because most components are specified for meeting temp shocks
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: den 7 januari 2008 19:30
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] Reflow profile development - correct starting temperature for evaluating TAL using non-eutectic solders
Absolutely true. I recently took over the VP process here, and I am beginning to like it more and more. I was worried about the thermal shock inherent to the process, but it does not seem to be as big of a reliability issue as I thought it would be.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord
Sent: Monday, January 07, 2008 11:56 AM
To: [log in to unmask]
Subject: [TN] SV: [TN] Reflow profile development - correct starting temperature for evaluating TAL using non-eutectic solders
To build on Richard's comments, we also make difference between wave soldering, IR, VP and hand soldering. E.g. with VP, no risk of oxide formation, no dross, near instant liquidus etc, we use little lower top temperature, which many components like.
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Stadem, Richard D.
Skickat: den 7 januari 2008 18:14
Till: [log in to unmask]
Ämne: Re: [TN] Reflow profile development - correct starting temperature for evaluating TAL using non-eutectic solders
To build on Werner's comments, understand that you must be in total liquidus for wetting dissolution (IMF formation) to take place. No real wetting takes place in the plastic range between 179 and 189 C. The difference is somewhat irrelevant, as you should really be above at least 189 (liquidus) plus 20C as Werner stated. So your TALT should begin at 209C ramping up and again ramping down. You really do not need to have this TALT be longer than 15 seconds or so for good wetting on the coolest solder joint on the assembly, even on ENIG. If this means having a TALT longer than 120 seconds on the hottest point, then make sure you use nitrogen else if the solder is held in liquidus for that long of a time some oxidation begins to occur (just like the dross formation on your wave solder or tin pot) and you get overheated, flux-starved solder joints.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier /*
Sent: Monday, January 07, 2008 10:56 AM
To: [log in to unmask]
Subject: Re: [TN] Reflow profile development - correct starting temperature for evaluating TAL using non-eutectic solders
Hi Joe,
Unfortunately, a natural outcome of a proper reflow profile has become a parameter to be aimed at. TAL is NOT a proper reflow parameter, and assures in and of itself not good wetting and metallurgical bonding.
Adequate solder joint quality is assured with achieving Liquidus+20 C for 5 seconds at the slowest heating solder joint in the assembly. So whatever the Liquidus temperature is for your solder alloy +20 for 5 seconds. For eutectic SnPb that means 203C for 5 seconds at the slowest heating solder joint, which of course means everything else on the assembly will see higher peak temperatures for longer times [except for vapor phase, of course].
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
**************
Start the year off right. Easy ways to stay in shape.
http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489
---------------------------------------------------
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
-----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
|
