Microwave-absorbing form-in-place paste

Abstract

A microwave-absorbing material which can be dispensed from standard form-in-place dispensing equipment combines a liquid resin system with a magnetic or lossy dielectric filler. In a preferred embodiment, the liquid resin system is a silicone resin system and the magnetic filler is iron carbonyl powder. The microwave-absorbing material is dispensed into a housing for electronic equipment. It may be dispensed into a cavity in the housing where it self-levels and cures. Alternatively, it may be dispensed onto a surface in the housing where, because of its thixotropic properties, it holds its shape and forms a pad of cured microwave-absorbing material thereon.

1 . A microwave-absorbing material comprising a liquid resin system and a magnetic or lossy dielectric filler.  
   
   
       2 . A microwave-absorbing material as claimed in  claim 1  wherein said liquid resin system is selected from the group consisting of silicone, urethane and epoxy resin systems.  
   
   
       3 . A microwave-absorbing material as claimed in  claim 1  wherein said liquid resin system is an organic resin system.  
   
   
       4 . A microwave-absorbing material as claimed in  claim 1  wherein said magnetic filler is selected from the group consisting of iron carbonyl; iron powder; iron silicide; ferrite; an alloy of nickel and iron; an alloy of iron, silicon and aluminum; carbon; fibers; and other fillers with electromagnetic (EM) properties.  
   
   
       5 . A microwave-absorbing material as claimed in  claim 1  wherein said liquid resin system is a silicone resin system and said magnetic filler is iron carbonyl powder.  
   
   
       6 . A method for absorbing radio-frequency (RF) emissions in electronic equipment, said method comprising the steps of: 
 providing a liquid resin system;    dispensing a magnetic or lossy dielectric filler in said liquid resin system;    dispensing said liquid resin system having said filler into a housing for said electronic equipment; and    curing said liquid resin system having said filler thereby forming a radio-frequency (RF) absorbing pad in said housing.    
   
   
       7 . A method as claimed in  claim 6  wherein said liquid resin system having said filler is self-leveling and is dispensed into a cavity in said housing.  
   
   
       8 . A method as claimed in  claim 6  wherein said liquid resin system having said filler has thixotropic properties and is dispensed onto a surface in said housing.