You cannot beat the cost of a Bridgelux Gen 2 even if you manufacture your own.
All I want is a 22" strip with 21 deep red LEDs to compliment the Gen 2 boards.
Also I'm wanting this whole board to be water cooled, so what type of PCB will give me the best heat transfer from
I have some Gerber files for the 12" strips at the bottom of this post.
Free, I am not a commercial entity. I do not sell anything. I do consulting and I do not need any more clients. I have 20 years experience with my own telecom manufacturing business.
This12" strip was for an intra-canopy project.
22" is the most economical size. The most common PCB panel is 16 x 22. I can put up to 45 strips per panel. Less would be easier to separate the boards.
But at the same time I wanted to run some thermal tests with water cooling.
Traditional cooling is to make thermal vias through the PCB and mount the heatsink on the back side.
Thermal vias were useless.
Thermal pad for a Luxeon Rebel with thermal vias.
Because the thermal pad is on the component side I figured it would be best to mount a heatsink on the same side of the PCB as the thermal pad.
Very effective. The temperature of the thermal pad was very close to the temperature of the water.
The copper pipe also doubles as the frame to the fixture.
This shows the thermal path. It is an all copper path from the thermal pad of the LED to a 1/2" water pipe.
(Hand soldered)
I spent months running various thermal experiments. The CoBs here were only heat generators to measure heat flux. Thermal dynamics is complex. You can not calculate heat transfer very accurately. You must try it. Cost for the heatsink, copper bar and pipe is about $3.00 per foot.
At the bottom I tried to mount the strip to a copper bar, bent the ends to the curve of the pipe and connected the bar over the top of the pipe. Did not work well enough.
This layout is for Cree XP and Luxeon Rebel. 32 LEDs powered two strips of 16 LEDs. Forward voltage for blue and white ≈45v to be powered by a 48v or 54v driver. OSRAM Olson SSL can be mounted as well. Each strip is 0.7" wide. I have a new layout that is 0.35" wide Cut the price in half.
The new ones, if I proceed, will be 22" long. 4 strings per strip. I have the layout for a 16x22 PCB panel. Some are strings of 16 and some are strings of 21v. So the forward voltages of the white and blues will match the reds. White, today, you cannot beat the Bridgelux Gen 2. I could not manufacture a 44" strip for $14.
This is my new layout for Cree XP and OSRAM Olson SSL 150.
To get the width down to 0.35" with multiple strings was challenging.
Until I cam up with the idea to use four different footprints, one for each string.
The routing became very simple. I added vias to each pad at different levels for each string.
The "big" black holes are the screw holes for a little 4-40 or 3 mm machine screw.
If I could find a reasonably priced deep red to complement the Bridelux Gen 2, this project would not exist.
I could not find a deep red mid-power (≈ 0.2-0.3w) LED. Buying by the reel, deep red LEDs are $1-$2. At 21 LEDs per 22" string I'm looking at about $30 parts cost. Plus assembly.