Which, of course, was just a cover story.
I should have read the preceding message closer. If the problem is in the
bake out oven, I don't know that I would use the same methods as for a
humidity chamber. In a humidity chamber, you are usually looking at
accumulated scale and mineral deposits, potentially addressing rust issues
in stainless steel (fuming red nitric acid, nasty nasty process).
If you are talking about cleaning out a standard forced air oven, you may
be better ahead buying a new oven, depending on how old and abused the old
oven is. Such ovens are usually highly abused and preventative
maintenance almost never involves cleaning out accumulated crud. You
often have baked on materials that are very hard to get off.
What I have done on occasion is to take apart most of the oven and fit a
random orbital sander with Scotchbrite pads and go over most of the
surface. Follow that with a wipe down of the chamber interior with
naphtha and then acetone, then a final wipe down with isopropanol. If you
don't wear a vapor respirator when you do this then you will justly appear
in next years Darwin Awards e-mail. This should get most of the
accumulated material off the walls. You should also take the opportunity
to replace the heating elements as they may also be coated. A final wipe
down with deionized or distilled water is also a good idea. Generally to
wash off the accumulated blood smears from all the sharp edges you come up
against.
Is it a lot of work? Yup. Is it a pain in the butt to do? Yup. Will
your maintenance people gripe and moan? Yup. Is it worth it to stop
scrapping boards? Yup.
Doug Pauls
"Whittaker, Dewey (EHCOE)" <[log in to unmask]>
12/04/2007 08:19 AM
To
"TechNet E-Mail Forum" <[log in to unmask]>, <[log in to unmask]>
cc
Subject
RE: [TN] SILVER IMMERSION BOARDS ISSUE
Doug's attempts at getting a cleaning contract for SMT reflow ovens were
foiled.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas O. Pauls
Sent: Tuesday, December 04, 2007 7:06 AM
To: [log in to unmask]
Subject: Re: [TN] SILVER IMMERSION BOARDS ISSUE
Guy,
I have been involved with the SIR Handbook for quite some time and can't
recall any sections on cleaning SMT reflow ovens. Humidity chambers,
yes.
Reflow ovens, no.
Doug Pauls
Guy Ramsey <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
12/04/2007 07:57 AM
Please respond to
[log in to unmask]
To
[log in to unmask]
cc
Subject
Re: [TN] SILVER IMMERSION BOARDS ISSUE
Yes, I think our problem was oven contamination. We started wrapping
immersion silver boards in aluminum foil (loosely) during the bake. We
have
not had any problems with delaminating or solder performance using this
bake
out process.
We have not tried to clean the oven yet, as we rarely see immersion
silver.
I understand it is rather difficult. I think there are instructions in
the
IPC SIR Handbook.
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|