本发明揭示一种封装基板之制作方法，其步骤包含：提供一承载板；形成一第一介电材料层于该承载板上，并图案化该第一介电材料层，使得一开口区形成于该第一介电材料层内，借以露出该承载板；形成一第一导电单元于该承载板上，使得位于该开口区的该第一导电单元之高度大于该第一介电材料层之厚度，并使得位于该第一介电材料层之上的该第一导电单元之宽度大于该开口区之宽度；形成一第二介电材料层于该第一导电单元上；形成一第二导电单元于该第二介电材料层上；形成一第三介电材料层于该第二导电单元上；移除该承载板，并移除该第一导电单元位于该开口区内的部分；以及形成一第四介电材料层，使其包覆该第才导电单元。

This disclosure provides a method of fabricating package substrates, which includes steps of: provide a carrier substrate; forming a first dielectric material layer on the carrier substrate and patterning the first dielectric material layer to form an opening exposing the carrier substrate in the first dielectric material layer; forming a first conducting unit on the carrier substrate, so that a height of the first conducting unit in the opening is larger than a thickness of the first dielectric material layer and a width of the first conducting unit on the first dielectric material layer is larger than a width of the opening; forming a second dielectric material layer on the first conducting unit; forming a second conducting unit on the second dielectric material layer; forming a third dielectric material layer on the second conducting unit; removing the carrier substrate and a part of the first conducting unit in the opening; and forming a fourth dielectric material layer to cover the first conducting unit.