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Method for a solid-state electrochemical oxygen pump to generate P(O2) in steady-state steady-flow gas streams in which chemical processes occur

IP.com Disclosure Number: IPCOM000010186D
Publication Date: 2002-Oct-30
Document File: 2 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a solid-state electrochemical oxygen pump to generate desired P(O2) in steady-state steady-flow (SSSF) gas streams in which chemical processes occur. Benefits include improved functionality.

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Method for a solid-state electrochemical oxygen pump to generate P(O2) in steady-state steady-flow gas streams in which chemical processes occur

Disclosed is a method for a solid-state electrochemical oxygen pump to generate desired P(O2) in steady-state steady-flow (SSSF) gas streams in which chemical processes occur. Benefits include improved functionality.

Background

        � � � � � Before the technology enabling nickel electrodes to be used in multilayer ceramic capacitors (MLCCs) was developed, expensive platinum or silver/palladium electrodes were used. The high cost of noble metal electrodes prevented the MLCCs from widespread usage. Because of the introduction of cheap nickel electrodes (MLCCs with nickel electrodes), the market has been expanding to meet the demand for decoupling capacitors. As a result, manufacturing a large volume of MLCCs with a high yield rate is becoming more important. One of the key manufacturing steps of MLCCs is the cosintering operation. Ceramic powder and nickel powder are heat-treated at temperatures in excess of 1000°C in a furnace that contains a reducing atmosphere (a mixture of CO and CO2 gases or a mixture of H2 and H2O gases). This step requires that the partial oxygen pressure be kept within a narrow range to assure that the nickel electrodes do not react to form insulating nickel oxide. The ceramic dielectric (such as doped barium titanate) must not convert to a leaky conducting state (n-type) by losing oxygen.

        � � � � � During the sintering process of thin film ceramic devices (such as ferroelectric memory, piezoelectric devices, and on-die decoupling capacitors) on any kind of electrode, a reducing atmosphere may be required for optimum defect structure and leakage properties.

        � � � � � Conventionally, a mixture of CO and CO2 gases or a mixture of H2 and H2O gases is used to control P(O2) in the MLCC manufacturing process. At low temperatures, a vast range of P(O2) values are inaccessible to the ceramic sintering processes because of the nature of the thermodynamic equilibrium that exists in CO-CO2 or...