C-cages with silicon wafers attached to each of the six faces were tested with and without the Parylene coating. The objective was to observe how much the silicon constrained the expansion and contraction of the Rohacell as it was exposed from low to high humidity.
Comparing figures 6a and 7a, it can be seen that the
silicon does influence the expansion of the widths. While the total
change in width for the parylene cage with no silicon was approximately
=0.65%, the total change in width for the parylene six-silicon
cage was =0.3%. This indicates that the silicon decreased the
expansion of the width by an approximate factor of two. Therefore, doing
the same extrapolation as done for the widths in section 4.1, the silicon
keeps the width from exceeding the -0.4% mechanical tolerance.
A comparison between a parylened six-silicon cage and a non-parylened six- silicon cage shows the same results as the bare cages, with and without parylene coatings. During the transition from low to high humidity, the parylene perturbed the changes during the 40 hour time period (from 260 to 300 hours) again by a factor of two. The radial distances never exceeded the +/-1.7% physics constraint. The addition of silicon did not constrain the changes in the radial dimension because the wafers do not restrain this dimension.
The change in length for the six-silicon coated and uncoated cages (See figure 7b) show similar results as the bare coated and uncoated cages. When the environment was changed, there was a factor of two difference in the amount of change in length between the coated and uncoated cages during the 40 hour time span between 260 and 300 hours.