I think he was at 220 C because the liquidus temp of the
tin/silver/copper bga ball is 217 deg. C (not 183 C), and the intention
was to obtain a fully homogeneous mixture of the alloys, just to prevent
what is shown in the picture. It would be extremely difficult to try to
set the process window such that only a small amount of the
tin/silver/copper call dissolved into the 63/37 solder paste, you would
need to attempt a full collapse and completely melt both the ball solder
and the paste solder. In fact, if I had to solder these, I probably
would have elected to go to 230 C. with at least 70 seconds above 215.
But it depends on what the rest of the components and the pwb can stand.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joel Mearig
Sent: Wednesday, November 23, 2005 11:37 AM
To: [log in to unmask]
Subject: Re: [TN] Lead Free BGAs

The article indicates that a typical Sn/Pb profile peaks at 220degC. I
don't think anyone should be running Sn/Pb that hot. You don't need to
be 40degC above reflow to form a reliable solder joint. I think a Sn/Pb
profile should max at 205degC.

I wonder if the experimental results would change if he ran a cooler
(and in my opinion more appropriate) profile.

Joel Mearig
Delta Tau Data Systems, Inc.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
Sent: Wednesday, November 23, 2005 7:07 AM
To: [log in to unmask]
Subject: [TN] Lead Free BGAs

>       Tin/Silver BGAs balls forces oven profiles to be increased so 
> that the ball collapses and creates a good SJ when using tin/lead 
> solder, according to this article.
>       Regards,
>       Ramon
>
>
>               http://www.empf.org/empfasis/jan05/help0105.htm

---------------------------------------------------
Technet Mail List provided as a 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/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 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/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 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/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------