Heatsink Base Thickness

I have stumbled upon some pinfin heatsink but am afraid the base may be too thick to be of use. They have a 15mm base and I would be using them on The previous generation of Vero 18s being ran at 1050mah.

I know many of the kits come with the pinfin heatsink with a 10mm base. Would 15mm work or would it be too thick to properly transfer the heat and cause a build up and overheat the cob?

You would need the Thermal resistance of the heat sink to do a proper calculation. This link might help https://www.led-heatsink.com/thermal-calculation

Thanks but that link doesn’t show me how to figure what the thermal resistance of the heatsink would be, just how to figure out what would be a maximum thermal resistance allowable for proper function.

Isn't it actually better to have a thicker base?

aluminum is extremely heat conductive. extra thickness only helps in dissipation away from chip

More mass and surface area is always better.

More mass only means it will take longer to start moving the temperature up or down from where it is, but have zero effect on the temperature reached in the long term.
And it works both ways. If you melt a cup and a kilo of water, the resulting water will be the same temperature, one will only take longer.

Surface area can also be tricky, as the heat can only travel a fixed distance based on the thickness of the material. Orientation would also play a role, I vertical heatsink would receive a faster moving stream of surrounding air molecules than a horizontal one, as the hot air has nowhere easy to go.

Well there has to be some optimum value for the base thickness. If it's say 1 mm thick or less, it won't be able to transport the heat from the COB to the pins properly. So increasing the thickness from there will improve the heat sink, but at some point indeed increasing the base thickness will stop improving the heat transfer. Adding more mass will just delay the temperature stabilization, but the end temperature will remain the same yes.

Either way, adding more thickness would not decrease the performance of the heat sink. In this case, going from 10mm to 15mm, I would think it actually still helps with conducting the heat to the pins better. So it would improve. Not sure how to calculate this though.

SupraSPL did some tests a few years back and he found that a CPU heat sink with a thicker base worked better than one with a thin base. But then 10mm would already classify as a thick base I would say.

J-Icky said:

Thanks but that link doesn’t show me how to figure what the thermal resistance of the heatsink would be, just how to figure out what would be a maximum thermal resistance allowable for proper function.

Click to expand...

Who ever is selling you the heat sinks should know the thermal resistance. If not maybe try and find manufacturer or one the same size on a heat sink web site to get the numbers off.

http://www.heatsinkusa.com/faqs/

°C/W/3" Information

We have provided Approximate °C/W/3" ratings for each profile which can be found in the specifications on the product page. They are also included in our currently available profiles sheet. These approximate °C/W/3" values are based on natural convection: 70 C temp rise above ambient, based on a single 1" (25.4mm) square heat source centered on the heat sink. If you have distributed loads, then you can expect about a 10% better performance in natural convection and 20% better performance in forced convection. We STRONGLY recommend customers perform their own thermal testing in relation to your specific project.

the calculator ->https://www.heatsinkcalculator.com/calculator_heatsinkusa.html