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August 2013

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Subject:
From:
Guy Ramsey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guy Ramsey <[log in to unmask]>
Date:
Tue, 6 Aug 2013 10:27:01 -0400
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Hi Richard. 
I worried about this too and in the past tried to get a definitive answer.
This is about as close as I got.  
Q1. Is kapton tape an industry accepted way of protecting gold pads from
solder splashes?
A1. No. It is more accepted to resolve the reason behind the solder splats,
so that the added labor and cost of taping is eliminated. 

Q2. What are the chances of the kapton tape adhesive leaving behind silicone
residues on the COB pads?
A2. Depends. Kapton tape is not the same as kapton tape. Some tapes leave no
residues, but they cost more than those that do leave residues. Guess which
one buyers choose, when left with a choice?

Q3. If silicone residues are left behind, how to get rid of it?
A3. Dow claims that the OS series of solvents (VOC-free) will remove
silicone oils. Contact the manufacturer's applications engineering folks so
you're sure the chemistry you try is compatible with the oil. Are you sure
the residue is silicone?

Q4. What are the other options of covering the COB pads aside from kapton
tape?
A4. See A1.

Answers by Dave Fish, copied from SMTnet Archives. 

That said, we have been using Shercon low bond tape to protect pads for
years without measureable increase in solder defects. 
We don't coat the boards, so I don't know about coating problems. 

Guy


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Tuesday, August 06, 2013 9:18 AM
To: [log in to unmask]
Subject: [TN] Silicone adhesives on tapes

Do you think the silicone adhesive on Kapton and Shercon tapes can create a
manufacturing issue during conformal coating or for sensitive electronics?
Doug, I would be especially interested in your respected input on this
question.

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