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Date: | Wed, 27 Jul 2011 19:07:20 -0700 |
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Hello
Do you know if there are inner layer pads helping secure the structural integrity of the pth? If not I could see how overheating during soldering could easily cause the barrel to pull out of the hole.
Thomas
On Jul 27, 2011, at 5:42 PM, "Tom Burek" <[log in to unmask]> wrote:
> Hello,
> I have a PCA that hand solders 6 connector pins to an 4 layer PCB
> assembly.
> The finish on the PCB is Lead Free HASL (SN100CL) and the solder used to
> hand solder the pins is SAC305. The hand soldering is performed as a
> secondary assembly operation after reflow.
> What happens to some of the assemblies, but not all of them, is that the
> solder will wick straight up the pin, thereby not allowing a Solder joint.
> The pin can be pulled right out of the hole, revealing a PTH with no
> inner barrel.
> Completely wiped out as if it was never there in the first place. This
> phenomenon is not present on every PCB or every pin of the same connector.
> The PCB's are part of a multi-board panel.
>
> As far as I know the PCB started out with a barrel, but I cannot rely on
> this being the case as I do not believe the technician checks 100% of the
> PTH's prior to inserting the pin.
>
> Am I looking at excessive heat causing complete Copper Dissolution of the
> PTH barrel?
> or
> A PCB that may not have a barrel in every hole, part of the PCB
> fabrication process?
> or
> Any other suggestion as to which direction to head would be appreciated.
>
> Thanks in advance.
>
>
> Tom Burek, CID+
>
>
>
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