Patent ID: 6931724
Filing Date: 2005-08-23
Classification: H01L,H05K,Y10T

Abstract:
1. The method of producing a substrate of multilayered structure having leads for mounting a semiconductor element thereon, which comprises the following steps: (a) providing a metal sheet, (b) forming, on the metal sheet, a plurality of pads to be bonded to an electrode terminal of the semiconductor element, (c) forming a first layer of insulating material on the metal sheet so as to cover the pads formed thereon, said first layer of insulating material forming a face comprising pads to be bonded to an electrode terminal of the semiconductor element, (d) piercing the layer of insulating material to form holes which expose the end face of the pad, the holes providing the boundaries for vias which pierce through the insulation layer so as to have a bottom at the side of the insulation layer facing the face of the substrate for mounting a semiconductor element, (e) forming a patterned metal layer to provide a layer of wiring lines which includes wiring lines formed on the layer of insulating material and vias, the vias connecting the respective pad in the hole with the wiring line on the layer of insulation material, (f) forming a layer of insulation material to cover the layer of wiring line, (g) piercing the layer of insulating material formed in step (f) to form holes which expose part of the underlying wiring line, (h) forming a patterned metal layer to provide a layer of wiring lines which includes wiring lines formed on the layer of insulating material and vias, the vias connecting the parts of the wiring line exposed in step (g) with the wiring line on the layer of insulation material, (i) repeating steps (f) to (h) until the predetermined number of sets of an insulation layer and a wiring line layer is obtained, the wiring line layers and the insulation layers being alternately laminated from the face for mounting a semiconductor element thereon to a second face on which external connection terminal are to be provided, and (j) removing the metal sheet from the sets of an insulation layer and a wiring line layer formed thereon, wherein said last insulation layer formed thereon provides a second face adapted to have external connection terminals formed thereon, and (k) forming pads on the second face, said pads to be bonded to an external connection terminal, thereby forming a substrate having the first face for mounting the semiconductor element thereon, a plurality of sets of an insulation layer and a wiring line layer, wherein the plurality of sets of an insulation layer and a wiring line layer are successively formed from the side of the multilayered substrate at which the face for mounting a semiconductor element is located to the second side of the multilayered substrate, and the second face on which external connection terminals are to be provided, wherein the wiring line layers on both sides of an insulation layer being connected with each other by vias piercing the insulation layer, the vias being formed to pierce through the insulation layer so as to have a bottom at the side of the insulation layer facing the face of the substrate for mounting a semiconductor element and an opening at the side of the insulation layer on which external connection terminals are to be provided.