Abstract: The amount of time required to manufacture double-sided printed circuit boards that contain conductor bridges can be reduced. A method is provided which includes the steps of forming holes which pass through an insulating board and a first conductor layer formed on a first main side of the insulating board, bonding a second conductor layer to a second main side of the insulating board having the holes, forming a third conductor layer on the whole first main side of the insulating board after bonding the second conductor layer, masking preset holes with a plating resist, plating the first conductor and holes in the insulating board, patterning the first conductor layer to form a first conductor pattern, patterning said second conductor layer to form a second conductor pattern, and removing the plating resist and the third conductor layer from an area which is covered with the plating resist.

Abstract: This invention reduces the amount of time required to manufacture double-sided printed circuit boards that contain conductor bridges.

Abstract: A welding nut comprising a main cylindrical body having a bearing surface end and an axial screw hole, a flange set around an outer perimeter of the body at the bearing surface end, and axially extending protrusions formed by partially pressed the flange in a direction towards the bearing surface. The protrusions extend axially beyond the bearing surface for resistance welding. At least one groove can be formed in the bearing surface between the screw hole and the protrusions. A guide tube having an external diameter smaller than an external diameter of the body can extend axially from the bearing surface. Screw threads can be bored continuously through the screw hole of the cylindrical body and an inner perimeter of the guide tube. A large number of serrated protrusions can be formed on an outer perimeter of the cylindrical body. Each of the protrusions can have an inner surface slanting radially outwardly and axially away from the bearing surface towards an outer edge of the flange.