TECHNET Archives

December 2002

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Macko, Joe @ IEC" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Sat, 28 Dec 2002 08:43:41 -0800
Content-Type:
text/plain
Parts/Attachments:
text/plain (28 lines)
TechNets,

Many of our boards are densely populated, double sided, multilayered with
BGAs on both sides.   Side 1 is populated and reflowed, then side 2 is
populated and reflowed.  Side 1 therefore sees 2 reflows which appears to
make the surface of the solder balls on the BGAs reflowed twice appear
grainier after the 2nd reflow.   A water soluble flux based Sn 62Pb36Ag02
solder paste is used.  We have also tried using Sn63Pb37 alloy.

Has anyone else experienced similar problems with densely populated, double
sided boards where one side sees 2 reflow cycles?  Is there a practical
solution for maintaining BGA solder ball appearance thru the 2nd reflow?
Reflowing in a nitrogen environment is not an option.

Happy Holidays
joe

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

ATOM RSS1 RSS2