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Thread: CREE XR-E emitter Hand Soldering? (No star)

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    Help CREE XR-E emitter Hand Soldering? (No star)

    I recently purchased (3) Q5 XRE emitters intent on using them in a DIY bike light. Post-purchase research revealed Cree soldering and handling datasheet "doesn't recommend" hand soldering (recommends reflow), I seek advice re:mounting/soldering.

    *post purchase research shows product temperature sensitive and performance/lifespan will be affected drastically by proper installation.

    *I don't want to destroy my LED's by hand soldering at high temperatures.

    *Have seen on-line references to "toaster over" reflow soldering, or attaching electrical leads with electrically conductive adhesives.
    ANY THOUGHTS?
    Last edited by Lightening; 10-30-2007 at 07:29 PM. Reason: Update

  2. #2
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    Default Re: CREE XR-E emitter Hand Soldering?

    you dont want to know one of my methods :-)
    clip the corners to get rid of the conduction, tin with solder the base of the emitter. put heat sinc on gas stove, gas up heat sinc to JUST where the solder melts, then drop the emitter in, wait Just long enough for the emitters solder to melt, try and push the thing down into the pool of "mercury" that is pushing it back up, and try and stop the heat immediatally. if you only get 3rd degree burns, and have the emitter aimed more than 30* and 5mm offset, then you won
    then try and solder on the TOP of the dang thing, without making to many attachements to the ring around the dome. which sombody convienientally tinned so it would accept solder better than the copper pads

    wont do that again, ok only 2 times, for me, i want a star.
    Last edited by VidPro; 10-29-2007 at 04:06 AM.

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    datiLED's Avatar
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    Default Re: CREE XR-E emitter Hand Soldering?

    I have not had a problem with hand soldering the CREE emitters. I use a little paste flux on the very edge of the emitter, near the corner, and pre-tin the pad. Then with pre-tinned wire, and a little more flux, I just barely have to touch the pad and wire to get a good solder joint.

    FWIW, I have a good temperature controlled soldering station, and use a fine tip on the iron.

    As VidPro mentioned, avoid the metal ring of the LED. It will attract the solder better than the actual solder pad.
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    Default Re: CREE XR-E emitter Hand Soldering?

    I've hand soldered mine. Started off by making some copper strips the same width as the heat pad on the base. Tinned the copper strip in the middle and then heated the strip up with an iron to get the solder to flow pressed the LED in place (used some flux on the LED pad). You can then hand solder to the bottom of the LED since the copper strip gives you clearance.

    Not sure I'd bother going that way again - will probably snip the corners and solder to the top (then glue the base with epoxy - slightly worse heat transfer, but less risk of damage).

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    Flashaholic* Long John's Avatar
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    Default Re: CREE XR-E emitter Hand Soldering?

    Quote Originally Posted by chris_m View Post
    ......- will probably snip the corners and solder to the top (then glue the base with epoxy - slightly worse heat transfer, but less risk of damage).
    +1

    That's a proven and reliable method. In my cases up to 1,2A with a propper heatsink.

    Best regards

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    I scrape the back contacts away with an X-acto, when snipping the corners there is not so much pad around.

    Then, before mounting, use the solder iron to get some solder onto the top contacts,
    mount the emitter,
    use normal iron to solder in the wires
    --> ready to go.

    PS: instead of the 15 W iron I use for every other soldering, I use the 100 W here, the Cree moves the heat away too quick and the small iron is simply not powerful enough

  7. #7

    Default Re: CREE XR-E emitter Hand Soldering?

    Did you just get bare emitters, or star-mounted items? The stars will be immensely easier, as Crees are not suited to hand soldering. OTOH, they make soldering Luxes and Seouls seem like a breeze by comparison.

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    Flashaholic* 3rd_shift's Avatar
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    Default Re: CREE XR-E emitter Hand Soldering?

    Quote Originally Posted by TigerhawkT3 View Post
    Did you just get bare emitters, or star-mounted items? The stars will be immensely easier, as Crees are not suited to hand soldering. OTOH, they make soldering Luxes and Seouls seem like a breeze by comparison.
    Agreed 100 hundred percent.

    Although, hand soldering is possible with a small soldering tip, prefluxing the contact points with rosin type flux, using small guage electronics solder, and use some patience too.
    I have been there and done that too, successfully.

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    Default Re: CREE XR-E emitter Hand Soldering?

    I'm glad you asked this question... I tried my hand at my first Cree XRE emitter the other day with a 15 watt iron and it wasn't pleasant. I like the suggestion of using a higher wattage iron as I seem to be having a difficult time as well. Could someone recommend a particular flux/flux paste? All I've got access to is some Radio Shack rosin flux. I don't like the residue it leaves.
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    Flashaholic* Erasmus's Avatar
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    Default Re: CREE XR-E emitter Hand Soldering?

    Get an iron of at least 25W, you'll see that's already a huge improvement.

    How I do it : snip the corners and mount with Arctic Silver, or Arctic Silver Thermal Compound where they really need to be attached. It's an easy method, and the heat transfer is much better than with stars/boards.
    Last edited by Erasmus; 10-30-2007 at 04:07 AM.

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    Default Re: CREE XR-E emitter Hand Soldering?

    Quote Originally Posted by bluecrow76 View Post
    I'm glad you asked this question... I tried my hand at my first Cree XRE emitter the other day with a 15 watt iron and it wasn't pleasant.
    +1

    I must have spent 30 or so mins trying to solder the wires on an emitter. Eventually the solder stuck at the corners of the pads on top. Seems like a higher power soldering iron is the trick. Why do you guys snip the corners?

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    theres the connection to the contacts on the back side of the emitter - might short itself out when the sink is conductive.

    (with some emitters I got the slight impression, that the slug is extending just a little bit over the contacts, so theres no need for additional work. Anyone can give thoughts on this?)

  13. #13

    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    For me, the solder contacts on the top of the cree do not willingly take solder. Any tips? Do I need to sand off a protective layer on the pads or something?

  14. #14

    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    Quote Originally Posted by Gomer View Post
    For me, the solder contacts on the top of the cree do not willingly take solder. Any tips? Do I need to sand off a protective layer on the pads or something?
    It's possible that the metalization is gone. Sometimes it's not obvious, since whatever is beneath the metalization looks somewhat similar. The metal of metalized ceramic tends to dissolve in regular solder. Depending on a number of factors, you might be able to solder and de-solder several times before it's gone altogether, but eventually it disappears. The solution is to use solder which contains 2 - 3% silver whenever soldering to metalized ceramic components like Cree emitters and surface mount components.

    Don't know if that's the problem here, but it's something that everyone doing mods should be aware of. Radio Shack used to sell silver-loaded solder, but I don't know if they still do.

    Note: Don't confuse this with "silver solder", which is a term often used for a hard, high-temperature solder used in brazing.

    c_c

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    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    Quote Originally Posted by Gomer View Post
    For me, the solder contacts on the top of the cree do not willingly take solder. Any tips? Do I need to sand off a protective layer on the pads or something?
    we used to use a pencil eraser on "card edge connectors" to clean off the oxidation , because they are very thin, and that would work on the card edge connects without shredding them, wont work here because you will clean that evil dome ring :-).

    if i sanded before pre-tinning on them things , it would be with 600-1000 type alum-oxide sand paper (really light sanding) as opposed to emery board or other methods, and avoid the dome ring like a plauge.
    manually cleaning any oxided metal surface, or one that has some machined coating on it, works great to get solder where you want it to land.

    then pre-tin it, before heat sinking, in those situations where you have to sinc before soldering.
    Last edited by VidPro; 12-21-2007 at 04:07 AM.

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    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    Quote Originally Posted by yellow View Post
    theres the connection to the contacts on the back side of the emitter - might short itself out when the sink is conductive.

    (with some emitters I got the slight impression, that the slug is extending just a little bit over the contacts, so theres no need for additional work. Anyone can give thoughts on this?)
    they do, even if you epoxy and clamp, there can be metal to metal connection to the bottom conductors. that is why you grind, or clip off the corners. even if you just grind the bottom corners off so its a bit higher, you dont have to completly clip off the whole corner. there are "vias" in these corners that connect the top to the bottom.

    i had a pic around here, but cant find it.

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    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    while swapping the Q5 emitter from the P4 in my P1DCE (sold to a friend) i barely attached the solder to the Q5 but it works - after that i quickly apply some thermal paste glue like and it stay there ever since.But to solder the lead wires to the Q5 is really is a PITA.But i manage to complete it under 10 minutes with proper study before it all began.



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    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    I just went through this again with a Cree XRE Q5 bin led yesterday.

    Snipping off the corners of the emitter's ceramic base detaches the contacts underneath to prevent short circuiting to any heatsink underneath.
    Look closely as you will notice thin copper wires were formed into the ceramic base at the corners.
    These little buggers connect the top and bottom contacts to each other through the non conductive ceramic base.
    Those need to go bye-bye with wire cutters, or dikes, but only take off as much as neccessary to achieve this, or there won't be much left to solder onto on top.

    Most types of electronics solder flux do leave a residue.
    This is normal.
    Just use it somewhat sparingly and evenly onto whatever is getting soldered, but enough to get the job done smoothly and quickly.

    Soldering iron?
    Higher power (45+ watts) with a small tip seems to be the winning formula for this.
    Makes fast, production line speed, "hit and run" soldering easier to achieve.
    Some 25-30 watt "name brand" irons are about as good too if you already have one.

    Good luck.

  19. #19

    Default Re: CREE XR-E emitter Hand Soldering? (No star)

    I used a portable soldering iron (equivalent to about 50 watts) and some white, non-conducting thermal compound and just soldered very quickly. Just don't heat the emitter for too long or else the silicone under the glass will 'crack', leaving you with an wrecked beam profile. The Crees are pretty tough otherwise.

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