A printed circuit board according to an embodiment comprises: an insulating layer; a circuit pattern disposed on the upper surface of the insulating layer; a support layer which is disposed on the upper surface of the insulating layer to expose the upper surface of the circuit pattern and is in contact with the sides of the circuit pattern; and a protective layer disposed on the upper surfaces of the support layer and the circuit pattern, wherein the upper region of the insulating layer comprises a first region and a second region, and the protective layer comprises an open region exposing the upper surfaces of the support layer and the circuit pattern that are disposed in the first region, and the support layer comprises a first upper surface positioned at the highest level among the upper surfaces of the support layer and a second upper surface positioned at the lowest level among the upper surfaces of the support layer, the second upper surface being lower than the first upper surface, and the protective layer comprises a first portion which contacts the upper surface of the circuit pattern of the first region and a second portion which contacts the upper surface of the support layer of the first region, and the second portion of the protective layer contacts the second upper surface of the support layer and includes a first lower surface which is lower than the upper surface of the circuit pattern.

A wiring substrate includes a core substrate, a first wiring structure located on an upper surface of the core substrate, and a second wiring structure located on an upper surface of the first wiring structure. The first wiring structure includes a structure in which one or more first wiring layers and one or more first insulating layers are stacked. The second wiring structure includes a structure in which multiple second wiring layers and multiple second insulating layers are stacked. The second wiring structure has a higher wiring density than the first wiring structure. The second insulating layer has a thermal expansion coefficient higher than that of the core substrate and lower than that of the first insulating layer.

A circuit board structure includes a flexible core board, a first circuit layer, a first solder mask layer, a first protective layer, a rigid plate and a plurality of electrically-conductive members. The flexible core board includes a first surface and a second surface. The first circuit layer is formed on the first surface, and has a plurality of electrical connection portions. The first solder mask layer is coated on the first circuit layer and the first surface. The first solder mask layer has a plurality of opening portions aligned with the electrical connection portions. The first protective layer is disposed on the first solder resist layer and has a flat surface. The rigid plate is disposed on the second surface and corresponds to the opening portions. The electrically-conductive members are respectively formed on the electrical connection portion and exposed from the opening portion.

A printed wiring board includes a base film having a first major surface provided with a groove, and a wiring line disposed in the groove. The wiring line includes a metal particle layer disposed at least on a bottom surface of the groove and a plating layer disposed on the metal particle layer. The metal particle layer contains a plurality of metal particles bonded to each other by metallic bonding. A surface of each of the plurality of metal particles is partially coated with an organic film.

A printed circuit board includes an insulating layer, a conductive pad disposed on the insulating layer, a conductive bump disposed to cover at least a portion of the conductive pad and spaced apart from the insulating layer, and a solder resist layer disposed on the insulating layer and covering at least a portion of both the conductive pad and the conductive bump. The conductive bump has a maximum width greater than that of the conductive pad. A method of manufacturing the printed circuit board is also disclosed.