Okay To Mix Lead and Tin/Lead Solder?

Discussion in 'The Projects Forum' started by mossman77, May 14, 2015.

  1. mossman77

    Thread Starter New Member

    Feb 2, 2015
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    I need to solder a BGA chip back onto a PCB which was originally attached using lead-free solder. Is it okay to use tin/lead solder to reattach the chip? I removed as much of the lead-free solder from the PCB pads as possible but they are still tinned with lead-free. Is it a good idea to tin the pads with the tin/lead solder first to ensure a better bond? And should I use Pb-free reflow temperatures (220° C) since there will be residual Pb-free solder on the pads?
     
    Last edited: May 14, 2015
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I would have no problem with it, just not RoHS certified!:p
    Max.
     
  3. mossman77

    Thread Starter New Member

    Feb 2, 2015
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    Let me rephrase, will using tin/lead solder to reattach a BGA chip that was originally attached using Pb-free cause any issues (cold joints, discontinuities, etc.) and what are some tips for ensuring a successful rework?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If it is any comfort I have found that lead/tin solder is a far better bond, the RoHS versions are a pain to use, IMO they both combine very easily when reworking.
    Max.
     
  5. jpanhalt

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  6. mossman77

    Thread Starter New Member

    Feb 2, 2015
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    I don't have enough experience to know the importance of having a eutectic mixture. My main concern is that everything becomes liquidus and my solder joints are solid. Don't mean to come off as rude, but can someone answer my specific questions (tinning pads, elevated temperature)?
     
  7. mossman77

    Thread Starter New Member

    Feb 2, 2015
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    That's a very informative article. Thanks. So from what I've gathered, if I am going to use a SnPb solder, I should choose one with a lower Sn content since the Pb-free has a higher Sn content. Is this correct? If so, would something like Sn10Pb90 work better than Sn63Pb37?
     
  8. ScottWang

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    Aug 23, 2012
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    Too much inappropriate contents, so deleted the inappropriate contents and closed the thread.
     
  9. ScottWang

    Moderator

    Aug 23, 2012
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    I closed it because there are some inappropriate contents, another moderator deleted the contents, I also hope the members could calm down, now someone said that he was interested in this, although he didn't see the inappropriate contents, now I reopen it, but if any inappropriate contents happen again then I or other moderators may close it again, I hope members could keep a good mood to discuss the technical problem, if any argue only in technical, no personal, no emotional, thanks ... :)
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    The answer was given way back in post #2.
    Hope the TS read it.
     
  11. mossman77

    Thread Starter New Member

    Feb 2, 2015
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    That's the kind of answer I was looking for. Thanks Max!
     
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