Ramon,
Whether or not dendrites grow is really more of an issue of how clean the
assemblies are prior to conformal coating and I would not expect the time
an assembly sits between baking and coating to be signficant. The only way
it might impact is if your assembly environment has lots of pollutants and
particulates floating around. Sitting out a long time between baking and
coating could cause such materials to be deposited under the surface. For
us, the assemblies sit in closed ESD totes when not being actively worked
on and so are insulated from any such airborne contaminants. The only
effect we ever see from leaving assemblies out for long times in humid
areas is that we sometimes get reduced adhesion. Our acrylic coatings are
somewhat touchy to excessive moisture, though even this is rare.
Of course, if you are using a water based coating, you don't have to worry
at all about humidity.
Doug Pauls
"Dehoyos, Ramon"
<ramon.dehoyos@NG
C.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
03/03/2005 01:32 Re: [TN] Cleaning Window
PM
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
"Dehoyos, Ramon"
<ramon.dehoyos@NG
C.COM>
Will dendrites grow later on, if the board stays in a bag, after
it was cleaned, for a week and then gets coated? I have a conclusion about
this question. I also like to know your opinion.
Regards,
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Douglas O. Pauls
Sent: Thursday, March 03, 2005 12:24 PM
To: [log in to unmask]
Subject: Re: [TN] Cleaning Window
Ramon,
It sort of depends on the relative humidity of where you are. Iowa in
January vs. Florida in July type of thing. We use 72 hours throughout the
company and it works pretty well.
Doug Pauls
"Macko, Joe @
IEC"
<joe.macko@L-3COM To
.COM> [log in to unmask]
Sent by: TechNet cc
<[log in to unmask]>
Subject
Re: [TN] Cleaning Window
03/03/2005 09:43
AM
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
"Macko, Joe @
IEC"
<joe.macko@L-3COM
.COM>
Ramon,
We have a couple of dry boxes and normally limit floor life between bake
out
and conformal coating to 2 hours before the boards must be stored in a dry
box. This may seem a little conservative but it has worked well for us.
Our
volumes are very low so the dry box storage concept works well.
joe
-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Thursday, March 03, 2005 7:12 AM
To: [log in to unmask]
Subject: [TN] Cleaning Window
Question to the forum:
What is the time window between cleaning/bake dry
and Conformal Coating? I hear from 32 hours to indefinite. What is your
experience?
Best Regards,
Ramon
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