Patents by Inventor Alfred T. Walker

Alfred T. Walker has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Lead-free resistive composition
    Patent number: 8257619
    Abstract: A substantially lead-free thick-film resistor paste composition is disclosed including a resistor composition dispersed in an organic vehicle. The resistor composition includes (a) RuO2 conductive material; (b) an ?-oxide selected from CuO, Na2O, K2O, Li2O and combinations thereof (c) a borosilicate glass composition having: (i) B2O3, (ii) SiO2, (iii) a ?-oxide selected from BaO, CaO, ZnO, SrO, MgO and combinations thereof, and optionally including any of (iv) P2O5, (v) ZrO2 and (vi) Al2O3. The CuO ?-oxide and TiO2, Ta2O5, Nb2O5 ?-oxide(s) and combinations thereof are present in the paste composition either separately, or in the borosilicate glass composition, or both. The Na2O, K2O, Li2O ?-oxide(s) and combinations thereof are present in the borosilicate glass composition. TCR values in the range of +/?100 ppm/° C. and R values of 100 ohms to 10 mega-ohms per square are obtained by resistors made from the paste composition.
    Type: Grant
    Filed: April 16, 2009
    Date of Patent: September 4, 2012
    Assignee: E I du Pont de Nemours and Company
    Inventors: Marc H. Labranche, Kenneth Warren Hang, Alfred T. Walker, Constance Wenger, legal representative, Yuko Ogata
  • Non-lead resistor composition
    Patent number: 8226857
    Abstract: A non-lead composition for use as a thick-film resistor paste in electronic applications. The composition comprises particles of Li2RuO3 of diameter between 0.5 and 5 microns and a lead-free frit. The particles have had the lithium at or near primarily the surface of the particle at least partially exchanged for atoms of other metals.
    Type: Grant
    Filed: May 31, 2011
    Date of Patent: July 24, 2012
    Assignee: E. I. du Pont de Nemours and Company
    Inventors: Paul Douglas Vernooy, Alfred T. Walker, Kenneth Warren Hang
  • NON-LEAD RESISTOR COMPOSITION
    Publication number: 20110227003
    Abstract: A non-lead composition for use as a thick-film resistor paste in electronic applications. The composition comprises particles of Li2RuO3 of diameter between 0.5 and 5 microns and a lead-free frit. The particles have had the lithium at or near primarily the surface of the particle at least partially exchanged for atoms of other metals.
    Type: Application
    Filed: May 31, 2011
    Publication date: September 22, 2011
    Applicant: E.I. DU PONT DE NEMOURS AND COMPANY
    Inventors: PAUL DOUGLAS VERNOOY, Alfred T. Walker, Kenneth Warren Hang
  • Non-lead resistor composition
    Patent number: 7951311
    Abstract: A non-lead composition for use as a thick-film resistor paste in electronic applications. The composition comprises particles of Li2RuO3 of diameter between 0.5 and 5 microns and a lead-free frit. The particles have had the lithium at or near primarily the surface of the particle at least partially exchanged for atoms of other metals.
    Type: Grant
    Filed: October 23, 2009
    Date of Patent: May 31, 2011
    Assignee: E.I. du Pont de Nemours and Company
    Inventors: Paul Douglas Vernooy, Alfred T. Walker, Kenneth Warren Hang
  • LEAD-FREE RESISTIVE COMPOSITION
    Publication number: 20110089381
    Abstract: A substantially lead-free thick-film resistor paste composition is disclosed including a resistor composition dispersed in an organic vehicle. The resistor composition includes (a) RuO2 conductive material; (b) an ?-oxide selected from CuO, Na2O, K2O, Li2O and combinations thereof (c) a borosilicate glass composition having: (i) B2O3, (ii) SiO2, (iii) a ?-oxide selected from BaO, CaO, ZnO, SrO, MgO and combinations thereof, and optionally including any of (iv) P2O5, (v) ZrO2 and (vi) Al2O3. The CuO ?-oxide and TiO2, Ta2O5, Nb2O5 ?-oxide(s) and combinations thereof are present in the paste composition either separately, or in the borosilicate glass composition, or both. The Na2O, K2O, Li2O ?-oxide(s) and combinations thereof are present in the borosilicate glass composition. TCR values in the range of +/?100 ppm/° C. and R values of 100 ohms to 10 mega-ohms per square are obtained by resistors made from the paste composition.
    Type: Application
    Filed: April 16, 2009
    Publication date: April 21, 2011
    Applicant: E. I. DU PONT DE NEMOURS AND COMPANY
    Inventors: Marc H. Labranche, Kenneth Warren Hang, Alfred T. Walker, Constance Wenger, Yuko Ogata
  • NON-LEAD RESISTOR COMPOSITION
    Publication number: 20100040531
    Abstract: A non-lead composition for use as a thick-film resistor paste in electronic applications. The composition comprises particles of Li2RuO3 of diameter between 0.5 and 5 microns and a lead-free frit. The particles have had the lithium at or near primarily the surface of the particle at least partially exchanged for atoms of other metals.
    Type: Application
    Filed: October 23, 2009
    Publication date: February 18, 2010
    Applicant: E. I. DU PONT DE NEMOURS AND COMPANY
    Inventors: PAUL DOUGLAS VERNOOY, ALFRED T. WALKER, KENNETH WARREN HANG
  • Non-lead resistor composition
    Patent number: 7608206
    Abstract: A non-lead composition for use as a thick-film resistor paste in electronic applications. The composition comprises particles of Li2RuO3 of diameter between 0.5 and 5 microns and a lead-free frit. The particles have had the lithium at or near primarily the surface of the particle at least partially exchanged for atoms of other metals.
    Type: Grant
    Filed: April 18, 2008
    Date of Patent: October 27, 2009
    Assignee: E.I. duPont de Nemours & Company
    Inventors: Paul Douglas VerNooy, Alfred T. Walker, Kenneth Warren Hang
  • NON-LEAD RESISTOR COMPOSITION
    Publication number: 20090261306
    Abstract: A non-lead composition for use as a thick-film resistor paste in electronic applications. The composition comprises particles of Li2RuO3 of diameter between 0.5 and 5 microns and a lead-free frit. The particles have had the lithium at or near primarily the surface of the particle at least partially exchanged for atoms of other metals.
    Type: Application
    Filed: April 18, 2008
    Publication date: October 22, 2009
    Inventors: Paul Douglas VerNooy, Alfred T. Walker, Kenneth Warren Hang