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March 2005

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Subject:
From:
"Dehoyos, Ramon" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dehoyos, Ramon
Date:
Thu, 10 Mar 2005 08:58:21 -0500
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                Hi Steve:
                                Will you describe step by step the process that these boards go through. Are these type of boards the  only affected? Or did the process all of a sudden produced this results? Does the contamination come off by scrubbing it with an alcohol soaked Q tip?
                Regards,
                Ramon
	

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Jason Gregory
Sent: Wednesday, March 09, 2005 6:37 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning residues off of PCB


Photo posted. Thanks Steve!

You can see (barely - sorry bad photo) some halo-ing around the leads. Like
I said, no other detection in open areas or two leaded devices just finer
pitch, multi-leaded devices.

Follow the link
http://www.stevezeva.homestead.com/files/residue_closeup.jpg



Jason Gregory
Manufacturing Engineer
Innova Electronics
(281)653-5593
(281)653-5594 fax
(281)212-0844 cell
[log in to unmask]


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David D. Hillman
Sent: Wednesday, March 09, 2005 4:05 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning residues off of PCB


Hi Jason! Can you send a photo to Steve for posting? A visual would help.

Dave Hillman
Rockwell Collins
[log in to unmask]



             Jason Gregory
             <jgregory@innovae
             lec.com>                                                   To
             Sent by: TechNet          [log in to unmask]
             <[log in to unmask]>                                          cc

                                                                   Subject
             03/09/2005 02:55          [TN] Cleaning residues off of PCB
             PM


             Please respond to
              TechNet E-Mail
                   Forum
             <[log in to unmask]>
             ; Please respond
                    to
               Jason Gregory
             <jgregory@innovae
                 lec.com>






Hello all,

We have some boards that I am requiring some advice on cleaning residues.

The PCBs were soldered with SN96 (Sn96.5/Ag3.5). The first pass of the
boards look great. However, the second pass looked very suspicious. We are
seeing residue that looks like dried, puddled flux residue around most of
the leads. The areas mostly affected are multi-leaded components and there
is no evidence of this residue in open (non-populated) areas of the board.
If we take something like a probe or tweezers and move them along the areas
of concern, then it flakes off, but not real easily. I am afraid to do this
in fear of damaging the laminate (these are expensive boards). We have
tried
re-fluxing them with aggressive RMA flux and re-reflowing them, but to no
avail. I have just tried soaking them, for 15 minutes,  in a 50/50 solution
of distilled white vinegar and DI water, but again, to no avail.

Does anyone have any suggestions as to something else to use that's
aggressive, but not damaging to polyimide (or the solder joints)?

TIA,

Jason Gregory
Manufacturing Engineer
Innova Electronics
(281)653-5593
(281)653-5594 fax
(281)212-0844 cell
[log in to unmask]

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