GB/T 38518-2020Measurement of coating thickness on flexible film substrate (English PDF)

3.1 Section preparation

In view of problems like distortion or abrasive particle embedding that are caused by mechanical polishing of flexible film substrate, the use of an argon ion beam polishing machine can effectively polish the cross-section of the flexible film substrate. Under the secondary electron image or backscattered electron image of the scanning electron microscope, it can clearly distinguish between the flexible film substrate and the coating on the substrate.

The argon ion beam polishing machine is mainly composed of a sample chamber with a turbo vacuum pump and an optical microscope for sample positioning. During the polishing process, fix the sample on the sample holder; select the sample polishing area under the optical microscope; then, use a shielding plate to cover the non-target area of the sample and expose only the area that needs to be polished; after vacuuming, the argon gas passes through the ion source to generate an ion beam, which bombards the sample polishing area after accelerating and concentration clustering, and collides with the

f) If there is no standard sample of appropriate graduation value, extend the standard sample in accordance with B.2 of GB/T 20307-2006.

5.4 Installation of to-be-tested samples and standard samples

Simultaneously fix the standard sample and the to-be-tested sample on one side or both sides of the cuboid sample holder of the scanning electron microscope, so that the length direction of the standard sample is parallel to the thickness direction of the to-be-tested coating.

5.5 Obtain

the secondary electron image or backscattered electron image of the standard sample and the to-be-tested sample

5.5.1 Adjust the scanning electron microscope to the best working condition. The general requirements are.

a) Select an appropriate working distance;

b) Select an appropriate acceleration voltage;

c) Select an appropriate electron beam current;

d) Select appropriate image contrast and brightness, to make the length mark sharp;

e) Eliminate astigmatism of the electron beam as much as possible;

f) Make the image in focus.

5.5.2 Adjust the tilt angle of the sample stage of the scanning electron microscope to zero.

5.5.3 Select the appropriate magnification. in the to-be-tested magnified image on the display, the coating on the to-be-tested flexible film substrate does not exceed four-fifths of the field; the coating thickness shall be as large as possible.

5.5.4 Move the sample stage, so that the graduated image of the standard sample is in the center of the field; obtain the graduated image of the standard sample; record the actual working distance.

5.5.5 Adjust the height of the to-be-tested sample to the actual working distance of the same testing time as the standard sample. Without changing the state and other parameters of the scanning electron microscope, move the sample stage, so that the thickness direction of the to-be-tested coating in the field is consistent with the gradation direction of the standard sample, and it is in the center of the field, to obtain the image of the to-be-tested coating. […]

5.6 Measurement of enlarged image