JPH11274676A - Multilayer printed wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and highly reliable multilayer printed wiring board. SOLUTION: Insulating base materials 1a and 1b are stacked so that wiring layers 6 face each other. Parts positioned at the peripheries of through holes 4a-4c in respective conductive materials 4 filled in the through holes and the electrode parts 5 of the facing wiring layers 6 are fixed by conductive resin 8 arranged on the through holes 4a-4c and the electrode parts 5 of the wiring layers 6 around the holes.

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 multilayer printed wiring board used for a signal processing circuit of an electronic device such as a television receiver and a method of manufacturing the same. It is.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing the structure of a conventional multilayer printed wiring board. In FIG. 4, a plate-like base material 101a made of an insulating material such as paper or glass fiber impregnated with a synthetic resin is shown. Wiring layer 1 made of copper foil on the front and back surfaces
13a is further provided on the front and back surfaces of the base material 101a via the wiring layer 113a.
a, two substrates 1 similar to the substrate 101a
01b are stacked. A wiring layer 113b made of copper foil is provided on outer surfaces of the two bases 101b. The through holes 103 are formed by the wiring layers 113a and 113b,
01a and the base material 101b, and the ends of the wiring layers 113a and 113b are exposed on the inner wall thereof. A copper plating layer 112 is provided on the inner wall of the through hole 103 and the surface of the base material 101b. The copper plating layer 112 is formed on the wiring layer 113 exposed on the inner wall of the through hole 103.
The wiring layers 113a and 113b are fixed to the ends of the wiring layers 113a and 113b, so that the wiring layer 113a serving as an inner wiring layer and the outer wiring layer 113b are connected to each other. The insulating resin 107 is disposed on the copper plating layer 112 on the front surface and the back surface of the substrate 101b.

[0003]

The conventional multilayer printed wiring board has the above-mentioned structure. However, when a paper impregnated with a phenol resin is used as the base materials 101a and 101b, the coefficient of expansion in the thickness direction due to moisture absorption is large. Therefore, in the conventional connection method, the thin copper plating layer 112 formed on the inner wall of the through hole 103 is used. Wiring layer 113 serving as an inner wiring layer having an extremely small thickness of about 15 to 35 μm.
Stress may be generated at the joint with the end face a, and the joint may be broken. If this joint breaks, contact failure occurs, so that such a multilayer printed wiring board has a problem of low reliability and low practicality.

Accordingly, epoxy resin impregnated glass fibers, which are more expensive than paper impregnated with phenolic resin but have small expansion in the thickness direction due to moisture absorption, are generally used as the base material of the multilayer printed wiring board. Can be On the other hand, in order to form the copper plating layer 112 for connecting each wiring layer, it is indispensable that the surface shape of the inner wall of the through hole 103 is relatively smooth. However, when an epoxy resin-impregnated glass fiber is used as the base material, it is difficult to obtain a sufficiently smooth surface on the inner wall of the through-hole 103 by performing punching with a press as the hole-cutting process. For this reason, a method of forming the through hole 103 using a drill is generally used. However, in this method, a plurality of holes cannot be formed at one time, and the through hole is formed by punching with a press. In this case, the productivity is extremely low and the production cost is high. Therefore, when the glass fiber impregnated with the epoxy resin is used, there is a problem that the multilayer printed wiring board cannot be provided at low cost.

A copper plating layer 1 is formed on the inner wall of the through hole 103.
Instead of forming 12, a through hole is made of a plurality of base materials filled with a synthetic resin containing tens of percent of metal powder as a conductive material, and these are laminated to form a multilayer printed wiring board. However, the wiring layer exposed on the inner wall of the through-hole 103, in particular, the wiring layer 11 which is an inner layer, is considered.
Since the bonding area between the end portion 2a and the synthetic resin to be filled is extremely small, such a material can sufficiently secure the electrical conductivity of the bonding portion, for example, the specific resistance and the allowable current value. In addition, since the above-mentioned stress and the like affect the bonding portion and break the bonding portion, and further degrade the electrical conductivity, practical application is difficult.

[0006] In the plating process for forming the copper plating layer 112, in any of the processes such as the electroless process and the electrolytic process, the places where the installation of the equipment is approved are generally extremely limited. Therefore, it is necessary to perform only the plating process of the process of manufacturing the multilayer printed wiring board in a place different from other steps, and it is possible to form the multilayer printed wiring board in the same place and in a consistent process. There is a problem that it is difficult, productivity is deteriorated, and production cost is increased.

Further, in a conventional multilayer printed wiring board, when a plurality of base materials in a prepreg state are stacked and bonded with a wiring layer interposed therebetween, the stacked base materials are compressed with a strong pressure in the stacking direction. This necessitates the use of a high-pressure press equipment in the laminating step, and the equipment cost and the amount of investment such as installation space have become very large. as a result,
The problem that the cost of the multilayer printed wiring board becomes expensive and the equipment is large, the press equipment cannot be arranged in the same place as the production line in other processes, and no consistent production line organization is provided, resulting in poor productivity. However, there is a problem that the production cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an inexpensive and highly reliable multilayer printed wiring board and a method of manufacturing the same.

[0009]

According to the present invention, there is provided a multilayer printed wiring board comprising a plurality of plate-shaped insulating bases provided with a wiring layer having a predetermined planar shape on at least one of a front surface and a back surface thereof. A through-hole provided so as to penetrate each of the insulating base material and the wiring layer, and a conductive material filled in the through-hole, the plurality of insulating base materials, wherein the wiring layer is While being laminated so as to face each other,
Each of the conductive materials filled in the through-holes and the portion of the wiring layer facing each other, which is located around the through-hole, is a conductive resin disposed on the through-hole and the wiring layer around the through-hole. It is made to be fixed by the.

Further, in the multilayer printed wiring board according to the present invention, a region other than the region where the conductive resin is provided between the laminated insulating substrates is fixed by the insulating resin. It was made.

Further, in the multilayer printed wiring board according to the present invention, the plurality of insulating bases are laminated so that at least one of the through holes overlaps each other and faces each other, and is embedded in these through holes. Each conductive material is fixed by the conductive resin.

Further, in the multilayer printed wiring board according to the present invention, the conductive resin is used as a conductive material and a metal powder is tens of%.
And a synthetic resin exhibiting conductivity in a solidified state.

Further, the multilayer printed wiring board according to the present invention comprises, as a filler, the insulating resin, an electrically insulating filler having a particle size distributed within a predetermined range, and a latent heat hardening material. This is a synthetic resin.

Further, in the multilayer printed wiring board according to the present invention, the conductive material may be a conductive material containing tens of percent of metal powder.
And a synthetic resin exhibiting conductivity in a solidified state.

Further, in the multilayer printed wiring board according to the present invention, the conductive material is an alloy.

Further, in the method of manufacturing a multilayer printed wiring board according to the present invention, a plurality of plate-like insulating base materials are prepared, and a wiring layer is provided on each of the insulating base materials on at least one of the front surface and the back surface. After forming, a step of forming a through-hole penetrating the wiring layer and the insulating base material, a step of filling a conductive material in the through-hole, and the respective insulating base materials, After laminating so as to face each other, a step of fixing the conductive material in the through hole and the wiring layer facing each other with a conductive resin disposed on the through hole and a wiring layer around the through hole. It is prepared for.

Further, in the method for manufacturing a multilayer printed wiring board according to the present invention, the above-mentioned insulating base materials are laminated so that at least one of their through holes overlaps and faces each other, and the conductive material in each of the above through holes is formed. A step of fixing the material and the wiring layers facing each other with a conductive resin disposed on each of the through holes and on the wiring layers around the through holes.

Further, the method of manufacturing a multilayer printed wiring board according to the present invention includes a step of patterning the wiring layer into a predetermined planar shape as a post-step of the step of forming the wiring layer. Things.

Further, in the method for manufacturing a multilayer printed wiring board according to the present invention, after the step of filling the through hole with a conductive material, the conductive resin is coated on the through hole and a wiring layer around the through hole. The step of fixing with the conductive resin, including the disposing step, is performed by solidifying the conductive resin.

Further, in the method of manufacturing a multilayer printed wiring board according to the present invention, the wiring layer of the insulating base material may be provided between the step of filling the through hole with a conductive material and the step of disposing a conductive resin. A step of arranging an insulating resin in a region other than a region on the wiring layer around the through hole and the periphery of the surface on which the insulating resin is formed. After laminating the insulating base material, the insulating resin And fixing the regions of the insulating base material where the conductive resin is not provided.

Further, in the method of manufacturing a multilayer printed wiring board according to the present invention, the wiring layer of the insulating base may be provided between the step of forming the through hole and the step of filling the through hole with a conductive material. Has a step of disposing an insulating resin in a region other than a region on the wiring layer around the through-hole and the periphery thereof, and a step of filling the through-hole with a conductive material, This is performed by injecting a conductive material only into the through hole. After laminating the insulating substrate, the insulating resin is solidified, and the conductive resin of the insulating substrate is not provided. The method includes a step of fixing the regions.

Further, in the method of manufacturing a multilayer printed wiring board according to the present invention, the wiring layer of the insulating base material is formed between the step of forming the wiring layer and the step of forming the through hole. A step of arranging an insulating resin in a region excluding a region where the through hole is formed and a region on the wiring layer around the through hole, and laminating the insulating base material, A step of solidifying the conductive resin to fix regions of the insulating base material where the conductive resin is not provided.

Further, in the method for manufacturing a multilayer printed wiring board according to the present invention, the conductive resin is a synthetic resin containing tens of percent of metal powder as a conductive material and having conductivity in a solidified state.

Further, in the method of manufacturing a multilayer printed wiring board according to the present invention, the insulating resin may include, as a filler, an electrically insulating filler having a particle diameter distributed within a predetermined range;
It is a synthetic resin blended with a heat latent curing material.

Further, in the method of manufacturing a multilayer printed wiring board according to the present invention, the conductive material is a synthetic resin which contains several tens% of metal powder as a conductive material and exhibits conductivity in a solidified state.

In the method of manufacturing a multilayer printed wiring board according to the present invention, the step of embedding the through hole with a conductive material using the conductive material as an alloy may be performed by heating and melting the alloy. This is performed by pouring into the through-hole and cooling it.

[0027]

FIG. 1 is a sectional view showing the structure of a multilayer printed wiring board according to an embodiment of the present invention (FIG. 1A).
FIG. 1B is a view showing the structure of the main part A (FIG. 1 (b)), and FIG. 1C is a view showing the structure of the main part B thereof (FIG. 1C). On the front and back surfaces of the plate-like base materials 1a and 1b made of the above materials, wiring layers 6 made of a metal layer such as a copper foil having a predetermined planar shape and provided with bonding electrode portions 5 are provided. Have been. Substrate 1a
In the region where the electrode portion 5 is provided, through holes 4a and 4b penetrating the electrode portion 5 and the base material 1a are provided.
A through hole 4c penetrating the electrode portion 5 and the substrate 1b is provided in a region of the substrate 1b where the electrode portion 5 is provided. The conductive resin 4 is filled in the through holes 4a to 4c. As an example of the conductive resin, a thermosetting synthetic resin having conductivity in a solidified state, in which metal powder such as copper powder is compounded by several tens%, may be mentioned. Further, a conductive resin 8 made of the same conductive resin material as described above is arranged on the regions on the through holes 4a to 4c and the region including at least a part of the electrode portion 5 around the through holes 4a to 4c. And is fixed to the conductive resin 4 in the through holes 4a to 4c. The conductive resin 8 is also arranged at a position facing the through hole 4b of the base 1b. The bonding electrode portion 5 is fixed to the conductive resin 4 at a portion 5a exposed on the inner wall of the through-holes 4a to 4c, and is connected to the through-holes 4a to 4c.
The portion 5b exposed around the periphery 4c is fixed to the conductive resin 8. The base material 1a is disposed on the base material 1b such that the through holes 4a and 4c overlap when viewed from above the base materials 1a and 1b. Except for the region where the conductive resin 8 is provided, the electrically insulating filler 2a such as silica or glass beads and the thermally latent curing material 2b And an insulating resin 7 which is an adhesive synthetic resin film having an insulating property, and the base materials 1a and 1b are fixed to each other by the insulating resin 7 and laminated. Further, the base material 1a,
The conductive resins 8 on the opposing surfaces of the base 1b are fixed to each other, and as a result, the wiring layer 6 provided on the back surface of the base 1a and the surface of the base 1b, that is, the wiring layer serving as the inner wiring layer 6, the electrode portions 5 around the through holes 4 a to 4 c are connected to each other via a conductive resin 8. The wiring layer 6 serving as an inner layer sandwiched between the substrates 1a and 1b is
It is taken out of the multilayer printed wiring board via the conductive resin 8 and the conductive resin 4 filled in the through holes 4a to 4c. Wiring layer 6 provided on front and back surfaces of substrate 1a
The portions other than the electrode portion 5 are electrically insulated from each other by sandwiching the substrate 1a. In addition, portions of the wiring layer 6 provided on the front surface and the back surface of the base 1b other than the electrode portions 5 maintain electrical insulation from each other by sandwiching the base 1b. In addition, the portions of the wiring layer 6 on the mutually facing surfaces of the base materials 1a and 1b other than the electrode portions 5 ensure electrical insulation by sandwiching the insulating resin 7.

FIGS. 2A to 2D are cross-sectional views showing a method for manufacturing a multilayer printed wiring board according to an embodiment of the present invention. In the drawing, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. Is shown. Hereinafter, the manufacturing method will be described with reference to FIG. First, base materials 1a and 1b are prepared, and a wiring layer 6 such as a copper foil is provided on one or both surfaces thereof. As a method of forming the wiring layer 6, for example, a commonly used hot press lamination molding method, that is, a metal foil is arranged on the base material 1 in a prepreg state, and the metal foil is heated by a hot press machine. A method of compressing and pasting is used. And FIG.
As shown in (a), the substrates 1a, 1
The through holes 4a to 4c are provided at predetermined positions of b by pressing or the like.

Next, a conductive thermosetting synthetic resin paste containing several tens percent of copper powder was applied to the surfaces of the substrates 1a and 1b, and a rubber squeegee was pressed on the surfaces of the substrates 1a and 1b. After the conductive synthetic resin paste is pressed into the through holes 4a to 4c by moving the conductive synthetic resin paste into the through holes 4a to 4c, the conductive synthetic resin paste is compressed while being heated from both sides of the base materials 1a and 1b. The conductive resin 4 which is hardened and is arranged to fill the through holes 4a to 4c is provided. Thereafter, the conductive synthetic resin adhered to the surface of the wiring layer 6 other than in the through holes 4a to 4c is removed by means such as polishing.

Subsequently, as shown in FIG. 2B, the wiring layers 6 on both surfaces of the base materials 1a and 1b are patterned by a normal subtraction method such as etching to form a metal wiring having a predetermined planar shape. And a wiring layer 6 composed of a bonding electrode portion 5
To form Note that the through holes 4 a to 4 c are arranged in the electrode unit 5. Note that the through holes 4 a to 4 c need not necessarily be located on the electrode portion 5 as long as they are located on the wiring layer 6.

Next, as an insulating resin, the particle diameter is 10 μm.
m, an electrically insulating filler 2a such as silica or glass beads having an electrically insulating property, and a latent heat hardener 2
b, that is, a one-pack type thermosetting conductive synthetic resin paste containing a curing material that is gradually cured by heat is applied to the regions on the substrates 1a and 1b excluding the regions around the through holes 4a to 4c. , Preferably the substrate 1a, 1b excluding the region on the electrode portion 5
The upper region is coated with a screen printing method or the like to form an insulating resin 7, which is then subjected to a treatment such as heating or irradiation with ultraviolet light, so as to be in a pre-cured state, a so-called B-stage cured state.

Next, as shown in FIG. 2 (c), a metal powder such as copper powder is mixed as a conductive synthetic resin with tens of% and a latent heat hardener or the like. The one-pack type thermosetting synthetic resin paste having the above-mentioned shape includes at least a part of the region on the through-holes 4a to 4c on both surfaces of the base materials 1a and 1b by means of a screen printing method or the like, and at least a part of the electrode part 5 around the same. The conductive resin 8 is formed in a region, preferably in a region that coincides with the region on the electrode portion 5, and is subjected to a heat treatment to bring it into a pre-cured state, that is, a B-stage cured state.

Next, as shown in FIG.
On the base material 1b, the through holes 4a, 4c are formed in the base materials 1a, 1b.
The substrates 1a and 1b thus overlapped are sandwiched between normal hot-pressing devices, that is, a hot platen 10 which can be pressed while being heated.
A pressure is applied between the front surface of the substrate a and the back surface of the base material 1b to compress and heat the electric insulating resin 7 and the conductive resin 8 to a completely cured state. As a result, the superposed substrates 1a and 1b are fixed to each other with the insulating resin 7 and the conductive resin 8 to obtain a multilayer printed wiring board as shown in FIG.

When the compression and heating are performed by the hot pressing device, the PET resin film 9 and the like are arranged on the surface of the hot platen 10 of the hot pressing device that is in contact with the substrates 1a and 1b. The release of the substrates 1a and 1b from the hot platen 10 of the pressing device becomes easy.

In the first embodiment, FIG.
As shown in (c), the base materials 1a,
1b, two wiring layers 6 serving as inner wiring layers
The electrode portion 5 is directly connected to the conductive synthetic resin 4 embedded in the through holes 4a to 4c at the portion 5a exposed on the inner walls of the through holes 4a and 4c,
The portions 5b around the parts a to 4c are connected via the conductive resin 8. Thereby, the electrode portion 5 of the inner wiring layer 6 is taken out of the base materials 1a and 1b by the conductive resin 4 and the conductive resin 8.

In the first embodiment, the conductive synthetic resin 4 and the conductive synthetic resin 8 for extracting the electrode portion 5 of the inner wiring layer 6 to the outside of the bases 1a and 1b are:
Since the electrode portion 5 of the inner layer is fixed to the electrode portion 5 at both the portion 5a exposed on the inner wall of the through holes 4a to 4c and the portion 5b around the through holes 4a and 4c, the conventional electrode portion 5 is fixed. As described in the technology, the plating for taking out the connection with the inner wiring layer on the outside of the substrate is bonded only at the end exposed inside the inner wiring layer and the through hole. In contrast, the bonding area between the electrode portion 5 of the inner wiring layer 6 and the conductive resin 4 and the conductive resin 8 can be made sufficiently large. As a result, it is possible to increase the resistance of the joint to the stress stress, to prevent the occurrence of a joint failure to the stress stress, and to reduce the specific resistance of the joint to improve the electrical continuity, thereby tolerating the joint. There is an effect that the current value can be made large enough to withstand practical use. In addition, since the joint portion has improved resistance to stress, paper impregnated with a phenol resin which is easily expanded can be used as the base material. For this reason, it is possible to use relatively inexpensive paper impregnated with a phenol resin and a relatively inexpensive material, and it is possible to provide a multilayer printed wiring board at low cost.

In addition, since the conductive synthetic resins 4 and 8, which are materials having less stress concentration, are used for bonding to the inner electrode portion 5 in the inner layer, there is an effect that the resistance to stress stress can be further increased.

The distance between the wiring layers, which are the inner wiring layers facing each other, between the base materials 1a and 1b is determined by the thickness of the insulating resin 7 in the B-stage cured state. The thickness of the insulating resin 7 is larger than the particle size of the filler 2 in the insulating resin 7. Therefore, the interval between the wiring layers 6 which are the inner layers facing each other can be maintained at a sufficient thickness to maintain the insulating property, and the reliability thereof can be extremely high.

Further, in the above-mentioned conventional multilayer printed wiring board, when a plurality of base materials are laminated and joined together, it is necessary to compress them with a strong pressure. However, in the multilayer printed wiring board according to the first embodiment, the substrates 1a and 1b
Since they are fixed to each other by the insulating resin 7 and the conductive resin 8, such high-pressure press equipment is not required, and a relatively inexpensive and small-sized hot-pressing apparatus can be used.
The production cost can be reduced, and the production can be performed by consistent production line organization, thereby improving the productivity.

In the first embodiment, when laminating the substrates, the conductive resin 8 and the insulating resin 7 are used to fix the substrates to each other. There is no need to laminate the base material, and there is an effect that the handling of the base material at the time of manufacturing can be facilitated and the productivity can be improved.

In the first embodiment, since the through holes 4a to 4c are buried with the conductive resin 4, the step of forming plating on the inner wall of the through hole as in the prior art is not required. As described above, the installation location of the equipment is not limited, and the manufacturing process of the multilayer printed wiring board can be performed in a consistent process, and the productivity can be improved and the production cost can be reduced.

In the first embodiment, since the through holes 4a to 4c are embedded with the conductive resin 4, smoothness and high precision are required for the finish of the inner wall of the through holes 4a to 4c. Since it is not performed, a punching method by press working is also possible as a method of drilling the through holes 4a to 4c, and there is an effect that productivity can be improved by performing such a punching method.

Although the first embodiment has been described with reference to the case where the conductive resin and the insulating resin are formed on each of the surfaces of the two base materials facing each other, the present invention relates to a case where two base materials are formed. Even when the conductive resin and the insulating resin are formed only on one of the surfaces facing each other, the same effect as in the first embodiment can be obtained.

Embodiment 2 3 (a) to 3 (d) are process diagrams showing a method for manufacturing a multilayer printed wiring board according to Embodiment 2 of the present invention, in which the same reference numerals as those in FIG. 2 denote the same or corresponding parts. I have. Hereinafter, the manufacturing method will be described with reference to FIG. First, the base materials 1a and 1b are prepared, a wiring layer 6 made of a metal foil such as a copper foil is provided on one or both surfaces thereof, and the wiring layer 6 is patterned by a subtraction method such as etching to obtain a predetermined planar shape. A wiring layer 6 including the metal wiring and the bonding electrode portion 5 is formed. Then, as shown in FIG. 3A, through holes 4a to 4c penetrating the electrode portion 5 and the base materials 1a and 1b are provided in the region inside the electrode portion 5. The through hole 4a
After forming the layers 4c to 4c, the wiring layer 6 may be patterned.

Next, an insulating synthetic resin paste is applied to the areas on the base materials 1a and 1b except for the area around the through holes 4a to 4c by screen printing or the like to form an insulating resin 7. Is subjected to a treatment such as heating or irradiation with ultraviolet light, so that a pre-cured state, a so-called B-stage cured state is obtained. The step of forming the through holes 4a to 4c may be a step subsequent to the step of forming the insulating resin 7.

Next, as shown in FIG.
On the surface of 1b, a conductive thermosetting synthetic resin paste containing several tens% of copper powder is filled only in the through holes 4a to 4c by a method using a mask such as a screen printing method.
At this time, since the insulating resin 7 is formed on the surface of the base materials 1a and 1b except the periphery of the through holes 4a to 4c, even if the conductive resin paste slightly overflows from the through holes 4a to 4c. When the insulating resin 7 serves as a wall, the conductive resin can be prevented from spreading on the substrates 1a and 1b, and the surface can be prevented from being contaminated. And the substrate 1
The conductive synthetic resin paste is hardened by heating from both sides of a and 1b, and the conductive synthetic resin 4 arranged to fill the through holes 4a, 4b and 4c is provided.

Next, as shown in FIG. 3 (c), the conductive synthetic resin paste is applied to the areas on the through holes 4a, 4b, 4c on both surfaces of the base materials 1a, 1b by means such as screen printing.
Then, the conductive resin 8 is formed on the area around the conductive resin 8 and heat-treated to be in a pre-cured state, that is, a B-stage cured state.

Thereafter, as shown in FIG.
On the substrate 1b, the through holes 4a, 4c are
Are overlapped when viewed from above, and the overlapped base materials 1a and 1b are compressed by applying pressure between the front surface of the base material 1a and the back surface of the base material 1b, and heated to form an electrically insulating resin 7 Then, the conductive resin 8 is completely cured. Thus, the superposed substrates 1a and 1b are fixed to each other by the insulating resin 7 and the conductive resin 8, and a multilayer printed wiring board similar to that shown in FIG.

In the second embodiment, the same effects as in the first embodiment can be obtained, and the through holes 4a to 4a
Since the conductive resin can be filled in the screen c using a method using a mask such as screen printing in the screen, the conductive resin adhered to the front surface and the back surface of the base material as in the first embodiment. This eliminates the need for a step of removing the conductive resin, and has the effect that a multilayer printed wiring board can be easily obtained.

Embodiment 3 5 (a) to 5 (e) are views showing main steps of a method for manufacturing a multilayer printed wiring board according to Embodiment 3 of the present invention. Instead of providing a conductive resin as a conductive material in the hole, an alloy is provided. In the figure, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts.

Next, the manufacturing method will be described with reference to FIG.
5 (a) to 5 (d) show only the process for the substrate 1a, but the same process is performed for the substrate 1b. First, as shown in FIG.
b, a wiring layer 6 having an electrode portion 5 is formed, and an insulating film 7 made of an insulating resin is formed on the front and back surfaces of the substrates 1a and 1b. Further, as shown in FIG. 5B, through holes 4a to 4c are provided so as to penetrate the electrode portion 5 of the wiring layer 6 and the bases 1a and 1b.

Next, an alloy that has been melted by heat is prepared and injected into the through holes 4a to 4c. In this injection, for example, as shown in FIG. 5 (c), a gas injection port 53 for pressurization is provided at the upper part, and a size larger than these through holes is provided at a position corresponding to the through holes 4a to 4c at the lower part. An injection device 55 comprising a container 50 having a small discharge hole 51 and a heating heater 52 disposed inside the container 50 is prepared.
The alloy is kept in a heat-melted state by heating it at 2 and keeping it at a high temperature, and pressurized gas is injected from the upper injection port to discharge the hot-melted alloy from the lower discharge hole of the injection device. This can be easily performed by injecting this into the through holes 4a to 4c. Thereafter, as shown in FIG. 5D, the injected alloy 53 is cooled and solidified. The alloy may be any alloy that can be melted. For example, an alloy of 90% tin and 10% silver, an alloy of 99% tin and 1% germanium, and the like can be used. Thereafter, as in the steps after FIG. 3D, the conductive resin 8 is formed, and the base materials 1a and 1b are joined to obtain a multilayer printed wiring board as shown in FIG. 5E.

In the third embodiment, the same effects as in the second embodiment can be obtained, and the through holes 4a to 4c
Filling and solidification can be completed in a very short time by using an alloy as the conductive material to be disposed on the inner layer. The electrical conductivity of the junction with the wiring layer 6, that is, the specific resistance value, can be increased, and a large current capacity can be obtained. This has the effect of improving both processing cost and electrical performance.

In the first to third embodiments,
Although the multilayer printed wiring board in which two layers of base materials are stacked has been described, in the present invention, even when three or more layers of base materials are stacked, the same effects as those of the first to third embodiments can be obtained.

[0055]

As described above, according to the present invention, a plurality of plate-shaped insulating bases provided with a wiring layer having a predetermined planar shape on at least one of the front surface and the back surface, and each of these insulating bases A through hole provided so as to penetrate the material and the wiring layer, and a conductive material filled in the through hole, wherein the plurality of insulating base materials are laminated so that the wiring layers face each other. The conductive material filled in the through-hole and the portions of the wiring layers facing each other, which are located around the through-hole, are arranged on the through-hole and on the wiring layer around the through-hole. The conductive material and the conductive resin for taking out the inner wiring layer to the outside of the base material have a sufficiently large area to be bonded to the inner wiring layer because the inner wiring layer is fixed to the inner wiring layer. The joint can be That resistant by increasing, it is possible to prevent the occurrence of defective bonding to stress stress,
By reducing the specific resistance of the junction and improving the electrical conductivity, the allowable current value of the junction can be made large enough to withstand practical use. In addition, since a conductive resin, which is a material having less stress concentration, is used for bonding to the inner wiring layer, resistance to stress stress can be further increased. further,
It is possible to use a paper impregnated with a relatively inexpensive phenol resin as a base material by increasing the resistance of the joint to stress. This has the effect of providing a low-cost, highly reliable multilayer printed wiring board.

Further, since the through holes 4a to 4c are buried with a conductive material, the installation place of the equipment is not limited as in the plating step, and the manufacturing process of the multilayer printed wiring board can be performed in a consistent process. The productivity can be improved, the production cost can be reduced, and the multilayer printed wiring board can be provided at low cost.

Further, since the through-holes are embedded with a conductive material, smoothness and high precision are not required for finishing the inner walls of these through-holes. A method is also possible. By performing such a punching method, productivity can be improved, and there is an effect that a multilayer printed wiring board can be provided at low cost.

Further, in the multilayer printed wiring board according to the present invention, the region other than the region where the conductive resin is provided between the laminated insulating substrates is fixed by the insulating resin. Accordingly, the base materials are joined together with a conductive resin and an insulating resin, so that high-pressure press equipment is not required, and a relatively inexpensive and small-sized hot-pressing apparatus can be used. Further, since the base material is fixed by using the conductive resin and the insulating resin, it is not necessary to laminate the base material in a prepreg state as in the conventional case, and the handling of the base material during manufacturing is facilitated, and the productivity is improved. Can be improved. This has the effect of providing a low-cost and highly reliable multilayer printed wiring board.

Further, according to the present invention, the plurality of insulating bases are stacked so that at least one of the through holes overlaps each other and faces each other, and each conductive material embedded in these through holes is provided. Since they are fixed to each other by the conductive resin, there is an effect that an inexpensive and highly reliable multilayer printed wiring board can be provided.

Further, according to the present invention, the conductive resin is a synthetic resin containing several tens% of metal powder as a conductive material and exhibiting conductivity in a solidified state. There is an effect that a wiring board can be provided.

Further, according to the present invention, the above-mentioned insulating resin is used as a filler, and a synthetic resin in which an electrically insulating filler having a particle size distributed within a predetermined range and a heat latent curing material are blended. Therefore, the interval between the inner wiring layers facing each other can be maintained at a sufficient thickness to maintain insulation.
Its reliability can be assured extremely high, inexpensive,
In addition, there is an effect that a highly reliable multilayer printed wiring board can be provided.

Further, according to the present invention, since the conductive material is a synthetic resin containing several tens of percent of metal powder as a conductive material and exhibiting conductivity in a solidified state, a stress is exerted on bonding with an inner wiring layer. As a conductive resin that is a material with less concentration, there is an effect that resistance to stress can be further increased, and an inexpensive and highly reliable multilayer printed wiring board can be provided.

Further, according to the present invention, since the conductive material is made of an alloy, there is an effect that the conductivity of the junction with the inner wiring layer can be improved.

According to the present invention, a plurality of plate-like insulating base materials are prepared, and a wiring layer is formed on at least one of the front surface and the back surface of each insulating base material. Forming a through-hole penetrating through the insulating substrate, and filling a conductive material into the through-hole, and laminating the insulating substrates so that the wiring layers face each other. A step of fixing the conductive material in the through-hole and the wiring layer facing each other with a conductive resin disposed on the through-hole and the wiring layer around the through-hole, so that the cost is reduced. Thus, there is an effect that a highly reliable multilayer printed wiring board can be provided.

According to the present invention, each of the insulating substrates is laminated so that at least one of its through holes overlaps and faces each other, and the conductive material in each of the through holes faces each other. And a step of fixing the wiring layer with a conductive resin disposed on each of the through holes and on the wiring layer around the through hole, so that an inexpensive and highly reliable multilayer printed wiring board is provided. There is an effect that can be.

Further, according to the present invention, as a step subsequent to the step of forming the wiring layer, the step of patterning the wiring layer so as to have a predetermined planar shape is included. There is an effect that a multilayer printed wiring board having high performance can be provided.

According to the present invention, after the step of filling the through hole with a conductive material, the method further comprises the step of disposing the conductive resin on the through hole and on a wiring layer around the through hole. Since the step of fixing with a conductive resin is performed by solidifying the conductive resin, there is an effect that an inexpensive and highly reliable multilayer printed wiring board can be provided.

According to the present invention, between the step of filling the through hole with a conductive material and the step of disposing a conductive resin, the surface of the insulating base material on which the wiring layer is formed is formed. Disposing an insulating resin in a region other than the region on the wiring layer around the through hole and surrounding the insulating hole. After laminating the insulating base material, the insulating resin is solidified to form the insulating resin. Since the method includes the step of fixing the regions of the conductive base material where the conductive resin is not provided, it is possible to provide an inexpensive and highly reliable multilayer printed wiring board.

According to the present invention, between the step of forming the through hole and the step of filling the through hole with a conductive material, the surface of the insulating base on which the wiring layer is formed is formed. The step of disposing an insulating resin in a region other than the region on the wiring layer surrounding the through hole and the step of filling the conductive material into the through hole. Is performed by injecting a conductive material, and after laminating the insulating base material, solidifying the insulating resin, and fixing the regions of the insulating base material where the conductive resin is not provided to each other. Since it is included, the step of removing the conductive material outside the base material is not required, and there is an effect that the multilayer printed wiring board can be easily provided.

Further, according to the present invention, between the step of forming the wiring layer and the step of forming the through hole, the through hole on the surface of the insulating substrate on which the wiring layer is formed is provided. A step of arranging an insulating resin in a region excluding a region where holes are formed and a region on a wiring layer around the hole, after laminating the insulating base material, solidifying the insulating resin, Since the step of fixing the regions of the insulating base material where the conductive resin is not provided is included, it is possible to provide an inexpensive and highly reliable multilayer printed wiring board.

According to the present invention, since the conductive resin is a synthetic resin which contains metal powder as a conductive material and has a solid state and exhibits conductivity in a solid state, it is inexpensive and highly reliable. There is an effect that a printed wiring board can be provided.

Further, according to the present invention, the insulating resin is, as a filler, a synthetic resin blended with an electrically insulating filler having a particle diameter distributed within a predetermined range, and a heat latent curing material. Therefore, there is an effect that a multilayer printed wiring board which is inexpensive and has high reliability can be provided. Also,
According to the present invention, since the conductive material is a synthetic resin containing tens of percent of metal powder as a conductive material and exhibiting conductivity in a solidified state, an inexpensive and highly reliable multilayer printed wiring board is provided. There is an effect that can be.

Further, according to the present invention, the step of embedding the through hole with a conductive material using the conductive material as an alloy is performed by pouring the alloy into the through hole while heating and melting the alloy. Is performed by cooling, the effect of being able to provide a multilayer printed wiring board with improved conductivity at the junction with the inner wiring layer is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a structure of a multilayer printed wiring board according to Embodiment 1 of the present invention.

FIG. 2 is a sectional view illustrating the method for manufacturing the multilayer printed wiring board according to Embodiment 1 of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a multilayer printed wiring board according to Embodiment 2 of the present invention.

FIG. 4 is a sectional view showing the structure of a conventional multilayer printed wiring board.

FIG. 5 is a sectional view illustrating a method for manufacturing a multilayer printed wiring board according to Embodiment 3 of the present invention.

[Explanation of symbols]

 1a, 1b, 101a, 101b Base material 2a Electrically insulating filler material 2b Latent thermal curing material 4a to 4c, 103 Through hole 4 Conductive resin 5 Electrode part 5a Part exposed to inner wall of through hole 5b Part around through hole 6 , 113a, 113b Wiring layer 7, 107 Insulating resin 8 Conductive resin 50 Container 51 Discharge hole 52 Heater 53 Alloy 54 Gas injection port 55 Injection device 112 Copper plating layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/46 H05K 3/46 SG

Claims (18)

[Claims] 1. A plurality of plate-shaped insulating bases provided with a wiring layer having a predetermined planar shape on at least one of a front surface and a rear surface thereof, and penetrating each of these insulating base materials and the wiring layer. And a conductive material filled in the through-hole. The plurality of insulating bases are stacked so that the wiring layers face each other, and the through-hole is formed in the through-hole. A portion of each of the filled conductive materials and the wiring layer facing each other, which is located around the through hole, is fixed by a conductive resin disposed on the through hole and the wiring layer around the through hole. A multilayer printed wiring board characterized by the following. 2. The multilayer printed wiring board according to claim 1, wherein a region other than the region where the conductive resin is provided between the laminated insulating substrates is fixed by the insulating resin. A multilayer printed wiring board characterized by the following. 3. The multilayer printed wiring board according to claim 1, wherein the plurality of insulating substrates are stacked so that at least one of the through holes overlaps each other and faces each other, and is embedded in these through holes. Wherein each of the obtained conductive materials is fixed to each other by the conductive resin. 4. The multilayer printed wiring board according to claim 1, wherein the conductive resin contains tens of percent of metal powder as a conductive material.
A multilayer printed wiring board, which is a synthetic resin exhibiting conductivity in a solidified state. 5. The multilayer printed wiring board according to claim 1, wherein the insulating resin comprises, as a filler, an electrically insulating filler whose particle diameter is distributed within a predetermined range; A multilayer printed wiring board characterized by being a synthetic resin containing 6. The multilayer printed wiring board according to claim 1, wherein the conductive material contains tens of percent of metal powder as a conductive material.
A multilayer printed wiring board, which is a synthetic resin exhibiting conductivity in a solidified state. 7. The multilayer printed wiring board according to claim 1, wherein the conductive material is an alloy. 8. A plurality of plate-shaped insulating base materials are prepared, and a wiring layer is formed on at least one of the front surface and the back surface of each of the insulating base materials. Forming a through hole that penetrates, and filling a conductive material in the through hole, and laminating each of the insulating base materials so that the wiring layers face each other, Manufacturing a multilayer printed wiring board, comprising: a step of fixing the conductive material and the wiring layer facing each other with a conductive resin disposed on the through hole and a wiring layer around the through hole. Method. 9. The method for manufacturing a multilayer printed wiring board according to claim 8, wherein each of the insulating base materials is laminated so that at least one of the through holes overlaps each other and faces each other. A step of fixing the conductive material and the wiring layers facing each other with a conductive resin disposed on each of the through holes and on the wiring layers around the through holes. Production method. 10. The method for manufacturing a multilayer printed wiring board according to claim 8, further comprising a step of patterning the wiring layer so as to have a predetermined planar shape as a post-step of forming the wiring layer. A method for manufacturing a multilayer printed wiring board, comprising: 11. The method for manufacturing a multilayer printed wiring board according to claim 8, wherein after the step of filling the through hole with a conductive material, the conductive layer is formed on the through hole and on a wiring layer around the through hole. A method for manufacturing a multilayer wiring printed circuit board, comprising a step of disposing a resin, and the step of fixing with the conductive resin is performed by solidifying the conductive resin. 12. The method for manufacturing a multilayer printed wiring board according to claim 11, wherein the step of filling the through hole with a conductive material and the step of arranging a conductive resin are performed. A step of arranging an insulating resin in a region other than a region on the wiring layer on the surface on which the wiring layer is formed, excluding the through hole and the surrounding wiring layer; A method for manufacturing a multilayer wiring printed circuit board, comprising a step of solidifying a conductive resin to fix regions of the insulating base material where the conductive resin is not provided. 13. The method for manufacturing a multilayer printed wiring board according to claim 11, wherein the step of forming the through-hole and the step of filling the through-hole with a conductive material are performed. A step of disposing an insulating resin in a region on the surface on which the wiring layer is formed, excluding the through hole and a region on the wiring layer around the through hole, and filling the through hole with a conductive material Is performed by injecting a conductive material only into the through-hole. After laminating the insulating base material, the insulating resin is solidified, and the conductive resin of the insulating base material is provided. A method for manufacturing a multilayer printed wiring board, comprising a step of fixing unexposed regions to each other. 14. The method for manufacturing a multilayer printed wiring board according to claim 11, wherein the wiring layer of the insulating base material is formed between the step of forming the wiring layer and the step of forming the through hole. Having a step of arranging an insulating resin in a region excluding a region where the through hole is formed and a region on the wiring layer around the region where the through hole is formed, after laminating the insulating base material, A method for manufacturing a multilayer printed wiring board, comprising a step of solidifying the insulating resin to fix regions of the insulating base material where the conductive resin is not provided. 15. The method for manufacturing a multilayer printed wiring board according to claim 8, wherein the conductive resin contains tens of percent of metal powder as a conductive material.
A method for manufacturing a multilayer printed wiring board, comprising a synthetic resin exhibiting conductivity in a solidified state. 16. The method for manufacturing a multilayer printed wiring board according to claim 12, wherein the insulating resin is used as a filler and has a particle size distribution within a predetermined range. A method of manufacturing a multilayer printed wiring board, characterized by being a synthetic resin containing a filler and a heat latent curing material. 17. The method for manufacturing a multilayer printed wiring board according to claim 8, wherein the conductive material contains tens of percent of metal powder as a conductive material.
A method for manufacturing a multilayer printed wiring board, comprising a synthetic resin exhibiting conductivity in a solidified state. 18. The method for manufacturing a multilayer printed wiring board according to claim 8, wherein the conductive material is an alloy, and the step of embedding the through holes with the conductive material includes heating and melting the alloy. Into the through hole,
A method of manufacturing a multilayer printed wiring board, wherein the method is performed by cooling.