Method for fabricating core substrate using paste bumps

A core substrate and multilayer printed circuit board using paste bumps and manufacturing method thereof are disclosed. With the method of manufacturing a core substrate using paste bumps comprising: (a) aligning a pair of paste bump boards, each of which has a plurality of paste bumps joined to its surface, such that the paste bumps face each other, and (b) pressing the pair of paste bump boards together, where an insulation element is placed between the pair of paste bump boards, it is easier to implement interlayer electrical interconnection between circuit patterns, the thickness of the core substrate can readily be adjusted by adjusting the thickness of the insulation layer, the stiffness is improved as a pair of paste bump boards are pressed from the top and bottom, and high-density wiring can be formed more easily as the paste bumps are connected in pairs so that the diameters of the paste bumps formed on the paste bump boards can be reduced.