I'm making a custom PCB to plug onto the top of an Uno R3. Of course, this tends to "enclose" all the Uno components, and it's in an environment which can get warm. (Trunk of a car, during summer.) My added components on the new PCB are to the side of the Uno, which means I can add cutouts above the Uno components which tend to be vulnerable to heat -- To promote better airflow.
A previous version of the project naively assumed the Uno wouldn't be vulnerable to overheating, so it was in a nearly-sealed enclosure. Bad idea, methinks. My sketches locked up after a while. And YES, I'm pretty sure it wasn't memory. code, or power issues. (I'm aware that a car power supply needs good voltage regulation. It has that.)
Nothing was cooked, but the sketches locked up sometimes. Resetting gets the sketches running again.
I don't want "holes everywhere" because the PCB would become flimsy and it would be more vulnerable stray objects creating shorts.
So, I need to know:
Please confirm that heat can cause such issues without necessarily destroying the Uno, right? If I'm wrong, then I'll triple-check code and memory management, but those seem solid and my power regulation is good too.
What components on an Uno R3 are in greatest need of a good flow of air in a warm environment? (At this point it doesn't seem necessary to add a fan.) Is it the main chip? The caps?