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Double sided MCPCB with plated through vias is possible?

Flyback

Well-Known Member
Hi

We wish to make a 6W Buckboost switch mode lighting PCB (15cm by 1.8cm) with LEDs one side and the driver electronics the other side. (everything SMD) There will also be a microcontroller to give dimming control.

We want the PCB to be as thin as possible, but not so thin it bends easily.

We believe that we can have two pieces of MCPCB which sandwich a plastic core. We will need plated through vias for the tracking of the driver & control electronics. We believe that plated through vias can be achieved with this setup, and can be done by simply drilling though both pieces of MCPCB where the vias occur, and then drilling through the plastic core in the same position…then plating the hole of the plastic core.

Do you believe that this is possible?

How expensive would you think this would be?

Vin = 20 – 50V
V(LEDs) = 45V
 

dknguyen

Well-Known Member
Most Helpful Member
What you described wouldn't work anyways since it doesn't solve the problem of the sides of the all via holes being electrically connected to the entire metal core. Plating as you described just causes the plating to sit on top of the edges of the exposed metal core in the via hole and connects the metal core(s) to the signal on both sides of the PCB.

That notwithstanding, yes, you can have plated vias on a two-sided metal core PCB What they do is use a two-sided board with one metal core, but drill an oversized via hole and seal it with an insulator before plating it.

https://www.multi-circuit-boards.eu/en/pcb-design-aid/layer-buildup/metal-core-pcb.html

You'd have to ask the board fab for cost.
 
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Flyback

Well-Known Member
Thanks, i suppose the via holes would have a minimum size as otherwise the drill would snap if too thin? I suppose vias >1mm would be the situation there?
 

dknguyen

Well-Known Member
Most Helpful Member
You have to ask them for details about their fab process but 1mm is a friggin enormous via hole by their standards. 0.3mm is the standard minimum but fabs do have tooling for smaller holes. It's not standard though so will cost extra. I think really tiny small holes use a laser but even with a mechanical drill, you can drill vanishingly tiny holes as long as a machine is feeding and guiding the drill. With such tooling, PCB thickness limits hole diameter before the tooling does.
 
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gophert

Well-Known Member
Most Helpful Member
Hi

We wish to make a 6W Buckboost switch mode lighting PCB (15cm by 1.8cm) with LEDs one side and the driver electronics the other side. (everything SMD) There will also be a microcontroller to give dimming control.

We want the PCB to be as thin as possible, but not so thin it bends easily.

We believe that we can have two pieces of MCPCB which sandwich a plastic core. We will need plated through vias for the tracking of the driver & control electronics. We believe that plated through vias can be achieved with this setup, and can be done by simply drilling though both pieces of MCPCB where the vias occur, and then drilling through the plastic core in the same position…then plating the hole of the plastic core.

Do you believe that this is possible?

How expensive would you think this would be?

Vin = 20 – 50V
V(LEDs) = 45V
What is the goal? Heat dissipation? How many watts of LED power per square inch on LED side? How many watts of power loss (SMPS losses) on the other side?
What are your heat sink specs?
 

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