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AssigneeMatsushita Electric Works, Ltd.
InventorsHirokazu Yoshioka, Norio Yoshida, Kenichiro Tanaka
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A multilayer printed wiring board is formed with a plurality of conductor layers laminated as a whole with insulating layers interposed, a non-penetrating via hole provided in the insulating layer as bottomed by the conductor layer exposed, a plated layer provided inside the via hole for electric connection between the conductor layers, the via hole being formed to be of a concave curved surface of a radius in a range of 20 to 100 μm in axially sectioned view at continuing zone of inner periphery to bottom surface of the via hole, whereby the equipotential surfaces occurring upon plating the plated layer are curved along the continuing zone to unify the density of current for rendering the plated layer uniform in the thickness without being thinned at the continuing zone.
A method for manufacturing a multilayer printed wiring board in which a plurality of conductor layers are laminated as a whole with insulating layers interposed, comprising the steps of irradiating the insulating layers with a carbon dioxide gas laser having a pulse width in a range of 1 to 100 μs to form a non-penetrating via hole in the insulating layer as bottomed by each conductor layer exposed so as to have, at least at a continuing zone of the inner periphery to the bottom surface, a concave curved surface of a radius of more than 20 μm in an axially sectioned view of the via hole, forming a plated conductor layer inside the via hole for electric connection between the conductor layers, preparing an inner layering substrate having a wiring pattern forming the conductor layer bottoming the via hole, adhering through the insulating layer a thermosetting resin onto the inner layering substrate a metal foil forming another conductor layer to be electrically connected to the wiring pattern through the plated layer, etching the metal foil to remove a portion thereof where the via hole is to be provided, irradiating the carbon dioxide gas laser of a beam larger in the diameter than a diameter of the portion where the foil is etched off to remove the insulating layer at the portion to thus form the via hole, and providing the plated layer with an electrically conducting substance through a plating for electrically connecting the wiring pattern and the metal foil.
A method for manufacturing a multilayer printed wiring board in which a plurality of conductor layers are laminated as a whole with insulating layers interposed therebetween, comprising the steps of irradiating the insulating layers with a carbon dioxide gas laser having a pulse width in a range of 1 to 100 μs to form a non-penetrating via hole in the insulating layer as bottomed by each conductor layer exposed so as to have, at least at a continuing zone of the inner periphery to the bottom surface, a concave curved surface of a radius of more than 20 μm in an axially sectioned view of the via hole, forming a plated conductor layer inside the via hole for electric connection between the conductor layers, and applying a permanganic acid solution for removing any remaining insulating substance on the bottoming conductor layer in the via hole.
A method for manufacturing a multilayer printed wiring board in which a plurality of conductor layers are laminated as a whole with insulating layers interposed, comprising the steps of forming a non-penetrating via hole by means of irradiation by a laser in the respective insulating layers from an opening made in one of the conductor layers on one surface of the insulating layer to a surface of another conductor layer on the other surface of the insulating layer, and forming a plated conductor layer on the inner periphery of the via hole for electric connection between the conductor layers on both surfaces of the respective insulating layer, including forming the via hole in the insulating layer, so as to have, at least at a continuing zone or the inner periphery to tie bottom surface, a concave curved surface of a radius of more than 20 μm in an axially sectioned view of the via hole.
Dependencies are inferred from the claim text.