SMD capacitors

I'm not sure I understand your question. Whether a cap is polarized or not depends on the type cap. Tant's and Al are polarized (in general) and ceramics aren't.

George H.

If they are MLCC, the capacity can be quite high maybe even 10uF these days, but very low V and a susceptibility to metal migration it PbF soldering temp requirement fracture the ceramic at laying

I have read about the need to slowly heat the capacitors to keep them from fracturing. I doubt I will use any of the lead free solder, being in the US and this is just a hobby for me. I have a spool of some .25 and .15 solder that is 63/37 so should be good for life with that.

The listing does not say what kind of capacitors they are, just the size and SMD capacitors.

The 2.2 uF is rated for 25 V and the 10 uF is rated for 10 V,, most of the others are for 25 or 50 V which is more than most circuits I will be dealing with.

They probably come out of China and may not be very good quality, but for the price and my hobby usage I thought it may be a way to have a stock on hand. I try to keep many small parts on hand if they are not too expensive. Never can tell when I may want one and don't want to wait on the mail from Digikey or Mouser, evenif it is only a few days. Wouldn't surprise me if many of the electronic items don't come from over seas. Some very good,, some not so good.

I remeber around 1970 while in school we took a tour of a TV studio and they were telling us how the Japan cameras were better than any other at that time. That was still back when many people thought anything comming out of Japan was no good. Maybe some of the China items will be the same way.

That may be the key. The listing did not say what kind of capacitors they are, just SMD and the value and voltage rating. Whatever they are, they are probably the same material, so the larger ones won't be ploarized either. I did notice the voltage on them is only 10 volts instead of 25 and 50 like the others.

Last I looked the planet's number 1 supercomputer is or was Chinese. Tianhe-2 iirc.

NT

X7E caps are not recommended.

The lower voltage ratings are probably tantalum, polarity is *VERY* important.

Don't be fooled by large capacitance values - I've seen a brochure for MLCC capacitors up to 180uF.

SMD tantalum caps are usually encapsulated (after a fashion) and usually have markings.

SMD ceramics are rarely encapsulated and rarely have any markings. Sometimes I've encountered MELF round glass encapsulated MLCC caps on high end equipment.

Yes, the polarity is very important if the capacitor has one. I have not installed any of thse backwards to see what happens as of yet. I have seen the old aluminum and tantalum one blow over the years.

I am not used to seeing capacitors ( other than large AC and speaker crossover) much over 1 uF.

I can see why they don't mark most of the SMD, just no room but with micro printing there may be a way but it would cost. Even buying them from Digikey and Mouser they are very inexpensive compaired to the old point to point components.

As mentioned, been working with components for over 50 years,but just started with the SMD in the last year. Could not justify the items it took to do that for just a hobby. Now they have came down a lot. Like the China hot air rework station for about $ 60 and a $ 200 microscope. The hot air station is probably no where near good enough for regular shop work,but good enough for hobby,and if it breaks, the replacement is not that much.

I am learning a lot about the capacitors with the help here.

I've seen SMDs where one end is a bit pointed to indicate polarity.

If there's really nothing to indicate polarity it's most likely nonpolar. Hook one up & see, not that hard.

NT

Ralph Mowery wrote on 8/29/2017 5:55 PM:

I think you just answered your question. If the caps have polarity markings they are polarized. If they don't have polarity markings, how do you know you have any installed correctly?

MLCCs (which are ceramic) can be found above 1 uF. I often use them at 10 uF and I know they are available at higher values. The product of capacitance and voltage determines the size, so in a given size the voltage will drop as the capacitance approaches the max value. There are also different material ceramic caps with widely different tolerances and voltage/temperature responses. X5R is a good general purpose type of ceramic cap.

While the idea of a cap is pretty simple, the realities can get pretty complex.

--

Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Someone sent a pix with several kinds of the SMD capacitors. A couple of them had a pointed tit on one end. I did not know that,so would have missed that as a polariaty mark. If I had just looked at the capacitor, I probably would have dismissed it as just a blob of material instead of a polarity mark.

Sometimes it helps to know all the small details of the components. I don't know, but guess that some could not have any marking and it could depend on how they are placed in the reel they come in.

I don't know if that *is* a polarity mark. I'm not sure what you are describing, but I don't recall seeing any SMD polarized capacitors that don't have *clear* markings of polarity. Do you have an image or can you find a similar cap on the Internet?

I've never seen polarized caps that weren't marked. I've never seen polarized caps that relied solely on the reel orientation to indicate polarity.

--

Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Here is a link to a px of some SMD capacitors. The two on the right have that little tit I mentioned. It could be mistaken by someone like me that has never seen one as just some excess solder when it was made.

There probably are not any that are not marked in some way. I was just guessing at the reel thing.

As mentioned it is a hobby now and upto a short while ago I had not messed with any of the SMD. There have been lots of advances and changes in the components over the years. Just more to learn. I still have trouble with the values of some components being packaged in a small package.

Just hope I am not sounding like some of the other older people on here with the SMDs.

Ok, these are un-encapsulated tantalum caps and that pin is a part of the device internal connections. They are the same part as the yellow ones to the left (and maybe the black ones too, but not the round ones which are electrolytic), but without the plastic coating to make them smaller. Yes, the point might look like excess solder, but if you use a part without looking at the data sheet you are screwing up.

Trouble? You mean you have trouble accepting the small sizes?

Only a little... ;) Wanting to learn new stuff is what is setting you apart. It is hard to go with new ideas when you've been doing the same thing for a long time, especially when the eyesight makes it hard. But it's not impossible. I have essential tremor but I still make stuff from time to time. When it's work I let an assembly house deal with it.

--

Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998

Not really trouble, but just have not worked with the SMD enough to learn all the small details. Like learning that they can make a capacitor of over 1 uF the size of fly poop and not big enough to have any markings on them.

The first computers I dealt with had the memory chips that would thake 8 chips to make about 1 K of memory, maybe not even that much. Just the memory board alone for 8 K of memory was larger than several of the smart phones now. Now they over 100 GB of memory in the space of one of those chips. I can accept them, just have not seen enough of them to know they are in use.

I just have to keep up with the times. Like the cars. I remember changing oil from 30 W to 20 W and back when the temperature changed from summer to winter, and change every 3000 miles, or was it less. Then came the 10W 40 types and no change was needed for summer to winter and 5000 or 7500 mile change.. Just bought a new car and the recommendation is 0 w 20 and only change at 10 K miles. They give 2 years free maintence. Going by the book, that is only 2 oil changes the way I drive. Nothing else to be done but look it over.

I don't mean to go further on a tangent and I have no experience with the A

+++ related computer hardware construction and repair, but I know fans keep computer hardware cool. But with cold capacitor heat rising to fast, shoul d something like incandescent light bulb first turn-on before cooling fans kick-in in a CPU tower-area to keep hardware temperature more at an exact s etting?

e

A+++ related computer hardware construction and repair, but I know fans ke ep computer hardware cool. But with cold capacitor heat rising to fast, sho uld something like incandescent light bulb first turn-on before cooling fan s kick-in in a CPU tower-area to keep hardware temperature more at an exact setting?

can you put that in english?