JP2002368364A - Printed wiring board and manufacturing method thereof - Google Patents

Abstract

[PROBLEMS] A print that can improve the moisture resistance of the entire printed wiring board, has excellent connection reliability and repair resistance, and has improved mechanical strength such as bending rigidity of an electrically insulating base material. Provided is a wiring board and a method for manufacturing the same. A through hole formed in a thickness direction of an electrically insulating base material is filled with a conductive material containing a conductive filler, and a predetermined pattern is formed on both surfaces of the electrically insulating base material. In a printed wiring board in which wiring layers 204, 206, and 208 are electrically connected by the conductor 205, the electrically insulating base material 201 is made of glass cloth or glass nonwoven fabric impregnated with a thermosetting epoxy resin mixed with fine particles. The conductive filler contained in the conductor has an average particle diameter larger than the average particle diameter of the fine particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board which is suitable for high-density mounting of various electronic devices having a high function, and has excellent bending rigidity or moisture absorption properties and is suitable for repair resistance, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as electronic equipment has become smaller, thinner, lighter, and more sophisticated, various electronic parts constituting the electronic equipment have become smaller and thinner, and these electronic parts have been mounted. Various technical developments that enable high-density mounting of printed wiring boards are also actively pursued.

In particular, with the recent rapid development of mounting technology, a circuit having a multilayer wiring structure capable of directly mounting a bare chip of a semiconductor device such as an LSI on a printed wiring board at a high density and corresponding to a high-speed signal processing circuit. There is a strong demand that substrates be supplied at low cost. In such a multilayer wiring circuit board, it is important to have high electrical connection reliability and excellent high-frequency characteristics between wiring patterns of a plurality of layers formed at a fine wiring pitch, and a high level with a semiconductor bare chip. Connection reliability is required.

To solve this problem, an interstitial via hole (also referred to as IVH) is filled with a conductor instead of the copper-plated conductor on the inner wall of the through hole, which has been the mainstream of interlayer connection in a conventional multilayer wiring board. In addition to improving connection reliability, IV
There is a resin multilayer wiring board having an all-layer IVH structure capable of forming H and realizing miniaturization of the board size and high-density mounting (JP-A-6-268345). 12A to 12G show a method for manufacturing the printed wiring board. First, FIG. 12A
As shown in FIG. 5, a release film 40 made of polyester or the like is provided on both sides of a porous substrate 402 which is an aramid epoxy prepreg obtained by impregnating a thermosetting epoxy resin into an aramid nonwoven fabric.
Laminate 1 Next, as shown in FIG. 12B, through holes 403 are formed at predetermined locations on the porous base material 402 by a laser processing method. Next, as shown in FIG. 12C, the conductive paste 404 is filled in the through holes 403. As a filling method, a porous substrate 402 having through holes 403 is placed on a table of a screen printing machine, and a conductive paste 404 is directly printed on the release film 401. At this time, the release film 401 on the printing surface plays a role of a print mask and a role of preventing contamination of the surface of the porous substrate 402. Next, the release film 40 is removed from both sides of the porous substrate 402.
1 is peeled off. Next, a metal foil 405 such as a copper foil is attached to both surfaces of the porous substrate 402. By heating and pressing in this state, as shown in FIG.
Is compressed and its thickness is reduced. At this time, the through hole 40
3, the binder component in the conductive paste is extruded at that time, and the bonding between the conductive components and between the conductive component and the metal foil 405 is strengthened. Densified and electrical connection between layers is obtained. Then, the porous substrate 402
Thermosetting resin and conductive paste 40 as constituents of
4 cures. Then, as shown in FIG.
05 is selectively etched into a predetermined pattern to complete a double-sided wiring board. Further, as shown in FIG. 12F, a porous base material 406 on which a conductive paste 408 is printed and a metal foil 407 are attached to both sides of the double-sided wiring board, and after heating and pressing, as shown in FIG. 12G. By selectively etching the metal foil 407 into a predetermined pattern, a multilayer wiring board is completed.

[0005] A resin multilayer substrate formed by using these circuit-forming substrates has been used in many electronic devices, taking advantage of its low expansion coefficient, low dielectric constant, and light weight.

[0006]

However, in the above-mentioned resin multilayer wiring board having the all-layer IVH structure, at present, the main constituent material is an aramid nonwoven fabric as a core material as described above, The composition of the material is such that the epoxy resin and the aramid nonwoven fabric fibers are homogeneously mixed. The electrically insulating substrate having an aramid nonwoven fabric as a core has a thermal expansion coefficient (also referred to as CTE) in the thickness direction of 100 pp.
m / ° C., which is significantly different from the CTE (about 17 ppm / ° C.) of the inner via conductor forming the all-layer IVH structure.

[0007] Therefore, under the severe use environment of electronic equipment which causes a rapid temperature change, a slight deterioration of the characteristics is observed, so that a more reliable printed wiring board has been desired.

[0008] The present invention is to solve the above problems,
Provided is a printed wiring board having excellent connection reliability and repair resistance by improving the moisture resistance of the entire printed wiring board, and also having improved mechanical strength such as bending rigidity of an electrically insulating base material, and a method of manufacturing the same. Is the first purpose.

A second object of the present invention is to provide, in addition to the first object, a thermal expansion coefficient (CTE) of the entire insulating substrate.
It is an object of the present invention to provide a printed wiring board having improved adhesiveness between the wiring pattern and the insulating substrate and improved connection reliability with the inner via conductor by reducing the size of the printed wiring board.

[0010]

According to a first aspect of the present invention, there is provided a printed wiring board comprising a conductive filler containing a conductive filler in a through hole formed in a thickness direction of an electrically insulating substrate. Body is filled, a printed wiring board in which a wiring layer formed in a predetermined pattern on both surfaces of the electrically insulating substrate is electrically connected by the conductor,
The electrically insulating substrate is formed of a substrate impregnated with a thermosetting epoxy resin obtained by mixing fine particles into glass cloth or glass nonwoven fabric, and the average particle size of the conductive filler included in the conductor is The fine particles are larger than the average particle size.

Next, a second printed wiring board according to the present invention includes an inner wiring board having at least two first wiring patterns connected by a first inner via conductor;
A second inner via conductor provided with conductivity by compressing glass epoxy resin as an insulating base material on both sides of the inner wiring board and a second wiring disposed on the outermost surface of the insulating base material An outer wiring board provided with a pattern, wherein the first inner wiring pattern on the surface of the inner wiring board and the second wiring pattern of the outer wiring board are electrically connected by the second inner via conductor. It is characterized by having been done.

Next, the first production method of the present invention is to release molds on both surfaces of an electrically insulating substrate made of a prepreg in which a glass cloth or a non-woven glass fabric is impregnated with a thermosetting epoxy resin mixed with fine particles. A through-hole is provided after covering the porous film, and the through-hole is filled with a conductor containing a conductive filler having an average particle diameter larger than the average particle diameter of the fine particles,
After peeling off the release film, a metal foil is laminated on both sides of the electrically insulating substrate, and the electrically insulating substrate on which the metal foil is laminated is heated and pressed to compress the electrically insulating substrate. A material and the metal foil are adhered, the metal foils are electrically connected to each other, and the metal foil is formed in a predetermined pattern.

Next, the second manufacturing method of the present invention is the first manufacturing method.
A conductive paste for forming a second inner via conductor in a through hole at an arbitrary location is filled on both surfaces of an inner wiring substrate having at least two layers of first wiring patterns connected by inner via conductors The glass epoxy resin insulating substrate in the prepreg state is disposed, and further, copper foil is disposed outside each of the two glass epoxy resin insulating substrates, and the inner layer wiring board and the prepreg state are disposed from outside the two copper foils. By pressing and heating the glass epoxy resin insulating substrate, a wiring pattern protruding from both sides of the inner layer wiring substrate is pressed into the inside of the glass epoxy resin insulating substrate in the prepreg state, and at the same time, the glass epoxy resin insulating substrate is pressed. The conductive paste provided on the substrate is compressed to form the outermost copper foil and the first layer of the inner layer wiring substrate. After the wiring patterns are electrically connected, characterized in that the copper foil is selectively etched to form a by the second wiring pattern and the outer layer wiring substrate.

[0014]

According to the first printed wiring board of the present invention, the moisture resistance of the entire printed wiring board is improved, whereby the connection reliability and the repair resistance are excellent, and the electric insulating base material is used. A printed wiring board having improved mechanical strength such as bending rigidity can be provided. Also, when an inorganic filler is mixed with the epoxy resin constituting the electrically insulating base material, the melt viscosity of the epoxy resin increases, and the resin flow generated at the interface between the electrically insulating base material and the metal foil during heating and pressing is suppressed. By preventing the epoxy resin from entering the interface between the metal foil and the conductor, the conductor is sufficiently compressed, and stable connection reliability is obtained.

If the average particle size of the inorganic filler is smaller than the average particle size of the conductive filler, the conductive filler is prevented from diffusing during heating and pressurization, and the conductor is sufficiently compressed. , And stable connection reliability can be obtained. The average particle size of the inorganic filler is preferably 10 to 50% of the average particle size of the conductive filler.

As the conductive filler, metal powder such as gold, silver, copper, and aluminum can be used. When the via hole diameter is about 50 μm, the average particle diameter of the conductive filler is preferably about 5 μm. When the via hole diameter is about 30 μm, the average particle diameter of the conductive filler is about 1 to 3 μm.
m is preferable.

The inorganic filler is SiO ₂ , Ti
When at least one selected from the group consisting of O ₂ , Al ₂ O ₃ , MgO, SiC, and AlN powder, a printed wiring board with further improved mechanical strength such as bending strength can be obtained.

The amount of the inorganic filler added is 25 to 4
When it is 5 vol.%, The melt viscosity can be maintained and the conductor can be sufficiently compressed. If the amount of the inorganic filler is less than 25 vol.%, Sufficient melt viscosity cannot be obtained, causing excessive resin flow. If it exceeds 45 vol.%, The fluidity of the epoxy resin deteriorates, and the epoxy resin becomes insufficient. Compression cannot be applied, and the adhesion decreases. The amount of the inorganic filler added is 35 to 40 vol. %.

If the thickness of the electrically insulating base material is smaller than the diameter of the through hole formed in the thickness direction of the electrically insulating base material, when the through hole is formed by using a laser processing machine or the like. Can be suppressed, and a thin and lightweight printed wiring board can be provided while maintaining rigidity. Note that the conductor is more likely to be compressed as the thickness of the electrically insulating substrate is smaller (the conductor is thicker by the thickness of the release film, so the compression ratio is higher). The thickness of the electrically insulating substrate is preferably 50 to 100 μm with respect to the diameter of 100 to 200 μm.

When voids are contained in the electrically insulating base material in the prepreg state, the electrically insulating base material is compressed by the amount of the voids during heating and pressurization, and the conductor is sufficiently compressed, so that the conductor is stabilized. The connection resistance is obtained.

Further, the coefficient of thermal expansion (CTE) in the thickness direction of the conductor filled in the through hole formed in the thickness direction of the electrically insulating substrate is determined by the coefficient of thermal expansion in the thickness direction of the electrically insulating substrate. , The strain caused by the CTE gap is suppressed even in an environment where a rapid temperature change occurs,
Stable connection reliability is obtained. The CTE in the thickness direction of the conductor is preferably equal to the CTE in the thickness direction of the electrically insulating base material.

Further, a multilayer printed wiring board obtained by laminating a plurality of printed wiring boards of the present invention can be provided. Thereby, a multilayer printed wiring board having highly reliable via hole connection can be provided.

In the multilayer printed wiring board of the present invention, if the thickness of the conductor filled in the through hole formed in the thickness direction of the electrically insulating substrate is substantially equal, excellent impedance characteristics can be obtained. Thus, it is possible to provide a printed wiring board suitable for a high-frequency circuit.

Further, when the conductor is a conductive paste,
When the conductive paste in the through hole is compressed, the resin component in the conductive paste is discharged from the through hole, and the conductive component in the conductive paste is densified, enabling highly reliable via hole connection become.

When the through holes are formed by a laser beam machine, the formation of the through holes having a fine diameter corresponding to the miniaturization of the wiring pattern can be performed easily and at a high speed.

Next, according to the first manufacturing method of the present invention, excellent in moisture resistance, connection reliability, or repair resistance,
Further, it is possible to provide a double-sided printed wiring board having improved mechanical strength such as bending rigidity of the electrically insulating substrate.

Further, when the thickness of the electrically insulating base material is reduced before and after heating and pressing, the conductor can be sufficiently compressed. In order to suppress the resin flow, it is preferable that the thickness of the electrically insulating base material is reduced by 10 to 15% before and after heating and pressing.

When the thickness of the conductor filled in the through hole formed in the thickness direction of the electrically insulating base material is reduced before and after heating and pressing, the conductor component in the conductor is reduced by sufficient compression. Dense and highly reliable via hole connection becomes possible. In addition, the thickness of the conductor is 30 to
Preferably, it is 40% thinner.

When the thickness of the center of the electrically insulating substrate after heating and pressing is substantially equal to that of the periphery, the entire electrically insulating substrate is uniformly compressed at the time of heating and pressing, thereby suppressing variation in connection resistance. be able to.

An electric insulating base material made of a prepreg obtained by impregnating a thermosetting epoxy resin into a glass cloth or a non-woven glass fabric filled with a conductor and a metal foil are attached to both sides of the double-sided printed wiring board. A step of burying the wiring layer of the double-sided printed wiring board in a resin layer on the surface of the electrically insulating base material by heating and compressing to make the thickness of all conductors substantially equal; Having a step of forming a predetermined pattern,
A thin, high-rigidity, small-sized multilayer printed wiring board having excellent reliability and capable of forming a dense wiring pattern on which ultra-miniaturized electronic components and the like can be mounted at a high density can be obtained.

Further, an electrically insulating base material made of a prepreg obtained by impregnating a thermosetting epoxy resin into a glass cloth or a non-woven glass fabric filled with a conductor is collectively provided between the plurality of double-sided printed wiring boards. A step of burying the wiring layer of the double-sided printed wiring board in a resin layer on the surface of the electrically insulating base material by applying, compressing by heating and pressing, and making the thickness of all conductors substantially equal. This makes it possible to obtain a multilayer printed wiring board having excellent reliability and capable of forming a dense wiring pattern on which ultra-miniaturized electronic components and the like can be mounted at a high density with a reduced number of steps and at low cost.

According to the second printed wiring board of the present invention, a glass epoxy resin board having high mechanical strength and moisture resistance is arranged as an outer wiring board, so that it is excellent in high bending strength and moisture resistance. Thus, a composite printed wiring board can be obtained.

It is preferable to use an aramid nonwoven fabric impregnated with a thermosetting epoxy resin as the insulating substrate as the inner layer wiring substrate, so that the first inner layer having a fine diameter can be formed at an arbitrary position on the insulating substrate. Since a via conductor can be provided and an all-layer IVH structure can be obtained, a printed wiring board on which high-density wiring is formed can be obtained.

Epoxy resin impregnated into glass fiber as the outer wiring board is made of SiO ₂ , TiO ₂ , Al.
It is preferable that at least one selected from inorganic fillers such as ₂ O ₃ , MgO, SiC or AlN powder is mixed in a range of 30% by weight to 70% by weight, so that the bending strength can be further improved and the compressibility can be improved. An excellent printed wiring board can be obtained.

Next, according to the second manufacturing method of the present invention, it is possible to provide a composite printed wiring board having high bending strength and excellent moisture resistance.

[0036]

Next, embodiments of the present invention will be described more specifically with reference to the drawings.

(Embodiment 1) FIGS. 1A to 1F are process sectional views showing a method for manufacturing a double-sided wiring board according to a first embodiment of the present invention.

First, as shown in FIG. 1A, an electrically insulating substrate which is a glass epoxy prepreg impregnated with a thermosetting epoxy resin in which glass cloth is mixed with 40 vol.% Of SiC fine particles having an average particle diameter of 2 μm. A release film 101 made of polyester or the like was laminated on both sides of the substrate 102.
Lamination was performed at a temperature of about 120 ° C. As a result, the resin layer on the surface of the electrically insulating substrate 102 was slightly melted, and the release film 101 could be attached.
In this example, a glass epoxy prepreg having a thickness of 100 μm of glass cloth, a thickness of 15 μm of a resin layer on the surface, and a thickness of 130 μm of the substrate was used as the electrically insulating substrate. FIG. 5 is a relationship diagram showing the dependency between the thickness of the resin layer of the base material of the printed wiring board and the initial resistance value. Since the initial resistance value decreases as the thickness of the resin layer of the base material decreases, a base material having a resin layer thickness of 130 μm was used in this example. Further, polyethylene terephthalate (PET) having a thickness of 19 μm was used for the release film. In addition, it is also possible to use a glass nonwoven fabric instead of a glass cloth and use an electrically insulating substrate having a resin layer formed on the surface.

As fine particles, inorganic fillers such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO
And AlN. The organic filler can include benzoguanamine, polyamide, polyimide, melamine resin, epoxy resin, and the like, and may be mixed with an inorganic filler and an organic filler.

Next, as shown in FIG. 1B, through holes 10 are formed in predetermined portions of the electrically insulating base material 102 by a laser processing method.
3 was formed. The through hole formed by the laser processing machine had a hole diameter of about 100 μm. The glass epoxy prepreg has 10 vol. % Included
The pore diameter was 3 μm.

Next, as shown in FIG. 1C, the conductive paste 104 was filled in the through holes 103. As a filling method, the conductive paste 104 was directly printed on the release film 101 by a screen printing machine to be filled. At this time, the resin component in the conductive paste 104 in the through-hole 103 is sucked by vacuum suction from a side opposite to the printing surface through a porous sheet such as Japanese paper, and the ratio of the conductor component is increased by increasing the ratio of the conductor component. Could be more densely packed. Further, the release film 101 plays a role of a print mask and a role of preventing contamination of the surface of the electrically insulating base material 102. The average particle size of the conductive filler in the conductive paste was 5 μm, larger than the diameter of the pores, and larger than the particle size of the fine particles.

Next, as shown in FIG. 1D, the release film 101 is peeled off from both sides of the electrically insulating substrate 102, and a metal foil 105 such as a copper foil is laminated on both sides of the electrically insulating substrate 102, and heated. Pressurized. The heating and pressurization was performed by a vacuum press. The conditions were as follows: temperature: 200 ° C., pressure: 4.9 MPa, degree of vacuum: 5.33 × 10 ³ Pa (40 Torr), processing time: 1 hour.

By heating and pressurizing under these conditions, FIG.
As shown in E, the electrically insulating substrate 102 was compressed, and its thickness was reduced to 118 μm at the center and 116 μm at the periphery, and the difference between the thickness at the center and the periphery was about 2%. The overall compression was about 10%. At that time, the conductive paste 104 in the through-hole 103 is also compressed, but at that time, the binder component in the conductive paste is extruded, and the bonding between the conductive components and between the conductive component and the metal foil 105 is strengthened. The conductive material inside was densified. The compression ratio of the conductor at this time was (168−117) × 100/168 = 30.4%. Then, the thermosetting resin and the conductive paste 104, which are the components of the electrically insulating base material 102, are heated at a temperature of 200.
° C, pressure: 4.9MPa, degree of vacuum: 5.33 × 10 ³ Pa (40Tor
The composition was cured by treating for 1 hour in r).

Finally, as shown in FIG. 1F, the metal foil 105
Is selectively etched into a predetermined pattern,
Electrical connection between the wiring layers 106 on the front and back of the electrically insulating base material 102 was obtained, and the double-sided wiring board was completed.

In this example, the average particle size of the conductive powder contained in the conductive paste was 5 μm, and the average particle size of the inorganic filler was 40% of the average particle size of the conductive powder. The CTE in the thickness direction of the conductor was about 30 ppm / ° C., the CTE in the thickness direction of the electrically insulating substrate was about 20 ppm / ° C., and the CTE of the conductor was larger than that of the electrically insulating substrate. .

By using a filler larger than the average particle size of the fine particles, the fine particles act as a shield in the resin layer on the surface of the electrically insulating base material during heating and pressurization, thereby preventing diffusion of the conductive filler. The conductor can be sufficiently compressed, stable connection reliability can be obtained, and excellent moisture absorption characteristics can be obtained. Therefore, it is possible to prevent the conductor and the wiring layer from peeling off due to a rapid temperature change even during solder dip or repair.

Further, 40 vol.% Of SiC as an inorganic filler was mixed in the epoxy resin constituting the electrically insulating base material, and the average particle size was 2 μm. 4A-C
FIG. 4 is a distribution diagram showing variation in resistance value of a printed wiring board. As shown in FIG.
In the case of l.%, the resistance values varied. On the other hand, as shown in FIG. 4B, when the amount of the filler was 30 vol.%, The distribution was large, but a slight variation was observed. And, as shown in FIG. 4C, when the filler amount was 40 vol.%, A more uniform distribution was observed.

The amount of the fine particles added is 25 to 45 vol.
In this case, since the melt viscosity can be maintained and the conductor can be sufficiently compressed, stable connection reliability can be obtained. If the addition amount of the fine particles is less than 25 vol.%, A sufficient melt viscosity cannot be obtained, and an excessive resin flow occurs in the resin layer on the surface of the electrically insulating base material, and the conductive filler contained in the conductor is Because of the diffusion, the pressure applied to the conductor also diffuses. Furthermore, the diffused conductive filler itself may cause migration and cause insulation failure. When the amount of the fine particles exceeds 45 vol.%,
The amount of epoxy resin that is sufficient to obtain sufficient adhesion is insufficient, and the fluidity of the epoxy resin is deteriorated, so that the conductor cannot be sufficiently compressed. The addition amount of the fine particles is 30 to 35 vol. % Is more desirable.

The printed wiring board of the present embodiment can provide a printed wiring board having improved mechanical strength such as bending stiffness of an electrically insulating base material, and excellent in connection reliability and moisture absorption properties.

Embodiment 2 FIGS. 2A to 2D show a second embodiment of the present invention.
FIG. 10 is a process cross-sectional view illustrating the method for manufacturing the double-sided wiring board in the Example of FIG.

First, as shown in FIG. 2A, a core substrate 201 manufactured in the same manner as in FIG. 1F of the first embodiment was prepared.

Next, as shown in FIG.
1 is superimposed on both sides of the electrically insulating substrate 202 in the step of FIG. 1C of the first embodiment.
03 were overlaid and heated and pressed. Heating and pressurization was performed by a vacuum hot press. Conditions are temperature: 200 ° C, pressure:
4.9 MPa, degree of vacuum: 5.33 × 10 ³ Pa (40 Torr), processing time: 1 hour.

The heating and pressurization causes the electrically insulating substrate 20
2 was compressed and thinned, and the wiring layer 204 was embedded in the electrically insulating substrate 202. At that time, the conductive paste 205 is also compressed, but at that time, the binder component in the conductive paste is extruded, and the bonding between the conductive components and between the conductive component and the metal foil 203 is strengthened. The conductive material was densified. Thereafter, the thermosetting resin and the conductive paste 205, which are the components of the electrically insulating base 202, were cured.

Next, as shown in FIG.
Is selectively etched into a predetermined pattern,
Electrical connection between the wiring layer 204 and the wiring layer 206 was obtained, and a four-layer wiring board was completed.

Finally, as shown in FIG. 2D, an electrically insulating base material 207 is superposed on both sides of the four-layer wiring board.
B, through the same steps as in FIG. 2C, electrical connection between the wiring layer 206 and the wiring layer 208 was obtained, and a six-layer wiring board was completed.

In the six-layer wiring board of this embodiment, since all layers are made of glass epoxy, it is possible to form a dense wiring pattern on which ultra-miniaturized electronic parts and the like can be mounted at a high density. A multilayer printed wiring board having excellent hygroscopicity or repairability can be provided.

(Embodiment 3) FIGS. 3A and 3B are process sectional views showing a method for manufacturing a double-sided wiring board according to a third embodiment of the present invention.

First, as shown in FIG. 3A, three core substrates 301 manufactured in the same manner as in FIG.
The electrically insulating substrate 302 in the step of FIG. 1C of the first embodiment.
Are prepared, and the electrically insulating base material 3 is placed between the core substrates 301.
02 were superimposed and heated and pressed. Heating and pressurization was performed by a vacuum hot press. Conditions are temperature: 200 ° C,
Pressure: 4.9 MPa, degree of vacuum: 5.33 × 10 ³ Pa (40 Torr),
Processing time: 1 hour.

By this heating and pressing, as shown in FIG. 3B, the electrically insulating substrate 302 was compressed and thinned, and the wiring layer 303 was embedded in the electrically insulating substrate 302. At that time, the conductive paste 304 is also compressed, but at that time, the binder component in the conductive paste is extruded,
Bonding between the conductive components and between the conductive component and the wiring layer 303 was strengthened, and the conductive material in the conductive paste 304 was densified. Thereafter, the thermosetting resin and the conductive paste 304, which are the components of the electrically insulating base material 302, are cured by the heating and pressurization, and are electrically connected between the wiring layers 303, thereby completing the six-layer wiring board. .

The six-layer wiring board of the present embodiment has a dense wiring pattern in which all layers are made of glass epoxy and laminated at a time so that ultra-miniaturized electronic parts can be mounted at a high density. And a multilayer printed wiring board excellent in rigidity, hygroscopicity or repairability can be provided inexpensively with fewer steps.

(Embodiment 4) FIG. 6 shows a printed wiring board according to Embodiment 4 of the present invention. The outer wiring board 6 using the glass epoxy resin as the insulating base material 5 was produced in the same manner as in Example 1. Then, the first inner via conductor 1a and the first
The first inner layer wiring board 4 is formed on both surfaces of an inner layer wiring board 4 having an all-layer IVH structure having a three-layer structure using an aramid epoxy resin having the wiring pattern 2a formed thereon as an insulating base material 3 by a second inner via conductor 1b. An outer wiring board 6 having an insulating base material 5 made of glass epoxy resin having an outermost second wiring pattern 2b connected to the wiring pattern 2a is disposed. The second inner via conductor 1b is
The conductive paste filled in the through-hole was formed by compression when the and the outer wiring board 6 were laminated and integrally formed.
The second inner via conductor 1b thus formed
Had sufficient conductivity.

(Embodiment 5) Next, FIG. 7 shows Embodiment 5 of the present invention. The difference from Embodiment 4 is that, as shown in FIG. 3 is a double-sided wiring board, and the other configuration is the same as that of the first embodiment.

Embodiment 6 Next, a method for manufacturing a printed wiring board according to Embodiment 6 of the present invention will be described with reference to FIGS.
Using C, the same parts as those in FIG.

As shown in FIG. 8A, second inner via conductors 1b are formed on both surfaces of an inner wiring board 4 having an all-layer IVH structure in which first wiring patterns 2a of each layer are connected by first inner via conductors 1a. An insulating base material 5 made of a glass epoxy resin in a prepreg state filled with a conductive paste 7 containing a conductive powder such as silver or copper as a main component by printing or the like is formed on both sides thereof. Copper foil 8
Place.

Thereafter, as shown in FIG. 8B, the whole is compressed and laminated by pressing and heating from both sides using a press machine such as a mold. By doing so, the first wiring pattern 2a formed on the outermost layer of the inner wiring board 4 is pressed into the surface layer of the glass epoxy resin substrate 5 which was in a prepreg state before compression, and The conductive paste 7 provided on the epoxy resin insulating base material 5 is compressed to generate conductivity, and becomes the second inner via conductor 1b to electrically connect the first wiring pattern 2a and the copper foil 8. I do. At this time, the copper foil 8 is firmly bonded by the epoxy resin layer flowing on the surface of the insulating base material 5.

Next, as shown in FIG. 8C, the outermost copper foil 8 adhered to both sides is selectively patterned by a normal photolithography method to form a second wiring pattern 2b, thereby forming a first wiring pattern 2b. A composite printed wiring board having a multilayer structure in which the wiring pattern 2a and the second wiring pattern 2b are connected to each other by the first inner via conductor 1a and the second inner via conductor 1b can be obtained.

FIG. 9A is a partially enlarged view showing a state where the insulating base material 5 and the copper foil 8 are laminated on the inner wiring board 4 in the manufacturing method shown in FIG. 8A. The insulating base material 5 made of a glass epoxy resin in a prepreg state is in a state where the glass fibers 5a are aggregated on the inner layer of the insulating base material and the epoxy resin 5b stays on the surface of the insulating base material 5.

Therefore, after arranging the insulating base material 5, the inner wiring board 4 and the copper foil 8 as shown in the figure, by applying heat and pressure from both sides, the wiring pattern of the inner wiring board 4 as shown in FIG. 2a is pressed into and embedded in the epoxy resin 5b staying on the surface of the insulating base material 5.

At the same time, the thickness of the conductive paste 7 filling the through holes of the insulating base material 5 starts at t _1.
Is compressed to a thickness of t ₂ to form a low-resistance second inner via conductor 1 b and electrically connect the first wiring pattern 2 a of the inner wiring board 4 to the copper foil 8. It is possible to do.

Next, FIG. 10 shows SiO ₂ , Ti in glass epoxy resin as the insulating base material shown in FIGS. 9A and 9B.
Outer layer wiring board in the case where a mixture of at least one of inorganic fillers 9 composed of O ₂ , Al ₂ O ₃ , MgO, SiC, AlN powder and the like is added in the range of 30% by weight to 70% by weight. 10 is shown. The addition of the inorganic filler 9 increases the viscosity of the epoxy resin and prevents the electrically insulating epoxy resin from entering the interface between the first wiring pattern 2a or the copper foil 8 and the conductive paste. Connection reliability can be improved. Further, the mechanical strength of the printed wiring board can be improved. In the above, the conductive paste is heated and pressurized to form the second wiring pattern 1b.

Further, by mixing the inorganic filler, the CTE in the thickness direction of the insulating base material can be reduced to 20 ppm to 30 ppm.
pm, it is close to the CTE (about 17 ppm) of the inner via conductor, the connection reliability between the wiring pattern and the inner via conductor can be improved, and the thermal expansion coefficient in the surface direction of the printed wiring board is also small. Therefore, when a semiconductor chip is mounted, the connection reliability can be improved.

FIG. 11 shows the results of measuring the bending stiffness of the inner wiring board 4, the outer wiring board 6, and the outer wiring board 10 to which the inorganic filler is added, which constitute the printed wiring board according to the present invention. As described above, the outer wiring board 6 made of glass epoxy resin has a higher bending strength than the inner wiring board 4 made of aramid epoxy resin, and the outer wiring board 1 added with an inorganic filler.
It can be seen that 0 has more excellent bending strength.

Therefore, the printed wiring board according to the present invention, in which the outer wiring board 6 or 10 made of glass epoxy resin is disposed on both side surfaces of the inner wiring board 4 made of aramid epoxy resin, has the mounting reliability of various electronic components and the repair of components. It is possible to provide excellent properties such as heat resistance and moisture resistance.

If the amount of the inorganic filler 9 is less than 30% by weight, further improvement in mechanical strength cannot be expected. If the amount exceeds 70% by weight, the flowability of the epoxy resin deteriorates, and the impregnation property with respect to the glass fiber becomes poor. This makes it difficult to obtain a homogeneous glass epoxy resin insulating substrate.

[0075]

As is apparent from the above description, the present invention provides a printed wiring board in which the electrically insulating substrate is formed of a glass epoxy resin board, and by improving the moisture resistance of the entire printed wiring board. Connection reliability,
It is possible to provide a printed wiring board excellent in repair resistance and improved in mechanical strength such as bending rigidity of the electrically insulating base material.

Further, the present invention provides a printed wiring board in which the thermal expansion coefficient (CTE) of the entire insulating board is reduced, thereby improving the adhesiveness between the wiring pattern and the insulating board and the connection reliability with the inner via conductor. it can.

[Brief description of the drawings]

FIGS. 1A to 1F are process cross-sectional views illustrating a method for manufacturing a printed wiring board according to a first embodiment of the present invention.

FIGS. 2A to 2D are process cross-sectional views illustrating a method for manufacturing a printed wiring board according to a second embodiment of the present invention.

FIGS. 3A and 3B are process cross-sectional views illustrating a method of manufacturing a printed wiring board according to a third embodiment of the present invention.

FIGS. 4A to 4C are distribution diagrams showing variations in the resistance value of the printed wiring board in the first embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the thickness of the resin layer of the printed wiring board and the initial resistance value according to the first embodiment of the present invention.

FIG. 6 is a sectional view showing the structure of a printed wiring board according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing the structure of a printed wiring board according to a fifth embodiment of the present invention.

FIGS. 8A to 8C are cross-sectional views illustrating a method of manufacturing a printed wiring board according to a sixth embodiment of the present invention.

9A and 9B are enlarged views of a part of the process cross-sectional views shown in FIGS. 8A and 8B.

10 is a partially enlarged cross-sectional view illustrating a case where an inorganic filler is mixed into the insulating base material illustrated in FIG. 9B.

FIG. 11 is a mechanical strength characteristic diagram of an inner wiring board and an outer wiring board constituting a printed wiring board according to a sixth embodiment of the present invention.

12A to 12G are process cross-sectional views illustrating a conventional method for manufacturing a multilayer wiring board.

[Explanation of symbols]

 1a First inner via conductor 1b Second inner via conductor 2a First wiring pattern 2b Second wiring pattern 4 Inner layer wiring board 5 Glass epoxy resin board (insulating base material) 6,10 Outer layer wiring board 101 Release film Reference Signs List 102 electric insulating base material 103 through hole 104 conductive paste 105 metal foil 106 wiring layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 3/46 H05K 3/46 GNT (72) Inventor Satoshi Nakamura 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Inside Electric Industrial Co., Ltd. (72) Inventor Yasuhiro Nakaya 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Inventor Nishiyama Tosaku 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. CD32 GG03 GG05 GG12 GG20 5E339 AB02 AD05 BD03 BD06 BE13 5E346 AA06 AA12 AA15 AA22 AA32 AA43 AA51 CC04 CC08 DD32 EE06 EE07 EE09 EE13 FF18 GG15 GG19 GG22 GG28 HH08 HH13 HH18

Claims (22)

[Claims] 1. A wiring layer formed by filling a conductor including a conductive filler into a through hole formed in a thickness direction of an electrically insulating substrate, and forming a predetermined pattern on both surfaces of the electrically insulating substrate. Wherein the electrically insulating substrate is a material including a substrate impregnated with a thermosetting epoxy resin in which fine particles are mixed into glass cloth or glass nonwoven fabric. A printed wiring board formed, wherein the average particle diameter of the conductive filler contained in the conductor is larger than the average particle diameter of the fine particles. 2. The method according to claim 1, wherein the fine particles are SiO ₂ , TiO ₂ , Al ₂
O _3, MgO, printed wiring board according to claim 1 is at least one inorganic filler selected from SiC and AlN powder. 3. A thermal expansion coefficient in a thickness direction of a conductor filled in a through hole formed in a thickness direction of the electrically insulating substrate is larger than a thermal expansion coefficient in a thickness direction of the electrically insulating substrate. The printed wiring board according to claim 1. 4. The amount of the fine particles added is 25 to 50 vol.%.
The printed wiring board according to claim 1, wherein 5. The printed wiring board according to claim 1, wherein the thickness of the electrically insulating substrate is smaller than the diameter of a through hole formed in the thickness direction of the electrically insulating substrate. 6. The printed wiring board according to claim 1, wherein the electrically insulating base material in the prepreg state contains voids. 7. The printed wiring board according to claim 1, wherein the number of the printed wiring board is one. 8. The printed wiring board according to claim 1, wherein the printed wiring board is a multilayer printed wiring board in which a plurality of printed wiring boards are stacked. 9. The printed wiring board according to claim 8, wherein the thickness of the conductor filled in the through hole formed in the thickness direction of the electrically insulating base material of the multilayer printed wiring board is substantially equal. 10. An inner layer provided with conductivity by compression, wherein the electrically insulating base material is a base material impregnated with a thermosetting epoxy resin in which fine particles are mixed in glass cloth or glass nonwoven fabric, and is used as an outer wiring board. A wiring board having at least two layers of wiring patterns electrically connected by via conductors is used as an inner wiring board, and the wiring pattern of the outer wiring board and the wiring pattern of the inner wiring board are electrically connected. Items 1 to 9
The printed wiring board according to any one of the above. 11. The printed wiring board according to claim 10, wherein the inner wiring board is an insulating base material in which an aramid nonwoven fabric is impregnated with a thermosetting epoxy resin. 12. The printed wiring board according to claim 10, wherein a plurality of outer wiring boards are formed on at least one surface. 13. A method for manufacturing a printed wiring board according to claim 1, wherein a prepreg obtained by impregnating a glass cloth or a glass nonwoven fabric with a thermosetting epoxy resin mixed with fine particles. A through hole is provided after covering the release film on both sides of the electrically insulating base material, and the through hole is filled with a conductor containing a conductive filler having an average particle diameter larger than the average particle diameter of the fine particles, After peeling off the release film, a metal foil is laminated on both sides of the electrically insulating substrate, and the electrically insulating substrate on which the metal foil is laminated is heated and pressurized and compressed to thereby form the electrically insulating substrate. A method for manufacturing a printed wiring board, comprising: bonding a material to the metal foil; electrically connecting the metal foils; and forming the metal foil in a predetermined pattern. 14. The resin layer on the surface of the prepreg having a thickness of 5
The method for manufacturing a printed wiring board according to claim 13, wherein the thickness is not less than 25 µm and not more than 25 µm. 15. The method for producing a printed wiring board according to claim 12, wherein the electrically insulating base material in a prepreg state contains holes. 16. The method according to claim 13, wherein the diameter of the hole is smaller than the diameter of the conductive filler contained in the conductor. 17. The method for manufacturing a printed wiring board according to claim 13, wherein the thickness of the electrically insulating base material is reduced by heating and pressing. 18. The printed wiring according to claim 13, wherein the thickness of the conductor filled in the through hole formed in the thickness direction of the electrically insulating base material is reduced by heating and pressing. Substrate manufacturing method. 19. The method for manufacturing a printed wiring board according to claim 13, wherein the thickness of the central portion and the peripheral portion of the electrically insulating substrate after heating and pressing are substantially equal. 20. A thermosetting epoxy in which fine particles are mixed into a glass cloth or a glass nonwoven fabric filled with an electric conductor on both sides of a printed wiring board formed by the manufacturing method according to claim 13. The wiring layer of the printed wiring board is buried in the resin layer on the surface of the electric insulating base material by applying an electric insulating base material made of a prepreg impregnated with a resin and a metal foil and applying heat and pressure to compress. And a method for manufacturing a printed wiring board, wherein the metal foil is formed in a predetermined pattern. 21. Fine particles are mixed in a glass cloth or a glass nonwoven fabric filled with a conductor between a plurality of double-sided printed wiring boards formed by the manufacturing method according to claim 13. An electric insulating base material made of a prepreg impregnated with a thermosetting epoxy resin is collectively adhered, heated and pressed and compressed, so that a resin layer on the surface of the electric insulating base material is applied to the printed wiring board. A method of manufacturing a printed wiring board in which a wiring layer is embedded to make all conductors substantially equal in thickness. 22. The method for manufacturing a printed wiring board according to claim 10, wherein at least two of the printed wiring boards connected by the first inner via conductor are connected to each other.
Glass epoxy resin in a prepreg state in which a conductive paste for forming a second inner via conductor in a through hole at an arbitrary position is filled on both sides of a compressible inner wiring substrate having a first wiring pattern of layers An insulating substrate is disposed, and a copper foil is further disposed outside each of the two glass epoxy resin insulating substrates. The inner layer wiring substrate and the glass epoxy resin insulating substrate in a prepreg state are added from outside the two copper foils. By pressurizing and heating, the wiring pattern protrudingly provided on both surfaces of the inner layer wiring board is press-fitted into the glass epoxy resin insulating substrate in the prepreg state and at the same time the wiring pattern provided on the glass epoxy resin insulating substrate is provided. After compressing the conductive paste to electrically connect the outermost copper foil and the first wiring pattern of the inner wiring board Method for manufacturing a printed wiring board with the copper foil selectively etched to form a a second wiring pattern constituting the outer layer wiring substrate.