Decapping a SOT23

Certain MSI motherboards have that decapping-mode as a built-in feature for DPAK FETs in the CPU synchronous buck where they half-assed the high-side gate driver and just used a power FET totem pole for the high-side gate driver instead of a integrated thinger.

They under-specced it and it can get into a thermal runaway situation when e.g. the CPU fan or liquid coolant loop fails, but before the CPU thermal limiting kicks in. Pop!

Not a gentle pop. More like if the PC box is in the same floor of the house with you that'll definitely wake you up.

Klaus - I tried methylene chloride with no luck. I'm guessing that heat cured epoxyies are hardier that room temperature cured types. Next step would be a pressure capable container and a heater and a pressure relief valve.

Hul

snipped-for-privacy@gmail.com wrote:

Just curious, why do you want to see the die?

To watch them die, of course.

BC847BS (matched pair). or single:

More dead dies (including a few possible fakes):

There doesn't seem to be a search feature on the web site, but Google search works. Search for: site:zeptobars.com BC847 as in:

More:

"How to open microchip and what's inside?" Take some microchips of interest and add concentrated sulfuric acid. Container should be closed, but not airtight, so that fumes can escape (that is extremely important). Heat

bottom is baking soda - it's here to neutralize accidental spills and part of fumes.

"Part II: How to open microchip and what's inside? Z80, Multiclet, MSP430, PIC and more" Put a droplet of fuming nitric or sulfuric acid there, heat

- just concentrated (98% sulfuric or 70% nitric) won't cut it. After reaction ends - rinse with acetone, dry and put next droplet.

As a result we are getting exposed die, with all bond wires intact. The microchip still works - this might be useful if we want to probe it or modify eeprom data with UV laser.

Please remember that you have only one life to give for your profession or hobby. Otherwise, this looks like fun.

Thank you all for your answers and ideas

I am on vacation right now but will try when I get back again

The BC847 is just an example. What I am actually doing is to evaluate a competitor product of the BC847. I would like to see if the dies are really close to be the same

Regards

Klaus

For $5 per month on Patreon, you can send chips to the Zeptobars guy for decapping.

Cheers

Phil Hobbs

I would not handle nitric acid for ten thousand dollars.

Neither would I. The salary of a lab assistant should be far more than $10,000. More like around $46,000: Ask for a raise, or a hazardous materials handling bonus.

"LABORATORY SAFETY GUIDELINE, NITRIC ACID"

Or, maybe watch a few videos on how to handle nitric acid:

I had a bottle of nitric acid stored in my closet for many years. It was properly sealed in double layer polyethylene bottles and the original shipping container. Apparently, that wasn't good enough. After about two years in the closet, all the metal items also stored in the closet corroded into powder. Concentrated ( >60%) nitric acid will produce a protect oxide layer on the surface of most metals, dilute nitric acid will not, thus promoting corrosion. That was a rather expensive mistake as I eventually had to rebuild the closet down to the framing and sub-floor (because the nails rusted away). I replaced some drywall because a chemical test showed that there was some acid absorbed into the gypsum. All the metal buttons and studs from my jackets and jeans rotted away.

So, I bought a used chemical storage cabinet, installed it outside of the house, and moved my corrosives and flammables into the cabinet: Even so, I still had vapor problems in the cabinet, so I built a separate plastic box just for the nitric acid. That worked.