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Repair and disassembly information for the Samsung Galaxy Note20 Ultra Android smartphone. Released in August of 2020.

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Battery Power Connector Burnt Repair

Hi, I was wondering how do I go about repairing the battery connector area.

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The phone had been exposed to some seawater after the adhesives came apart, and caused a short circuit and burnt the connectors together (both board side and battery flex cable side).

I believe that the vbat(?) and temp sense pads have been lifted off together with the burnt power connector component. The other pads still have some copper on its surface for soldering.

How do I fill and restore a makeshift pad? I have tried using a hot air gun, but I believe the board is too cold for solder paste to melt together. I don't own a rework/reflow station, and hoping not need to purchase one.

I was thinking if a lower temperature solder paste would work? Or would silver conductive epoxy such as MG 8331S can be used to remake the pads (not sure if solder can join on top of the silver epoxy)?

I'm trying to resolder this SMD part (https://phoneparts.mt/product/samsung-bo...) back onto the board.

Thank you.

Edit1: Picture of the area around. (It's still a stacked motherboard.)

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Edit2: Schematics of the logic board.

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Post a picture showing more area. There may be nothing left to build a pad so you may consider running jumpers instead.

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Hi @oldturkey03, what kind of picture would be good? I'm using a handheld microscope so the area shown may be limited.

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@zacksg maybe with a mobile camera showing the board?

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@zacksg I don't think that any epoxy will work here. The old solder pads are pretty much non-existing and there is an awful lot of copper exposed which may just lead to further short-circuits. See if you can get a boardview on this and where those pins are connecting to next. Then run jumpers from the new connector to the first component of that circuit instead of trying to rebuild something that really isn't there anymore

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@oldturkey03 I've previously coated the exposed copper with epoxy and could do it again to prevent possible short circuit.

Do you know any resources to get boardview? I was considering whether to solder wires on the PCB to connect the battery connector component somewhere off the board e.g. on a cardboard 'as an external circuit'.

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@zacksg sorry I do not have anything higher than N976. You may have to check around the different forums etc. and see if anyone has a ZXW etc file for this.

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@oldturkey03 what wire size/gauge would you recommend? The issue I have now is the soldering onto the exposed copper of the motherboard.

Alternatively, do you think i can use normal epoxy to coat the exposed copper, then use silver epoxy to join wires to a new makeshift circuit (since my challenge is soldering things on with non-existent pads)?

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@zacksg I have used fingernail polish in the past to cover the copper. So that is not the issue since it's relatively easy, as long as you do not go overboard. At this point you really have nothing to lose so you can always try your silver epoxy and see if it works enough to get this reconnected. Just make sure that any further repair etc. considers this a pretty weak spot and a definite point of future failure. Go for it!

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@oldturkey03 I have added a photo of the schematics of Note20 Ultra for the battery connector. Not sure if it would help in understanding more.

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