Printed wiring board

Patent metadata

Field	Value
Publication number	US-12538432-B2
Application number	US-202218681035-A
Country	US
Kind code	B2
Filing date	May 26, 2022
Priority date	Aug 6, 2021
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

A printed wiring board includes a base film having a first major surface provided with a groove, and a wiring line disposed in the groove. The wiring line includes a metal particle layer disposed at least on a bottom surface of the groove and a plating layer disposed on the metal particle layer. The metal particle layer contains a plurality of metal particles bonded to each other by metallic bonding. A surface of each of the plurality of metal particles is partially coated with an organic film.

First claim

The invention claimed is:

1 . A printed wiring board comprising:
a base film having a first major surface provided with a groove; and a wiring line disposed in the groove, wherein the wiring line includes a metal particle layer disposed at least on a bottom surface of the groove and a plating layer disposed on the metal particle layer, wherein the metal particle layer contains a plurality of metal particles bonded to each other by metallic bonding, and wherein a surface of each of the plurality of metal particles is partially coated with an organic film.

2 . The printed wiring board according to claim 1 ,
wherein the metal particle layer is disposed on the bottom surface of the groove and a side surface of the groove.

3 . The printed wiring board according to claim 1 ,
wherein the plurality of metal particles are made of copper.

4 . The printed wiring board according to claim 1 ,
wherein the plurality of metal particles are made of silver.

5 . The printed wiring board according to claim 1 ,
wherein the organic film is made of a polymeric material having a number-average molecular weight of 100 to 1000000.

6 . The printed wiring board according to claim 1 ,
wherein a d50 of the plurality of metal particles is 1 nm to 500 nm.

7 . The printed wiring board according to claim 1 ,
wherein the plating layer includes an electroless plating layer disposed on the metal particle layer and an electrolytic plating layer disposed on the electroless plating layer.

8 . The printed wiring board according to claim 1 ,
wherein the plating layer includes an electrolytic plating layer disposed on the metal particle layer.

9 . The printed wiring board according to claim 1 ,
wherein the wiring line includes a portion where a value obtained by dividing a height of the wiring line by a width of the wiring line is 2 or more.

10 . The printed wiring board according to claim 1 ,
wherein the groove includes a first groove portion and a second groove portion adjacent to each other with a space between the first groove portion and the second groove portion, wherein the wiring line includes a first portion disposed in the first groove portion and a second portion disposed in the second groove portion, and wherein the wiring line includes a portion where a value obtained by dividing a height of the wiring line by the space between the first portion and the second portion is 2 or more.

11 . The printed wiring board according to claim 1 ,
wherein the base film is made of a polyimide.

12 . The printed wiring board according to claim 1 ,
wherein the base film further has a second major surface, the second major surface being a surface opposite to the first major surface, and wherein a width of the groove decreases in a direction from the first major surface toward the second major surface.

13 . The printed wiring board according to claim 1 , further comprising:
an adhesive covering the first major surface, the adhesive being provided in the groove to cover the wiring line; and a coverlay attached to the first major surface with the adhesive.

14 . The printed wiring board according to claim 1 , further comprising:
a solder resist covering the first major surface, the solder resist being provided in the groove to cover the wiring line.

Assignees

• Sumitomo Electric Industries
• Sumitomo Electric Printed Circuits Inc

Inventors

• Yamamoto Masamichi
• Hashizume Kayo
• Okada Issei
• Aikawa Kenichiro
• Oka Yoshio

Classifications

• H05K2201/2081

  Compound repelling a metal, e.g. solder · CPC title

• H05K2201/0154

  Polyimide · CPC title

• H05K3/188

  by direct electroplating · CPC title

• H05K3/181

  by electroless plating (adhesives therefor H05K3/387) · CPC title

• H05K1/09

  Use of materials for the {conductive, e.g. } metallic pattern · CPC title