At 01:33 PM 11/25/2008, you wrote: >John, > >If I erase IC numbers, conformal quote the board and put the board in >epoxy Can they still reverse engineer the board? > >Andre Pretty much, yes. The first thing they do is x-ray everything and then they know what the chips are. Then they remove the epoxy. The formula I have seen is Methyl Ethyl Ketone (MEK), Aceton and Toluene - most people say in equal parts. Working in a fume hood coat the epoxy and slowly work it off. Be careful or you can dissolve the resin in the PCB laminate. Hard conformal coatings are usually epoxy, so off they come too. If the x-ray technician is good then the shading in the image will show the copper areas. Once upon a time it was common to see people do all of those things to protect their design. But the reality is that if someone wants your design they will get it. One fellow I worked for many years ago used to remove the IC part numbers and then coat the boards in a rubber gunk that was truly disgusting to try and remove. Far worse than conformal coating. He went to a lot of trouble, but I told him, you aren't really protecting yourself. He didn't believe me, but I gave a board to a friend who had access to a low poewr inspection type x-ray. He set up and x-rayed very TTL and linear IC he had - so now he had a set of master patterns. The he x-rayed the board and the next day rang my boss and told him what the IC's were. He was incredulous. Then about two days later he came back with the complete schematic, and he had even hand built a prototype of the circuit just to check he had gotten things like resistor values right. The truth is there is really no easy way to protect your design. You can keep it away from the prying eyes of the curious, but are they a real threat to you? If your product is that important or profitable or desirable then whatever you do will only delay the reverse engineering experts by a few days. Here is another example. this time about chips. I had been supplied some supposedly Intel CPU chips recently. I was suspicious, because the top surface didn't look right, it had a different texture to what I would have expected. We tried two on boards - no go. So I had them x-rayed. Within hours I knew they were fakes - they would never work because the chip inside was something totally different. I could actually read the manufacturers markings on the dice. John >-----Original Message----- >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf >Of John Day >Sent: Tuesday, November 25, 2008 9:20 AM >To: Microcontroller discussion list - Public. >Subject: Re: PCB power plane question > >At 09:50 AM 11/25/2008, you wrote: > >On Mon, 24 Nov 2008 10:44:43 -0800, "Andre Abelian" wrote: > > > > > > > >Alan, > > > > > >In this case I can use 5 and 12 split mixed plane. > > > > > >One of my main reason I do signals in middle layers > > >is to protect circuit agents reverse engineering. Most engineers give >up > > >when they see no traces on top or bottom of the board. > > > > > > >I think that method would only deter the most casual of > >reverse-engineering efforts. > > > >If it's really worth it to someone for them to reverse-engineer your > >PCB, it would be very little trouble to depopulate a board, slap it on > >a bed-of-nails tester, and extract a netlist directly from the > >interconnects. In fact, for someone with sufficient time (or enough > >cheap labor available), they could probably do the same thing with an > >ohmmeter. > >Indeed, if you really want to reverse engineer something reasonably >simple, their are firms in Eastern Europe who will completely reverse >engineer a PCB for you. For about $1000 US they will do a 6 layer >100x160mm PCB back to schematics unless it has any BGA packages, then >it is between $1400 and $1600. > >For about $5000 they will completely recover the code in most micros >too. > >I have put signal layers between planes, but not for security - >mainly for noise reduction. But you still need to bear in mind the >issues of thickness balancing. > >John > > > >Another possibility would be to delaminate a board into its separate > >layers and view the tracks directly. > > > >Heck, it may even be possible to use Xray methods to recover the inner > >layer layouts. (Given the distances involved, though, doing that may > >not be feasible.) > > > > > >Regards, Bob > > > >-- > >http://www.piclist.com PIC/SX FAQ & list archive > >View/change your membership options at > >http://mailman.mit.edu/mailman/listinfo/piclist > > > > > >-- > >No virus found in this incoming message. > >Checked by AVG. > >Version: 7.5.549 / Virus Database: 270.9.10/1811 - Release Date: > >11/25/2008 8:29 AM > >-- >http://www.piclist.com PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist > >IMPORTANT NOTICE: This notice constitutes Proprietary Rights >identification of this email including all attachments, which is >property that is intended only for the use of the individual or >entity to which it is addressed. It also may contain proprietary >data or information that is privileged, confidential, or otherwise >protected from disclosure under applicable law. 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