soldering led's?

[geckoejon]

hello,

i bought a 30 Watt Cree XPE Blue Red Multichip LED + 30W LED Driver off ebay to try on my fuge. i am having trouble getting the solder to stick to the led chip / board though. the solder will melt to the wires, but will not stick to the board.

i'm wondering if i'm just not getting the board hot enough, or if i have the wrong type of solder. this is my first time trying to solder wires. i borrowed a battery powered soldering gun.

thoughts?

 

[pwreef]

You need more powerful soldering iron.

 

[Stbobo]

You need more powerful soldering iron.

+1

Your chip should have a designated spot for soldering. If the solder is not melting on this spot, you do not have the solder hot enough to bond.

Try placing a drop of solder onto the chip itself and then bonding the coated wire into the droplet. If the soldering gun can not melt/bond the soldered spot on the chip - you need a hotter gun.

 

[zachts]

Also best to "tin" the solder pads on the LED chip (melt a bit of solder onto the pad) before mounting the chip to a heatsink. Then as Stbobo said just melt the tined wire into the solder blob on the chip. Be careful not to short the wire to the edge of the MCPCB in the process and check for shorts before powering it up.

 

[geckoejon]

thanks for the info! i believe that the gun just isn't getting it hot enough. i'll see if i can find another one and try again...

 

[geckoejon]

i bought a cheap clamp light and led bulb from hd to get the fuge cooking until i can get this one going. i'm seriously curious to see how this led setup does though... anyone every use one of these?

 

[Yodeling]

Make sure your solder has a flux (rosin) core. If not, you do have the wrong solder as it needs flux to stick properly. The proper way to solder is to touch the iron to the pad, then flow the solder to the pad. With LEDs though other techniques should work just as well. Make sure your tip is clean and that you tin the tip slightly before soldering. With lower power irons, you may need to wait 5-10 minutes for the iron to get sufficiently hot.

 

[Mike31154]

Flux is also available separately if you don't have rosin core solder. It's quite corrosive, so you need to take care & clean the solder joint once you're done. Pretty much same idea as assembling copper pipe, the flux ensures all surfaces are super clean by acid etching the mating surfaces, allowing the solder to flow freely & seal all crevices.

 

[geckoejon]

yodeling & mike31154, thanks for the tip on the flux. i was wondering. i've done plenty of soldering on copper pipe. i'm an a/c service tech for commercial and industrial sites.

i will get some flux, and work on heating it up more. thanks....

 

[Webmanny]

Just my two cents and I have done plenty of DIY builds. I learned two things with soldering LEDs.

1- The gun has to be above 30watts and cleaned often
2- It is better to apply solder to the board first and then bring in the led to the board


I Also agree with the flux comments above. I use a solder that combines flux and rosin. It makes things easier on me.

Good luck!!!

 

[hllywd]

I found using a Kester Flux Pen worked wonders on the pads. Apply it and solder away.

 

[perkint]

If the solder is melting on the wire but not sticking to the solder pads on the LED, it sounds to me like you haven't tinned the solder pads first. If yyou try that it should make life much easier

Tim

 

[DaveMorris]

Keep in mind that you can also overheat the LEDs and ruin them. I would caution the comparison of soldering copper pipe and soldering electrical wires. While the process is very similar, if you use flux designed for working with copper pipe your connection will be completely corroded away in a few months. Rosin core solder is your best choice.

 

[hllywd]

yodeling & mike31154, thanks for the tip on the flux. i was wondering. i've done plenty of soldering on copper pipe. i'm an a/c service tech for commercial and industrial sites.

i will get some flux, and work on heating it up more. thanks....

Good catch DaveMorris, I must have skipped over the plumbing reference. DO NOT use plumbing flux. It's not the same thing and over time may (will likely) cause your solder joints to fail. The flux used in solder is non-corrosive.

Part of your soldering problems could be the specific solder you're using, along with the type of hook up wire. It's possible the solder doesn't have enough flux for both the wire, and the pad you're trying to solder it to, and that's assuming you're using electronic rosin core solder to begin with. A fine gauge electronic rosin core solder is a must! I mentioned using a Kester Flux Pen. It's like a magic marker, only rather than ink, it has an electronic type flux in it. It's extremely simple to dab a "mark" on each pad you intend to solder without adding too much. It makes a remarkable difference in how the solder flows onto the pad, and there is little chance of making a mess.

I'm not sure what kind of "battery powered gun" you have, but it may simply not generate enough heat. That, with the possibility of not enough flux will contribute to all sorts of soldering faults, cold joints, solder balls, slivers, porous joints with rosin remaining.... and the list goes on! I have a Weller WPL100 - 40W iron that does a great job, and can be had for $50. You can spend much more for greater quality, or if you plan to use it a lot. I had a rechargeable iron years ago that might have worked, but IME they tend to be limited in the heat they can provide to make the solder not only "melt", but flow correctly. Soldering "guns" pale in comparison to a nice pen type iron, they are not a good choice for working on electronic circuitry.

For putting together LEDs I like a 1/16" tip on the iron. It doesn't carry a lot of heat, but it concentrates it onto a very small area perfect, at least, for
regular stars. It needs to be cleaned, and tinned regularly during the build.

Good luck, hope that helps!