Hi Doug! OSP surface finishes are great in many situations, however, there are some assembly thermal profiles which an OSP just can not withstand. We process several Class 3 assemblies which require long multiple bake cycles due large heatsinks and other pwa design issues which results in the breakdown of the OSP and a loss of solderability. OSP surface finishes are just one of the finish "tools" in the toolbox and unlike the traditional HASL finishes, the new alternative surface finishes are not a "one size fits all" selection. Immersion tin is more robust to thermal degradation due to it being a metallic finish. Additionally, I am no fan of thiourea but a properly run immersion tin plating bath is not hazardous to the operators nor the planet. OSP surface finishes should be utilized where possible but they will not work in all situations. Dave Hillman Rockwell Collins [log in to unmask] Dougal Stewart <[log in to unmask]>@ipc.org> on 08/29/2002 03:58:40 AM Please respond to Dougal Stewart <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: Re: [TN] Talk to me about Omikron White Tin board finish, please. I still don't understand why you assembly people don't use OSP ! It is the easiest process to use in bare board fab, it is reworkable at the fab house, if you have kept the parts on a shelf for too long and are suspicious that they may not solder so well, you can send them back to the FAB for reprocessing (assuming they have not gone bust meantime, or moved half way around the planet) and you are not contributing to polluting the planet with Thiourea, or killing the board shop operators ! So what has white tin over OSP? Dougal Stewart email: [log in to unmask] phone: +44 1896 822204 mob: +44 7984 629667 ----- Original Message ----- From: "Jason W. Gregory" <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, August 28, 2002 11:03 PM Subject: Re: [TN] Talk to me about Omikron White Tin board finish, please. > Barbara, > > I love white tin! It is absolutely, positively my favorite finsih. The flatness, > which is it's main attribute, is perfect for fine pitch, 50mil and lower, and > the wetting characteristics are superb. The only downside is the thiurea (sp?). > Apparently it's pretty toxic and carcinogenic. I'm sure Brian Ellis will chime > in soon (I hope). > > Jason Gregory > Production Supervisor > LaBarge Inc. > (918)459-2367 > [log in to unmask] > > > > > Barbara Burcham <[log in to unmask]> on 08/28/2002 01:29:06 PM > > Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to > Barbara Burcham <[log in to unmask]> > > To: [log in to unmask] > cc: (bcc: Jason Gregory/LABARGE) > > Subject: [TN] Talk to me about Omikron White Tin board finish, please. > > > > Who is using this and is it working for you? > What do y'all think about the "Omikron" process as opposed to other White Tin > applications? > Is one better than the other? > > Barbara J. Burcham, C.I.D. > Sr. PCB Designer > Fairfield Industries > Sugar Land, TX 77478 > 281-275-7687 Work > 281-275-7550 Fax > [log in to unmask] > > -------------------------------------------------------------------------- ------- > > 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 > -------------------------------------------------------------------------- ------- > > -------------------------------------------------------------------------- ------- > 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 > -------------------------------------------------------------------------- ------- > --------------------------------------------------------------------------------- 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 --------------------------------------------------------------------------------- --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------