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How are you creating your testpoints?

John T

In theory we should have a testpoint for every net. How are you achieving this or coming close? There are multiple different testpoint approaches.

Let us know if you are designing by any of the following:

  1. Testpoints created in the schematic; become single pin surface components on the PCB.
  2. Assigning testpoints manually to specific component pins.
  3. Vias as testpoints with open soldermask.
  4. Other…?

Let us know if you have any problems or advice about how to approach this important part of design using the Allegro/OrCad PCB Editors. We can help the community with any questions on this.

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  • JCTEYSSIER0

    It depend on testpoint usage destination.Of course, all are free of soldermask Slight smile

    Testpoint for debug/measurement:

    - Added in schematic as components so it will have a refdes and appear on assembly drawing and silkscreen if available

    - Will be either a smd pad or thru pad. Were thru pad in old time; now pretty all are smd pad

    - Placed on the accessible layer. Generaly TOP

    Testpoint for bend of nails or flying probe:

    - Not in schematic

    - will use either thru pin, thru via or undrilled via. Testpoints placed on schematic for debugging purpose may aslo be used 

    - Ideally only on one face; can be both side on some case

    - big enougth for nails

    - distance between nails controled

    - distance to components body controled

    - 

    - One by net by default

    - Unconnected/unused pind have also testpoint by default

    - May have several one on some case (verry smal component value, small tolerance value, higth current, ...)

    - Personnaly i add these tespoint while routing, not at the end. May lead to heavy rework/modifications and/or impossiblity at the end of project. May have to revalidate routing on some case if added after routing completion. Testability IS a part of routing.

Reply
  • JCTEYSSIER0

    It depend on testpoint usage destination.Of course, all are free of soldermask Slight smile

    Testpoint for debug/measurement:

    - Added in schematic as components so it will have a refdes and appear on assembly drawing and silkscreen if available

    - Will be either a smd pad or thru pad. Were thru pad in old time; now pretty all are smd pad

    - Placed on the accessible layer. Generaly TOP

    Testpoint for bend of nails or flying probe:

    - Not in schematic

    - will use either thru pin, thru via or undrilled via. Testpoints placed on schematic for debugging purpose may aslo be used 

    - Ideally only on one face; can be both side on some case

    - big enougth for nails

    - distance between nails controled

    - distance to components body controled

    - 

    - One by net by default

    - Unconnected/unused pind have also testpoint by default

    - May have several one on some case (verry smal component value, small tolerance value, higth current, ...)

    - Personnaly i add these tespoint while routing, not at the end. May lead to heavy rework/modifications and/or impossiblity at the end of project. May have to revalidate routing on some case if added after routing completion. Testability IS a part of routing.

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