About the time that everyone caught wind of the International Outdoor Copper MCPCB for XM-L and XP-E/G, Hank from International Outdoor got in touch with me and asked if he could send me a couple of them to review. I agreed.
These are pre-production versions, and I understand that that silk-screen markings on them will be changing, but otherwise they’re the same as what one would expect to be able to buy later this month.
These were sent to me at no cost by Hank - just for full disclosure.
So, Here’s the MCPCB. Direct Thermal Attach with no insulator between the base material and the thermal pad on the LED. Copper is very lightly gold plated to prevent tarnishing. Surprisingly, the bottom side of the PCB is also gold plated which is great!
The top of the electrical pads is perfectly planar with the top of the center slug - as should be expected.
On one of the samples I received, I cut away the insulation layer to expose the base copper. This shows quite nicely how the center thermal slug is solid copper rising out of the base.
On some MCPCBs, the insulating layer is not very well attached to the base copper, and it can detach itself during the extreme heat of reflow. I heated the whole MCPCB up to 250 degrees C and used a sharp blade to try and separate the layers of the PCB. I was unsuccessful. The layers of the PCB are very well joined together.
The footprint for the XM-L is perfect with the proper solder mask openings to allow excess solder to escape - this helps to assure that all three connections are made without the emitter floating too high off of the MCPCB.
The samples I received are 15.93MM in diameter, the base copper material is 1.25MM and the overall thickness is 1.5MM. The back side of the MCPCB that would attach to the pill or heatsink is very flat with only very minor burring around the edge. 30 seconds with sandpaper or a file would leave you with a very good thermal junction.
Here’s a video showing the MCPCB at different angles.
The primary competitor to this board will be the SinkPAD board available from several members. As surprised as I am, these boards are better in one important way. The back side is completely flat and does not have a punched out center slug. This means that the (most important) area directly below the emitter is making contact with the pill/heatsink. This is quite a benefit!
I was curious how much difference the extra contact area would make, so I ran a thermal simulation on two identical MCPCBs - One with the punched out slug and one without. These numbers should only be used as a comparison between the two styles of MCPCB - not as an expectation of what absolute temperature an emitter will run at. I used an ‘infinite’ heat-sink as I only wanted to see the difference in temperature rise through the board with no attention paid to the type of heatsink or host.
SinkPAD style Punched Thermal Pad:
INTL-OUTDOOR Style Flat Bottom
As I expected - There is a measurable difference! Having direct contact with the heat-sink right under the emitter makes a difference.
I’m very pleased with these boards from Intl-Outdoor, and I thank Hank for giving me the opportunity to see them in advance of their public availability. I’ll be buying more of these as soon as they are available.
If I was forced to come up with one complaint, it would be the wire connection pads. I wish they were just a little bit larger. Not a big complaint, but for those less skilled at soldering, it makes for a small connection point.
PPtk