Any option must be known good before hardware is designed. I don't design for the trash can. Am aware of BT material option. We are currently ceramic with no problems, with much push from high-priced-help to migrate to FR4 ' like everybody else'. Of course there are no concrete examples of SMD in FR4 forthcoming, but that doesn't reduce push from above. They would need a documented disaster story to decide that they knew, all along, it was a bad idea. Question is to actual performance of FR4 modules with dims equal to or exceeding 2inches on one side. Any feedback of simple successes/niggling problems? Is 0.1millimeter/ .004inch achievable and how? RL ----- Original Message ----- From: Earl Moon <[log in to unmask]> To: <[log in to unmask]> Sent: Monday, January 21, 2002 5:24 AM Subject: Re: [TN] FR4 power module SMC coplanarity > First let me say Eric must know the lady about whom I speak. Ouch! > > Concerning a more vital, doubt it, issue, there is no reason to expect the > PCB version, on whatever material, will go out of whack like a potato chip. > BGA's are built on BT based boards and they stay reasonably flat. > > You know it depends on how well the design was effected. You know - balance, > construction, etc. > > Just have to try them and see. If they do warp, what are your options? > > MoonMan > > -------------------------------------------------------------------------- ------- > 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 e-mail to [log in to unmask]: SET Technet NOMAIL > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > 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 > -------------------------------------------------------------------------- ------- > --------------------------------------------------------------------------------- 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 e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest 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 ---------------------------------------------------------------------------------