Help needed with connecting Cree XPG R5...

Hi guys,

I recently bought a pair of CREE XPG R5 LEDs thinking it would come with the 10mm dia' aluminium heatsink which is quite easy to solder. However it arrived as bare LEDs and due to their tiny size I've no idea how to connect/solder them. It would probably cost me more to post them back, so I was wondering if someone can advise me on how to connect/solder them.

Many thanks

CTR

A few options:

1) You can buy the MCPCB alone and reflow solder them.

2) You can carefully glue 3 copper strips onto your annodised aluminium (so it doesn't conduct electricity) heatsink and reflow solder the LED onto them.

3) You can solder your wires underneath the LED and glue the thermal (central) pad to a heatsink with a thin, raised platform.

4) You can scrape a little silicon off the top of the LED to reveal the (tiny) solder pads. Then glue the LED to the heatsink (keep the pads electrically isolated).


My opinion:

Easiest to hardest: 1,2,3,4

Best to worst thermally - 2,4,3,1

The three strips on the bottom are the key. The middle one is heat-conductive, and the two on the sides are electrically-conductive. I use snipped-off 5mm LED leads to connect them, and I fill in the gaps with heatsink epoxy. For the center strip, just stick two 5mm LED leads side-by-side, solder them in place, snip them off at the edges of the emitter, and there's your conduction path.

I don't have any solder paste atm so I think this is where I'm struggling to connect up the terminals. I haven't actually used solder paste before, but from what I understand, you simply...

1. clean the terminals with flux
2. apply solder paste
3. offer up component
4. apply heat

My main problem is it being so small, the connection terminals on the base are impossible (for me at least) to solder to using a soldering iron and a coil of solder. I don't have a MCPCB, but I think this is probably the only way I can do it along with some solder paste.

I can't seem to find any cheap lead-free solder paste though or where to get a MCPCB board from. Any pointers guys (I'm in UK btw)?

CTR said:

I can't seem to find any cheap lead-free solder paste though or where to get a MCPCB board from. Any pointers guys (I'm in UK btw)?

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You can get a 5-pack of 14mm round XP-E (same layout as XP-G) MCPCBs from KD for $2.10.

Black Rose said:

You can get a 5-pack of 14mm round XP-E (same layout as XP-G) MCPCBs from KD for $2.10.

Click to expand...

Thanks! But I've no idea what KD is? :thinking: Do you have a link?

CTR said:

Thanks! But I've no idea what KD is? :thinking: Do you have a link?

Click to expand...

Kaidomain.com