Desoldering tuya chip?

Hi, any advise how i could safely desolder this wb3s chip?

I usually use hot air gun for desoldering, but I’m worried it might melt the touchpad that’s just right next it.

I’m aware there’s esphome port and openbk for beken chips. Which i already did flash on to this, but i might’ve screwed up when i tried restoring the stock tuya firmware and now i just can’t get it to flashing mode no matter what i did.

Any ideas are welcome. Thank you in advance

Chop the sub-board up with side cutters, and desolder the edge castellations as normal.

Getting the whole assembly off in one would require something like metal foil tape to protect the main board, and if the sub-board is dead, it’s not worth it.

Chopping it up seems a bit extreme since i intend to swap it with esp

Edsyn RB641 & Edsyn ST706 are useful for this. You need to be careful with the ST706 tool as it can be easily blocked when it’s closed too hard (I had one delivered like that).

RB641 can slide under the component, you neat one or more pads and then slide the metal blade from under the component so that it separates the component from the pad. Then you continue with the next pad. The metal blade does not adhere to the solder.

Desoldering using hot air is quite difficult and you’ll likely harm the PCB.

The more difficult part is the pad in the middle of the radio module (if there is one).

I only know of this german video #59: Die Entlötklinge - YouTube - my german is not very good, but the video is not to bad and now you can translate the substitles…

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Thanks, this is quite an interesting method using the thin blade
You’re right about the touchpad since it’s right next to the wb3s chip making it difficult to apply the solder near that area.
Unless i could remove the touchpad but i could accidentally tear it off and damaging it. There’s also another matter of soldering it back to the pcb but I have no idea how it’s done.

You need to be careful with the ST706 tool as it can be easily blocked when it’s closed too hard (I had one delivered like that).

Sorry, i don’t quite understand this part when it’s closed too hard?

the touchpad

I did not refer to a touch pad.

Often In the middle of the bottom of such modules there is a “big” pad, generally soldered to ground.

But on closer look, that is not the case here as the radio is upside down. You can notice the circle though that might have been soldered to ground in other situations.

i could remove the touchpad

Now the touchpad is indeed close to the pads - I do not know how it is mounted/attached. It might be with just some adhesive.
You do have access to the top of the pad so if you heat the pad using some solder to improve heat transmission you’ll probably be able to desolder pad by pad using that tool.

closed too hard

At this position in the video you can see the blade being positioned in the tool and then by turning the handle it is “fastened” (not so obvious from the video, but you’ll understand if you have the tool).

Of course it is best to exercise the tool on something that you intend to throw away.

This may be a dumb idea…

If the current chip is dead, just stick the replacement directly on top of the dead chip and hope it passes the pins through.

I think you’re onto something there

i did an ESP chip swap before this for a 3 gang touch switch and while I was desoldering with hot air.
One of the touch pad just fell off but I could still stick t back on since it still has some adhesive, and it worked fine.
So I guess I could try that

I see, similar to hand drill

I’m unsure if it’s actually dead though, there’s some logs when I connect the tx2 pin but it just refuses to go to flashing mode.
I also just learned there’s an additional step to restore the stock tuya firmware that involves cutting some of firmware bin file.

Remove the touchpad first.

Especially because you confirm that its just attached using adhesive.