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Subject:
From:
Jason Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Jason Gregory <[log in to unmask]>
Date:
Thu, 10 Mar 2005 08:40:28 -0600
Content-Type:
text/plain
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text/plain (261 lines)
SN96.5/Ag3.5  RA flux

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 Joyce Koo
Sent: Thursday, March 10, 2005 8:17 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning residues off of PCB [faked-from][mx]


Jason, could you tell us the flux/paste you were using?
thanks.
                  jk

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Douglas O. Pauls
Sent: Thursday, March 10, 2005 8:15 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning residues off of PCB [faked-from][mx]


Jason,
The photo makes it pretty clear that you have some residual rosin from the
flux that survives exposure to both cleaning chemicals you use.  You might
also consider using Kyzen A4520 (10% solution) or Envirosense 816 (7%
solution), both at 140F, maybe a 5 minute presoak followed by aqueous
cleaning.

I would suggest that you do not really need to clean at all, at least more
than what you are doing now.  The white residues you see are primarily
cosmetic in nature.  In the vast majority of cases that I have examined,
white residues of this low level are not a reliability hazard, purely
cosmetic.  The only time I have seen the white residues as a problem was
when they were waaaaaaaay thicker than what you have.  Vapor degreasing and
other cleaning would have removed the bad actors from the flux.

Doug Pauls

PS:  the next time you get the urge to soak electronics in an acid, tell
yourself " I don't wanna do this".



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

                                                                   Subject
             03/09/2005 03:50          Re: [TN] Cleaning residues off of
             PM                        PCB [faked-from][mx]


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






These PCBs were ran through same machines, same process, same alloy, same
convection reflow profile, just different results between the first and
second passes.

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


-----Original Message-----
From: McMullen, Kerry [mailto:[log in to unmask]]
Sent: Wednesday, March 09, 2005 3:46 PM
To: 'TechNet E-Mail Forum'; 'Jason Gregory'
Subject: RE: [TN] Cleaning residues off of PCB [faked-from][mx]


I know this is after the fact,  but are the boards being pasted by the same
printer?   If yes, then I don't know.  If not, insure they are using the
same solder paste.  I've seen NC being mixed with Aqueous before. (and
hopefully never again!)
-----Original Message-----
From: Jason Gregory [mailto:[log in to unmask]]
Sent: Wednesday, March 09, 2005 4:37 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning residues off of PCB [faked-from][mx]


Sorry,

Cleaning process is vapor degreaser, then terpene.

The residues are not white.

As far as differences between first pass and second, there were none. Both
passes are cleaned in exact manner.

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


-----Original Message-----
From: Blomberg, Rainer (FL51) [mailto:[log in to unmask]]
Sent: Wednesday, March 09, 2005 3:16 PM
To: TechNet E-Mail Forum; Jason Gregory
Subject: RE: [TN] Cleaning residues off of PCB


Try Axarel 2200 from Petroferm
(http://www.petroferm.com/PTF-053/clean/clean_frm.html).  This is what we
use for tough flux removal cases after hand-soldering.  You didn't mention
what your cleaning solvent/process was.  Are these residues white?  If the
first pass looked good, what was added afterward?  Could these be
evaporative residues from your cleaning solvent?

> Rainer G. Blomberg
> Honeywell -Space Systems Clearwater
> Staff Production Engineer
(727) 539-5534


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jason Gregory
Sent: Wednesday, March 09, 2005 3:56 PM
To: [log in to unmask]
Subject: [TN] Cleaning residues off of PCB

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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