Defects for CCIT, a closer look with modern microscopy

Today we had another interesting technology in house, unluckily I had access to this technology only for a short moment. I hope there is going to be more to come.

I got an introduction by KEYENCE CORPORATION , thanks for the short demonstation. I have choosen laser drilled defects as well as capillary defects for the demo as they are what we often offer to our customer i.e. in their method development projects at be integral GmbH . Although this was only a very short demonstation that took approx. one hour including setup and shutdown, it gave a good insight what is possible with modern light microscopes in combination with scanning software. Please keep in mind that nothing here has been optimized and that all results are just coming from a demo. The laser defect used was measured to be a 5μm orifice equivalent (approx.) by helium leak testing. I wanted to know and to show to you if it is possible to see the profile of this defect. And this was quite well possible. What you can see in the profile is from the bottom of the big hole. The tiny little dark spot at the bottom is the starting point of that hole. What you can also see is that the laser beam is conical which means that the smallest orifice is at the end of the created funnel.

What is important for the gas exchange is the shape of a defect. The influence of this shape increases if only partial pressure difference are the driver for a gas exchange. That was the reason for me to take this example.

You can see that the starting point of the final laser drilling is approx. 20-25μm and the small black spot is the opening into the inside of the vial with a diameter of approx. 5μm.

Some measurements made correlate well with the helium leak rate derived diameter.

Some additional pictures show a standard capillary that we use to create very small defects below 1μm. This enables us to make measurements close to the "Kirsch limit" (Kirsch et al. 1997)

I hope you were able to enjoy the "beauty" of the pictures. I wanted to show these to you for two reasons.

1. There are not to many pictures of artificial defects for CCIT and
2. I am often asked by customers what defects should be chosen for CCIT and here are two nice examples

This little article does not claim any scientific correctness, as the pictures derived from a demonstration. It was quite impressive to me how quickly we were able to get these impression.