Burst Pressure III
This is a follow up to my previous post, “Burst Pressure Probability II”. I burst 111, 30nm thick single window pnc-SI TEM chips of ten different window sizes, to measure the burst pressure of chips with varying dimensions. Although area is a major determining factor in the pressure at which the windows break, two different windows of the same area, but of different dimensions, did not have the same burst pressure. This is shown below:
Deflection of the membrane seems to be strongly correlated with burst pressure. The experimentally measured burst pressure, versus the theoretical deflection for a given applied pressure for each window is shown below. The error bars are shown as the population standard deviation.
Below, the error bars are shown as the standard deviation of the mean:
The equations used to calculate the deflection for each window size were equations 4,5, and 6 from the Vlassak paper. The aspect ratio, or the ratio of side lengths, was the determining factor in which deflection equations to use for each window.
The following shows the ten different TEM window sizes, organized according to their theoretical deflection.
The deflection for these membranes can be modeled using beam theory. Our scenario is a combination of a simply supported and fixed beam. More on this model will be included in a later post.