The only caution I would give about CEM is consider your end-use environment: CEM, if memory serves, is more susceptible to wicking water over time, internally, and between layers (in multi-layer boards) in high humidity environments, with eventual (years, but still...) corrosion of traces and connections.
Also, as a side note that might be slightly relevant and perhaps of use to someone here, in tests on Peltier modules, sealing out water vapor, epoxy was the only sealant that performed well. Silicone, surprisingly, did not...I guess it's fine for bathtubs and aquariums, but where there's heat cycling water vapor can still get through the molecular matrix.
The sealants that are used on boards are acrylic based, if I remember correctly. However, potting a board usually involves epoxy. I dunno how well acrylic performs at keeping water vapor out of CEM boards, although I would think a coating of epoxy on all surfaces would work well...the key phrase there being "all surfaces"....
Best, Charlie
--- In Homebrew_PCBs@yahoogroups.com, Leon Heller <leon355@...> wrote:
>
> On 01/09/2010 00:45, acidblue wrote:
> > I found some copper clad boards on ebay that use CEM material
> > instead of the FR-4 that I'm familiar with.
> >
> > Has anyone used CEM before?
> > Is it any different from FR-4?
>
>
> I've been using CEM-1 for years. It's a fibreglass-paper composite and
> is much easier to cut and drill than FR4. I buy mine (precoated) from
> Mega Electronics.
>
> Leon
> --
> Leon Heller
> G1HSM
>