On Thursday, July 9, 2020 at 6:42:22 PM UTC-7, rangerssuck wrote:> On Thursday, July 9, 2020 at 9:13:00 PM UTC-4, Tim Williams wrote: > > Heat it up until the package burns away. Slowly so it doesn't popcorn. > > Chip apart the ashes and find the die.> 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.
Decapping a SOT23
Started by ●July 9, 2020
Reply by ●July 9, 20202020-07-09
Reply by ●July 10, 20202020-07-10
Am 10.07.20 um 03:00 schrieb omnilobe@gmail.com:> On Thursday, July 9, 2020 at 2:41:30 PM UTC-10, John Larkin wrote: >> On Thu, 9 Jul 2020 20:06:12 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> > 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.I did read that it has to be fuming, concentrated nitric acid. Diluted acid would do more harm, against the expectations. Gerhard
Reply by ●July 10, 20202020-07-10
John Larkin wrote: ==================> > Squeeze it sideways in a vice. Sometimes the package will shear apart > and expose the chip. >** 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
Reply by ●July 10, 20202020-07-10
On 2020-07-09, klaus.kragelund@gmail.com <klaus.kragelund@gmail.com> wrote:> Hi > > For fun I need to inspect the die in a typical BC847 SOT23 plastic housing > > How do one decap that transistor?Hot fuming nitric acid: don't try this at home. -- Jasen.
Reply by ●July 10, 20202020-07-10
On Thu, 9 Jul 2020 16:14:32 -0700 (PDT), klaus.kragelund@gmail.com wrote:>For fun I need to inspect the die in a typical BC847 SOT23 plastic housing >How do one decap that transistor? >Cheers >KlausIf 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 <https://www.tedpella.com/technote_html/Reworking_Cured_Epoxy.pdf> "Chemical resistance of Polyester to common products..." <https://www.researchgate.net/profile/Jernej_Lenkic/post/Which_solvent_can_be_used_to_dissolve_the_cured_polyester_epoxy_resin/attachment/59d6353379197b8077992cbe/AS%3A383372955275264%401468414643896/download/Polyester+Chemical+Resistance+table.pdf> More epoxy dissolvers: <https://books.google.com/books?id=yC2VDwAAQBAJ&pg=PA438&lpg=PA438#v=onepage&q&f=false> -- 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
Reply by ●July 10, 20202020-07-10
On Thu, 9 Jul 2020 20:05:47 -0700 (PDT), Phil Allison <pallison49@gmail.com> wrote:>John Larkin wrote: > >================== >> >> Squeeze it sideways in a vice. Sometimes the package will shear apart >> and expose the chip. >> > >** 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. > > >.... PhilI squeezed these in a big bench vice https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1 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
Reply by ●July 10, 20202020-07-10
On Thursday, July 9, 2020 at 7:52:20 PM UTC-4, omni...@gmail.com wrote:> On Thursday, July 9, 2020 at 1:14:37 PM UTC-10, klaus.k...@gmail.com wrote: > > Hi > > > > For fun I need to inspect the die in a typical BC847 SOT23 plastic housing > > > > How do one decap that transistor? > > > > Cheers > > > > Klaus > > nitric acidWon't nitric acid also attack the metal? -- Rick C. - Get 1,000 miles of free Supercharging - Tesla referral code - https://ts.la/richard11209
Reply by ●July 10, 20202020-07-10
On Thursday, July 9, 2020 at 11:43:59 PM UTC-4, Jeff Liebermann wrote:> On Thu, 9 Jul 2020 16:14:32 -0700 (PDT), klaus.kragelund@gmail.com > wrote: > > >For fun I need to inspect the die in a typical BC847 SOT23 plastic housing > >How do one decap that transistor? > >Cheers > >Klaus > > 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 > <https://www.tedpella.com/technote_html/Reworking_Cured_Epoxy.pdf> > > "Chemical resistance of Polyester to common products..." > <https://www.researchgate.net/profile/Jernej_Lenkic/post/Which_solvent_can_be_used_to_dissolve_the_cured_polyester_epoxy_resin/attachment/59d6353379197b8077992cbe/AS%3A383372955275264%401468414643896/download/Polyester+Chemical+Resistance+table.pdf> > > More epoxy dissolvers: > <https://books.google.com/books?id=yC2VDwAAQBAJ&pg=PA438&lpg=PA438#v=onepage&q&f=false>+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 hassle to handle. It will probably need to soak overnight, don't know, I haven'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 commission. We were looking for asbestos fibers in the remains. However, there were no remains. The tiles completely dissolved. -- Rick C. + Get 1,000 miles of free Supercharging + Tesla referral code - https://ts.la/richard11209
Reply by ●July 10, 20202020-07-10
On Thursday, July 9, 2020 at 6:07:37 PM UTC-10, Ricketty C wrote:> On Thursday, July 9, 2020 at 7:52:20 PM UTC-4, omni...@gmail.com wrote: > > On Thursday, July 9, 2020 at 1:14:37 PM UTC-10, klaus.k...@gmail.com wrote: > > > Hi > > > > > > For fun I need to inspect the die in a typical BC847 SOT23 plastic housing > > > > > > How do one decap that transistor? > > > > > > Cheers > > > > > > Klaus > > > > nitric acid > > Won't nitric acid also attack the metal? > > -- > > Rick C. > > - Get 1,000 miles of free Supercharging > - Tesla referral code - https://ts.la/richard11209No, 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.
Reply by ●July 10, 20202020-07-10
On 2020-07-10 00:04, jlarkin@highlandsniptechnology.com wrote:> On Thu, 9 Jul 2020 20:05:47 -0700 (PDT), Phil Allison > <pallison49@gmail.com> wrote: > >> John Larkin wrote: >> >> ================== >>> >>> Squeeze it sideways in a vice. Sometimes the package will shear apart >>> and expose the chip. >>> >> >> ** 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 > > I squeezed these in a big bench vice > > https://www.dropbox.com/s/4nxm7m2q3j3buvc/ExFets.jpg?raw=1 > > 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.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
