A method of manufacturing a printed circuit board (PCB) having at least one conductive layer and at least one non-conductive layer and forming a first surface and a second surface , said method comprising: disposing a plurality of vias through the PCB to connect the surfaces , wherein each via includes a metallic portion having a pair of ends and defining a hole and wherein the plurality of vias includes at least one thermal transfer via for conduction of heat between the surfaces and at least one electrical via for conduction of electrical current between the surfaces ; filling the hole of each via with a solder mask to a given level between the ends , wherein said step of filling the hole of each via with a solder mask is further defined as filling the hole of the at least one electrical via with a solder mask to a level of 100 percent of the height of the electrical via and partially filling the hole of the at least one thermal transfer via with a solder mask , wherein the solder mask is also applied to portions of the first and/or second surface of the PCB to provide electrical insulation to the portions of the surfaces , characterized by : coating at least a portion of one of the surfaces of the PCB with an organic solderability preservative (OSP) in response to said step of filling the hole of each via ; and removing the organic solderability preservative (OSP) from the hole of the at least one thermal transfer via in response to the application of the organic solderability preservative (OSP) . disposing a plurality of vias through the PCB to connect the surfaces , wherein each via includes a metallic portion having a pair of ends and defining a hole and wherein the plurality of vias includes at least one thermal transfer via for conduction of heat between the surfaces and at least one electrical via for conduction of electrical current between the surfaces ; filling the hole of each via with a solder mask to a given level between the ends , wherein said step of filling the hole of each via with a solder mask is further defined as filling the hole of the at least one electrical via with a solder mask to a level of 100 percent of the height of the electrical via and partially filling the hole of the at least one thermal transfer via with a solder mask , wherein the solder mask is also applied to portions of the first and/or second surface of the PCB to provide electrical insulation to the portions of the surfaces , characterized by : coating at least a portion of one of the surfaces of the PCB with an organic solderability preservative (OSP) in response to said step of filling the hole of each via ; and removing the organic solderability preservative (OSP) from the hole of the at least one thermal transfer via in response to the application of the organic solderability preservative (OSP) . coating at least a portion of one of the surfaces of the PCB with an organic solderability preservative (OSP) in response to said step of filling the hole of each via ; and removing the organic solderability preservative (OSP) from the hole of the at least one thermal transfer via in response to the application of the organic solderability preservative (OSP) . <EOS>