Gottcha! Thanks Werner - and a good point to remember. I guess ramp rates
will have to come down to accommodate the thermal inertia, without
over-cooking other components - or we're going to have to come up with all
kinds of masking or shielding ("sun shade") requirements and techniques.

Thank goodness the lead-free zone hasn't expanded as far as Singapore yet
(except for US customers).

Peter



Werner Engelmaier <[log in to unmask]>    12/11/2002 12:20 PM
Sent by: TechNet <[log in to unmask]>

Please respond to "TechNet E-Mail Forum."; Please respond to Engelmaier

              To:  [log in to unmask]
              cc:  (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
              Subject: Re: [TN] profiling BGAs








Hi Peter,
You are right, 'the reason why one drills up into the central ball of a BGA
to place a T/C, is because it's these central contacts that generally
suffer
from insufficient heating owing to the shading effect of the overlying body
of the component.'
The question I answered was how to determine the temperature of a component
body. This will be even more important given the idiotic drive towards
lead-free solders, when solder reflow temperatures need to be higher and
thus
component temperatures as well. Thus, knowing the component temperatures
will
be even more important than now.

Werner Engelmaier

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