Method for manufacturing printed wiring board and copper foil for laser processing

Abstract

An object of the present invention is to provide a method of producing a printed wiring board which reduces production steps, is excellent in infrared laser processability, and is suitable for formation of an excellent wiring pattern; and to provide a copper foil for laser processing and a copper-clad laminate. In order to achieve the object, a method of producing a printed wiring board comprises: forming a via-hole for interlayer connection in a laminate in which a copper foil for laser processing comprises a copper foil and an easily soluble laser absorption layer provided on a surface of the copper foil which has a higher etching rate to a copper etchant than the copper foil and absorbs an infrared laser beam and another conductor layer is laminated through an insulating layer, directly irradiating the infrared laser beam on the easily soluble laser absorption layer; and removing the easily soluble laser absorption layer from the surface of the copper foil in a desmear step of removing a smear in a via-hole and / or a microetching step as a pretreatment of an electroless plating step is adopted.

Description

technical field [0001] The present invention relates to a method of manufacturing a printed wiring board and a copper foil for laser processing, and in particular to a method of manufacturing a printed wiring board capable of forming via holes for interlayer connection by a Cu direct method, and a copper foil for laser processing. Background technique [0002] The multilayering of printed wiring boards has been progressing along with the function enhancement and compactness of electronic instruments and electrical equipment. A multilayer printed wiring board is a printed wiring board in which three or more wiring layers are laminated with an insulating layer sandwiched between them, and the wiring layers are electrically connected by interlayer connection means such as via holes or through holes. A build-up method is known as a method for manufacturing a multilayer printed wiring board. The so-called build-up method refers to a manufacturing method in which wiring layers ar...

AI Technical Summary

Problems solved by technology

However, copper has an extremely low absorption rate of laser light in the far-infrared to infrared wavelength range, such as carbon dioxide lasers. Therefore, when forming microvias by the Cu direct method, it is necessary to perform blackening treatment in advance to improve the surface of the copper foil. Absorptivity Pretreatment

[0004] However, when the surface of the copper foil is blackened, the surface of the copper foil will be etched, so the thickness of the copper foil will decrease, and at the same time, variations will occur in the thickness

Therefore, when removing the seed layer, it is necessary to set the etching time according to the thickest part of the seed layer, which leads to a problem that it is difficult to form a wiring pattern with high linearity and good line width.