Low signal loss bonding ply for multilayer circuit boards

Abstract

A low loss circuit board sheet includes a first layer disposed on a second layer. The first layer includes a thermosetting adhesive composition and the second layer is selected from a woven fabric substrate impregnated with at least one rubber, a nonwoven fabric substrate impregnated with at least one rubber and a polymeric film having at least one rubber disposed thereon.

1 . A low loss circuit board sheet comprising a first layer disposed on a second layer, said first layer comprising a thermosetting adhesive composition and said second layer selected from a woven fabric substrate impregnated with at least one rubber, a nonwoven fabric substrate impregnated with at least one rubber and a polymeric film having at least one rubber disposed thereon.  
     
     
         2 . A low loss circuit board sheet according to  claim 1 , wherein the second layer is a woven fabric substrate impregnated with at least one rubber.  
     
     
         3 . A low loss circuit board sheet according to  claim 1 , wherein the second layer is a nonwoven fabric substrate impregnated with at least one rubber.  
     
     
         4 . A low loss circuit board sheet according to  claim 1 , wherein the second layer is a polymeric film having at least one rubber disposed thereon.  
     
     
         5 . A low loss circuit board sheet according to  claim 1 , additionally comprising at least one metallization layer.  
     
     
         6 . A low loss circuit board sheet according to  claim 1 , wherein said thermosetting adhesive composition comprises an epoxy resin.  
     
     
         7 . A low loss circuit board sheet according to  claim 1 , wherein said thermosetting adhesive composition comprises a rubber.  
     
     
         8 . A low loss circuit board sheet according to  claim 1 , wherein the first layer or the second layer additionally comprises a ceramic filler.  
     
     
         9 . A low loss laminate comprising a plurality of low loss circuit board sheets laminated together by means of a thermosetting adhesive composition, wherein each of said low loss circuit board sheets comprises a first layer disposed on a second layer, said first layer comprising said thermosetting adhesive composition and said second layer selected from a woven fabric substrate impregnated with at least one rubber, a nonwoven fabric substrate impregnated with at least one rubber and a polymeric film having at least one rubber disposed thereon.  
     
     
         10 . A low loss laminate according to  claim 9  wherein the second layer is a woven fabric substrate impregnated with at least one rubber.  
     
     
         11 . A low loss laminate according to  claim 9 , wherein the second layer is a nonwoven fabric substrate impregnated with at least one rubber.  
     
     
         12 . A low loss laminate according to  claim 9 , wherein the second layer is a polymeric film having at least one rubber disposed thereon.  
     
     
         13 . A low loss laminate according to  claim 9 , additionally comprising at least one metallization layer.  
     
     
         14 . A low loss laminate according to  claim 9 , wherein said thermosetting adhesive composition comprises an epoxy resin.  
     
     
         15 . A low loss laminate according to  claim 9 , wherein said thermosetting adhesive composition comprises a rubber.  
     
     
         16 . A low loss laminate according to  claim 9 , wherein the first layer or the second layer of the low loss circuit board sheets additionally comprises a ceramic filler.  
     
     
         17 . A low loss laminate according to  claim 9 , additionally comprising a layer selected from a woven fabric substrate impregnated with a thermosetting resin, a nonwoven fabric substrate impregnated with a thermosetting resin, a polymeric film coated with a thermosetting resin, a woven fabric substrate impregnated with a rubber, a nonwoven fabric substrate impregnated with a rubber and a polymeric film coated with a rubber.  
     
     
         18 . A low loss laminate according to  claim 17 , wherein the additional layer is sandwiched between at least two of said low loss circuit board sheets.  
     
     
         19 . A low loss laminate according to  claim 17 , wherein the additional layer comprises a thermoset impregnated fiberglass.