JPH09331145A - Wiring board pad structure - Google Patents

Abstract

(57) Abstract: In a wiring board in which laminated photosensitive resins are exposed to form vias for connection with internal wiring, even when the vias are formed at the component mounting pad positions on the surface layer, To enable reliable component mounting without solder connection failure. Internal wiring 2 is formed on a substrate 1. A photosensitive resin layer 3 is formed on the internal wiring 2, and a via 4 is formed in a part thereof. A conductive material layer 5 for interlayer connection made of a metal having excellent conductivity is formed on the inner surface of the via 4 and in the vicinity of the upper surface of the photosensitive resin layer 3. Filling layer 6 made of resin
Is filled. At other places on the upper surface of the photosensitive resin layer 3, a flat layer 7 made of a photosensitive resin is formed so as to be flat in conformity with the upper surface of the conductive material layer 5 for interlayer connection. Component mounting pads 8 are formed on the upper surfaces of the interlayer-connecting conductive material layer 5 and the filling layer 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pad structure of a printed wiring board in which a photosensitive resin is laminated and connection vias between layers are formed by exposure.

[0002]

2. Description of the Related Art In recent years, the performance and miniaturization of electronic devices have advanced, and it has become necessary to route a large number of signal wirings on a printed wiring board with a minimum area. Conventionally, this type of printed wiring board has dealt with an increase in the number of signal lines by forming a multilayer structure. In general, the connection between the layers is described in “Nikkei Electronics No. 633” (1995).
As shown in FIG. 2A, a hole (through hole) penetrating the entire multilayer substrate is used.

[0003] However, the diameter of this through hole is as large as about 300 µm because a hole is formed by a drill, and this has an effect on a wiring space when many wires are to be routed. Therefore, in order to be able to route more wiring, "Nikkei Electronics No. 633"
(Published April 10, 1995) Page 101 As shown in FIG. 2C, a wiring board is used in which a photosensitive resin is laminated and a hole (via) for connection between layers is formed by exposure. It has become In this method, a via diameter is set to 100 because a via is formed by exposing a photosensitive resin.
１５０150 μm. Therefore, more wiring can be drawn out as compared with a conventional printed wiring board of the same size.

As such a wiring board, there is one as shown in FIG. FIG. 27 is a partial sectional view of the outermost layer portion of the wiring board. In this figure, an internal wiring 42 is formed on the upper surface of a substrate 41, and a photosensitive resin layer 43 is further applied on the internal wiring 42. Vias 44 are formed in the photosensitive resin layer 43 by light exposure.
The conductive material plated on the photosensitive resin layer 43 serves as a component mounting pad 45. The conductive material plated on the photosensitive resin layer 43 serves as a component mounting pad. The component mounting pad 45 is formed by removing an unnecessary portion of the surface plating by etching.

By the way, in a printed wiring board, generally, a component mounting pad 47 is drawn at a position away from a through hole 46 as shown in FIG. Also,
Also in the case of a wiring board in which a photosensitive resin is laminated to form a via by exposure, component mounting pads are formed in the same arrangement. However, in the case of a wiring board in which a via is formed by exposing the laminated photosensitive resin, the diameter of the via is 100 to 150.
Since it is as small as μm, it is possible to form the via 44 inside the component mounting pad 45 as shown in FIG. 29, and it is effective when there is no space in which to route the wiring.

[0006]

However, in the above-described conventional wiring board, when a via is formed at a component mounting pad position on the surface layer, a recess of the via is formed on the component mounting pad. There is a problem that a connection failure may occur. That is, when component mounting is performed using a solder paste, molten solder may be caught in the concave portion and a connection failure may occur.Also, when solder is coated on component mounting pads in advance before component mounting, soldering may occur. Is formed in the concave portion of the via, so that a thin portion is formed in the solder-coated portion, and the solder surface is extremely oxidized, which may cause a connection failure at the time of subsequent component mounting.

Japanese Patent Laid-Open No. Hei 4-11689 discloses a method of eliminating a concave portion of a through-hole penetrating vertically above and below a wiring board.
As shown in Japanese Patent Publication No. 1 (1993), there is a method in which plating is deposited on the upper and lower ends of a through hole filled with a conductive metal to fill the through hole and flatten it. It is difficult to deposit and flatten the top of the through hole. Further, in the case of deposition by plating, since the plating metal is formed so as to follow the conductive metal as the base, it is difficult to deposit until the concave portion is completely filled, which is costly and time consuming.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-described problem, and is directed to a wiring board for exposing a laminated photosensitive resin to form a via for connection with an internal wiring, and a position of a component mounting pad located on a surface layer. Even if a via is formed in
An object of the present invention is to provide a pad structure of a wiring board that can perform reliable component mounting without solder connection failure.

[0009]

In order to achieve the above object, a pad structure of a wiring board of the present invention has a substrate, an internal wiring formed on the substrate, and a photosensitive layer formed on the substrate and the internal wiring. A resin layer, a via formed in the photosensitive resin layer to expose the internal wiring, a conductive material layer for interlayer connection formed in the via and the photosensitive resin layer, and a filling filled inside the conductive material layer for interlayer connection And a component mounting pad formed on the filling layer and the conductive material layer for interlayer connection. Preferably, the filling layer is formed of a conductive resin.

Further, the pad structure of the wiring board of the present invention comprises:
The substrate, the internal wiring formed on the substrate, the photosensitive resin layer formed on the substrate and the internal wiring, the via formed in the photosensitive resin layer to expose the internal wiring, the via and the photosensitive resin layer It has a formed conductive material layer for interlayer connection and a solder resist formed around the recess of the conductive material layer for interlayer connection, and the portion of the conductive material layer for interlayer connection on the photosensitive resin layer is for mounting components. It is configured as a pad. Further, preferably, the component mounting pad is subdivided by a solder resist.

According to the pad structure of the wiring board of the present invention having the above structure, the filling layer is filled in the concave portion of the via existing in the component mounting pad, so that the solder does not enter the concave portion. The solder resist formed around the via prevents the solder from entering the recess of the via.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the pad structure of a wiring board according to the present invention will be described with reference to FIGS. FIG.
2 is a sectional view of a pad structure of a wiring board, and FIGS. 2 to 10 are sectional views of a manufacturing process of the pad structure of the wiring board. In FIG. 1, reference numeral 1 denotes a substrate made of a photosensitive resin, on which an internal wiring 2 is formed. A photosensitive resin layer 3 is formed on the internal wiring 2, and a via 4 is formed in a part thereof. In the inner surface of the via 4 and in the vicinity of the upper surface of the photosensitive resin layer 3, a conductive material layer 5 for interlayer connection made of a metal having excellent conductivity such as copper, silver, and gold is formed. A filling layer 6 made of a photosensitive resin is provided inside the material layer 5.
Is filled. In other places on the upper surface of the photosensitive resin layer 3, a flat layer 7 made of a photosensitive resin is formed so as to be flat with the upper surface of the conductive material layer 5 for interlayer connection. 7, component mounting pads 8 are formed on the upper surfaces of the conductive material layer 5 for interlayer connection and the filling layer 6.

Next, the manufacturing method will be described. First,
As shown in FIG. 2, the internal wiring 3 is formed on the surface substrate 1 using a conductive material. As a method of forming the internal wiring 3, a method of plating a metal having excellent conductivity such as copper, silver, or gold, attaching these metal foils, and leaving only a necessary portion of the internal wiring 3 chemically or There is a method of removing unnecessary portions by mechanical polishing.

Next, as shown in FIG. 3, a photosensitive resin layer 3 is formed by applying a photosensitive resin over the internal wiring 3 to a predetermined thickness, and then, as shown in FIG. Is exposed and developed to form a via 4 serving as a base for drawing out the internal wiring 3 to the surface.

Next, as shown in FIG. 5, a conductive material such as copper or silver gold is plated from the surface to form a conductive material layer 5 for interlayer connection, and as shown in FIG. Etching is removed while leaving only necessary portions of the conductive material 5 for interlayer connection. Then, as shown in FIG. 7, a photosensitive resin is applied from above, exposed and developed to form a resin layer, and thereafter,
As shown in FIG. 8, the cured photosensitive resin on the surface is polished and flattened until the conductive material layer 5 for interlayer connection is exposed, so that the filling layer 6 and the flat layer 7 are formed.

Next, as shown in FIG. 9, the photosensitive resin layer 3
After plating a metal having excellent conductivity such as copper, silver, and gold as a metal or a metal foil from above, as shown in FIG. 10, the metal part on the surface is etched to the size of the component mounting pad. Then, a flat component mounting pad 8 having no via on the surface is formed.

A second embodiment of the pad structure of the wiring board according to the present invention will be described with reference to FIGS. FIG. 11 is a cross-sectional view of the pad structure of the wiring board, and FIGS. 12 to 23 are cross-sectional views of the manufacturing process of the pad structure of the wiring board. In FIG. 11, reference numeral 11 denotes a substrate made of a photosensitive resin, on which an internal wiring 12 is formed. A photosensitive resin layer 13 is formed on the internal wiring 12, and a via 14
Are formed. In the inner surface of the via 14 and in the vicinity of the upper surface of the photosensitive resin layer 13, a conductive material layer 15 for interlayer connection made of a metal having excellent conductivity such as copper, silver, or gold is formed. The inside of the material layer 15 is filled with a conductive filling layer 6 made of a conductive resin in which metal particles having excellent conductivity such as copper, silver, and gold are kneaded in a resin.

Further, a flat layer 17 made of a photosensitive resin is formed at another portion of the upper surface of the photosensitive resin layer 13 so as to be flat in conformity with the upper surface of the conductive material layer 15 for interlayer connection, Component mounting pads 18 are formed on the upper surfaces of the flat layer 17, the interlayer-connecting conductive material layer 15, and the conductive filling layer 16.

Next, the manufacturing method will be described. First,
As shown in FIG. 12, an internal wiring 12 is formed on a surface substrate 11 using a conductive material. As a method of forming the internal wiring 12, a method of plating a metal having excellent conductivity such as copper, silver, and gold, attaching these metal foils, and leaving only necessary portions for the internal wiring 12 chemically or There is a method of removing unnecessary portions by mechanical polishing.

Next, as shown in FIG.
The photosensitive resin layer 13 is formed by applying a photosensitive resin to a certain thickness from above.
After the formation of the photosensitive resin layer 13 as shown in FIG.
Is exposed and developed to form a via 14 serving as a base for drawing out the internal wiring 12 to the surface.

Next, as shown in FIG.
After forming a conductive material layer 15 for interlayer connection by plating a metal having excellent conductivity such as silver or gold, as shown in FIG. 16, the conductive material 15 for interlayer connection is removed by etching while leaving only necessary portions. . Then, as shown in FIG. 17, a photosensitive resin is applied from above to perform exposure and development to form a resin layer, and then, as shown in FIG. 18, exposure and development are performed.
The conductive material layer 15 for interlayer connection of the via 14 is exposed. Then, as shown in FIG. 19, the surface is polished and flattened until the conductive material layer 15 for interlayer connection on the surface is exposed. Further, as shown in FIG. 20, a conductive resin is applied from above, the vias 14 are buried until the conductive resin becomes convex, and then curing is performed.

Then, as shown in FIG. 21, the conductive resin is polished until the surface thereof is flat to form a conductive filling layer 16. Further, as shown in FIG. 22, a metal material having excellent conductivity, such as copper, gold, or silver, is plated or a metal foil is applied thereon to form a metal for a component mounting pad. As shown, the metal portion on the surface is etched to the size of the component mounting pad to form a flat component mounting pad 18 in a surface state.

A third embodiment of the pad structure of the wiring board according to the present invention will be described with reference to FIGS. FIG. 24 is a sectional view of the pad structure of the wiring board, and FIG. 25 is a plan view of the pad structure of the wiring board. In FIG. 24, reference numeral 21 denotes a substrate made of a photosensitive resin.
Are formed. A photosensitive resin layer 23 is formed on the internal wiring 22, and a via 24 is formed in a part thereof. On the inner surface of the via 24 and near the upper surface of the photosensitive resin layer 23, a conductive material layer 25 for interlayer connection made of a metal having excellent conductivity such as copper, silver, or gold is formed. A wall of the solder resist 26 is formed around and around the concave portion of the electric material layer 25 for interlayer connection, and a portion sandwiched between the solder resists 26 is a component mounting pad 27.

In such a pad structure of the wiring board, when the solder paste printed on the component mounting pads 27 is melted, the solder is prevented from flowing into the concave portions of the conductive material layer 25 for interlayer connection.

A fourth embodiment of the pad structure of the wiring board according to the present invention will be described with reference to FIG. FIG. 26 is a plan view of the pad structure of the wiring board. The embodiment shown in this figure
The substrate, internal wiring, photosensitive resin layer, and conductive material layer for interlayer connection are the same as in the third embodiment. In this embodiment, a solder resist 31 is formed in a mesh shape surrounding a concave portion of a conductive material layer 32 for interlayer connection, and a pad 33 for component mounting is formed.
Is subdivided into almost squares.

[0026]

As described above, according to the pad structure of the wiring board of the present invention, even when a component mounting pad is formed at a position where a via is present, the solder does not flow into the concave portion of the via and the solder does not flow. This allows highly reliable component mounting without connection failure.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a pad structure of a wiring board according to the present invention.

FIG. 2 is a sectional view showing a manufacturing process of the first embodiment of the pad structure of the wiring board according to the present invention.

FIG. 3 is a sectional view showing a manufacturing step of the first embodiment of the pad structure of the wiring board according to the present invention;

FIG. 4 is a sectional view showing a manufacturing process of the first embodiment of the pad structure of the wiring board according to the present invention;

FIG. 5 is a sectional view showing a manufacturing step of the first embodiment of the pad structure of the wiring board according to the present invention;

FIG. 6 is a sectional view showing a manufacturing process of the first embodiment of the pad structure of the wiring board of the present invention.

FIG. 7 is a sectional view showing a manufacturing step of the first embodiment of the pad structure of the wiring board according to the present invention.

FIG. 8 is a sectional view showing a manufacturing step of the first embodiment of the pad structure of the wiring board of the present invention.

FIG. 9 is a sectional view showing a manufacturing step of the first embodiment of the pad structure of the wiring board of the present invention.

FIG. 10 is a sectional view showing a manufacturing step of the first embodiment of the pad structure of the wiring board of the present invention.

FIG. 11 is a sectional view of a second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 12 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 13 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board of the present invention.

FIG. 14 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 15 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 16 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 17 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board of the present invention.

FIG. 18 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board of the present invention.

FIG. 19 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 20 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board of the present invention.

FIG. 21 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board according to the present invention.

FIG. 22 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board of the present invention.

FIG. 23 is a sectional view showing a manufacturing step of the second embodiment of the pad structure of the wiring board of the present invention.

FIG. 24 is a sectional view showing a third embodiment of the pad structure of the wiring board according to the present invention;

FIG. 25 shows a plan view of a third embodiment of the pad structure of the wiring board of the present invention.

FIG. 26 is a plan view of a fourth embodiment of the pad structure of the wiring board according to the present invention;

FIG. 27 is a partial cross-sectional view of a conventional wiring board.

FIG. 28 shows a partial cross-sectional view of a conventional wiring board.

FIG. 29 shows a partial cross-sectional view of a conventional wiring board.

[Explanation of symbols]

 1,11,21 substrate 2,12,22 internal wiring 3,13,23 photosensitive resin layer 4,14,24 via 5,15,25 interlayer connection conductive material layer 6 filling layer 7,17 flat layer 8,18 , 27,33 Component mounting pad 26,31 Solder resist

Claims (4)

[Claims] 1. A substrate, an internal wiring formed on the substrate, a photosensitive resin layer formed on the substrate and the internal wiring, a via formed in the photosensitive resin layer to expose the internal wiring, a via, and Interlayer connection conductive material layer formed on the photosensitive resin layer, filling layer filled inside the interlayer connection conductive material layer, and component mounting pad formed on the filling layer and the interlayer connection conductive material layer A pad structure for a wiring board, comprising: 2. The pad structure for a wiring board according to claim 1, wherein the filling layer is formed of a conductive resin. 3. A substrate, an internal wiring formed on the substrate, a photosensitive resin layer formed on the substrate and the internal wiring, a via formed in the photosensitive resin layer to expose the internal wiring, a via, The conductive material layer for interlayer connection formed on the photosensitive resin layer and the solder resist formed around the recess of the conductive material layer for interlayer connection have a conductive material layer for interlayer connection on the photosensitive resin layer. A pad structure for a wiring board, characterized in that parts are used as component mounting pads. 4. The wiring board pad structure according to claim 3, wherein the component mounting pad is subdivided by a solder resist.