Circuit board and method for manufacturing the same

A method for manufacturing a circuit board comprising:

• providing a substrate and forming a first wiring layer on the substrate;
• forming an adhesive layer on the substrate, and the first wring layer is exposed from the adhesive layer, wherein a thickness of the adhesive layer is less than a thickness of the first wiring layer, a portion of the first wiring layer is embedded in the adhesive layer, and a remaining portion of the first wiring layer protrudes from the adhesive layer;
• forming a build-up structure on a side of the adhesive layer facing away from the substrate, the build-up structure covering the first wiring layer and the adhesive layer, wherein the build-up structure comprises at least one dielectric layer and at least one second wiring layer, each of the at least one dielectric layer and each of the at least one second wiring layer are alternately arranged, the at least one dielectric layer comprises an outermost dielectric layer covering the first wiring layer, and infilling in a gap of the first wiring layer protruding from the adhesive layer, the remaining portion of the first wiring layer protruding from the adhesive is embedded in the outermost dielectric layer, the at least one second wiring layer is formed on a side of the outermost dielectric layer away from the substrate, and comprises an outermost second wiring layer;
• and
• removing the substrate and the adhesive layer, wherein the portion of the first wiring layer embedded in the adhesive layer is exposed and protruding from the outermost dielectric layer, wherein after removing the substrate and the adhesive layer, the method further comprises:
• forming a solder mask on the first wiring layer and the outermost second wiring layer of the build-up structure, wherein the solder mask infills in a gap of the first wiring layer protruding from the outermost dielectric layer, and infills in a whole gap of the outermost second wring layer of the build-up structure;
• defining at least one first opening on the solder mask adjacent to the first wiring layer and at least one second opening on the solder mask adjacent to the outermost second wring layer of the build-up structure, wherein the first wiring layer comprises at least one first connecting pad, a portion of each of the at least one first connecting pad protruding from the outermost dielectric layer is entirely exposed from the at least one first opening.