How does humidity reduce the service life of actuators (motorized valves)?

Humidity is known to cause damage to electronics. Today, we share a process by which humidity causes damage to capacitors, resistors, or PCBAs - Ion Migration Short Circuit.

Processes in which ion migration short circuits occur
Media in which ion migration short circuits occur
Main measures to prevent ion migration short circuits

I. The process by which ion migration short circuits occur.

The figure below shows how an ion migration short circuit occurs:

An electric field exists between the conductors at the ends of an insulator.
The susceptible electrolytic medium at the anode end undergoes ionization and migrates towards the cathode in response to the electric field.
When the ions migrate to the cathode, the anode and cathode are short-circuited by the conductivity of the ions.

II. Media in which ion migration short-circuiting occurs.

The main media that are prone to ionic migration short circuits on PCBAs are as follows:

PCB substrate impurities, hydrolyzable ions, etc;
Components on the PCB have electrolytes left in the plated vias that have failed to be washed away;
Solder, adhesive, and other substances susceptible to electrolysis during PCBA processing;
Dust plasma contamination, condensation, etc. accumulated on the PCBA during the use of electronic products;

III. Main measures to prevent ion migration short circuits.

The main measures to prevent the occurrence of ion migration short circuits are to keep the electronic product energization circuit (PCBA) dry and dustproof.

Therefore, the common measures are as follows:

The use of triple-proof paint is an extremely effective measure to provide good dust and moisture protection for PCBAs.
In applications where high humidity or large temperature differences cause condensation, the use of a fully encapsulated circuit board is the most prudent measure.
Finally, by equipping a dehumidifying heater, it is also a feasible measure. However, for a fully sealed chamber of IP67 or higher, the use of a dehumidifying heater does not reduce the humidity of the air inside the chamber at the initial stage of heating. Therefore, it is not possible to prevent short-circuiting by ion migration during part of the period.