This sounds similar to a question about the solder height of LCC after reflow...about 2.5 mils in that case. I assume the connector lead joint to be similar, but it's difficult to tell because you didn't indicate the configuration or what is holding the connector body up in the first place (without solder paste). You could tell your ME the variation in distance between boards is less than the board thickness tolerance and the connector contact positioning tolerance. If you had to have a number for him, my estimation would be 1-2 mils, if it really mattered. All the connectors we work with are supported with a molded-in foot or end up "flush" to the board and that is within 2 mils of the surface. Adding 2-mils to the total connector position tolerance would be reasonable. > Rainer G. Blomberg > Honeywell -Space Systems Clearwater > Staff Production Engineer (727) 539-5534 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack C. Olson Sent: Friday, March 18, 2005 12:07 PM To: [log in to unmask] Subject: [TN] Floating SMT components? I have been asked a question that I've never read anything about before, so I'm hoping some of you assembly gurus out there will know this... We have a mechanical engineer who is trying to predict the distance between boards after soldering SMT board-to-board connectors. We know the connector mating height, but the question is: "If the connector is sitting in solder-paste, how high will it stay above the surface of the board?" Common sense tells me the connector will not be flush to the surface, there will be some solder under there, and I think we are using 6mil paste screens. Has anyone had to document something like this before? Jack --------------------------------------------------- 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 -----------------------------------------------------