Screwed up big. Missing Pads on 4x4mm Chip

[Pferd5]

Damn. I thought I could do it but I was wrong.
I try to repair a Board und while all the take off put on precedure some Pads got lose and came off.

Pin 2 and (18) 19,20,21,22

Pin 15 is not connected.

Can someone give me some kind of recommendations what to do / I can do?


(And why is this message und reply box so damn weird? It highlights and flickers while typing)

[MJ-meo-dmt]

Re: Screwed up big. Missing Pads on 4x4mm Chip

Patience.Patience.Patience.Patience.Patience.Patience.Patience.Patience.Patience.

Its not that bad, it could have been much worse. Anyways do you have a thin tip soldering iron if yes great. Do you have Patience? Yes?

Seat the "NEW" IC onto the pads that are still okay. Without making it worse. (Using hot air I hope) and some liquid flux. (plenty of flux)

Get some thin copper wire like the ones you get on some transformers, coat 2-4mm with solder, grab a magnifying glass and then sit and attach them. one at a time trying to not touch two pins because you will probably have trouble cleaning that.

The way I do it is to line the copper up with the pin *straight* then attach the copper to the pin first and then quickly to the trace. This way will require you to keep the copper straight and still because heating one end will heat the other end at the same time...

Another way would be todo everything with the iron. First lay down the missing traces extending them from the bits that are left(from the broken ones) and then attaching the IC back on doing pin by pin. But I found this way to only work on ICs where the pins are exposed on the side like a EC.

Either way you will have to make new "traces" how you do that is up to you really. Use thin copper wire, also keep in mind that you can't go too thin, some traces require a a certain thickness.(High current ones for example)

Good luck.

[Pferd5]

Re: Screwed up big. Missing Pads on 4x4mm Chip

there a several problems.
I have the new TS80 and only the one big tip (like 4 Pins width).
Hotair is available.
some chinese 0.1mm wire is also available. (isolated)
The Chip is a BQ25700 which has no pins coming out, they are just on the side. like this:

Thin wire stuff is not recommended I guess, as its the chargeing controller. I thought to repair it with some copper sheet, kapton tape and epoxy. - But I've never done this before, so I think it will not be an easy job or won't work at all (lack of experience).

I thought about creating new pads (attached to kapton tape, solder with lead free solder, place with epoxyand solder the chip with leaded solder.) - in think it will work in theorie but this is all so damn small. like 2pins on 1mm.

[SMDFlea]

Re: Screwed up big. Missing Pads on 4x4mm Chip

The 0.1mm wire is ok for that size qfn and pads. You can use thicker wire,as suggested already from a transformer, or a coil. You can flatten the end of thicker wire down with a vise or pliers to make a pad .Get the smallest tip you can get for that iron .

[stj]

Re: Screwed up big. Missing Pads on 4x4mm Chip

dead-bug method IMO.

[tibd]

Re: Screwed up big. Missing Pads on 4x4mm Chip

if u r ready to send it to Sweden with prepaid return postage I'd gladly fix it for you free of charge. Otherwise dead bug method as suggested above.

[ktmmotocross]

Re: Screwed up big. Missing Pads on 4x4mm Chip

not so hard.

try to wire missing paths under gpu

use that thin wire, the big pad is for cooling so with thick wire it be bad for connecting to cooling pad

[Pferd5]

Re: Screwed up big. Missing Pads on 4x4mm Chip

currently I may would go with the option to ship it to sweden.
I just don't want to make it worse and with no smaller tip I just can't do it.

Thanks for the help so far. I will reply when I finaly decide what to do.