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I would like to fabricate a slight enhancement over the metal-core PCB's shown here:

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=6071

Specifically, my application requires 2 LED's of different wavelengths that can be toggled using a switch or MOSFET.

In principle, the PCB would be a very simple single-layer design which I could mill out from a copper-clad blank -- that is, if it were FRA-core.

However, I'm not sure how to proceed with creating a DIY metal-core PCB. Is it possible? Is there an equivalent "blank" that can be purchased? Are there any tutorials or best-practices published online?

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  • \$\begingroup\$ What about using a steel sheet and some glue? \$\endgroup\$ – Marko Buršič Jun 2 '17 at 8:53
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One of the best tutorials I find is Google Images. That leads to:-

pcb

and aluminium PCB manufacturers

At first glance, it looks fairly simple for DIY, especially since you're making a one sided board. The insulating layer automatically becomes the fibreglass or epoxy paper part of the stock PCB. Your dielectric won't be as thin as my image though and this will seriously compromise your thermal conductivity. 150 um is ~1/10th of the thickness of a 1.6mm PCB, and so thermal conductivity will also be ~1/10th. You will also have to allow for the thermal resistance of the adhesive, which I'll suggest that as a DIYer you won't be able to make particularly thin.

I expect that principal advantage of this form of construction comes from the very thin dielectric layer. If you can't reduce this to a similar thickness, the DIY route seems implausible. Although, flexible PCBs can be ordered and their flexible substrate is very thin. You'd still have the adhesive thickness issue though.

Remember that the thermal source is the LEDs not the MOSFET (typically unless serious PWM). So do you actually need a metal PCB? Or can you simply build this thing traditionally and mount the LEDs with dielectric onto a heat sink? Or no dielectric - most high power LEDs already have provision for direct heat sink mounting.

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  • \$\begingroup\$ I wonder if 3M thermally conductive tape can be used for dielectric layer. Most of them feature quite high (25 to 50 kV/mm) dielectric strength, but operating temperature is limited to 150ºC solutions.3m.com/wps/portal/3M/en_US/Electronics_NA/Electronics/… \$\endgroup\$ – Volodymyr Smotesko Jun 2 '17 at 11:06
  • \$\begingroup\$ Kapton tape as a dielectric? With sticky backed copper foil? Hackish and you will not be able to via down to the metal at all easily, but for a prototype, maybe, just maybe? \$\endgroup\$ – Dan Mills Jun 2 '17 at 14:45
  • \$\begingroup\$ Thanks very much! I ended up buying 2 LED star packages (already soldered to small MCPCB's) and and wired them up manually with a custom heatsink. \$\endgroup\$ – Ismail Degani Jul 4 '17 at 0:31
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Try using Mica-silicone mix as dielectric and using polyurethane as adhesive and applying pressure to make the adhesive layer thin.

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