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January 2013

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From:
Douglas Pauls <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Mon, 21 Jan 2013 10:03:26 -0600
Content-Type:
text/plain
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Well, if the connectors do not need to be sealed, then you might consider 
silicone/vinyl boots that slip over the connectors and go down to the 
board level.  You can get them from companies like Dempsey or Shercon. 
Only takes a few seconds to slip them on and gives you 30-40 mils of wall 
thickness to keep wicking down.  They have a tendency to last for quite a 
while and are fairly cheap to replace. 

Doug Pauls



From:   Ioan Tempea <[log in to unmask]>
To:     "[log in to unmask]" <[log in to unmask]>, 
TechNet E-Mail Forum <[log in to unmask]>
Date:   01/21/2013 09:37 AM
Subject:        RE: [TN] Coating around connectors



Thanks Doug and Phil,
 
The connectors do not need environmental sealing, I just need to figure 
out how to stop coating wicking on the pins.
 
Now sealing around the connectors just to liquid coating infiltration 
proof them will definitely apply a thicker layer on the joints and I 
wonder if this could be detrimental to the long term reliability. Am I 
right?
 
Regards,
 
Ioan Tempea, ing.
Ingénieur principal de fabrication / Senior Manufacturing Engineer

 
950 RUE BERGAR, LAVAL, QC, H7L 5A1
T+ 1 (450) 967-7100, EXT244
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Lauréat Dunamis 2012
Entreprise manufacturière / Gestion du capital humain
 
De : [log in to unmask] [mailto:[log in to unmask]] 
Envoyé : January-21-13 10:00 AM
À : TechNet E-Mail Forum; Ioan Tempea
Objet : Re: [TN] Coating around connectors
 
Ioan, 
I guess it depends on what your end use environment is.  If it is a 
condensing humidity environment, or the possibility that condensed water 
will flow into the connector, then you would want the connectors 
permanently sealed off.  Phil Kinner has given some good suggestions on 
dispensing quick cure masking materials, but then you need to remove those 
materials and that leaves some openings in the coating.   

What I might suggest is using a benchtop dispensor, such as a PVA350, and 
dispense a UV cure adhesive/sealant around your connectors.  You can 
quickly cure it, then coat up to that material or on it if you prefer, and 
you seal off the connector. 

Doug Pauls 



From:        Ioan Tempea <[log in to unmask]> 
To:        <[log in to unmask]> 
Date:        01/21/2013 07:07 AM 
Subject:        [TN] Coating around connectors 
Sent by:        TechNet <[log in to unmask]> 




Dear Technos,

Got a tough one now!

We apply 1B31S with our Asymtek selective coating machine and there are 8 
difficult connectors, where coating infiltrates inside and on the pins. 
What can I do to prevent this from happening?

We've tried to manually lay down some non-diluted coating around the 
parts. Kinda stops infiltration, but it's long and manual, many bubbles in 
the coating layer. We've tried gel coating around the connectors, but it 
cracks, leaving a lot of room for infiltration. Not to mention that the 
closer the selective nozzle gets to connectors, the more prone we are to 
finding spots on the pins (it seems impossible to completely eliminate 
satellites when the nozzle head changes direction or at start-stop).

Ideally we would find something that can be dispensed around those 
connectors in a controlled manner (even if we need to buy some sort of 
table top dispensing machine) so that we seal them, followed by selective 
dispensing on the rest of the board. We really want zero or minimal manual 
work, as it's not repeatable.

Any suggestions?

Thanks,

Ioan Tempea, ing.
Ingénieur principal de fabrication / Senior Manufacturing Engineer
[signature002]<http://www.digico.cc/>

950 RUE BERGAR, LAVAL, QC, H7L 5A1<http://g.co/maps/2gh3f>
T+ 1 (450) 967-7100, EXT244
------------------------------------------------------------------------
 [signature001] <http://www.facebook.com/pages/Digico/277076778479>
------------------------------------------------------------------------
Lauréat Dunamis 2012<http://digico.cc/dunamis-2012/>
Entreprise manufacturière / Gestion du capital humain


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