0603 Ceramic Capacitors and Soldering Damage during Repair - Page 1
Forum section: electronics / repair

author: mikkkejickles
author_rank: Contributor
timestamp: October 29, 2018, 07:11:26 pm
content: Hey Folks,As I was soldering some (good quality) ceramic 0603 capacitors from mouser, a couple ended up sticking to the iron for 4 or 5 seconds @ 350 degrees Celsius. After this they look darker than the others (obviously).My question is if those capacitors are actually destroyed?Sorry if this is a stupid question. This was my bad technique at the time.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 29, 2018, 07:32:52 pm
content: Not in my experience.if you're suspicious, do an electrical test when you're done: verify that the capacitors are the correct value and not shorted. This may not be possible for all capacitors in a finished circuit, or maybe you can test as you go, I don't know.Hmm, I wonder if the flex-contact type capacitors degrade with heat. AFAIK, they use an epoxy undercoat, which would be prone to decomposition at that temperature. (If the parts you bought don't specify flex type, then they're not flex, just plain old solid ceramic and metal.)Tim

author: KaneTW
author_rank: Frequent Contributor
timestamp: October 29, 2018, 07:47:02 pm
content: I recommend readinghttps://nepp.nasa.gov/files/16346/08_002_01%20GSFC%20Teverovsky.pdf--- cracks are relatively easy to cause, and while they don't impact capacitance too much, they cause an increase in avalanche breakdown failures and leakage current.

author: DC1MC
author_rank: Super Contributor
timestamp: October 29, 2018, 07:58:12 pm
content: Quote from: mikkkejickles on October 29, 2018, 07:11:26 pmIf the 350 degrees are really Celsius, then they are gone now, what kind of solder do you use for 350C ? If there are 350F then they degraded a bit but survived most likely.Cheers,DC1MC

author: langwadt
author_rank: Super Contributor
timestamp: October 29, 2018, 08:02:01 pm
content: Quote from: DC1MC on October 29, 2018, 07:58:12 pm

author: DC1MC
author_rank: Super Contributor
timestamp: October 29, 2018, 08:08:57 pm
content: Quote from: langwadt on October 29, 2018, 08:02:01 pmHääää ?

author: Howardlong
author_rank: Super Contributor
timestamp: October 29, 2018, 08:14:04 pm
content: There can be problems with ceramic caps due to the the package cracking with repeated or uneven temperature cycling. The cracks are frequently not visible under inspection. This can lead to intermittent problems which become worse over time due to small mechanical stresses, for example board stress when cycling connectors.I learned this the hard way, but in general if you need to rework with an iron rather than reflow, consider replacing the caps that you thermally cycle.Edit: the darkening might just be dead flux, so consider cleaning your board.

author: tooki
author_rank: Super Contributor
timestamp: October 29, 2018, 11:37:15 pm
content: Quote from: langwadt on October 29, 2018, 08:02:01 pmSay what now?!?I use 290-310 for leaded solder and 300-350 for lead-free — for through-hole! For small SMD parts like an 0603 I could probably get away with even less. (The only time I've had to really crank up the heat on SMD was to replace a quite large (~12mm square) ferrite choke.)

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 30, 2018, 06:08:34 am
content: You are either a much more patient person than most of us... or you're using a beefy JBC.(Or your iron's cal is off)Tim

author: KaneTW
author_rank: Frequent Contributor
timestamp: October 30, 2018, 06:42:15 am
content: I usually solder leadless SMD at 350C. Should be able to lower it quite a bit if I had a preheater, but alas.

author: tooki
author_rank: Super Contributor
timestamp: October 30, 2018, 11:42:39 am
content: Quote from: T3sl4co1l on October 30, 2018, 06:08:34 amIt's an Ersa i-Con nano. Probably not out of cal given how new it is — but it is a powerful iron that can heat fast.

author: amyk
author_rank: Super Contributor
timestamp: October 30, 2018, 12:12:50 pm
content: You can test them if you want to be sure but I doubt they'll be much affected --- the normal manufacturing process of those capacitors involves baking them at much higher temperatures --- they areceramicafter all...https://en.wikipedia.org/wiki/File:MLCC-Manufacturing-Process.png

author: Howardlong
author_rank: Super Contributor
timestamp: October 30, 2018, 05:01:30 pm
content: Quote from: amyk on October 30, 2018, 12:12:50 pmUnder reflow, yes, but if you’re hand soldering with an iron, there is much more thermal stress as the package is unevenly heated, see my comment above.

author: mikkkejickles
author_rank: Contributor
timestamp: October 31, 2018, 04:33:41 am
content: Really appreciate all the replies folks. I'll test them at the end! There are 64 of them.They're automotive capacitors but I'm using them for a video up-scaling device.Here is the datasheet.https://www.mouser.com/ProductDetail/81-GCM188R71C104KA7J