The minimized structure design of alumina ceramic-titanium alloy vacuum sealed reference cavity in silicon-on sapphire（ SOS） absolute pressure sensor is introduced. The problem of ceramic fracture caused by mismatch of heterogeneous material is discussed. The stress situation of ceramic-titanium alloy packaging structure is calculated and analyzed. The residual stress of ceramic structure is reduced through the design of intermediate buffer layer

the ceramic seal failure caused by ceramic breakage is removed. Kovar material with the similar thermal expansion coefficient is selected as the middle layer. The middle layer structure is optimized by comparing the residual stress generated by the different thic

kness buffer layer. LTCC processing technology and vacuum brazing process are used to make the ceramic-kovar-titanium alloy sealing components. The component passes the high and low temperature test

and the leaking rate is less than 1 × 10

-10

Pa· m

3

/s

it is sealed and reliable

which meets the life requirement of working life of the absolute pressure sensor.