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Need some help with Eagle and pads vs vias et al

Discussion in 'Circuit Simulation & PCB Design' started by tagaide, Feb 11, 2013.

  1. tagaide

    tagaide New Member

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    I am just rereading some of the post, the off centre hole is not required which is good.
    thanks for the tip on via pressing it does seem a bit harsh, the boards the guy made did look great though , i can share the link if i can find it in my archive.
     
  2. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Try these new files (attached).

    There are various ways to get to what looks like you have here. For the outer ring, I used the arc, rather than circle tool. I then placed 4 SMD's (3 were round). The airwares will connect to the centers of the SMD's. For the center, I used the circle and placed a via/TH pad on it. I put a t-keepout over everything. The pads have a cream layer (solder paste) that cannot be deleted, so far as I know. That could be a problem, if you later have the boards made at a commercial house.

    For the pin connections, I used "Connect Any ...." . That way you can connect any or all of the 4 pads on each ring, and you can use the ring as a connector. That is, connect to opposite sides. It will never pass DRC, because of overlaps. I named the center connection "C" and the outer ring, "R."

    I went with the arc, because I know that can be treated as signal. The circle apparently cannot be treated as signal in the library, even in 6.xx. One artifact/problem of the arc vs. signal is that I did not get the center of the rectangular pad to line up exactly with the center of the round pad on the opposite side. That can be fixed, as it is just a drawing error, but first, check these out and see if it is going in the right direction.

    You will need 6.xx.

    John

    View attachment Dome-Key_New.zip
     
  3. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Here's a revised library. I fixed alignment and the overlaps on the ring, so the only errors it throws on DRC is the overlap for the via on the central pad.

    I think I know how to fix that too, but try out this newest version and let me know how it works.

    John

    View attachment Dome-Key2.zip
     
  4. dave

    Dave New Member

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  5. tagaide

    tagaide New Member

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    will do, thanks!
     
  6. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I can get rid of the errors for the inner contact by using a polygon and copper pour, but then more errors pop up related to clearances and distances. Chose your poison.

    At this point, you have a workable device, I think. See how the milling goes. Drilling 0.016 in a pcb may not go without problems.

    John
     
  7. tagaide

    tagaide New Member

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    it will unfortunately take till monday for me to be able to upgrade to 6.x as i am still running os x 10.5. update is ordered and due to arrive on monday. Will give it a shot as soon as i get my system updated.
    Look forward to check it out!
     
  8. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    If I have any new ideas that solve all of the problems, I will post them.

    John
     
  9. tagaide

    tagaide New Member

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    Sorry it took so long to get back, please correct me if i am wrong but you are doing the following.
    place 4 X wire to mimic a quarter of a circle, (sorry for terminology mess ups) on the TOP layer.
    Then you place 3 round smd's by making them essentially square but 100% round
    Finally you add a rectangular smd on the smd on the right.

    in the center you draw a circle placed on the top layer.



    sorry for just writing what i am looking at but it seems to do what i want.

    i will try and use this and see where it takes me.

    thanks so much!
     
  10. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    That is right for the outer ring. For the inner circle, I thought I sent two versions. In one the inner circle was made with the circle tool. In the other, the inner circle was made with the polygon tool using the 90° curved arcs and copper filled. That was labeled Dome-Key2. It is still in the folder on my desktop, but I can't find it in what I sent.

    It is going to take some work to figure out what happened, and unfortunately, I have another project that needs to get done this evening. The problem with the circle tool is that the circle cannot be made part of a signal net. The polygon can be. The polygon gave more DRC errors because of clearances. Those settings could be fixed. I am not sure the overlap errors that occurred when the the circle tool was used can be fixed.

    Really, the issue for you to decide is whether you need to get rid of all DRC errors. Since this is being milled by a friend, the DRC errors may make absolutely no difference.

    John
     
  11. tagaide

    tagaide New Member

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    ok, good luck on your project, i will fiddle around. 4 smd's will be more than sufficient i think. i will scavenge the internet to resolve the issues you mentioned. you are right though, my friend will be milling but eventually i would like to produce a lot which will raise issue if the simplest checks fail.

    I will take it step by step, if and when you find the polygon solution please post it there is no immediate rush though.

    thanks
     
  12. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    You mentioned at one point that the off-center contact could be on center. For manufacturing, it may be best to keep it off center per the datasheet. At this point, is being off center still a requirement?

    To get around DRC, you will need to know minimum drill diameter and clearance that a prospective board manufacturer will want. Have you checked with your friend whether he can dill a 0.016 hole in two-sided FR4?

    John
     
  13. tagaide

    tagaide New Member

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    the off centre hole can be left out entirely,.
    i will soon receive info detailing all the cnc mill can do and cannot do.
    its professional machine not a dyi one, which hopefully will create all sorts of possibilities.
    i will keep you posted. thanks again, I keep saying this, but i moved forward really quick because of your help.
    bye,
     
  14. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Thanks. If the via can be left out, then I will get you an .lbr that doesn't fail drc, but not tonight. Sorry.

    John
     
  15. tagaide

    tagaide New Member

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    Thanks John, please note, the off center hole can be left, i am likely confusing you.
    That off center hole is there to avoid the dome creating a vacuum thus not returning to its normal state after its pressed, for the prototype i doubt this will be an issue.
    I will still need a via i think to wire the columns on the back of the board?
    Thanks again
     
  16. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I was just working on it and figured out the mess I made with file names. In brief, I had put a modified library in a different zip file, but had neglected to rename the library. That modified library was the one made with a polygon. Let me play with some options and will post then. I hadn't thought of the vacuum issue.

    So as I understand it, you need a via for contact to the bottom layer, which can be centered, but you do not need a separate hole for vacuum release.

    John
     
  17. tagaide

    tagaide New Member

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    exactly!
     
  18. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I straightened out the file system. Forget all previous libraries, unless you want the one that uses a circle. Using the circle tool will look OK, but will fail DRC in all likelihood.

    Attached is a new zipped folder named Dome-Key1. It contains a new library (Dome-Key1.lbr) and a new schematic/board with the same name. DRC gave no errors. You may need to change minimum wire width to .005 or less and minimum hole to something less than 0.016.

    This new library uses the polygon tool for the central circle. Eagle measures dimensions to the middle of the "wire," so I had to take that into consideration to get the correct diameter for the center (i.e., deduct half of the wire width from the radius). The wire tool might also be used, just as it was for the outer circle, but then there may be a problem getting it to fill completely.

    Other changes:
    1) Centered the pad/via. You can move it to the edge, if you want.
    2) Deleted the t-cream layer (#31 ) from the SMD pads. That will prevent a manufacturer from putting solder paste on those pads.

    Something to consider:
    1) Add a t-finish layer (#33) over the same areas as the t-stop (#29). You can then specify a special finish for the contact areas, such as gold plating.

    FYI, the problem with the polygon first time was that I used a zero line width.to make calculating of the circle diameter easier. That caused a DRC failure that I could not get around. Changed the width and it worked.

    John

    View attachment Dome-Key1.zip
     
    Last edited: Feb 21, 2013
  19. tagaide

    tagaide New Member

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    ok , this is great, the pad within the center polygon was hidden, was there a specific reason for it?
    does this pad defines a hole needs to be drilled, and also allow a connection from the bottom layer?
     
  20. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    The pad shows in my views. Do you have all layers turned on? The pad is a through-hole, plated pad. It needs a drill, which I just left at the 16mil diameter. That can be increased to be a bit easier to make. You can do that with the edit screen (use the "I" tool or right click and select properties dialog). You can also move it off center, but not too close to the edge by editing its position.

    BTW, Eagle can be command or menu driven, as you know. The manual seems to stress commands, but even Cadsoft suggests the menu edit function is often easier. For example, when laying down pads, just make them about right, then go to edit (properties) and enter the positions you want. In this specific example, I moved the pad just by setting both dimensions to zero. You can leave the first (X) as 0, and put some other number for Y to see the effect. Such moves are very helpful when the grid doesn't match what you want to do.

    When you use the circle tool, you can adjust radius with the dialog. Unfortunately, when you use the polygon tool, you cannot do that.

    John
     
  21. tagaide

    tagaide New Member

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    Hi John, it took some time to get the board all ready. Its in a pretty good shape. today i went to the metal workshop to try and load it intot the cnc machine, i think it did not like the polygon. The export to dxf format ended up in a 6 megs file and things got messed up when loading it into the cad cam software.

    For the moment, i know what to do i think. I will try and have someone check what happens when exporting to gerber.

    thanks for all the help and guidance you have given me, its much appreciated.
     

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