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Method of forming conductors at low temperatures using metallic nanocrystals and productRelated Patent Categories: Specialized Metallurgical Processes, Compositions For Use Therein, Consolidated Metal Powder Compositions, And Loose Metal Particulate Mixtures, Processes, Producing Or Purifying Free Metal Powder Or Producing Or Purifying Alloys In Powder Form (i.e., Named Or Of Size Up To 1,000 Microns In Its Largest Dimension), Decomposition Of Organo-compound Containing Metal Or Metal CarbonylMethod of forming conductors at low temperatures using metallic nanocrystals and product description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070175296, Method of forming conductors at low temperatures using metallic nanocrystals and product. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This is a continuation-in-part of Serial No. PCT/US2004/005161, filed Feb. 19, 2004, the priority of which is claimed under 35 USC 120 and 365(c), which is incorporated by reference herein in its entirety. Priority is claimed pursuant to 35 USC 119(e) and 365(c) of provisional application Ser. No. 60/449,191, filed Feb. 20, 2003, which is incorporated by reference herein in its entirety. BACKGROUND OF THE INVENTION [0002] This invention is directed to forming conducting metallic films using organic-encapsulated metallic nanoparticles deposited out of a solution or suspension and more particularly the invention is directed to a method of forming metallic nanocrystals or particles for use in forming the metallic film. [0003] There has been growing interest in the development of printed organic electronics technologies, which are expected to see use in low-cost, flexible displays and disposable electronics applications. Low-cost RFID (radio frequency identification) tags are considered to be a compelling application, since they may be used to replace UPC (Universal Product Code) barcodes on consumer products, ushering in an era of enhanced consumer convenience and warehousing efficiency, through a realization of real-time price and product controls, automated inventory processes, and automated checkout. [0004] All-printed circuit technologies are attractive for several reasons. They eliminate the need for expensive lithography, and also eliminate the need for high-vacuum processing, including PVD, CVD, plasma etching, etc., all of which have major impacts on system cost. Additionally, they use an additive fabrication process, which reduces the waste abatement costs. Thus, they are expected to result in a substantially reduced integrated cost making them suitable for use in disposable consumer products. [0005] Metallic nanoparticle conductors are technologically important as means of interconnecting and contacting semiconducting devices, as well as in the formation of such passive electronic components as inductors, capacitors, wires, and antennae. Solution or suspension deposited conductors are of interest since the may potentially be deposited using such low cost means as inkjet printing, screen printing, offset printing, etc. In particular, for use in low-cost applications such as RFID tags, displays, etc., on plastic, it is crucial that the entire process, including the post-deposit annealing of the nanoparticles, should be performed at plastic-compatible temperatures, .about.150.degree. C. or so. Metallic nanoparticles have been formed using precipitation reactions performed in a solution containing organic encapsulant molecules. As the metal precipitates out of solution/suspension, it is rapidly encapsulated by the organic molecules to form an organic-encapsulated metallic nanoparticle. Nanoparticles have been reported using numerous metals including gold, silver, palladium, platinum, copper. The encapsulation is achieved by using an organic molecule chosen such that it preferentially attaches to the metal surface to form a thin layer around the particle. For example, thiol-terminated molecules such as alkanethiols are used to coat gold nanoparticles, and amine-terminated molecules such as alkaneamines are used to coat copper nanoparticles. [0006] To form conductor films out of solution/suspension, the nanoparticles are dissolved/suspended in a solvent, typically, an organic solvent or even water, depending on the organic encapsulant. For example, alkane-coated particles dissolve in solvents from the toluene and terpineol families. The solution/suspension is deposited on the surface of a substrate to be coated using such means as pipetting, inkjet printing, screen printing, etc. The solvent evaporates, leaving behind the organic-coated nanoparticle. The substrate is annealed by exposure to an elevated temperature, causing the evaporation of the organic material, followed by sintering/melting of the nanoparticle. [0007] Conductors formed using this technique have been reported in the past. However, the annealing temperature of these conductors has been quite high (200.degree. C.-400.degree. C.), which is not compatible with plastic substrates. SUMMARY OF THE INVENTION [0008] In accordance with the invention, metallic nanoparticles are provided which can be used in forming metallic film conductors at reduced temperatures compatible with plastic carriers for the film conductors. [0009] This is achieved by selecting the molecular weight of the organic encapsulant of the nanoparticle such that it can be evaporated at temperatures compatible with plastic substrates. Accordingly, a method of forming an electrical conductor pattern from metallic nanoparticles at temperatures below the melting point of plastic is provided comprising the steps of: [0010] a) depositing a composition comprising organic molecule encapsulated metallic nanoparticles and a solvent in a predetermined pattern onto a substrate; [0011] b) evaporating the solvent; [0012] c) annealing the encapsulated metallic nanoparticles to evaporate the organic molecules, and [0013] d) sintering or melting said metallic nanoparticles to form the electrical conductor pattern; [0014] wherein the organic molecule has a molecular weight that permits step (c) to be conducted at a temperature below the melting point of plastic at atmospheric pressure. [0015] Further, the sintering or melting temperature of the metallic nanoparticle is lowered by use of a smaller particle, thereby increasing the particle surface area relative to the particle volume. Accordingly, a method of forming an electrical conductor pattern from metallic nanoparticles at temperatures below the melting point of plastic is provided comprising the steps of: [0016] a) depositing a composition comprising organic molecule encapsulated metallic nanoparticles and a solvent in a predetermined pattern onto a substrate; [0017] b) evaporating the solvent; [0018] c) annealing said encapsulated metallic nanoparticles to evaporate the organic molecules, and [0019] d) sintering or melting said metallic nanoparticles to form the electrical conductor pattern; [0020] wherein the metallic nanoparticles have a particle average maximum dimension that permits step (d) to be conducted at a temperature below the melting point of plastic at atmospheric pressure. [0021] A metallic nanoparticle composition compatible for use in printing low resistance conductors on a plastic base is provided comprising organic molecule encapsulated metallic nanoparticles wherein the organic molecule has a molecular weight that permits evaporated of the organic molecules after deposition of the composition onto a substrate at a temperature below the melting point of plastic at atmospheric pressure. Continue reading about Method of forming conductors at low temperatures using metallic nanocrystals and product... Full patent description for Method of forming conductors at low temperatures using metallic nanocrystals and product Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method of forming conductors at low temperatures using metallic nanocrystals and product patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method of forming conductors at low temperatures using metallic nanocrystals and product or other areas of interest. ### Previous Patent Application: Extension housing to transmission case attachment Next Patent Application: Launder burner Industry Class: Specialized metallurgical processes, compositions for use therein, consolidated metal powder compositions, and loose metal particulate mixtures ### FreshPatents.com Support Thank you for viewing the Method of forming conductors at low temperatures using metallic nanocrystals and product patent info. IP-related news and info Results in 0.15009 seconds Other interesting Feshpatents.com categories: Tyco , Unilever , Warner-lambert , 3m 174 |
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