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EEVblog #1037 – Solving Ceramic Capacitor Cracking

EEVblog #1037 - Solving Ceramic Capacitor Cracking



Dave demonstrates various practical PCB and component selection solutions and techniques to prevent flex stress cracking of Multi Layer Ceramic Capacitors (MLCC) on PCB's and preventing your product from catching on fire!
Open Mode capacitors.
Flexible Endcap Soft Termination Capacitors
Lead Frame Capacitors
Series Capacitors

TDK Solutions for Ceramic Capacitor Cracking
https://product.tdk.com/info/en/products/capacitor/ceramic/mlcc/technote/solution/mlcc02/index.html#anc01

Soft Termination:
https://product.tdk.com/info/en/catalog/datasheets/mlcc_commercial_soft_en.pdf

Open Mode: https://product.tdk.com/info/en/catalog/datasheets/mlcc_commercial_openmode_en.pdf

AVX Flexiterm:

Flexible Terminations – Automotive MLCC with FLEXITERM®

Kemet Flex Termination
http://www.kemet.com/Lists/ApplicationBriefs/Attachments/58/Flexible%20Termination%20Technology%20(FT-CAP).pdf

Forum:...

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List your electronic components at BuySellComponents.com

Tags: smd capacitors

About the Author

50 Comments

  1. Date: November 10, 2017 at 00:08
    Author: erica

    "university of maa-ree-land"
    as someone who lives in maryland… why…

  2. Date: November 10, 2017 at 00:48
    Author: Johannes Jung

    You should turn the audiolevel up. Here at absolute max. in a Linux System with volume overload on my headphone its actually not loud enough. Sorry for my bad english. I'm German 🙂

  3. Date: November 10, 2017 at 01:38
    Author: Rtzz0

    woah, time to grind some MLCCs and look at them under the microscope

  4. Date: November 10, 2017 at 03:08
    Author: Fir3Chi3f

    I might never find this useful, I did find it interesting though! Thanks Dave!

  5. Date: November 10, 2017 at 03:59
    Author: Bernd Felsche

    Structural hint: If you need a connector on the board, consider a straddle-mount on the edge. The spacing and length of pins of some through-hole connectors are amenable to straddle mounting onto surface-mount PCBs. [ Don't expect automagic assembly machinery to cope with soldering the connector.] Twisting of the connector can still impose stressses.

    Structural trickery by milling slots is to have only narrow bridges for traces between any connectors and the other components on the PCB. The strain (deflection) of the PCB is isolated as the narrow bridges are more flexible and will stretch accordingly with the more rigid part of the PCB on the other side of the bridge. Keep in mind that that extra flexibility means more flexing; which can be an issue in applications subjected to vibration.

    Some connectors such as Molex's MX123 series convey the intent to (rigidly) support the board only by the connector'pins, with the connector housing rigidly connected to the housing. Any strain at the connector due to the harness being (dis)connected or moving otherwise is thus largely contained. The tiny residual strain produces only a small movement of the attached PCB. Environments subject to vibration or shock still require some stress and strain analysis due to the inertia of the PCB and the components soldered onto the board. A thicker PCB substrate can save your bacon.

  6. Date: November 10, 2017 at 12:59
    Author: Suraj Grewal

    It they can simply ship incomplete boards with through hole capacitors for user to solder

  7. Date: November 10, 2017 at 16:33
    Author: Maxime Thibault

    I had a similar problem a few years back. The burn glass fiber was conductive and red when power apply. i used a alumina sand blast (pen style sandblaster) to remove all the burn area and fill the hole with regular epoxy i even place back the pad on top of the epoxy and solder the capacitor on the pad. The equipment is still working.

  8. Date: November 10, 2017 at 16:56
    Author: The Kaveman

    The initial thought is that its a capacitor manufacturer issue ..by the time you add flex , pcb flex , thermal differences , manufacturing process, it has such a disastrous consequence of fire it really has to be dealt with better in production of capacitor such as a flexible factor in ceramic construction or fail safe design. perhaps the caps should have legs like a silicon chip to absorb stress of pcb and also thermal

  9. Date: November 10, 2017 at 17:39
    Author: Szoszaty

    "I woffled on long enough about… cracks" LOL

  10. Date: November 11, 2017 at 05:46
    Author: PETMK

    On the current product I developing I have another method for it. As I'll use a custom plastic there is a plastic "bed" where the critical parts of the PCB is laying. Especially terminals. It's in price of the custom plastic and there are no expensive capacitors needed.

    But there is another risk. A have seen a bad fixture in the mass production. I thin there was a HP7030 used for the ICT testing and it pressed the PCB too close to the power suppply. It has about 0.5% to crash the cap Unfortunatelly there were three lines and four slots in each ICT so it takes some time before we found it.

    But the MLC is not the one component sensitive to bend the PCBs. My first job was servicing the mobile phones and there was a legend of unreability. Sagem MC9xx. It has thin, multi-layer PCB. It was mounted by few screws to the chassis on the edge. Un bottom side there was a CPU and memories in 0.4mm BGAs, covered by soft, metalized plastic. On the top side there were the rubber buttons keyboard. If you press 5, the BCB was bent 0.7mm down in the center… It usually dies in two months (Sagem technician said they did 6k units for Sagem and in two months 5k of them were back). Sometimes helped to reflow the boards again but you have to drying the PCB for three days as some components dislike moisture…
    Later they uses epoxy to fix the BGAs. The phone lives three months and there was no easy way to fix it… :Q

  11. Date: November 11, 2017 at 09:45
    Author: Baspro

    Thanks for the invaluable information you present, Dave!

  12. Date: November 11, 2017 at 16:15

    Stress = load / area , i.e. pressure. The correct term to use is probably Strain, which is change in length / original length.

    Nice video, thanks.

  13. Date: November 11, 2017 at 17:53
    Author: Arek R.

    Now I will be worried about every capacitor…

  14. Date: November 11, 2017 at 18:57
    Author: zokonjazokonja

    I would like to add additional info about this topic, SMD capacitors should not be soldered with hot iron because it can cause thermal cracks inside ceramic structure because of rapid temperature change. Best way is to use reflow oven if you have it, next option is hot air soldering, worst option is hot iron. I think that some SMD MLCC producers highlight this, I know that Epcos did.

  15. Date: November 11, 2017 at 20:16
    Author: Dreamagine1

    Syfer datasheet: "MLCC Capacitors" = "Multi Layer Ceramic Capacitor Capacitors"

  16. Date: November 12, 2017 at 04:29

    Ahhhh crap. When I put in my motherboard I remember hearing a "crack". Its running fine right now but…..what if that was a cap. O_O

  17. Date: November 12, 2017 at 14:04

    Still don't understand why, on such a possibly dangerous component in terms of fire, there isn't just a simple, cheap fuse in series. I mean, when the capacitor is designed to handle, say 0.1 Watts thermal, what reason could there possibly be to let it try to happily burn away 1000 Watts electrical?

  18. Date: November 13, 2017 at 02:55
    Author: guillep2k

    This is the kind of videos I reeaaaally like. Thanks, David!

  19. Date: November 13, 2017 at 15:53
    Author: Yoram Stein

    Hello Dave Shenzen market offer left overs from production lines and  out of specs. series a manufacturer that respects himself does not purchase there!

  20. Date: November 13, 2017 at 19:56
    Author: CNe7532294

    Thank you for this Dave. We need more awareness on things like this. It is my hope that soft terminations or something even more impressive becomes the gold standard. Sure demand gets driven up immediately and along with that comes price. However, just like side airbags and ABS we may see this in such high demand that output will try to match up to it. In other words, it should become cheaper in the long run. After all, who wants a product that can catch on fire.

  21. Date: November 13, 2017 at 21:03
    Author: chancho00

    When you have to check every tab on the browser to see if you find a meme.

  22. Date: November 13, 2017 at 21:07
    Author: rchandraonline

    wow. Qty. 1, $0.21 vs $0.05. At least qty. 25 it's $0.083 vs qty. 10 $0.04, so closer to the 2:1 ratio.

  23. Date: November 14, 2017 at 02:42
    Author: Alex Davis

    Hey Dave, you mention changing output voltage from references due to board stress, but it's also worth noting that things like op amp offset voltage can be affected as well. In most general-purpose cases, this isn't too much of an issue, but in very high precision applications, it can be a big deal, especially if you get board flex due to thermals. Good video, and very informative!

  24. Date: November 14, 2017 at 03:11
    Author: widgity

    It annoys me that I have learned far more useful electronics from this channel than I did from my electronics degree :/

  25. Date: November 14, 2017 at 23:38
    Author: Matjaž Kajba

    how about the two capacitor technique and micro-phonics? could you use the technique so that micro phonic effect of two caps would cancel out?

  26. Date: November 16, 2017 at 03:00
    Author: Heider Marconi

    Hi Dave!! Great channel!! But I have a question about using 2 capacitors in series : what happens to the DC voltage between them? It should be very high impedance. Is this a problem? Have you ever heard of issues because of this? I am an integrated circuit designer and that is the kind of trick I would be afraid of using on chip. Thanks for the video! Great discussion!! Cheers! Heider

  27. Date: November 16, 2017 at 15:19

    Learned this 1 Year ago at university
    Very interesting, that i learned something that coveres real world Problems

  28. Date: November 17, 2017 at 00:27
    Author: GigaVolt

    Hi Dave, Great video. At 24:24 you mention that the 3 stars mean the most expensive. The stars are from an engineer's perspective and are meant to represent lowest cost.

  29. Date: November 17, 2017 at 03:49
    Author: Condot Maroddi

    What about that one guy on his website who said ALL capacitors have polarity. That is to say, ALL capacitors have a negative and a positive and it is up to the installer to ascertain and apply the correct polarity. Any truth to it? Mr. Carlton is his name.

  30. Date: November 25, 2017 at 13:35
    Author: Leo Comerford

    16:02 Apparently the somewhat ropey and by now quite aged capacitor you find connected between live and neutral in old valve amplifiers is affectionately known as the "death capacitor".

  31. Date: November 26, 2017 at 08:01

    great informative video ! one another possible crack cause is wrong setup in pick and place machine. normaly a pnp machine needs to know component height. many operators doesn't care or bother to check different caps for heights. they just use simple template for 0603, 0805 etc. but in reality 100nf/0603 and 1 uf/0603 caps are in different height. so if pnp machine pushes a little bit much that cap to the pcb. that can cause stress cracks or become more sensitive for future stresses on the pcb.

  32. Date: December 20, 2017 at 17:58

    One way of reducing mechanical stress is by mounting the capacitor perpendicular to the likely bending forces as Dave showed, that way the bending force is more on the pads than the capacitor itself. Also good design practices suggest adding more mounting points if you have heavy components on a PCB.
    Also you can get MLCCs in a reversed connection, where the long sides are where the pads are. These are also good for extremely low ESR and inductance.

    One big trap is also the voltage rating of MLCCs. Some dielectric materials can cause dramatic drops in capacitance dependent on voltage.

    Also, I don't like those MLCCs with metal wings on them, they are so expensive! I suppose if I was making something for high reliability, it would be worth it. But in a regular consumer product, not so much.

  33. Date: January 22, 2018 at 16:41
    Author: maelgugi

    So much I didn't know, so little time. I do now comprehend Fausto.

  34. Date: January 26, 2018 at 03:33
    Author: Dave

    Why do they go through the hassle of photo etching PCBs an not simply print them directly onto a sub strait using conductive ink? Or simply rout them on a cnc?

  35. Date: February 21, 2018 at 11:42
    Author: Fried Mule

    I think I have read that, where the board could be under severe stress, like bump and shaking, they sometimes mounted an insolating fiberboard under the pcb.
    Does that sound right?

  36. Date: February 25, 2018 at 16:22
    Author: Tom Walter

    Great Video. First time I came across mechanical stress into a package was with a Switched Capacitor Filter. MF10 around 1984.

  37. Date: March 31, 2018 at 14:19
    Author: hifatpeople

    I came here wondering how to lay out flex pcbs lol, and instead find a video on the difficulties of avoiding things breaking from boards that arent meant to flex

  38. Date: May 15, 2018 at 16:32
    Author: Lunas Eclipse

    Move them to a point not under such stresses or use a ceramic disc cap vs smd cap for that spot… put extra support for the terminals or put the terminals on a lead not attached to the board…

  39. Date: May 25, 2018 at 13:19
    Author: Eric Wrenfrow

    That would be a transverse stress/load you have to worry about as opposed to a longitudinal. Transverse is usually the one you have to worry about.

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