Capacitors for an oven display

[RukyCon]

Hello, i need some help finding some capacitors for an oven display.
The capacitors i need are...
68UF 35V 130C to 150C
And possibly some
470UF 35V 130C to 150C
I need high temperature capacitors do to the poor thermal insulation.
Thanks

[retiredcaps]

Re: Capacitors for an oven display

Use digikey's parametric search.

Vishay has 68uF 35V in 125C.

Panasonic has 470uF in 125C.

For 68uF 35V, try going up a bit in voltage to see if you can get 135C.

Rubycon RX series goes up to 130C for ballast.

http://thecapking.com/50rx3047.html

[RukyCon]

Re: Capacitors for an oven display

I can not find anything good for the 68uf 35v cap.

[redwire]

Re: Capacitors for an oven display

But the rest of the board will not take 130-150°C anyway. PVC wires melt- Bunn coffee makers use all teflon wire. MCU and semiconductors can't take that much heat too.

It's easier to put the PCB (or big caps) in a cool place or get some airflow.

I think only MLCC ceramic caps can take such heat. The wet ones like tantalum & electrolytic- heat is very hard on them.
They are a specialty, expensive cap http://www.kemet.com/Hi-Temp-Ceramic

[RukyCon]

Re: Capacitors for an oven display

But the rest of the board will not take 130-150°C anyway. PVC wires melt- Bunn coffee makers use all teflon wire. MCU and semiconductors can't take that much heat too.

It's easier to put the PCB (or big caps) in a cool place or get some airflow.

I think only MLCC ceramic caps can take such heat. The wet ones like tantalum & electrolytic- heat is very hard on them.
They are a specialty, expensive cap http://www.kemet.com/Hi-Temp-Ceramic

I'm not sure how to get the PCB into a cool environment or how to get some airflow on it.

And i'm not sure where to look for the high temperature ceramic capacitors.

[budm]

Re: Capacitors for an oven display

Digikey?

[redwire]

Re: Capacitors for an oven display

Digikey offers no 35V-50V high temp MLCC's above 10uF.
I did see 25V parts, biggest is 15uF X8L or 4.7uF 50V.

If the controller board is located near a vent, under the oven, it is cooler and you get some airflow. I just think high temp caps would not help much.
Surely it has a relay or SSR to switch the heating element. These parts can't take over 105°C because they generate their own heat, so I think they would have a short life.
Next is adding a cooling fan for the board, or a heat shield.

[CapLeaker]

Re: Capacitors for an oven display

Newark Canada (Element 14) has 35V 470uF @135C rated Panasonics TP series. The 68uf capacitor you may have to go to a 100uF, as I haven't seen it.

[RukyCon]

Re: Capacitors for an oven display

Digikey offers no 35V-50V high temp MLCC's above 10uF.
I did see 25V parts, biggest is 15uF X8L or 4.7uF 50V.

If the controller board is located near a vent, under the oven, it is cooler and you get some airflow. I just think high temp caps would not help much.
Surely it has a relay or SSR to switch the heating element. These parts can't take over 105°C because they generate their own heat, so I think they would have a short life.
Next is adding a cooling fan for the board, or a heat shield.

The controller board is located in the top of the oven...

And adding something like a fan dose not seem like it will keep the board cool [unless i do something crazy like cut a hole in the panel.]

Now how do i find a heat shield?

[cagiva4ever]

Re: Capacitors for an oven display

well, is it possible to re-locate the Capacitors faraway from the hot place ?

adding needed lenght of wiring between caps and pcb, instead of soldering them into PCB directly ?

that would give also many cooling solutions for them caps,w hen located freely...........

[RukyCon]

Re: Capacitors for an oven display

At this point i'm just going to get some 100uf caps to replace the 68uf one.

[RukyCon]

Re: Capacitors for an oven display

Should i get this EPCOS capacitor... [100uf 35v 150c 1000h]
https://www.digikey.com/scripts/DkSe...46830413829537

Or this rubycon capacitor... [100uf 35v 130c 2000h]
https://www.digikey.com/scripts/DkSe...46830413829537

[redwire]

Re: Capacitors for an oven display

I didn't know automotive electrolytics rated to 150°C exist, $0.75 100uF 35V.
For every 10°C cooler, you double the cap's lifetime.
So 1,000hrs@150°C and ~5,000hrs/130°C rated. The Epcos B41868W7107 one looks better.

I'm not sure what the oven looks like. But having the control board at the top of the oven is the worst place for it. My point is the rest of the electronics wiring/relays/semi's/connectors will have a hard time with such high temps.

[RukyCon]

Re: Capacitors for an oven display

Ok then i will go with the Epcos 150c cap.

[RukyCon]

Re: Capacitors for an oven display

I have the capacitors but i have not installed them yet.
May get to it on the weekend.