Replacing laptop EC without hot air station. - Page 1
Forum section: electronics / repair

author: SuperGiachi
author_rank: Contributor
timestamp: June 17, 2018, 02:15:21 pm
content: 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.

author: wraper
author_rank: Unknown
timestamp: June 17, 2018, 02:21:46 pm
content: 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.

author: JFJ
author_rank: Regular Contributor
timestamp: June 17, 2018, 03:33:34 pm
content: 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:

author: SuperGiachi
author_rank: Contributor
timestamp: June 17, 2018, 03:51:20 pm
content: Wound such an alloy mix with the rugualar solder and lower the overall melting point?

author: tsman
author_rank: Frequent Contributor
timestamp: June 17, 2018, 07:40:42 pm
content: Quote from: SuperGiachi on June 17, 2018, 03:51:20 pmYes. 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.

author: SuperGiachi
author_rank: Contributor
timestamp: June 17, 2018, 08:36:17 pm
content: I just watched the video and realized that he explained that in the beginning. Thanksguys for your advices, I'll try this chip quik.

author: SuperGiachi
author_rank: Contributor
timestamp: June 17, 2018, 10:36:41 pm
content: 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?

author: Terry01
author_rank: Frequent Contributor
timestamp: June 17, 2018, 11:29:16 pm
content: Quote from: SuperGiachi on June 17, 2018, 10:36:41 pmSo 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.

author: LeonR
author_rank: Regular Contributor
timestamp: June 19, 2018, 10:17:16 pm
content: Is there a term or composition for this low-temp melting wire? I'd like to check cheaper alternatives for it.

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 20, 2018, 02:39:19 am
content: 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.

author: SuperGiachi
author_rank: Contributor
timestamp: June 20, 2018, 02:08:13 pm
content: 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).

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2018, 04:01:46 pm
content: Quote from: LateLesley on June 20, 2018, 02:39:19 amNeat. 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.

author: SuperGiachi
author_rank: Contributor
timestamp: June 20, 2018, 09:41:43 pm
content: 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?

author: LateLesley
author_rank: Frequent Contributor
timestamp: June 20, 2018, 10:32:28 pm
content: 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.

author: SuperGiachi
author_rank: Contributor
timestamp: June 20, 2018, 10:51:46 pm
content: 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?

author: wraper
author_rank: Unknown
timestamp: June 20, 2018, 11:29:03 pm
content: Quote from: SuperGiachi on June 20, 2018, 10:51:46 pmThis 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.

author: SuperGiachi
author_rank: Contributor
timestamp: June 21, 2018, 09:31:17 am
content: 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?

author: senso
author_rank: Frequent Contributor
timestamp: June 21, 2018, 10:07:59 am
content: 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..

author: SuperGiachi
author_rank: Contributor
timestamp: June 21, 2018, 01:54:30 pm
content: 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.

author: cheeseit
author_rank: Regular Contributor
timestamp: June 21, 2018, 03:08:48 pm
content: 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.

author: SuperGiachi
author_rank: Contributor
timestamp: June 22, 2018, 02:15:15 pm
content: 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.

author: Bashstreet
author_rank: Frequent Contributor
timestamp: June 23, 2018, 05:46:45 pm
content: Quote from: SuperGiachi on June 22, 2018, 02:15:15 pmThe 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).

author: SuperGiachi
author_rank: Contributor
timestamp: June 28, 2018, 01:06:32 pm
content: 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.

author: SuperGiachi
author_rank: Contributor
timestamp: August 20, 2018, 11:59:16 am
content: 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 photoshttps://drive.google.com/file/d/0B_r8p2JWpx1DZFhHLUoyQ2hPVUdBbFBQNHVkX2FzR1NZVFpF/view?usp=sharinghttps://drive.google.com/file/d/0B_r8p2JWpx1DN1lyTERJT0pXc1lTTXpxendkYVJYMmpYeXY4/view?usp=sharingI 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

author: wraper
author_rank: Unknown
timestamp: August 20, 2018, 12:12:30 pm
content: 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.

author: SuperGiachi
author_rank: Contributor
timestamp: August 20, 2018, 12:20:39 pm
content: So I have to scratch the trace to reveal copper and solder a thin wire to the missing pad footprint, right?

author: wraper
author_rank: Unknown
timestamp: August 20, 2018, 12:31:39 pm
content: yep

author: SuperGiachi
author_rank: Contributor
timestamp: August 20, 2018, 01:48:08 pm
content: How can I secure the wire to the pad so that it doesn't move? Do i have to solder the wire all along the trace?

author: wraper
author_rank: Unknown
timestamp: August 20, 2018, 02:07:28 pm
content: Quote from: SuperGiachi on August 20, 2018, 01:48:08 pmIt would be preferable to solder all along the trace. But it does not really need to be secured as it will be fixed in place once you solder it to the terminal of IC.

author: SuperGiachi
author_rank: Contributor
timestamp: August 20, 2018, 03:35:24 pm
content: I scratched the trace till i saw exposed copper.https://drive.google.com/file/d/0B_r8p2JWpx1DcmRUTGtSNVA4Ynl0T1ZvcmFmeGdLcnByUDk4/view?usp=sharingIs it good enough should I scratch it more? Is the thin wire in the video(it is not solder, it is one core of a multi-core wire) thin enough?Is it possible to drag solder the chip without bridging everything?

author: wraper
author_rank: Unknown
timestamp: August 20, 2018, 03:54:52 pm
content: Exposed copper is enough. It is possible to drag solder. You may need some solder wick to remove bridges on the corner terminals. Of course you should not use drag soldering on damaged pads. Wire on the photo is way too thick. Search for some wire with thinner strands.Aso solder the wire to terminal among the first (after touching up some corner pins so chip does not move) so you can fix it without desoldering the whole chip if something goes wrong. Also do it fast to avoid wire heating up and desoldering from the trace on the other end.

author: SuperGiachi
author_rank: Contributor
timestamp: August 20, 2018, 04:39:49 pm
content: Is this still too big?https://drive.google.com/file/d/0B_r8p2JWpx1DcmRUTGtSNVA4Ynl0T1ZvcmFmeGdLcnByUDk4/view?usp=sharingShould i tape it down on one side to get it in position while soldering? Also, can i clean the solder pads using solder wick or do i risk damaging them?Will a wire from solder wick be thin enough?

author: wraper
author_rank: Unknown
timestamp: August 20, 2018, 06:05:46 pm
content: It's the same picture.

author: SuperGiachi
author_rank: Contributor
timestamp: August 20, 2018, 06:07:31 pm
content: My bad, uploaded the wrong onehttps://drive.google.com/file/d/0B_r8p2JWpx1DajFETkcyVm9WN0dCZFVKeHMzdEV2V3B1aHlR/view?usp=sharing

author: wraper
author_rank: Unknown
timestamp: August 20, 2018, 06:24:04 pm
content: Well, you could use it if you really don't have anything else. But it's thick as a pad width. You could tape it down for convenience and then cut the end of it after soldering.

author: Gyro
author_rank: Super Contributor
timestamp: August 20, 2018, 07:31:56 pm
content: Use a strand from your solder wick.

author: SuperGiachi
author_rank: Contributor
timestamp: August 21, 2018, 11:29:16 am
content: I tried soldering the solder wick wire, but solder doesn't adhere to the substrate. Can i solder a wire to the trace and run it through a corner of the chip and then solder directly to the pin by routing it on the top of the chip? I would glue the wire down to the pcb underneath the chip to avoid unwanted contacts.

author: Gyro
author_rank: Super Contributor
timestamp: August 22, 2018, 08:50:40 am
content: Yes, the solder won't adhere to the substrate once the pad has gone. Soldering it to the track and then bringing it out to the pin position should be fine. You ought to be able to just bring it out where the pad would have been and then just solder it to the underside of the pin. Just make sure it is correctly located when you place the chip.

author: SuperGiachi
author_rank: Contributor
timestamp: October 07, 2018, 07:46:16 pm
content: I'm back again with another questionI have to replace the power supply controller IC(3.3V and 5V in one chip) and this chip happens to be a 20 pin QFN with a thermal pad, so I can't solder/desolder it with a soldering iron. Since I can't afford a good hot air rework station and don't want to buy a cheap one that will need to be replaced and/or has dangerous wiring, would it be possible to get by with an heat gun(like the one you find in hardware stores)? I wouldn't use it often, just for the replacements that I can't perform with a soldering iron alone.

author: wraper
author_rank: Unknown
timestamp: October 07, 2018, 08:06:31 pm
content: Quote from: SuperGiachi on October 07, 2018, 07:46:16 pmIf your goal is instant death of motherboard, then go on. FWIW cheap 858D hot air station from aliexpress is a good choice if you don't have money for something better.

author: SuperGiachi
author_rank: Contributor
timestamp: October 07, 2018, 09:05:14 pm
content: Would it damage something even at the lowest setting(350°C)?

author: wraper
author_rank: Unknown
timestamp: October 07, 2018, 09:44:39 pm
content: Quote from: SuperGiachi on October 07, 2018, 09:05:14 pmYou will melt the solder all around and most likely blow off many components. Not that there is actual temperature regulation to begin with.