MLCC placed on their lateral side - how critical would that be? - Page 1
Forum section: electronics / general

author: RoGeorge
author_rank: Super Contributor
timestamp: April 16, 2018, 05:00:43 pm
content: AFAIK, multi-layer capacitors are supposed to be soldered with their multilayered plates parallel with the PCB.Now, some MLCCs happens to have a square shape section (capacitor's height = capacitor's width), which makes them difficult to identify which are the up and down faces of the capacitor, and which are the lateral faces. For automated assembly, nobody cares about identifying which side should face the PCB, because usually the PnP machine will pick the capacitor straight from the reel.For manual assembly of capacitors with a square section, identifying the correct side that should face the PCB is not possible without a microscope.How bad would it be if a MLCC is soldered by mistake at 90 degrees (flipped 90 degrees along the capacitor's axis, not thumbstone flipped)?I couldn't find any assembly guidelines talking about "sideways" mounting. Anybody know any guidelines about this, please?

author: ovnr
author_rank: Frequent Contributor
timestamp: April 16, 2018, 05:18:14 pm
content: For any normal application: It doesn't really matter.As it happens, there's an app note out there (quick google didn't find it) showing that it does matter for RF applications, and that some RF caps are actually meant to be mounted with the plates vertical - and they're packaged in the tape that way.

author: RoGeorge
author_rank: Super Contributor
timestamp: April 16, 2018, 05:42:31 pm
content: I'll try to find that RF note, thank you.Does it happen for you to remember any app note or assembly guidelines where they consider the mechanical problems if the capacitor's internal layers are not parallel with the PCB, please?

author: helius
author_rank: Super Contributor
timestamp: April 16, 2018, 06:01:05 pm
content: I don't think the mechanical strength of the MLCC is affected by such a difference in positioning. The plates aren't the part that cracks, it's the bulk of the ceramic and it will happen the same way in both cases.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 16, 2018, 07:49:51 pm
content: Probably slightly more prone to shorting when fractured?That's about all I can think of.Tim

author: dmills
author_rank: Super Contributor
timestamp: April 20, 2018, 08:38:46 pm
content: IIRC there was a very short app note from Advanced Technical Ceramics,http://www.atceramics.com/Userfiles/vertical_orient.pdfI also remember something rather better from another of the RF speciality cap vendors?

author: ovnr
author_rank: Frequent Contributor
timestamp: April 20, 2018, 09:34:59 pm
content: Johanson has this app note:https://www.johansontechnology.com/downloads/technotes/JTI_SRF-PRF_9-01.pdfI recall something even more detailed, but can't find it. I did find a number of hits for RF caps that were pre-rotated (that is, ships with vertical plate orientation in the tape).

author: RoGeorge
author_rank: Super Contributor
timestamp: April 20, 2018, 10:05:08 pm
content: Interesting, thank you!

author: G0HZU
author_rank: Super Contributor
timestamp: April 20, 2018, 10:42:55 pm
content: I posted up some info on this subject a few years ago. The link below may be of some help? I made some measurements on some real caps in both horizontal and vertical.https://www.eevblog.com/forum/projects/coupling-capacitors-for-microwave-frequencies/