Decapping a SOT23

nitric acid

Sand it down?

They're so cheap, though...surely one has to try using a ball-peen hammer, with or without a scalpel used as a wedge? (Pro tip: wear a face shield when doing the latter!)

Klaus can try 50 of them and pick the best one in less time than it takes to assemble the opinions of SED, Youtube, etc. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com

=======================

** There is no fun in trying that idea.

** What "cap" ?

Moulded plastic encapsulation goes all over the chip.

.... Phil

--
|_|O|_| Github: https://github.com/dpurgert 
|_|_|O| PGP: DDAB 23FB 19FA 7D85 1CC1  E067 6D65 70E5 4CE7 2860 
|O|O|O| Former PGP: 05CA 9A50 3F2E 1335 4DC5  4AEE 8E11 DDF3 1279 A281

Squeeze it sideways in a vice. Sometimes the package will shear apart and expose the chip.

Use a Dremel tool to take off some of the plastic. Then add nitric acid. That does not dissolve silicon dioxide. Gold is not dissolved by nitric acid. A bare chip is revealed with no corrosion.

Heat it up until the package burns away. Slowly so it doesn't popcorn. Chip apart the ashes and find the die.

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:

That is pretty much guaranteed to make a horrible smell.

That's what fume hoods are for.

Another option, hot sulfuric acid... yeah, I'd use that one under a fume hood, too.

I did read that it has to be fuming, concentrated nitric acid. Diluted acid would do more harm, against the expectations.

Gerhard

==================

** Most likely take to top layer of the chip with it.

Happens all the time with TO220 and TO3P paks.

Only metal can paks ( TO18, TO5, TO3 etc) are amenable to chip observation.

.... Phil

Hot fuming nitric acid: don't try this at home.

--
  Jasen.

If the package is epoxy-B (one part, heat cured), then furniture stripper (methylene chloride) works fairly well. Nitric acid also works. In the distant past, I used Hysol Dissolver AC-4079 or Houghton 224, but those are no longer available. If the package is some kind of polyester resin, try isopropanol or sulfuric acid. If you don't have access to these chemicals, heated (190C) acetic acid work, but very slowly.

Reworking, Removing and Decapsulating Cured Epoxies

"Chemical resistance of Polyester to common products..."

More epoxy dissolvers:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I squeezed these in a big bench vice

just to see what they looked like, after we blew them up exploring analog safe-operating areas.

We found a couple of big switchmode fets that were good as linear amps.

--

John Larkin         Highland Technology, Inc 

Science teaches us to doubt. 

  Claude Bernard

Won't nitric acid also attack the metal?

--

  Rick C. 

  - Get 1,000 miles of free Supercharging 
  - Tesla referral code - https://ts.la/richard11209

ng

+1 on the methylene chloride. It will leave the bond wires and everything else that isn't epoxy or other organics. Very easy to get and a lot less h assle to handle. It will probably need to soak overnight, don't know, I ha ven't done this before. I do know it will dissolve vinyl floor tile (~1/16 inch thick) because I did that working for the consumer product safety com mission. We were looking for asbestos fibers in the remains. However, the re were no remains. The tiles completely dissolved.

--

  Rick C. 

  + Get 1,000 miles of free Supercharging 
  + Tesla referral code - https://ts.la/richard11209

ote:

using

No, the nitric acid does not attack aluminum or gold. Aqua regia is for gold attack. Diliute nitric acid harms aluminum.

It will depend on the concentration of the nitric acid used?.

Although aluminium reacts with dilute nitric acid to

produce aluminium nitrate and hydrogen gas, concentrated (>60%) nitric acid is such a powerful oxidising agent that it instantly causes a thin layer of aluminium oxide to coat the surface of the aluminium.

The oxide coating is resistant to nitric acid attack and therefore prevents any further reaction. This process is called passivation and also occurs with chromium, cobalt, iron and nickel.

To dissolve gold bonding wires: Aqua regia is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange (sometimes red) fuming liquid, so named by alchemists because it can dissolve the noble metals, gold and platinum, though not all metals.

You can also decap a DIP by connecting the mains across the two rows of pins. Makes a nice crater--point it away from your face when you do it.

Unfortunately it also ablates the chip. Nice bang though.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
http://hobbs-eo.com