Hi Dave,
I'm sure its some sort of tin oxide and it's there because of the flux. What bothers me is that the amount of it and pretty much absence of C. The peak on the EDS is miniscules. Another thing, is it conductive?
Vladimir
---- On Thu, 10 Dec 2015 05:44:49 -0800 David Hillman wrote ----
>Hi Vlad - I agree with Joyce, the SEM signature looks like tin oxide
>suspended in an organic (note the C peak). I sometimes see this as SnOx in
>the flux residue after soldering.
>
>Dave
>
>On Wed, Dec 9, 2015 at 6:55 PM, Vladimir Igoshev <[log in to unmask]
>> wrote:
>
>> No underfill or any other fancy stuff
>>
>> ---- On Wed, 09 Dec 2015 16:53:28 -0800 Yuan-chia Joyce Koo<
>> [log in to unmask]> wrote ----
>> > tin oxalyate used for epoxy catalyst... there were works for flux/
>> > underfill one step stuff utilize flux by product as catalyst for
>> > curing... (can't remember which group did that...)
>> > jk
>> > On Dec 9, 2015, at 7:03 PM, Vladimir Igoshev wrote:
>> >
>> > > Hi Dave,
>> > >
>> > > Not really. It doesn't "burn" or "curl" much under the beam, so
>> > > it's solid.
>> > >
>> > > Vladimir
>> > >
>> > > ---- On Wed, 09 Dec 2015 15:51:29 -0800 David
>> > > Hillman<[log in to unmask]> wrote ----
>> > >> Thank you Steve!
>> > >>
>> > >> Vlad - does the substance slightly charge in the SEM?
>> > >>
>> > >> Dave
>> > >>
>> > >> On Wed, Dec 9, 2015 at 5:46 PM, Steve Gregory <[log in to unmask]>
>> > >> wrote:
>> > >>
>> > >>> Hi Dave and Vlad,
>> > >>>
>> > >>> I have it up here:
>> > >>>
>> > >>> http://stevezeva.homestead.com/What_else_it_can_be.pdf
>> > >>>
>> > >>> Steve
>> > >>>
>> > >>> On Wed, Dec 9, 2015 at 4:34 PM, David Hillman <
>> > >>> [log in to unmask]> wrote:
>> > >>>
>> > >>>> HI Vlad - we can't open Dropbox here due to firewall
>> > >>>> restrictions so can
>> > >>>> you have Steve G. post the pictures?
>> > >>>>
>> > >>>> Dave Hillman
>> > >>>> Rockwell Collins
>> > >>>> [log in to unmask]
>> > >>>>
>> > >>>> On Wed, Dec 9, 2015 at 4:59 PM, Vladimir Igoshev <
>> > >>>> [log in to unmask]
>> > >>>>> wrote:
>> > >>>>
>> > >>>>> HI everyone,
>> > >>>>>
>> > >>>>> I'm attaching a link to a file showing something I'd appreciate
>> > >>>>> your
>> > >>>>> thoughts on. It's a cross-section of a QFN on an IAg board;
>> > >>>>> Pb-free/no-clean process. As you can see from the EDS spectrum,
>> > >>>>> that
>> > >>>>> greyish stuff between pins has pretty much only Sn and O in its
>> > >>>> elemental
>> > >>>>> composition.
>> > >>>>>
>> > >>>>> I know there is burn flux residue around solder joints but that
>> > >>>>> stuff
>> > >>>>> doesn't have any C in it. The question I have is what is it.
>> > >>>>>
>> > >>>>> I spoke to Bev and both of us are still puzzled.
>> > >>>>>
>> > >>>>> Here is the link:
>> > >>>>>
>> > >>>> https://www.dropbox.com/s/3wbj62vqjyhvj2y/What%20else%20it%20can%
>> > >>>> 20be.pdf?dl=0
>> > >>>>>
>> > >>>>> Thank you very much in advance.
>> > >>>>>
>> > >>>>> Regards,
>> > >>>>>
>> > >>>>> Vladimir
>> > >>>>>
>> > >>>>> SENTEC
>> > >>>>>
>> > >>>>>
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