The present invention provides an entry sheet for drilling excellent in hole position accuracy compared with the conventional entry sheet for drilling. Such an entry sheet for drilling is an entry sheet for drilling comprising metallic support foil and a layer comprising a resin composition formed on at least one surface of the metallic support foil, in which the resin composition contains a resin and 70 parts by mass to 130 parts by mass of molybdenum disulfide based on 100 parts by mass of the resin, and the layer comprising the resin composition has a thickness in a range from 0.02 to 0.3 mm.

An entry sheet for drilling comprising: a metallic foil; and a layer of a resin composition on at least one surface of the metallic foil, the resin composition comprising a polyolefin resin (A) and a water-soluble resin (B), wherein a content of the polyolefin resin (A) is 25 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the total of the polyolefin resin (A) and the water-soluble resin (B), a content of the water-soluble resin (B) is 50 parts by mass or more and 75 parts by mass or less based on 100 parts by mass of the total of the polyolefin resin (A) and the water-soluble resin (B), and the water-soluble resin (B) comprises a high-molecular-weight water-soluble resin (B-1) having a weight average molecular weight of 210.sup.5 or higher and 1.510.sup.6 or lower.

The present invention enables the manufacture of a small-sized high-density multi-layer printed circuit board. The manufacturing method for a multi-layer printed circuit board, according to the present invention, comprises: a step in which an electrical insulation layer is formed by heating a laminate comprising a substrate, a heat-curable resin composition layer provided on the substrate, and a release substrate provided on the heat-curable resin composition layer, thereby curing the heat-curable resin composition layer, and a step in which a via hole is formed in the electrical insulation layer by irradiating a laser from above the release substrate. In addition, in the present invention, the release substrate has a thickness of at least 80 m and is formed using a material having a glass transition temperature, the heat-curable resin composition layer has a volatile component-content of 7.0 mass % or less and a thickness of 25 m or less, and the curing of the heat-curable resin composition layer occurs at a temperature that is not less than the glass transition temperature of the material of the release substrate.

A process for the production of an entry sheet for drilling a printed wiring board material, which process comprises forming a multi-layered water-soluble resin composition layer on at least one surface of a metal foil, wherein an aqueous solution of a water-soluble resin composition is applied to the metal foil, dried and solidified to form one water-soluble resin composition layer, the application, drying and solidification of the aqueous solution of the water-soluble resin composition are repeated at least once to form at least one water-soluble resin composition layer on the above one water-soluble resin composition layer, the multi-layered water-soluble resin composition layer is composed of these water-soluble resin composition layers, the multi-layered water-soluble resin composition layer has a thickness of at least 50 m and is almost free from air bubbles, and an entry sheet for drilling a printed wiring board material obtained by the above process.

A burr-suppressing copper foils are described. In an embodiment, the burr suppressing copper foil includes a poly-based film having an adhesive on a first side and an adhesive on a second side. A copper foil contacts the adhesive at the first side of the poly-based film to removably couple the poly-based film to the copper foil. A metallic burr suppressor contacts the adhesive on the second side to removably couple the poly-based film to the metallic burr suppressor.

Entry sheet for drilling including a metallic foil and a layer of a resin composition, the layer formed on the metallic foil without interposing an adhesion layer, in which the layer of the resin composition has a peak attributable to a carbon atom-oxygen atom double bond appearing at 1700 to 1750 cm.sup.1 and a peak attributable to a carbon atom-oxygen atom single bond appearing at 1080 to 1300 cm.sup.1 in infrared spectroscopy, and when the absorbance at the peak attributable to the carbon atom-oxygen atom double bond appearing at 1700 to 1750 cm.sup.1 is represented by Abs(CO)L, and the absorbance at the peak of the carbon atom-oxygen atom single bond appearing at 1080 to 1300 cm.sup.1 is represented by Abs(CO)L, the layer of the resin composition has an absorbance ratio (C) of 0.12 to 1.80, the absorbance ratio (C) represented by the following expression (1).

Absorbance ratio(C)=Abs(CO)L/Abs(CO)L Expression (1)

An entry sheet for drilling comprising: a metallic foil; and a layer of a resin composition, the layer formed on the metallic foil without interposing an adhesion layer, wherein the surface of the layer of the resin composition, the surface being in contact with the metallic foil, has a dispersion term SD of surface free energy in a range from 27.0 to 37.0 mJ/m.sup.2 and a polar term SP of the surface free energy in a range from 0 to 5.0 mJ/m.sup.2.

A method for manufacturing a back drilling hole in a printed circuit board (PCB) and PCB are provided. The method for manufacturing the back drilling hole comprises: forming a through hole in the PCB (1); forming a metal layer (12) with prescribed thickness on an inner wall of the through hole; filling resin in the through hole which has been formed with the metal layer (12); performing back drilling machining on the through hole which has been filled with the resin; removing metal scraps remained in the through hole. The manufacturing method protects the hole wall copper by filling the hole with the resin, so that acid corrosion process only removes the remained metal scraps after back drilling of the small hole, does not affect on the hole copper of the resin protecting portion.

The present invention provides an entry sheet for drilling which provides higher hole position accuracy than that of a conventional entry sheet for drilling. The present invention provides an entry sheet for drilling, including a metal foil, and a layer including a resin composition and formed on at least one surface of the metal foil, wherein the resin composition includes a resin and tungsten disulfide as a solid lubricant, and the content of the tungsten disulfide included in the resin composition is 10 parts by mass to 200 parts by mass based on 100 parts by mass of the resin included in the resin composition.

A PCB backup plate preparation method comprises: lubricating and radiating resin is coated onto both surfaces of the wood fiberboard and a resin layer forms, before it is totally dried out, wood pulp paper is bonded to its surfaces, then, the surface of the wood pulp paper is coated with unsaturated polyester resin and forms a resin layer, and the PCB backup plate is prepared; the lubricating and radiating resin is prepared by a 95 weight portion of principal component, composed by two or more of polyethylene oxide, polyethylene glycol, glycerol, vinyl acetate and polyvinyl alcohol, and a 5 portion of nonionic surfactant. The lubricating and radiating resin brings the PCB good lubricating and radiating capabilities, therefore increases the drilling hole accuracy when starts to drill, improves the hole wall quality and lowers the drill pin temperature.