Repairing multi layered board of SSD after a PSU failure.

[develroo]

So the title describes what happened but the picture will show the problem




So basically a PSU failure blew out multiple drives and this SSD. The component that exploded is a TLV6208x A High-Efficiency Step-Down Converter in 2-mm × 2-mm WSON Package. Datasheet here. https://www.ti.com/lit/ds/symlink/tlv62080.pdf

So looking at the datasheet page 18 it shows how it is supposed to be laid out. Pin 2 Pin 8 (Vin) vaporized and the vias that went through the board vaporized too and burnt right through the board. The problem is the Pin 4 Pin 7 (SW)  track has melted ito the layers of the board and so is shorting to ground now and I am not sure how to deal with repairing this. My first instinct if to drill through the board and separate all the layers from that track. As all of the area around Pin 2 Pin 8 is Vin including the pad for C1 there is plenty or room to just take an enameled  copper wire and thread it through the board and manually create a via but then how do I make a pad for pin4 Pin 7  and pin 8. Pin 5

It is a good idea to drill through a multilayer board or am I going to make it worse?  Any advice will be appreciated. Thanks.


EDIT:

For reference here is the board with out the annotations and a picture of another non damaged board of the same type of SSD just with different inductors

Damaged



Undamaged




Thanks again.

[fzabkar]

It sounds to me as if the surge has punched through the DC-DC converter and damaged the load. I typically see this sort of damage when people switch modular cables (which do not have standardised pinouts) between dissimilar PSUs.

On the good PCB I would test for continuity between the inductor and the tiny bypass caps surrounding, and underneath, the major ICs. This will help you to identify the load(s).

FYI, I have compiled a datasheet database here:
http://www.users.on.net/~fzabkar/Datasheets/DATAURLS.HTM

Datasheets for SSD and Flash Drive ICs:
http://www.hddoracle.com/viewtopic.php?f=100&t=1577

These days many SSDs have electronic fuses.

PCB protection devices:
http://www.hddoracle.com/viewtopic.php?f=100&t=1615

[develroo]

Thanks for that info. Interesting stuff. The drive is from 2012 so not new by any means. There are actually 2 other Step downs of the same type  which blew as well, just with a whole lot less damage.

The Inductor is laid out exactly as the example and so it does not have via's for itself. Vout does as does PG (Power Good) as they are essentially connected together I assume does not matter if Vout is connected to PG

Regardless about what happened the question remains how to repair it. I have obtained  replacement step downs and as I said the other ones are far less damage and just blew the corner of the chip off and did not damage the traces.

Questions I need answering can I do without L1 completely in which case it makes making a pad for Vin far easier.  If not how do I isolate the trace from the middle layers of the board which is what it looks like it has melted into. Would drilling a hold to cut away any melted layer and then manually make via's with enamel wire so it does not touch any layers going through?

Thanks.

[fzabkar]

Pin 2 (Vin) vaporized and the vias that went through the board vaporized too and burnt right through the board. The problem is the Pin 4 (SW)  track has melted ito the layers of the board and so is shorting to ground now

Pin #2 is ground.

Pin #4 is FB (feedback)

Pin #7 is SW.

Pin #8 is Vin.

[develroo]

Yes I realised I mixed the pin numbers up but not their functions so pardon me for that. For references this if from the datasheet so everyone is clear



And this is how it is supposed to be connected.




Which as you can see is almost identical to how it is laid out.

However speculation about the chip, circuit and anything else is not helpful to me atm I am asking specifically how to repair a multi-layed board damaged as shown.

If it is possible to repair, how? If not then I am wasting my time speculating on it.

Thanks.

[fzabkar]

AISI, you have come to an unsubstantiated conclusion. My alternative explanation is that pin #7 is not shorted to an internal ground plane, but that one or more of the main ICs connected to the other side of L1 (ie Vout) is/are shorted to ground.

BTW, I'm guessing that your SSD is a Crucial MX100. These have sh*tty "protection" and often suffer catastrophic damage.

https://forum.hddguru.com/viewtopic.php?f=10&t=33908

[develroo]

Quite possibly. I will check tomorrow as had enough for today.

Cheers

[fzabkar]

BTW, the suggested PCB layout has a serious error. R1 should be connected between Vout and FB/R2.

[aqibi2000]

There’s a via going to VOUT.


Anyway, you don’t need to drill just need to use some jumper wire. Looks perfectly salvageable

[develroo]

There’s a via going to VOUT.

Well here are pics of the underside of the board for both the damaged on and an undamaged one.





So not sure which via you are referring to.


Anyway, you don’t need to drill just need to use some jumper wire. Looks perfectly salvageable

Could you elaborate on that? Jumper wires from where to where because so far I have established several problems not least being some pads that have evaporated.

Granted this is the worst damaged part of the board but there are 2 other identical layouts that have also blown that will need replacing but they have just blown the corner of the chip off not any structural damage that I can see.

[fzabkar]

There’s a via going to VOUT.

Yeah, I goofed.

Anyway, you don’t need to drill just need to use some jumper wire. Looks perfectly salvageable

The OP is seeing a dead short to ground at Vout. I can't see how you can fix that with a jumper.