about capacitance of smd chips

[senz_90]

hello everyone. i have read about smd caps marking code, but i think there is no any number on smd chips that i have ever saw. i want to learn this because everything now using smd chips especially lcd mainboard.

just a dumb question, how do you know smd caps value ?til now i just see different size caps and the color is same at all likes chocolate? yes i try to see with magnifier but don't see any number or mark.

[mariushm]

Re: about capacitance of smd chips

You measure it with a multimeter, after desoldering one side, or both sides.

No markings on capacitors because it saves money, or there's not enough room to print the capacitance, tolerance, voltage rating on a 0402 or 0603 smd chip.

0805 is basically gone, 0603 is on its way out, 0402 is becoming the norm these days.

[senz_90]

Re: about capacitance of smd chips

You measure it with a multimeter, after desoldering one side, or both sides.

No markings on capacitors because it saves money, or there's not enough room to print the capacitance, tolerance, voltage rating on a 0402 or 0603 smd chip.
__
0805 is basically gone, 0603 is on its way out, 0402 is becoming the norm these days.

so i am need capacitance meter? okay, i see. thanks.

i read too we can compare the values with nearly caps that has same size and colour (if suspected one has shorted or open), because that is always nearly same value, is this true?

i dont know what number you means but the caps that i means is the ones likes smd resistor. likes a small grain. i have read it has A,B,C etc code or number, but as long as i try to see, nothing.

[vinceroger69]

Re: about capacitance of smd chips

so i am need capacitance meter? okay, i see. thanks.

i read too we can compare the values with nearly caps that has same size and colour (if suspected one has shorted or open), because that is always nearly same value, is this true?

i dont know what number you means but the caps that i means is the ones likes smd resistor. likes a small grain. i have read it has A,B,C etc code or number, but as long as i try to see, nothing.

i have always wanted to know this as well as to how to test them correctly and there values etc.

[mariushm]

Re: about capacitance of smd chips

0402, 0603, 0805 are all standard sizes for ceramic capacitors.

See this section on Wikipedia: http://en.wikipedia.org/wiki/Surface...ology#Packages

There are more standard sizes than those but those are the most popular.

so i am need capacitance meter? okay, i see. thanks.

Yes, you would need a multimeter with a capacitance measurement function, or a LCR meter. A proper LCR meter is more expensive but is more accurate than multimeters and also gives you the ability to measure ESR of capacitors and also inductors and resistors (L in the LCR is for inductors, R is for resistors)

i read too we can compare the values with nearly caps that has same size and colour (if suspected one has shorted or open), because that is always nearly same value, is this true?

That depends. Once you have enough experience, you can tell just by looking at a circuit what the purpose of some capacitors or resistors should be, and then you can determine if you can assume the capacitance value should be the same as other capacitors around.

There's no rule about it, so you really shouldn't just guess.

[senz_90]

Re: about capacitance of smd chips

yes. that's makes me interest how to correctly test it and thanks to mariushm explained .

wow. you explains it very well. i understand so clearly now. thanks a lot

[SeanB]

Re: about capacitance of smd chips

If you want to measure ceramic capacitors remember the same physical size capacitor which looks identical can be almost any value from 22uF to 100pF, they can pack a very wide range into a nominally identical looking part. You also have to know the supply voltage, and remember the sad truth that a ceramic capacitor value depends on the applied voltage, so a 22uF capacitor will be that at 0V ( really not ever going to be used at 0v ) and could be down to 100nF at 10V or any value.

You really do need a LCR meter to check the values, preferably one with SMT tweezer probes to get a good measurement and an accurate reading. As a plus you can test inductors, resistors and then do not need a dedicated ESR meter.

[tom66]

Re: about capacitance of smd chips

0805 isn't gone, I still regularly use 0805 and 1206 on my boards. You can only get large capacitances in bigger can sizes.

[mariushm]

Re: about capacitance of smd chips

You do, but just because you do doesn't mean they're not going away.

The size is starting to be used more and more for "specialized" resistors and capacitors, like current sensing, fuse type resistors etc and in general, capacitors in 0805 or 1206 are becoming more expensive and harder to get.

I'm not saying "going away" it in the sense of "banned, not available" but rather, almost not worth using and sourcing.

[tom66]

Re: about capacitance of smd chips

The moment you can get a 47uF 25V capacitor in 0603 let me know... but for now, you can't. And probably won't for at least 10 years to come. And try dissipating 1/2 watt in a 0603 resistor and see how long that lasts... Ceramics have poor capacity for their size (though they've greatly improved) so they are quite big for the required capacitance and voltage rating.

Maybe if by what you mean on the "average" board with minimal power components and just large BGAs with 0201 ceramics but I can't recall not having a buck converter on a board in the last 10 projects I did and it's really hard to get the caps you need for those in 0603, unless you're just dealing with low voltages.

Ceramic caps aren't marked because you can't mark them... the outer layer isn't permeable to ink. You could coat and print them but that's another manufacturing step which increases the cost. A penny more per capacitor would increase the cost of most of my boards by 10%...

[senz_90]

Re: about capacitance of smd chips

btw tom66. are you norcal on youtube video? he makes a good video about bonds tab and test ldo regulator, also troubleshooting voltage measurement on tv connector to determines where is the board failed.. i learn so much from his video

[tom66]

Re: about capacitance of smd chips

I am not Norcal. Norcal is from Northern California and has a very American accent. I am from the UK and have a boring British accent.

Here is my repair channel, not much uploaded but may help:
http://www.youtube.com/user/ubuntututorials

I do like Norcal's videos but he hasn't made any for a while. Guess he's busy.

[mariushm]

Re: about capacitance of smd chips

Somewhat off topic but... too bad you're making so useful videos but for people like me it's painful to watch due to so much shaking the camera around. Then the lightning is horrible most of the time.. the videos makes it look like you're afraid of lightbulbs.

[senz_90]

Re: about capacitance of smd chips

Yes. He didn't make any video again. His video and dave is a MUST for tv or monitor repairer as i think. Sorry to bother you off topic. Hehehe.

Hahaha that's normal for electronic freakin' likes many of us mariushm. Sometimes we are wake up lately and find out our thing didn't repair yet

Yes. Sorry to makes this off topic question.

Thanks for seanb, mariushm, tom66 explained. I learn many from this forum. I'm not repair thing for live, so for now, i don't have any lcr meter. Just an analog vom and diy esr meter, bluering tester. I have think to invest one digital meter that have capacitance meter, also a decent soldering station. Wish me pass final exam on this month and get a good job to buy this.

[tom66]

Re: about capacitance of smd chips

Hey if anyone wants to donate money for a professional eevblog-like setup for a TV repair each week, I'm open to donations.

*chirp* *chirp*

Anyone?

Oh.

I made £60 last year on youtube ads, but mostly from the non-TV repair ones. I think I can almost afford a half decent tripod to go with my camera. But otherwise I do these videos as guides not as professional productions, and it's likely to remain that way for a long time.

[SeanB]

Re: about capacitance of smd chips

More than me, I made about zero, nada, zilch..... I am busy watching the scammer videos though, have had a few calls this month from a local call centre, really want to find out the centre name and location so that I can complain to other companies that use them.

Senzo from "Microsoft Support" I want you out of a job!

[mariushm]

Re: about capacitance of smd chips

I've spent the equivalent of 10$ on a 500w floodlight from a local diy store:

Similar to this:

http://www.amazon.com/Cooper-Lightin...gen+floodlight

http://www.amazon.com/Cooper-Lightin...gen+floodlight

The bulbs are cheap, as low as 50 cents each and they last for a few hundred hours. Sure, there's more expensive bulbs, like 3 for 5$ which are colder white or have more life but who cares.

I tied it with some network cable to the bar that holds the curtains and I have a cheap 20 pounds tripod from Amazon uk .. this one, it works great:

http://www.amazon.co.uk/gp/product/B...?ie=UTF8&psc=1

But you don't have to buy one. You could just stack a bunch of books you have around the house and put the phone or whatever you have on it. Or a chair, if you work on the floor.

[tom66]

Re: about capacitance of smd chips

I use a Samsung compact camera (PL120) which does 720p and will be getting a smartphone capable of 1080p video soon, probably a Galaxy S2 or S3. Main problem is my room is really too small with all TVs in it to have that equipment set up. Tripod and lamp and I'd be tripping over it all. I've got too many ongoing projects. Once I clean up my room, getting rid of a few TVs, I might consider trying to make more professional videos. But something is better than nothing.

[senz_90]

Re: about capacitance of smd chips

But something is better than nothing.

true !!

[trebo]

Re: about capacitance of smd chips

keep up the good work tom