Selective metal removal process for metallized retro-reflective and holographic films and radio frequency devices made therewith

Abstract

A method for selectively removing metal from a metallized substrate (e.g., a metallized polymer film) and the formation of devices thereby are provided. The method involves selectively exposing the metallized surface to a demetallizing (i.e., an oxidizing) chemical solution. The metallized layer can be selectively exposed to the demetallizing solution using a flexographic printing process wherein printing rollers are used to transfer the demetallizing solution to the metallized surface. An identification device including, for example, a holographic, retro-reflective, or other metallized material and a radio-frequency transponder are also provided. The radio-frequency transponder includes an RF chip and an antenna in electrical communication with the chip. The identification device including the holographic image allows both electronic identification through the reading of identification data stored in the chip and optical identification via the holographic image.

1 . An identification device, comprising: 
 a base layer;    a radio-frequency (RF) transponder comprising an RF chip and an antenna disposed on the base layer, wherein the antenna is in electrical communication with the chip; and    a metallized region;    wherein the metallized region has been selectively demetallized, such that the RF transponder is able to transmit and receive information.    
   
   
       2 . The device of  claim 1 , wherein the metallized region includes an image.  
   
   
       3 . The device of  claim 2 , wherein the image is a holographic image.  
   
   
       4 . The device of  claim 1 , wherein the metallized region includes a retro-reflective layer.  
   
   
       5 . The device of  claim 1 , wherein the metallized region comprises a holographic image and wherein the holographic image and the antenna form a single metal layer.  
   
   
       6 . The device of  claim 1 , wherein the base layer has at least one side, and wherein the antenna and the metallized region are located on the same side of the base layer.  
   
   
       7 . The device of  claim 1 , wherein the base layer has at least a first side and a second side, the first side being opposite the second side, and wherein the antenna and the metallized region are located on opposite sides of the base layer.  
   
   
       8 . The device of  claim 1 , wherein the base layer has at least a first side and a second side, the first side being opposite the second side, and wherein a first part of the antenna and the metallized region are located on the first side, and a second part of the antenna is located on the second side of the base layer, and wherein the first part of the antenna is electrically connected to the second part of the antenna.  
   
   
       9 . The device of  claim 1 , wherein the device comprises an upper metal layer positioned above the base layer and a lower metal layer positioned below the base layer, wherein a first part of the antenna is formed on the upper metal layer and a second part of the antenna is formed on the lower metal layer, the device further comprising a through contact connecting the first part of the antenna to the second part of the antenna.  
   
   
       10 . The device of  claim 1 , wherein the metallized region is in electrical communication with the antenna.  
   
   
       11 . The device of  claim 10 , wherein the metallized region comprises an electronic commutation element.  
   
   
       12 . The device of  claim 10 , wherein the metallized region comprises a capacitor.  
   
   
       13 . The device of  claim 1 , wherein the metallized region comprises a plurality of electrically isolated holographic regions.  
   
   
       14 . The device of  claim 1 , wherein the base layer is an electrically conductive layer.  
   
   
       15 . The device of  claim 14 , wherein an isolation layer is formed on the base layer.  
   
   
       16 . The device of  claim 15 , wherein the radio frequency (RF) chip is mounted on the isolation layer.  
   
   
       17 . The device of  claim 15 , wherein the base layer includes a depressed region, and wherein the isolation layer is formed in the depressed region.  
   
   
       18 . The device of  claim 1 , wherein the base layer has at least one side, and wherein the antenna and the metallized region are formed on the same side of the base layer in discrete, non-overlapping areas.  
   
   
       19 . The device of  claim 1 , wherein the antenna comprises a conductive wire inlaid in a polymer layer.  
   
   
       20 . The device of  claim 1 , wherein the device is selected from the group consisting of a decal, a license plate, and an identification card.  
   
   
       21 . The device of  claim 1 , wherein the metallized region has been selectively demetallized in a square grid pattern.  
   
   
       22 . The device of  claim 21 , wherein the squares in the square grid pattern have a length of about  5  mm or less.  
   
   
       23 . The device of  claim 21 , wherein the squares in the square grid pattern have a length of about  3  mm or less.  
   
   
       24 . A method of forming a pattern in a metallized region, the method comprising: 
 transferring a metal etching solution to portions of an exposed surface of the metallized region using a printing process;    allowing the etching solution to react with the metallized region to selectively demetallize the surface; and    washing the selectively demetallized surface.    
   
   
       25 . The method of  claim 24 , wherein the printing process is selected from the group consisting of a flexographic printing process, an offset printing process and a screen printing process.  
   
   
       26 . The method of  claim 24 , wherein the metal etching solution is an aqueous solution of sodium hydroxide.  
   
   
       27 . The method of  claim 26 , wherein the metal etching solution further comprises ethylene glycol.