Method for manufacturing sensor element for use in gas sensor, inspecting electrical characteristics of sensor element, and pre-treating sensor element
To provide a method for manufacturing a sensor element, by which stabilization of an electrode, which is performed prior to inspecting element characteristics, can be performed for a shorter time period and in a more reliable manner than in the conventional. The sensor element includes: an oxygen-ion conductive solid electrolyte layer; a first electrode that is formed on a surface of the oxygen-ion conductive solid electrolyte layer; and a second electrode that is formed in a space provided inside the oxygen-ion conductive solid electrolyte layer, and that is configured to reduce said predetermined gas component. As the pre-treatment, by an external power source, a voltage is applied between the first electrode and the second electrode, to thereby decompose and remove a gas component attached to the second electrode.
1. A method for manufacturing a sensor element for use in a gas sensor that measures a concentration of a predetermined gas component in a measurement gas, said sensor element comprising an electrochemical pumping cell including:
an oxygen-ion conductive solid electrolyte layer;
a pump electrode of a pair of pump electrodes, which is formed on an outermost exterior surface of said oxygen-ion conductive solid electrolyte layer; and
a measuring electrode of a pair of measuring pump electrodes, which is formed in a space provided inside said oxygen-ion conductive solid electrolyte layer,
said method comprising the steps of:
a) forming, by printing, a wiring pattern of a conductive paste on a green sheet containing, as a main component, ceramic which is an oxygen-ion conductive solid electrolyte, said wiring pattern including portions serving as said pump electrode and said measuring electrode;
b) laminating a plurality of green sheets that have been subjected to said step a), and integrating said plurality of green sheets;
c) cutting out a plurality of element bodies from a laminated body obtained by said step b);
d) baking the element body cut out by said step c);
e) heating the element body having been subjected to said step d), in a reducing rich atmosphere so as to manufacture said sensor element;
f) performing a pre-treatment, by an external power source, applying a voltage between said pump electrode and said measuring electrode included in the element body having been subjected to said step e), to thereby decompose and remove a rich component of said step e) attached to said measuring electrode; and
g) inspecting electrical characteristics of the element body having been subjected to said step f).
2. The method for manufacturing a sensor element according to claim 1 , wherein
in said step F), a DC voltage is applied between said pump electrode and said measuring electrode under a state where said pump electrode is connected to a negative electrode of said external power source and said measuring electrode is connected to a positive electrode of said external power source.
3. A method for inspecting electrical characteristics of a sensor element for use in a gas sensor that measures a concentration of a predetermined gas component in a measurement gas, said method comprising the steps of:
providing a manufactured sensor element, said sensor element comprising an electrochemical pumping cell including
an oxygen-ion conductive solid electrolyte layer,
a pump electrode of a pair of pump electrodes, which is formed on an outermost exterior surface of said oxygen-ion conductive solid electrolyte layer, and
a measuring electrode Of a pair of measuring pump electrodes, which is formed in a space provided inside said oxygen-ion conductive solid electrolyte layer; and
applying a pre-treatment, by an external power source, a voltage between said pump electrode and said measuring electrode included in said sensor element, to thereby decompose and remove a rich component attached to said measuring electrode, and then inspecting electrical characteristics.
4. The method for inspecting electrical characteristics of a sensor element according to claim 3 , wherein
in decomposing and removing said rich component, a DC voltage is applied between said pump electrode and said measuring electrode under a state where said pump electrode is connected to a negative electrode of said external power source and said measuring electrode is connected to a positive electrode of said external power source.
5. A method for performing a pre-treatment on a sensor element for use in a gas sensor that measures a concentration of a predetermined gas component in a measurement gas, said pre-treatment being performed prior to an inspection of electrical characteristics, said method comprising the steps of:
providing a manufactured sensor element, said sensor element comprising an electrochemical pumping cell including
an oxygen-ion conductive solid electrolyte layer,
a pump electrode of a pair of pump electrodes, which is formed on an outermost exterior surface of said oxygen-ion conductive solid electrolyte layer, and
a measuring electrode of a pair of measuring pump electrodes, which is formed in a space provided inside said oxygen-ion conductive solid electrolyte layer; and
applying said pre-treatment, by an external power source, a voltage between said pump electrode and said measuring electrode included in said sensor element, to thereby decompose and remove a rich component attached to said measuring electrode.
6. The method for performing the pre-treatment on a sensor element according to claim 5 , wherein
in decomposing and removing said rich component, a DC voltage is applied between said pump electrode and said measuring electrode under a state where said pump electrode is connected to a negative electrode of said external power source and said measuring electrode is connected to a positive electrode of said external power source.