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Place_Bound_Top vs Dfa_Bound_Top vs Package_Keepout_Top?

EE92780

Can anyone please explain the difference between "Place_Bound_Top" "Dfa_Bound_Top" and "Package_Keepout_Top?"  When using the built in package wizard, it seems to create an identical shape for the Place and Dfa bound tops.  So why have two?  How do these differ fundamentally from the package keepout area?  Thanks!!!

  • mcatramb91
    Place_Bound_Top
    Used to ensure you don’t place components on top of each without getting a DRC.  This boundary
    normally defines the component area which may or may not include pins of surface mount devices.
    This boundary can also be assigned a component high to be verified at the board level and checked
    to the Package_Keepout_Top boundaries or any other special component clearances.  If this boundary
    does not exist than it will be automatically created based on the Assembly_Top outline and the outer
    extents of the component pins. This boundary can only be defined at the symbol level (.dra).
     
    Dfa_Bound_Top
    Used by the Real Time Design for Assembly (DFA) Analysis to check clearances between components
    driven by a Spreadsheet based matrix of components.  This boundary normally or can be different then
    the traditional Place_Bound_Top boundary and it may include pins of surface mount devices.
    If this boundary does not exist than the DFA checks default to using the Place_Bound_Top boundary.  
    This boundary can only be defined at the symbol level (.dra).

    Package_Keepout_Top
    Used to ensure you don’t violate placement keepout areas or high restricted area in a design.
    This boundary can only be defined at the board level (.brd) and cannot be added to the
    symbol level (.dra) unless it is part of a Mechanical Symbol (.bsm)

    Hope this helps,
    Michael Catrambone
    UTStarcom, Inc.
  • lcanx2
    2 questions.

    1)      Can you really not build a symbol to include a package_keepout_top or am I misreading the reply?

    2)      CADENCE states in their help that the Dynamic DFA for component clearances is not available while in the “Edit Move” command, only the “Place Manual” command.  Do other users see the advantage of having Dynamic DFA checking available to them regardless of what command is being used to move a symbol?

    >Package_Keepout_Top

    >Used to ensure you don’t violate placementkeepout areas or high restricted area in a design.  

    >This boundary can only be defined at the boardlevel (.brd) and cannot be added to the symbol level (.dra)

    >unless it is part of a Mechanical Symbol(.bsm)
  • mcatramb91

    Yes that is correct.  PACKAGE_KEEPOUT_TOP can only be defined at the board level (.brd) and it is used to prevent components from being placed in a particular area of design and in some cases a particular height.  The only exception is PACKAGE_KEEPOUT_TOP can be added to a Mechanical Symbol (.bsm).  A mechanical symbol is used to generate a master Board Outline, Keepouts and Keepin for a design which is generated the same way a package symbol (component) is generated but with a mechanical symbols you have the ability to add PACKAGE_KEEPOUT_TOP to it during creation.  Most people do not use Mechanical Symbols for their Master Board Outline symbol anymore and instead use a Master Layout (.brd) which contains the master board outline which was generated at the Layout level (.brd)

    YES I do see a benefit of having the Dynamic DFA for component clearances available during Edit Move.  I thought I heard that this functionality was coming in a future release at this past CDNLive! but I may be mistaking.

    Hope this helps,
    Michael Catrambone
    UTStarcom, Inc.

  • lcanx2
    Hi Mike,

    I have to respectfully disagree.  I have added Package Keepout Top (as well as Bottom) to non-mechanical symbols without issue.

    Bill

    Yes that is correct.  PACKAGE_KEEPOUT_TOP can only be defined at the board level (.brd) and it is used to prevent components from being placed in a particular area of design and in some cases a particular height.  The only exception is PACKAGE_KEEPOUT_TOP can be added to a Mechanical Symbol (.bsm).  A mechanical symbol is used to generate a master Board Outline, Keepouts and Keepin for a design which is generated the same way a package symbol (component) is generated but with a mechanical symbols you have the ability to add PACKAGE_KEEPOUT_TOP to it during creation.  Most people do not use Mechanical Symbols for their Master Board Outline symbol anymore and instead use a Master Layout (.brd) which contains the master board outline which was generated at the Layout level (.brd)

    YES I do see a benefit of having the Dynamic DFA for component clearances available during Edit Move.  I thought I heard that this functionality was coming in a future release at this past CDNLive! but I may be mistaking.

    Hope this helps,
    Michael Catrambone
  • mcatramb91

    Bill,

    At one point the symbol editor would not allow you to generate a package symbol with a PACKAGE_KEEPOUT_TOP shape because it was an illegal subclass for a package symbol but for some reason it is no longer doing this and allows the symbol to be created.  I don't know if it is a bug or an enhancement to the tools.

    This is sort of a loaded question which would lead to a lot of discussion but this is the place for it so here it is:

    Why would you need to add a PACKAGE_KEEPOUT_TOP to a Package Symbol when PLACE_BOUND_TOP actually does what you need?  In other words, why not expand the PLACE_BOUND_TOP to meet your clearance requirements that you are trying to meet with the addition of the PACKAGE_KEEPOUT_TOP.

    If the PACKAGE_KEEPOUT_TOP defined in the Symbol Level violates the PACKAGE_KEEPOUT_TOP at the Board Level you will never see a DRC Error which, in my opinion, you would want to see.

    Regards,
    Michael Catrambone

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