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 0.4mm pitch bga and board thickness have become 280 mills 

Last post Mon, Jun 24 2013 4:11 AM by steve. 5 replies.
Started by Nayyierwajih 21 Jun 2013 12:40 AM. Topic has 5 replies and 962 views
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  • Fri, Jun 21 2013 12:40 AM

    0.4mm pitch bga and board thickness have become 280 mills Reply

    Hi all

    We have 0.4mm pitch bga and board thickness have become 280 mills ,we can not drill a 5 mills via with 8 mills pad upto this thickness,what is the solution,any suggestions?

    Regards

    Nayyier 

    • Post Points: 20
  • Fri, Jun 21 2013 3:51 AM

    • steve
    • Top 10 Contributor
    • Joined on Fri, Jul 18 2008
    • Woking, Surrey
    • Posts 1,211
    • Points 19,710
    Re: 0.4mm pitch bga and board thickness have become 280 mills Reply

    Try using a blind via from TOP-Layer2 which can the size you want and use larger "core"vias that can be drilled through the whole PCB.

    • Post Points: 20
  • Sat, Jun 22 2013 4:45 AM

    Re: 0.4mm pitch bga and board thickness have become 280 mills Reply

     Hi Steve

    Right now we have VIA on pad and drill is just 5 mills with pad of 8 mills,with this pad size we have just 2.374 mils pad to line,how we can increase the via size because it will decrease the pad to line distance which is minimum,if there is any misunderstanding then please explain your idea.

     Regards

    Nayyier

    • Post Points: 20
  • Mon, Jun 24 2013 1:20 AM

    • steve
    • Top 10 Contributor
    • Joined on Fri, Jul 18 2008
    • Woking, Surrey
    • Posts 1,211
    • Points 19,710
    Re: 0.4mm pitch bga and board thickness have become 280 mills Reply

    You need to consider using blind and buried vias to enable you to leave the via from top-l2 at the size it is. You can use buried vias and core vias to get the track out.

    • Post Points: 20
  • Mon, Jun 24 2013 3:48 AM

    Re: 0.4mm pitch bga and board thickness have become 280 mills Reply

    Hi STEVE

    Having stack vias (BLIND/BURRIED) is a good approach but that is too costly:))

    Will you please explain the core vias?

    many thanks for your reply

    Regards

    Nayyier 

    • Post Points: 20
  • Mon, Jun 24 2013 4:11 AM

    • steve
    • Top 10 Contributor
    • Joined on Fri, Jul 18 2008
    • Woking, Surrey
    • Posts 1,211
    • Points 19,710
    Re: 0.4mm pitch bga and board thickness have become 280 mills Reply

    Core vias are used in a blind/buried stack where for example you have an 8 layer board, you use blind/buried (microvias) from l1-l2 an l2-l3 then a core via crossng the core material from l3-l6 then l6-l7 and l7-l8 are microvias again. With the drill diameter you have this type of construction may well be your only option. Try talking to your fabricator who should be able to give you options / costs for this type of design. 

    • Post Points: 5
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Started by Nayyierwajih at 21 Jun 2013 12:40 AM. Topic has 5 replies.