An appropriate diaphragm profile is generated into the
wafer to create the desired flexure of the diaphragm and to convey
the proper levels of strain to the silicon Wheatstone bridge. The diaphragm
may be epoxied or brazed to a sensor package. A more reliable
method of utilizing the SOS technology involves placing anSOS wafer on a machined titanium diaphragm. In this configuration
titanium becomes the primary load bearing element and a thin
(thickness under .01") SOS wafer is used as the sensing element.
The SOS wafer is bonded to titanium using a process similar to
brazing, performed under high mechanical pressure and temperature
conditions in vacuum to ensure a solid, stable bond between the
SOS wafer and the titanium diaphragm. The superb corrosion resistance
of titanium allows compatibility with a wide range of chemicals
that may attack epoxies, elastomers, and even certain stainless
steels. Since the titanium diaphragm is machined using conventional
machining techniques and the SOS wafer is produced using conventional
semiconductor processing techniques. SOS based pressure
sensors with operating pressures ranging from 104 kPa to over 414
MPa are available.