Interestingly, though it does not answer the above question[1], there was talk about a month ago about using wood in satellite construction.
Though that doesn't solve many of the problems some people thought it might.[1] Because, really,
nothing answers the above question[2] unless you go for some sort of exotic material made of... let's say... baryonic matter tuned to near simultaneously undergo its proton-decay shortly after the extremely well-planned lifetime of the mission has completed.
[2] Nothing self-contained. I suppose theoretically you could send up a small tank of acid capable of eating away
exactly the whole of the vehicle into liquidised then gaseated molecules that quickly disperse to become nothing more than a neutralised cloud of vapour upon a command to the pump/valve... Except that the acid-tank/valve (and maybe the pipework, though that could be cleverly
just resistant enough) wouldn't dissolve/disperse (otherwise it would from the moment of filling) so you need another strategy there... maybe cryogenically stabilised low-MP/BP, but acid-proofing, wax kept in check by the fluids held to it by the acid-susceptible exterior. ...if manufactured in orbit, I suppose you could just freeze-cast your 'wax-sat', or other cryogenically-stable structure/etc, coat with foil as you fill with your supercool fluid and plug with the small 'charge' that (connected to the minimal and 'spaghetti-distributed' active components) you could later command to pop, release the coolant that remains (doubtless you'd need a boil-valve anyway) so that eventually the spaghetti is revealed and disentangles into a form that drifts free of itself... although how you'd make sure that all surviving
useful components are effectively less damaging than a paint-chip,
all across the orbital cross-section of the debris field (until retarded into the atmosphere or blown away by solar wind) I'll leave you to work out. Mercury used as the primary conductive material? How does that behave in vacuum pressures, at various degrees kelvin?