Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > General Electronics Technical Discussion
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 04-27-2019, 03:11 PM   #21
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 3,974
Default 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.
diif is online now   Reply With Quote
Old 05-04-2019, 05:54 PM   #22
momaka
Badcaps Veteran
 
momaka's Avatar
 
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 8,935
Default Re: Reballing discussion and tips

Quote:
Originally Posted by diif View Post
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.)

Quote:
Originally Posted by Dannyx View Post
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.)

Last edited by momaka; 05-04-2019 at 06:13 PM..
momaka is offline   Reply With Quote
Old 05-05-2019, 07:43 AM   #23
Dannyx
CertifiedAxhole
 
Dannyx's Avatar
 
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 2,370
Thumbs up Re: Reballing discussion and tips

Quote:
Originally Posted by momaka View Post
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
__________________
Wattevah...
Dannyx is offline   Reply With Quote
Old 05-05-2019, 07:28 PM   #24
momaka
Badcaps Veteran
 
momaka's Avatar
 
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 8,935
Default Re: Reballing discussion and tips

Quote:
Originally Posted by Dannyx View Post
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
momaka is offline   Reply With Quote
Old 05-05-2019, 10:30 PM   #25
Dannyx
CertifiedAxhole
 
Dannyx's Avatar
 
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 2,370
Default 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 is offline   Reply With Quote
Old 06-11-2019, 05:15 AM   #26
Dannyx
CertifiedAxhole
 
Dannyx's Avatar
 
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 2,370
Default 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
Dannyx is offline   Reply With Quote
Old 06-11-2019, 07:50 PM   #27
diif
Badcaps Veteran
 
Join Date: Feb 2014
City & State: Midlands
My Country: England
I'm a: Professional Tech
Posts: 3,974
Default 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.
diif is online now   Reply With Quote
Old 06-11-2019, 10:50 PM   #28
Dannyx
CertifiedAxhole
 
Dannyx's Avatar
 
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 2,370
Default Re: Reballing discussion and tips

Quote:
Originally Posted by diif View Post
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
Dannyx is offline   Reply With Quote
Old 06-15-2019, 06:50 PM   #29
momaka
Badcaps Veteran
 
momaka's Avatar
 
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 8,935
Default Re: Reballing discussion and tips

Quote:
Originally Posted by Dannyx View Post
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.
momaka is offline   Reply With Quote
Old 06-16-2019, 01:55 AM   #30
Dannyx
CertifiedAxhole
 
Dannyx's Avatar
 
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 2,370
Talking Re: Reballing discussion and tips

Quote:
Originally Posted by momaka View Post
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 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2019
Powered by vBulletin ®
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 02:17 AM.
Did you find this forum helpful?