REFLOW SOLDERING HOW TO VIDEOS: Stove eye and NOW Heat Gun.

I just thought I would share these with everyone, I've had a few of people ask about it. The video's aren't great as they are shot from a Sony Cybershot H10 digital camera (not really a video camera)

Here's the link to the Stove Eye Reflow

http://img694.imageshack.us/img694/5163/f6w.mp4


I was surfing the 'net today and came across a video on the Cutter site where they use hot air to reflow so me being the person I am :thinking:.......(in my head) "I have a heat gun.........and a spare XM-L laying around and nothing to do. :shakehead

Here's the link to the Heat Gun Reflow

http://img594.imageshack.us/img594/3482/15859166.mp4

The heat gun works faster than the stove eye IMO. Tested it for function after and it's good to go!

Hope this helps some of you,

Jamie

Thanks Jamie! Short, simple videos like yours will be helpful for those of us just getting started, so more videos like this of the various steps involved in an LED swap or P60 build would be much appreciated. Sometime this week, I'm going to try a reflow of the XPG you sent by using my Bernzomatic Micro Torch with hot air attachment. Like you demonstrated, I will use "Helping Hands", but I'm curious if heating from directly beneath the star would be effective and avoid possible damage to the LED if I were to use the torch above the board like you did with the heat gun. What do you think? Thanks!

I reflow XP-G's by heating the mcpcb from underneath.

Gene43 said:

I reflow XP-G's by heating the mcpcb from underneath.

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Thank you Gene! I'll try to check in this week to catch up.

Digikey has that video on youtube where they reflow solder an XR-E onto a MCPCB with a heat gun. It looks pretty easy. I guess you don't have to worry about ramping up the heat like it's shown in the data sheet of the LED?

The stove method has worked alright for me, but I'd like to try something that more consistent.

Here's the thread that has the YouTube video by Digikey. I used a butane stick lighter to reflow an SST-90 onto a 3/8" copper bar. Some SKU 7952 or 4711 reflow paste from DX did the trick. Store in the fridge in a ZipLock bag when done.

I saw another video where a guy used a regular toaster over to reflow an entire board. Probably has a greater degree of control than a stove or a torch. Just watch through the glass window. The 63/37 paste melts at 183°C. Most LED data sheets say T max for leaded solder is 215°C or 419°F for about 30 seconds. So that would be a maximum of 30 seconds after you see it melt.

I agree with Gene43 about heating from below. Especially if you use a torch. The optical silicone glue is only good up to about 450°F.

I couldn't see the videos earlier when I was at work, but you made it look easy, think2x. Reflowing them directly on the range is probably what I was doing wrong. That, and trying to follow the preheat/ramp-up procedure with a stove that won't regulate its temperature the same way twice.

Al Combs, thanks for the link. When you put the solder paste in the fridge, are you supposed to recap it every time you put it away or is it alright to leave the needle tip on there? It seemed messy to swap the tips so I haven't been doing that. Hope it doesn't dry out.

Look up zephpaste. The 63-37 no clean works very well for me.

The paste I bought from DX came in a little screw top plastic jar. I keep it in the fridge in a ZipLock bag with my Arctic Silver epoxy. I don't know the proper way to store the syringes of solder paste. A friend at work periodically gets syringes of reflow paste from Germany and he just leaves them on his desk. He says they last about a month without refrigeration. I asked him how he knows when it's gone bad or how it behaves. He said at some point the micronized lead particles just don't coalesce into a liquid anymore when heated. His best guess was the flux just dries out to the point it looses its wetting ability. The lead corrodes before it can melt.

If it is a matter of the flux drying out, I would imagine being in a open syringe would speed up that process. Even if it is stored in the fridge. Then of course there's the issue of possibly contaminating your food. If you have the original cap, that would have to be the best way to store it. You can always poke a piece of wire through the needle if it gets clogged from drying out.

Mike S said:

. . . . I guess you don't have to worry about ramping up the heat like it's shown in the data sheet of the LED? . . . .

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So why do you suppose Cree put those requirements in their datasheet ?

Gene43 said:

Look up zephpaste. The 63-37 no clean works very well for me.

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I just Googled your Zephpaste, 6 months without refrigeration is excellent. That was the other bad thing about the $3 stuff from DX, it's not a no clean type of paste. I used a Q-Tip and alcohol afterwards to clean off the residue.

I'm usually using the first methode with the stove and it works pretty well for me.

I place the MCPCB on the stove let it heat up. Then I put some solder on it and gently place the emitter on the board. I quickly adjust its postion and take it from the stove.

rayman

I use to use the Zephpaste and it worked well, just rather expensive.

I've since switched to Kester R276 which I can buy for about 1/3 the price (35g for the price of 12g of zephpaste). I store it in the fridge inside a ziplock bag.

The Kester performs as well or in my opinion better than the zephpaste.

If you do a lot of reflow, a temp/volume controlled hot air tool is a good thing to own. There are some on the market for <$100. For soldering LEDs on Stars a lot of heat is needed, and the stove works fine at the hobby level. I use an IR thermometer to monitor the electric stove element temperature and raise up the temp slowly.

Of course this is all hobby/prototype stuff - which is what we're discussing here.

And yes, the flux is what fails over time in the solder paste and you'll get clumping of the paste and it will not flow correctly when melting and you'll end up with lots of balls. With 'fresh' paste/flux when you reflow the solder paste just appears to magically flow together like some of the scenes of the T1000 from Terminator 2...

cheers,
george.

while reflowing don't ever touch the emitter dome - it can easily break without anyone ever notice it.

MikeAusC said:

So why do you suppose Cree put those requirements in their datasheet ?

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Well, I was asking because I've never used a heat gun and wasn't sure if it was capable of meeting the reflow guidelines in the datasheet. Cree states "... this general guideline may not apply to all PCB designs and configurations of reflow soldering equipment".

Mike S said:

Well, I was asking because I've never used a heat gun and wasn't sure if it was capable of meeting the reflow guidelines in the datasheet. Cree states "... this general guideline may not apply to all PCB designs and configurations of reflow soldering equipment".

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The thermal reflow profile is a recommendation by the manufacturer. It also allows the assembly house to determine if there is something special about a certain component that would prevent it from being reflowed along with out components. Most modern parts have a very similar reflow recommendation - otherwise imagine trying to assemble a board that has many components if each wanted a different profile...

Most of the profile requirements are to ensure that the solder paste flux performs correctly, that the solder paste flows correctly and balls are minimized, that the components aren't heated too quickly or cooled too quickly leading to thermal shock/stress that can damage the component immediately or long term. Peak temperatures ensure that the components aren't overheated.

You'll also find many components have their own requirements regarding humidity. Many are shipped in sealed bags with desiccant packets and moisture warning cards. If the components are left out for too long or the warning cards have changed colour, the components need to be baked for a certain number of hours and a certain temperature prior to the reflow process. This is to prevent damage to the component - especially where moisture could creep between the leads and the plastic package.

Obviously most of these recommendations and guidelines are aimed at production processes where reliability (short term AND long term) is critical for mass produced products.

For hobby level stuff, anything goes as long as it lasts long enough to be obsoleted by the next latest & greatest LED etc etc...

cheers,
george.

Do you think an electric counter top burner such as this would work? If so then I could avoid damage to my home stove by using it.

bla2000 said:

Do you think an electric counter top burner such as this would work? If so then I could avoid damage to my home stove by using it.

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I believe so, I was actually going to buy one of those just for reflowing so I could stay out of the kitchen. :thumbsup:

Gene43 said:

I reflow XP-G's by heating the mcpcb from underneath.

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Yes, thank you Gene. I usually heat from the bottom too but after seeing the video on cutter I just wanted to try it, no damage and it works just as it should. I will heat from the bottom on the rest of them.