Epoxying over chip numbers?

Acetone has about the same effect as water; the dremel tool can do a lot of damage if one wants...

Epoxy will be of no use. Sanding, grinding or laser abrasion are the only effective ways of "hiding" (removing) part numbers. Use of FPGAs, PALs or micros is standard industry practice, and coding is usually kept in house (also standard industry practice. If you want to confuse the troops, add logic and linear that does no useful purpose, but looks like that it is being used. Also, put some critical traces under ICs with other traces that look like they are needed both under ICs and visible, that do no useful function. Try added layers with used and extra traces; blind vias, etc.

Housesomeever, it all can be eventually decoded by someone with the right tools and time...

I think that removing the legends off ICs will only pique someone's interest, and therby hasten the eventual "decoding".

FPGAs, PALs and micros all have been used in prototypes...

With this long discussion, we still don't know what it is...its like a soap opera, Who killed JR?

Regards, Sal Bris> OK, we've determined that anyone who covers chip numbers will burn in

Ha!

It's more like - what the hell WAS in the case in Ronin :-)

Yours, Mark.

Sal Bris> With this long discussion, we still don't know what it is...its like a

In message , John Muchow writes

If they're though-hole chips, fold the legs over and mount the chip on the reverse side of the board (or re-lay the PCB). Or, instead of a Dremel, use a sheet of emery paper flat on the desk and erase the markings before soldering.

Cheers

How many protos are you talking about? 10s, 100s, more?

Can you just pot the entire board? Or do you need to have subsequent access to it?

Several have mentioned laser etching -- I'm presuming that you don't have immediate access to one of those, nor want to spend $25k for one at the moment... You may be able to achieve this in a cost-effective way by visiting your local sign/engraving shop. Most have (on-site) access to a laser engraver which should perform adequately well in a situation as this. You could probably get the cost down pretty low per piece as well.

To use epoxy and make it stick, you'd have to sand the chips anyway. But you can get a more aggressive wheel than an eraser! I work in a weld shop, and they have little (air-operated) angle grinders, just like a Dremel, but with a right angle at the business end, so you can use a sanding disk, or whatever it's called. :-)

Was it really the girl's head in the box?

How many prototypes are we talking about here anyway?

Good tips, thanks. And you bring up a very good point about piquing someone's interest!

But, for the prototypes we're hoping that the short time each user has them makes it improbable (famous last words) that they'll reverse engineer everything.

John Muchow

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Two great ideas I would have never thought of. We tried manual sanding with the paper wrapped around various objects and the chips in conductive foam...but it didn't work well at all.

Thanks! John Muchow

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Several lots of 5-10pcs. This will be a regular thing as new products are developed so we're looking for good ideas for use now and in the future.

Good idea but we need access to right-angle DIP switches from the sides of the boards.

Ummm....not just yet. :-)

Interesting idea and definitely worth considering if we were going to remove numbers from the chips in the production runs.

Hmm, wait a sec.....we do have a couple of chips that are used in every product. Might be worth lasering a couple hundred of each for future prototypes.

Good idea, thanks!

John Muchow

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Don't exactly pot the board, but conformal coat it really thick with something tough and opaque. In either case, just mask off the switch.

I was gonna respond to another comment, about a safer method, by saying "operator training." ;-)

Find out from your chip vendor what it costs to get house numbers on, say, 1000 parts. You might save money, not to have to pay somebody to sand chips. Just make up some random part numbering system, and keep it a secret. BZQX == 7400 #q87S == CD4060

etc. (of scourse, you could make up house numbers that sound like actual house numbers, like 04-101, 03-227, and so on. be careful not to lose the cross-reference!)

Like when Peggy Hill said to the shoe guy, I'd like a pair of women's size 16 bowling shoes, marked 8 1/2. He measures her foot, and says, "No, you want a pair of women't size 16 _and a half_ bowling shoes, marked 8 1/2." I think she cried. ;-)