Anyone know about stress tests?

Originally posted by sonhouse
The deposition is done in a vacuum chamber with argon as background gas. There is a target of the material to be deposited, and the volume between the target and the platen is charged with RF at about 500 to 1000 watts, which ionizes the argon. Now argon, at 40 AMU is a fairly heavy atom and when ionized like that it has a degree of kinetic energy that will ...[text shortened]... built up with as little stress as possible.
Don't know if I can put it much better than that.

Unfortunately, this is one of those instances where a diagram is worth a thousand words. I'm assuming the induced stress comes from inter-molecular forces, and i'm still not able to visualize how the thin metal strip interacts with the system ( this type of procedure/process is just too foreign for me). Ideally you would want to know the resultant inter-molecular force (if what I said above is true) and its mode of application to the thin metal strip. If you know how the force acts on the strip, and you have the ability to replicate the loading condition with some degree of certainty, then give it a try. Its just.... without a theory, its hard to say how much stock you should take in the results.

Originally posted by joe shmo
Unfortunately, this is one of those instances where a diagram is worth a thousand words. I'm assuming the induced stress comes from inter-molecular forces, and i'm still not able to visualize how the thin metal strip interacts with the system ( this type of procedure/process is just too foreign for me). Ideally you would want to know the resultant inter-m ...[text shortened]... y. Its just.... without a theory, its hard to say how much stock you should take in the results.

We want a means of predicting the delamination potential of the resultant coatings. The ionized argon is what knocks off molecules from the target which is the desirable coating material, could be aluminum, could be titanium, could be SiO2, SiC or other materials. The target is what supplies the material to coat the substrates, in this case our substrates are alumina with patterns on them and if we put too thick a layer there is a tendency for the coating to delaminate, bits of it breaking off. So we put the thin metal piece in with the substrates along with a thickness monitor, which is measured with a Dektak thickness measuring tool, which is accurate to less than 100 angstroms. We coat from 6000 to 8000 angstroms. The target material mixes with the argon to make a cloud of the target material which coats whatever is sitting close by. The argon does not participate in the coating process. A video wouldn't help much because the process takes place in a high vacuum system with a lot of RF energy applied inside.

There was some relatively recent research on plasma depositing techniques for high
thermal stress components where they slowly blended the different materiel layers
do that there was a gradual transition from one materiel to the other which helps prevent
de-lamination under thermal expansion..

Don't know if such a technique would help here.

Originally posted by googlefudge
There was some relatively recent research on plasma depositing techniques for high
thermal stress components where they slowly blended the different materiel layers
do that there was a gradual transition from one materiel to the other which helps prevent
de-lamination under thermal expansion..

Don't know if such a technique would help here.

The machines for doing that kind of thing are a lot more complex than our relatively simple plasma dep machine. Our machines have three targets, which can be most anything but we use aluminum, SiO2, SiC, Si-Crome, and the like. We can only blend three layers together and the only thing we use to help SiC layer is the interstitial layer of about 300-500 angstroms of SiO2. That's about the only blending we do, but that isn't really blended, just a layer of SiO2 followed by a layer of SiC, much thicker.