Another vote for silastic (RTV, silicone rubber, etc). I haven't used it on PCB Assy's, but I HAVE used it to hold things together that I expect to disassemble (once, or a few times - not repeatedly!) in the future. Place a bead around the perimeter and let it cure. When it's time to take things apart, slide your razor knife around the edge and the two pieces are loose in your hands. DEFINITELY use an "electronic grade" formulation - the catalysts in the other kinds are corrosive to metals over time.
Another alternative is two-sided "carpet tape". I use a lot of the stuff in the woodshop to hold two pieces together when I want them to be machined (sawed, drilled, routed, etc) EXACTLY alike. Characteristics vary quite a bit among brands. Some has adhesive that grabs and holds tenaciously; others are more easily peeled apart. Some has a very thin plastic base material that demands the two surfaces must be very flat and smooth to get adhesion; others have thicker substrates that seem to fill in minor irregularities (like wood grain) in the pieces being joined.
Dale
--- In Homebrew_PCBs@yahoogroups.com, "Richard" <richard@...> wrote:
>
>
>
> --- In Homebrew_PCBs@yahoogroups.com, "Kjell M. Myksvoll" <kmyksvo@> wrote:
> >
> > Hi,
> >
> > Probably a somewhat silly question, but...
> >
> > I need to attach a small populated circuit board on top of a
> > (much) larger, also populated, circuit board. Next it should
> > be easy to separate them, without destroying anything, later
> > on if that should be needed. That is I want to achieve the
> > same as one usually do with using spacers, but with using
> > glue.
> >
> > Is there any type of glue that can be used this? Can one use
> > "hot-gun" glue for this?
>
> Hot-glue is pretty tough stuff to remove.
>
> But I think a viable candidate is RTV rubber which comes in a tube
> like toothpaste. You can squeeze a blob on the base board and settle
> the smaller board on top of it. It will hold quite well, but you can
> remove it if you need to, and scrape it all off with a razor blade.
>
> We use it a lot for things like assembling speaker systems. You can
> use a bead of RTV around the speaker flange to mount the speaker and
> provide the seal at the same time. But it is "re-enterable" and you
> can separate it with a sharp knife and just pull the speaker off.
>