Patent ID: 6988312
Filing Date: 2006-01-24
Classification: H01L,H05K,Y10T

Abstract:
1. A method for producing a multilayer circuit board for a semiconductor device, the multilayer circuit board having a multilayer circuit board body formed of predetermined numbers of wiring line layers and insulating layers, and having a side for mounting a semiconductor element thereon and another side for external connecting terminals, the side for mounting a semiconductor element being provided with pads through which the multilayer circuit board is connected to the semiconductor element to be mounted, and the side for external connecting terminals being provided with pads through which the multilayer circuit board is connected to external electrical circuits, and the multilayer circuit board body being provided, on the side for mounting a semiconductor element, with a frame surrounding an area for mounting the semiconductor element thereat, the method comprising: fabricating a composite metal sheet by combining two metal sheet face to face with each other, forming, on each of the sides of the composite metal sheet, pads for connecting to a semiconductor element, the pads being made of a metal material which is substantially not etched by an etchant for the metal sheet, and an insulating layer having openings exposing the pads, forming, on the insulating layer, a wiring line layer connecting to the pads through the openings, the wiring line layer being provided with pads for connecting to another wiring line layer to be subsequently formed, carrying out, a required number of times, the step of forming an insulating layer having openings exposing the pads for connecting to the another wiring line layer, and a wiring line layer connecting through the openings to pads of the another wiring line layer, which is located under the insulating layer, and being provided with pads for connecting to still another wiring line layer to be subsequently formed or pads for external connecting terminals, to fabricate a multilayer circuit board body having the predetermined numbers of wiring line layers and insulating layers, forming, on the outermost insulating layer of the multilayer circuit board body, an insulating layer provided with through-holes exposing the pads for external connecting terminals, which are located on the outermost insulating layer, dividing the composite metal sheet, to yield intermediates each provided on one side of the metal sheet with the multilayer circuit board body, and etching the metal sheet at an area at which a semiconductor element is to be positioned for the mounting thereof to remove the material of the metal sheet at that area, to thereby form a frame surrounding the area for the mounting of the semiconductor element.