Tom, both Rev B and C to 610 had so many words associated with solder ball criteria that it's hard to see the real requirements. Rev D will be much clearer with the following: 5.2.6.1 Soldering Anomalies - Excess Solder - Solder Balls/Solder Fines Solder balls are spheres of solder that remain after the soldering process. Solder fines are typically small balls of the original solder paste metal screen size that have splattered around the connection during the reflow process. Target - Class 1,2,3 * No evidence of solder balls on the printed wiring assembly. Acceptable - Class 1,2,3 * Solder balls are entrapped/encapsulated.. * Solder balls do not violate minimum electrical clearance. Note: Entrapped/encapsulated/attached is intended to mean that normal service environment of the product will not cause a solder ball to become dislodged. Acceptable - Class 1 Process Indicator - Class 2,3 * More than five solder balls per 600 mm2 [0.93 in2]. Defect - Class 1,2,3 * Solder balls violate minimum electrical clearance. * Solder balls are not entrapped in no-clean residue or encapsulated with conformal coating, or not attached (soldered) to a metal surface, Figures 5-45 through 5-48. Note that there are really only two considerations--the solder balls aren't loose or aren't likely to break loose in the normal service environment, and they aren't of a size or location that will cause a short or violate minimum electrical clearance. It's no difference from the criteria in Rev C, just stated much clearer. I hope this helps. Jack Jack Crawford, IOM IPC Director Certification and Assembly Technology [log in to unmask] NEW PHONE 847-597-2893 NEW FAX 847-615-5693 IPC HAS MOVED- NEW ADDRESS: 3000 Lakeside Drive, Suite 309 S Bannockburn, IL, 60015 New main Phone 847-615-7100 New main fax 847-615-7105 Check www.ipc.org/move for new staff phone numbers. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Gervascio Sent: Monday, October 04, 2004 1:56 PM To: [log in to unmask] Subject: [TN] solder balls wedged under low profile SMD Are solder balls a defect or process indicator? The solder balls were are observing are mid chip solder balls on low profile SMD resistors and caps. The mid chip balls typically wash off and X ray does find a few solder balls wedged under SMD devices (right now about 8 per board). I think they are process indicators and do not need touch-up (I really think desoldering the part and resoldering the part is more deleterious to reliability than these entrapped solder balls. I went over the IPC-A-610C and found the following pertaining to solder balls. Para 6.5.3.1 and Para 12.4.10 Excess solder. Target condition is no evidence of solder balls on the printed wiring assembly Acceptable condition Class 1/Process Indicator Class2,3. Entrapped or encapsulated solder balls that are within 0.005 inch of lands or conductors, or exceed 0.0051 inch in diameter. Tom Gervascio Senior Process Engineer Sparton Electronics (352) 540-4040 --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------