An extremely thin copper foil is provided that enables formation of highly fine different wiring patterns with a line/space (L/S) of 10 μm or less/10 μm or less on two sides of the copper foil and is thus usable as an inexpensive and readily processable substitution for silicon and glass interposers. The extremely thin copper foil includes, in sequence, a first extremely thin copper layer, an etching stopper layer, and the second extremely thin copper layer. Two sides of the extremely thin copper foil each have an arithmetic average roughness Ra of 20 nm or less.

A method of manufacturing a printed circuit board a includes preparing an insulating substrate on which a first metal layer is formed, stacking a resist laminate having a plurality of layers on the first metal layer, forming an opening exposing a portion of the first metal layer by patterning the stacked resist laminate having the plurality of layers, forming a second metal layer on the exposed portion of the first metal layer, removing the patterned resist laminate having the plurality of layers, and etching at least another portion of the first metal layer.

Methods and composition sets for forming etch-resist masks on a metallic surface are provided. The method may include depositing a first aqueous composition comprising a first reactive component onto a metallic layer of a substrate; depositing a second aqueous composition comprising a second reactive component on selected portions of the deposited first aqueous composition to form, from a chemical reaction between the first reactive component and the second reactive component, a bi-component material mask in a pattern to protect selected regions of the metallic layer; and depositing an etch solution to remove the metallic layer in regions not protected by the bi-component material mask.

Methods and composition sets for forming etch-resist masks on a metallic surface are provided. The method may include depositing a first aqueous composition comprising a first reactive component onto a metallic layer of a substrate; depositing a second aqueous composition comprising a second reactive component on selected portions of the deposited first aqueous composition to form, from a chemical reaction between the first reactive component and the second reactive component, a bi-component material mask in a pattern to protect selected regions of the metallic layer; and depositing an etch solution to remove the metallic layer in regions not protected by the bi-component material mask.

The present disclosure relates to a printed circuit board and a method of manufacturing the same. The printed circuit board includes: an insulating layer; a plurality of pads disposed on the insulating layer; and a plurality of insulating walls that are disposed on the insulating layer and cover side surfaces of the plurality of pads, respectively, but are not disposed on upper surfaces of the plurality of pads. The plurality of insulating walls are disposed to be spaced apart from each other on the first insulating layer.

The present invention is related to a composition for micro etching of a copper or a copper alloy surface, wherein the composition comprises i) at least a source of Fe.sup.3+ ions, ii) at least a source of Br.sup.− ions, iii) at least an inorganic acid, and iv) at least one etch refiner according to formula I

##STR00001## wherein R1 is selected from the group consisting of hydrogen, C.sub.1-C.sub.5-alkyl or a substituted aryl or alkaryl group; R2 is selected from the group consisting of hydrogen, C.sub.1-C.sub.5-alkyl or C.sub.1-C.sub.5-alkoxy; R3, R4 are selected from the group consisting of hydrogen and C.sub.1-C.sub.5-alkyl; and X.sup.− is a suitable anion. Further, the present invention is directed to a method for micro etching of copper or copper alloy surfaces using such a composition.

[Problem to be Solved]

A multilayer flexible printed circuit board having a strip line advantageous to folding is provided.

[Solution]

A multilayer flexible printed circuit board 100 of an embodiment is a multilayer flexible printed circuit board having a strip line foldable at a folding part F1, the board including: a flexible insulative substrate 30; an inner layer circuit pattern 5 provided inside the flexible insulative substrate 30 and including a signal line 6 extending in a predetermined direction; a ground thin film 14a constituting a ground layer at least in the folding part F1 out of a ground layer of the strip line and constituted of a nonelectrolytic plating coat 14 formed on the flexible insulative substrate 30; and a protective layer 20 that covers the ground thin film 14a and is in close contact with an exposed part 19 from which the flexible insulative substrate 30 is exposed.

One embodiment of the present disclosure provides a method for producing a substrate formed with a copper thin layer. The method includes providing a carrier, forming a separation-inducing layer on the surface of the carrier, forming a copper thin layer on the separation-inducing layer, and bonding a core to the copper thin layer.

A method is described for method for patterning a metal layer interfaced with a transparent conductive film, in which the method comprises contacting a structure through a patterned mask with an etching solution comprising Fe.sup.+3 ions, wherein the structure comprises the metal layer comprising copper, nickel, aluminum or alloys thereof covering at least partially a transparent conductive film with conductive elements comprising silver, to expose a portion of the transparent conductive film. Etching solutions and the etched structures are also described.

A method for manufacturing a printed wiring board includes forming metal posts on a conductor circuit formed on a resin insulating layer, forming the outermost resin layer on the resin insulating layer such that the metal posts is embedded in the outermost resin layer, forming a mask at a dam formation site for a dam structure of the outermost resin layer to surround at least part of a pad group including the metal posts on the outermost resin layer, and reducing a thickness of the outermost resin layer exposed from the mask such that end portions of the metal posts are exposed from the outermost resin layer, that the metal posts form the pad group, and that the outermost resin layer has the dam structure forming part of the outermost resin layer and formed to surround at least part of the pad group including the metal posts.