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Pin numbering

LSAUGE

Hello,

Sorry, I have the impression that I ask a lot of questions these days. ^^'

I have two questions concerning pin numbering :

1) In a package symbol, I have two mechanical holes. These mechanical holes have a pin number. Is it mandatory to have a pin number for mechanical holes ? It's just a hole for guiding the plastic part of the component and I don't want to have a pin for these holes in the schematic in Capture.

2) Is it mandatory to have the same number of pins on the schemtic than on the footprint ? The reason is that I have a schematic that have a lot of relays. For readability purposes, I draw the relay symbol as a simple switch with two pins but in fact the footprint has 4 pins (2 pins for the coil of course). Do I have to have 4 pins in my schematic or is there a workaround ?

Thanks a lot in advance

Loïc

  • Wild

    1. Mechanical pins do not need to be numbered, but must be defined as mechanical in the footprint.

    2. I use a lot of form 2C relays- I define them heterogeneously, and use a field called PARTGROUP in the schematic to allow for unique annotation.  This allows for the coil to be on a different page.

    Please let me know if you need more info.

    Wild.

  • jc teyssier
    in reply to Wild

    1. It is not mandatory to assign pin numbers to Mechanical pins in components BUT theses pins will bring drc in case in higth volage groups on brd. We assign pin numbers to ALL pins in our components so we can use spacing groups also on theses pins. Not doing so will bring to use a default value and it is not acceptable in our case (some board have hogth spacing values and we have to know what's really going on, even between layers) The tip is that schematic have to have also pin numbers for theses pins: engeeners add spacing constraint on it at schematic level

    2. Same as Wild answer

  • Wild
    in reply to jc teyssier

    Item 1 - Please correct me if I am wrong this, but is there not a constraint in spacing for holes?  Please note I am still in Rev 16.6

  • jc teyssier
    in reply to Wild

    Yes a constraint exist but it is fix and apply to all mechanical pad.

    Say a connecor with a group of net to be 5mm away from an other group.. One hole is fully located into group1, other hole between group1 and group2 and a third one fully located in group 2.

    Nets from group 1 canbe from standard spacing from first hile but 5mm from third one; same for group2 (standard spacing rom third hole and 5mm from first hole.

    If you can not assign spcing gourp on mechanical holes you can not check all. If you set 5mm for mechanical holes, all will generate drc. For verry small/simple brd should be handle (but dangereous: human can fail); for larger pcb and several groups it brings to scratch you head and regret not to have assign pin numbers to mechanical holes.

    I regulary have spacing tble with 100 or more groups: no way to handle by hand (waive: good luck if no one is false in product's life) and by a common value: the constraint will be too big in several places

  • Wild
    in reply to jc teyssier

    Can this not be applied individually to Different PCS (Physical Constraint Sets)?  We normally create PCS based on Voltage ratings.  Example Level 1 = EN90650 first level of spacing, then Level2 etc.  Also is it possible to assign a clearance property to a single (or multiple) Mechanical pin? 

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