JP2000151107A - Multilayer printed wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board and a manufacturing method thereof that has high electrical continuity reliability of laminated through holes and a reduced number of manufacturing processes can make the board thinner. SOLUTION: There are provided a first via hole 31 provided in a first insulating layer 11 and second via holes 30, 32 provided at the positions corresponding to apertures at the upper and lower ends of the first via hole 31. A second insulating layer 10, 12 provided with the second via hole 30, 32 is laminated on at least one of the upper surface side and lower surface side of the first insulating layer 11. The first via hole 31 is a solid hole filled with a conductive filler 7. The second via holes 30, 32 are coated with metal film plating 362 on the inner wall and the bottom part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board and a method of manufacturing the same, and more particularly, to a connection structure between patterns by through holes.

[0002]

2. Description of the Related Art Conventionally, as a multilayer printed wiring board, FIG.
As shown in the figure, a plurality of laminated insulating layers 910, 91
1, 912, a conductor pattern 2 provided on the surface of the insulating layers 910-912, and a through hole 93 for electrically connecting the conductor patterns 2 of each layer. The insulating layers 911 and 912 have mounting holes 4 for mounting electronic components. Solder balls 6 for external connection are joined to the conductor pattern 2 provided on the back surface of the multilayer printed wiring board 90. The multilayer printed wiring board 90 is made of the solder resist 14.
Coated with

The through holes 93 are formed in the respective insulating layers 910-9.
12 has a structure in which via holes 930 provided in the semiconductor device 12 are stacked via a metal layer 931. This laminated structure has an internal insulating layer 9.
11, a via hole 930 is formed by drilling, the opening is covered with a metal layer 931, and insulating layers 910 and 912 made of prepreg are further laminated on the surface as an outermost layer. Via hole 93
0 is formed. In the case of the photo via method, a photosensitive resin is used as a prepreg. A metal plating film 936 is formed in each via hole 930.
A resin 937 is filled in the inside of the via hole 930 provided in the insulating layer 911 as an intermediate layer.

[0004] Even if a via hole 930 having a relatively large diameter is formed in the laminated type through hole 93, the outer opening can be made to have a very small diameter. Can be achieved.

[0005]

However, in the conventional laminated type through hole 93, each via hole 93 is provided.
When the via hole 930 is formed by the laser method, the metal layer 931 provided between 0 may be damaged by the laser. Therefore, it is difficult to form the metal plating film 936 on the surface of the metal layer 931, and the electrical connection reliability of the through hole 93 is low.

In the case of the photo via method, the metal layer 9 is formed.
31 and the metal plating film 936 covering the surface thereof have low adhesion. Therefore, as in the case of the laser method, the electrical conduction reliability of the through hole 93 is low.

Further, since the metal layer 931 has a certain thickness, it prevents the multilayer printed wiring board from being thinned. Further, when the conductor pattern is not provided on the intermediate insulating layer 911, the pattern forming step must be performed only to form the metal layer 931 and the number of manufacturing steps may be increased.

The present invention has been made in view of the above-mentioned conventional problems, and a multilayer printed wiring board which has a high reliability of electrical conduction of a laminated through hole, can realize a thin substrate, and has a small number of manufacturing steps, and a method of manufacturing the same. It seeks to provide a way.

[0009]

According to the present invention, a first insulating layer provided on a first insulating layer is provided.
The semiconductor device includes a via hole and a second via hole provided at a position corresponding to an opening at an upper end or a lower end of the first via hole. The second via hole is formed on at least one of an upper surface side and a lower surface side of the first insulating layer. A multilayer printed wiring board formed by laminating provided second insulating layers, wherein the first via hole is a solid hole filled with a conductive filler therein, and the second via hole is formed of an inner wall and A multilayer printed wiring board having a bottom portion covered with a metal film.

The most remarkable feature of the present invention is that the inside of the first via hole is filled with a conductive filler, and the opening end is covered with the metal film of the second via hole.

The operation and effect of the present invention will be described.
A solid hole in which a conductive filler is filled in a first via hole, and a second via hole laminated on an upper end or a lower end thereof, wherein the inner wall and the bottom are covered with a metal film such as a metal plating film. The coating hole constitutes one laminated through hole. Since the conductive filler is covered with the metal film of the second via hole, electrical connection between the first via hole and the second via hole is reliably performed.

Further, since the conductive filler in the first via hole and the metal film of the second via hole adhere to each other, electrical conduction between the first and second via holes can be obtained. It is not necessary to interpose a metal layer between via holes as in the above. Therefore, there is no need to perform a manufacturing process for forming a metal layer, and the number of manufacturing processes can be reduced. Further, the thickness can be reduced by the thickness of the metal layer.

Next, details of the present invention will be described. The first via hole and the second via hole provided at a position corresponding to the opening form a stacked through hole. It is preferable to use a composite material of a conductive filler and a synthetic resin as the conductive filler filled in the first via hole. When the second via hole is formed by a laser method or a photo via, the conductive filler made of the composite material is
Although a part of the synthetic resin may be removed, the conductive filler is thereby exposed, so that the electrical conductivity of the second via hole with the metal film is rather increased. Therefore, high electrical conduction reliability between the first via hole and the second via hole can be obtained.

The conductive fillers are conductive fillers 30 to 9
It is preferable that it is composed of 0 vol% and 10 to 70 vol% of the synthetic resin. When the conductive filler is less than 30 vol% or the synthetic resin exceeds 70 vol%,
There is a possibility that the conductivity of the conductive filler decreases and the electrical conductivity of the second via hole with the metal film decreases. If the conductive filler exceeds 90 vol% or the synthetic resin is less than 10 vol%, the adhesion to the metal film may be reduced.

The average particle size of the conductive filler is 0.1%.
It is preferably about 5 μm. If the thickness is less than 0.1 μm, the adhesion strength to the metal film may be reduced, and if it is more than 5 μm, the contact area with the metal film may be reduced and the electrical conductivity may be reduced.

When the conductive filler is added to the synthetic resin, it is preferable to mix conductive fillers of different sizes and to add the mixed filler to the synthetic resin. Thereby, a large amount of conductive filler can be mixed with the conductive filler. Further, conductive fillers having substantially the same size may be added to the synthetic resin.

As the conductive filler, for example, Pb,
A simple substance of Zn, Cu, Ag, Ni, Fe, an alloy thereof (for example, lead or the like), or a resin core material coated with the above simple substance or alloy can be used. Also,
Cu, A to inorganic fillers such as alumina and ceramic
It may be one plated with a metal such as g, Ni, or Au.

The synthetic resin contained in the conductive filler is preferably made of, for example, one or more selected from the group consisting of an epoxy resin, bismaleimide triazine, and modified polyimide. This is because the conductive filler can be easily filled into the first via hole.

The wall surface of the first via hole may or may not be coated with a metal film, but is preferably coated. Since the internal conductive filler is electrically connected not only to the metal film at the opening end but also to the metal film on the inner wall of the first via hole, the electrical conduction reliability is improved.

The thickness of the metal film covering the inner wall and the bottom of the second via hole is preferably 1 to 20 μm.
If it is less than 1 μm, the open end of the conductive filler is not uniformly covered, and the electrical connectivity may be reduced. If it exceeds 20 μm, electrical conductivity corresponding to the thickness may not be obtained.

The diameters of the first via hole and the second via hole may be the same or different, and either may be large, but it is preferable that the opening diameter of the outermost layer is small. This is for high-density mounting on the surface of the multilayer printed wiring board.

The laminated structure of the first and second via holes is as follows.
Any number of layers can be repeatedly formed (FIGS. 1 and 6A).
The first via holes serving as solid holes may be continuously stacked. Further, the second via hole serving as the coating hole may be continuously stacked.

The method of manufacturing the multilayer printed wiring board includes, for example, a step of forming a first via hole in a first insulating layer, and a step of forming a conductive filler made of a conductive filler and a synthetic resin in the first via hole. Filling a second insulating layer on the surface of the first insulating layer, and placing the conductive layer on the second insulating layer at a position corresponding to the opening of the first via hole by a laser method or a photo via method. A step of forming a second via hole having a conductive filler as a bottom, and a step of covering an inner wall and a bottom of the second via hole with a metal plating film. .

In the above manufacturing method, the second via hole is formed by a laser method or a photo via method. The laser method refers to a method of irradiating a laser to the second insulating layer to form a hole. The photovia method refers to a method in which a second insulating layer is made of a photosensitive resin, exposed using a photomask, and developed to form a hole.

When the second via hole is formed by the laser method, a part of the synthetic resin in the first via hole constituting the bottom of the second via hole may be burned out by the laser. Also in this case, the laser is reflected by the internal conductive filler, the drilling is stopped, and a part of the conductive filler is exposed. The exposed conductive filler has high adhesion to the metal plating film. When the second via hole is formed by the laser method or the photo via method, the conductive filler at the bottom becomes rough. When the metal plating film is coated on the rough surface, the metal plating film firmly adheres to the rough surface due to the anchor effect.

Therefore, according to the above manufacturing method, excellent adhesion strength of the metal plating film to the conductive filler can be obtained,
In addition, high electrical connection reliability is obtained between the first and second via holes. In the laser method and the photo via method, a second via hole having a small diameter can be formed, so that a multilayer printed wiring board having a high surface mounting density can be manufactured.

The first via hole can be formed by a laser method and a photo via method as in the case of forming the second via hole. It can also be drilled with a drill.

As the insulating layer, a glass epoxy substrate, a porous polyimide substrate, a glass bismaleimide triazine substrate, or the like can be used. Also, prepreg or solder resist can be used. When a photo via method is used, a photosensitive resin is used.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 A multilayer printed wiring board according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the multilayer printed wiring board 1 of the present embodiment has a first via hole 31 provided in a first insulating layer 11 and a second via hole provided at a position corresponding to an opening at an upper end or a lower end of the first via hole 31. And via holes 30 and 32. On the upper surface side and the lower surface side of the first insulating layer 11, the second via holes 30 and 32 are provided.
The insulating layers 10 and 12 are stacked. 1st via hole 3
The first and second via holes 30 and 32 constitute a three-layered through hole 3 that is continuous in the thickness direction of the multilayer printed wiring board 1.

The first via hole 31 is a solid hole in which the conductive filler 7 is filled. The second via holes 30 and 32 have metal plating films 362 on their inner walls and bottom.
It is a covering hole covered with. The conductive filler 7 is a second filler.
The bottom of the via holes 30 and 32 is formed. The open end of the conductive filler 7 is covered with a metal plating film 362 that covers the inner walls and the bottom of the second via holes 30 and 32. The inner wall of the first via hole 31 is also a metal plating film 37.
2 coated.

The conductive filler 7 is composed of 45 vol% of the conductive filler 71 and 55 vol% of the synthetic resin 72. The average particle size of the conductive filler 71 is 0.1 to 5 μm.
It is. Copper is used as the conductive filler 71 and epoxy resin is used as the synthetic resin 72.

The multilayer printed wiring board 1 has mounting holes 4 for mounting electronic components. Conductive patterns 2 are provided on the upper and lower surfaces of the multilayer printed wiring board 1. The surface of the multilayer printed wiring board 1 is solder resist 1
4 is partially covered by the second via hole 3.
It has entered inside 0,32. Others are the same as the conventional example (see FIG. 7).

Next, a method of manufacturing the multilayer printed wiring board of the present embodiment will be described. First, as shown in FIG.
A first insulating layer 11 made of an epoxy resin substrate to which a copper foil 20 is adhered is prepared. A first via hole 31 and a mounting hole 4 for mounting an electronic component are formed in the first insulating layer 11 by a drill.

As shown in FIG. 3B, the inner wall of the first via hole 31 is covered with a metal plating film 372 made of copper. Further, the copper foil 20 is etched to form the first insulating layer 11.
The conductor pattern 2 is formed on the surface of the substrate.

Next, as shown in FIG. 3 (c), a conductive filler 7 having the above composition is prepared, and this is made into a paste with a solvent. Next, the inside of the first via hole 31 is filled with the paste-like conductive filler 7.

Next, as shown in FIG. 4A, second insulating layers 10 and 12 made of prepreg are laminated on the upper and lower surfaces of the first insulating layer 11. The mounting hole 4 is provided in advance on the prepreg to be the uppermost first insulating layer 12. Next, the surfaces of the second insulating layers 10 and 12 are covered with a copper foil 20. Next, the second insulating layers 10 and 12 are cured by heating. Next, a portion of the copper foil 20 covering the second via hole forming portions 300 and 320 and the mounting hole 4 is
A hole is formed by etching to form an opening hole 200.

Next, as shown in FIG. 4B, a laser is irradiated to a position corresponding to the first via hole 31 in the second insulating layers 10 and 12, and the second via hole 30 having the conductive filler 7 as a bottom is irradiated. , 32 are drilled. Next, the inner walls of the second via holes 30 and 32 are covered with a metal plating film 362 made of copper. Further, the copper foil 20 is etched to form the conductor pattern 2 on the surfaces of the second insulating layers 10 and 12. Thereafter, the surfaces of the second insulating layers 10 and 12 are coated with a solder resist to obtain a multilayer printed wiring board (FIG. 7).
reference).

Next, the operation and effect of this embodiment will be described. The conductive filler 7 filled in the first via hole 31 is a composite material of the conductive filler 71 and the synthetic resin 72 and has conductivity. Since the conductive filler 7 is covered with the metal plating film 362 of the second via holes 30 and 32, the second via holes 30 and 32 and the first via hole 31 are electrically connected.

As shown in FIG. 2A, when the second via holes 30 and 32 are drilled by the laser 8, a part of the synthetic resin 72 in the conductive filler 7 located at the bottom is removed and the conductive filler 7 is removed. A part of 71 is exposed. The exposed conductive filler 71 has high adhesion to the metal plating film 362 as shown in FIG. In addition, the laser method
When a via hole is formed, the conductive filler 7 at the bottom becomes rough. When the metal plating film 362 is coated on the rough surface, the metal plating film 362 firmly adheres to the rough surface due to the anchor effect.

Therefore, high electrical connection reliability between the first via hole 31 and the second via holes 30 and 32 can be obtained. Therefore, it is not necessary to interpose a metal layer between via holes as in the related art. Therefore, there is no need to perform a manufacturing process for forming the metal layer, and the thickness can be reduced by the thickness of the metal layer.

Embodiment 2 In this embodiment, as shown in FIG. 5, the content of the conductive fillers 711 and 712 in the conductive filler 7 is 90 V.
ol%, and the content of the synthetic resin 72 is 10 vol%.

The conductive fillers 711 and 712 are of two different sizes. The diameter of the large conductive filler 711 is 20 μm, and the diameter of the small conductive filler 712 is 0.05 μm. Others
This is the same as the first embodiment.

In this example, the conductive fillers 711 and 712 contained in the conductive
It is as large as 0 vol%. This is because the large conductive filler 71
This is because a small conductive filler 712 is filled in the gap 1. The conductive filler 7 containing the conductive filler at a high density as described above is particularly excellent in conductivity. Accordingly, the first via hole 31 in the present example has excellent electrical conductivity with the second via holes 30 and 32 through the conductive filler 7. In addition, also in this example, the first embodiment
The same effect as described above can be obtained.

Embodiment 3 As shown in FIG. 6A, the multilayer printed wiring board of this embodiment has first via holes 31 and 321 and second via holes 3.
0, 33 are provided. The two central layers are the first via holes 31 and 321
And the inside is filled with a conductive filler 7. On the other hand, the second via hole 30,
The inner wall and the bottom are covered with a metal plating film 362. First via holes 31, 32
Reference numeral 1 denotes a second via hole 30 in the first insulating layers 11 and 121,
33 is formed on the second insulating layers 10 and 13. Other configurations of the multilayer printed wiring board of this example are the same as those of the first embodiment.

Next, a method of manufacturing the multilayer printed wiring board of the present embodiment will be described. First, a multilayer printed wiring board having a three-layer structure was manufactured in the same manner as in the first embodiment, and a second
The formation of the insulating layer 13, the formation of the second via hole 33, and the covering of the metal plating film 362 are performed. Thereafter, the surfaces of the laminated first and second insulating layers are covered with a solder resist to obtain the multilayer printed wiring board of the present example. Also in this example, the same effect as in the first embodiment can be obtained.

Embodiment 4 The multilayer printed wiring board of this embodiment has a double-layered through hole 35 composed of a first via hole 31 and a second via hole 32, as shown in FIG. 6B. . First
The bottom of the via hole 31 is covered with the conductor pattern 2.

The first via hole 31 is formed by irradiating the first insulating layer 11 with a laser beam in a state where the conductive pattern 2 is formed on the bottom portion. 1st via hole 3
1 is filled with a conductive filler 7 to form a solid hole. Other configurations are the same as those of the first embodiment. In this example, the same effect as that of the first embodiment can be obtained.

[0048]

According to the present invention, there is provided a multilayer printed wiring board which has high reliability of electrical conduction of a laminated type through hole, can realize a thinned substrate, and has a small number of manufacturing steps, and a method for manufacturing the same. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a multilayer printed wiring board according to a first embodiment.

FIGS. 2A and 2B are explanatory diagrams showing an effect on a conductive filler when a second via hole is formed by a laser method in Embodiment 1 and a case where the conductive filler is covered with a metal plating film; Explanatory drawing (b) which shows the state of FIG.

FIGS. 3A to 3C are diagrams illustrating a method for manufacturing a multilayer printed wiring board according to the first embodiment.

4A and 4B are explanatory diagrams of the method for manufacturing the multilayer printed wiring board, following FIGS.

FIG. 5 is a sectional view of a principal part of a multilayer printed wiring board according to a second embodiment.

6A is a cross-sectional view of a main part of a multilayer printed wiring board according to a third embodiment, and FIG. 6B is a cross-sectional view of a main part of a multilayer printed wiring board according to a fourth embodiment.

FIG. 7 is a sectional view of a conventional multilayer printed wiring board.

[Explanation of symbols]

 1. . . Multilayer printed wiring board, 10, 12, 13. . . Second insulating layer, 11, 121. . . 13. first insulating layer; . . 1. Solder resist, . . Conductor pattern, 30, 32, 33. . . Second via hole, 31, 321. . . First via hole, 362, 372. . . 3. metal plating film; . . 6. mounting holes, . . Conductive filler, 71. . . Conductive filler, 72. . . 7. synthetic resin, . . laser,

Continued on the front page F term (reference) 4E351 AA03 BB01 BB30 BB31 BB33 BB49 CC06 CC11 CC20 DD04 DD05 DD08 DD12 DD19 DD21 DD52 EE01 GG08 GG20 5E346 AA43 CC08 CC31 CC32 DD23 FF07 FF13 FF23 FF37 GG15 HGG17 HH07H

Claims (4)

[Claims] A first via hole provided in the first insulating layer;
A second via hole provided at a position corresponding to an opening at an upper end or a lower end of the first via hole, and a second via hole provided on at least one of an upper surface side and a lower surface side of the first insulating layer. A multilayer printed wiring board comprising two insulating layers laminated, wherein the first via hole is a solid hole filled with a conductive filler therein, and the second via hole has a metal inner wall and a bottom portion. A multilayer printed wiring board characterized by being coated with a film. 2. The conductive filler according to claim 1, wherein the conductive filler comprises 30 to 90 vol% of the conductive filler and 1% of the synthetic resin.
A multilayer printed wiring board comprising 0 to 70 vol%. 3. The multilayer printed wiring board according to claim 1, wherein the conductive filler has an average particle size of 0.1 to 5 μm. 4. A step of forming a first via hole in the first insulating layer, a step of filling the inside of the first via hole with a conductive filler composed of a conductive filler and a synthetic resin,
Laminating a second insulating layer on the surface of the insulating layer; and forming a second insulating layer on the second insulating layer at a position corresponding to the opening of the first via hole by a laser method or a photo via method, using the conductive filler as a bottom. A method for manufacturing a multilayer printed wiring board, comprising: a step of forming two via holes; and a step of covering an inner wall and a bottom of the second via hole with a metal plating film.