Method and system for forming electrically conductive pathways

Abstract

A system and two methods for forming electrically conductive pathways. These pathways can be connected with a microchip in order to form a radio frequency identification tag. A first method uses a thermal transfer ribbon, coated with a conductive material that is engaged with a receiver substrate. A thermal print head will heat a composition on the thermal transfer ribbon in order to transfer it to the receiver substrate. This transfer composition forms the electrically conductive pathway or antenna. In an alternative method, a receiver substrate is heated in order to react conductive material thereon. This receiver substrate is also heated by a thermal print head to form an electrically conductive pathway.

1 . A method of forming electrically conductive pathways, comprising the steps of: 
 providing a substrate coated with reactive material;    moving the substrate past a heat source;    selectively heating portions of the substrate with the heat source; and    developing the reactive material on the substrate during exposure to heat from the heat source to develop a desired pattern on the substrate, the reactive material forming an electrically conductive material.    
   
   
       2 . The method of forming electrically conductive pathways as recited in  claim 1 , further comprising the steps of: 
 using a cellulosic material, a polymeric film or paper as the substrate;    coating the substrate with the conductive material and with at least one of binders, surfactants and dispersants, the conductive material being a reducible material.    
   
   
       3 . The method of forming electrically conductive pathways as recited in  claim 2 , further comprising the step of using at least one of sorbitol copper formate, copper sulfate, cuprite, tenorite and silver nitrate as reactive material which forms the electrically conductive material.  
   
   
       4 . The method of forming electrically conductive pathways as recited in  claim 2 , further comprising the step of using at least one of styrene butadiene copolymers, polyvinyl alcohols, starch, vinyl chloride polymers, vinyl acetate polymers and methyl cellulose as the binders of the substrate.  
   
   
       5 . The method of forming electrically conductive pathways as recited in  claim 1 , further comprising the step of using a thermal print head as the heat source.  
   
   
       6 . The method of forming electrically conductive pathways as recited in  claim 1 , further comprising the step of combining the substrate with a microchip to form an antenna.  
   
   
       7 . The method of forming electrically conductive pathways as recited in  claim 6 , wherein the antenna is used as a radio frequency identification tag and further comprising the step of affixing the microchip to the receiver substrate either before or after the step of transferring the composition.  
   
   
       8 . A radio frequency tag produced according to the method of  claim 7 .  
   
   
       9 . A system for producing radio frequency tags comprising: 
 a conveyor for moving a substrate;    a thermal print head, the conveyor moving the substrate past the thermal print head, the thermal print head being selectively actuatable to heat a desired pattern on the substrate;    means on the substrate for reacting with the heat source to form electrically conductive pathways, the means including a heat sensitive composition on the substrate.    
   
   
       10 . The system for producing radio frequency tags as recited in  claim 9 , wherein the substrate is a thermal transfer ribbon and wherein the conveyor further conveys a receiver substrate past the heat source, the receiver substrate and the thermal transfer ribbon being engaged at the thermal print head and the heat sensitive composition being initially provided on the thermal transfer ribbon being heated in the desired pattern by the thermal print head and thereafter being transferred to the receiver substrate, the heat sensitive composition which is not heated by the thermal print head remaining on the thermal transfer ribbon, the heat sensitive composition transferred to the receiver substrate forming electrically conductive pathways on the receiver substrate.  
   
   
       11 . The system for producing radio frequency tags as recited in  claim 10 , further comprising a device for applying a microchip onto the receiver substrate with the electrically conductive pathways to form a radio frequency tag.  
   
   
       12 . The system for producing radio frequency tags as recited in  claim 9 , wherein the heat sensitive composition on the substrate includes at least one of metallic inks, metallic substances, metallic salts, metallic dispersions and carbon based inks.  
   
   
       13 . The system for producing radio frequency tags as recited in  claim 9 , wherein the heat sensitive composition on the substrate is at least one of sorbitol copper formate, copper sulfate, cuprite, tenorite and silver nitrate and wherein the thermal print head only reacts with the heat sensitive composition in the desired pattern to form the electrically conductive pathways with the reacted heat sensitive composition while unreacted heat sensitive composition remains on the substrate.  
   
   
       14 . The system for producing radio frequency tags as recited in  claim 13 , further comprising a device for applying a microchip onto the receiver substrate with the electrically conductive pathways to form a radio frequency tag.  
   
   
       15 . A radio frequency tag produced by the steps of: 
 providing a thermal transfer ribbon;    moving the thermal transfer ribbon past a heat source;    engaging the thermal transfer ribbon with a receiver substrate as the thermal transfer ribbon moves past the heat source;    selectively heating portions of the thermal transfer ribbon with the heat source; and    transferring a composition from the thermal transfer ribbon to the receiver substrate, the selective heating enabling a desired pattern of the composition to be transferred to the receiver substrate, the composition including an electrically conductive material.    
   
   
       16 . A method of forming electrically conductive pathways for radio frequency tags, comprising the steps of: 
 providing a thermal transfer ribbon including a precursor which is nonconductive;    moving the thermal transfer ribbon past a heat source;    engaging the thermal transfer ribbon with a flexible receiver substrate as the thermal transfer ribbon moves past the heat source;    using paper or pliable film as the receiver substrate;    selectively heating portions of the thermal transfer ribbon with the heat source to activate said nonconductive precursor to form an electrically conductive material; and    transferring a composition from the thermal transfer ribbon to the receiver substrate, the selective heating    enabling a desired pattern of the composition to be transferred to the paper or film receiver substrate, the composition transferred from the thermal transfer ribbon being an electrically conductive material.