Method of fabricating a packaging substrate including a carrier having two carrying portions

A method of fabricating a packaging substrate, comprising:

• providing a carrier having two carrying portions, each of the carrying portions having a first side and a second side opposite to the first side with a first metal layer and a second metal layer formed on an entirety of the first side and an entirety of the second side, respectively, and the carrying portions being bonded together through the second sides thereof, wherein the carrying portions are bonded through the second metal layers with the second metal layers being in direct contact with each other;
• after providing the carrier, forming a preliminary metal layer on each of the first metal layers;
• after forming the preliminary metal layer on each of the first metal layers, forming a single circuit layer from each of the preliminary metal layers on the first side of each of the carrying portions, wherein the single circuit layer is in direct contact with the first metal layer;
• and
• after forming the single circuit layer from each of the preliminary metal layers on the first side of each of the carrying portions, separating the carrying portions from each other to form two packaging substrates, wherein the first metal layer and the second metal layer are intact after forming the two packaging substrates.