A first stack is formed by stacking a first sheet of metal foil, a first prepreg, and a second sheet of metal foil, one on top of another. The first prepreg is thermally cured by thermally pressing these members to make a double-sided metal-clad laminate. Conductor wiring is formed by partially removing the first sheet of metal foil from the double-sided metal-clad laminate to make a printed wiring board. After a third sheet of metal foil has been preheated, the conductor wiring of the printed wiring board, a second prepreg, and the third sheet of metal foil are stacked one on top of another and thermally pressed together. The first insulating layer has a lower linear expansion coefficient than any of the first sheet of metal foil or the second sheet of metal foil does.

A reel-to-reel machine to fabricate a printed flexible circuit on the fly, the machine has a plurality of reels, a laser scanner to ablate a metal foil, a source of UV light or heat to curing an adhesive in a coverlay, another source of UV light or heat to debond a sacrificial liner on the fly. There is a depositor to deposit a sintering paste on the fly onto a predetermined spot for a pad on the metal foil. Removal of slugs are also possible on the fly.

A reel-to-reel method of creating pads on a layer of metal sheet or circuitry pattern on the fly. The method includes placing a sintering paste in the intended spots for pads followed by irradiation of the sintering paste by a laser.

A method of making a printed circuit board structure including a closed cavity is provided. The method can include the steps of forming a cavity in a core structure of a core layer, laminating each of a top surface and a bottom surface of the core structure with an adhesive layer and a metal layer to prepare a laminate structure and cover the cavity to define a closed cavity. The method also includes forming vias through the laminate structure, and patterning the metal layers in the laminate structure.

A method for making an ultra-thin dielectric printed circuit board (PCB) is provided. A first side of a first conductive layer is removably coupled to a disposable base. A first ultra-thin dielectric layer and a second conductive layer are laminated to a second side of the first conductive layer, where the first ultra-thin dielectric layer is positioned between the first and second conductive layers, and the first ultra-thin dielectric layer is thinner than at least one of the first conductive layer and the second conductive layer. The second conductive layer may then be patterned to form electrical paths. The patterned second conductive layer is then filled with a dielectric filler. One or more conductive layers and one or more ultra-thin dielectric layers may then be coupled to the second conductive layer. The disposable base may then be detached from the first conductive layer.

A method of layering a layer of circuitry pattern to another layer of circuitry pattern during the manufacturing of a multilayer flexible printed circuit in a reel-to-reel machine. The method includes feeding both layers of circuitry pattern reel-to-reel into the machine, placing a layer of dielectric sheet material on the fly between the two layers of circuitry patterns reel-to-reel, followed by simultaneously passing the two layers of circuitry pattern and the dielectric sheet material under a laser scanner in the reel-to-reel machine to irradiate a laser beam on a layer of circuitry pattern to weld the two layers of circuitry patterns together.

A method of making a printed circuit board includes a step of providing a double-sided plate that is an insulating substrate having conductive layers on respective surfaces thereof, a first coating step of coating a first surface of the double-sided plate with a first photosensitive resin film, a second coating step of coating a second surface of the double-sided plate with a second photosensitive resin film, a first exposure step of exposing the photosensitive resin film coating the first surface after the first and second coating steps, and a second exposure step of exposing the photosensitive resin film coating the second surface after the first exposure step, wherein a maximum depth of a depression in an outermost surface of the second photosensitive resin film used in the second exposure step is less than 1.0 m.

A method of manufacturing a constituent for a component carrier is disclosed. The method includes providing an electrically conductive structure, forming a highly thermally conductive and electrically insulating or semiconductive structure on the electrically conductive structure, and subsequently, attaching a thermally conductive and electrically insulating structure, having a lower thermal conductivity than the highly thermally conductive and electrically insulating or semiconductive structure, on an exposed surface of the highly thermally conductive and electrically insulating or semiconductive structure.

The present invention provides a surface treated copper foil in which a dropping of the roughening particles from a roughening treatment layer on the surface of the copper foil is suppressed and an occurrence of wrinkles or stripes when bonding with an insulating substrate is suppressed. The surface of the roughening treatment layer satisfies one or more of the following: a roughness Ra is 0.08 to 0.20 m, a roughness Rz is 1.00 to 2.00 m, a roughness Sq is 0.16 to 0.30 m, a roughness Ssk is 0.6 to 0.35, a roughness Sa is 0.12 to 0.23 m, a roughness Sz is 2.20 to 3.50 m, a roughness Sku is 3.75 to 4.50, and a roughness Spk is 0.13 to 0.27 m, a glossiness of a TD of the surface of the side of the roughening treatment layer of the surface treated copper foil is 70% or less.

The present invention provides a multilayer circuit board and a method for manufacturing the same for improving a bowing problem that occurs when manufacturing the multilayer circuit board. A multilayer circuit board according to the present invention is a board having a patterned layer that functions as a circuit a base layer, and includes: a second pattern layer formed on one side of the base layer; a first pattern layer formed on the second pattern layer; and an interlayer insulating layer formed between the first pattern layer and the second pattern layer, the interlayer insulating layer being partially formed on the second pattern layer so as to correspond to a region where the first pattern layer is formed.