Capacitor damage  - Page 1
Forum section: electronics / general

author: Hans Mortensen
author_rank: Contributor
timestamp: October 13, 2022, 09:28:53 pm
content: We recently had some boards come back with dished in tops, but only some of them and the rest of the board components look great.We were wondering if this could be from the pick and place machine and what settings would even cause this type of damage!Or if not, has anyone seen damage like this?

author: ogden
author_rank: Super Contributor
timestamp: October 13, 2022, 09:52:55 pm
content: It looks like imprint from P&P nozzle, caused by P&P component setup (height) mismatch. You shall ask P&P operator to verity dimensions in the P&P setup compared to dimensions of actual component.  Tho I wonder why it is off-center

author: Clif
author_rank: Newbie
timestamp: October 14, 2022, 07:06:37 am
content: if this damage caused by pick&place machine, why the other one looks OK? this 2 capacitors may have same mounting parameter

author: Gyro
author_rank: Super Contributor
timestamp: October 14, 2022, 08:15:17 am
content: Is it always the same capacitor location on different boards?

author: jmelson
author_rank: Super Contributor
timestamp: October 14, 2022, 04:04:38 pm
content: Looks like a square nozzle on a P&P machine. My old machine could do this if the feeder got out of sync with the pick-up. For 12 mm wide tape parts, the head had to do two strokes to advance 8mm part pitch components, and 3 strokes for 12mm pitch. For it to work as designed, the component woud advance to the pick-up position on the next to last stroke, and then be lifted by the nozzle on the last stroke. If the tape was out of sync, the nozzle would pick tha part on the PREVIOUS stroke, and then mash the part back onto the feeder or tape, next-up part, and dent it. These caps are almost surely 8mm or 12 mm part pitch, so several sprocket holes between parts. The machine picked up a part with the tape pocket not properly aligned and then brought it down on another part with enough force to dent it.What type of P&P machine are they using? Seems pretty low-tech to not detect a fault when this is happening.Jon

author: Hans Mortensen
author_rank: Contributor
timestamp: October 14, 2022, 07:06:40 pm
content: Quote from: Gyro on October 14, 2022, 08:15:17 amIt varied by board, but most of the damage occurred on these 2 capacitors and not always the same one.

author: Hans Mortensen
author_rank: Contributor
timestamp: October 14, 2022, 07:24:56 pm
content: Quote from: jmelson on October 14, 2022, 04:04:38 pmThanks for your insight on this!That sounds very plausible with the randomness of the marks and as noted above by Ogden how off center the marks are. I will have to see what our CM comes back with, so far, it's been a bit of side stepping, but they are good folks, and we will eventually get a reason I'm sure.I don't know what the model or manufacture is, I will have to ask them. They stated that they are using a foam tip that would break if too much force was applied.I did some tests on the capacitor shells, and they are very soft and easy to dent, even with mild force. I figure that this level of force may not damage the machine or even provide much feed back for software to catch.Regards,Hans

author: Mangozac
author_rank: Frequent Contributor
timestamp: October 16, 2022, 04:46:12 am
content: Looks to me like handling damage. Is there nothing on the bottom side of the PCB that corresponds to that square shape?

author: jmelson
author_rank: Super Contributor
timestamp: October 16, 2022, 03:14:36 pm
content: Quote from: Mangozac on October 16, 2022, 04:46:12 amWOW! I think you have got it! Most P&P nozzles are round, and it would take a fair amount of force to dent caps that I have around here.So, mashing a stack of boards together is a much more likely cause. Do these boards have components on both sides? I almost see where the dents look like the solder lands of large ceramic caps on that dented cap.Jon

author: Hans Mortensen
author_rank: Contributor
timestamp: October 17, 2022, 08:13:53 pm
content: Quote from: jmelson on October 16, 2022, 03:14:36 pmI'm uncertain how this would occur... the PCBs were well-packed, and underside components don't seem to be in the correct positions to cause these imprints. But this might explain the randomness of it, and some of the shorter capacitors were slightly indented.we are still going through the process of figuring this one out.Regards,Hans

author: ogden
author_rank: Super Contributor
timestamp: October 18, 2022, 08:51:10 pm
content: Quote from: Hans Mortensen on October 17, 2022, 08:13:53 pmDont you find it strange that shorter capacitors can be "reached" by improper PCB handling? - I do not buy this explanation. First I would state that there will be no consequences for assembler regarding prior damage to production, then check specs of all P&P nozzles used, compare to imprint. Such way narrowing -down search significantly.

author: ogden
author_rank: Super Contributor
timestamp: October 29, 2022, 09:23:42 pm
content: Any update regarding this case?

author: Hans Mortensen
author_rank: Contributor
timestamp: March 20, 2023, 11:00:06 pm
content: Not really, they fixed the damage, but we never got a really satisfactory answer. Thanks for all the great suggestions, guys!