agree with dave's 100%.  in addition, if you are operate above 100C,  
look like you might deal with high power/high current condition.  if  
it is in DC, you might have field assisted growth if your test was  
done in static  (storage  condition  more than  100 C for your test  
without bias... ).  Be careful  your prediction.  you may see IMC  
growth with rapid  voiding  formation if it is high  power  in  
specific location depend on the design  and layout - how good is your  
designer?  you don't have to answer ;-).  my 1. 4 cents.
  jk
On May 19, 2016, at 9:11 AM, David Hillman wrote:

> Hi Gil - you hit on one of my soapbox topics so I have respond!  
> What data
> source are you citing that shows 6 micrometers of IMC results in  
> solder
> joint failure? And for the IMC, is it the Cu3Sn or the Cu6SN5  
> phase? The
> industry is constantly "reminded" that thick IMC is brittle and  
> will cause
> a loss of solder joint integrity but where is the data? Everyone is in
> consensus that IMC phases have been shown to have brittle  
> properties but
> when I push for hard data/investigations/studies, demonstrating  
> failures
> due to excessive, thick IMC phase, the real root cause has always  
> turned
> out to be an out of control or excessive, abusive soldering process -
> typically a soldering process most folks would  say "ohh, I  
> wouldn't do
> that with my soldering process".  For a dwell temperature of 100C,  
> I will
> grow approximately 5 micrometers of IMC ( combine Cu3Sn and Cu6Sn5  
> phases)
> in 1660 hours using the standard IMC equations for tin over copper (my
> calculations don't match the details you listed). There are multiple
> examples of electronic products in many different product use  
> environments
> that easily exceed that time and operate at that temperature yet we  
> don't
> see reports of product integrity data. Unless you  have some  
> nontypical
> variable for your product in its use environment (basically, a  
> variation of
> Doug saying "it depends" but with less gray area), I don't believe  
> you have
> a solder joint integrity concern. Don't get me wrong, I think its  
> great
> that folks are looking at how much IMC phase is produced/found on  
> their
> solder joints but I think we overstate the topic on most occasions.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> On Thu, May 19, 2016 at 7:34 AM, Zilber Gil <[log in to unmask]>  
> wrote:
>
>> Hello Technet`s,
>>
>> As we know above 6 micrometers of intermetallic (CuSn) could cause  
>> failure
>> due to brittle structure of the intermetallic. I found in some  
>> experiment
>> that at 100 deg C after 32 days the intermetallic (CuSn from  
>> Sn-40Pb) grow
>> in about 6 micron. Is it true? What should I do if the board  
>> should see 100
>> deg C for long time and what about >=90 dig?
>>
>> Thanks,
>>
>> Dr. Gil Zilber
>> Technologiest
>> Elta Systems Ltd.
>>
>> The information contained in this communication is proprietary to  
>> Israel
>> Aerospace Industries Ltd. and/or third parties, may contain  
>> confidential or
>> privileged information, and is intended only for the use of the  
>> intended
>> addressee thereof. If you are not the intended addressee, please  
>> be aware
>> that any use, disclosure, distribution and/or copying of this  
>> communication
>> is strictly prohibited. If you receive this communication in  
>> error, please
>> notify the sender immediately and delete it from your computer.
>>
>>
>> _____________________________________________________________________ 
>> _
>> This email has been scanned by the Symantec Email Security.cloud  
>> service.
>> For more information please contact helpdesk at x2960 or  
>> [log in to unmask]
>> _____________________________________________________________________ 
>> _
>>
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud  
> service.
> For more information please contact helpdesk at x2960 or  
> [log in to unmask]
> ______________________________________________________________________


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________