All of the talk about the new Cree is contagious. I haven't ordered any yet, but probably will soon. One of the problems with doing a mod with these led's appears to be soldering the emitter to a heat sink. I though I would try to figure out a way to do the soldering before figuring out the mod.
Here is the setup. 10" cast iron frying pan with lid, oven thermometer, two aluminum foil spacers, aluminum foil workpiece tray.
Process
1. Fold some aluminum foil to form two spacers about 2" square. The spacers should be sturdy enough to support the weight of the thermometer, and be open on two sides to allow air to flow. They should sit flat and level and ½" off the bottom of the pan.
2. Put the two spacers and oven thermometer in the pan and cover.
3. Find a setting on your stove that will stabilize the temperatue in the pan at about 220-230C. On my stove that was halfway between medium and medium low. It may take a half hour for the heavy pan to get up to temperature. Be patient. If you keep adjusting the knob the temperature will never stabilize. Don't keep opening the lid to look inside.
4. Fold some foil to make a sturdy workpiece tray. Apply some solderpaste to the led and heatsink. When the temp is stabile, quickly remove the cover, place the workpiece tray on the second spacer and recover.
5. Cook for 4 minutes. Remove the cover and turn off the heat. Allow the solder to cool slowly in the pan to room temperature.
Here are some pics of some soldering with this setup. It shows a piece of FR4 with copper foil and a copper penny with solder reflowed on top. Also a piece of copper pipe that was split and flattened, two pieces were soldered together. I tried to solder an old Lux I to the cooper. Forgot that slug was aluminum Duuhh!
A glass cover would be better so you can monitor the process. I quickly lifted the cover every minute to peek inside. I took about 90 seconds for the solder to flow. This means that the 2 degreesC/sec. temperature rise specified in the Cree spec is not exceeded. I do soldering in production reflow ovens all the time, and this is not very different from the heat profile that would normally be used. This will also prevent the led from being overheated.
Thoroughly clean the pan and cover before using it for food because it may be contaminated with solder and flux. Hope this helps. Now I have to figure out this whole reflector thing.
Here is the setup. 10" cast iron frying pan with lid, oven thermometer, two aluminum foil spacers, aluminum foil workpiece tray.
Process
1. Fold some aluminum foil to form two spacers about 2" square. The spacers should be sturdy enough to support the weight of the thermometer, and be open on two sides to allow air to flow. They should sit flat and level and ½" off the bottom of the pan.
2. Put the two spacers and oven thermometer in the pan and cover.
3. Find a setting on your stove that will stabilize the temperatue in the pan at about 220-230C. On my stove that was halfway between medium and medium low. It may take a half hour for the heavy pan to get up to temperature. Be patient. If you keep adjusting the knob the temperature will never stabilize. Don't keep opening the lid to look inside.
4. Fold some foil to make a sturdy workpiece tray. Apply some solderpaste to the led and heatsink. When the temp is stabile, quickly remove the cover, place the workpiece tray on the second spacer and recover.
5. Cook for 4 minutes. Remove the cover and turn off the heat. Allow the solder to cool slowly in the pan to room temperature.
Here are some pics of some soldering with this setup. It shows a piece of FR4 with copper foil and a copper penny with solder reflowed on top. Also a piece of copper pipe that was split and flattened, two pieces were soldered together. I tried to solder an old Lux I to the cooper. Forgot that slug was aluminum Duuhh!
A glass cover would be better so you can monitor the process. I quickly lifted the cover every minute to peek inside. I took about 90 seconds for the solder to flow. This means that the 2 degreesC/sec. temperature rise specified in the Cree spec is not exceeded. I do soldering in production reflow ovens all the time, and this is not very different from the heat profile that would normally be used. This will also prevent the led from being overheated.
Thoroughly clean the pan and cover before using it for food because it may be contaminated with solder and flux. Hope this helps. Now I have to figure out this whole reflector thing.