Post by thread:[EE]: that black substance..?

Hello, I saw some hybrid circuits drowned into a black, very hard substance, I guess to hide their "secrets". Now I need to do something similar.. I have to borrow some circuits to a customer, but I don't want him to reverse engineer them. Not only I'm gonna cancel signs/labels from the ICs, but I also (for some added security) I would like to drown most of it into this black, very hard, substance. I guess that if he tries to remove it, the circuit board will be damaged. The circuits will return to me, so I'll know if he tried to be too smart. Could anybody give me some pointers / directions, please? For a good start, I would need to know the name of this substance (to then try to translate it into my own country language). Thanks! Andrea -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

At 22.34 27/02/2004 +0100, you wrote: >Hello, >I saw some hybrid circuits drowned into a black, very hard substance, >I guess to hide their "secrets". > >Now I need to do something similar.. I have to borrow some circuits to Correction: I meant "lend", not "borrow".. of course. {Quote hidden}>a customer, but I don't want him to reverse engineer them. Not only I'm >gonna cancel signs/labels from the ICs, but I also (for some added >security) I would like to drown most of it into this black, very hard, >substance. I guess that if he tries to remove it, the circuit board will >be damaged. The circuits will return to me, so I'll know if he tried to >be too smart. > >Could anybody give me some pointers / directions, please? For a good >start, I would need to know the name of this substance (to then try to >translate it into my own country language). > >Thanks! >Andrea -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

part 1 1256 bytes content-type:text/plain; charset="us-ascii"read this... Regards Roland PS: (and it's 'lend to' and 'borrow from') At 10:34 PM 27/02/04 +0100, you wrote: {Quote hidden}>Hello, >I saw some hybrid circuits drowned into a black, very hard substance, >I guess to hide their "secrets". > >Now I need to do something similar.. I have to borrow some circuits to >a customer, but I don't want him to reverse engineer them. Not only I'm >gonna cancel signs/labels from the ICs, but I also (for some added >security) I would like to drown most of it into this black, very hard, >substance. I guess that if he tries to remove it, the circuit board will >be damaged. The circuits will return to me, so I'll know if he tried to >be too smart. > >Could anybody give me some pointers / directions, please? For a good >start, I would need to know the name of this substance (to then try to >translate it into my own country language). > >Thanks! >Andrea > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics part 2 48113 bytes content-type:application/zip; name="hack.ZIP"; (decode) part 3 328 bytes content-type:text/plain; charset="us-ascii" Regards Roland Jollivet JeM Electric cc PO Box 1460 Kloof 3640 Kwazulu Natal South Africa Tel: +27 31 7024412 Fax: +27 31 7011674 Cell: +27 83 255 6017 Email: spam_OUTenquiriesTakeThisOuTcaon.co.za -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Could anybody give me some pointers / directions, please? Epoxy resin. You can buy small quantities off the shelf in hardware stores in 5 minute or 24 hour versions for D-I-Y. Avaliable as clear or cloudy. Or as a potting or encapsulation compound from electrical/ electronic suppliers in black form. It will take some serious efforts to find out what's been encapsulated -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Or a cheap solvent. :-) -Adam Jinx wrote: {Quote hidden}>>Could anybody give me some pointers / directions, please? >> >> > >Epoxy resin. You can buy small quantities off the shelf in hardware >stores in 5 minute or 24 hour versions for D-I-Y. Avaliable as clear >or cloudy. Or as a potting or encapsulation compound from electrical/ >electronic suppliers in black form. It will take some serious efforts to >find out what's been encapsulated > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Or a cheap solvent. > > :-) Ok, I'll weasel out of that by reminding you the OP was just lending the circuits and that he'd spot any tampering Having seen the "tamper-proofing" topic debated several times I shouldn't have left "efforts as an unqualified "serious". Hackers are always a step ahead and will go to any lengths, even as an academic exercise. It's a matter of degree of course. As is often the case, reasonable steps will deter most people You could shield out X-rays with metal You could put extra dummy components inside to mislead You could put a vial of circuit-destroying acid inside You could make connections from perishable materials (eg conductive epoxy) You could use code dependent on external conditions You could add to this list For a circuit that blinks an LED, not worth it For a circuit that allows untraceable and easy access to money or services or information, worth it. Somebody somewhere will crack it eventually, but if you're smart what they've just cracked is obsolete -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

"M. Adam Davis" wrote: > > Or a cheap solvent. CHEAP? OK what cheap solvent dissolves potting epoxy? I'd love to know. Even the vicious stuff I've tried goes nowhere (fuming nitric acid for instance). R {Quote hidden}> > :-) > > -Adam > > Jinx wrote: > > >>Could anybody give me some pointers / directions, please? > >> > >> > > > >Epoxy resin. You can buy small quantities off the shelf in hardware > >stores in 5 minute or 24 hour versions for D-I-Y. Avaliable as clear > >or cloudy. Or as a potting or encapsulation compound from electrical/ > >electronic suppliers in black form. It will take some serious efforts to > >find out what's been encapsulated -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Here in India, automotive painting workshops use what they call a car-patch to fill up minor dents before painting. The main component is green, and the hardener is white (to be used in a mix of about 10:1). This stuff is extremely cheap, gets rock solid in about 15 minutes on mixing, and shows excellent electrical characteristics for this application. I have used this for potting even 240 volt operated boards. Regards, Anand {Original Message removed}

With the application of the right amount of heat, (below the damaging temp of electronics) that "car-patch" stuff will come right off. Do that all the time for other's body "repairs" gone wrong. Scott At 08:20 PM 2/27/04, you wrote: {Quote hidden}>Here in India, automotive painting workshops use what they call a car-patch >to fill up minor dents before painting. The main component is green, and the >hardener is white (to be used in a mix of about 10:1). This stuff is >extremely cheap, gets rock solid in about 15 minutes on mixing, and shows >excellent electrical characteristics for this application. I have used this >for potting even 240 volt operated boards. > >Regards, > >Anand > >{Original Message removed}

> OK what cheap solvent dissolves potting epoxy? I'd love to > know. Even the vicious stuff I've tried goes nowhere (fuming > nitric acid for instance). Methylene chloride can attack epoxy. It breaks down most alkyd and emulsion paints and resins. Often sold in a spreadable form (like wallpaper paste) as general paint stripper. I think the filler is cellulose or aerogel, something like that. It goes after paint films pretty quickly and vigourously, not sure about the time needed to eat through a block of epoxy. ISTR some organic sulphides can damage epoxy too. That's starting to get into haz-mat territory, although getting a good whiff of methylene chloride is no picnic -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Tends to craze and crack epoxy violently - delicate components > embedded in it can be mechanically damaged A moderator like toluene or xylene may curb it's aggresiveness, and they're solvents in their own right. Like methylene chloride and many polar (or fat soluble) organic liquids they'll also be absorbed through the skin and lungs, generally detrimentally to the absorbee -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

CS2 perhaps. veeery unhealty. However, any solvent that attacks epoxy will will also destroy the pcb board (epoxy) and most likely most of the electronic components as there are hardly any components that do not use some sort of resin. Anyhow, wouldn't it be easier to go the legal way. Have the borrower sign a clause that states that the design is yours and that they agree to pay a substantial fee if they turn out to be selling something that is very similar to your design. michiel On Feb 28, 2004, at 3:59 AM, M. Adam Davis wrote: > Or a cheap solvent. > > :-) > > -Adam > > Jinx wrote: > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 10:06 PM 2/27/2004 -0700, you wrote: >"M. Adam Davis" wrote: > > > > Or a cheap solvent. > >CHEAP? >OK what cheap solvent dissolves potting epoxy? I'd love to know. >Even the vicious stuff I've tried goes nowhere (fuming nitric acid >for instance). I've heard claims that paint stripper (n-methyl-2-pyrrolidone type) works. I think they use a cocktail of fuming nitric and another acid commercially (hot and sprayed under pressure). None of this is stuff I'd want around. The lab supply houses charge a lot of money, the storage and disposal costs are high. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam@spam@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Sat, 28 Feb 2004 07:58:36 -0500, you wrote: >At 10:06 PM 2/27/2004 -0700, you wrote: >>"M. Adam Davis" wrote: >> > >> > Or a cheap solvent. >> >>CHEAP? >>OK what cheap solvent dissolves potting epoxy? I'd love to know. >>Even the vicious stuff I've tried goes nowhere (fuming nitric acid >>for instance). > >I've heard claims that paint stripper (n-methyl-2-pyrrolidone type) >works. I think they use a cocktail of fuming nitric and another acid >commercially (hot and sprayed under pressure). None of this is stuff >I'd want around. The lab supply houses charge a lot of money, the >storage and disposal costs are high. Nitro-Mors paintstripper (dichloromethane and methanol) will soften and swell epoxy - can take a day or two but will do the job. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On 27 Feb 2004 at 22:06, Robert Rolf wrote: > OK what cheap solvent dissolves potting epoxy? I'd love to know. > Even the vicious stuff I've tried goes nowhere (fuming nitric acid > for instance). I've used industrial acetone. It takes some time to soft the epoxi. Just put your board in a closed recipient and fill it with acetone. After a couple of hours the epoxi becomes soft and is easily removed. Mark Jordan, PY3SS -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 12.19 28/02/2004 +0100, you wrote: >CS2 perhaps. veeery unhealty. However, any solvent that attacks epoxy >will will also destroy the pcb board (epoxy) and most likely most of >the electronic components as there are hardly any components that do >not use some sort of resin. > >Anyhow, wouldn't it be easier to go the legal way. Have the borrower >sign a clause that states that the design is yours and that they agree >to pay a substantial fee if they turn out to be selling something that >is very similar to your design. You said it. It takes very little effort to gain a lot of knowledge, make your own product, but make it differ enough not to be "very similar" than the original. I prefer to make them sign it and add the epoxy anyway.. every added security is a bonus. {Quote hidden}>michiel > > > >On Feb 28, 2004, at 3:59 AM, M. Adam Davis wrote: > >>Or a cheap solvent. >> >>:-) >> >>-Adam >> >>Jinx wrote: > >-- >http://www.piclist.com hint: The PICList is archived three different >ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body