I have seen something similar before with Sn/Ag solders and also high leads,
both in die attach applications with longish reflow cycles.
Whether that's relevant or coincidence couldn't say. Thought it could beat
the time.
The Sn one may be the same as here. Then the analysis reported only Sn, but
the reporter may have dismissed any O (and C and H etc) as background from
laminate. I'm not sure the cause was ever identified but am sure it was a
long time ago. I will have to go back through some archived stuff and hope I
can find something.
--
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Vladimir Igoshev
Sent: Thursday, December 10, 2015 12:53 AM
To: [log in to unmask]
Subject: Re: [TN] What else it can be
It varies
---- On Wed, 09 Dec 2015 16:44:26 -0800 Yuan-chia Joyce Koo wrote ----
>where is the origin of the pwa? (country of origin).
>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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