A board for mechanically supporting and electrically connecting electronic components includes a non-conductive substrate, a plurality of electrically conductive traces and pads disposed on the non-conductive substrate, and a solder mask applied to the non-conductive substrate and covering the traces. Metal lines are disposed on the non-conductive substrate under the solder mask and along at least two sides of the pads disposed in corners of the non-conductive substrate, so that a metal line is interposed between the pads in the corners of the non-conductive substrate and each adjacent pad. The metal lines form a raised region in the solder mask along the metal lines which prevents solder bridging in the corners of the non-conductive substrate during solder reflow. A corresponding semiconductor package and semiconductor assembly with such solder bridging prevention structures are also provided.