Hi, Steve,
What were the boards like prior to soldering - OK, I gues or you wouldn't
have processed them. I had a little problem with mask just over a year ago
with ENIG boards that had Elecktra Carapace LPI mask applied to them.
Post-soldering the mask had pretty-much disappeared from the copper, adn on
quizzing the fab house, they admitted that they'd used the wrong hardener
by mistake. One hardener is used for HASL boards, another for ENIG to
withstand the aggressive plating chemicals.
Our boards looked fine before soldering. Could you have a
conceptually-similar situation with the dry film? We used some touch-up
mask to repair the damage to our boards (fortunately only 6 prototype
units, but still V expensive).
All the best
Peter
Steve Gregory <[log in to unmask]> 29/01/2003 03:02 AM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to SteveZeva
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: [TN] Flaking Mask
Hi All!
I've got a problem that I ran into a few years back, and I thought I had
solved it.
We've built a couple of pretty pricey assemblies ($4,000 +), that has the
mask flaking off of all copper features. Via's, traces, everything...
When we had this problem before, a Dynachem Dynamask dry film was used.
Since then, whenever dry film mask is called out on the fab drawing, we
specifically call out Dupont Vacrel 8100, since we learned back then that
this dry-film is not affected by the Aquanox XJN we use in cleaning. Go to:
http://www.stevezeva.homestead.com and look at MaskFlake 1-3
The mask flakes off when it is washed in our Electrovert MCS-1000 batch
cleaner after 2 or 3 wash cycles. We use the Kyzen Aquanox XJN according to
the manufacturers specifications. We run it in a 20-25% concentration with
DI water. The concentration is measured twice a day with a refractometer.
The cleaning cycle is as follows:
6-minute wash
4-minute rinse
2-minute final rinse
6-minute dry
Wash Temperature 140 F.
Rinse Temperature 110 F.
We have two fully loaded assemblies that exhibit this problem, and at
$4,000 each, this is not good.
The fab vendor swears that the Dupont dry film was used. But over the past
few years since we've always called out the Vacrel, we have NEVER had the
problem like we did with the Dynachem Dynamask.
Have any of you ever had this problem? Is there any way (visually) to tell
the difference between the Dupont and the Dynachem?
The way this mask came off, sure is like it was the Dynachem dry film...
-Steve Gregory-
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
-----------------------------------------------------
[This e-mail is confidential and may also be privileged. If you are not the
intended recipient, please delete it and notify us immediately; you should
not copy or use it for any purpose, nor disclose its contents to any other
person. Thank you.]
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
