Attaching LED to MCPCB?!

So my Ledengin diodes and MCPCBs arrived. Having a little inspection and looking at the MCPCB, im worried. The thermal slug and the contact pads actually seem to be slightly recessed into the PCB, while the bottom of the diode is flat, so how am I going to make a good thermal or electrical contact?! there is actually a tiny gap between the LED's contacts and the pads on the PCB. Seems to me it is designed with reflow in mind, but even then I would expect the recession into the MCPCB to be too deep and cause one to need an excessive thickness of solder.

I'm going to try soldering with an iron tonight and see what happens, probably waste a diode which sux but oh well. If it doesn't work i'll be learning to reflow i guess. If anyone has some input I would greatly appreciate it.

The other things I thought of (to avoid reflowing) were using copper tape to raise the electrical contacts so i have a circuit at least, or some kind of electrically conductive glue. Sounds dumb though.

also, WTF: liquid solder/solder paste seems to be extortionately expensive. Ouch :/

SnotBoogie said:

also, WTF: liquid solder/solder paste seems to be extortionately expensive. Ouch :/

Click to expand...

Yup....
But is worth it ....
Can make your own ...
If you find a way to pulverize solder ....

As for the small gaps ....
Macro pics would not be,such a bad idea ....(with a small ruler by the side ,even better .. )

Iron plate for clothes, upside down: secure it firmly. Easy ( I've done it) I even have a hot gun which I thought I was gonna use in the process..
But I've done without it better!

Get a decent paste, they are decent as they are not the adhesive type which costs more to be decent!

All you'll have to do is put a small amount of paste on the mcpcb along the connectors bits, tweezers your LEDs on top of it and place the lot on the iron plate. It's a matter of 30 seconds. You could preheat for a minute that go higher in temp and will melt soon! What I did, not too high not too low temp and melted nicely after 30 seconds.

The diode will place itself in the right spot during the melting process; sometimes it will move wrongly but that's when you are there ready to adjust it with tweezers

It's even easier than using a soldering iron for golden dragon's for es.

Hmm clothes iron is a good idea. Any pointers on a "good" solder paste? Thanks a lot guys.

No photos right now but i would guess the recessed pads to be about 0.1-0.2mm "deep".

0.1-0.2mm "deep".



That is way much ....
Are you sure ?

0.1mm, as in a tenth of one millimetre. its a noticeable indent if you run your nail over it. pressing down the LED onto the MCPCB, there is no electrical contact.

edit: and could i ask again for solder paste recommendations guys? Its something which I dont want to buy the wrong one, looking at the price...

if you see something lke this

No-Clean SMD ....than pay for it

http://www.edsyn.com/

2.5ml is good for more then 100 Leds

Thanks so much guys! now to sit on my hands for couple days messing around with chinese diodes and my box of ebay heatsinks