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maggic via

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Hi guys,

There is a old question. The answer might be quite simple, but it has confused me a long time.
Please give show me the light of hope.

The assumption is: there is a board, whose layer 3 is a negative plane(net GND),and there is a via(Net gnd).Now I need that via connect two pins placed at Top and Bottom,but it cannot be connected with the GND layer3.

Methord1
If i defined a circle that is bigger than the drilled hole as the thermal-relief of a pad,(Abti-pad is also defined),then in the step of Artwork Generation,The warning would likely be" no Thermal-relief,regular pad instead",but the occurrence of the pad mey be different from other normal pad(flash as thermal-relief and anti-pad),as shown in CAM software.The size of the pad would be the regular pad,obviously bigger than the hole. Now my question is:Would The via connect with the layer3?If the warning pad(regular pad) was plot away,then the result is NO;Otherwise, The answer must be Yes,right?

Methord2
if i define a Flash whose Outer-diameter is even smaller than the Hole,then in the step of artwork generation,there would propablily no warnings companied with.then when the flash was plot away,the pad would full-connect with the layer3.Is the conclusion rihgt?

Thanks a million

Kobe NCUT


Originally posted in cdnusers.org by tfsummer
  • archive

    My personal preference is not to use your Method 1 and 2 above.. They may work but you would need to output artwork to really prove that the gerber is what you expect.

    Is you intent not to connect this via to any GND planes at all. In other words, is there other GND planes in your stackup other than layer 3 ?

    Here is my two cents:

    If you do not want this via to connect to any planes at all then all you will need to do is add a property to the via called NO_SHAPE_CONNECT which will prevent it from connecting to the plane.

    If you have multiple GND planes and you do not want it to connect to layer 3 GND Plane only then I would simply add a manually void in the plane and just to be safe I would add a round route keepout over the via just in case you delete and regenerate the plane. You can add a property to to Route Keepout called VIAS_ALLOWED to prevent Via to Keepout DRCs.

    Hope this helps,
    Mike Catrambone
    UTStarcom, Inc.


    Originally posted in cdnusers.org by mcatramb91
  • archive

    Thanks Mike

    I saw your replies in my topic and the one named"uconnected via" sponcered by willbi, meanwhile, you gave me one hand twice. thank you soooo much!

    I believe I have got the pretty nice methord to disconnect a via with any one internal plan layer. Thanks

    But we may have left the "Full connect" alone, it has not been concertrated ever since willbi sponcered the "unconnected via", now I think "Full connected iva" needs focused!

    Thanks once more Mike

    Regards
    Kobe


    Originally posted in cdnusers.org by tfsummer
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