Content-Transfer-Encoding: |
quoted-printable |
Sender: |
|
Subject: |
|
From: |
|
Date: |
Wed, 25 Jul 2001 20:07:03 +0800 |
Content-Type: |
text/plain; charset=iso-8859-1 |
MIME-Version: |
1.0 |
Reply-To: |
|
Parts/Attachments: |
|
|
Hello Friends,
Can anybody explain why there is always a non-reflow
of solder paste as shown by the drawing below?
(Embedded image moved to file: pic07711.pcx)
The solder paste used for assembly was
88Pb10Sn2Ag and it is an Indium No clean paste.
Its liquidus temp was 290 C and solidus temp of 268 C.
Reflow Atmosphere: N2 purge as hot gas and cool gas (shown at the above
drawing)
although we tried to increase the temp to over than 300 C, it is still the
same results.
I tried the paste to other oven with a forming gas blanket, and reflow it
to a peak of 295 C
the results were good (All reflowed).
We had profiled the above oven at 3 points Left edge, Midle and. Right edge
and
temperature difference vs setting was ± 5 degree C on that three points.
Was the non-reflow due to the blanket? O2 ppm level? But why on the left
side only?
Does a localized heating have occured? But the temp profile was okay?
Do you have any insights that you can share?
God Bless You All...
Thanks
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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
---------------------------------------------------------------------------------
|
|
|