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Size of micro via for power

C Shiva

 Hello friends,

     What's the size of micro via which is used for power pin's? I need to put power via's in a HDI Type III board. I planed to put 10mil drill and 20mil pad OR 12mil drill and 24mil pad micro via's. Is it fabable? And for buried via's, is the above dimensions are ok? If anyone has experience with it, please help me.

 Normally we are using 5mil drill and 12mil pad micro via's for signals.

Thanks,

Shiva.

  • Robert Finley

    Are you putting uvias inside the SMT pad or do they have to be outside?

    A common practice is to add extra vias whenever possible to high-current SMT connections to beat Ohms law.

    Not so common though is to add copper between power pads, flooding them.  This can cut the overall resistance but you will be relying on your soldermask to prevent solder ball collapse in BGAs.   It also makes Xray inspection more of a challenge.

    Might ask your fabricator(s) what the largest laser via diameter they can drill.  You probably don't want them substituting a smaller size.

     

  • C Shiva

     Thanks Robert for your reply. Since the board is high end i need to put the uVia's in both inside pad and out side. In some places of board due to space constraint, i can't put more uVia's. So i'm thinking to increase the size of uVia's.

    Shiva.

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