Replacing laptop EC without hot air station.

[SuperGiachi]

Hi all, i finally have some spare time to try to repair my ASUS laptop with a blown Embedded Controller IC (about 64 pins, it is an ITE IT8585E). The problem is that i don't have a hot air station. I have already tried to desolder i with my soldering station but i can't heat all 4 sides simultaneosly. I was thinking about running a copper wire underneath the pins, winding it around the iron and using the iron as a heat source. The problem is that i don't know if the wire will get hot enough to melt the solder in all four sides(the wire has to be very thin otherwise it won't go underneath the pins). Will this solution be harmful to the solder pads or can I give it a try? As a last resort I would cut the pins with a cutter and hope not to scratch anything. What should I do?
Thanks in advance.

[wraper]

You could use low melting point alloy like wood's metal or chipquick. Or just cut off IC terminals and then remove them with soldering iron. Just be wary to not apply mechanical stress of the pads because of the danger of lifting them.

[JFJ]

Unless you have very fine, high precision, side cutters, low melting point solder may be the safer option.

Dave did a video review of ChipQuick:

[SuperGiachi]

Wound such an alloy mix with the rugualar solder and lower the overall melting point?

[tsman]

Wound such an alloy mix with the rugualar solder and lower the overall melting point?

Yes. That is what ChipQuik is sold for. Watch the linked video. Once you've removed the chip, you need to clean all the alloy off the board before putting on the new chip with regular solder.

[SuperGiachi]

I just watched the video and realized that he explained that in the beginning . Thanksguys for your advices, I'll try this chip quik.

[SuperGiachi]

One last question: Is there a chance that the solder pads got weakened by the fact that i melted some regular solder over the pins while trying to get it off?

[Terry01]

One last question: Is there a chance that the solder pads got weakened by the fact that i melted some regular solder over the pins while trying to get it off?

So long as you didn't put too much heat into them for extended time or were too rough with them they should be fine. Just applying some regular solder to try and freshen up the old stuff for de-soldering shouldn't affect them at all.

[LeonR]

Is there a term or composition for this low-temp melting wire? I'd like to check cheaper alternatives for it.

[LateLesley]

Here's a quick hack way of doing it. I've never tried it, but it might just do what you need, if you are careful.

[SuperGiachi]

Im going to get the replacement chip from another motherboard, so it should at least be able to turn on the notebook. Then i'm going to flash an updated BIOS(the manufacturer says that updating the BIOS will update the EC too, so i suppose the system is able to flash the EC firmware on its own).

[Gyro]

Here's a quick hack way of doing it. I've never tried it, but it might just do what you need, if you are careful.

Neat. An IR reflow wand! 

I just found an old bulb in the garage with the dipped filament still intact (swapped them as a pair). Time for some cautious playing.

[SuperGiachi]

After I removed the blown chip, should I solder the new one using the drag soldering tecnique and then remove the excess solder with solder wick or should I solder it pin by pin?

[LateLesley]

you will be best with drag soldering.

You will need wick to clean the pads off beforehand, and you will need flux, that is the magic ingredient to drag solder without it bridging. It would take forever to try soldering pin by pin, and you still wouldn't avoid bridges anyway. That's the job of the flux, it'll help you solder and prevent bridging between pins.

Obviously, you'll tack a couple of corners down in place before drag soldering.

[SuperGiachi]

Is there a type of flux which is best suited for this job? Will my weller liquid flux(http://uk.farnell.com/cooper-tools-weller/0051383199/flux-bottle/dp/1572843) be up to the task? If I accidentally bridge 2 or more pins, will solder wick fix that?

[wraper]

Is there a type of flux which is best suited for this job? Will my weller liquid flux(http://uk.farnell.com/cooper-tools-weller/0051383199/flux-bottle/dp/1572843) be up to the task? If I accidentally bridge 2 or more pins, will solder wick fix that?

This flux should be sufficient but not the easiest to work with. The easiest to work with are tacky fluxes. You should use solder wick only on the last pins in the row if you cannot remove a solder blob otherwise.

[SuperGiachi]

What about flux residue? The board has some brown patches which i suppose are caused by burnt flux(when I tried with regular solder i was using very high temps to try to get the chip off). Some pads got covered by that gunk too. What should I do?

[senso]

IPA/rubbing alcohol..

And you can't grab a random EC and hope that it works..

EC controls the power sequence, voltage regulators, keyboard matrix scanning, on older models it also had the PS/2 port for the touchpad,and a ton of little things in a laptop motherboard, using another one, results in either no power or burned components..

[SuperGiachi]

The fact is that i'm getting the EC from a very similar laptop, hopefully the power sequences will be the same. The CPU is almost the same. I only need it to power on and get to the bios, from which I can reflash the EC firmware that is included with the bios file(https://www.asus.com/supportonly/BU201LA/HelpDesk_BIOS/   version 204). Do you think this will work? This notebook was originaly bought for spares anyway, so if it dies i don't care.

[cheeseit]

I don't know if it'll work or not but I'm leaning towards not, though I hope it will. I'm curious to see the result, and as to how you determined that the EC was blown in the first place?

Also, how about buying a cheap hot air station instead of chip quick? It would be way more useful for other things in the future too. Then you could also practice removing another chip or two from a scrap board and afterwards try the drag soldering technique before you commit to doing it on your motherboard.

[SuperGiachi]

The EC had a hole in it so it was definitely broken. The 5V and 3,3V power supply is bad too, I'll get away with two LDOs for now.

[Bashstreet]

The EC had a hole in it so it was definitely broken. The 5V and 3,3V power supply is bad too, I'll get away with two LDOs for now.

The EC might not function if you swap it and it is not exactly same. Still as experiment why not try long as you are aware it can do more damage (maybe).

[SuperGiachi]

The EC is exactly the same and will be pulled from another motherboard based on the same platform(Haswell-U). I'll try and report the results here.

[SuperGiachi]

I finally ordered the Chip Quik alloy and desoldered the EC. I noticed that i lifted a solder pad and bent another one when trying desoldering the EC with regular solder(probably because of the high temps i used). I decided to desolder it with chip quik anyway, and unfortunately i realised that the solder pad got completely off . Both of the pads are connected to exposed pcb traces(top layer). Here are some photos
https://drive.google.com/file/d/0B_r8p2JWpx1DZFhHLUoyQ2hPVUdBbFBQNHVkX2FzR1NZVFpF/view?usp=sharing
https://drive.google.com/file/d/0B_r8p2JWpx1DN1lyTERJT0pXc1lTTXpxendkYVJYMmpYeXY4/view?usp=sharing
I also desoldered the replacement chip from it's board flawlessly(didn't ruin that board with regular solder).
What should i do now? can i solder the replacement chip directly on the trace or should i replace those pads? Is it possible to replace the pads?
Thanks in advance

[wraper]

Straighten bent pad and replace broken pad with a piece of very thin wire (take one strand from some multi-strand wire). Be sure to remove solder resist and solder the wire all along the trace till via. To ensure that when soldering IC back, solder won't completely melt and wire won't move away from the trace.