Method for manufacturing multi-layer package substrates

A method for manufacturing multi-layer package substrates, comprising the steps of:

• providing a substrate that has a first side and a second side which are respectively laminated to a first release film;
• drilling said substrate bonded to said first release film to form a plurality of through holes;
• plugging said through holes with a conductive material and forming bulged objects on said substrate, and removing said bulged objects before said conductive material is cured and hardened;
• removing said first release film;
• forming a first copper film on said first side and said second side of said substrate;
• performing photolithography and etching processes on said copper film to form a plurality of first circuit layer patterns on said first side and said second side of said substrate;
• coating said first side and said second side of said substrate to form an build-up layer;
• drilling said build-up layers through means of a laser to form a plurality of counter vias on said first side and said second side of the substrate, each of said counter vias exposing one of the first circuit layer patterns;
• forming a copper seed layer on the inner surfaces of said counter vias, the surfaces of said first circuit layer patterns and the surfaces of said build-up layers;
• performing photolithography and etching processes on said copper seed layer to form second circuit layer patterns;
• and
• forming contact pads on said second circuit layer patterns.