Patent ID: 6116092
Filing Date: 2000-09-12
Classification: G01L

Abstract:
A pressure detector comprising a thin stainless steel flat plate diaphragm with a passive-state film (3b) formed on a gas-contact face (3a) thereof before welding, a diaphragm base (4) on which said diaphragm is mounted, and a separate sensor base (1) in which sensor chip (2) is housed and fixedly secured, and wherein said diaphragm base and said sensor base are combined and welded (8) to each other at side wall faces thereof, and wherein a pressure transmitting medium (5) is sealed in a gap between said sensor base (1) and said diaphragm,wherein said diaphragm (3) is formed in a shape of a dish and a passive state film (3b) selected from the group consisting of a chrome-oxide passive state film having a microcrystalline structure, a fluoride passive-state film, and a mixed-oxide passive-state film composed of aluminum oxide and chrome oxide is formed thereon wherein the diaphragm (3) with the passive-state film formed thereon and the diaphragm base (4) are secured to each other by brazing material (11), and wherein the diaphragm base (4) and the diaphragm (3) are secured to each other by welding (9).