ESD dissipative ceramics
AssigneeSaint-Gobain Ceramics & Plastics, Inc.
InventorsOh-Hun Kwon, Matthew A. Simpson, Roger J. Lin
Life of this patent
Estimating the term…
Abstract
This invention relates to a dense ceramics having ESD dissipative characteristics, tunable volume and surface resistivities in semi-insulative range (103-1011 Ohm-cm), substantially pore free, high flexural strength, light colors, for desired ESD dissipation characteristics, structural reliability, high vision recognition, low wear and particulate contamination to be used as ESD dissipating tools, fixtures, load bearing elements, work surfaces, containers in manufacturing and assembling electrostatically sensitive microelectronic, electromagnetic, electro-optic components, devices and systems.
Claims77
An ESD dissipative ceramic composition formed by sintering a mixture comprising a base material and one or more resistivity modifiers for a sufficient time and at a sufficient temperature to achieve at least 99 percent of the theoretical density,
- wherein the base material comprises a tetragonal zirconia polycrystal (TZP);
- wherein the resistivity modifier comprises from about 5 vol. % to 60 vol. % of the base material and is selected from the group consisting of conductive and semiconductive materials or mixtures thereof;
- and wherein the ESD dissipative ceramic composition has the following physical properties:
- (a) volume resistivity ranging from 103-1011 Ohm-cm;
- (b) flexural strength of at least 500 MPa;
- and
- (c) voltage decay time of less than 500 ms.
An ESD dissipative ceramic composition formed by sintering a mixture comprising a base material and one or more resistivity modifiers for a sufficient time and at a sufficient temperature to achieve at least 99.5 percent of the theoretical density;
- wherein the base material comprises a tetragonal zirconia polycrystal (TZP);
- wherein the resistivity modifier comprises from about 5 vol. % to 60 vol. % of the base material and is selected from the group consisting of conductive and semiconductive materials or mixtures thereof;
- and wherein the ESD dissipative ceramic composition has the following physical properties:
- (a) volume resistivity ranging from 105-109 Ohm-cm;
- (b) flexural strength of at least 500 MPa;
- and
- (c) voltage decay time of less than 500 ms.
An ESD dissipative ceramic composition comprising from about 85 to 60 vol. % Y-TZP and from about 15 to 40 vol. % ZnO densified to at least 95% of the theoretical density by sintering as the primary heat treatment.
An ESD dissipative ceramic composition comprising from about 90 to 50 vol. % Y-TZP and from about 10 to 50 vol. % semi-conductive SnO2 densified to at least 95% of the theoretical density by sintering as the primary heat treatment.
An ESD dissipative ceramic composition comprising from about 80 to 70 vol. % Y-TZP and from about 20 to 30 vol. % LaMnO3 densified to at least 95% of the theoretical density by sintering as the primary heat treatment.
An ESD dissipative ceramic composition comprising from about 90 to 60 vol. % Y-TZP and from about 10 to 40 vol. % LaCrO3 densified to at least 99% of the theoretical density by sintering as the primary heat treatment, followed by hot isostatic pressing as the secondary heat tretment.
An ESD dissipative ceramic composition comprising from about 90 to 75 vol. % Y-TZP and from about 10 to 25 vol. % ZrC densified to at least 95% of the theoretical density by sintering as the primary heat treatment, followed by hot isostatic pressing as the secondary heat treatment.
An ESD dissipative ceramic composition comprising about 75 vol. % Y-TZP and about 25 vol. % BaO 6Fe2O3 densified to at least 95% of the theoretical density by sintering as the primary heat treatment, followed by hot isostatic pressing as the secondary heat treatment.
An ESD dissipative ceramic composition comprising AlN heat treated in argon at 1900° C. followed by rapid cooling to room temperature at a rate greater than 10° C./minute.
An ESD dissipative ceramic comprising ZrO2 and semi-conductive SnO2, said ceramic having the following physical characteristics:
- (a) predetermined decay time;
- (b) hardness greater than 10 GPa Vickers;
- and
- (c) a density of at least 99% of theoretical.
An ESD dissipative ceramic composition formed by sintering a mixture comprising a base material and one or more resistivity modifiers;
- wherein the base material comprises a tetragonal zirconia polycrystal (TZP);
- wherein the resistivity modifier comprises from about 5 vol. % to 60 vol. % of the base material and is selected from the group consisting of conductive and semiconductive materials or mixtures thereof;
- and wherein the ESD dissipative ceramic composition has the following physical properties:
- (a) volume resistivity ranging from 106-109 Ohm-cm;
- (b) flexural strength of at least 400 MPa;
- and
- (c) voltage decay time of less than 500 ms.
An ESD dissipative ceramic comprising ZrO2 and semi-conductive SnO2, said ceramic having the following physical characteristics:
- (a) predetermined decay time;
- (b) hardness greater than 10 GPa Vickers;
- and
- (c) an L* color measurement of at least 50 using the CIE 1976 L*a*b* scale on an LKE calorimeter.
A method of processing ESD dissipative ceramics comprising the steps of:
- (a) consolidating two or more powders to a final density by one or more heat treatments, and
- (b) using a final heat treatment to produce at least a 25% change in the resistivity of the resulting ceramic.
A method of forming light colored ESD dissipative ceramics comprising the steps of:
- (a) forming a mixture comprising from about 85 to 60 vol. % Y-TZP and from about 15 to 40 vol. % ZnO;
- and
- (b) densifying the mixture to at least 95% of the theoretical density by a primary heat treatment.
A method of forming light colored ESD dissipative ceramics comprising the steps of:
- (a) forming a mixture comprising from about 90 to 50 vol. % Y-TZP and from about 10 to 50 vol. % semi-conductive SnO2;
- and
- (b) densifying the mixture to at least 95% of the theoretical density by a primary heat treatment.
A method of modifying the resistivity of ESD dissipative ceramics comprising the step of hot isostatic pressing said ceramics under controlled conditions of heat and atmosphere.
A method of forming ceramic-based components for ESD-dissipative purposes comprising the steps of:
- (a) forming an ESD dissipative ceramic composition;
- (b) forming the desired surface finish on said ceramic composition;
- and
- (c) forming ceramic-based components either in whole or in part, in which the ceramics produce less than 600 particles/cm2 in the particle generation test for ESD-dissipative purposes.
A electrical sensing element formed at least in part from a zirconia-base structural ceramic having a strength of at least 400 MPa, said ceramic further comprising at least 10 vol % ZrO2, wherein electrical conductivity of the ceramic is provided by an additive present as a non-zirconia phase.
A nonmagnetic ESD dissipative ceramic composition formed by sintering a mixture comprising a base material and one or more nonmagnetic resistivity modifiers;
- wherein the base material comprises a tetragonal zirconia polycrystal (TZP);
- wherein the resistivity modifier comprises from about 5 vol. % to 60 vol. % of the base material;
- and wherein the ESD dissipative ceramic composition has the following physical properties:
- (a) volume resistivity ranging from 106-109 Ohm-cm;
- (b) flexural strength of at least 400 MPa;
- and
- (c) a residual flux density no greater than about 10 Gauss.
Dependencies are inferred from the claim text.