Abstract:
The invention provides a dielectric material with low dielectric loss. The dielectric material comprises (i) 40˜80 parts by weight of polyphenylene ether resin having a Mw of 1000˜7000, a Mn of 1000˜4000 and Mw/Mn=1.0˜1.8; (ii) 5˜30 parts by weight of bismaleimide resins; and (iii) 5˜30 parts by weight of polymer additives, wherein the dielectric material has Dk of 3.75˜4.0 and Df of 0.0025˜0.0045. The dielectric material is suitably used in prepregs and insulation layers of a circuit board, because it has high Tg, low thermal expansion coefficient, low moisture absorption and excellent dielectric properties such as Dk and Df.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a dielectric material with low dielectric loss, particularly to a resin composition. 
     2. Related Art 
     As developed with wireless transmission products and technologies of transmitting high frequency, epoxy resin and novolak resin cannot satisfied for the advance application, especially high frequency printed circuit board (PCB). Fluorine-containing resin can be used as PCB with low dielectric loss. However, fluorine-containing resin is expensive and not easy to work, and thus limited to the use of military and astrodynamics. In addition, polyphenylene ether (PPE) resin has excellent mechanical property and dielectric property such as Dk and Df Therefore, the PPE resin is preferable to be used a material for high frequency PCB. 
     However, because the PPE resin is a thermal plastic resin, as applied in a copper-clad laminate, it may has disadvantages as follows: it is not easy to work due to a high melting viscosity of PPE resin, interlayer film is easy released in a solvent clean step during a process for manufacturing PCB due to a poor solvent resistance of PPE resin, and it is not easy to operate above a temperature of 250° C. in soldering process due to melting point close to Tg. Therefore, PPE resin has to be modified by curing so as to meet the requirement of using in PCB. 
     Curing modification of PPE resin generally has two manners: PPE resin may become curable resin by introducing crosslinking active functional groups to molecular structure of PPE resin. Alternatively, PPE resin may become co-mixing curable composite material by introducing other curable resins to molecular structure of PPE resin with co-mixing modification or interpenetrating network technology. However, PPE resin is likely incompatible with the active functional groups or curable resins, because the polar difference exists in their chemical structures. Alternatively, PPE resin may lose the excellent properties, after it conducts curing modification with the active functional groups or curable resins. 
     Therefore, there is a need to develop a material has excellent dielectric properties and other properties such as high Tg, low coefficient of thermal expansion and low water absorption of PCB requirement. Also, the material can be applied in the manufacture of high frequency PCB. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a dielectric material with low dielectric loss, which has excellent dielectric properties, low coefficient of thermal expansion and low water absorption. 
     To accomplish the above object, there is provided a dielectric material with low dielectric loss, which comprises (i) 40˜80 parts by weight of polyphenylene ether resin having a Mw of 1000˜7000, a Mn of 1000˜4000 and Mw/Mn=1.0˜1.8; (ii) 5˜30 parts by weight of bismaleimide; and (iii) 5˜30 parts by weight of polymer additives, wherein the dielectric material has Dk of 3.75˜4.0 and Df of 0.0025˜0.0045. 
     In the dielectric material with low dielectric loss of the invention, the polyphenylene ether resin is represented by the formula 
     
       
                 
         
             
             
         
      
     
     wherein Y represents at least one C, O and benzene ring or the combination. 
     In the dielectric material with low dielectric loss of the invention, bismaleimide resins are selected from groups consisting of 
     Phenylmethane maleimide 
     
       
                 
         
             
             
         
      
     
     wherein n≧1; 
     Bisphenol A diphenyl ether bismaleimide 
     
       
                 
         
             
             
         
      
     
     3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylethane bismaleimide 
                                
and
 
     1,6-bismaleimide-(2,2,4-trimethyl)hexane. 
     
       
                 
         
             
             
         
      
     
     In the dielectric material with low dielectric loss of the invention, the polymer additives are selected from groups consisting of 
     Homopolymers of Butadiene 
     
       
                 
         
             
             
         
      
     
     wherein y=70% and x+z=30%; 
     Random copolymers of butadiene and styrene 
     
       
                 
         
             
             
         
      
     
     wherein y=30%, x+z=70% and w=≧1, and the amount of styrene=25 wt %; 
     Maleinized Polybutadiene 
     
       
                 
         
             
             
         
      
     
     wherein y=28% and x+z=72%, the amount of maleic anhydride=8 wt %; 
     Butadiene-styrene-divinylbenzene copolymer; and 
     Styrene Maleic Anhydride copolymer 
     
       
                 
         
             
             
         
      
     
     wherein X=1˜8 and n≧1. 
     In the dielectric material with low dielectric loss of the invention, it is preferable that crosslinking agent is added to increase crosslinking density of resins. The crosslinking agents with 40-80 parts by weight may be selected from the following groups consisting of 
     
       
                 
         
             
             
         
      
     
     In the dielectric material with low dielectric loss of the invention, it is preferable that catalyst is added to increase reaction of crosslinking agents and other resins. The catalysts includes at least one peroxide having 116° C.-128° C. for a half life of 10 hours with 2-8 phr based on the total weight of PPE, BMI, polymer additives and crosslinking agents. The suitable peroxides comprise dicumyl peroxide, α,α′-bis(tert-butylperoxy)diisopropyl benzene and 2,5-di(tert-butylperoxy)-2,5-dimethyl-3-hexyne. 
     In the dielectric material with low dielectric loss, it is preferable that filler is added to increase thermal conductivity and mechanical strength, and reduce thermal expansion. The suitable fillers may be fused silica, sphere-shaped silica, talc and aluminum silicate. 
     In order to increase flame retardation of the dielectric material of the invention, halogen-containing flame retardants and flame retardants without halogen may be used. The halogen-containing flame retardants may comprise decabromodiphenyl ethane. The flame retardants without halogen may comprise phosphor-containing flame retardants and phosphates. The phosphor-containing flame retardants and phosphates are produced by ALBEMARLE CO., LTD. The phosphates are like tetrakis(2,6-dimethylphenyl) 1,3-phenytene bisphosphate. tetrakis(2,6-dimethylphenyl) 1,3-phenylene bisphosphate can be represented by the formula,
 
[OC 6 H 3 (CH 3 ) 2 ] 2 P(O)OC 6 H 4 OP(O)[OC 6 H 3 (CH 3 ) 2 ] 2  
 
     The foregoing and other objects, features and advantages of the present invention will be apparent to those skilled in the art from the following detailed description. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     No Drawings 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In one aspect of the present invention, there is provided a thermal curable dielectric material to produce a prepreg in a successive process in the following examples 4-1 to 4-7. The process uses the dielectric material as a coating on a substrate which may be a fiberglass cloth. The apparatus for producing the prepreg includes a pasting tank wherein there are provided a plurality of rolls. The pasting tank is filled with the dielectric material. A roll of fiberglass cloth may enter the pasting tank and pass the plurality of rolls. The fiberglass cloth is sufficiently impregnated with the dielectric material, and then surplus dielectric material is removed by a metering roller. A heat treatment for curing the dielectric material and removing the solvent is required at 100° C. to 350° C. for 1 minute to 5 hours, preferably at 150° C. to 300° C. for 1 minute to 3 hours. The prepreg is Obtained after the cured dielectric material is cooled down and the fiberglass cloth is wrapped. 
     A double-sided copper-clad laminate is produced by providing several prepregs in a neat stack between two electrodeposited copper foils, conducting a hot pressing process under 40 to 900 psi, raising temperature from 80° C. to 200° C. in 30 minutes, and then hot pressing at 200° C. for 120 minutes, and then cooling down to room temperature in 30 minutes in a vacuum pressing machine. The prepreg includes a fiberglass cloth of electrical grade 2116 and the dielectric material. Generally, a double-sided copper-clad laminate with a thickness of 1.0 mm is produced by providing 4 sheets of prepregs in a neat stack between two electrodeposited copper foils, with a thickness of 1.5 mm is produced by providing 7 sheets of prepregs, and with a thickness of 2.0 mm is produced by providing 10 sheets of prepregs. 
     The dielectric material of the present invention may form a stable homogeneous solution in a solvent with a low boiling point. The properties of a copper-clad laminate with the dielectric material of the invention were determined including Tg, heat decomposition temperature, heat decomposition time, solder heat resistance (288° C.), thermal expansion coefficient, water absorption, thermal conductivity, dielectric constant, dielectric loss tangent and flammability according to IPC-TM-650 test method manual. The determining results show the copper-clad laminate with the dielectric material of the invention has high Tg, excellent dielectric properties such as Dk and Df, low water absorption, high thermal resistance and high thermal conductivity. The copper-clad laminate is suitable used as a substrate for electronic elements and IC package. 
     EXAMPLES  
     
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 INFLUENCE OF PPE RESIN AMOUNT 
               
               
                 EXAMPLE 4-1 
               
             
          
           
               
                   
                 AMOUNT OF PPE RESIN 
               
             
          
           
               
                   
                 C1 
                 C2 
                 C3 
                 C4 
                 C5 
                 C6 
                 C7 
               
               
                   
                   
               
             
          
           
               
                 PPE resin 
                 SA9000 
                 60 
                 52.5 
                 45 
                 41 
                 37.5 
                 34 
                 22.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
               
               
                 Polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAIC 
                 15 
                 22.5 
                 30 
                 34 
                 37.5 
                 41 
                 52.5 
               
               
                 agents 
               
               
                 Flame 
                 XP7866, phr 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 retardants 
               
               
                 fillers 
                 Fused silica, 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                   
                 phr 
               
               
                 catalysts 
                 Peroxide 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 119° C. for a 
               
               
                   
                 half life of 
               
               
                   
                 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 206 
                 224 
                 229 
                 221 
                 212 
                 213 
                 212 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient of 
                 IPC-TM-650 
                 58/334 
                 60/305 
                 56/251 
                 53/247 
                 56/211 
                 61/204 
                 55/245 
               
               
                 thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), ppm/° C. 
               
               
                 water 
                 PCT/121° C./ 
                 0.29 
                 0.33 
                 0.34 
                 0.34 
                 0.39 
                 0.39 
                 0.40 
               
               
                 absorption 
                 1 hr 
               
               
                 288° C. 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 thermal 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.93 
                 3.89 
                 3.89 
                 3.89 
                 3.90 
                 3.86 
                 3.87 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0057 
                 0.0054 
                 0.0048 
                 0.0044 
                 0.0040 
                 0.0040 
                 0.0039 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
         
       
     
     Tg, Dk and Df were compared with different ratio and amount of PPE. The Tg level may be affected by the amount of PPE used. Also, the amount of PPE may also have an effect on the Dk and Df value. When the amount of PPE is high, Dk and Df may be high. When the amount of PPE is low, Dk and Df may be low. Typically, a low value for the Dk and Df is preferred. In addition, the thermal expansion coefficient may be raised when PPE is added, and BMI is added to balance the effect. In Table 1, part number SA9000 of PPE with chemical name of Polyphenylene Oxide (PPO) or Polyphenylene Ether (PPE) is produced by Sabic CO., LTD. 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 INFLUENCE OF BMI RESIN SPECIES AND AMOUNT 
               
               
                 EXAMPLE 4-2 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 BMI RESIN 
               
             
          
           
               
                   
                   
                 A1 
                 A2 
                 A3 
                 A4 
                 A5 
                 A6 
                 A7 
                 A8 
               
               
                   
               
               
                 PPE resin 
                 SA9000 
                 42.5 
                 40 
                 37.5 
                 35 
                 32.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 2300 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 15 
                 0 
               
               
                   
                 4000 
                 0 
                 0 
                 0 
                 0 
                 0 
                 15 
                 0 
                 0 
               
               
                   
                 5100 
                 5 
                 10 
                 15 
                 20 
                 25 
                 0 
                 0 
                 0 
               
               
                   
                 TMH 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 15 
               
               
                 Polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAIC 
                 42.5 
                 40 
                 37.5 
                 35 
                 32.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 agents 
               
               
                 Flame 
                 XP7866, 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 retardants 
                 phr 
               
               
                 fillers 
                 Fused 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                   
                 silica, 
               
               
                   
                 phr 
               
               
                 catalysts 
                 Peroxide 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 119° C. 
               
               
                   
                 for a half 
               
               
                   
                 life of 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 210 
                 212 
                 212 
                 211 
                 211 
                 212 
                 222 
                 195 
               
               
                   
                 2.4.24.3 
               
               
                 Coefficient of 
                 IPC-TM-650 
                 60/296 
                 58/250 
                 56/211 
                 54/207 
                 50/197 
                 55/260 
                 45/170 
                 45/288 
               
               
                 thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), 
               
               
                 ppm/° C. 
               
               
                 water 
                 PCT/121° C./ 
                 0.30 
                 0.34 
                 0.39 
                 0.44 
                 0.46 
                 0.41 
                 0.47 
                 0.33 
               
               
                 absorption 
                 1 hr 
               
               
                 288° C. 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 thermal 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.85 
                 3.87 
                 3.90 
                 3.94 
                 3.98 
                 3.91 
                 3.93 
                 3.86 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0040 
                 0.0041 
                 0.0040 
                 0.0042 
                 0.0043 
                 0.0042 
                 0.0046 
                 0.0041 
               
               
                 flam- 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-1 
                 V-0 
                 V-0 
               
               
                 mability 
               
               
                   
               
             
          
           
               
                   
                 BMI RESIN 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Compar-ative 
               
               
                   
                   
                 A9 
                 A10 
                 A11 
                 A12 
                 A13 
                 A14 
                 A15 
                 example 
               
               
                   
               
               
                 PPE resin 
                 SA9000 
                 37 
                 37 
                 37 
                 37 
                 37 
                 37.5 
                 37 
                 50 
               
               
                 BMI resin 
                 2300 
                 8 
                 0 
                 8 
                 0 
                 0 
                 5 
                 4 
                 0 
               
               
                   
                 4000 
                 8 
                 8 
                 0 
                 8 
                 0 
                 5 
                 4 
                 0 
               
               
                   
                 5100 
                 0 
                 8 
                 0 
                 0 
                 8 
                 5 
                 4 
                 0 
               
               
                   
                 TMH 
                 0 
                 0 
                 8 
                 8 
                 8 
                 0 
                 4 
                 0 
               
               
                 Polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
                 0 
               
               
                 Crosslinking 
                 TAIC 
                 37 
                 37 
                 37 
                 37 
                 37 
                 37.5 
                 37 
                 50 
               
               
                 agents 
               
               
                 Flame 
                 XP7866, 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 retardants 
                 phr 
               
               
                 fillers 
                 Fused 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                   
                 silica, 
               
               
                   
                 phr 
               
               
                 catalysts 
                 Peroxide 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 119° C. 
               
               
                   
                 for a half 
               
               
                   
                 life of 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 208 
                 204 
                 205 
                 200 
                 214 
                 210 
                 207 
                 218 
               
               
                   
                 2.4.24.3 
               
               
                 Coefficient of 
                 IPC-TM-650 
                 50/210 
                 57/278 
                 45/230 
                 52/268 
                 54/290 
                 53/240 
                 49/225 
                 64/325 
               
               
                 thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), 
               
               
                 ppm/° C. 
               
               
                 water 
                 PCT/121° C./ 
                 0.43 
                 0.42 
                 0.41 
                 0.36 
                 0.44 
                 0.40 
                 0.39 
                 0.33 
               
               
                 absorption 
                 1 hr 
               
               
                 288° C. 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 thermal 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.96 
                 3.91 
                 3.90 
                 3.87 
                 3.89 
                 3.91 
                 3.90 
                 3.80 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0041 
                 0.0041 
                 0.0045 
                 0.004 
                 0.0039 
                 0.0041 
                 0.0043 
                 0.0044 
               
               
                 flam- 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                 mability 
               
               
                   
               
             
          
         
       
     
     The coefficient of thermal expansion was measured with different species and amount of BMI resin. The more the amount of BMI resin is, the lower the coefficient of thermal expansion is. In the example, there are three kinds of comparison comprising three groups that A1-A5 shows different amount of BMI with the same species, A6-A8 shows the same amount of BMI with different species and A9-A15 shows about the same total amount of BMI with more than two species. In Table 2, part numbers 2300, 4000, 5100 and TMH of BMI are produced by Daiwakasei Industry CO., LTD, in which part number 2300 has chemical name of phenyl methane maleimide, part number 4000 has chemical name of 2,2′-bis[4-(4-maleimidophenoxy)phenyl]propane, part number 5100 has chemical name of 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide and part number TMH has chemical name of 1,6′-bismaleimide-(2,2,4-trimethyl)hexane. 
     It can be found from group A1-A5 that by increasing the amount of BMI resin, the thermal expansion coefficient would decrease. However, by increasing the amount of BMI resin, the water absorption would also increase. As to group A6-A8, different BMI resins may reduce the thermal expansion coefficient, but would also affect the water absorption. Regarding group A9-A15, different combination of BMI resins may reduce the thermal expansion coefficient, and affect the water absorption also. In the invention, the object of addition of BMI to the dielectric material is to reduce the thermal expansion coefficient. However, the more the amount of BMI resin is, the higher the water absorption is. Therefore, the polymer additives are added to reduce the water absorption. 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 INFLUENCE OF POLYMER ADDITIVES SPECIES AND AMOUNT 
               
               
                 EXAMPLE 4-3 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 POLYMER ADDITIVES 
               
             
          
           
               
                   
                   
                 B1 
                 B2 
                 B3 
                 B4 
                 B5 
                 B6 
                 B7 
               
               
                   
               
               
                 PPE resin 
                 SA9000 
                 40 
                 37.5 
                 35 
                 32.5 
                 30 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
               
               
                 Polybutadiene 
                 Ricon100 
                 5 
                 10 
                 15 
                 20 
                 25 
                 0 
                 0 
               
               
                   
                 Ricon130MA8 
                 0 
                 0 
                 0 
                 0 
                 0 
                 10 
                 0 
               
               
                   
                 Ricon150 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 10 
               
               
                   
                 Ricon257 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 SMA 
                 S:M = 3:1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 4:1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 5:1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 6:1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 8:1 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 Crosslinking 
                 TAIC 
                 40 
                 37.5 
                 35 
                 32.5 
                 30 
                 37.5 
                 37.5 
               
               
                 agents 
               
               
                 Flame retardant 
                 XP7866, phr 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 Fillers 
                 Fused silica, phr 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 catalysts 
                 Peroxide 119° C. 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 for a half life of 
               
               
                   
                 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 221 
                 212 
                 200 
                 194 
                 186 
                 213 
                 217 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient of 
                 IPC-TM-650 
                 53/201 
                 56/211 
                 64/220 
                 67/260 
                 74/300 
                 58/265 
                 57/270 
               
               
                 thermal expansion 
                 2.4.24 
               
               
                 (α1/α2), ppm/° C. 
               
               
                 water absorption 
                 PCT/121° C./1 hr 
                 0.43 
                 0.39 
                 0.35 
                 0.32 
                 0.28 
                 0.45 
                 0.43 
               
               
                 288° C. thermal 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.93 
                 3.90 
                 3.87 
                 3.86 
                 3.84 
                 3.92 
                 3.90 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0043 
                 0.0040 
                 0.0041 
                 0.0040 
                 0.0039 
                 0.0045 
                 0.0044 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-1 
                 V-1 
                 V-0 
                 V-0 
               
               
                   
               
             
          
           
               
                   
                 POLYMER ADDITIVES 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                   
                 Comparative 
               
               
                   
                   
                 B9 
                 B10 
                 B11 
                 B12 
                 B13 
                 example 
               
               
                   
               
               
                 PPE resin 
                 SA9000 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 42.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
               
               
                 Polybutadiene 
                 Ricon100 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Ricon130MA8 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Ricon150 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 Ricon257 
                 0 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                 SMA 
                 S:M = 3:1 
                 10 
                 0 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 4:1 
                 0 
                 10 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 5:1 
                 0 
                 0 
                 10 
                 0 
                 0 
                 0 
               
               
                   
                 S:M = 6:1 
                 0 
                 0 
                 0 
                 10 
                 0 
                 0 
               
               
                   
                 S:M = 8:1 
                 0 
                 0 
                 0 
                 0 
                 10 
                 0 
               
               
                 Crosslinking 
                 TAIC 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 42.5 
               
               
                 agents 
               
               
                 Flame retardants 
                 XP7866, phr 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 fillers 
                 Fused silica, phr 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 catalysts 
                 Peroxide 119° C. 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 for a half life of 
               
               
                   
                 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 220 
                 215 
                 210 
                 206 
                 195 
                 222 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient of 
                 IPC-TM-650 
                 45/232 
                 48/237 
                 50/245 
                 51/240 
                 53/260 
                 45/200 
               
               
                 thermal expansion 
                 2.4.24 
               
               
                 (α1/α2), ppm/° C. 
               
               
                 water absorption 
                 PCT/121° C./1 hr 
                 0.46 
                 0.45 
                 0.43 
                 0.43 
                 0.40 
                 0.56 
               
               
                 288° C. thermal 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.95 
                 3.95 
                 3.93 
                 3.91 
                 3.90 
                 3.93 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0085 
                 0.0073 
                 0.0064 
                 0.0056 
                 0.0042 
                 0.0043 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
         
       
     
     The water absorption was measured with different species and amount of polymer additives. Polybutadiene (PB) and styrene-maleic anhydride (SMA) were used as the polymer additives in the invention. It can be found from using the different amount of PB with the same species that by increasing the amount of PB, the water absorption would decrease. However, with the increasing amount of PB, the coefficient of thermal expansion would also increase. As to using different species of PB in combination with SMA, it shows SMA can reduce the water absorption and the coefficient of thermal expansion, but Df may remain high. However, PB can be used to reduce Df. In Table 3, part numbers Ricon100, Ricon130MA8, Ricon150 and Ricon257 of PB are produced by Sartomer CO., LTD, in which part number Ricon 100 has chemical name of butadiene styrene copolymer, part number Ricon130MA8 has chemical name of butadiene adducted with maleic anhydride, part number Ricon 150 has chemical name of polybutadiene resin and Ricon 257 has chemical name of polybutadiene grafted with styrene and benzene in toluene solution. In Table 3, SMA with S:M=3:1 indicates that the ratio of styrene to maleic anhydride is 3 to 1. Generally, the ratios are about 1:1˜12:1. 
     
       
         
               
             
               
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 INFLUENCE OF DIFFERENT SPECIES 
               
               
                 OF CROSSLINKING AGENTS 
               
             
          
           
               
                   
                 CROSSLINKING AGENT 
               
             
          
           
               
                 EXAMPLE 4-4 
                 D1 
                 D2 
                 D3 
               
               
                   
               
             
          
           
               
                 PPE resin 
                 SA9000 
                 37.5 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
               
               
                 polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAC 
                 37.5 
                 0 
                 0 
               
               
                 agents 
                 TAIC 
                 0 
                 37.5 
                 0 
               
               
                   
                 TBS 
                 0 
                 0 
                 37.5 
               
               
                 Flame 
                 XP7866, phr 
                 20 
                 20 
                 20 
               
               
                 retardants 
               
               
                 fillers 
                 Fused silica, phr 
                 20 
                 20 
                 20 
               
               
                 catalysts 
                 Peroxide 119° C. 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 for a half life 
               
               
                   
                 of 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 183 
                 212 
                 202 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient 
                 IPC-TM-650 
                 59/273 
                 56/211 
                 50/250 
               
               
                 of thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), 
               
               
                 ppm/° C. 
               
               
                 water 
                 PCT/121° C./1 hr 
                 0.39 
                 0.39 
                 0.12 
               
               
                 absorption 
               
               
                 288° C. 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 thermal 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.95 
                 3.90 
                 3.75 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0039 
                 6.0040 
                 0.0035 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
         
       
     
     The dielectric material of the invention may comprise at least one crosslinking agent with 40-80 parts by weight selected from the following groups consisting of Triallyl cyanurate (TAC), Triallyl isocyanurate (TAIC) and 4-tert-butylstyrene. The properties of a copper-clad laminate with the dielectric material of the invention were measured with different species of crosslinking agents. It can be found by using TAC that Tg and the coefficient of thermal expansion were poor, and water absorption, Dk and Df were of ordinary level. As to TAIC, all the properties of a copper-clad laminate with the dielectric material of the invention were of ordinary level. Regarding 4-tert-butylstyrene, the coefficient of thermal expansion, water absorption and Df were excellent, but Dk is low, 
     
       
         
               
             
               
               
             
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 INFLUENCE OF DIFFERENT SPECIES OF FLAME RETARDANTS 
               
             
          
           
               
                   
                 FLAME RETARDANTS 
               
             
          
           
               
                 EXAMPLE 4-5 
                 E1 
                 E2 
                 E3 
                 E4 
               
               
                   
               
             
          
           
               
                 PPE resin 
                 SA9000 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
               
               
                 polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAIC 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 agents 
               
               
                 Flame 
                 Decabromodiphenyl 
                 10 
                 0 
                 0 
                 0 
               
               
                 retardants 
                 Ethane, pbr 
               
               
                   
                 XP7866, phr 
                 0 
                 20 
                 15 
                 10 
               
               
                   
                 Tetrakis(2,6-di- 
                 0 
                 0 
                 5 
                 10 
               
               
                   
                 methylphenyl) 
               
               
                   
                 1,3-phenylene 
               
               
                   
                 bisphosphate, phr 
               
               
                 fillers 
                 Fused silica, phr 
                 20 
                 20 
                 20 
                 20 
               
               
                 catalysts 
                 Peroxide 119° C. 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 for a half life 
               
               
                   
                 of 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 224 
                 212 
                 226 
                 180 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient 
                 IPC-TM-650 
                 55/233 
                 56/211 
                 65/267 
                 67/339 
               
               
                 of thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), 
               
               
                 ppm/° C. 
               
               
                 water 
                 PCT/121° C./1 hr 
                 0.43 
                 0.39 
                 0.37 
                 0.30 
               
               
                 absorption 
               
               
                 288° C. 
                 Dip288° C. 
                 &gt;60 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 thermal 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.83 
                 3.90 
                 3.87 
                 3.85 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0043 
                 0.0040 
                 0.0040 
                 0.0037 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
         
       
     
     If desired, the dielectric material of the invention may optionally comprise flame retardants. A halogen-containing flame retardant of decabromodiphenyl ethane with 7-15 phr based on the total weight of PPE, BMI, polymer additives and crosslinking agents may be added to the dielectric material of the invention. The dielectric material of the invention may comprise at least one flame retardant without halogen with 12-14 phr based on the total weight of PPE, BMI, polymer additives and crosslinking agents selected from the following groups consisting of phosphor-containing flame retardants and phosphates. The phosphor-containing flame retardants and phosphates are produced by ALBEMARLE CO., LTD. The phosphates are like tetrakis(2,6-dimethylphenyl) 1,3-phenylene bisphosphate. 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 INFLUENCE OF DIFFERENT SPECIES OF FILLERS 
               
               
                 EXAMPLES 4-6 
               
             
          
           
               
                   
                 FILLERS 
               
             
          
           
               
                   
                 F1 
                 F2 
                 F3 
                 F4 
                 F5 
                 F6 
                 F7 
               
               
                   
                   
               
             
          
           
               
                 PPE resin 
                 SA9000 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
               
               
                 polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAIC 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 agents 
               
               
                 Flame 
                 XP7866, phr 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                 retardants 
               
               
                 fillers 
                 Fused silica, 
                 0 
                 20 
                 10 
                 10 
                 30 
                 25 
                 45 
               
               
                   
                 phr 
               
               
                   
                 Ball type 
                 20 
                 0 
                 10 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 silica 
               
               
                 catalysts 
                 Peroxide 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                   
                 119° C. for a 
               
               
                   
                 half life of 
               
               
                   
                 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 210 
                 212 
                 214 
                 220 
                 208 
                 215 
                 195 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient of 
                 IPC-TM-650 
                 53/220 
                 56/211 
                 52/225 
                 58/260 
                 45/210 
                 50/220 
                 40/205 
               
               
                 thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), ppm/° C. 
               
               
                 water 
                 PCT/121° C./1 hr 
                 0.41 
                 0.39 
                 0.40 
                 0.39 
                 0.38 
                 0.40 
                 0.36 
               
               
                 absorption 
               
               
                 288° C. thermal 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.87 
                 3.90 
                 3.88 
                 3.85 
                 3.96 
                 4.01 
                 4.06 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0039 
                 0.0040 
                 0.0040 
                 0.0040 
                 0.0041 
                 0.0043 
                 0.0045 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
         
       
     
     The dielectric material of the invention may optionally comprise fillers. The suitable fillers such as fused silica and sphere-shaped silica may be used. The suitable amount of filler is 8-50 phr based on the total weight of PPE, BMI, polymer additives and crosslinking agents. It can be found from the fused silica and the sphere-shaped silica with the same amount that the sphere-shaped silica has lower Dk and Df than the fused silica. 
     
       
         
               
             
               
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
               
                   
               
               
                 INFLUENCE OF DIFFERENT AMOUNT AND SPECIES OF CATALYSTS 
               
               
                 EXAMPLE 4-7 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 CATALYSTS 
               
             
          
           
               
                   
                   
                 G1 
                 G2 
                 G3 
                 G4 
               
               
                   
               
               
                 PPE resin 
                 SA9000 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
               
               
                 polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAIC 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 agents 
               
               
                 Flame 
                 XP7866, phr 
                 20 
                 20 
                 20 
                 20 
               
               
                 retardants 
               
               
                 fillers 
                 Ball type silica 
                 20 
                 20 
                 20 
                 20 
               
               
                 catalysts 
                 Peroxide 116° C. for a 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 half life of 10 hrs 
               
               
                   
                 Peroxide 119° C. for a 
                 2.5 
                 3 
                 7 
                 8 
               
               
                   
                 half life of 10 hrs 
               
               
                   
                 Peroxide 128° C. for a 
                 0 
                 0 
                 0 
                 0 
               
               
                   
                 half life of 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 212 
                 220 
                 222 
                 227 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient of 
                 IPC-TM-650 
                 56/211 
                 53/225 
                 49/220 
                 50/180 
               
               
                 thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), 
               
               
                 ppm/° C. 
               
               
                 water 
                 PCT/121° C./1 hr 
                 0.39 
                 0.43 
                 0.47 
                 0.60 
               
               
                 absorption 
               
               
                 288° C. thermal 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.90 
                 3.91 
                 3.90 
                 3.96 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0040 
                 0.0042 
                 0.0045 
                 0.0049 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
           
               
                   
                 CATALYSTS 
               
             
          
           
               
                   
                   
                 G5 
                 G6 
                 G7 
                 G8 
                 G9 
               
               
                   
               
               
                 PPE resin 
                 SA9000 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 BMI resin 
                 5100 
                 15 
                 15 
                 15 
                 15 
                 15 
               
               
                 polybutadiene 
                 Ricon100 
                 10 
                 10 
                 10 
                 10 
                 10 
               
               
                 Crosslinking 
                 TAIC 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
                 37.5 
               
               
                 agents 
               
               
                 Flame 
                 XP7866, phr 
                 20 
                 13 
                 13 
                 13 
                 13 
               
               
                 retardants 
               
               
                 fillers 
                 Ball type silica 
                 20 
                 13 
                 13 
                 13 
                 13 
               
               
                 catalysts 
                 Peroxide 116° C. for a 
                 2.5 
                 0 
                 1.5 
                 1.5 
                 1 
               
               
                   
                 half life of 10 hrs 
               
               
                   
                 Peroxide 119° C. for a 
                 0 
                 0 
                 0 
                 1.5 
                 1 
               
               
                   
                 half life of 10 hrs 
               
               
                   
                 Peroxide 128° C. for a 
                 0 
                 2.5 
                 1.5 
                 0 
                 1 
               
               
                   
                 half life of 10 hrs 
               
               
                 Tg, TMA 
                 IPC-TM-650 
                 208 
                 225 
                 220 
                 209 
                 215 
               
               
                   
                 2.4.24.3 
               
               
                 coefficient of 
                 IPC-TM-650 
                 57/230 
                 50/230 
                 47/226 
                 52/220 
                 50/235 
               
               
                 thermal 
                 2.4.24 
               
               
                 expansion 
               
               
                 (α1/α2), 
               
               
                 ppm/° C. 
               
               
                 water 
                 PCT/121° C./1 hr 
                 0.42 
                 0.38 
                 0.40 
                 0.42 
                 0.38 
               
               
                 absorption 
               
               
                 288° C. thermal 
                 Dip288° C. 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
                 &gt;600 
               
               
                 resistance 
               
               
                 Dk(2-10 GHz) 
                 Cavity 
                 3.88 
                 3.91 
                 3.92 
                 3.93 
                 3.91 
               
               
                 Df(2-10 GHz) 
                 Cavity 
                 0.0039 
                 0.0040 
                 0.0041 
                 0.0042 
                 0.0039 
               
               
                 flammability 
                 UL94 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
                 V-0 
               
               
                   
               
             
          
         
       
     
     The dielectric material of the invention may optionally comprise catalysts including peroxides having 116° C.-128° C. for a half life of 10 hours. The suitable amount of peroxide is 2-8 phr based on the total weight of PPE, BMI, polymer additives and crosslinking agents. The preferable catalyst is a peroxide having 119° C. for a half life of 10 hours. 
     The dielectric material of the invention may comprise PPE, but not comprise epoxy resin. The desired values of Dk and/or Df cannot be obtained, if epoxy resin is added to the dielectric material of the invention. When reacting epoxy resin with the dielectric material of the invention, the open rings of the epoxy resin may produce excess OH groups, therefore causing the Dk and Df value to remain high and unable to decrease.