Printed circuit board

A printed circuit hoard, comprising:

• an insulating layer having a through-hole;
• a conductive layer laminated on at least an inner circumferential surface of the through-hole of the insulating layer;
• and
• metal plating layers laminated on a surface of the conductive layer facing opposite the insulating layer and laminated on both surfaces of the insulating layer,
• wherein an average thickness of the insulating layer is greater than or equal to 5 μm and less than or equal to 50 μm,
• wherein an average thickness of the conductive layer is greater than or equal to 0.05 μm and less than or equal to 0.5 μm,
• wherein an average thickness of the metal plating layers is greater than or equal to 3 μm and less than or equal to 50 μm,
• wherein a hole diameter of the through-hole, gradually increases from a first end of the through-hole at one surface of the insulating layer to a second end of the through-hole at another surface of the insulating layer,
• wherein the hole diameter of the through-hole at the first end thereof is greater than or equal to 1.7 times, and less than or equal to 2.3 times, the average thickness of either one of the metal plating layers laminated on both surfaces of the insulating layer,
• wherein the hole diameter of the through-hole at the second end thereof is greater than or equal to 1.1 times, and less than or equal to 2 times, the hole diameter of the through-hole at the first end thereof, and
• wherein the metal plating layers include a first portion disposed in contact with the one surface of the insulating layer, a second portion disposed at the first end of the through-hole, a third portion disposed at the second end of the through-hole, and a fourth portion disposed in contact with the another surface of the insulating layer, the second portion blocking an entirety of the first end of the through-hole such that a surface of the second portion does not intrude into the through-hole, the third portion partially blocking the second end of the through-hole such that a surface of the third portion intrudes into the through-hole to extend along the inner circumferential surface of the through-hole.