Provided is an entry sheet for drilling that, compared with a conventional entry sheet for drilling, has better hole position accuracy, can suppress drill bit breakage, and exhibits less processing chips wrapping around the drill bit. This entry sheet for drilling includes a metallic support foil and a layer comprising a resin composition that is formed on at least one surface of the metallic support foil, wherein the resin composition contains a cellulose derivative (A) and a water-soluble resin (B), the cellulose derivative (A) includes a hydroxyalkyl cellulose and/or a carboxyalkyl cellulose having a weight average molecular weight of 20,000 to 350,000, and based on 100 parts by mass of the resin composition, the content of the cellulose derivative (A) is 5 to 40 parts by mass and the content of the water-soluble resin (B) is 60 to 95 parts by mass.

Back drilling vias of a PCB, including: identifying a particular diameter of a particular via of multiple vias of the PCB; back drilling of the particular via with a first drill bit having a first diameter, the first diameter a first percentage greater than the particular diameter of the particular via; determining whether the first diameter of the first drill bit is a threshold percentage greater than the particular diameter of the particular via; determining that the first diameter of the first drill bit is less than the threshold percentage greater than the particular diameter of the particular via, and in response: back drilling of the particular via with a second drill bit having a second diameter, the second diameter a second percentage greater than the particular diameter of the particular via, the second diameter greater than the first diameter.

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 2×10.sup.5 or higher and 1.5×10.sup.6 or lower.

A burr-suppressing copper foil is 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.

A burr-suppressing copper foil is described. In an embodiment, the burr-supressing 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.

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.

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.

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.

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.