Hi Jon,

I'm not sure what the drying time is on the AR that you are using but I know
with the UR we use takes about a week to fully dry. We experienced a
situation where we were having some boards built and coated in Mexico. The
boards were put into ESD bags after a couple of days and shipped to our
facility. A combination of not being fully dried and sitting in a hot truck
in the Mexican sun at the border cause the bags to stick to the coating.
When we tried to remove the bags they had to be cut away they were stuck so
badly.

I guess what I'm saying is to make sure that they are fully cured before
putting them into the "proper" ESD packaging.

KennyB

-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Wednesday, September 03, 2008 8:05 AM
To: [log in to unmask]
Subject: Re: [TN] ANTISTATIC MATERIAL QUESTION

Date:    Tue, 2 Sep 2008 10:43:10 -0500
From:    "Roberts, Jon" <[log in to unmask]>
Subject: ANTISTATIC MATERIAL QUESTION

We have been noticing if bubble wrap is allowed to come in direct
contact with a circuit card assembly (non ESD and ESD) sensitive that
the bubble wrap leaves impression in the AR coating.  Do know if the
resulting impression is related to uncured coating or reaction of the
bubble wrap material?  Thanks for any information, Jon



Jon,

Not to be a stickler on coating questions, but there is no such thing as
uncured AR coating. Because the coating is lacquer, it doesn't cure, it only
dries. The solvents in which the acrylic resin is dissolved leave the
coating and all that is left is the plastic.?That plastic does not
cross-link, so it?can be redissolved at will, and that's why AR is the
strippable coating that it is.?Insufficient drying?could?contibute to the
condition you describe.?In our experience?we believe that plasticizers from
the bubble wrap (notoriously oily, nasty stuff, it even seems like the
antistatic is worse) are actually redissolving the coating in areas of
contact. This would be more noticeable if the coating were not completely
dry, since it's already somewhat melted. In any case, our solution is not to
let the bubble wrap come into direct contact with any type AR coating.

Mike Moninger
Thermospray Company Inc.

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