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From:
"David D. Hillman" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Wed, 13 Mar 2013 11:32:26 -0500
Content-Type:
text/plain
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Hi Dick - I have a split opinion - for the SEMCO type tube container, 
since the solder paste has minimum exposure to the factory environment, I 
would be minimally concern on not utilizing over night refrigeration, 
especially if you are consuming the solder paste in a couple of days. I 
would consider jars a different story since they allow for a far greater 
exposure to the environment. The safe option is to refrigerate over night. 
One way to decide is to select a product that has good yields and run a 
test - build for 3 weeks with and without refrigeration. Look at the 
product yield/defect data after the 6 weeks and see if you can 
statistically tell a difference in the two populations. Depending on how 
you fast you consume solder paste and the factory conditions, it may not 
be necessary to refrigerate over night. The solder paste formulations used 
today are much more robust to factory environmental conditions that solder 
pastes supplied 10 years ago.

Dave



From:   "Richard D. Krug" <[log in to unmask]>
To:     "[log in to unmask]" <[log in to unmask]>, 
TechNet E-Mail Forum <[log in to unmask]>
Date:   03/13/2013 11:23 AM
Subject:        RE: [TN] Cooling of Solder Paste Overnight



Both.  I have more concerns with the proposed when it is a jar that has 
been opened, then closed with some quantity of ?room air?. 
 
Dick Krug, CSSBB, CSMTPE
Senior Process Engineer
Sparton Complex Systems
30167 Power Line Road
Brooksville, FL  34602-8299
p (352) 540-4012  (Internal Ext. 2012)
[log in to unmask]
 
From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Wednesday, March 13, 2013 12:04 PM
To: TechNet E-Mail Forum; Richard D. Krug
Subject: Re: [TN] Cooling of Solder Paste Overnight
 
Hi Dick - what is the solder paste container: a SEMCO type tube or a jar? 

Dave Hillman 
Rockwell Collins 
[log in to unmask] 



From:        "Richard D. Krug" <[log in to unmask]> 
To:        <[log in to unmask]> 
Date:        03/13/2013 07:42 AM 
Subject:        [TN] Cooling of Solder Paste Overnight 
Sent by:        TechNet <[log in to unmask]> 




It has been proposed that we take left over solder paste and store at ~60 
F overnight to extend life and integrity of paste.  This would be paste in 
its original tube or jar, not recovered from a stencil.  We are located in 
Florida.  During the summer, when the AC is reduced overnight, temperature 
in the building gets to ~85 F. 

Has anyone done this?  What are the pro's and con's? 

Dick Krug, CSSBB, CSMTPE
Senior Process Engineer
Sparton Complex Systems
30167 Power Line Road
Brooksville, FL  34602-8299
p (352) 540-4012  (Internal Ext. 2012)
[log in to unmask]

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