In a cleanroom—especially those used for semiconductors, optics, or aerospace—the presence of silicone is a not allowed. While silicone is a fantastic insulator and thermal conductor for standard power supplies, it is a "mobile contaminant" that can cause catastrophic failures in high-precision environments.
Even at room temperature, but especially when a power supply gets hot, silicone molecules can evaporate from internal components (like potting compounds, thermal pads, or gaskets). This is called outgassing.
Silicone has extremely low surface energy, which makes it a very effective "non-stick" agent.
The Problem: If trace amounts of silicone settle on a wafer or a PCB, it acts like a microscopic layer of oil.
Failure: Subsequent layers of photoresist, metal, or adhesives will not "wet" or stick to the surface. This leads to delamination, where the different layers of a microchip literally peel apart.
In industries like automotive painting or thin-film coating (common in cleanrooms):
If silicone outgasses near electrical contacts (like relays or connectors inside the cleanroom tool):
The silicone can degrade into silicon dioxide (SiO2), which is a high-quality insulator (glass).
This creates a non-conductive film on the contacts, leading to intermittent signal failures or complete electrical "opens" in the system.