Electrostatic discharge device and method for manufacturing the same

Abstract

The invention is achieved by applying a layer of the mixture that contains polymer and conductive particles over a first surface, when the mixture has a first viscosity that allows the conductive particles to rearrange within the layer. An electric field is applied over the layer, so that a number of the conductive particles are aligned with the field and thereafter the viscosity of the layer is changed to a second, higher viscosity, in order to mechanically stabilise the layer. This leads to a stable layer with enhanced and anisotropic conductivity that can be used in the manufacture of ESD devices.

1 . A method for manufacturing an ESD device forming at least one anisotropic conductive or dissipative layer comprising a mixture of a nonconductive matrix and conductive particles characterised by
 a. applying a layer of the mixture over a first surface of the ESD device, the mixture having a first viscosity which allows the conductive particles to rearrange within the layer;   b. applying an electric field between two alignment electrodes over the layer, so that a number of the conductive particles are aligned with the field, thus creating conductive pathways;   c. changing the viscosity of the layer to a second viscosity, said second viscosity being higher than the first viscosity in order to mechanically stabilise the layer and preserve the conductive pathways.   
     
     
         2 . A method in accordance with  claim 1 , characterised by that the matrix comprises one or more polymer. 
     
     
         3 . A method in accordance with  claim 2 , characterised by that the matrix is an adhesive. 
     
     
         4 . A method in accordance with  claim 1 , characterised by that at least one of the alignment electrodes is in direct contact with the layer. 
     
     
         5 . A method in accordance with  claim 1 , characterised by that the alignment electrodes are insulated from the layer. 
     
     
         6 . A method in accordance with  claim 1 , characterised by that the electric field is in the order of 0.05 to 20 kV/cm, or 0.05 to 5 kV/cm or 0.1 to 1 Kv and especially in the order of 0.1-1 kV/cm. 
     
     
         7 . A method in accordance with  claim 1 , characterised by that the electric field is an AC field. 
     
     
         8 . A method in accordance with  claim 1 , characterised by that the field is applied between the first surface and a second surface. 
     
     
         9 . (canceled) 
     
     
         10 . A method in accordance with  claim 1 , characterised by that the matrix is totally or partly removed from the layer after step c. 
     
     
         11 . A method in accordance with  claim 1 , characterised by that a concentration of the conductive particles in the layer is below percolation threshold. 
     
     
         12 . An ESD device comprising a conductive layer in accordance with  claim 1 . 
     
     
         13 . An ESD device in accordance with  claim 12  characterised by that the device comprises a conductive or dissipative sheet or floor tile. 
     
     
         14 . An ESD device in accordance with  claim 12  characterised by that the conductive particles comprises one or more of carbon black, carbon nanodiscs, carbon nanocones, metals, metal oxides and colloidal metal containing particles. 
     
     
         15 . An ESD device in accordance with  claim 12  characterised by that the matrix is a thermoplastic resin which includes one or more of polyurethane, polyvinyl chloride, polyolefins and copolymers of vinyl chloride and copolymers of olefins. 
     
     
         16 . An ESD device in accordance with  claim 12  characterised by that the electrically conducting or dissipative layer has a thickness from 0.1-5 mm, preferably less than 3 mm. 
     
     
         17 . An ESD device in accordance with  claim 12 , characterised by the device being a conductive film for packaging ESD-sensitive electronics. 
     
     
         18 . An ESD device in accordance with  claim 12  characterized by the device being an ESD gasket. 
     
     
         19 . An ESD device in accordance with  claim 12  characterized by the device being a sheet of up to 50 cm in thickness, preferably less than 5 cm thick and less than 10 m wide. 
     
     
         20 . An ESD device in accordance with  claim 12  characterized by the device being a sheet of up to 3 cm in thickness, preferably less than 2 cm thick and less than 10 m wide. 
     
     
         21 . An ESD device in accordance with  claim 12 , characterised by the device being a film for use in batteries or capacitors.