Hi Chris, The normal board thickness tolerance is about +/-.007in. . Typical solder thickness as paste is about .006 in. nom. If the part floats to the top of the solder joint it will be something less than .006 or if the switch leads sink to the copper surface in the molten solder then it will be flush with the board surface... how much tolerance on the lead bend? Mounting? Brackets? Front panel? Etc... What if the board warps? I can see why you are looking for some sort of spec to refer to, however, there may not be one. I certainly am not aware of one that could help... perhaps someone else knows of something they could refer you to... but the only method I know is to fully look at ALL the possibilities and work through the math. Best regards, Bill Brooks Datron World Communications, Inc. (760)602-7004 ________________________________ From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Monday, January 12, 2009 7:19 AM To: [log in to unmask] Subject: [DC] solder thickness after reflow for tol. stackup Hello All, A mechanical designer is doing a tolerance stackup on one of our layouts and asked what we allow for the height of the solder between the board and the part. I babbled a while about how it's not that simple, then rooted around in IPC specs a while but couldn't find anything more definitive than "wetting is evident" for a value. I need to get back to him with a max value of some sort. Does anyone out there have a value they plug in for stackup analysis? We have SMT push-button switches and need to know where the top of the button will be relative to the surface of the PCB, min/max. Thanks in Advance, Chris This e-mail message is intended only for the use of the intended recipient(s). The information contained therein may be confidential or privileged, and its disclosure or reproduction is strictly prohibited. If you are not the intended recipient, please return it immediately to its sender at the above address and destroy it. ------------------------------------------------------------------------ ------- DesignerCouncil 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 DesignerCouncil To temporarily stop/(start) delivery of DesignerCouncil for vacation breaks send: SET DesignerCouncil NOMAIL/(MAIL) Search previous postings 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 ------------------------------------------------------------------------ ------- --------------------------------------------------------------------------------- DesignerCouncil 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 DesignerCouncil. To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL) Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------