Inge,
I think char (charring, charred) describes color or maybe color change, a 1µW
(small, but still exotherm) may not "char" the epoxy but can initiate a
localized devitrification process.
Bhanu
On 9/20/2013 6:45 PM, Inge Hernefjord wrote:
> Laura,
> It's with shivering fingers and shaking knees I dare say against such an
> authority like you.
> Let me just make a very simplified calculation. Given in that branch: max
> voltage = 1 V / series resistance ( thus also current limitation) = 1 MOhm.
> Max Pd = U2/R = 1/10exp6 = 1 uW. Not enough to char epoxy. Sorry for
> being obstinate. If I am wrong and be corrected by you, it is a honor.
> I enjoy hearing from you. One of the very first American reports I read as
> newbe in soldering was written by you.
>
> Inge
>
>
> On 20 September 2013 14:34, Laura J Turbini <[log in to unmask]> wrote:
>
>> Inge,
>> I disagree. CAF is a conductive filament which grows from the anode to the
>> cathode. It's growth rate is related to the voltage gradient, so in a low
>> voltage circuit you may never create CAF. When you do create CAF and it
>> bridges the anode and the cathode, electrons flow rapidly heating up the
>> laminate causing it to char.
>> Laura
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
>> Sent: September-20-13 1:57 PM
>> To: [log in to unmask]
>> Subject: Re: [TN] CAF, between a signal pint and ground
>>
>> Because you got two 'YES' I say 'NO'. (I can see many rise eyebrows. What
>> will happen now? The question was 'can there be exothermic damage?'. My
>> njet
>> is based on a special condition, which you may have or not have, namely the
>> impedance of the pathway. Some circuits can have 1. Extremely low voltage
>> 2. Very high resistivity. Such a combination will not produce enough energy
>> to start a exothermic issue. Just a footnote.
>>
>> Inge
>>
>>
>> ______________________________________________________________________
>> 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]
> ______________________________________________________________________
--
Bhanu Sood
Center for Advanced Life Cycle Engineering (CALCE)
Test Services and Failure Analysis Laboratory
Room 0128, Glenn L. Martin Hall (Building 088)
University of Maryland
College Park, MD 20742
Tel: +1 (301) 405 3498
Fax: +1 (301) 314 9269
e-mail: [log in to unmask]
Skype: calce_umd
website: www.calce.umd.edu/TSFA
Confidentiality Notice: The information contained in this e-mail
and any attachments may be legally privileged and confidential.
If you are not an intended recipient, you are hereby notified that
any dissemination, distribution or copying of this e-mail is strictly
prohibited. If you have received this e-mail in error, please notify
the sender and permanently delete the e-mail and any attachments
immediately. You should not retain, copy or use this e-mail or
any attachment for any purpose, nor disclose all or any part of the
contents to any other person.
______________________________________________________________________
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]
______________________________________________________________________
|
