Patent ID: 6267009
Filing Date: 2001-07-31
Classification: G01L

Abstract:
A capacitive pressure sensor cell comprising:a ceramic substrate havinga cylindrical surface,a first major surface anda second major surface,said second major surface being opposite said first major surface,said first major surface including a concave central area which, as the concave central area extends toward said cylindrical surface, merges into a convex surface having a vertex line,said convex surface forming a planar ring surface proximate to said vertex line,a first electrode located in said concave central area of said first major surface, andan electrical connection extending from said first electrode through said substrate to said second major surface; anda ceramic diaphragm having a planar inner surface,a second electrode located on said planar inner surface of said diaphragm,said planar inner surface of said diaphragm resting on said planar ring surface of said first major surface of said substrate,said diaphragm being joined to said substrate by an active brazing solderwhich is located in a circumferential wedge zone formed between said diaphragm and said substrate and between said planar ring surface and said cylindrical surface, the circumferential wedge zone being configured to inhibit the active brazing solder from entering the concave central area,a high-vacuum-tight sensing chamber being formed between said planar inner surface of said diaphragm and said first major surface of said substrate, andelectrical connection to said second electrode being made through said circumferential wedge zone.