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SMT Ceramic capacitors??

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Juglenaut

New Member
What are these and are they used in SMT applications, say it is 1/2 inch by 1/2 inch that is huge.

High current decoupling hmmm can it handle that much.

I never seen anything like this guy is selling.

**broken link removed**

SMT converted to through hole, I wonder why.

I just noticed he or she or whoever is from SD I wonder where he get this stuff..
 

Optikon

New Member
Juglenaut said:
What are these and are they used in SMT applications, say it is 1/2 inch by 1/2 inch that is huge.

High current decoupling hmmm can it handle that much.

I never seen anything like this guy is selling.

**broken link removed**

SMT converted to through hole, I wonder why.

I just noticed he or she or whoever is from SD I wonder where he get this stuff..

This guy simply paralleled a few SMT caps and put leads on it.. I doubt the leads would stay attached when you tried to solder it anyhow..

Besides, he ruined his ultra-low inductance by putting the leads on there!
Thats one good reason to use the smt devices by themselves..

Plus he wants more than a fraction of a penny for the thing?
 

Juglenaut

New Member
I sent a question:

He said that is the way he got them, as over stock on a build going into high current fuel pump controllers, said something about stuff on avionics or whatever, but never point out companies.

I asked him to test the leads to see if they were high inductance material, he said he could not get the leads to separate from the cap with a normal soldering iron, and it appears that the leads aren't made of copper.

Now I know that all metals have a certain inductance level to them, but it seems to me that if these things were made right it could have a lower inductance overall.

I always thought you would need a opposite like ferite to induce voltage off and conductor if the cap is ceramic and the leads made of some metal that helps this would the inductance matter if it was set up this way??

So if these leads made a high inductance would I just be able to take them apart and mount them the way I want?? What if the spacing was required to disipate heat, what if the clearance from the pad is required hmmm I dunno I just never really seen anything like this before, look like a custom fab but a good one from the way he made it sound and all.
 

Optikon

New Member
Juglenaut said:
I sent a question:

He said that is the way he got them, as over stock on a build going into high current fuel pump controllers, said something about stuff on avionics or whatever, but never point out companies.

I asked him to test the leads to see if they were high inductance material, he said he could not get the leads to separate from the cap with a normal soldering iron, and it appears that the leads aren't made of copper.

Now I know that all metals have a certain inductance level to them, but it seems to me that if these things were made right it could have a lower inductance overall.

I always thought you would need a opposite like ferite to induce voltage off and conductor if the cap is ceramic and the leads made of some metal that helps this would the inductance matter if it was set up this way??

So if these leads made a high inductance would I just be able to take them apart and mount them the way I want?? What if the spacing was required to disipate heat, what if the clearance from the pad is required hmmm I dunno I just never really seen anything like this before, look like a custom fab but a good one from the way he made it sound and all.

The kind of metal the leads are made of is not the most determining factor in overall inductance. More importantly is the loop area formed when the "capacitor" is installed into mounting holes.

For lowest inducatance: Clip those leads right off the part (all the way where they make contact) and solder the part directly to th eboard on each of its sides (where the leads used to be).

Anything other than that and I assure you the inductance will be higher.

Also though, overall I doubt it is that much inductance.. prolly only a couple tens-hundred nH.
 

Ldi Edt

New Member
Hi all,

These capacitors are manufactured this particular way in order to minimize the probability of cracking when mounted to a substrate/board.

This practice is not uncommon for 100v ceramics used on the -48v bus found in most telecom systems.

In order achieve high densities in dc/dc power conversion, it is a common practice to replace bulky aluminums with their ceramic counterparts which have MUCH lower esr, and as a result, very high ripple current capabilities.

An 1812 size mlcc mounted on a pcb that may get flexed might very well fracture, causing silver palladium to migrate between the + and - plates.
This in turn will cause a low impedance. The end result is alot of smoke
and fire. This is a common failure mode.

I have had to do a redesign of a dc/dc module because of this problem (along with many others), and had to replace the mlcc caps with smt film caps.

Go to the ITW Paktron site for further information.

Sean
 
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