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Special Shapes

budnoel
Hello –
When I am creating a SMT pin in PAD Designer I typically create the same shape on the “BEGIN LAYER”, “SOLDERMASK_TOP” and “PASTEMASK_TOP” layers.  According to the IPC-7351 Land Calculator sometimes it is recommended that I create multiple identical shapes on the PASTEMASK_TOP layer so that multiple small sections of solder paste are stenciled onto a bigger land area.  Right now I am adding those shapes in PCB Editor on the “PACKAGE GEOMETRY” – “PASTEMASK_TOP” class and subclass because I can’t do this in PAD Designer.  I am familiar with creating special shape symbols in Editor and then using those in PAD Designer for unique land geometries but I am unable to create multiple shapes to use this way.  The “PACKAGE GEOMETRY” – “PASTEMASK_TOP” class and subclass are not typically called out in my artwork generation files so I have to remember to go back and add them if the symbol was created this way.  Any suggestions?  Thanks in advance for any advice.
 
Bill Noel
  • mcatramb91
    Bill,

    You are doing the most used procedure on handling this because a shape symbol cannot have multiple shapes.

    At a past company,  we created a shape symbol which had four large shapes connected together by a small strip at the center so it remains a single shape and could be used inside of a padstack.  The small strip was small enough to get eliminated when the stencil was manufactured which yielded 4 independent solder paste openings.  We also confirmed with our stencil vendors that this small strip would be eliminated as part of their standard tooling process.

    Still I think it is best to stick with defining shapes on Package Geometry - Pastemask_top to avoid any issues/or questions from the stencil vendor but I wanted to give you a possible alternative that may work for you.

    Hope this helps,

    Mike Catrambone
    Plexus Engineering Solutions
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