Electronics Forum | Mon Dec 26 12:18:55 EST 2005 | mariss
That seems to be the case. We are replacing the X7Rs with C0Gs for future production as a work-around. X7Rs are sold so I assume they can be used succesfully; is it just they shouldn't be used in mixed SMT / thru-hole designs? Mariss
Electronics Forum | Mon Dec 26 12:21:15 EST 2005 | davef
Sure, you can use X7R dielectric ceramic capacitors on mixed technology boards. You need to be aware of the limitations and design and control your process appropriately. Continuing: * BIG cracks show as hard failures * Small cracks show as a leakag
Electronics Forum | Tue Dec 27 13:53:57 EST 2005 | Cmiller
I would assume you are using a depanelizer to cut the boards apart? If not you should be wheather its causing your current problem or not.
Electronics Forum | Tue Dec 27 19:15:02 EST 2005 | PWH
Agree with Cmiller. We had a similar prob. with some caps. on a v-scored array. We bought a pizza cutter depaneliser and the problem reduced. It's a "FKN Systek" if you want to look at models.
Electronics Forum | Thu Dec 29 08:53:20 EST 2005 | Cmiller
John brings up a good point. We have seen that problem with an axial inserter. Why someone would put SMT caps on bottom and TH resistors on top is beyond me but it but we do see it.
Electronics Forum | Mon Jan 02 23:50:24 EST 2006 | grantp
Hi, Just wondering while reading this thread, would 0402 caps be more immune to stress because they are smaller? Regards, Grant
Electronics Forum | Wed Jan 04 02:54:25 EST 2006 | Slaine
Hi, Id like to see the photos if possible, you can tell a lot from cross sections and the shape of the crack if you have any. timlivesey@netscape.net
Electronics Forum | Wed Jan 04 13:13:41 EST 2006 | mariss
It was suggested that a delay between reflow and washing the boards (hours?) would allow the water soluable flux residue to somehow damage the X7R capacitors. I'm wondering if that makes sense at all? Mariss
Electronics Forum | Mon Dec 26 19:18:49 EST 2005 | arnold
I would to ask on what do you call on the color green contamination found on the soldered units. Whe i soldered some units after few days there was a color green on the wires. what do you call on this contamination?
Electronics Forum | Mon Dec 26 20:36:20 EST 2005 | davef
Look here to get started: http://www.smtnet.com/forums/Index.cfm?CFApp=1&Message_ID=38261