Question about high voltage PCB design

"Ge0rge Marutz"

** Surely it is easier to spread 100 or so low wattage resistors over a PCB that your idea ?

A simple series parallel array would have no issues with 400 volts DC.

OTOH - using a SINGLE, whisker fine track that snakes for 50 metres or more is begging for troubles.

........ Phil

50 meters is rather excessive. I need 11 meters.

"OTOH - using a SINGLE, whisker fine track that snakes for 50 metres or more is begging for troubles."

Can you elaborate on this statement?

Thanks,

Ge0rge

** Surely it is easier to spread 100 or so low wattage resistors over a PCB that your idea ?

A simple series parallel array would have no issues with 400 volts DC.

OTOH - using a SINGLE, whisker fine track that snakes for 50 metres or more is begging for troubles.

** Just how many watts of heat are you generating here ?? 11 metres of the finest copper track is not a very high resistance. ** If it breaks at one tiny spot = no heater.

........ Phil

Trace width can be kept wide enough to where it will not be that fragile. Just about any board house can reliably manufacture a 1mm wide trace on 1/2 ounce copper.

I intend on building up a few and put them on long term durability test to check feasibility. I already have a 20V, 500W version on test. It has 1300 hours on it so far with no signs of degridation.

My primary concern is with the higher voltage. I typically don't work with stuff above 20V.

Ge0rge

** Please click on "options" and then "reply" so your posts show some context and name of the other party when they appear on usenet.

** 11 metres of 1mm wide track is only 10 ohms or so.

Are you for real ??

** That is less than 1 ohm.

At 400 volts you need * 320 ohms * for 500 watts.

Now read my earlier posts again.

....... Phil

Your primary concern should be learning what usenet is and how to post on it, followed by learning ohms law.

--

One problem I see with this approach is that it doesn't take much heat to get the copper to delaminate from the FR4.

And possibly release some harmful fumes in the process.

Regards, Joerg

Yeah, well, I've had a bad feeling about it from the start, but I've "held my tongue" because I don't have the right background; but I'd think there'd be a way to embed a serpentine piece of nichrome wire in some kind of mat that would accomplish the same thing.

Good Luck! Rich

On 11 May 2006 07:25:16 -0700, "Ge0rge Marutz" Gave us:

Tell us again what part of "20 volts" is high voltage?

On Sat, 13 May 2006 00:53:22 GMT, Rich Grise Gave us:

One is NOT going to dissipate 500 Watts in ANY transducer, whether it is a piece of trace, wire or other device, and not have a burned PCB substrate... Every time.

The guy did not give enough info about what his goals are. Not in the PCB design, but WHAT is the application at hand?

Using a PCB as a heater device mount is not very bright... at all.

What is the job? That IS the question.

"Roy L. Fuchs"

** Geezus - what an asinine moron.

Fuck off - Fuchhead

......... Phil

George,

There are (at least) a couple of basic problems in what you're proposing:

If you'd like to use a conducting trace (i.e. low resistance) as the heater, for practical reasons that means a low voltage & high current design ... the 400V spec is really not compatible with this.

There was mention of solder flux in your 1st post, so I'll also just mention that solder is not how heater elements should be connected, if that is your intention.

Mark

On Sat, 13 May 2006 15:22:53 +1000, "Phil Allison" Gave us:

You're a goddamned retard, Allison.

"Roy L. Fuchwit-Asshole

** Geezus - what an asinine moron.

Fuck off - Fuchhead

On Mon, 15 May 2006 11:51:55 +1000, "Phil Allison" Gave us:

Fuck off, Philtard...

I would also wonder about the tolerance of the resistance. Board probably has a minimume conductivity specified, but not a maximum one. That said the copper won't be too thick I suppose.

Something similar applies to trace width.

Thomas