Hi, Dave,
If you insist on wave soldering, my answer would be to fill the BGA via
holes with conductive epoxy at the PCB Fab stage. That way, the holes are
filled and plated over, giving a solid pad for the test probes to hit on,
without the worry of filling the holes with solder and causing shorts.
Epoxy filling would also allow the board to be sucked onto the jig.
The only note of caution is that the epoxy MAY swell slightly when exposed
to wave soldering and spoil the flat finish, so you would have to try the
first on a few boards first to see how it goes. Otherwise, you're a bit
stuck on those dilema horns.
Good Luck,
Peter
Dave Chapman <[log in to unmask]> 28/04/2003 10:02 PM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to Dave Chapman
To: [log in to unmask]
cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] BGA
Happy Monday, I have a BGA 256 Tundra which has no shorts in SMT (we
x-rayed
all 16 boards) When it goes over the wave we get a short or two. Please
assume the wave is in control.
We mask the topside of the BGA because there are a lot of vias which when
they test it would leak and not get pulled down good in the fixture. I need
the vias on the bottomside under the BGA to be filled with solder for
testing so I can't mask the bottom. What should I do?
Dave Chapman
Manufacturing Engineer
Circuit Service Inc.
---------------------------------------------------
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
-----------------------------------------------------
--------------------------------------------------------------------------
DISCLAIMER:
The information contained in this communication is confidential and may be
legally privileged. It is intended solely for the use of the individual or
entity to whom it is addressed and others authorized to receive it. If you
are not the intended recipient, you are hereby notified that any
disclosure,
copying, distribution, or taking any action in reliance of the contents of
this information is strictly prohibited and may be unlawful. Stork is
neither liable for the proper and complete transmission of the information
contained in this communication nor for any delay in its receipt
---------------------------------------------------
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
-----------------------------------------------------
|
