I'm aware that a number of mass produced electronics are embedded in a solid thermal resin of some form.
How reasonable is that for the home hacker? What materials are used? How do you do it? Are there resources and examples available on the topic? What are the pros and cons of such a project?
It is called "potting" electronics. The electronics are constructed as normal, and then potting compound is poured in. This then sets hard and leaves what you see. It's extremely feasible to do at home, all you need it some form of container to hold the resin as it sets, and this is normally the enclosure. Do make sure the enclosure can't leak through!
Potting electronics helps with a number of issues. If the electronics are going through shock or vibration it helps keeps the components on the board and functional. It will help somewhat with moisture, although if the water is in the air, it has a tendency to get between the board and the potting compound, and then get held there.
If you have high power components, potting compound will increase the temperature as it doesn't conduct heat away as well as air, as well as losing any airflow. As the compound sets, it does tend to get quite hot, so make sure your components are up to this. Most are, but I have had some sensitive components like sensors break.
There is also outgassing. As you pour the compound in, there is a tendency for bubbles to form, which will become voids in the potting. The best way to remove this is to place the enclosure being potted in a vacuum chamber which forces the bubbles out, but at home I'm sure pouring slowly would suffice.
There are plenty of places that carry potting compound, and examples from Farnell would be:
It's called potting compound and it comes in a liquid form. You usually put the assembled board into a thin walled box and then pour in the potting compound and let it set. It is a reasonable activity for the home hacker but we aware that it is messy and the potting compound leaves permanent stains in clothing. You can buy packs from electronics suppliers, they usually come in two bags which need to be mixed to activate them.
The pros are: prevents physical tampering with the product, waterproofs, reduces effects of shock and vibration, distributes heat evenly.
The cons are: impossible to service the product, need to mask off connectors, messy, can crack if one component gets too hot (professional potting includes coating some components in a rubbery compound first to allow for expansion), adds weight, makes recycling the components virtually impossible (European WEEE directive).
I've tried this using E6000 which seemed to work well for my application and was cheap and available.
