The cast-in bake/chill platen heater for semiconductor processing has essentially the same operating specifications as the cast-in bake platen with the addition of a cooling function. A precision formed cooling tube is added as an integral component to the heater assembly in the body of the casting. This function can be used to rapidly cool the working surface of the cast-in platen or act as a heat exchanger for liquids or gases. A pressure test on the finished part assures the integrity of the cooling tube after the casting process. Various termination options are available to customize the cooling tube exits to existing or new applications.