On Sat, 14 Jul 2001 at 10:20:56 +0100, Mike Harrison wrote: > >> >I would like to hear what other PIClisters use to protect their = > designs. > > > > > >One technique that appeals to me is encapsulation > >in a plastic resin or epoxy; > Waste of time - normal epoxy is easy to remove with minimal damage - > unless you find something exotic (i.e expensive) that's hard to > remove, don't think potting will give you anything else but > environmental protection! Anyone here heard of MEK? Turns epoxies into a soft glue like substance after about a half hour, an hour later and you've got an almost-clean parts set. Lame... > >* pot the whole product, good for small devices > >especially automotive ones. Only really offers environmental protection > >* pot a critical circuit or even just a PIC and > >it's crystal, etc in a tiny metal can, with just > >a pin header coming out. These tiny cans are cheap > >and can be board mounted, you see them in many > >devices now. All the user sees is the main board > >with the easy stuff, the 'smart" bit is in a little > >can with its own part number. Plastic cans are > >available too, they look like those square > >capacitors. "PIC in a can"? > Dremel..... Has no-one seen what Sega did with some of their arcade games? Run two thin, enamelled, twisted-pair wires round in a spiral, one connected between Vcc on the board and the Vcc pin, the other to Vss on the board and the Vss pin. If anyone tries to cut the epoxy with a Dremel, they end up cutting the wires (or snapping them). If they dunk it in MEK they end up stripping the varnish off the wires, too (creating a short circuit). Very nasty. > >* mount the smt chip(s) direct on the board, with a > >big blob of epoxy over it. > Easily dissolved Nitric acid works great (supposedly). -- Phil. philpem@bigfoot.com http://www.philpem.f9.co.uk/ -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body