JP-7856217-B2 - Wiring board, electronic module, and method for manufacturing a wiring board

JP7856217B2JP 7856217 B2JP7856217 B2JP 7856217B2JP-7856217-B2

Inventors

上田英樹
池本伸郎
古村知大
南谷直貴

Assignees

株式会社村田製作所

Dates

Publication Date: 20260511
Application Date: 20240208
Priority Date: 20230501

Claims (13)

A first insulating film having through holes that penetrate in the thickness direction, A first conductor pattern is arranged on the first surface, which is one of the surfaces of the first insulating film, and closes the opening of the through hole on the first surface side, The first connecting conductor is disposed within the through-hole and connected to the first conductor pattern, and its dimension in the thickness direction is smaller than the dimension in the thickness direction of the first insulating film, A wiring board in which the metal element with the highest content in the first conductor pattern and the metal element with the highest content in the first connecting conductor are the same.
Furthermore, it is equipped with a base substrate, The wiring board according to claim 1, wherein the first insulating film is disposed on the base substrate with its first surface facing the base substrate, and the first conductor pattern is disposed between the first insulating film and the base substrate.
The base substrate includes a plurality of second conductor patterns, a plurality of second insulating films, and a plurality of second connecting conductors. The wiring substrate according to claim 2, wherein the first insulating film is disposed on the surface of the uppermost of the plurality of second insulating films.
The wiring board according to claim 3, wherein the metal element with the highest content in each of the plurality of second conductor patterns and the metal element with the highest content in each of the plurality of second connecting conductors are the same.
The wiring board according to claim 3, wherein each of the plurality of second connecting conductors is formed from a conductive material formed from a hardened conductive paste, and each of the plurality of second conductor patterns is formed from a conductive material different from the plurality of second connecting conductors.
Each of the plurality of second connecting conductors includes a first portion that contacts the plurality of second conductor patterns and a second portion that contacts the second conductor pattern closer to the first insulating film, wherein the metal element with the highest content in the first portion is the same as the metal element with the highest content in the second conductor pattern that the first portion contacts, and the second portion is formed of a conductive material formed from a hardened conductive paste, as described in claim 3.
The wiring board according to any one of claims 1 to 6, wherein the upper surface of the first connecting conductor has a concave shape, with the center being lower than the outer periphery.
The wiring board according to any one of claims 1 to 6, wherein the upper surface of the first connecting conductor has a convex shape, with the center being higher than the outer periphery.
The wiring board according to any one of claims 1 to 6 , wherein the through-hole has a shape that widens in a direction away from the first conductor pattern.
The wiring board according to any one of claims 1 to 6, wherein the first connecting conductor and the first conductor pattern are formed of copper, silver, gold, an alloy mainly composed of copper, an alloy mainly composed of silver , or an alloy mainly composed of gold.
The wiring board according to any one of claims 1 to 6 , further comprising a surface treatment layer on the surface of the first connecting conductor, comprising at least one material selected from the group consisting of Ni, Au, solder, and flux.
A wiring board according to any one of claims 1 to 6 , The circuit board comprises electronic components mounted via solder bumps, The solder bump is connected to the electronic module on the first connecting conductor.
A first insulating film is prepared, on which a first conductive pattern is formed on one of its surfaces, the first surface. A through hole is formed in the first insulating film, extending from the surface opposite to the first surface to the first conductor pattern. A method for manufacturing a wiring board in which a first connecting conductor is formed in the through-hole by a plating method, using the first conductor pattern as a seed, The metal element with the highest content in the first conductor pattern and the metal element with the highest content in the first connecting conductor are the same. A method for manufacturing a wiring board in which the thickness dimension of the first connecting conductor is smaller than the thickness dimension of the first insulating film on the first conductor pattern.

Description

This invention relates to a wiring board, an electronic module, and a method for manufacturing a wiring board. Various wiring boards for mounting electronic components are known (Patent Documents 1, 2, and 3). The wiring boards disclosed in Patent Documents 1 and 2 include an inner layer conductor pattern on the substrate and a double layer (insulating layer) covering the inner layer conductor pattern. An opening is provided in the double layer, and a part of the surface of the inner layer conductor pattern is exposed at the bottom of the opening. The surface of the inner layer conductor pattern exposed within the opening is covered with a surface treatment layer (surface layer). The portion of the inner layer conductor pattern exposed within the opening is used as a terminal for mounting electronic components. The surface treatment layer functions as a connecting conductor for connecting solder bumps, etc., of electronic components to the inner layer conductor pattern. In Patent Document 1, copper foil is used for the inner layer conductor pattern, and solder, alloys, gold, silver, nickel, etc., are used for the surface treatment. In Patent Document 2, a metal mainly composed of copper is used for the inner layer conductor pattern, and Ni-Au plating or Sn (solder) plating is used for the surface layer. The surface layer protects the inner layer conductor pattern below it. In the wiring board disclosed in Patent Document 3, connecting conductors are filled into through-holes facing the first resin layer. The connecting conductors are connected to the inner layer conductor pattern of the lower layer. A second resin layer is placed on top of the first resin layer, and the second resin layer is provided with openings that expose the connecting conductors. The connecting conductors exposed in the openings are used as terminals for mounting electronic components. A melting point-changing bonding material is used for the connecting conductors. Japanese Patent Publication No. 2005-235981Japanese Patent Publication No. 2005-244108International Publication No. 2015/170539 Figure 1 is a cross-sectional view of a wiring board according to the first embodiment.Figures 2A and 2B are cross-sectional views of the wiring board during the manufacturing process according to the first embodiment.Figure 3 is a cross-sectional view of a wiring board according to the second embodiment.Figure 4 is a cross-sectional view of a wiring board illustrating the excellent effects of the second embodiment.Figure 5 is a cross-sectional view of an electronic module according to the third embodiment.Figure 6 is a cross-sectional view of a wiring board according to the fourth embodiment.Figure 7 is a cross-sectional view of a wiring board according to a modified example of the fourth embodiment.Figure 8 is a cross-sectional view of a wiring board according to another modification of the fourth embodiment.Figure 9 is a cross-sectional view of a wiring board according to yet another modification of the fourth embodiment.Figure 10 is a cross-sectional view of a wiring board according to the fifth embodiment.Figure 11 is a cross-sectional view of a wiring board according to a modified example of the fifth embodiment. [First Embodiment] A wiring board according to the first embodiment will be described with reference to the drawings from Figure 1 to Figure 2B. Figure 1 is a cross-sectional view of a wiring board 50 according to the first embodiment. The wiring board 50 according to the first embodiment includes a first insulating film 21 with through holes 21A formed therein, a first conductor pattern 20, a first connecting conductor 22 disposed within the through holes 21A, and a surface treatment layer 23 disposed on the surface of the first connecting conductor 22. For example, multiple through holes 21A are provided, but Figure 1 shows one through hole 21A. The first conductor pattern 20 is arranged on the first surface 21B, which is one surface of the first insulating film 21. The first conductor pattern 20 closes the opening of the through hole 21A on the side of the first surface 21B. Hereinafter, the surface of various components facing in the opposite direction from the first surface 21B will be referred to as the top surface. Also, the direction perpendicular to the first surface 21B may be referred to as the thickness direction. The side surface of the through-hole 21A is inclined such that the area of the planar cross-section (cross-section parallel to the first surface 21B) of the through-hole 21A increases as it moves away from the first conductor pattern 20 upwards. In other words, the through-hole 21A has an inverse tapered shape that narrows downwards. When the first insulating film 21 is viewed from above (hereinafter sometimes simply referred to as "in a planar view"), the through-hole 21A is contained within the first conductor pattern 20. The first connecting conductor 22, positioned within the through-hole 21A, is in contact