Joe, Early on when we acquired our present x-ray, we did some characterization studies. We found that in general, for our machine, voids were most accurately and repeatably measured if the voltage was set so that the pcb etch patterns were still distinctly visible in the background. Too little voltage, they are dark and indistinguishable, too much and they're bloomed out. Overall for our machine, this has worked well. There are still those occasional 2D x-ray vs. 3D (5 DX) disagreements that require more focused effort (I couldn't resist the pun.) to resolve. Overall though, we encounter very few borderline situations where the x-ray setting alone is the difference between go/no-go for a part. We just revisited this issue, using a scrapped assembly with multiple voids. It was examined on our in-house 2D and 5DX, and another high-end x-ray machine we have access to. Images were captured at multiple settings on each unit. Afterward, we cross-sectioned the sites to measure the exact size of those voids and saw how they correlated with different machines and settings. Bruce Tostevin Benchmark Electronics Hudson, New Hampshire -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko Sent: Monday, April 14, 2008 3:46 PM To: [log in to unmask] Subject: [TN] Guidelines for setting voltage and current when viewing BGA x-rays All, Properly setting the voltage and current values on an x-ray machine seem to be critical in correctly viewing BGA solder connections. To high or to low will distort the x-ray image. I know that to high of a voltage results in a phenomenon know as "voltage blooming". I am looking for some general guidelines on setting a x-ray machine voltage and current when viewing BGA solder connections so a potential void can be correctly determined, measured, etc.. Thanks all. best regards, -joe --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 15.0 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 -----------------------------------------------------