Gas sensor

• US 5,837,886 A
• Filed: 06/27/1997
• Issued: 11/17/1998
• Est. Priority Date: 06/19/1995
• Status: Expired due to Term

• Current Assignee: FIGARO Engineering, Inc. (New Cosmos Electric (Shanghai) Co. Ltd.)
• Original Assignee: FIGARO Engineering, Inc. (New Cosmos Electric (Shanghai) Co. Ltd.)
• Inventors: Inoue, Tomohiro, Nakahara, Takeshi, Machida, Hironobu
• Primary Examiner(s): Williams, Herzon E.
• Assistant Examiner(s): Politzer, Jay L.
• Application Number:
  US08/884,507
• Time in Patent Office: 508 Days
• Field of Search: 73/31.06, 174/262, 338/34
• US Class Current: 73/31.06
• CPC Class Codes: G01N 27/12 of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid , for detecting components in the fluid

Abstract

A film heater and thick-film electrode pads are provided on one main surface of a heat-resistant insulating substrate and are connected by through holes to a metal oxide semiconductor film on the tail surface. Pads are made of a gold alloy such as Au--Pt and connected to leads of Pt--W, etc.

Claims

1. A gas sensor comprising

a heat-resistant insulating substrate:

a metal oxide semiconductor film that changes its electrical resistance according to the presence of gas,

a film heater.

a plurality of thick-film electrode pads, each provided on the heat-resistant insulating substrate; and

precious metal alloy leads

wherein said metal oxide semiconductor film, said film heater and leads are connected to said plurality of thick-film electrode pads,

wherein said plurality of thick-film electrode pads are made of a precious metal alloy containing gold, and wherein the connections between said leads and said thick-film electrode pads are covered by thick films of precious metal.

2. A gas sensor as recited in claim 1, wherein the thickness of the electrode pads is in a range of 5-20 μ

m.

3. A gas sensor as recited in claim 1, wherein said thick-films of precious metal comprise at least one of Au, Au--Pt, Au--Rh.

4. A gas sensor as recited in claim 1 wherein the ends of said leads are fused to said thick-film electrode pads.

5. A gas sensor of claim 4 characterized in that four said thick-film electrode pads are provided and arranged at four vertexes of a quadrangle, one said lead is connected to each of said thick-film electrode pads, and each lead is virtually parallel to a diagonal of said quadrangle that passes the thick-film electrode pad to which said lead is connected.

6. A gas sensor as recited in claim 4, wherein the thickness of the electrode pads is in a range of 5-20 μ

m.