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Toaster Oven Reflow Soldering (BGA)

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Doing solder reflow work can be expensive and difficult, but thankfully there exists a simple and elegant solution: Toaster Ovens. This project shows my preferred setup and the tricks that make the process run smooth. In this example I'll focus on doing reflow of a BGA (ball grid array).
 
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Step 1: Find a toaster oven.

You're looking for two main things, an adjustable temperature knob, and a timer that will time down. The more precision you can get in the timer the better.

Also, if you can get it, some sort of forced air flow will improve the uniformity of the oven temperature, but you have to make sure that the air flow isn't powerful enough to move your components around.

Step 2: Get a thermometer and timer.

Even though the toaster oven has a temperature set point and an integrated timer, you still want to get some more accuracte readings. Get a cheap oven thermometer and toss it inside the oven and get a timer with an alarm to remind you to check on your baking PCBs.

Step 3: Make your PCBs.

In this exampe I'm working with an ADXRS300 which is a 1 axis Gyrometer made by Analog Devices. It comes in a ball grid array package with the balls already attached to the bottom of the component. The PCB needs to be designed with pads for each of the balls, along with a silk screened outline to make it easy to align the component (which is critical when you can't actually see the pads). Also, duh, make sure you mark the location of Pin 1.

Step 4: Add flux to the PCB.

The balls in the BGA don't have flux so you *absolutely* have to put down flux on the board prior to doing the reflow. If you don't add flux then the oxide on the top of the pads will keep the balls from flowing and you'll end up with slightly squished balls that are not actually connected to the underlying PCB.
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49percentGood8 months ago
You say,

"...you still want to get some more accurate readings. Get a cheap oven thermometer and toss it inside the oven..."

No. Do not do this! Think about it. You're putting a cheap thermometer in the oven to get,

"...some more accurate readings."

This makes absolutely no sense and might very well be setting you more off track than using the default toaster oven thermometer & timer.

Cheap doesn't mean low quality or worse accuracy, cheap means less money. If for 0.0001 degree more accuracy you have to pay 1000 more times you don't need, it doesn't mean that 0.1º being much cheaper is worse. For reflowing 0.1º doesn't matter really, but for eye surgery it does. Anyway since we don't know the characteristics of both thermometers, we can't guess anything.

Surely the a nice solution in this case is locate the built-in temp probe and move it to a better place.

patil.ameya6 months ago

"You should make sure that all of the balls are connected and that the component is strongly attached to the PCB". How to check for the connections of the balls of the BGA ic?

AMB_21 year ago
For the temperature control you can improve your oven by adding a PID controller. I you are not familiar with them you can use the ones specially designed to transform domestic ovens in n_electronics (www.nelectronics.org), adafruit (www.adafruit.com) or drotek (www.drotek.fr).
Like that you will be able to achieve nice soldering profiles without the need of a external timer and the risk of damaging the components is much lower.
N.fletch1 year ago
Awesome! I was afraid I wouldn't be able to use a FPGA BGA chip and I would have to resort to the less robust: quad flat pack version. Thanks!
pyper2 years ago
When doing SMD stuff at work I tend to use "tacky" flux which comes as a gel. It not only serves as a flux but makes positioning IC's a lot easier as you can sit them on top of a little blob of it and then fine tune their position with your tweezers (aligning TSSOP48's would be pretty much impossible without it IMHO) It also helps stop things getting blown about in the oven too!
hellstudios4 years ago
hey, although this worked with my laptop's video card awhile ago, i just tried it with a desktop motherboard at the temperatures you specified and it melted the plastic and caused one of the capacitors to explode... ruining a perfectly good motherboard that just needed a simple fix. :(

I looked further into reflow and other resources say that the temperature should be between 390F to 420F. NOT 450F. please edit your instructable so other people don't make the same mistake i did.

also, try not the breathe the smoke in that is released from the motherboard, I accidentally did and now I feel light headed.
Valuable life lesson here if you can forgive yourself for damaging your board. Always seek out more than 1 source of information.

The author's example is building a BARE PCB up with no mention of plastic.
The author could not anticipate that someone would try to reflow plastic parts, or inhale the fumes. You can not document common sense in the space of a tutorial.

Since you wanted to reflow a populated board, I would have sought one of those tutorials out (there's lots of them, particularly for the x-box, as reflowing the board is something many customers have needed to do).

By the way, your motherboard was not ruined. Capacitor replacement is one of the easier repairs to make. $3 on ebay would get you a replacement cap of the right size, and you could solder it back in with a cheap iron.

I'll also throw in, if you want to do localized reflow without heating the whole board, a heatshrink gun can work (Sparkfun has a Heaterizer 2000 for like $10). You can still make mistakes of course...

If the part is valuable and you are a novice, best to watch someone else do it the first time (youtube is good for this!)

Indeed.

it was a crappy little socket 478 mobo anyway, Yes, lesson learned, atleast i didn't do it to a more expensive component.
A cheap screw up then. :D

Reflowing "smt" chips, resistors, caps, or any other "surface mount" components on a motherboard is the FIRST process they do to it.. BEFORE adding the other components that are "heat sensitive".. ie: "melt at high heat". The plastic based components are added later.. by hand.

Think of it this way.. would you allow your motherboard to run at 390F - 450F? No. Reason is, those plastic components will fry.

There's nothing wrong with this method. Many use their bigger ovens as well. You just need to be sure you are familiar with electronics before you attempt to do something like this.

If you need something directed at a single component on the board, then look for the instructables called "DIY Hot Air Soldering Iron". A "reflow pen" is what you need. More control of where the heat is applied. ;)



Chhers.......................
some people have used butane jet lighter style torches to reflow components with high levels of success, i tried and had i not accidentally pulled off some pads (because i didnt wait) the palm pilot would have worked fine again.

people have used these torches for laptops more specifically, since most people arent smart enough to try it ont eh desktops, since they figure motherboards are eas to replace anyways.
Lead-free solder has a higher melting temperature. 420F/215C is peak temperature for lead bearing solder which is ban after year 2002, Lead-free solder has peak temperature of 450F/232C for 1 min or 425F/217C for 3 min..... Never reflow PID's and plastic parts in IR oven together with SMD's without covering them with kapton tape.
By IR you mean infrared? I was using a normal kitchen oven with the mobo suspended on tinfoil cubes.
evanwehrer6 years ago
Check this out: http://www.sparkfun.com/commerce/product_info.php?products_id=81
Toaster oven Reflow Controller
I have nothing to do with sparkfun but I think its a really cool kit.
and...you program it yourself. and sparkfun's toaster oven works better than their reflow oven :P
5150tech4 years ago
Nice job. I have done thousands of BGA profiles professionally and I like how this boils it down to the basics time and temp.  the only thing I would do is rewire the oven so both elements run together so you soak through the component. I think that will get everything up to 183c (for lead solder and 205-230c lead free solder) pretty quick. on the other hand, if it's not broke don't fix it.
vxir4 years ago
How do you make sure that all the balls are connected?  Won't the body of the chip block any inspection?
lilimike4 years ago
What about the solder?
Did you add solder to the pads?
Will any kind of solder do the job?
Macka lilimike4 years ago
I believe the balls on the chip are balls of solder that are preplaced, so no further solder is necessary.
CCronaldo4 years ago
Do you know where to buy solder paste and how to apply it if it is not a reflow, but a first time application? I like your instructable, it is well done.
-----------------------------------------
quang cao online | quang cao
Earths_hope4 years ago
Wow! It's amazing what you can find in what would be useless little electronics!
beneaton7 years ago
For an even simpler approach take a look at http://www.reconnsworld.com/griddle_reflow.html.
(removed by author or community request)
I thought so, too. Just remove the last period after you click the link and try again. The period got captured by the link formatter.
bucklipe4 years ago
What about an external motor with the fan shaft going through the bottom(?) with a speed regulator. This way the fan blades could be aluminum and large enough to move the air slowly. With the motor mounted outside the limiting factor would be the melting point of aluminum, not a factor with the temps used for solder.
ZBM6 years ago
question : for a forced airflow would two holes cut in one at say the top left and at the bottom right with a PC fan attached at one of the holes work?
dUc0N ZBM6 years ago
I can understand where you're going with that, but it'd probably hurt more than help, as the fan would be pulling cooler air from the room into the oven, and then forcing nice hot air out the top. A better solution (if you want to mod it yourself) would be to come up with a fan that can withstand the temps you intend to use the oven at (plus a good safety margin, an additional 10-20% or so), installed on the inside of the oven. The best positioning would probably be right at the top, aimed down, where it'd suck the hottest air from the top and channel it directly onto the part you're working with.
sparr dUc0N4 years ago
I want to stress that the airflow should be *VERY* slow. You are not trying to bring more air in contact with the part (which is what small fans normally do, like on heat sinks). You are just trying to even out the temperature of the air, like a ceiling fan.

Imagine a computer case fan spinning at 100RPM instead of 2000RPM. Except a computer case fan would melt in a toaster oven, but you get the idea.
ZBM dUc0N6 years ago
thanks for the input
colin (author)  dUc0N6 years ago
Actually, you probably want to avoid blasting the air straight onto your board. There's nothing worse than having components slide around when the solder is molten. That being said, a gentle breeze should be fine.
dUc0N colin6 years ago
Point taken, especially considering the fact that you're the experienced one. =-)
cjeung5 years ago
I've got a video card with a faulty connection in it's bga connection. Using this fine instructable, I have a question. Will I have to completely remove the chip, to rework solder, or can I just toast board and hopefully the faulty connect will reflow? In other words, do I have to remove chip because I'll need to apply flux?
sparr cjeung4 years ago
If you try to toast the board, there's a chance you will damage other components that were added after the original soldering step. I would not advise it, but if you are determined to try then remove everything that can be removed (esp plastic parts and stickers and sticker-residue!) beforehand.
cjeung5 years ago
Zounds! This was an excellent tip. Saved myself beucoup dinero on a laptop repair. Thanks aplenty!
I just received a bunch of FPGAs with BGA type package, so this'll come in handy. Thanks for the info!
Such a cool idea.
Sandisk1duo5 years ago
what were you using the Gyrometer for?
drsoubhi6 years ago
Dear Mr. Colin

Hi,

I have an old Minolta Dimage 7 Digital Camera.

I think that the BGA Processor has some cold welding.
Is it possible to use your procedure to reflow the affected AGP pins?

Also you didn't mention the duration needed for that operation.

I'm a dentist, and I prefer to use a ceramic electronic oven which is more accurate and it's available in any good Dental Lab.

You can read my trouble by visiting the following link:

http://forums.steves-digicams.com/forums/view_topic.php?id=587881&forum_id=20&jump_to=866089#p866089

Please help me regarding this issue.

Soubhi Sabbagh
email: lego(at)aloola.sy
GSM +963944416832

bluntknife6 years ago
Sorry I'm very new to this and have a newbie question. Once you have 'dabbed' the solder paste onto the components legs where do you apply the flux? Do you smear it all over the pcb area where the surface mount component will be connected or do you have to precisely apply the flux to each of the legs too? Thanks.
robomaniac6 years ago
He is building a Quatrocopter!
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