Hi Dale,

We've seen them sit for three or four years without an issue.  It's usually
obsolete technology before we even get that far in most cases.  I can't
quote a spec for it because I have never had a need to find one, but the
absence of one may be intuitive in and of itself.  (I am sure if there is a
spec-TN will produce it shortly.)

None of our customers--who keep stock--have reported any issues to us
either.

Not much help, I'm sure.

Good luck,

Steve M.
Quality Assurance Manager

----- Original Message -----
From: "Dale Ritzen" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, February 11, 2003 14:51
Subject: [TN] Moisture in Raw Boards


> I, and our board suppliers, have looked through IPC-6011, 6012, 600, 610
and
> most of the other pertinent standards and cannot find an answer to this
> question:
>
> How long should multi-layer printed circuit boards be left out in a
> controlled ambient environment (standard factory temp/humidity) before
> pre-baking the boards becomes necessary to dry out any accumulated
moisture
> in them? We would like to minimize potential board delamination due to
> trapped moisture in the FR4 or polyamide layers (which can expand rapidly
> when the board is placed through a reflow oven or solder wave).
>
> Does anyone want to wade in on this one? We have identified a standard for
> pre-baking IC components before use in this type of high-heat environment,
> but cannot find any standard or specification pertaining directly to PCBs
> themselves. I suspect it will have to take into account the material used,
> number of layers, the definition of "standard factory temp/humidity" and
> other things related to the board and the environment it is stored in
prior
> to use.
>
> Any help in this regard would be appreciated.
>
> Thanks!
> Dale Ritzen
> Quality Manager
> Austin Manufacturing Services
> 9715A Burnet Road,  Suite 500
> Austin, TX  78758
>
> ---------------------------------------------------
> 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
> -----------------------------------------------------

---------------------------------------------------
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
-----------------------------------------------------