freeing SLCC disk capacitors

[coppercone2]

I want to get the ceramic? coating off ceramic disk capacitors (SLCC, the ones that look like a oreo). Usually their like 500V and some where in the pF to nF range

It kinda chips off. Its hard to get in there. A few times I have seen it crack off for no reason.

Is there a easy way, that does not involve grinding it?



like this thing
https://ph.element14.com/multicomp-pro/mcbu5102k5/cap-1000pf-50v-10-y5p/dp/9411780


There is also the epoxy type, which might be a better choice, but I have a bunch of ones that feel like terra cotta. I think getting into the epoxy ones might be easy, but how about this other type?

[bairdbankovic]

Why do you want to get the ceramic off? Are you just curious to remove it - or is there some application that needs it removed?

As far as removing ceramic, that would be quite difficult. You can likely dissolve the ceramic in hydrofloric acid (HF), but that will also eat the capacitor. Also HF is really really really nasty stuff, but if you have access you could try that.

If you get the epoxy ones, you can use a hot air gun set to a very high temperature to breakdown the epoxy. Then, you can use some small pliers to break away degraded epoxy.

[coppercone2]

It would result in a metalized high K dielectric substrate. This can probobly be etched or extra plated and etched by using a photo mask. With a high resolution mask its maybe possible to do something with the substrate involving ceramic antennas.


However I do wonder how much of a difference it makes to metalize it, it almost seems you can wrap the damn thing in magnet wire and it should work, perhaps wire that has been carefully flattened with a hammer

[TimFox]

The Hi-K dielectric is likely to have lousy dielectric loss at high frequencies.

[coppercone2]

I don't know, I read some SLCC caps are good to many GHz, I don't know how a Y5V will do, but its certainly not too hard so long you can get it exposed.


Pitty I had one that was near a exploded MOV and the ceramic split off following the thermal explosion from the vaporized MOV! years ago


https://www.cirocomm.com/en-global

[TimFox]

SLCC and MLCC are construction methods, and can be made from Class I or Class II (high-K) dielectrics.
NP0/C0G Class I dielectrics usually have Q > 1000.
Y5V Class II dielectrics (very high K) have Q around 10.

[coppercone2]

I don't know, I read that the ceramic antennas use a high K dielectric some where.


I suppose its possible they mean that its a high k dielectric at microwave frequencies which are not high K dielectrics in capacitor standard sales nomenclature. but fortunately SLCC capacitors of C0G or whatever exist too. I don't know of any tables that show the parameters let alone mystery capacitor compositions, but it seems like a easy experiment to do.

As I understand the class of capacitor is by no means any indicator of composition, because it is purely based on a temp spec, with whatever materials they can find cheaply that work.

[TimFox]

There is a direct correlation between the specific capacitor dielectric type (C0G, X7R, Z5U, etc.) and its dielectric loss (Q) as well as its temperature co-efficient.
Ceramics are also used in waveguides, for example, but they do not have the extremely high dielectric constant (and therefore optical index) as the high-K dielectrics used to make small high-capacitance capacitors.

[coppercone2]

This is a random example

https://www.ripublication.com/irph/ijict_spl/ijictv4n13spl_03.pdf

In this one it looks different then the coil or stripline versions I saw before. I don't have notes for this topic.

Example of something that might be etched, here is a spiral antenna, possibly served on capacitor

https://www.nature.com/articles/s41598-018-35480-7


Here high K material is mentioned, but I don't have the article
https://ieeexplore.ieee.org/document/7346299



https://www.cirocomm.com/en-global/tech_pro/index

Ceramic Processing Techniques
Our main factory is located in Tainan City, Taiwan with 5000 SQM floor plan. Cirocomm is one of the ceramic frequency part makers, capable of processing from ceramic powder raw materials to final DR filters and antennas for RF application. We shrink the filter and antenna size by use of ceramic and high K value materials.

I think maybe its possible. I think I can even feed disk capacitors into a laminator somehow. There are a few options for disk capacitors. Reasonably it looks like you can get at least three different disk capacitor types pretty easily, for SLCC.


For dry film, I have some that supposedly has very high etching resolution too, generally the one that is most popular does not have ultra fine resolution (its not needed, the lower resolutions are more reliable/tough/easier to use).

[TimFox]

The dielectric constant quoted in the first paper is on the order of 50 to 70.
It uses GaAs over SiO₂, which is not a typical material for SLCC capacitors.
The article has a table of dielectrics that range from 12 to 94.
I can't find the dielectric constant of Y5V material quickly.

[coppercone2]

It's possibly something to do with different interpretations of high K between filter capacitor manufacturers and RF people.


Anyway, even if Y5U substrates can't do antennas, it might have another application being lossy. Not sure what it is, but I am still curious to try to etch one of those suckers to see what happens. I gave antennas because its the only application I am familiar with, but there must be more, I am interested in the process more then end result.

This might be better suited for an antenna
https://twen.rs-online.com/web/p/single-layer-ceramic-capacitors/8312932

But I would still experiment with cheap ass ones for getting the process down, I think it will etch similar and its basically garbage.


The 270pF C0G is about 0.9 inches! wide, thats a pretty big sample

[TimFox]

How high is high?  The answer differs depending on application.
I recommend against Y5V and similar dielectrics for your application, since they are ferroelectric, non-linear, and lossy.
Perhaps C0G or similar would work for you.
I believe the coatings on disc ceramic SLCC are an epoxy or similar, rather than ceramic.
The Ceramite datasheet shows epoxy or phenolic coating in their process list.

[coppercone2]

yeah it looks like its not worth trying to save a few dollars at this point


unless there is some good use for lossy nonlinear dielectric at high frequencies


the y one is so god damn cheap. 33 cents store. I better take advice from simpsons and avoid them lol. gagged thinking about it