it has now been found that when a polysulfone is added to a poly ( ether sulfone ), a circuit board substrate molded from the resultant composition has improved plateability . the combination of polysulfone and poly ( ether sulfone ) yields adequate heat distortion temperatures and susceptibility to chromic acid etching such that the combination performs better than the individual components in molding circuit board substrates . the composition used for making circuit board substrates and electrical connectors comprises from about 40 to about 90 , preferably from about 50 to about 85 , weight percent of a poly ( ether sulfone ) and from about 10 to about 60 , preferably from abut 15 to about 50 , weight percent of polysulfone . the poly ( ether sulfone ) suitable for use in this invention include homopolymers , co - and higher polymers having repeating units of the following formula : ## str1 ## wherein r is selected from o and s , each r 1 is independently hydrogen , a halogen atom , an alkyl groups of from 1 to 4 carbon atoms and an alkoxy group of from 1 to 4 carbon atoms and a is an integer of 0 to 4 . perferably , the poly ( ether sulfone ) has repeating units of the following formula : ## str2 ## these polymers are well known in the art and are described in , for example , u . s . pat . nos . 4 , 175 , 175 and 4 , 008 , 203 . a preferred copolymer contains units of the following formulae : ## str3 ## wherein r 1 and a are defined as above , and b is independently an integer of 1 to 3 . the ratio of unit ( i ) to unit ( ii ) is preferably greater than 1 . units ( i ) and ( ii ) are attached to each other by an -- o -- bond . the polysulfone suitable for use in this invention includes homopolymers and co - and higher polymers having repeating units of the following formula : ## str5 ## wherein r 1 and a are defined as above and r 2 is a bond between aromatic carbon atoms or a divalent connecting radical . preferably , r 2 is a divalent connecting radical of the formula : ## str6 ## wherein r 3 is independently selected from lower alkyl , aryl and halogen substituted groups thereof . preferably r 3 is methyl . these polymers are well known in the art and are described in , for example , u . s . pat . no . 4 , 175 , 175 . the composition may contain other ingredients such as stabilizers , i . e ., metal oxides such as zinc oxide , antioxidants , flame retardants , pigments , fibers , inorganic fillers , and the like . preferably , the composition contains fibers and / or inorganic fillers . the reinforcing fiber includes fiberglass , carbon fibers , and the like , and mixtures thereof . the particulate inorganic fillers which may be used include wollastonite , calcium carbonate , glass beads , talc , mica and the like , or mixtures thereof . the fiber reinforcement , filler or combinations thereof , is utilized in amounts of from 0 to about 50 weight percent , preferably from about 10 to about 35 weight percent . the compositions of this invention are prepared by any conventional mixing methods . for example , a preferred method comprises mixing the poly ( ether sulfone ), polysulfone and other optional ingredients in powder or granular form in an extruder and extruding the mixture into strands , chopping the strands into pellets and molding the pellets into the desired circuit board substrate and electrical connector . the composition of this invention can be molded into circuit board substrates and electrical connectors using conventional techniques . specifically , the composition can be molded into circuit board substrates using conventional molding equipment . the molded boards are then swelled and etched to promote the adhesion of copper by both roughening the surface and introducing chemical moieties through oxidation . the circuitry is then applied to the board by either a conventional additive or a semiadditive process . in either case copper is applied to the substrate in an electroless manner after the application of catalysts which activate the surface to the deposition of metal in a conventional manner . the following examples serve to give specific illustrations of the practice of this invention but they are not intended in any way to limit the scope of this invention . a polysulfone of the following formula ## str8 ## having a reduced viscosity of 0 . 43 as measured in chloroform ( 0 . 2 gram polymer in 100 ml at 25 ° c .) was injection molded into astm test bars ( at 270 °- 300 ° c .) using a newburg 1 / 4 ounce screw injection molding machine . the test bars were measured for the following properties : tensile strength and modulus according to astm d - 638 ; elongation at break according to astm d - 638 ; notched izod impact strength according to astm d - 256 ; tensile impact strength according to astm d - 1822 ; heat distortion temperature measured at 264 psi on a 1 / 8 inch thick unannealed test bar according to astm d - 638 ; melt flow according to astm d - 1238 - 73 and pendulum impact strength according to the following procedures : a sample one inch long by one - eighth inch wide ( 1 - 30 mils thick ) is mounted in the jaws such that it is transverse to the path of a pendulum and located at the bottom of the swing . the 1 / 8 inch face of the sample is impacted with the 1 / 4 inch diameter striking head of the pendulum . the pendulum is released from its starting position and allowed to swing through its cycle without a sample . the recovery height of zero energy loss is determined in this way . the cycle is repeated with a sample mounted in the path of the pendulum . the recovery height is again determined . since the breaking of the specimen extracted energy from the pendulum , the same recovery height is not attained . the difference in the recovery height ( i . e ., the difference in the potential energy of the pendulum at the maximum point of the upswing ) represents the energy absorbed by the specimen during rupture . the impact strength , expressed in foot - pounds per cubic inch , is obtained by dividing the pendulum energy loss by the volume of the specimen . five to ten specimens are tested for each material . a poly ( ether sulfone ) of the following formula ## str9 ## having a reduced viscosity of 0 . 48 ( as measured in n - methyl pyrrolidone at 25 ° c .) was injection molded into astm test bars and tested as described in control a . a blend of 90 weight percent of the poly ( ether sulfone ) of control b and 10 weight percent of the polysulfone of control a was prepared by extrusion blending in a single screw 1 - inch diameter extruder with l / d = 36 / 1 at 300 °- 320 ° c . the extrudate was chopped into pellets . the pellets were injection molded into astm test bars and tested as described in control a . the procedure of example 1 was exactly repeated except that 70 weight percent of the poly ( ether sulfone ) of control b and 30 weight percent of the polysulfone of control a were used . the procedure of example 1 was exactly repeated except that 50 weight percent of the poly ( ether sulfone ) of control b and 50 weight percent of the polysulfone of control a were used . the procedure of example 1 was exactly repeated except that 30 weight percent of the poly ( ether sulfone ) of control b and 70 weight percent of the polysulfone of control a were used . table i__________________________________________________________________________ tensile heatdescription of tensile notched izod impact distortion pendulum mf . sub . 10 mf . sub . 10the composition modu - tensile elon - impact strength strength temper - impact ( 350 ° c .) ( 400 ° mf . sub . 30poly - lus strength gation ( ft - lbs / ( ft - lbs / ature strength 44 psi . 44 ( 400 ° c .) mer . sup . 1 ( wt %) ( psi ) ( psi ) (%) ( in of notch ) in . sup . 2 ) (° c .) ( ft - lbs / in . sup . 3 ) ( dg / min ) ( dg / min ) 44__________________________________________________________________________ psi . a ps ( 100 ) 370 , 000 10 , 500 70 - 100 1 . 2 100 - 150 168 165 17 0b pes ( 100 ) 389 , 000 11 , 700 88 1 . 6 183 201 166 9 . 9 0 ps ( 10 ) 393 , 000 11 , 800 104 1 . 8 185 198 142 11 . 0 36 . 7 0 pes ( 90 ) ps ( 30 ) 391 , 000 11 , 500 88 1 . 6 181 190 208 13 . 8 36 . 1 0 pes ( 70 ) ps ( 50 ) 397 , 000 11 , 200 93 1 . 4 172 183 156 15 . 3 45 . 0 0 pes ( 50 ) c ps ( 70 ) 403 , 000 11 , 000 80 1 . 3 146 182 134 17 . 6 47 . 6 0 pes ( 30 ) __________________________________________________________________________ polysulfone = poly ( ether sulfone ) 70 weight percent of the polysulfone of control a was blended with 30 weight percent of fiberglass ( ocf - 197b made by owens corning fiberglass ) in a 1 - inch extruder with l / d = 24 / 1 at about 300 ° c . the extrudate was chopped into pellets . the pellets were injection molded into astm test bars and tested for the following properties : tensile strength and modulus according to astm d - 638 ; elongation at break according to astm d - 638 ; notched izod impact strength according to astm d - 256 ; tensile impact strength according to astm d - 1822 and heat distortion temperature measured at 264 psi on a 1 / 8 inch thick unannealed test bar according to astm d - 638 . the procedure of control d was exactly repeated except that 70 weight percent of the poly ( ether sulfone ) of control b was blended with 30 weight percent of the fiberglass described in control d . the procedure of control d was exactly repeated except that 50 weight percent of the poly ( ether sulfone ) of control b was blended with 20 weight percent of the polysulfone of control a and 30 weight percent of the fiberglass described in control d . the procedure of control d was exactly repeated except that 40 weight percent of the poly ( ether sulfone ) of control b was blended with 30 weight percent of the polysulfone of control a and 30 weight percent of the fiberglass described in control d . the procedure of control d was exactly repeated except that 35 weight percent of the poly ( ether sulfone ) of control b was blended with 35 weight percent of the polysulfone of control a and 30 weight percent of the fiberglass described in control d . the procedure of control d was exactly repeated except that 20 weight percent of the poly ( ether sulfone ) of control b was blended with 50 weight percent of the polysulfone of control a and 30 weight percent of the fiberglass described in control d . table ii__________________________________________________________________________ notched izod tensile heat description of tensile tensile impact strength impact distortion the composition modulus strength elongation ( ft - lbs / strength temperatureexample ingredients . sup . 1 ( wt %) ( psi ) ( psi ) (%) ( in of notch ) ( ft - lbs / in . sup . 2 ) (° c . ) __________________________________________________________________________control d ps ( 70 ) 1 , 240 , 000 17 , 900 1 . 9 1 . 8 69 182 fiberglass ( 30control e pes ( 70 ) 1 , 160 , 000 18 , 700 2 . 7 1 . 7 97 217 fiberglass ( 30 ) 4 pes ( 50 ) 1 , 250 , 000 20 , 400 2 . 5 2 . 0 93 215 ps ( 20 ) fiberglass ( 305 pes ( 40 ) 1 , 310 , 000 20 , 200 2 . 2 2 . 1 81 203 ps ( 30 ) fiberglass ( 30 ) 6 pes ( 35 ) 1 , 310 , 00 18 , 400 1 . 8 2 . 0 105 190 ps ( 35 ) fiberglass ( 30 ) control f pes ( 20 ) 1 , 260 , 000 19 , 200 2 . 1 2 . 0 74 185 ps ( 50 ) fiberglass ( 30 ) __________________________________________________________________________ . sup . 1 ps = polysulfone pes = poly ( ether sulfone ) the following examples 7 to 9 describe blends of polysulfone , poly ( ether sulfone ), filler and / or reinforcing agent . 40 weight percent of the polysulfone of control a was blended with 30 weight percent of the poly ( ether sulfone ) of control b and 30 weight percent of particulate wollastonite ( nyad n - 400 sold by nyco , a division of processed minerals , inc . in an extruder with l / d equal to 24 / 1 at 300 ° c . the extrudate was chopped into pellets . the pellets were injection molded into astm test bars and tested as described in control d . the procedure of example 7 was exactly repeated except that 35 weight percent of the polysulfone of control a was blended with 35 weight percent of the poly ( ether sulfone ) of control b and 30 weight percent of the wollastonite described in example 7 . the procedure of example 7 was exactly repeated except that 27 weight percent of the polysulfone of control a was blended with 41 weight percent of the poly ( ether sulfone ) of control b , 15 weight percent of the wollastonite described in example 7 , 15 weight percent of the fiberglass described in control d and 2 weight percent of zinc oxide stabilizer . __________________________________________________________________________ notched izod tensile heatdescription of tensile tensile impact strength impact distortionthe composition modulus strength elongation ( ft - lbs / strength temperatureexampleingredients . sup . 1 ( wt %) ( psi ) ( psi ) (%) in of notch ) ( ft - lbs / in . sup . 2 ) (° c . ) __________________________________________________________________________7 ps ( 40 ) 614 , 000 9 , 180 3 . 2 1 . 0 29 182pes ( 30 ) wollastonite ( 30 ) 8 ps ( 35 ) 628 , 000 9 , 180 2 . 9 0 . 9 25 183pes ( 35 ) wollastonite ( 30 ) 9 ps ( 27 ) 912 , 000 13 , 500 2 . 4 1 . 2 13 198pes ( 41 ) wollastonite ( 15 ) fiberglass ( 15 ) zno ( 2 ) __________________________________________________________________________ . sup . 1 ps = polysulfone pes = poly ( ether sulfone ) 65 weight percent of the polysulfone of control a was blended with 15 weight percent of the fiberglass of control d , 18 weight percent of the wollastonite of example 7 and 2 weight percent of zinc oxide stabilizer in a zsk - 53 werner pfleider twin screw extruder at 380 ° c . the extrudate was chopped into pellets . the material used for the circuit board was tested for the following properties ; tensile strength and modulus according to astm d - 638 ; flexural strength and modulus according to astm d - 790 ; elongation at break according to astm d - 638 ; tensile impact strength according to astm d - 1822 and the linear thermal expansion coefficient was measured according to astm d - 696 . the procedure of control g was exactly repeated except that 26 . 4 weight percent of the polysulfone of control a , 40 weight percent of the poly ( ether sulfone ) of control b , 15 weight percent of the fiberglass of control d , 16 . 6 weight percent of the wollastonite of example 7 , and 2 weight percent of zinc oxide were used . __________________________________________________________________________ tensile description of tensile tensile flexural flexural impact linear thermal the composition strength modulus strength modulus elongation strength expansion coeff . example ingredients . sup . 1 ( wt %) ( psi ) ( psi ) ( psi ) ( psi ) (%) ( ft - lb / sq (° c .. sup .- 1 × 10 . sup . 5 ) __________________________________________________________________________control g ps ( 65 ) 12 , 000 780 , 000 19 , 100 798 , 000 2 . 6 20 2 . 8 fiberglass ( 15 ) wollastonite ( 18 ) zno ( 2 ) 10 ps ( 26 . 4 ) 14 , 000 870 , 000 20 , 200 840 , 000 2 . 5 28 2 . 8 pes ( 40 ) fiberglass ( 15 ) wollastonite ( 16 . 6 ) zno ( 2 ) __________________________________________________________________________ ps = polysulfone pes = poly ( ether sulfone ) the materials of control g and example 10 were molded in an injection molding machine at 400 ° c . into a circuit board 31 / 2 × 5 inches . the boards were then annealed at 335 ° f . for four hours followed by swell and etch steps to promote copper adhesion . these steps consisted of a dip in a solution of approximately 7 percent by weight water in n , n ,- dimethyformamide at 80 ° f ., followed by a water rinse , then dipping in chromosulfuric acid at 170 ° f . the chromosulfuric acid bath had a composition such as : ______________________________________ percentage in mixturecomponent ( weight percent ) ______________________________________96 % h . sub . 2 so . sub . 4 55 . 985 - 87 % h . sub . 3 po . sub . 4 10 . 4cro . sub . 3 3 . 0h . sub . 2 o 30 . 7______________________________________ following the etchant , the board was plated with copper by an additive process which consists of chemically sensitizing the substrate , photographically imaging the circuitry , developing the image and plating electroless copper to form the electrically conductive network . finished boards were then soldered using conventional wave soldering equipment at several speeds using commercial water soluble and freon based solder fluxes . boards molded from the material in example 10 were solderable at temperatures as high as 495 ° f . while those molded from the material in control g were not solderable above 460 ° f ., since above these temperatures the copper separated from the substrate surface resulting in failure . materials of controls a , b and c , and examples 1 , 2 and 3 were compression molded in a 20 mil 4 × 4 inch cavity mold at 300 ° c . into films 20 mils thick . their 1 percent secant moduli were measured according to a procedure similar to astm d - 638 between 25 ° and 250 ° c . as the temperature rose the moduli of the materials decreased . the temperatures at which the moduli decreased to 1000 psi are shown in fig1 . if the composition contains between 40 and 90 weight percent of poly ( ethersulfone ), much higher temperatures can be reached with the modulus above 1000 psi as compared with those that can be reached with the polysulfone of control a .