It Depends C 


Unprotected Cu substrates are used but I never saw bare Cu PCB. 
FWIW my opinion

Q: What is their shelf life? 
A: Very short, days to weeks  not weeks to months. It will depend on
packaging, storage life, final processing conditions in PCB manufacture
whether additive or subtractive, type of flux /soldering process you have.
Very active fluxes will permit longer shelf life than weak. Weak would be
any electronic no clean.

Q: Are they suited for double side SMT reflow? I mean, during the first
reflow the oxidizing is accelerated...
A: I would say not. second side can be a problem for OSP boards, which tend
to only come bare on first side reflow, not start bare. Nitrogen reflow
would mean second side would only be slightly worse than first.

Q: What storing/handling procedures you use?
A: Speculate nitrogen storage, possibly the inhibited packaging used for
IAg?, sealed metallised packs might be a good idea.

Q: Does the copper require any particular specifications, in order to
perform better in soldering?
A: 

Overall: The bare copper will be in a variable state on presentation to
soldering, be very vulnerable to handling contamination on line, Conclusion:
bare Cu PCB are not suited to a high yield industrial SMT process. Overall
the increase in costs would almost certainly out weigh any savings

Why do you ask?

Regards 

Mike

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Wednesday, March 19, 2008 12:42 PM
To: [log in to unmask]
Subject: [TN] Shelf lif of bare copper boards

Dear Technos,

 

Anybody using PCbs with bare copper pads and traces, no plating, no OSP, not
even solder mask? Because I have a few questions:

 

What is their shelf life?

Are they suited for double side SMT reflow? I mean, during the first reflow
the oxidizing is accelerated...

What storing/handling procedures you use?

Does the copper require any particular specifications, in order to perform
better in soldering?

Anything else?

 

Thank you,

 

Ioan

 


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


***This email, its content, and any files transmitted with it, are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient, please contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited.

Messages sent via this medium may be subjected to delays, non-delivery, and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. Indium Corporation does not accept responsibility for changes made to this email after is was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.***"

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