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September 2010

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TechNet E-Mail Forum <[log in to unmask]>, "Carroll, Thomas A" <[log in to unmask]>
Date:
Mon, 6 Sep 2010 09:40:22 -0500
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TechNet E-Mail Forum <[log in to unmask]>, "Wenger, George M." <[log in to unmask]>
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"Wenger, George M." <[log in to unmask]>
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Anytime you heat rosin a portion will de-characterize (i.e., change it's character and become solvent insoluble because of polymerization or oxidatation).  If you use ultrasonics or forceful spray cleaning with a "good" solvent, which I believe IPA isn't, the small amount of de-characterized rosin (i.e., white residue) gets carried way with the non-decharacterized rosin.  If you use IPA without aggressive action the rosin will dissolve and rinse away and once the de-characterized white residue on the surface touches the PCB it sticks to it and is extremely difficult to remove.  Our experience is like Tom's.  In our lab we routinely use a d-limonene based terpene based cleaner (Petroferm EC-7)to remove rosin flux residue. However, even the terpene based cleaner won't always remove white residue from a PCB once it is stuck on the PCB.  When this happens the trick to remove the white residue is to apply more liquid flux to the PCB and let it sit for several minutes.  The white residue will tend to un-stick from the PCB and float on the rosin and then it can be washed off with a terpene solvent.
Suggestions:
1. Reduce your soldering temperature to minimize de-characterized flux residue.
2. Use a "good" rosin removing solvent like a terpene.
3. Use a "forceful" cleaning process that quickly washes away the rosin residue which will carry away the white residue with it.

Regards,
George
George M. Wenger
Senior Principal FMA  / Reliability Engineer
Andrew Corporation - Wireless Network Solutions
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 Office (732) 309-8964 Mobile
E-mail: [log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carroll, Thomas A
Sent: Monday, September 06, 2010 10:21 AM
To: [log in to unmask]
Subject: Re: [TN] Hand Soldering

Ken,

Assuming you are using IPA to clean your rosin residues and thus occasionally getting the white residues, for your applications I would recommend looking at your soldering temperature first.  If it is too high it could be helping to create your white residues.

The most common cause of white residue is oxidation of rosin. Rosin flux constituents oxidize due to excessive solder temperature, flux aging, or moisture when the rosin-fluxed assemblies are cleaned with organic solvents. Polymerization of small amounts of rosin from heat exposure may also play a role in the formation of white residue.

If your soldering temperature is not excessive then look into a separate cleaning chemistry for your current soldering process.  I have had good success with Terpene based cleaners for rosin.

Regards,
Tom Carroll, CQA, CIT, FAA ODA Unit Member
Supplier Quality Engineer
Boeing Defense, Space and Security - East Region Supplier Quality
Currently on Short Term International Assignment for BCA in Sweden
eFAX: 314-777-1845
Cell: 215-692-2463
Softphone Phone Number: 314-545-2358
Saab Sweden Phone: +46 (0)13 185972
Sweden Cell Phone (In Sweden): 0700 945414
Sweden Cell Phone (Outside of Sweden): +46 700 945414
email: [log in to unmask]

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-----Original Message-----
From: Kenneth Wood [mailto:[log in to unmask]] 
Sent: Monday, September 06, 2010 3:11 PM
To: 'TechNet E-Mail Forum'; Carroll, Thomas A
Subject: RE: [TN] Hand Soldering

Well, the PCB's can be any thickness really and I use multiple surface finishes but primarily HASL and ENIG.
I'm using standard Kester rosin core solder.
The main use is building prototypes on my bench so it doesn't have to meet any certain classes or requirements...just would like it to clean up better.
Ken

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carroll, Thomas A
Sent: Monday, September 06, 2010 8:51 AM
To: [log in to unmask]
Subject: Re: [TN] Hand Soldering

Ken,

Tough question without more details.  The best setup depends upon a number of factors including but not limited to the following:

PWB surface finish
PWB thickness (heat sink properties)
Component surface finish
Are you using additional liquid flux or just flux cored solder wire 
Solder alloy being added 
Ease of cleaning soldered area 
Type of cleaning used (cleaning media and hand or machine process) 
Post Soldering Ionic Cleanliness requirements 
Post Soldering Non-Ionic Cleanliness requirements

I can go on but you get the idea.

Provide more details and you should get the response you desire.

Regards,
Tom Carroll, CQA, CIT, FAA ODA Unit Member Supplier Quality Engineer Boeing Defense, Space and Security - East Region Supplier Quality Currently on Short Term International Assignment for BCA in Sweden
eFAX: 314-777-1845
Cell: 215-692-2463
Softphone Phone Number: 314-545-2358
Saab Sweden Phone: +46 (0)13 185972
Sweden Cell Phone (In Sweden): 0700 945414 Sweden Cell Phone (Outside of Sweden): +46 700 945414
email: [log in to unmask]

P Go Green! Please do not print this e-mail unless necessary.

>NOTE: This communication may contain privileged or other confidential
information. If you are not the intended recipient, or believe you have received this communication in error, please do not print, copy, retransmit, disseminate, or otherwise use the information. Also, please indicate to the sender that you have received this e-mail in error, and delete the copy you received. Thank you.
>EXPORT COMPLIANCE STATEMENT:
>"The information contained herein is or may be controlled by the
International Traffic in Arms Regulations (ITAR), 22 CFR 120-130, and may not be exported, or disclosed to a foreign person, whether in the United States or abroad, without prior U.S. Government written approval"

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Kenneth Wood
Sent: Monday, September 06, 2010 2:30 PM
To: [log in to unmask]
Subject: [TN] Hand Soldering

Hi all.
What is the best setup for hand soldering as far as solder / cleaner?
Rosin core? Water soluble? No-Clean?
What cleaner too?

I've been using rosin core with various cleaners but I have a hard time with the white residue the cleaners leave.

Thanks
Ken





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