A circuit board structure includes an inner circuit structure and a first build-up circuit structure. The inner circuit structure includes a core layer having an upper surface and a lower surface, a first patterned circuit layer disposed on the upper surface, a second patterned circuit layer disposed on the lower surface and a conductive through hole connecting the first and the second patterned circuit layers. The first build-up circuit structure at least has a cavity and an inner dielectric layer. The inner dielectric layer has an opening connecting the cavity and exposing a portion of the first patterned circuit layer. A hole diameter of the opening is smaller than a hole diameter of cavity. A height difference is between an inner surface of the inner dielectric layer exposed by the cavity and a top surface of the first patterned circuit layer exposed by the opening.

Disclosed are a printed circuit board and a method for manufacturing the same. The printed circuit board includes a core insulating layer, at least one via formed through the core insulating layer, an inner circuit layer buried in the core insulating layer, and an outer circuit layer on a top surface or a bottom surface of the core insulating layer, wherein the via includes a first part, a second part below the first part, a third part between the first and second parts, and at least one barrier layer including a metal different from a metal of the first to third parts. The inner circuit layer and the via are simultaneously formed so that the process steps are reduced. Since odd circuit layers are provided, the printed circuit board has a light and slim structure.

Provided herein is a carrier-attached copper foil having desirable fine circuit formability. The carrier-attached copper foil includes a carrier, an interlayer, and an ultrathin copper layer in this order, wherein D2-D1 is 0.30 to 3.83 m, where D1 is the gravimetrically measured thickness of the carrier-attached copper foil excluding the carrier and the interlayer, and D2 is the maximum thickness of the layer remaining on a bismaleimide-triazine resin substrate in case of detaching the carrier after the carrier-attached copper foil is laminated to the resin substrate from the ultrathin copper layer side by being heat pressed under a pressure of 20 kgf/cm.sup.2 at 220 C. for 2 hours.

The present invention has the following configuration. The present invention relates to a low-loss flat cable signal line for an ultra-high frequency, wherein the signal line plated, by a manufacturing method using an electroplating bath, on a micro circuit pattern part formed in a cylindrical circuit mold configured in the electroplating bath is configured to have an arc-shaped cross section or oval-shaped cross section, and a ratio (=a/b) between an electroplated line width (b) and a micro circuit pattern part line width (a) is 0.3 or less.