From the list given I believe that the X here is the same as your mathematical unknown. I represents any solder constituent with the exception of Bi, which is handled by the separate category (e6) So alloys such as Sn3.5Ag0.74Cu0.21Zn would be covered in the e5 category. Jeffrey A McGlaughlin, CID Engineering Designer Systems Development Engineering Services Room 4-2-50 Phone (614)424-7582 -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of James Jackson Sent: Monday, March 18, 2013 10:12 AM To: [log in to unmask] Subject: [DC] IPC-1066 Question In looking through the IPC-1066 document (Rev ? - January 2005), in 5.1 Solder Finish Categories, there are several 'e' categories that can be added via labeling, to an assembly. I am not sure what 'X' is (well, in math, it's an unknown). For example, e5 - SnZn, SnZnX (no Bi) Sn = Tin Zn = Zinc X = ??? Has the periodic Table of Elements just recently added a new element called 'X'? What am I missing here? The closest that I can find might be Xe - Xenon, but I would think that would have been stated as such. It is not only in the e5 category, it is also in the e2 category. I want to understand this. I know that many jokes can (and - knowing this group - will) be made about this... I can think of a few myself. I have to show this IPC labeling spec to my manager, and if he asks me and I just shrug my shoulders and give an "I dunno..." answer, I won't look too intelligent (it don't take much). If this is a goof on the part of the IPC - it don't make them look too good either. I'm sure that it is something that I am overlooking, and I will be told shortly what it is. Thanks for any serious (and... I suppose the not-so-serious) input on this. Regards, James Jackson Oztronics ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------------------------------------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0. 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) For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 --------------------------------------------------------------------------------- ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------------------------------------- DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0. 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) For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ---------------------------------------------------------------------------------