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Curious PCB technology

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#84264

Curious PCB technology | 23 January, 2020

Hello,

There is curious PCB technology used for one aluminum LED PCB.

First of all there is no solder mask. PCB tracks look grainy and there is no fillet near components. Tracks near components are thicker.

A kind of material has been applied to aluminum substrate and has been processed by technology I have never met before.

What might it be? 3D printing? A sort of special masking and developing process?

This PCB must be low cost one I suppose.

Any input would be really appreciated.

Regards, Pavel

Attachments:

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#84273

Curious PCB technology | 24 January, 2020

The joint material looks like some kind of conductive glue. However, I can't tel from the picture what is this solder mask?

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#84274

Curious PCB technology | 24 January, 2020

Evtimov,

There is no solder mask at all. Material is applied over bare aluminum.

Regards

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DWL

#84275

Curious PCB technology | 24 January, 2020

what does the PCB go into?

Is it for use in an extreme environment?

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#84276

Curious PCB technology | 25 January, 2020

DWL,

This is general purpose outdoor lighting product, a digit used at petrol filling stations for displaying prices.

Nevertheless, this is IPC class III product.

Regards, Pavel

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#84281

Curious PCB technology | 27 January, 2020

Looks like a screen printed circuit using a platinum or palladium silver paste. This would account for the grainy appearance. I 've seen this on a white ceramic substrate but not on aluminum. Any components are attached using a silver conductive epoxy.

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#84285

Curious PCB technology | 27 January, 2020

That's a pretty pricey process, no? Wonder why someone would use these materials to build a PCB like this?

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#84287

Curious PCB technology | 27 January, 2020

Solvent resistance? That's the only thing that made any sense to me.

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#84288

Curious PCB technology | 27 January, 2020

I have to ask this because "Material is applied over bare aluminum" doesn't make sense to me.

Is that some kind of electrically insulative black anodization on the board surface? Because if it's just bare aluminum, how is the entire circuit not shorted?

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#84289

Curious PCB technology | 28 January, 2020

Steve,

I am sorry for misinforming. Indeed, there is a sort of insulator over aluminum that looks like powder paint. No hesitation the circuit would be completely shorted otherwise.

Regards, Pavel

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#84326

Curious PCB technology | 29 January, 2020

Pavel, no worries. I assumed as much but wanted to make sure I wasn't completely missing something in the description!

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#84337

Curious PCB technology | 30 January, 2020

Even if it is no where near the pumps it is probably certified explosion proof.

Could they have had aluminum sheets, painted them, cured them, stenciled conductive traces, cured it, stenciled conductive adhesive, populated parts, cured it then singulated?

And I would say that it does have masking, under the traces.

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#84339

Curious PCB technology | 30 January, 2020

Clever idea. I used to work on hybrids. baking temp about 850 degrees C we used titanium and ceramic substrates. the high temp was needed to make the resistance layer partially melt. remove the resitance and you can run at the silver melting point and then do component placement and solder reflow at 230 degrees. Next step through away the silver and do cold copper depostion for your tracks that would be better still. Silver as a conducting layer has it's issues in repair.

sarason

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#84458

Curious PCB technology | 14 February, 2020

Sorry, I'm confused. I just purchased PCB from cplfpc.com only once and from there only I got to know something about it. Could you please elaborate clearly?

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