Reballing discussion and tips

[diif]

Re: Reballing discussion and tips

It's not about grunt but the different methods they use to cook. A sandwich maker cooks by conduction whereas a roaster oven used convection.

[momaka]

Re: Reballing discussion and tips

It's not about grunt but the different methods they use to cook. A sandwich maker cooks by conduction whereas a roaster oven used convection.

Exactly!

Although with the sandwich maker, heat is actually mostly transfered by radiation. Same goes for any station that uses IR heating.

With heat guns, hot air stations, and the natural gas / propane burner method I suggested above, heat is transfered pretty much entirely by convection. Again, it's not very efficient, but it produces more even heating.

A toaster is a bit of both, with the heating elements emitting both IR and producing hot air around them (that rises and heats the board). So you get a bit of both worlds in there.

But again, I myself prefer mostly some type of hot air convection method. IR tends to bounce and scatter from light and shiny objects and that can lead to different heating rates.

And conduction is what your soldering iron uses (i.e. heat conducts from the hot tip directly to the component's leads.)

So you're saying a sandwich maker or other devices with heating elements don't have enough grunt when assembled as originally intended by the factory and I'd need to get closer to the heat source.

Well, it's not so much power, but rather power per surface area. 500W into a, say, 50x50 mm plate (2500 mm^2) will get a lot hotter than same power into a 100x100 mm plate (10000 mm^2 - i.e. 4 times the surface area.)

It also depends a lot on the heating element type - i.e. exposed Nichrome wire (what hot air stations and toasters use, for example) vs. ceramic plate with embedded Nichrome (your typical IR machine) vs. heating "rods" (the type of heating elements you see in your kitchen's oven).

When you say sandwich maker, I imagine those "sandwich presses" / waffle presses (that have heating surfaces on both sides and you close like a chest). If that's what you're talking about, then those probably won't work, because they generally have a heating element (either a "rod" or Nichrome wire) embedded into an aluminum frame or ceramic surface... which in itself isn't that bad. But these things are generally in the ~500W range or less, and so the surface area is too large to get hot enough for that power level.

Now, if you're talking about one of those "mini ovens" (also sometimes called sandwich makers... go figure )... MAYBE you can make something that works. But again, it will depend on the heating element types used inside. If heating "rods", it probably will work OK for a "general" bottom heater (might not have enough power for larger boards and also might not produce very even heating.)

[Dannyx]

Re: Reballing discussion and tips

When you say sandwich maker, I imagine those "sandwich presses" / waffle presses (that have heating surfaces on both sides and you close like a chest). If that's what you're talking about, then those probably won't work, because they generally have a heating element (either a "rod" or Nichrome wire) embedded into an aluminum frame or ceramic surface... which in itself isn't that bad. But these things are generally in the ~500W range or less, and so the surface area is too large to get hot enough for that power level.

Yes, that's what I picture whenever I hear "sandwich maker" - a "press", as they call it. Indeed, those certainly won't do, since they don't get near hot enough to melt solder...though now that I think about it, its purpose as a "heater plate" would be to just get the board hot but not to the point where it's starting to melt solder by ITSELF - that would be a disaster as it would cause SMDs to fall off, so in the long run it could actually work as a poor man's version of a heater plate

[momaka]

Re: Reballing discussion and tips

Indeed, those certainly won't do, since they don't get near hot enough to melt solder...though now that I think about it, its purpose as a "heater plate" would be to just get the board hot but not to the point where it's starting to melt solder by ITSELF - that would be a disaster as it would cause SMDs to fall off, so in the long run it could actually work as a poor man's version of a heater plate

No, heating a board above the solder's melting point will NOT cause SMD components to fall off. The reason why is because SMD components are actually glued to the PCB before being brushed with flux/solder paste and put through the wave soldering machine. Otherwise, how else would you expect them to stay there and not fall off when they go through the wave soldering machine? And even non-glued components like small-to-medium sized BGA chips will not fall off. That's because solder is similar in this regard to water: it has adhesion properties - i.e. once it's stuck on "something it likes" (that is, metal that wicks to solder or other solder), it won't let go so easily (even in liquid state). Ever wonder how video cards and boards with RAM chips on both side of the board don't fall off?

Anyways, here's also an interesting video on how PC boards are made:
https://www.youtube.com/watch?v=cZOe4VDHn8Y

[Dannyx]

Re: Reballing discussion and tips

True, I just realized that after writing.....and I have been soldering for some years now and often use that surface tension of the solder to get stuff to "snap" into place, so I don't know what I was talking about

Still, the plate should not be red hot I imagine...just enough to get the temp in the ballpark before attacking the top with the iron or hot air.

[Dannyx]

Re: Reballing discussion and tips

Just thought of something, even though's not industry standard and would probably not work/last: what if instead of solder balls or paste, you just ran a blob of regular "reel" solder over the chip covered with flux with the hot iron like when tinning SOIC pads or something larger like that ? The solder would stick to the pads and there's your balls

[diif]

Re: Reballing discussion and tips

When was the last time you soldered a pad and instead of it being tinned there was a nice 0.5mm solder ball? Now repeat that 500+ times for all the other pads.

[Dannyx]

Re: Reballing discussion and tips

When was the last time you soldered a pad and instead of it being tinned there was a nice 0.5mm solder ball? Now repeat that 500+ times for all the other pads.

That seems to happen when I haven't got enough flux, so I learned how to work around it the more I soldered. True, the pads on a chip can get ridiculously small so the chances of the solder blobbing up increases. I might try it one day actually - practice makes perfect

[momaka]

Re: Reballing discussion and tips

Just thought of something, even though's not industry standard and would probably not work/last: what if instead of solder balls or paste, you just ran a blob of regular "reel" solder over the chip covered with flux with the hot iron like when tinning SOIC pads or something larger like that ? The solder would stick to the pads and there's your balls

I've actually tried that before. The chip will solder to the board, but very unreliably / not all contacts in most cases.

Reason why is as diff mentioned - you're not going to get nice balls on the pads, but simply "bumps" of soldered. And even if you try your best, those solder bumps will not be the same... or even that similar, even if it looks like it to your eye. This means that while some of them will solder fine to the board pads, others might not reach it at all or would be under-soldered. Add the fact that the board will always flex when re-heating it to high temperatures, and you can be assured that more than likely not all pads will be soldered.

But I went a step further (without thinking): on the second try, I tinned (i.e. put solder "bumps") on both the board and the BGA chip itself... only to realize that there is no way to place the chip on the board, as the round solder bumps on both would make the chip slide off to one side. So in the end, it was impossible to position the chip properly this way.

So all in all... no, this likely won't work. I tried it many years ago at that repair shop I used to work at, where I had access to a decent IR station. I didn't work then, so I don't think it would work now either. But give it a try if you're really curious. Sometimes that's the best way to satisfy a curiosity and learn things.

[Dannyx]

Re: Reballing discussion and tips

But give it a try if you're really curious. Sometimes that's the best way to satisfy a curiosity and learn things.

No, you've actually saved me a lot of time, effort and frustration...plus I don't have access to the BGA machine anyway...only the old folks at this place do, I mean why give others a chance, right ? >_> One day, justice shall be served !

[Dannyx]

Re: Reballing discussion and tips

Back on the topic of reballing: should you cover up the various plastic parts on the board like RAM slots and CPU sockets before hitting it with IR ? Like I said, G who handles reballing around here, covers up the area around the chip with aluminium tape, which I wouldn't personally do, but it does seem like a good idea to do this with plastic elements.

[diif]

Re: Reballing discussion and tips

Back on the topic of reballing: should you cover up the various plastic parts on the board like RAM slots and CPU sockets before hitting it with IR ? Like I said, G who handles reballing around here, covers up the area around the chip with aluminium tape, which I wouldn't personally do, but it does seem like a good idea to do this with plastic elements.

Don't use the adhesive on the aluminium tape, heat makes it a sticky mess. Aluminium foil or aluminium tape stuck down with kaption tape.
I only cover anything plastic if it's directly next to the IC I'm reflowing.

[Dannyx]

Re: Reballing discussion and tips

Hmmm....his doesn't seem to leave any gunk behind. Either that, or he simply doesn't clean it afterwards

EDIT: I learned a while back that we have a second T890 reballing machine around here that's dead. Apparently its "lamp" died. Not having looked into these things before and not actually seeing the device itself up close, I had no idea what this "lamp" truly is or what it looks like. I know it's the "head" that actually heats up the board from above, but had no idea what the active element inside it is, that is until I looked it up on Ali and found THIS....looks like a heating element. How is that an IR "lamp" exactly ? Could be a mistranslation after all Not only that, if that's the only thing wrong with that machine, for 20 odd dollars I could make myself a functional BGA machine...

[diif]

Re: Reballing discussion and tips

It is a heating element. If it gives off IR radiation it's an IR heater.
I doubt it's 1500W more like 300W. The IR rework station is 1200W for the bottom, 300W for the top.
If you can get one of these in the housing https://www.aliexpress.com/item/32522148095.html it would be even cheaper.
It's 450W not 300W so you might need to modify your machine.

A real reballing machine. https://www.youtube.com/watch?v=JH4HKQoSyps

[Dannyx]

Re: Reballing discussion and tips

With everybody gone from the shop during lunch break, I sneaked around to where I know the dead machine lies to have a look at it and snap some pics for later use I shouldn't have to do this - I friggin' WORK here - it's like I'm thief around here Unfortunately this might be a bit more of a hassle to restore than I expected - the head has a couple of other loose parts dangling around inside, so it's not as easy as bolting in the replacement element - these guys may be clueless half the time, to the point where I'm screaming internally, but even they are not SUCH blockheads to not have thought about replacing the heater. A new head assembly is too expensive for me to purchase on my own. From what I understand, they thought about replacing the whole head assy like that, but for some reason chose to replace the entire machine because they claim the price difference between the two was too small to warrant replacing the head: around 200$ vs. 400$....not that small a difference, but anyway....

A real reballing machine. https://www.youtube.com/watch?v=JH4HKQoSyps

Actually my wildest tech fetishes pictured something just like that a while ago (hell, even before I went into the field ), but I never thought it existed until I eventually looked it up, further confirmed by your video now: a machine which replaces the shaky human hand by having a head which can carry all sorts of tools on it and uses them with pinpoint accuracy like that: soldering, wicking, fluxing, balls, you name it. After all, there's no reason why it CAN'T exist: it's just a slightly more advanced CNC in the long run....turns out it DOES exist (and I was certain it did, but only in highly professional environments). I'm sure our shop could afford something like that - it's a HUGE business - but it would take years to pay for itself due to the relatively low prices one can charge for a reball operation.

[diif]

Re: Reballing discussion and tips

Here's a far better quality video.
https://www.retronix.com/services/bga-reballing/

[Dannyx]

Re: Reballing discussion and tips

Here's a far better quality video.
https://www.retronix.com/services/bga-reballing/

Oh yeah, that's some quality porno right there ! ! In all seriousness, I'm curious how much one of those would cost

[stj]

Re: Reballing discussion and tips

so you buy a heater, then find the ssr was bad?

[Dannyx]

Re: Reballing discussion and tips

What's a SSR ?

Whatever it is, hence another reason why they chose to replace the whole machine. Truth be told, this place has MANY other basic things lacking before it can consider going pro with reballing stuff >_>

[stj]

Re: Reballing discussion and tips

SolidState Relay.

usually a block with 4 screw terminals and an led on it.