Sender: |
|
X-To: |
|
Date: |
Tue, 17 Apr 2007 18:51:05 +0200 |
Reply-To: |
|
Subject: |
|
From: |
|
Content-Transfer-Encoding: |
quoted-printable |
In-Reply-To: |
|
Content-Type: |
text/plain; charset="iso-8859-1" |
MIME-Version: |
1.0 |
Parts/Attachments: |
|
|
Hi Werner,
We tried globtops on the corners many years ago, but we found that the
registering became disturbed during wave soldering (superBGAs). Since
then we have shipped 2 million boards with BGAs with no corner fixation.
When/why do some need these extras?
Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Werner Engelmaier
Skickat: den 17 april 2007 17:32
Till: [log in to unmask]
Ämne: Re: [TN] Tacking corners of BGAs
Hi Richard,
The improved reliability should not have come as a surprise. Consider
what is
happening:
(1) the solder balls are at their full diameter when BGA is placed,
(2) the epoxy fixes the distance between PCB and BGA at that diameter
value,
(3) during reflow, the epoxy expands opening the solder gap further,
(4) on cooling, that solder balls are prevented by the epoxy from
collapsing,
(5) you have the equivalent reliability of using non-melting 10Sn90 Pb
solder
balls,
and (6) this results in the reliability improvement observed.
I have been pushing this for ceramic chipp components for some time.
Werner
**************************************
See what's free at http://www.aol.com.
---------------------------------------------------
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
-----------------------------------------------------
|
|
|