Patents by Inventor Krishna G. Sachdev
Krishna G. Sachdev 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).
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Patent number: 6503874Abstract: This invention provides a method for removing flux residue and similar other residues formed on the surfaces of micro electronic components during soldering operations using solder paste and fluxing agents in electronic module assembly component fabrication by a semi-aqueous solvent cleaning process using propylene glycol alkyl ether solvents, preferably the mono alkyl ethers, as replacements for xylene. The electronic components may contain plastic components, for example, a plastic grid array (PBGA) in addition to silicon device chip(s), C4 decaps and SMTs on a ceramic chip carrier with solder columns. Preferred solvents are dipropylene glycol mono methyl ether and tripropylene glycol mono methyl ether, which are both water soluble.Type: GrantFiled: January 16, 2001Date of Patent: January 7, 2003Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, Chon C. Lei
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Publication number: 20020127406Abstract: The invention is directed to improved conductive adhesives for solder-free interconnections in microelectronic assembly processes such as for chip carrier-to-substrate attachment. These adhesives are characterized by low tensile modulus, low resistivity, high adhesion strength, and durability of these properties during reliability stress conditions of thermal shock, thermal aging, and temperature/humidity (85° C./85%) exposure of the assembled devices. The adhesives contain a homogeneous solution of a siloxane containing epoxide, a curing agent, a curing catalyst and an organic polymeric or oligomeric additive. A conductive filler is added to the solution forming the filler. Preferred fillers are Ag coated with Pd and Ag coated with Au.Type: ApplicationFiled: January 11, 2001Publication date: September 12, 2002Applicant: International Business Machines CorporationInventors: Krishna G. Sachdev, Raymond A. Jackson, Amy B. Ostrander, Charles H. Perry, Megan J. Shannon
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Patent number: 6426007Abstract: This invention provides a method for treating waste water containing organic bases such as tetramethyl ammonium hydroxide and dissolved metals such as Mo, W, Cu and Ni which are generated from mask cleaning and Mo etching processes. The organic base along with Cu and Ni is first removed preferably by passing the effluent through a cation exchange resin followed by passing the cation exchanged effluent through an anion exchange resin to remove the Mo and W metals. The treated waste water meets federal guidelines for dissolved metal contaminant limits for water discharge to water ways. Alternatively, filtered effluent is directly passed through an anion exchange resin to remove Mo and W and the dissolved TMAH and copper and nickel are removed by cation exchange.Type: GrantFiled: April 29, 1999Date of Patent: July 30, 2002Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, Umar M. Ahmad
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Publication number: 20020094940Abstract: This invention provides a method for removing flux residue and similar other residues formed on the surfaces of microelectronic components during soldering operations using solder paste and fluxing agents in electronic module assembly component fabrication by a semi-aqueous solvent cleaning process using propylene glycol alkyl ether solvents, preferably the mono alkyl ethers, as replacements for xylene. The electronic components may contain plastic components, for example, a plastic grid array (PBGA) in addition to silicon device chip(s), C4 decaps and SMTs on a ceramic chip carrier with solder columns. Preferred solvents are dipropylene glycol mono methyl ether and tripropylene glycol mono methyl ether, which are both water soluble.Type: ApplicationFiled: January 16, 2001Publication date: July 18, 2002Applicant: International Business Machines CorporationInventors: Krishna G. Sachdev, Chon C. Lei
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Patent number: 6406778Abstract: The present invention relates generally to using at least one green sheet that is originally very thin with the help of at least one thicker green sheet. An adhesion barrier to build multi-layer ceramic laminates and process thereof is also disclosed. Basically, the present invention relates to a structure and method for forming laminated structures and more particularly to a structure and method for fabricating multi-density, multi-layer ceramic products using at least one very thin green sheet and/or at least one green sheet with very dense electrically conductive patterns on top of at least one thicker green sheet.Type: GrantFiled: July 21, 2000Date of Patent: June 18, 2002Assignee: International Business Machines CorporationInventors: Govindarajan Natarajan, Krishna G. Sachdev, Abubaker S. Shagan
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Publication number: 20020072482Abstract: An aqueous alkaline cleaning composition for efficient removal of Mo, Cu, W, or Cu/Ni-based conductive paste residue from screening masks, associated screening equipment and the like by using alkali metal salt and/or tetramethyl ammonium salt of polyacrylic acid, acrylic acid-methacrylic acid co-polymer, polyaspartic acid, polylactic acid, poly(acrylic acid-co-maleic anhydride), poly(maleic acid), with excess alkali for pH adjustment in the range of about 11.5-13.5, and a surfactant which may be a medium foam, low foam or no-foam surfactant, and is preferably an amphoteric and/or non-ionic and/or ionic surfactant.Type: ApplicationFiled: December 7, 2000Publication date: June 13, 2002Inventors: Krishna G. Sachdev, Glenn A. Pomerantz, Daniel S. Mackin
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Patent number: 6351871Abstract: This invention relates to the cleaning of objects that relate to semiconductor printing, such as, for example, screening masks. This invention is basically directed to removing, for example, an organic polymer-metal composite paste from screening masks used in printing conductive metal patterns onto ceramic green sheets in the fabrication of semiconductor packaging substrates. More particularly, this invention is concerned with the automated in-line cleaning of paste screening masks with an aqueous alkaline solution of a quaternary ammonium hydroxide as a more environmentally friendly alternative to non-aqueous organic solvents-based cleaning in screening operations for the production multilayer ceramic (MLC) substrates.Type: GrantFiled: June 17, 1999Date of Patent: March 5, 2002Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, John T. Butler, Michael E. Cropp, Donald W. DiAngelo, John F. Harmuth, James N. Humenik, John U. Knickerbocker, Daniel S. Mackin, Glenn A. Pomerantz, David E. Speed, Candace A. Sullivan, Bruce E. Tripp, James C. Utter
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Publication number: 20020000239Abstract: A stripping composition and a method of using the stripping composition to remove cured resins such as elastomeric silicone adhesive deposits from ceramic and metal surfaces of electronic modules to provide reworkability options in assembly processes including diagnostic parts, parts replacement and recovery of substrates from test vehicles is provided. The stripping compositions comprise a base preferably an organic base such as a quaternary ammonium hydroxide, a surfactant and a high boiling environmentally and chemically safe solvent such as di- or tri-propylene glycol alkyl ether. In another stripping composition, the base is used in combination with a mixture of N-alkyl pyrrolidone components, preferably an N-alkyl pyrrolidone and a N-cycloalkyl pyrrolidone. The stripping compositions are used to contact an electronic module having a cured resin such as a silicone adhesive residue deposit on the module surface to dissolve, remove or strip the deposit.Type: ApplicationFiled: September 27, 1999Publication date: January 3, 2002Inventors: KRISHNA G. SACHDEV, UMAR M. AHMAD, FAREED Y. AUDI, DANIEL G. BERGER, JOHN U. KNICKERBOCKER, CHON C. LEI
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Publication number: 20010039251Abstract: This invention relates to cleaning organic polymer-metal composite material from screening masks and associated accessories used for printing a conductive paste pattern on microelectronic components, such as, for example, ceramic green sheets in the production of semiconductor packaging substrates. More particularly, this invention is concerned with the aqueous cleaning of screening paste residue from masks and other paste screening and processing equipment using water-based alkaline cleaning compositions comprising an organic quaternary ammonium hydroxide as the primary basic active ingredient to provide a more environmentally friendly alternative to non-aqueous organic solvents-based cleaning.Type: ApplicationFiled: June 12, 1998Publication date: November 8, 2001Inventors: KRISHNA G. SACHDEV, JAMES N. HUMENIK, JOHN U. KNICKERBOCKER, GLENN A. POMERANTZ
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Patent number: 6280527Abstract: This invention relates to the cleaning of objects that relate to semiconductor printing, such as, for example, screening masks. This invention is basically directed to removing, for example, an organic polymer-metal composite paste from screening masks used in printing conductive metal patterns onto ceramic green sheets in the fabrication of semiconductor packaging substrates. More particularly, this invention is concerned with the automated in-line cleaning of paste screening masks with an aqueous alkaline solution of a quaternary ammonium hydroxide as a more environmentally friendly alternative to non-aqueous organic solvents-based cleaning in screening operations for the production multilayer ceramic (MLC) substrates.Type: GrantFiled: June 12, 1998Date of Patent: August 28, 2001Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, John T. Butler, Michael E. Cropp, Donald W. DiAngelo, John F. Harmuth, James N. Humenik, John U. Knickerbocker, Daniel S. Mackin, Glenn A. Pomerantz, David E. Speed, Candace A. Sullivan, Bruce E. Tripp, James C. Utter
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Patent number: 6277799Abstract: This invention relates to an aqueous cleaning method for removal of metal-organic composite paste residue from the surface of components, such as, screening masks, associated paste screening equipment, substrates, to name a few. The invention is particularly concerned with aqueous alkaline cleaning solutions comprising alkali metal salt and/or quaternary ammonium salt of an organic acid preferably &agr;-hydroxy carboxylic acid in the presence of excess alkali and optionally a surface active agent for use in cleaning components, such as, screening masks, associated screening equipment, substrates, etc., which are used in the production of electronic components.Type: GrantFiled: June 25, 1999Date of Patent: August 21, 2001Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, James N. Humenik, John U. Knickerbocker, Glenn A. Pomerantz
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Patent number: 6262390Abstract: A method to repair Aluminum Nitride (AlN) substrates is disclosed wherein a frequency doubled Q-switched Nd:YAG laser is used to remove unwanted metallurgy. The substrate is place in a liquid filled work chamber which acts to prevent metallic species of AlN from forming. The repair site can be sealed with a novel polymer coating to prevent contamination or corrosion. Repairs can be made to buried or surface metallurgy.Type: GrantFiled: December 14, 1998Date of Patent: July 17, 2001Assignee: International Business Machines CorporationInventors: David B. Goland, Mark J. LaPlante, David C. Long, Dale C. McHerron, Krishna G. Sachdev, Subhash L. Shinde
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Patent number: 6261927Abstract: This invention relates generally to a new method of forming semiconductor substrates with defect-free surface metallurgical features. In particular, the invention related to a method for providing surface protected ceramic green sheet laminates using at least one thermally depolymerizable surface layer. More particularly, the invention encompasses a method for fabricating semiconductor substrates wherein a thermally depolymerizable/decomposable surface film is placed over a ceramic green sheet stack or assembly prior to lamination and caused to conform to the surface topography of the green sheet during lamination. The invention also encompasses a method for fabricating surface protected green sheet laminates which can be sized or diced without causing process related defects on the ceramic surface.Type: GrantFiled: April 30, 1999Date of Patent: July 17, 2001Assignee: International Business Machines CorporationInventors: Govindarajan Natarajan, Richard F. Indyk, Vincent P. Peterson, Krishna G. Sachdev
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Patent number: 6245171Abstract: The present invention relates generally to using at least one green sheet that is originally very thin with the help of at least one thicker green sheet. An adhesion barrier to build multi-layer ceramic laminates and process thereof is also disclosed. Basically, the present invention relates to a structure and method for forming laminated structures and more particularly to a structure and method for fabricating multi-density, multi-layer ceramic products using at least one very thin green sheet and/or at least one green sheet with very dense electrically conductive patterns on top of at least one thicker green sheet.Type: GrantFiled: November 23, 1998Date of Patent: June 12, 2001Assignee: International Business Machines CorporationInventors: Govindarajan Natarajan, Krishna G. Sachdev, Abubaker S. Shagan
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Patent number: 6221269Abstract: A method is provided for etching and removing extraneous molybdenum or debris on ceramic substrates such as semiconductor devices and also for molybdenum etching in the fabrication of molybdenum photomasks. The method employs a multi-step process using an acidic aqueous solution of a ferric salt to remove (etch) the molybdenum debris followed by contacting the treated substrate with an organic quaternary ammonium hydroxide to remove any molybdenum black oxides which may have formed on the exposed surface of treated molybdenum features in ceramic substrates. The method is environmentally safe and the waste solutions may be easily waste treated for example by precipitating the ferric salts as ferric hydroxide and removing anions such as sulfate by precipitation with lime. The method replaces the currently used method of employing ferricyanide salts which create serious hazardous waste disposal and environmental problems.Type: GrantFiled: January 19, 1999Date of Patent: April 24, 2001Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, Umar M. Ahmad, Hsing H. Chen, Lawrence D. David, Charles H. Perry, Donald R. Wall
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Patent number: 6032683Abstract: A cleaning method and related apparatus for cleaning semiconductor screening masks using an aqueous alkali detergent solution applied under high pressure simultaneously from both sides of the mask, followed by a drying step that uses air knives to blow off the mask surface any residual cleaner solution.Type: GrantFiled: February 26, 1999Date of Patent: March 7, 2000Assignee: International Business Machines CorporationInventors: Jon A. Casey, Michael E. Cropp, Donald W. DiAngelo, John F. Harmuth, John U. Knickerbocker, David C. Long, Daniel S. Mackin, Glenn A. Pomerantz, Krishna G. Sachdev, David E. Speed, Candace A. Sullivan, Robert J. Sullivan, Bruce E. Tripp, James C. Utter
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Patent number: 5938856Abstract: This invention relates to the use of non-halogenated and non-aromatic cleaning solvents as environmentally safe replacement of perchloroethylene and xylene to remove rosin flux residue formed on electronic circuit device materials during solder interconnection process for assembly of electronic components.Type: GrantFiled: June 13, 1997Date of Patent: August 17, 1999Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, Umar M. Ahmad, John U. Knickerbocker, Chon C. Lei
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Patent number: 5916374Abstract: A cleaning method and related apparatus for cleaning semiconductor screening masks using an aqueous alkali detergent solution applied under high pressure simultaneously from both sides of the mask, followed by a drying step that uses air knives to blow off the mask surface any residual cleaner solution.Type: GrantFiled: February 9, 1998Date of Patent: June 29, 1999Assignee: International Business Machines CorporationInventors: Jon A. Casey, Michael E. Cropp, Donald W. DiAngelo, John F. Harmuth, John U. Knickerbocker, David C. Long, Daniel S. Mackin, Glenn A. Pomerantz, Krishna G. Sachdev, David E. Speed, Candace A. Sullivan, Robert J. Sullivan, Bruce E. Tripp, James C. Utter
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Patent number: 5888308Abstract: This invention relates to the use of water-based cleaning solutions and their use as environmentally safe replacements of chlorinated hydrocarbon solvents to remove metal-polymer composite paste residue from screening masks and ancillary equipment, such as, used for screening a conductive metal pattern on a ceramic green sheet in the manufacture of multi-layer ceramic products.Type: GrantFiled: February 28, 1997Date of Patent: March 30, 1999Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, John U. Knickerbocker, Glenn A. Pomerantz, Bruce E. Tripp
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Patent number: 5700581Abstract: The present invention discloses chip (die) bond adhesive formulations preferably comprising a siloxane containing epoxide preferably a diglycidyl ether derivative, an anhydride curing additive which is soluble in the epoxide without the use of a solvent, and, optionally comprising, and oligomeric/polymeric co-additive of the type poly(alkylacrylate or -methacrylate), in conjunction with thermal and electrically conductive fillers and conventional co-catalysts used for curing epoxy systems to provide reworkable epoxy adhesives. Also disclosed are adhesive formulations comprising a siloxane containing epoxide and a hydroxybenzophenone curing additive which is soluble in the epoxide without the use of a solvent. The chips can be bonded to the substrate by conventional heating and curing techniques. With epoxy adhesive compositions comprising polyacrylate additives, the die bonded assembly can be reworked by heating the assembly to about 180.degree. C. to 250.degree. C.Type: GrantFiled: June 26, 1996Date of Patent: December 23, 1997Assignee: International Business Machines CorporationInventors: Krishna G. Sachdev, Michael Berger, Mark S. Chace