Microwave-transparent thermosetting resin compositions, electrical laminates obtained therefrom, and process of producing these

Abstract

The present invention relates to a thermosetting resin composition with excellent electrical properties comprising (a) one or more terminally unsaturated urethane resins, (b) styrene, and (c) brominated styrene. The aforementioned composition finds great utility as a printed circuit board laminate suitable for use at microwave frequencies.

What is claimed is:  
     
         1 . A thermosetting resin composition, comprising: 
 (a) One or more terminally unsaturated urethanes selected from the group of: 
   1 ) one characterized by the formula:  
                     
  where R 1  is H or CH 3 , R 2  is an organic residue from a monohydric alcohol and R 3  is an organic residue from a diisocyanate;  
   2 ) and one characterized by the formula:  
                     
  where R 1  is H or CH 3 , R 2  is an organic residue from a monohydric alcohol and R 3  is an organic residue from a diisocyanate, and R 4  is an isocyanurate compound of the following structure:  
                     
    and    (b) Styrene monomer; and    (c) Bromostyrene, characterized by the formula:                          wherein, the ratio of the sum of components (a) to the sum of components (b) and (c) is less than 0.2, and the ratio of (b) to (c) is less than 1.5.    
     
     
         2 . The composition according to  claim 1  further comprising a catalyst in about 0.1% to about 2% by weight of the total composition.  
     
     
         3 . The composition according to  claim 2  wherein the catalyst is selected from the group consisting of the t-butyl peroctoate, t-butyl peroxy benzoate, dicumyl peroxide, benzoyl peroxide, cumene hydrogen peroxide, t-butyl perbenzoate, t-butyl peroxide and combinations thereof.  
     
     
         4 . The composition according to  claim 3  wherein the catalyst comprises t-butyl peroctoate in about 0.2% by weight of the total composition.  
     
     
         5 . The composition according to  claim 3  wherein the catalyst comprises t-butyl peroxy benzoate in about 0.25% by weight of the total composition.  
     
     
         6 . The composition according to  claim 3  wherein the catalyst comprises dicumyl peroxide in about 0.25% by weight of the total composition.  
     
     
         7 . The composition according to  claim 1  wherein said styrene monomer is selected from the group consisting of styrene, halogenated styrene, and an alpha alkyl styrene.  
     
     
         8 . The composition of  claim 7  wherein said styrene monomer is an alpha alkyl styrene.  
     
     
         9 . The composition of  claim 7  wherein said styrene monomer is a halogenated styrene.  
     
     
         10 . The composition of  claim 9  wherein said halogenated styrene monomer is selected from the group consisting of dibromostyrene, tribromostyrene and pentabromobenzyl acrylate.  
     
     
         11 . The composition of  claim 1  further comprising divinyl benzene in about 0.1% to about 10% by weight of the total composition.  
     
     
         12 . The composition of  claim 11  wherein the divinyl benzene is from about 0.5% to about 5% by weight of the total composition.  
     
     
         13 . The composition of  claim 12  wherein the divinyl benzene is from about 1% to about 4% by weight of the total composition.  
     
     
         14 . The composition of  claim 1  further comprising additives selected from the group consisting of moisture scavengers, molecular sieves, organic fillers, inorganic fillers, oxides, polyethylene fillers, rheology modification fillers, surface active agents, monomers which modify viscosity and performance, colorants, fluorescent dyes, U.V. blockers, wetting agents, air release agents, defoamers, adhesion promoters, flame retardant synergists, styrene, vinyl toluene, t-butyl-styrene, paramethyl styrene, diallyl phthalate, 2,4,ethyl-methylimidazole, 3-ethyl-2-methyl-2-(3-methylbutyl)-1,3-oxazolidine and combinations thereof.  
     
     
         15 . The composition of  claim 14  wherein the oxide comprises titanium dioxide.  
     
     
         16 . The composition of  claim 14  wherein the oxide comprises expanded polyethylene compounds.  
     
     
         17 . The composition of  claim 14  wherein the filler which modifies rheology is calcined kaolin.  
     
     
         18 . The composition of  claim 14  wherein the monomer which modifies viscosity and performance comprises methyl methacrylate.  
     
     
         19 . A method of producing an electrical laminate comprising the steps of: 
 (1) impregnating at least one substrate with a thermosetting resin composition comprising catalysts which induce free radical cure, polymerization, or UV initiation, in about 0.1% to about 2% by weight of the total composition; and    (2) curing the resin impregnated substrate to produce an electrical laminate.    
     
     
         20 . The method of  claim 19  wherein the curing mechanism is selected from the group consisting of heating without pressure, heating with pressure, electron beam processing, and ultra-violet light processing in conjunction with U.V. initiators.  
     
     
         21 . The method of  claim 19  wherein the substrates are materials selected from the group consisting of organic or inorganic fillers, woven fiberglass, glass paper, glass cloth, glass mat, polyimide paper, woven polymeric fibers and non-woven polymer fiber reinforcements.  
     
     
         22 . The method of  claim 19  further comprising cladding an electrically conductive layer on at least one side of the impregnated substrate before curing.  
     
     
         23 . The method of  claim 19  further comprising cladding an electrically conductive layer on at least one side of the impregnated substrate after curing.  
     
     
         24 . The method of  claim 22  wherein the electrically conductive layer is a metal selected from the group of aluminum, silver, gold, brass and copper.  
     
     
         25 . The method of  claim 23  wherein the electrically conductive layer is a metal selected from the group consisting of aluminum, silver, gold, brass and copper.  
     
     
         26 . The method of  claim 19  wherein the impregnating step involves more than one substrate and the method further comprises laminating the substrates before the curing step.  
     
     
         27 . The method of  claim 26  wherein the curing mechanism is selected from the group consisting of heating without pressure, heating with pressure, electron beam processing, and ultra-violet light processing in conjunction with U.V. initiators.  
     
     
         28 . The method of  claim 26  wherein the substrates are materials selected from the group consisting of organic or inorganic fillers, woven fiberglass, glass paper, glass cloth, glass mat, polyimide paper, woven polymeric fibers and non-woven polymer fiber reinforcements.  
     
     
         29 . The method of  claim 26  further comprising cladding an electrically conductive layer on at least one side of the impregnated substrate before curing.  
     
     
         30 . The method of  claim 19  further comprising cladding an electrically conductive layer on at least one side of the impregnated substrate after curing.  
     
     
         31 . The method of  claim 29  wherein the electrically conductive layer is a metal selected from the group of aluminum, silver, gold, brass and copper.  
     
     
         32 . The method of  claim 30  wherein the electrically conductive layer is a metal selected from the group consisting of aluminum, silver, gold, brass and copper.  
     
     
         33 . An electrical laminate obtained by 
 (1) impregnating at least one substrate with a thermosetting resin composition comprising: 
 (a) One or more terminally unsaturated urethanes selected from the group of: 
 1) one characterized by the formula:  
                     
  where R 1  is H or CH 3 , R 2  is an organic residue from a monohydric alcohol and R 3  is an organic residue from a diisocyanate;  
 2) and one characterized by the formula:  
                     
  where R 1  is H or CH 3 , R 2  is an organic residue from a monohydric alcohol and R 3  is an organic residue from a diisocyanate, and R 4  is an isocyanurate compound of the following structure:  
                     
 
  and  
 (b) Styrene monomer; and  
 (c) Bromostyrene, characterized by the formula:  
                     
    wherein, the ratio of the sum of components (a) to the sum of components (b) and (c) is less than 0.2, and the ratio of (b) to (c) is less than 1.5; and 
 (d) catalysts which induce free radical cure, polymerization, or UV initiation, in about 0.1% to about 2% by weight of the total composition; and  
   (2) curing the resin impregnated substrate to produce an electrical laminate.    
     
     
         34 . The laminate of  claim 33  wherein the composition resin further comprises a halogenated vinyl functional monomer.  
     
     
         35 . The laminate of  claim 34  wherein the composition further comprises glacial methacrylic acid.  
     
     
         36 . The laminate of  claim 35  wherein the composition further comprises divinyl benzene.  
     
     
         37 . The laminate of  claim 36  wherein the composition further comprises additional components selected from the group consisting of moisture scavengers, molecular sieves, organic fillers, inorganic fillers, monomers to increase or decrease the dielectric constant, monomer to reduce the dissipation factor, polyethylene fillers, monomers to modify rheology, surface active agents, monomers to modify viscosity and performance, colorants, fluorescent dye, U.V. blockers, wetting agents, air release agents, defoaming agents, flame retardant synergists, adhesion promoters, epoxies, styrene, vinyl toluene, t-butyl styrene, paramethyl styrene, diallyl phthalate, and 2,4,ethyl-methyl imidazole, 3-ethyl-2-methyl-2-3(3-methylbutyl)-1,3-oxazolidine, methyl methacrylate and combinations thereof.  
     
     
         38 . The laminate of  claim 37  wherein the substrates are materials selected from the group consisting of organic or inorganic fillers, woven fiberglass, glass paper, glass cloth, glass mat, polyimide paper, woven polymeric fibers and non-woven polymer fiber reinforcements.  
     
     
         39 . The laminate of  claim 38  further comprising an electrically conductive layer clad on at least one side of the cured impregnated substrate.  
     
     
         40 . The laminate of  claim 39  wherein the electrically conductive layer is a metal selected from the group of aluminum, silver, gold, brass and copper.  
     
     
         41 . The laminate of  claim 38  wherein more than one substrate is impregnated with the thermosetting resin and are laminated together before the curing step.  
     
     
         42  The laminate of  claim 41  having an electrical conductive layer clad on at least one side of the laminated cured substrates.  
     
     
         43 . The laminate of  claim 42  wherein the electrical conductive layer is a metal selected from the group of aluminum, silver, gold, brass and copper.  
     
     
         44 . An electrical laminate, comprising at least one reinforcement substrate and a crossed linked, thin wall thermosetting resin composition comprising: 
 (a) One or more terminally unsaturated urethanes selected from the group of: 
 1) one characterized by the formula:  
                     
  where R 1  is H or CH 3 , R 2  is an organic residue from a monohydric alcohol and R 3  is an organic residue from a diisocyanate;  
 2) and one characterized by the formula:  
                     
  where R 1  is H or CH 3 , R 2  is an organic residue from a monohydric alcohol and R 3  is an organic residue from a diisocyanate, and R 4  is an isocyanurate compound of the following structure:  
                     
    and    (b) Styrene monomer; and    (c) Bromostyrene, characterized by the formula:                          wherein, the ratio of the sum of the components (a) to the sum of components (b) and (c) is less than 0.2, and the ratio of (b) to (c) is less than 1.5; and    (d) catalysts which induce free radical cure, polymerization, or UV initiation, in about 0.1% to about 2% by weight of the total composition.    
     
     
         45 . The laminate of  claim 44  further comprising an electrically conductive cladding on at least one side.  
     
     
         46 . A multilayer electrical laminate comprising a combination of single sided and double sided laminates according to the laminate of  claim 45 .  
     
     
         47 . The laminate of  claim 44  wherein the thickness range is from about 0.003 to about 0.120 inches thick.