bug that caused all installations to crash, those get fixed immediately. You're experiencing something specific to your installation. This is not to say PADS is not causing it, as the latest version of PADS, 9.2, is quite stable, so they must have fixed something. You can do things like increasing the amount of RAM or defragging your hard drive, and that may or may not help.

                        • 9. Re: selecting a circle
                          cliffh

                          You can select the shape by LMB and draw a rectangle that includes part of the circle.