Electronics Forum | Thu Feb 03 07:39:24 EST 2005 | davef
The component orientation was just for the calculation. It has no affect on what you're seeing. As an alternate explanation, it's possible that difference in temperature is causing the board to flex in the z-direction [as you say, it may not be f
Electronics Forum | Wed Feb 02 20:00:48 EST 2005 | davef
150*C/min * Determining the distance it takes to lower the delta temperature at the current conveyor speed: [150*C/min]/[25 inch/min] = 6*C/inch * Calculating how much of this 6*C/inch would be spread along the length of the 0805 capacitor: [6*C/inch
Electronics Forum | Thu Feb 03 10:01:08 EST 2005 | Philj
Try heating a blank board on a hotplate to 183 deg C. with a board this thick, if the layer construction is poorly balanced, it may bend enough in the region of the ceramic capacitor for the soldered joints to crack it on cooling to ambient.
Electronics Forum | Wed Feb 02 08:51:25 EST 2005 | Dougs
we have a capacitor cracking on one of our boards, there are four of the same cap on the board and only one cracks, we are seeing about 6% of the component cracking. it's not near the edges of the board and he board is 2.4mm thick so i dont think it
Electronics Forum | Thu Feb 03 12:21:15 EST 2005 | Chunks
Lets get to the simple things. Wave or Reflow? Wave soldered parts have a higher susceptibility to physical damage until they are waved. That�s were I normally see this type of break. Usually, the crack is a circular pattern in the cap if it�s fr
Electronics Forum | Wed Feb 05 10:51:17 EST 2003 | bradlanger
Thanks for responding. Do you think I could have my oven profile too aggressive
Electronics Forum | Tue Feb 04 14:05:10 EST 2003 | bradlanger
I am haveing some trouble with ceramic capacitors breaking on a couple of boards I am running. The boards I have trouble with are in a 6 up and 12 up array and the caps are near the score lines where the individual boards are broken apart. Has anybod
Electronics Forum | Sat Feb 15 06:40:14 EST 2003 | Hans Koerner, Germany
It is a serius problem with that mulilayer ceramic caps! In automotive applications you have to use 2 in series for one single cap. During depanelizing you create a mechanically wave in the board, so 3.. 4 mm. Best way is not to do such a wrong desig
Electronics Forum | Fri Feb 28 10:02:39 EST 2003 | bradlanger
Thanks for all the input on this thread. My company bought an FKN depanalizer and that solved our problem. I am also working with our design engineers on laying out the boards without the caps near the edges.
Electronics Forum | Fri Feb 28 16:23:39 EST 2003 | genny
If you can't get rid of all caps near the edges, don't forget Neil's advice above regarding parallel vs. perpendicular. I have seen a 90 degree rotation make a huge improvement in the reliability of some caps.
