How to reflow leds onto star?

Ordered a few leds and stars and was wondering if anyone knows of a good way to get it done.

Have a griddle with a temp control...lol. Or maybe a flat top range?

maybe some of that chipquik solder paste?

any help would be appreciated, I'd hate to fry too many trying to figure it out.

https://www.rollitup.org/led-other-lighting/667365-led-diy-reflowing-home-yes.html I was pretty sure the space monkey took a whack at this. Probably a good place to start. Frying LEDs is soooo depressing

try youtube

Good call on the chipquick. It melts at 137C which is well below the "critical zone".

Thanks for the input. After reading the sds thread and watching youtube I think I got this.

I'll be reflowing the osram red 3t4t bin on a sinkpad. Going to go with the hot air gun and chipquik technique. The heat gun should give me good control of the heat and the chipquik solder paste should allow a lower temp reflow. People seem to have good success with normal solder so the chipquik should be even gentler on the led.

i like the reflow toaster idea, looks almost doable, but I'll try this first. I don't see why I couldn't mimic a solder profile manually vs computer controlled. Not even close to exact I'm sure...but I think it will more than suffice.

it will be a while before I get to this but I'll post back results for any future reflowers.

TNX POS. I ordered some of this tin/bismuth solder paste, copper XML2 stars from eBay and XML2 T4 7a4 from aliexpress. Gonna try this with my 60W iron.

To reflow solder successfully ceramic leds into mcpcb stars ,is not such difficult job ...
Her's some advices :

-Solder that MUST be used has to fall within the JEDEC J-STD-020C standards.
That being usually solder alloys containg Ag (silver ) .
Due to silvers extreme thermal durability ,oxidation resistance,low gas absorbtion during liquidus phase and some more ..

The usuall solder alloy used for the best and quality reflow is SnAg3Cu.5 .

tin/bismuth solder ,like the Sn42/Bi58 ,tend to absorb gasses from atmospheric air ,thus final solder point has bad thermal conductance characteristics and
heat from leds will 'ages the solder prematurely ...
Also this alloy is brittle enough ,to point that a solder point can fail under different thermal expansion coeffs of
Solder alloy ,ceramic of led (AlO or AlN )and pcb copper pad ...
This solder type,ain't for high power leds ...

(...)Alloy for low temperature applications. Attention should be

paid to potential embrittlement issues and poor thermal
fatigue properties. (...)

http://www.aimsolder.com/sites/default/files/lead-free_alloy_information.pdf

Click to expand...

-Get a multimeter with a K-type thermocouple thermometer feature (cheap ones $5-10 are more than fine )

Attach the tip of the thermocouple to the kitchen stove plate (use plenty of capton tape ) ..
Not on the mcpcb star ! ( .............................^^^^^ ^^^this way you play safe !! )

Get a timer / clock ....

At same time pay attention to multimeters display ,the time and the solder profile ....
Your hand at the stoves heat adjustment knob (usually marked 1 to 9 )

Try to follow the solder reflow profile .
Keep the temperature ramps ,in relation with time ,as close to the solder profile.
Manually ,I trust that one enough experienced ,can achieve really amazing results !!
Use some old stars / fried leds .Not the new ones !!!
After the third-fourth time ,you will realise that is actually a piece of cake ...
Reflow solder and unsolder (use tweezers to handle the leds &
make a habit to 'ground '/'earth' yourself with the special wristwrap ),some times more ,
to "master" the procedure ..


Roughly ...For SnAg3.5Cu ,on an 'ordinary' stove plate (medium size ) ..

1) For the first ~30-60 sec ,heat set at " 4 " ( rise from ambient to ~150 C )

2) The next 120 sec ,heat 'plays ' between 3-5 ....Slowly rising to 180-200 C )

3) the next 30 sec heat goes to 6-7-8-9-8-7-6 ..Heat now is about 220,rising to ~ 230-240 C ...

4) Turn off ,totally the heat ....Blow slowly / softly the star with your mouth/fan ..
Move it away from stove plate ,but only when the solder has solidify ....

Keep it near ,at the borders of the stove plate ,so to cool slowly ...

After ~30-40 sec ,remove it and let cool down ....

That was it ...
More or less ...

Practicing on it ,will most probably be very ..'enlightening ' ....



-The "Weak" point of the whole procedure is the cooling state ....

if cooling is done fast ,led die might chip off ,or led case might crack ..
Ceramic leds do tolerate lots of heat abuse ...meaning high temperatures-
nothing there to melt ..Ceramics-metals-semiconductors-silicone ..none of these materials used,melts or deforms under 500-600C...
But not sudden changes of temperature .They can chip or crack ...


-use a ( led ) pad stencil to apply the solder paste in a really thin layer ( 2/10 of one millimeter = 200 micro thickness of solder paste ).
A good solder stencil is the 90% of a successful reflow solder !
Use your imagination ,how to make one ....
That's the most difficult part of all !!!
Making a good pad stencil .

Good luck with that one !

Reflow is actually very easy (regarding a single star mcpcb )...
Needs a bit of practice ...

Oh ..
Almost forgot !

Space Monkey Rules !


They say that I'm a clown
Making too much dirty sound
They say there is no place for little monkey in this town
Nobody'd like to be in my place instead of me
Cause nobody go crazy when I'm bangin' on my boogie

I'm the (king of the bongo, king of the bongo bong)
Hear me when I come, baby
(King of the bongo, king of the bongo bong)
Hear me when I come

[video=youtube;vJMLJVha5sw]http://www.youtube.com/watch?v=vJMLJVha5sw[/video]

Sds> Tried to find that sort of info but wasn't able to. Thanks for catching that, don't want to mislead anyone. Order for chipquik cancelled..

i got the point on slow rise and fall of heat, makes a lot of sense. I'll check into the datasheets on their reflow recommendations.

so you think the stove is better than a hot air gun? I'll give it a try with your recommendations.

the guys on youtube just make it look so easy with the hot air..

Positivity said:

Sds> Tried to find that sort of info but wasn't able to. Thanks for catching that, don't want to mislead anyone. Order for chipquik cancelled..

i got the point on slow rise and fall of heat, makes a lot of sense. I'll check into the datasheets on their reflow recommendations.

so you think the stove is better than a hot air gun? I'll give it a try with your recommendations.

the guys on youtube just make it look so easy with the hot air..

Click to expand...

Hot air gun ?

Maybe the worst of all ,regarding soldering leds ..
Never liked it ...


' Hot plating ' is by far the best DIY method for reflow soldering leds ...
And not only leds .....


(...) Hot Plate Reflowing -
https://www.sparkfun.com/tutorials/59

You need a ' hot plate ' ,that can reach ~ 250 C ...

(Like Cloth iron ,Stove plate,skillet,etc ...)

Once you practice a bit ...

You can achieve amazing results ...



Something like this .....




Tiny Oslons ....




Propane Gas reflow !!!

When heatsink and mcpcbs can't be detached !

Way extreme ...Risk of serious injury or fire !!!





A not so good stencil ..
Though the final solder was ok ..
And led still operates up to date !

(leds and solder ,auto-align themselves-slightly- on the psb's solder pads ..)

Okay, things becoming clearer..

Looked into stencils. That would be great for getting an exact amount of solder paste onto the pads. Only problem is you need to provide a cad drawing to a company to get the stencil made. Nobody sells stencils already designed? I found a cad drawing for the xml l2 that may be useful in the future but right now I need the osram one.

hot plate technique looks good, I'll give that a try.

cree recommends kester r276 solder paste. This should work?

To think I could have avoided all of this, but I don't mind a challenge. I've been thinking about reflowing for a while now..time to get to it.

Amazing to see this done with just a stove. This star + this oslon would be pretty awesome for 3 euro a piece.

https://www.youtube.com/watch?v=JWUJtmgh55M x ... https://www.youtube.com/watch?v=1CkYs-gM4fw ...sds way is better... x ... https://www.youtube.com/watch?v=QRW4gBcsRkY x.... PD...my firefox report this forum como web atacante!!!!! saludos pd2... tellme this... What is the current listing status for rollitup.org? Site is listed as suspicious - visiting this web site may harm your computer. Part of this site was listed for suspicious activity 12 time(s) over the past 90 days. What happened when Google visited this site? Of the 834 pages we tested on the site over the past 90 days, 41 page(s) resulted in malicious software being downloaded and installed without user consent. The last time Google visited this site was on 2014-03-29, and the last time suspicious content was found on this site was on 2014-03-29. Malicious software includes 33 exploit(s). Successful infection resulted in an average of 8 new process(es) on the target machine. Malicious software is hosted on 3 domain(s), including byhnuj.in.ua/, mesinski.com/, bgbyhn.in.ua/. 1 domain(s) appear to be functioning as intermediaries for distributing malware to visitors of this site, including mesinski.com/. This site was hosted on 2 network(s) including AS13335 (CLOUDFLARENET), AS4436 (AS-NLAYER). Has this site acted as an intermediary resulting in further distribution of malware? Over the past 90 days, rollitup.org did not appear to function as an intermediary for the infection of any sites. Has this site hosted malware? No, this site has not hosted malicious software over the past 90 days. How did this happen? In some cases, third parties can add malicious code to legitimate sites, which would cause us to show the warning message. Next steps: Return to the previous page. If you are the owner of this web site, you can request a review of your site using Google Webmaster Tools. More information about the review process is available in Google's Webmaster Help Center.

Trying to find a solder paste, read through lots of recommendations pertaining to leds.

http://alphacpmd.com/~/media/Files/CooksonElectronics/ETormey et al SMTAI 2011 Final 08082011.pdf

http://www.semileds.com/system/files/MvpLED_Handling_and_Package_Notes_back_metal_Au.pdf

http://pt.slideshare.net/Alpha1Cookson/alpha-led-low-voiding-led-interconnects-english

http://www.osram-os.com/Graphics/XPic9/00063073_0.pdf/Details to the Assembly and Solder Pad Design of the OSLON, OSLON SSL and OSLON Square Family.pdf

Osram..."New lead-free solder materials, e.g. INNO solder (SAC solder with additives such as Ge, Bi) or IMS carriers with specially adapted dielectric strengths, offer further potential for improvement."

A lot of references to the importance of low voids , and fine grain of solder when concerning thermal control and long term reliability. It seems low temp Bi infused solder paste is a good match for hot plate reflowing, and actually recommended?

still deciding...I am leaning towards low temp now though. Seems it would better guarantee a thorough hotplate reflow.

Also came across stencils for xmls and a few other cree leds on one stencil. All you need to do is go to oshstencils.com and upload the file. It's only a few dollars per stencil.
https://oshpark.com/shared_projects/dw8NYoED

Found a downloadable osram stencil...http://ledlight.osram-os.com/led-ssl-tools/printed-circuit-board-designs/

before you can load it into osh stencil you need to unzip the file, open it in a free gerber file viewer, and save the stencil pad layer into a file you can locate. You can load that file into oshstencils.com

i wasn't able to modify the gerber file of the stencil with a free program so I couldn't set it up exactly how I wanted but it should work. Once they come in ill update on the fit and if it will work. $3 stencils...

the aluminum DIY stencil is quite amazing how it works but I'll try this affordable option first

Thanks for doing this leg work POS. So is the tin/bismuth stuff OK after all?

I don't want to say ok yet..sds is pretty up to date on this stuff.

sac305 seems to be a cost efficient, low void solder paste solution. Sn/bi low temp paste seems to be recommended by a few led companies but the chart sds linked to clearly states thermal fatigue.

sac305 is probably the safer choice when running leds hard. But for softer running led setups the low temp should work fine from what I've read.

One way to find out...Osions at max 1a with low temp solder and see how long they last. I'll let you know in a few months..lol.

Ill email chipquick and see what they think, that should help clear this up. They sell both types and I'm sure will recommend the most suitable.

Little progress

Stencil looks like a really nice fit. Even the extra frame option I added will come in handy. Just need to trim the frame for a tight fit on star, tape top of stencil in place, then tape on bottom (wear the adhesive out a bit so it doesn't stick too strongly). Then basically put star in frame and stencil should fall into place every time. More practical for larger numbers then lining each one up every time...it's a very precise fit on these tiny osram solder pads...couldn't imagine doing this without a stencil.

And the sinkpad stars are really nice, noticeably thicker than normal. Think I'll be reflowing all my single leds this way if it works out.

mmm sinkpad... but in aluminium... i like cooper mcpcbs of sinkpad...
stencil in plastic...ok i like ...

Hmmm..copper wasn't available in osram style. In the future I'll ask them about that...don't see why they couldn't do that..unless it needs to be a large order to do a custom run.

yes in cooper ....oslon no...yet

other thing is the osram solder pads ...i miss something like that...

Easy access temperature test point makes LED junction temperature measurements fast and simple.

...but for oslons pads... and a pad for thermistor on the thermal pad...

SR-02-thermal.pdf