Ceramic capacitors for higher voltage switchers

Sounds trivial but 30mohms times 5A squared is .75W on a 1206 cap. You now
have made an LED. :)


Joerg could get a patent on that - a one time LED.

Joerg wrote:
Robert Baer wrote:
Joerg wrote:
Robert Baer wrote:
Tim Williams wrote:
"Joerg" <invalid_at_invalid.invalid> wrote in message
news:7vdlbmFeo1U1_at_mid.individual.net...
Anyone know what sort of ripple the FK22 series from TDK can
take, say a 0.47uF/250V? I need some ceramics as output caps of a
SEPIC that is variable up to almost 100V, with some gusto (>50
watts). Can't use electrolytics because of a harsh environment.

Well, take a guess at power dissipation and find the damping
factor (X7R is what, 1.5% or something?). If you're running hot,
low power is probably a good idea, like 1/8W or something. And
use lots of copper (ha, like you ever have the space).

http://www.tdk.co.jp/tefe02/e4942_fk.pdf

Stacked SMTs are great but boutiquish and expensive.

So stack them horizontally instead? :-)

Or if you're cramped for horizontal space, maybe you could make a
capacitor daughterboard so they're stacked horizontally, on a
vertical board...

Tim

Just solder the caps in so they are on edge (vertical); one may
be able to use 4 in parallel this way and use the same PCB board
space.


Can't do that, it must remain machine-solderable.

I bet pick-and-place can do it..by using a small dot of adhesive to
hold a cap that is placed, another dot nearby for nest cap, etc (all
dots could be placed first and then the caps).
Solder paste mask can be same as if one cap laid down in
conventional form.
"Never" say "never".


Sure, everything can somehow be done but once you deviate from
industry standard practice -> $$$.

Pick and place IS industry standard practice...

mook johnson wrote:
"legg" <legg_at_nospam.magma.ca> wrote in message
news:voc6p5d30rpuv259b2k888bvk1hcj370n0_at_4ax.com...

On Fri, 05 Mar 2010 16:18:52 -0800, Joerg <invalid_at_invalid.invalid
wrote:


Gents,

Anyone know what sort of ripple the FK22 series from TDK can take, say a
0.47uF/250V? I need some ceramics as output caps of a SEPIC that is
variable up to almost 100V, with some gusto (>50 watts). Can't use
electrolytics because of a harsh environment.

http://www.tdk.co.jp/tefe02/e4942_fk.pdf

Stacked SMTs are great but boutiquish and expensive. Anything

0.47uF/>100V in thru-hole seems outlandishly pricey.

You can get capacitor characteristics from TDK.

http://www.tdk.co.jp/ccv/index.asp

The resistance, reactance and voltage/temperature dependencies are
illustrated graphically.

A 0.1uF 100V X7R part in 1206/3216 body size, 3216X7R2A104M, exhibits
an internal series resistance of 30mOhms, over the range of common
power conversion frequencies.

RL


Sounds trivial but 30mohms times 5A squared is .75W on a 1206 cap. You now
have made an LED. :)


Joerg could get a patent on that - a one time LED.

Robert Baer wrote:
Joerg wrote:
Robert Baer wrote:
Joerg wrote:
Robert Baer wrote:
Tim Williams wrote:
"Joerg" <invalid_at_invalid.invalid> wrote in message
news:7vdlbmFeo1U1_at_mid.individual.net...
Anyone know what sort of ripple the FK22 series from TDK can
take, say a 0.47uF/250V? I need some ceramics as output caps of
a SEPIC that is variable up to almost 100V, with some gusto (>50
watts). Can't use electrolytics because of a harsh environment.

Well, take a guess at power dissipation and find the damping
factor (X7R is what, 1.5% or something?). If you're running hot,
low power is probably a good idea, like 1/8W or something. And
use lots of copper (ha, like you ever have the space).

http://www.tdk.co.jp/tefe02/e4942_fk.pdf

Stacked SMTs are great but boutiquish and expensive.

So stack them horizontally instead? :-)

Or if you're cramped for horizontal space, maybe you could make a
capacitor daughterboard so they're stacked horizontally, on a
vertical board...

Tim

Just solder the caps in so they are on edge (vertical); one may
be able to use 4 in parallel this way and use the same PCB board
space.


Can't do that, it must remain machine-solderable.

I bet pick-and-place can do it..by using a small dot of adhesive
to hold a cap that is placed, another dot nearby for nest cap, etc
(all dots could be placed first and then the caps).
Solder paste mask can be same as if one cap laid down in
conventional form.
"Never" say "never".


Sure, everything can somehow be done but once you deviate from
industry standard practice -> $$$.

Pick and place IS industry standard practice...


But pick and place on edge isn't.

Define "edge"; methinks a 3D rectangle has 6 edges..

Pick and place IS industry standard practice...

But pick and place on edge isn't.

Define "edge"; methinks a 3D rectangle has 6 edges..

"Robert Baer" <robertbaer_at_localnet.com> wrote in message
news:2Z-dnWLtypQ5kwvWnZ2dnUVZ_gudnZ2d_at_posted.localnet...
Pick and place IS industry standard practice...
But pick and place on edge isn't.

Define "edge"; methinks a 3D rectangle has 6 edges..

Twelve. But you meant faces. ;-)

And you also know he meant the narrowest face (the face with one dimension
the longest and the other the smallest possible length across the rectangle,
out of the three dimensions which define the rectangular prism).

Joerg wrote:
Robert Baer wrote:
Joerg wrote:
Robert Baer wrote:
Joerg wrote:
Robert Baer wrote:
Tim Williams wrote:
"Joerg" <invalid_at_invalid.invalid> wrote in message
news:7vdlbmFeo1U1_at_mid.individual.net...
Anyone know what sort of ripple the FK22 series from TDK can
take, say a 0.47uF/250V? I need some ceramics as output caps of
a SEPIC that is variable up to almost 100V, with some gusto (>50
watts). Can't use electrolytics because of a harsh environment.

Well, take a guess at power dissipation and find the damping
factor (X7R is what, 1.5% or something?). If you're running hot,
low power is probably a good idea, like 1/8W or something. And
use lots of copper (ha, like you ever have the space).

http://www.tdk.co.jp/tefe02/e4942_fk.pdf

Stacked SMTs are great but boutiquish and expensive.

So stack them horizontally instead? :-)

Or if you're cramped for horizontal space, maybe you could make a
capacitor daughterboard so they're stacked horizontally, on a
vertical board...

Tim

Just solder the caps in so they are on edge (vertical); one may
be able to use 4 in parallel this way and use the same PCB board
space.


Can't do that, it must remain machine-solderable.

I bet pick-and-place can do it..by using a small dot of adhesive
to hold a cap that is placed, another dot nearby for nest cap, etc
(all dots could be placed first and then the caps).
Solder paste mask can be same as if one cap laid down in
conventional form.
"Never" say "never".


Sure, everything can somehow be done but once you deviate from
industry standard practice -> $$$.

Pick and place IS industry standard practice...


But pick and place on edge isn't.

Define "edge"; methinks a 3D rectangle has 6 edges..

Michael A. Terrell wrote:
Joerg wrote:
That's one reason why I asked. I've managed to turn capacitor ceramic
into bubbly green glass. But that was several MHz and several amps
through just one. The usual, had only one, did a quick experiment, "Come
on, hang on another 10 secs" ... *PHOOMP*


You have been reported to the 'Society For The Prevention Of Cruelty
To Components'.


Now, wait! Have you seen John Larkin's collection of mutilated TO220
MOSFETs? So if there is a tribunal he should have to go first ...

Joerg wrote:
Michael A. Terrell wrote:
Joerg wrote:
That's one reason why I asked. I've managed to turn capacitor ceramic
into bubbly green glass. But that was several MHz and several amps
through just one. The usual, had only one, did a quick experiment, "Come
on, hang on another 10 secs" ... *PHOOMP*

You have been reported to the 'Society For The Prevention Of Cruelty
To Components'.

Now, wait! Have you seen John Larkin's collection of mutilated TO220
MOSFETs? So if there is a tribunal he should have to go first ...


Squealing on your coconspirators won't get you a lighter sentence!

Michael A. Terrell wrote:
Joerg wrote:
Michael A. Terrell wrote:
Joerg wrote:
That's one reason why I asked. I've managed to turn capacitor ceramic
into bubbly green glass. But that was several MHz and several amps
through just one. The usual, had only one, did a quick experiment, "Come
on, hang on another 10 secs" ... *PHOOMP*

You have been reported to the 'Society For The Prevention Of Cruelty
To Components'.

Now, wait! Have you seen John Larkin's collection of mutilated TO220
MOSFETs? So if there is a tribunal he should have to go first ...


Squealing on your coconspirators won't get you a lighter sentence!


What? No plea deals?