Method for fabricating a packaging substrate

Abstract

A method for fabricating a packaging substrate includes: stacking two metal layers; encapsulating the two metal layers with assistant dielectric layers; forming built-up structures on the assistant dielectric layers, respectively; and separating the built-up structures along the interface between the two metal layers so as to form two packaging substrates. Owing to the adhesive characteristic of the assistant dielectric layers, the two metal layers are unlikely to separate from each other during formation of the built-up structures. But after portions of the dielectric layer around the periphery of the metal layers are cut and removed, the two metal layers can be readily separated from each other. The two metal layers can be patterned to form wiring layers, metal bumps, or supporting structures to avoid waste of materials. A packaging substrate and a fabrication method thereof are provided.

1 - 4 . (canceled) 
     
     
         5 . A method for fabricating a packaging substrate, comprising the steps of:
 providing a base material comprising two first metal layers each having a first surface and an opposed second surface and stacked together with the first surfaces thereof facing each other, two first assistant dielectric layers disposed on the second surfaces of the first metal layers, respectively, and encapsulating the first metal layers, and two second metal layers disposed on exposed surfaces of the first assistant dielectric layers, respectively;   patterning the second metal layers to form inner wiring layers; and   forming built-up structures on the first assistant dielectric layers and the inner wiring layers to form an overall structure, wherein the built-up structures each comprise at least a first dielectric layer, a first wiring layer formed on the first dielectric layer, and a plurality of first conductive vias formed in the first dielectric layer and electrically connecting to the first wiring layer and the inner wiring layer.   
     
     
         6 . The method of  claim 5 , wherein the first surfaces of the first metal layers are smooth surfaces and the second surfaces of the first metal layers are rough surfaces. 
     
     
         7 . The method of  claim 5 , wherein fabrication of the base material comprises the steps of:
 providing the two first metal layers each having a first surface and an opposed second surface, and stacking the two first metal layers together with the first surfaces thereof facing each other;   stacking the first assistant dielectric layers on the second surfaces of the first metal layers; and   stacking the second metal layers on the exposed surfaces of the first assistant dielectric layers, followed by laminating together the first metal layers, the first assistant dielectric layers and the second metal layers such that the two first assistant dielectric layers are bonded together to encapsulate the two first metal layers.   
     
     
         8 . The method of  claim 5 , further comprising cutting the overall structure along edges passing through the first metal layers so as to separate the first metal layers from each other, thereby forming two initial substrates. 
     
     
         9 . The method of  claim 5 , wherein the first wiring layers disposed on an outermost portion of the built-up structures have a plurality of first conductive pads, and first insulating protective layers are formed on the built-up structures and formed therein with a plurality of openings corresponding in position to the first conductive pads, respectively, so as for the first conductive pads to be exposed from the insulating protective layers. 
     
     
         10 . The method of  claim 5 , further comprising patterning the first metal layers so as to form second wiring layers, and forming in the first assistant dielectric layers a plurality of second conductive vias electrically connecting the inner wiring layers and the second wiring layers, wherein the second wiring layers have a plurality of second conductive pads, wherein second insulating protective layers are formed on the first assistant dielectric layers, and a plurality of openings corresponding in position to the second conductive pads, respectively, are formed in the second insulating protective layers so as for the second conductive pads to be exposed from the second insulating protective layers. 
     
     
         11 . The method of  claim 5 , wherein the first wiring layers disposed on an outermost portion of the built-up structures have a plurality of first conductive pads, and the method further comprises the steps of:
 forming first insulating protective layers on the built-up structures and forming in the first insulating protective layers a plurality of openings corresponding in position to the first conductive pads, respectively, so as for the first conductive pads to be exposed;   cutting the overall structure along edges passing through the first metal layers; and   separating the first metal layers from each other so as to form two initial substrates.   
     
     
         12 . The method of  claim 11 , further comprising removing the first metal layers to expose the first assistant dielectric layers, and forming a plurality of openings in the first assistant dielectric layers to expose portions of the inner wiring layers. 
     
     
         13 . A method for fabricating a packaging substrate, comprising the steps of:
 providing a base material comprising two first metal layers each having a first surface and an opposed second surface and stacked together with the first surfaces thereof facing each other, two first assistant dielectric layers formed on the second surfaces of the first metal layers, respectively, and encapsulating the first metal layers, and two second metal layers formed on the exposed surfaces of the first assistant dielectric layers, respectively;   patterning the second metal layers to form inner wiring layers, and forming in the first assistant dielectric layers a plurality of inner conductive vias electrically connecting the inner wiring layers and the first metal layers;   forming built-up structures on the first assistant dielectric layers and the inner wiring layers, wherein the built-up structures each comprise at least a first dielectric layer, a first wiring layer formed on the first dielectric layer, and a plurality of first conductive vias formed in the first dielectric layer and electrically connecting the first wiring layer and the inner wiring layer, and the first wiring layers disposed on an outermost portion of the built-up structures have a plurality of first conductive pads;   forming first insulating protective layers on the built-up structures to form an overall structure, and forming in the first insulating protective layers a plurality of openings corresponding in position to the first conductive pads, respectively, so as for the first conductive pads to be exposed from the first insulating protective layers;   cutting the overall structure along edges passing through the first metal layers; and   separating the first metal layers from each other so as to form two initial substrates.   
     
     
         14 . The method of  claim 13 , wherein the first surfaces of the first metal layers are smooth surfaces and the second surfaces of the first metal layers are rough surfaces. 
     
     
         15 . The method of  claim 13 , wherein fabrication of the base material comprises the steps of:
 providing the two first metal layers each having a first surface and an opposed second surface, and stacking the first metal layers together with the first surfaces thereof facing each other;   stacking the first assistant dielectric layers on the second surfaces of the first metal layers; and   stacking the second metal layers on the exposed surfaces of the first assistant dielectric layers, followed by laminating together the first metal layers, the first assistant dielectric layers and the second metal layers such that the two first assistant dielectric layers are bonded together to encapsulate the two first metal layers.   
     
     
         16 . The method of  claim 13 , further comprising removing portions of the first metal layers so as to form a plurality of metal bumps connected to the inner conductive vias, respectively. 
     
     
         17 . The method of  claim 16 , further comprising forming metal support frames on the first assistant dielectric layers. 
     
     
         18 . A method for fabricating a packaging substrate, comprising the steps of:
 providing a base material comprising two first metal layers each having a first surface and an opposed second surface and stacked together with the first surfaces thereof facing each other, two first assistant dielectric layers formed on the second surfaces of the first metal layers, respectively, and encapsulating the first metal layers, two core layers formed on the exposed surfaces of the first assistant dielectric layer, respectively, two second assistant dielectric layers formed on the exposed surfaces of the core layers, respectively, and two second metal layers formed on the exposed surfaces of the second assistant dielectric layers, respectively, wherein the two surfaces of each of the core layer have a plurality of first conductive lands and a plurality of second conductive lands, respectively, and the second conductive lands are positioned on the first assistant dielectric layers;   patterning the second metal layers to form inner wiring layers, and forming in the second assistant dielectric layers a plurality of inner conductive vias electrically connecting the inner wiring layers and the first conductive lands;   forming built-up structures on the second assistant dielectric layers and the inner wiring layers so as to form an overall structure, wherein the built-up structures each comprise at least a first dielectric layer, a first wiring layer formed on the first dielectric layer, and a plurality of first conductive vias formed in the first dielectric layer and electrically connecting the first wiring layer and the inner wiring layer;   cutting the overall structure along edges passing through the first metal layers; and   separating the first metal layers from each other so as to form two initial substrates.   
     
     
         19 . The method of  claim 18 , wherein the first surfaces of the first metal layers are smooth surfaces and the second surfaces of the first metal layers are rough surfaces. 
     
     
         20 . The method of  claim 18 , wherein fabrication of the base material comprises the steps of:
 providing the two first metal layers each having a first surface and an opposed second surface and stacked together with the first surfaces thereof facing each other, the two first assistant dielectric layers formed on the second surfaces of the first metal layers, the two core layers formed on the exposed surfaces of the first assistant dielectric layers, the two second assistant dielectric layers formed on the exposed surfaces of the core layers, and the two second metal layers formed on the exposed surfaces of the second assistant dielectric layers; and   laminating together the first metal layers, the first assistant dielectric layers, the core layers, the second assistant dielectric layers and the second metal layers such that the two first assistant dielectric layers are bonded together to encapsulate the two first metal layers, and the second conductive lands are embedded in the first assistant dielectric layers.   
     
     
         21 . The method of  claim 18 , wherein the first wiring layers disposed on an outermost portion of the built-up structures have a plurality of first conductive pads, and first insulating protective layers are formed on the built-up structures and formed therein with a plurality of openings corresponding in position to the first conductive pads, respectively, so as for the first conductive pads to be exposed from the first insulating protective layers. 
     
     
         22 . The method of  claim 18 , further comprising patterning the first metal layers so as to form second wiring layers, and forming in the first assistant dielectric layers a plurality of second conductive vias electrically connecting the second conductive lands and the second wiring layers, wherein the second wiring layers further has a plurality of second conductive pads, wherein second insulating protective layers are formed on the first assistant dielectric layers, and a plurality of openings corresponding in position to the second conductive pads, respectively, are formed in the second insulating protective layers so as for the second conductive pads to be exposed from the second insulating protective layers.