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September 2018

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Subject:
From:
"lduso - Diamond-MT.com" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, lduso - Diamond-MT.com
Date:
Fri, 14 Sep 2018 10:31:27 -0400
Content-Type:
text/plain
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text/plain (108 lines)
I agree. Even stripping a board completely there will always be some
coating left between fine-pitch leads or under components. Normally, it is
only stripped for repair. Then recoated with 1A33 again.

Then again, I have customers tell me to apply 1B31 over parylene.

Lloyd Duso
Plant Manager
Diamond-MT
(814) 535-3505
www.Diamond-mt.com


On Fri, Sep 14, 2018 at 10:24 AM Douglas Pauls <
[log in to unmask]> wrote:

> I don't know Chris, I would consider scrapping the assembly. 1A33 is a
> pretty durable urethane.  You can spot strip it OK, but stripping ALL the
> coating off of an assembly is going to be pretty tough.  As Les said, the
> residues from the stripper can be harmful if not completely removed.
>
> Doug Pauls
> Principal Materials and Process Engineer
> Rockwell Collins
>
>
> On Fri, Sep 14, 2018 at 9:19 AM Chris Thierolf <[log in to unmask]>
> wrote:
>
> > Humiseal 1A33 UR was applied instead of SR. Vendor suggested removing
> then
> > re-applying SR conformal coating. If residue is a potential issue as you
> > say then the Silicone will trap the residue on the PCB. This is a
> problem.
> > I will have to do 100% electrical testing to hopefully rule out this
> > condition.
> >
> > -----Original Message-----
> > From: TechNet <[log in to unmask]> On Behalf Of Bogert, Gerald L
> (Contractor)
> > Sent: Friday, September 14, 2018 9:27 AM
> > To: [log in to unmask]
> > Subject: [EXT] Re: [TN] Humiseal Stripper 1063
> >
> > September 14, 2018
> >
> >
> > This chemical stripper gel product should only be used as a last resort
> > for removing Type UR coating when other methods of removal such as grit
> > blast or use of heat are not viable.  If the gel is not completely
> removed
> > or neutralized by cleaning process, it will leave conductive residues
> that
> > can cause improper circuit card operation.
> >
> >
> > ________________________________
> > From: TechNet <[log in to unmask]> on behalf of lduso - Diamond-MT.com <
> > [log in to unmask]>
> > Sent: Thursday, September 13, 2018 9:05 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] Humiseal Stripper 1063
> >
> > Yes and yes. I have used this many times to remove urethane coating from
> > customers CCAs. It does work but can be dangerous. Success often depends
> on
> > the coating, the thickness, and how much of the board is uncoated. We try
> > to use the most mild stripper that will get the job done sufficiently.
> >
> > Is complete removal necessary?
> >
> > On Thu, Sep 13, 2018, 19:57 Chris Thierolf <[log in to unmask]>
> wrote:
> >
> > > Anyone use this on fully assembled PCBs to remove Urethane conformal
> > > coating? Any risk to components?
> > >
> > >
> > > Chris Thierolf
> > > Principal Engineer, EE
> > >
> > > L3 Power Distribution - SPD Electrical Systems
> > > 13500 Roosevelt Blvd.
> > > Philadelphia, PA 19116
> > > Ph. 215-698-6390
> > > [log in to unmask]<mailto:[log in to unmask]> /
> > > www.L3T.com<<http://www.L3T.com<> http://www.l3t.com/>
> > > [cid:[log in to unmask]]
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