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April 2001

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Subject:
From:
Jorge Santana <[log in to unmask]>
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Date:
Mon, 16 Apr 2001 09:00:11 -0500
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 Francis ;

 You also must be aware that lower humidity also means more potencial ESD
events, when you solve one problem you must check if the solution will not
create another one ...

 Thanks




-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Francois Monette
Sent: Friday, April 13, 2001 7:11 AM
To: [log in to unmask]
Subject: [TN] Humidity and temperature specification


Francis,

Your SMT support group is right to be concerned with popcorn if you are
assembling MSDs, however this does not mean that your environment should be
less than 30%. The proper guidelines for storage and handling of
moisture-sensitive components are clearly defined in the joint IPC/JEDEC
standard J-STD-033 : Standard for Handling, Packing, Shipping and Use of
Moisture/Reflow Sensitive Surface Mount Devices.

Take note that all MS components are qualified and classified based on worse
case conditions of 30C/60%RH. The maximum floor life that is specified on
the MS labels represents the safe limit within this range of temperature and
humidity. If your environment is significantly different this will have a
significant effect on the maximum floor life. If the RH is less than 60% the
floor life will be longer, if it is above 60% then it will be shorter. You
can actually compensate for your actual production conditions by using table
5 in J-STD-033 : Derating due to factory environmental conditions. This
de-rating varies based on the actual MS level and component body thickness
of each component.

Francois Monette
Cogiscan Inc.
50 De Gaspe, Suite A5
Bromont, Quebec, Canada, J2L 2N8
Tel : (450)534-2644
Fax: (450)534-0092
www.cogiscan.com




Date:    Thu, 12 Apr 2001 12:16:34 -0400
From:    Francis Sun <[log in to unmask]>
Subject: Re: Humidity and temperature specification

I thank everyone for their replies.
30% to 70% seems to be the general guideline.
However, the SMT support group is concern that humidity level over 30% will
cause 'popcorn effect' on the plastic package components.
I believe that it is a valid concern, but is the 30% level limit legitimate?
I would appreciate any feedback from learned colleagues.


Best Regards;
Francis Sun
Mark IV Industries

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