What's this thing on the microbolometer?

[Logan]

Hi guys.
I found a metal thing on my Scott's sensor package, it's like metal stick.
Please look at the 3 pictures, they were taken by Fraser, but we have a similar model. I marked that thing with an arrow.
That thing seems only exist on some microbolometers, not all models.
Does anyone know what's that for?
Thanks.

[Fraser]

From memory it is the getter firing pin that is used to improve the quality of the vacuum during production.

Fraser

[Fraser]

A thread you may find interesting……

https://www.eevblog.com/forum/thermal-imaging/the-ulis-02-05-01-microbolometer-an-insight-into-teh-technology-by-fraser/

Fraser

[Fraser]

The manufacturer of getters for sensitive applications such as microbolometer arrays states the use of porous getters and films that operate at room temperature. I believe these are what you find in modern microbolometers…

https://www.saesgetters.com/products-functions/applications/sensors-and-mems

I cannot see an evaporative getter being used inside a microbolometer and the exact nature of a microbolometer getter that requires an activation pin is not known to me. It is likely detailed in microbolometer research documents though.

Fraser

[Fraser]

Detail of a machine used for sensor assembly, including microbolometers. It states the getter is either heat or electrical activation.

https://bseteq.com/mems-packaging/

I assume in a microbolomter the getter material may be heated using a voltage and associated current applied to the getter pin but unlike a thermionic valve, it is a more refined process that activates the getters vacuum contaminant adsorbing properties without splattering material all over the interior of the module !

[Bill W]

Yes, it is a firing / refiring pin.  Big as it might be an amp or two going through it.

The earlier ULIS sensors also had such an arrangement although sometimes it was in the normal pinout. 

The instructions had dire warnings about overheating the whole package if you dared to try using it.  I think they recommended a copper block jig to clamp the sensor.

Never had much luck using it as a refiring repair, no doubt added in case it was useful as the whole peltier structure can outgas a fair bit.

Bill

[Logan]

Thank you guys.
I was thinking if we can repair a sensor which lost vacuum, so this is the answer

[Spirit532]

Thank you guys.
I was thinking if we can repair a sensor which lost vacuum, so this is the answer

No, if it goes up to air then the activated getter will immediately expire, and will need replacement.
It's a start-once run-many component.