PVDF made mask was taking 6 - 7 times more to reach the 4E-6 mbar than when using stainless steel substrate mask. So is it due to degassing from PVDF and so this should not be used?
It seems plausible that degassing occurs from the plastic, if that is the only thing you have recently introduced into the vacuum system. Better to use SS for a substrate mask...you will get a sharper edge and avoid shadowing effect. Is it a steel chamber? In that case you can also try baking the system to improve the vacuum level.
We tested a ~5 cm^3 3D printed PVDF part, and it took 24 hours to reach the same vacuum that we normally see in about 1-2 hours. Have you tried cycling it several times to see if the pump down time decreases?
Hi Debrati,
It is SS chamber inside glove box, we will try baking it, we don't have outer surface belt kind of heater, so we can do heating by heating boat. Also, System was started after around 10 -15 days.
Hi Charles,
As we run multiple times, now we are getting vacuum on time. But previously, we have checked 3-4 times and based on slow rate, stopped each time before reaching required vacuum. Your attempt of checking shows degassing is there in PVDF. We are thinking of using 100- 150um polyester sheet as substrate mask till we have SS made.
Was it a PVDF film with a prepared openings (drilled, cut, etched etc.), or a 3D-printed sheet?
In the former case one would not expect too much outgassing, - while 3D-parts typically provide a lot of gas loading as colleagues already mentioned.
Hi Victor,
it was a 10x10 cm2 sheet with prepared openings so the area is less than 10x10 cm2 due to openings. So as you suggested it should not increase vacuum reach time much. However, I am thinking to use thinner sheet of 100/175 um of Polyester for reduction of outgassing.
Hi all,
I again used same PVDF mask, and it is not showing any delay in reaching vacuum, so I am now using it. I checked by putting mask in room atmosphere and still no delay in reaching vacuum.
Thanks all!
Hi Saurabh,
Thanks for informing the community about solving your problem! That's really good the setup works as intended.
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