Narrowed this down to a reaction of the PCB ImAg finish and the Loctite 384.
Turning green/blue just putting the material on the pa.  No part installed,
not soldered, no activator applied.

Ashesive:
Alumina trihydrate: 60-100%
Tetrahyrofurfuryl methacrylate: 10-30%
Hydroxyalkyl methacrylate: 5-10%
Cumene Hydroperoxide: 1-5%
Saccharin: 1-5%
Ethylene Glycol: 0.1-1%

+

ImAg

= ??


Kevin Glidden
Manufacturing Engineer
Astronics Luminescent Systems Inc.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, December 01, 2006 2:41 PM
To: [log in to unmask]
Subject: Re: [TN] Any Chemical Engineers out there?

Hi Kevin - a quick FTIR analysis of the blue residue should identify its
composition and assist in your "where did this come from" effort. Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]



             Kevin Glidden
             <[log in to unmask]
             COM>                                                       To
             Sent by: TechNet          [log in to unmask]
             <[log in to unmask]>                                          cc

                                                                   Subject
             12/01/2006 01:20          [TN] Any Chemical Engineers out
             PM                        there?


             Please respond to
             [log in to unmask]
                    om






Just a shot in the dark, but any chemistry majors in here?

Here is a new problem that popped up-

We bond some heat generating components to a pcb using loctite 384.  That is
a thermally conductive adhesive.  After the bonding is cured, the parts are
hand soldered (SMT).  We use water soluble (Kester 2331-ZX flux) and 63-37
alloy solder.  The PCB finish is ImAg.  What resulted was a BRIGHT blue
liquid residue.  Bright blue like the color of blue cotton candy or blue
raspberry candy.  It appears to be water soluble (visibly removed with DI
water, not sure about ionically)

I am thinking this has to be some chemical Rx, so I mixed a little adhesive
and flux in a beaker, but no color, even with a little heat.  Could it be
from chemicals in the PCB finish?  We use this same combo of materials very
regularly and have never observed this phenomenon before.  All materials
within shelf life.

Per the MSDS for the adhesive:
Alumina trihydrate:                    60-100%
Tetrahyrofurfuryl methacrylate:    10-30%
Hydroxyalkyl methacrylate:        5-10%
Cumene Hydroperoxide:            1-5%
Saccharin:                                1-5%
Ethylene Glycol:                        0.1-1%

Per the MSDS for the adhesive activator
n-Heptane:                                30-60%
Aldehyde-amine condensate:    10-30%
Isopropyl Alcohol:                    10-30%
3-ethyl-2-propylquinoline:            1-5%

Per the MSDS for the flux:
propan-2-ol:                            50-100%
glycerol:                                    10-25%
2,2'-iminodiethanol                       2.5-10%
dimethylammonium chloride        2.5-10%
lactic acid                                    2.5-10%
hydroxyacetic acid                        <2.5%

Thanks in advance

Kevin G.

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