Soldering xp-g

[LED4LYF]

I have bought some xp-g R5 on the 10mm round mpcb board and I have a few questions.

1. Can I solder to the small pads on top of the led?

2. Do the pads on top have a protective coating? How do I remove it?

3. Is the negative side of the LED (-pad on top) connected physically to the mpcb?

4. Any tips on soldering to xp-g with mpcb?

 

[chelboed]

I'm a little curious about the XP-G too.

Whoever answers the above Q's...please answer this one too.

If I were to Arctic Alu Adhesive the bare LED Emitter to the heatsink and solder the leads to the tiny square +/- terminals...do I need to insulate the bottom metal strips of the emitter from the heatsink so I don't short out...do the metal strips on bottom conduct any electricity?

I just wanna glue it to the sink and solder leads to the top of the boards.

 

[Justin Case]

LED4LYF,

Did you look at this very recent thread?

chelboed,

The metal LED+ and LED- strips on the XP-G had better conduct electricity since they need to be connected to the MCPCB. How else will you get continuity to the LED when you solder your hookup wires to the hookup wire solder points on the top of the MCPCB?

Look at the XP-G datasheet. Examine the recommended PCB solder pad configuration shown near the end of the document. The wider center strip connects to the XP-G slug and is for heat sinking. The two narrower pads connect to the LED+ and LED- on the XP-G. Notice the two small pad protrusions coming out of those two narrow, outer pads. Those small protrusions connect to the hookup wire solder points on the top of the MCPCB. That's the electrical path from the hookup wire solder points to the MCPCB pads to the XP-G LED+ and LED- connections.

Your Arctic Alumina adhesive is already an insulator. If your heat sink is anodized, the anodized layer is also an insulator.

 

[LED4LYF]

Ok that makes sense, so is the negative pad on top connected to the mcpcb?

If I hook up a battery to my xp-g the led will light up.So is there a thin layer of protection on the top pads, because it did not seem like there was.

 

[JetfuelGreaseMonkey]

Yes, in theory you could solder directly to the little contacts on the led, but you don't need to if yours came already mounted to a board (aka MCPCB). The xp-g, and most other cree leds, have through holes at the edges which conduct directly to respective pad on the bottom of the led itself.

Because yours (as you describe them) are mounted all you need to do is solder to the larger exposed + and - pads on the MCPCB. Just be carefull with heat. Too much and you melt the solder holding the cree to the board. Too little and your wire solder joint might not bond to the solder pad (aka cold solder joint). Its not too difficult with even a regular soldering iron, if you want examples of it being done they are available here and on y-tube.