Instrumented Getter using Additive Manufacturing

Getters have been used since the invention of the vacuum tube to bind undesirable gases in vacuum systems. They are still used today in many high-reliability electronics applications. Traditional getters are open loop systems: packaged device failure may be the first sign that the getter has saturated. Some getter materials experience a change in their electrochemical properties as that bind water vapor or other gases, making their status electrically detectable. This was previously demonstrated using a polyimide PCB with an IDE sensing structure that was placed inside the sealed package with the commercially available getter attached to it. Although this design worked well, it required the addition of the sensing PCB to the sealed package. To alleviate this issue, the PCB was replaced with the sensing IDE structure AM printed onto the package lid to which the getter would be attached. The electronics inside the package would then monitor the getter status. This was successfully demonstrated using an alumina substrate for the package lid, with an AM printed silver ink IDE structure, and an adhesive backed commercially available moisture getter. A 6 day humidity chamber soak resulted in a 2.4% decrease in measurable sensor capacitance.