Method of manufacturing multilayer printed wiring board
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorMasashi Tachibana
Life of this patent
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Abstract
Photosensitive resin is applied to an internal conductive pattern layer (2) as well as to an inside layer which has a hole (3a) filled with conductive paste (3b). A hole (4a) communicating to the internal conductive pattern layer (2) by exposure and development is formed. Then, metal plated film (6a) is formed on the surface of the photosensitive resin (4) including the hole (4a). Metal plated film (6a) is processed into an external conductive pattern layer (6a). This manufacturing method can increase the wiring density on the external conductive pattern layer (6), and thus a multilayer printed wiring board of increased wiring density can be obtained.
Claims1
A method of manufacturing a multilayer printed wiring board, comprising:
- forming a through hole in an aramid nonwoven fabric impregnated with a thermosetting resin when the impregnating thermosetting resin is in a semi-setting state;
- filling the through hole with conductive paste to complete an insulating substrate;
- bonding a copper foil on both sides of the insulating substrate by thermo-compression to form a copper-clad laminate;
- forming an internal conductive pattern layer and an internal conductive pattern land made of only the copper foil to complete an inner circuit board, said land covering a portion of said aramid nonwoven fabric where the through hole is formed;
- forming a photosensitive resin film on a surface of the inner circuit board;
- forming a photo via communicating with the land or the internal conductive pattern layer in the applied photosensitive resin film by exposing and developing said film;
- filling the photo via with conductive paste, the viscosity of which is adjusted by adding solvent;
- reducing the solvent from the conductive paste filled in the photo via;
- and
- forming an external conductive pattern layer on the photosensitive resin film and a land just above the photo via by plating on a surface of the photosensitive resin film said surface including a portion lust above the photo via,
- wherein a diameter of the photo via is smaller than the diameter of the through hole, and a diameter of the land on the photo via is smaller than a diameter of the internal conductive pattern land.
Dependencies are inferred from the claim text.