Start back at square 1. How did you determine that this chip was bad? Did you use a heat imager (TIC) to see a short on this chip? At I stated before, it is possible that a solid short may have welded this IC to the board and NO amount of heat will release it. You can try using a soldering iron (Weller gun type) with the tip directly on the chip. This will apply heat only to the chip. If this also fails, this board can be marked as unrepairable.

-Dan

The chip must be replaced, that's out of the question and not really the topic, long story short, it's a software problem, not a hardware issue. The chip should be soldered correctly just like any other chip in the board, no shorts, not corrosion, nothing weird.

I might try tomorrow again with the below gun at 200ºC, or finally what you said, my biggest top and a blob of solder right on top. I didn't know I could do that TBH, I might practice first on other boards to remove chips SMD like that (I know they must be small enough so the top covers most of the area).

 

The chip must be replaced, that's out of the question and not really the topic, long story short, it's a software problem, not a hardware issue. The chip should be soldered correctly just like any other chip in the board, no shorts, not corrosion, nothing weird.

I might try tomorrow again with the below gun at 200ºC, or finally what you said, my biggest top and a blob of solder right on top. I didn't know I could do that TBH, I might practice first on other boards to remove chips SMD like that (I know they must be small enough so the top covers most of the area).

If board was hot to touch , it was under 50 degrees , you the whole board to be up over 100,
If board was only warm to touch , it's not hot enough. .
The chip board design is such it moves heat fast. . if the board is only warm , then there is still lots of ability of chip to dissipate your heat. .
Solder melts under 200, you don't need 800 degrees , it's not a sprint ..

 

If board was hot to touch , it was under 50 degrees , you the whole board to be up over 100,
If board was only warm to touch , it's not hot enough. .
The chip board design is such it moves heat fast. . if the board is only warm , then there is still lots of ability of chip to dissipate your heat. .
Solder melts under 200, you don't need 800 degrees , it's not a sprint ..

Maybe I need to set the below heat gun to 250ºC so the area and arounds (and whole board overtime) gets to 150ºC or so... I was thinking that was another option, but I don't know, I practiced on other boards with similar sized chips and I could totally remove them without preheating or anything... maybe this board and those alike really need to be extremely hot (150º whole thing) to really have a chance.

Anyways, as you can see in the video, the guy performing this removal doesn't preheat the board, it's just flux and heat on it for a few minutes.

 

Anyways, as you can see in the video, the guy performing this removal doesn't preheat the board, it's just flux and heat on it for a few minutes.

No. I just watched the video. He heats it from few minutes and it does not come off. Then the video cuts to showing the chip after removal. We have no idea what he did to get it off, or whether he actually did so.

 

Maybe I need to set the below heat gun to 250ºC so the area and arounds (and whole board overtime) gets to 150ºC or so... I was thinking that was another option, but I don't know, I practiced on other boards with similar sized chips and I could totally remove them without preheating or anything... maybe this board and those alike really need to be extremely hot (150º whole thing) to really have a chance.

Anyways, as you can see in the video, the guy performing this removal doesn't preheat the board, it's just flux and heat on it for a few minutes.

What video ?

 

hi,
Post #1, video.
E

 

hi,
Post #1, video.
E

Ta, couldn't remember that far back..

 

@rambomhtri
In addition to what Bob says .
Notice that is a much smaller chip, with pins, and no heat pad,
The chip you show has no pins is much bigger and has a large heat disipator.
The small chip, is going to be effectively thermal isolated from the boad, your chip has a large heat spreader that is going to be intimate with the power planes on the board, and designed to get heat away.
It's like saying a Fiat 500 is the same as a Bradley tank as they both move !
Also, re the video,
I guess your referring to this as an expert ?
Notice, they have no end straps on wrist, no anti static mat under board, and they even slide a static inducing board under the board at various tines.
If we saw any of that in our re work stations, the person would be sacked !

 

Hello!

I finally removed it, apparently nicely, without breaking anything. The trick was to put the heat gun below to 250ºC for 15 min or so, first time I had it at 150ºC, and then attack the chip from above with the SMD heat gun at 450ºC. It went smooth and fine, and the aluminum foil really worked 100% perfect protecting every other component from heat or accidental desoldering.

HOWEVER, I failed at soldering the new chip... first, I cleaned the old solder, put a fresh new one with Pb on the pads, just a bit, and then soldered the chip. It went smooth, I pushed the chip a bit and it came back to its correct position, meaning the melted solder was working as expected, but when I assembled the laptop again, it would not boot up.

The other chip was able to boot, no problems.

So I thought "maybe some pads are not making contact at all". You know, I hate this SMD soldering stuff, it's impossible to check if all the pads are perfectly connected without any short circuit or open circuit. It was my first, but again, I hate that you can't see anything, it's absurd to replace these chips. I don't know how people solder CPUs and memory chips with 100s of balls and pads, what the heck...

I tried the heat gun again, wiggle a bit the chip, it was apparently floating nicely, I didn't put too much, if anything, I was worried I put so little solder.

Desperate, I used my soldering iron to touch the pads from the outside. This was my mistake: doing this, I accidentally removed 2 tiny components, resistors or caps, really tiny, next to the chip, and lost them. So now it's done... I am sad.

This was my first SMD soldering experience, at least the first one that was actually meant to fix some expensive board (it costs 150€ new). I am happy I was able to remove the chip without apparently damaging anything, but I knew I would hate with all my soul this kind of soldering where you can't see anything to check for open or short circuits. Hate it.

 

Hello!

I finally removed it, apparently nicely, without breaking anything. The trick was to put the heat gun below to 250ºC for 15 min or so, first time I had it at 150ºC, and then attack the chip from above with the SMD heat gun at 450ºC. It went smooth and fine, and the aluminum foil really worked 100% perfect protecting every other component from heat or accidental desoldering.

HOWEVER, I failed at soldering the new chip... first, I cleaned the old solder, put a fresh new one with Pb on the pads, just a bit, and then soldered the chip. It went smooth, I pushed the chip a bit and it came back to its correct position, meaning the melted solder was working as expected, but when I assembled the laptop again, it would not boot up.

The other chip was able to boot, no problems.

So I thought "maybe some pads are not making contact at all". You know, I hate this SMD soldering stuff, it's impossible to check if all the pads are perfectly connected without any short circuit or open circuit. It was my first, but again, I hate that you can't see anything, it's absurd to replace these chips. I don't know how people solder CPUs and memory chips with 100s of balls and pads, what the heck...

I tried the heat gun again, wiggle a bit the chip, it was apparently floating nicely, I didn't put too much, if anything, I was worried I put so little solder.

Desperate, I used my soldering iron to touch the pads from the outside. This was my mistake: doing this, I accidentally removed 2 tiny components, resistors or caps, really tiny, next to the chip, and lost them. So now it's done... I am sad.

This was my first SMD soldering experience, at least the first one that was actually meant to fix some expensive board (it costs 150€ new). I am happy I was able to remove the chip without apparently damaging anything, but I knew I would hate with all my soul this kind of soldering where you can't see anything to check for open or short circuits. Hate it.

Four possibilities ..
All that excess heat too quick from earlier attempts broke vias in the board
All that excess heat broke / shorted out other component
It was not that chip
That chip going took out something else like a track.
Re smd, yes you do need the right tools and techniques to work it reliably
It's like asking a plumber who uses a flame , to the electrician who uses a temperature controlled iron. Both are connecting copper with heat and solder , but I know which I would want to look at a broken board.
As for replacing the chip, again it's slow and easy , slowly warm the board up to avoid tracks / vias being broken by thermal shock. Use a stencil to apply the right amount of solder paste, place and warm up using the soldering profile as per the chips data sheet. Basically slowly up and slow down .
Thanks for the feedback , and with some more practice and the right tools you will get it .
,0204 are very common components , most is soldered using stereo microscope and good magnifying lights.

 

I hardly believe I damaged the board with the heat, there was nothing burnt or different colored, and check the pic, the foil was protecting everything nicely. Only showing the chip. The chip was bad, 100%, out of the question, it was software, not hardware. Even if the chip was not the problem (which is false, but lets assume), I did something wrong later as the board was not booting up anymore.
I don't think I broke any other component, and the pads below the chip I desoldered were nice and shiny, I know how a damaged track looks like, or one that has been ripped off due to mechanical force when solder was not melted yet.

I'm 85% sure I simply didn't solder all the pads to the board of the new chip due to not enough solder, and then I messed up sweeping away 2 tiny components next to the chip when I was reworking with the iron.

 

I hardly believe I damaged the board with the heat, there was nothing burnt or different colored, and check the pic, the foil was protecting everything nicely. Only showing the chip. The chip was bad, 100%, out of the question, it was software, not hardware. Even if the chip was not the problem (which is false, but lets assume), I did something wrong later as the board was not booting up anymore.
I don't think I broke any other component, and the pads below the chip I desoldered were nice and shiny, I know how a damaged track looks like, or one that has been ripped off due to mechanical force when solder was not melted yet.

I'm 85% sure I simply didn't solder all the pads to the board of the new chip due to not enough solder, and then I messed up sweeping away 2 tiny components next to the chip when I was reworking with the iron.

As ever then , your the expert on internal vias and how they react to sudden excessive heat.
All those technicians who do it the slow w way must be wrong.
Best of luck .