Silicon Pressure Cell Fill Oil Volume Verification Methods
Confirm fill oil volume using pre- and post-injection micro-gravimetric mass checks combined with non-contact laser interferometric diaphragm dome profiling.
Surface Topography Profiling
Characterization Method
Microscopic analysis evaluates the physical texture and roughness of a substrate. In diaphragm manufacturing, surface topography profiling ensures that the metal sheets are free from scratches and micro-cracks. This characterization is performed before the deposition of thin-film strain gauges.
It helps prevent localized stress concentrations that cause premature fatigue.
Instrumentation Design
Metrological instruments used for this characterization include optical profilometers and atomic force microscopes. To perform surface topography profiling, the system scans a light source or physical probe across the diaphragm surface to record height variations. This scanning creates a three-dimensional map of the surface texture.
The resulting data enables the calculation of parameters such as arithmetic average roughness and peak-to-valley height.
Structural Integrity
Material performance is directly linked to the smoothness of the bonding surface. When surface topography profiling reveals high roughness, the adhesion of sputtered resistive films is compromised, leading to calibration drift over time. This roughness must be kept within sub-nanometre limits for high-precision sensors.
Proper preparation involves chemical-mechanical polishing to achieve the required flatness.
Measurement Condition
Environmental stability during the scan requires the exclusion of external vibrations. Mechanical isolation platforms must be used to prevent spurious readings that distort the recorded surface profile.