JP2003200535A - Prepreg, circuit substrate and method of manufacture thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg and a circuit substrate which realize characteristics such as low interstitial via hole (IVH) connection resistance, high connection stability and durability without depending upon the material quality, physical property, combination and the like of an insulating layer, and to provide a method of manufacture thereof. <P>SOLUTION: The prepreg 3 comprises a laminate of at least a first single layer 2 and at least a second single layer 1. The first single layer 2 is an insulating layer containing a resin, while the second single layer 1 is a layer having a hole part connected to both sides of the layer 1. In addition, at least one selected prepreg 3 to be used shows a difference from the other on both sides of the layer, with regard to the rate of hole area and the average hole diameter of the second single layer 1. Thus, it is possible to realize the circuit substrate with superb characteristics such as the low IVH connection resistance, high connection stability and durability. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg and a circuit board, and a method for manufacturing them.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and lighter and have higher performance, it has been strongly demanded to supply inexpensively a multi-layer circuit board on which semiconductor chips such as LSI can be mounted in high density in a wide range of consumer devices. Is requested. In response to these market demands, technological development is underway to replace resin multi-layer circuit boards, which can be supplied at a lower cost, with circuit boards suitable for high-density mounting, instead of the conventional mainstream ceramic multi-layer circuit boards. It is being appreciated. As such a resin multilayer circuit board, an interstitial via hole
There is known a circuit board having a structure of a stiff via hole (hereinafter referred to as IVH) (see, for example, Patent Document 1).

This all-layer IVH structure resin multilayer circuit board is a resin multilayer circuit board using a composite material of an aramid nonwoven fabric reinforcing material and an epoxy resin as an insulating layer. Also,
An IVH connection method has been realized in which arbitrary wiring pattern layers can be electrically connected at arbitrary positions through a conductive paste in all layers of a circuit board. Therefore, the circuit board is suitable for high-density mounting while being able to be supplied at a relatively low cost.

[0004]

[Patent Document 1] JP-A-6-268345

[0005]

In the above-mentioned prior art, it is necessary to use a prepreg in which an aramid nonwoven fabric reinforcing material is impregnated with an epoxy resin and has voids inside. In other words, it is a technology that can be realized only with a specific material. However, the market demand for circuit boards these days is not limited to those that allow high-density mounting, but also circuit boards with low permittivity suitable for high-speed transmission circuits, circuit boards that can be mounted at high density, and have high heat resistance. Have passed to. Therefore, it is required to realize a circuit board suitable for high-density mounting by using an arbitrary material having physical properties suitable for each demand.

Therefore, the present invention is not limited to the combination of materials used, and provides a prepreg and a circuit board which realize low interstitial via connection resistance and excellent connection stability, and a method for manufacturing them. With the goal.

[0007]

The prepreg of the present invention comprises:
It includes a laminated body of at least one first layer and at least one second layer, the first layer is an insulating layer containing a resin, and the second layer is provided on both sides of its own layer. At least one selected from the porosity and the average pore diameter of the second layer is a layer having continuous pores, and both sides of the self layer are different from each other.

Further, the circuit board of the present invention includes an insulating layer in which at least one first insulating layer and at least one second insulating layer are integrated, and a wiring pattern layer, which are integrated as described above. The wiring pattern layer is disposed on at least one surface of the insulating layer, the first insulating layer is a layer containing a resin, and the second insulating layer is connected to both surfaces of its own layer. A layer having a structure in which the resin contained in the first insulating layer flows into a layer having pores, and at least one selected from the porosity and the average pore diameter of the layer having pores is They differ from each other on both sides of the layer.

The method for producing a prepreg of the present invention comprises (i)
A step of forming a first layer which is an insulating layer containing a resin,
(Ii) forming a second layer laminated on at least one surface of the first layer to form a laminate of the first layer and the second layer, The second layer is a layer having a void portion connected to both surfaces of its own layer, and the second layer
At least one selected from the porosity and the average pore size of the layer is different from each other on both sides of the layer.

The circuit board manufacturing method of the present invention is
(I) a step of forming a first layer which is an insulating layer containing a resin, and (II) forming a second layer laminated on at least one surface of the first layer to form the first layer. Forming a laminate of layers and the second layer; (III) forming holes in the thickness direction of the laminate and filling the holes with a conductive paste; (IV) Pressing the laminate to compress it in the thickness direction, allowing the resin contained in the first layer to flow into the second layer, and compressing the conductive paste to form a conductor. After (II) and before (IV), (Z) arranging at least one selected from a metal foil and a wiring pattern on at least one surface of the laminate, The second layer is a layer having voids connected to both sides of its own layer,
At least one selected from the porosity and the average pore diameter of the second layer is different from each other on both sides of its own layer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The prepreg of the present invention includes a laminate of at least one first layer and at least one second layer, and the first layer is an insulating layer containing a resin. The second layer is a layer having pores connected to both surfaces of the own layer, and at least one selected from the porosity and the average pore diameter of the second layer is different from each other on both surfaces of the own layer. ing.

When this prepreg is heated and pressed,
The resin contained in the first layer is melted and flows into the pores of the second layer. Therefore, the prepreg has a high compressibility regardless of the material and type of the first layer. In addition, since the porosity and / or the average pore size of the second layer are different from each other on both sides of the self layer, the second layer may be formed depending on the melt viscosity characteristic of the resin contained in the first layer. The speed of inflow of the resin into the pores of
The amount of inflow can be controlled. Therefore, by using this prepreg, the conductive paste can be effectively compressed when the circuit board is formed, regardless of the material of the first layer to be the insulating layer. Therefore, it is possible to obtain a circuit board having low electrical connection resistance and excellent connection stability. The "open area ratio" refers to the ratio of the area of the above surface to the total area of the voids on the above surface. An optical microscope, an electron microscope or the like may be used to measure the open area ratio and the average pore diameter.

The first layer may be electrically insulating and may contain a resin which can flow into the second layer when the prepreg is heated and pressed. For example, a layer having a structure in which an insulating core material is impregnated with a resin, a resin sheet, or the like may be used. As the layer having the above structure, for example, a commercially available prepreg may be used. There is no particular limitation on the commercially available prepreg. For example, glass epoxy prepreg or aramid epoxy prepreg may be used. Examples of the resin sheet include epoxy resin, polyimide resin, bismaleimide triazine resin, polyphenylene ether resin, cyanate ester resin, polytetrafluoroethylene (PTF).
E) Resin or the like may be used. You may mix several different resins. You may laminate | stack a several different resin layer. Moreover, in the case of a resin sheet, an adhesive sheet can also be used.

The case where the adhesive sheet is used as the first layer will be described. The adhesive sheet is, for example, a film made of a thermoplastic resin such as polyimide, liquid crystal polymer, aramid, or PTFE, or a thermosetting resin,
A sheet containing a thermoplastic adhesive or a semi-cured thermosetting adhesive on both sides or one side thereof. The type of the adhesive can be arbitrarily selected depending on the combination of the metal used for the film and the wiring pattern layer, and is not particularly limited. However, in order for the adhesive to flow into the second layer when the prepreg is heated and pressed, it is necessary that the adhesive has fluidity during the process. For this reason,
When using a thermosetting adhesive, the adhesive may be in a semi-cured state. When a thermoplastic adhesive is used, the temperature of the step of introducing the adhesive may be set to the softening temperature of the adhesive or higher to fluidize the adhesive.

The adhesive is not particularly limited. For example, as the thermosetting adhesive, an epoxy-based adhesive, a polyimide-based adhesive, an acrylic adhesive, or the like may be used. As the thermoplastic adhesive, a polyamide-based adhesive, a polyphenylene ether (PPE) -based adhesive, or the like may be used. Also,
When a film made of a thermoplastic resin is used, since the film itself has adhesiveness at a temperature equal to or higher than the softening point of the film, the film itself can also serve as an adhesive layer.

The second layer has pores connected to both sides of its own layer. However, it is not necessary that all pores are connected to both sides of the own layer. Further, the structure does not necessarily have to be a hole shape, and may be a structure having voids such as woven cloth or nonwoven cloth. In this case, the material of the woven or non-woven fabric may be either an organic substance or an inorganic substance, as long as the void portion exists inside the second layer.

The difference in porosity between both surfaces of the second layer is, for example, in the range of 1% to 20%, preferably 2% to 15%. For example, an epoxy layer as the first layer, a second layer
In the case of a two-layer prepreg that uses an aramid layer as the layer, the porosity of the surface of the aramid layer in contact with the epoxy layer is preferably in the range of 7% to 10%, and 9% to
The range of 10% is more preferable. The open area ratio of the surface opposite to the aramid layer is preferably in the range of 10% to 13%, more preferably 11 to 12%.

The difference in average pore size on both sides of the second layer is
For example, in the range of 0.03 μm to 5 μm, 0.05
The range of μm to 2 μm is preferable. For example, in the case of the above two-layer prepreg, the average pore diameter of the surface of the aramid layer in contact with the epoxy layer is preferably 0.01 μm to 0.2 μm, more preferably 0.03 μm to 0.1 μm. preferable. The average pore diameter of the surface on the opposite side of the aramid layer is preferably 0.2 μm to 2 μm, and 0.2 μm.
The range of 0.5 μm is more preferable.

Further, the magnitude relation of the open area ratio on both surfaces of the second layer may be changed depending on the materials of the first layer and the second layer. For example, in the case of a prepreg consisting of a polyphenylene ether layer as the first layer and an aramid layer as the second layer, the porosity of the surface of the aramid layer in contact with the polyphenylene ether layer is It is preferably larger than the open area ratio of the other surface.
The same applies to the magnitude relationship of the average pore size.

Further, the second layer may be a porous layer. Since the porous layer has a high ability to absorb the molten resin, the compressibility of the prepreg can be further enhanced.

The material used for the porous layer is not particularly limited. For example, a porous sheet containing PTFE, polyimide, aramid, liquid crystal polymer, or the like may be used. In particular, the PTFE sheet or film has an average pore size of about submicron (0.1 μm) to several microns (9 μm).
Since it is commercially available (for example, Gore-Tex manufactured by Japan Gore-Tex Co., Ltd.), it is preferable that it is controlled to about μm). Further, since PTFE has a low dielectric constant, it is a particularly preferable material when manufacturing a circuit board used for a high frequency circuit.

Even when the second layer is a porous layer, it is necessary that at least one of the pores is connected to both sides of its own layer. That is, there must be at least one independent non-bubble-shaped hole.

The porosity of the second layer is, for example, 20% by volume.
˜80% by volume. Above all, 50% by volume to 7
The range of 0% by volume is preferable. In the above range, the compression rate of the prepreg becomes a value more suitable for forming the circuit board, and the electrical connection between the wiring pattern layers due to the compression of the conductive paste becomes better.

The prepreg of the present invention may have a plurality of first layers and second layers alternately laminated. When the prepreg is heated and pressurized, the first prepreg is placed against the plurality of second layers disposed inside the prepreg.
Since resin inflow occurs from the layer (1), the compressibility of the prepreg can be further enhanced.

In particular, when both outermost layers are composed of the second layer, both outermost layers may have different average pore sizes. Further, the porosities of both outermost layers may be different from each other. When heating and pressing the prepreg, the degree of compression on both sides of the prepreg will be different, the difference in the material when laminating another layer, and the hole diameter on both sides of the prepreg when a through hole is opened as a hole. It is possible to arbitrarily control the compression state of the prepreg according to the difference or the like.

The prepreg according to the present invention is the first
The resin contained in the first layer may be contained in the void portion of the second layer in contact with the layer. In such a prepreg, the resin contained in the first layer is partially inflowed to the second layer side, so that the bonding between the layers is good, and the prepreg is easily handled and punched. Can be done. In addition, when the prepreg is heated and pressed, the molten resin of the first layer can easily flow into the second layer.

The prepreg in the present invention is the first
The layer may contain a filler. For example, when a commercially available prepreg is used as the first layer, a filler is used as a resin for impregnating a woven fabric or a non-woven fabric as a reinforcing structural material.
You may use resin containing. As the first layer containing such a filler, there is, for example, a glass epoxy prepreg containing a filler in which a glass woven cloth is impregnated with an epoxy resin in which silica particles are dispersed. Also, when the resin sheet is used as the first layer, the resin may contain a filler.

As the filler, for example, an insulating filler such as silica, alumina or aluminum hydroxide may be used. The type of filler may be selected according to the characteristics required for the circuit board. For example, if aluminum hydroxide is used as the filler, it is possible to obtain an environment-friendly flame-retardant circuit board without containing a halogen substance necessary for flame-retardancy.

When the first layer contains a filler, the average pore diameter of the second layer is larger than that of the filler so that the filler particles do not get in the way when the molten resin flows into the second layer. Is also preferably small. It is more preferable that the average pore size of the second layer is equal to or smaller than the minimum particle size of the filler. At the time of heating and pressurizing the prepreg, the filler contained in the first layer hardly flows into the second layer, so that the prepreg can be compressed more efficiently.

The compression rate of the prepreg is, for example, in the range of 2% to 30%. By using such a prepreg, a circuit board having low connection resistance and excellent durability can be efficiently formed.

Here, the compression rate can be expressed by the following equation (1).

Compressibility (%) = ((T ₀ −T _L ) / T ₀ ) × 100 (1) where T ₀ : average thickness of prepreg before compression T _L : average thickness of prepreg after compression It is.

The compressibility of the prepreg can be controlled, for example, by changing the ratio of the total volume of the pores included in the second layer to the total volume of the prepreg. The total volume of the pores included in the second layer is, for example,
It can be controlled by setting the porosity of the second layer and the thickness of the second layer. This is because the total volume of the voids is proportional to “the porosity of the second layer × the volume of the second layer”.

The method for producing a prepreg of the present invention comprises (i)
A step of forming a first layer which is an insulating layer containing a resin,
(Ii) forming a second layer laminated on at least one surface of the first layer to form a laminate of the first layer and the second layer, The second layer is a layer having pores connected to both surfaces of the self layer, and at least one selected from the porosity and the average pore diameter of the second layer is different on both surfaces of the self layer. .

By adopting such a manufacturing method, the conductive paste is excellent in compressibility and the conductive paste is effectively compressed when forming the circuit board regardless of the material of the first layer to be the insulating layer. It is possible to obtain a prepreg capable of In addition,
The first layer and the second layer are the same as the first layer and the second layer in the prepreg of the present invention described above.

In the above manufacturing method, the above (ii) is
(Ii-a) applying a solution of the resin contained in the second layer onto the base material; (ii-b) gelling the resin contained in the second layer; and (ii) -C) a step of forming the second layer on the substrate by washing and drying the gelled resin, and (ii-d) the step of forming the second layer on at least one surface of the first layer. The step of laminating two layers may be included. It is possible to efficiently obtain a laminate of the second layer and the first layer in which at least one selected from the porosity and the average pore size is different from each other on both sides of the self layer.

The substrate is not particularly limited as long as it is in the form of a film. For example, polyethylene terephthalate (P
ET film and polyethylene naphthalate (PE
N) A film or the like may be used. A releasable film may be used later to facilitate separation of the base material and the second layer formed on the base material.

The resin contained in the second layer may be the above-mentioned resin used in the second layer of the prepreg of the present invention. For example, aramid or polyimide may be used.

When aramid is used, it is preferably m-aramid. Although p-aramid can be used, it is necessary to use sulfuric acid as a solvent to dissolve p-aramid. Therefore, m-aramid is superior in workability such as easier solvent replacement described later (m-aramid is N-methyl-2-pyrrolidone (NM
P), dissolved in an aprotic polar solvent such as dimethylformamide (DMF)).

When the solution of the resin contained in the second layer is applied onto the substrate, a known method such as roll coating, curtain coating, spray coating, kiss coating or the like may be used.

In order to gel the resin contained in the second layer, for example, a gelling agent may be added to the resin solution applied on the substrate in advance, or the solvent in the solution may be changed to another. It may be replaced with a solvent (wet coagulation method). As the other solvent to be replaced, a solvent that does not dissolve the resin contained in the second layer is preferable. For example, when m-aramid is used, it may be immersed in water or alcohol to replace the solvent.

For washing and drying the gelled resin, a generally known method may be used. For example, the washing may be performed with running water, and the drying may be performed with hot air.

The porosity of both surfaces of the second layer can be adjusted by adding additives to the resin solution applied on the substrate or adjusting the coating speed, the drying speed, and the temperature of each step. And the average pore size can be controlled. As the additive, lithium nitrate, polyvinylpyrrolidone, or the like can be used.

In the above manufacturing method, the above (i
i) comprises: (ii-A) applying a solution of a resin contained in the second layer on at least one surface of the first layer; and (ii-B) applying the solution to the second layer. Gelling a resin contained therein, and (ii-C) forming the second layer on at least one surface of the first layer by washing and drying the gelled resin. May be included. At least one selected from the porosity and the average pore size is different from each other on both sides of the second layer.
It is possible to efficiently obtain a layered product of the layer (1) and the first layer. The method of gelling the resin contained in the second layer, the resin contained in the second layer, and the like may be the same as those in the method of manufacturing the prepreg described above.

After the solution is applied to one surface of the first layer to form the laminate, the second layer formed on the substrate is formed on the other surface of the first layer. You may laminate further. Also, the reverse order can be performed.

The method of manufacturing a circuit board according to the present invention comprises: (I) a step of forming a first layer which is an insulating layer containing a resin;
I) forming a second layer laminated on at least one surface of the first layer to form a laminate of the first layer and the second layer, and (III) the above Forming a hole in the thickness direction of the laminate and filling the hole with a conductive paste; and (IV) pressing the laminate in the thickness direction to compress the laminate in the second layer. A step of causing a resin contained in the first layer to flow in and compressing the conductive paste to form a conductor, and after the step (II) and before the step (IV) (that is, the ( After II), the above (I
(V) at any point before), (Z) arranging at least one selected from a metal foil and a wiring pattern on at least one surface of the laminate, and the second layer is It is a layer having pores connected to both sides of the layer, and at least one selected from the porosity and the average pore diameter of the second layer is different from each other on both sides of the layer. The first layer and the second layer are the same as described above.
It is the same as the first layer and the second layer in the prepreg of the present invention. Further, the above (I) and (II) are
It may be performed in the same manner as (i) and (ii) in the method of manufacturing the prepreg described above.

By adopting such a manufacturing method, a circuit board having a low electric connection resistance and excellent connection stability can be obtained.

In the above (II), when the second layer is formed on the base material in the same manner as in the above-mentioned method for producing the prepreg, the first layer is separated after the second layer is separated from the base material. May be laminated on at least one surface of. Further, the second layer may be laminated on at least one surface of the first layer without being separated from the base material.

When the above separation is not carried out, the above (II)
In the above, the first layer and the second layer may be laminated so as to be in contact with each other, and in that case, the base material may be separated at an arbitrary point before (IV). Above (III)
When the base material is separated after the above step, the conductive paste is filled in the holes by the thickness of the base material.
At the time of V), the conductive paste can be further compressed, and a circuit board having more excellent characteristics can be obtained.

Further, in the above (III), as the holes, through holes or non-through holes may be formed. You can choose according to your needs. If the hole does not penetrate, it becomes a blind via hole.

In addition, in the above (III), when the metal foil or the wiring pattern is already arranged on one surface of the laminate, the hole is opposite to the surface on which the metal foil or the wiring pattern is arranged. It may be formed from the side surface.
At this time, even if the hole penetrates the laminated body portion, if it does not penetrate the metal foil or the wiring pattern, it becomes a blind via hole.

Further, in the above (Z), when a metal foil is arranged on at least one surface of the laminate,
(V) The method may further include a step of processing the metal foil to form a wiring pattern.

The method of forming holes and the method of forming wiring patterns will be described later.

The circuit board of the present invention comprises an insulating layer in which at least one first insulating layer (third layer) and at least one second insulating layer (fourth layer) are integrated, and wiring. A pattern layer, the wiring pattern layer is disposed on at least one surface of the integrated insulating layer, and the first insulating layer (third layer) is a layer containing a resin. The second insulating layer (fourth layer) is a layer having pores connected to both surfaces of the second insulating layer, and the first insulating layer (third layer).
In the layer having a structure in which the resin contained in (1) is introduced, at least one selected from the porosity and the average pore diameter of the layer having pores is different on both sides of the layer. Such a circuit board can be obtained by using the above-described prepreg and / or the above-described method for manufacturing a circuit board. The layer having the voids is the same as the second layer in the prepreg described above, and the first insulating layer (third layer) and the second insulating layer (fourth layer) are , A layer obtained by compressing the first layer and the second layer in the prepreg described above.

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the examples shown below.

(Embodiment 1) FIG. 1A is a schematic sectional view showing an example of a prepreg in the present invention. Figure 1
The prepreg 3 shown in (a) includes a second layer 1 and a first layer 2.
It has a two-layer structure in which and are laminated.

When the above-mentioned materials are used for the first layer 2 and the second layer 1 and the prepreg 3 is heated and pressed at a temperature above the temperature at which the resin contained in the first layer 2 melts, the first layer The resin in 2 melts and flows into the second layer 1,
The composite body 6 in which the fourth layer 4 and the third layer 5 are integrated as shown in (b) is obtained. The fourth layer 4 has a structure in which the resin contained in the first layer 2 flows into the pores of the second layer 1.

That is, even if an insulating material having a low compressibility, which could not obtain a good compression when the heating and pressurizing treatment was performed alone, was used as the first layer 2, the second layer was used. With the structure having the layer 1 of 1., the prepreg 3 having high compressibility can be obtained.

Next, another example of the prepreg of the present invention will be described with reference to FIG.

FIG. 2 (a) is a schematic sectional view showing an example of the prepreg in the present invention. As shown in FIG. 2A, the prepreg 9 has a three-layer structure in which the second layer 7 is formed on both surfaces of the first layer 8. When the prepreg 9 is heated and pressed in the same manner as in the example of FIG.
As shown in (b), the composite body 1 in which the fourth layer 10 into which the resin in the first layer 8 has flowed and the third layer 11 are integrated
It becomes 2. In this example, since the second layer 7 is formed on both surfaces of the first layer 8, both surfaces of the prepreg 9 have compressibility, and the prepreg has more effective compressibility. .

Next, another example of the prepreg of the present invention will be described with reference to FIG.

3 (a) and 3 (b) are schematic sectional views showing an example of the prepreg of the present invention. Figure 3
The prepreg 15 shown in (a) has a four-layer structure in which the second layers 13 and the first layers 14 are alternately laminated. Further, the prepreg 18 shown in FIG.
And a first layer 17 are alternately laminated to form a five-layer structure.

As shown in FIG. 3A, the prepreg 15
Then, the second layer 13 exists only on one surface of the prepreg 15. Further, as shown in FIG. 3B, the prepreg 18
Then, the second layer 16 is present on both surfaces of the prepreg 18. Also, both prepregs have a second inside the prepreg.
Have layers. In the example shown in FIG. 3, the second
Although only one layer is present inside the prepreg, a plurality of layers may be present as long as the first layer and the second layer are alternately laminated.

When such a prepreg is subjected to heat and pressure treatment, even when an insulating material having low compressibility alone is used as the first layer, as in the examples shown in FIGS. 1 and 2, It becomes possible to perform effective compression. further,
In the example shown in FIG. 3, since the second layer is also included inside the prepreg, it is possible to more effectively improve the compressibility as compared with the examples shown in FIGS. 1 and 2.

If the above method is used, not only a specific insulating material but also any material having necessary physical properties can be used.
A prepreg with good compressibility can be obtained.

(Second Embodiment) FIG. 4A is a schematic sectional view showing an example of a prepreg in the present invention. Figure 4
As shown in (a), the prepreg 22 has a second layer 19
Is a laminated body laminated on both surfaces of the first layer 20, through holes are formed as holes in the thickness direction of the laminated body, and the through holes are filled with a conductive paste 21.

Metal foils 23 are arranged on both sides of the prepreg 22 and heat and pressure treatment is performed. Then, as shown in FIG. 4B, the resin in the first layer 20 flows into the second layer 19 and the prepreg 22 is compressed. Second layer 1
9 and the first layer 20 become the fourth layer 24 and the fifth layer 25. At the same time, the conductive paste 21 is compressed to become the conductor 26, and good electrical conduction can be obtained between the metal foil 23 and the conductor 26. In this way, it is possible to obtain the circuit forming substrate 28 having good electrical continuity. Further, the circuit board can be obtained by processing the metal foil 23 of the circuit forming board 28 into a wiring pattern.

In the conventional structure in which the second layer 19 is not present, when the compressibility of the first layer 20 is low, the compression during the heat and pressure treatment becomes insufficient, so that the space between the conductor 26 and the metal foil 23 is reduced. In some cases, good electrical continuity cannot be obtained. In that case, there is a possibility that problems such as high resistance of the circuit board, increase of resistance value variation, deterioration of connection stability, and deterioration of environmental test reliability may occur.

In addition, the resin contained in the first layer 20 is melted and moved, so that the metal foil 23 as the wiring metal is formed.
There is a possibility that the adhesiveness between the first layer 20 and the first layer 20 is reduced, and a problem such as a decrease in reliability in an environmental test occurs.

On the other hand, in the above example, it is possible to obtain a circuit-forming board having good electrical continuity, and the circuit board has a low resistance, a reduced resistance value variation, a connection stability, and reliability for environmental tests. It is possible to obtain effects such as improvement.

Further, in the above example, the second layer 19
Also plays a role of a reinforcing material for the first layer 20. Therefore, when compressing the prepreg, the first layer 2
It is possible to prevent the resin contained in 0 from melting and moving in the surface direction. When the movement in the plane direction is suppressed,
The compression improves the adhesion between the metal foil 23 and the insulating layer in which the second layer 20 and the first layer 19 are integrated, and the metal foil 2
Even after 3 is processed into a wiring pattern, high reliability can be obtained with respect to the environment such as temperature and humidity.

The method of forming the holes is not particularly limited. For example, a laser processing method using a carbon dioxide gas laser or a YAG laser, a mechanical processing method using a drill, a puncher, or the like, which is commonly used as a hole processing method for a circuit board, may be used.

When the through holes are opened by the laser, the tapered through holes are usually opened, and the hole diameters on both surfaces of the prepreg are different. In this way, when the through-hole diameter is different on both sides of the prepreg, when the type of the second layer arranged on both sides of the prepreg is different, or when the type of the metal foil arranged on both sides of the prepreg is different,
A second layer having different average pore diameters and / or porosities may be laminated on each surface of the prepreg. Further, it is only necessary to stack second layers having different average pore diameters and / or open areas on both sides of the self layer. The compression state of both surfaces of the prepreg can be arbitrarily controlled, and a circuit-forming substrate in which the prepreg is controlled to a desired state can be obtained.

As the conductive paste with which the holes are filled, for example, a resin composition containing a conductive filler may be used. The conductive paste becomes a conductor by being compressed during the heat and pressure treatment of the prepreg, and the conductivity is improved.

The conductive filler is not particularly limited as long as it has conductivity. Among them, at least one metal selected from gold, silver, copper, nickel, palladium, lead, tin, indium and bismuth, an alloy thereof,
Alternatively, it is preferable to use a filler made of a mixture or the like. You may use the coat filler which coated the said metal / alloy on the particle | grains which consist of oxides, such as alumina and silica, or organic synthetic resin. The shape of the filler is not particularly limited. For example, powder, fibrous filler, powder granules, spherical particles, or a mixture thereof may be used.

The resin used as the binder of the conductive paste is not particularly limited. For example, liquid epoxy resin,
A polyimide resin, a cyanate ester resin, a phenol resol resin, or the like may be used.

The epoxy resin is not particularly limited. For example, epoxy groups such as glycidyl ether type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, alicyclic epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, etc. An epoxy resin containing two or more may be used. Furthermore, if necessary, additives such as a solvent and a dispersant such as butyl cellosolve, ethyl cellosolve, butyl carbitol, ethyl carbitol, butyl carbitol acetate, ethyl carbitol acetate, and α-terpineol are added to the resin. It may be contained.

The conductor is not limited to the one using the above conductive paste. For example, gold,
Silver, copper, nickel, palladium, lead, tin, indium,
It is possible to use an interstitial via connecting material of a type that obtains conduction by pressure contact, such as a via post made of a metal such as bismuth.

The method of filling the holes with the conductive paste is not particularly limited. For example, a printing method or the like may be used. As a printing method, for example, a prepreg in which holes are formed is placed on a vacuum suction table through a sheet of paper, and the conductive paste is printed and filled. According to this method, the resin component contained in the conductive paste is sucked into the paper by the effect of vacuum adsorption and the capillary phenomenon of the paper and the packing density of the conductive particles in the holes can be increased. Also,
At the same time, since voids are generated between the conductive particles, the packing density of the conductive particles can be further increased when the prepreg is compressed during the process of manufacturing the circuit board.

The metal foil is not particularly limited. For example, a copper foil such as an electrolytic copper foil or a rolled copper foil usually used for a circuit board may be used. The thickness of the metal foil is not particularly limited. From the viewpoint of workability and productivity, the range of about 9 μm to 35 μm is preferable.

Next, the heating and pressurizing treatment of the prepreg will be described. The conditions of heat and pressure treatment differ depending on the material used as the prepreg. For example, as described above,
In the case of the prepreg using the first layer in which the aramid nonwoven fabric is impregnated with the epoxy resin, the pressure is 5 MPa (50 kgf / c
m ² ), a temperature of 200 ° C., and heating and pressing for 1 hour are preferable.
In the case of a prepreg using the first layer in which a polyimide adhesive (thickness: about 6 μm) is formed on a polyimide film (thickness: 13 μm), the pressure is 15 MPa (150 kgf /
cm ² ), a temperature of 200 ° C. and heating and pressurization for 1 hour are preferable.

As shown in FIGS. 4A and 4B, since the resin from the first layer 20 flows into the second layer 19 of the prepreg 22, the prepreg 22 is compressed. It is necessary to control the compression rate of the prepreg 22 during the heating and pressing process.

The compression rate of the prepreg is, for example, 2% to
It is in the range of 30%. Even if the compressibility is less than 2%, the electrical continuity of the through hole can be ensured due to the presence of the raised portion of the conductive paste. When the compressibility is 2% or more, a sufficient compressive force is applied to the contact portion between the conductive fillers in the conductive paste and the contact portion between the conductive paste and the metal foil, so that they are firmly adhered to each other. it can. Therefore, the connection resistance as an interstitial via becomes low, and the stability of connection can be improved. Further, depending on the materials used for the prepreg and the conductive paste, when the compressibility of the prepreg exceeds about 30%, the obtained circuit board is deformed,
Internal stress may remain.

FIG. 5 (a) is a schematic sectional view showing an example of the prepreg in the present invention. As shown in FIG. 5A, the prepreg 32 is a prepreg having a four-layer structure in which the second layers 29 and the first layers 30 are alternately laminated,
The conductive paste 31 is filled in the blind via.

Similar to the example shown in FIG. 4, the first layer 30 and the second layer 29 are laminated, a blind via is formed by a method such as laser processing, and a conductive material is formed in the blind via. The paste 31 can be filled to obtain the prepreg 32. After overlaying the metal foil 33 on the surface of the prepreg 32 where the conductive paste 31 is exposed, a heating and pressing process is performed. Then, as shown in FIG. 5B, the second layer 29
The resin contained in the first layer 30 flows into the inside of the fourth layer 3
4 and the fifth layer 35. At the same time, prepreg 3
It is possible to obtain a circuit-forming substrate 38 in which 2 is compressed and the metal foil 33 is formed on one surface. This circuit forming substrate 3
By processing the metal foil 33 of No. 8 into a wiring pattern, a circuit board can be obtained.

Also in this example, the same effect as that of the example shown in FIG. 4 can be obtained on the surface on which the metal foil 33 is laminated. Further, in this example, the surface on which the metal foil 33 is not arranged may be bonded to, for example, a separately prepared prepreg, a circuit-forming board, a circuit board, or the like.

Further, in the structure in which a large number of voids are present inside the prepreg like the conventional prepreg, dimensional change of the prepreg easily occurs due to environmental temperature, humidity or external force. On the other hand, in the case of the prepreg of the present invention, since the first layer, which is the structure of the prepreg, is covered with the resin of the matrix, the dimensional change of the prepreg can be reduced.

(Embodiment 3) FIGS. 6A to 6F.
FIG. 3 is a schematic cross-sectional view showing an example of a method for manufacturing a circuit board according to the present invention. Each drawing shows each step in the example of the manufacturing method.

First, the first layer 39 and the release film 41 having the second layer 40 formed on the surface thereof are prepared (FIG. 6A).

Next, the second layer 4 is formed on both surfaces of the first layer 39.
The releasable film 41 having 0 is laminated so that the second layer 40 and the first layer 39 are in contact with each other to produce a prepreg 42 to which the releasable film 41 is attached (Fig. 6 (b )).

Then, a through hole is formed in the prepreg by a laser processing method to produce a prepreg 43 having the through hole (FIG. 6 (c)). At this time, the through holes are formed together with the second layer 40 and the release film 41.

The printing paste is used to fill the through holes with the conductive paste 44 (FIG. 6D).

Thereafter, only the release film 41 is peeled off, and the second layer 40 is left on the surface of the first layer 39 to form the prepreg 45 (FIG. 6 (e)).

The metal foils 46 are overlapped on both sides of the prepreg 45 (FIG. 6 (e)), and heat and pressure treatment is performed to compress the prepreg 45. At this time, the prepreg 45 is effectively compressed by the presence of the second layer 40, so that the conductive paste 44 is densified and becomes a low-resistance conductor, which is good and stable between the prepreg 45 and the metal foil 46. Electrical connection is obtained.

Finally, the wiring pattern 48 is formed by processing the metal foil to obtain the circuit board 47 (FIG. 6 (f)).

For forming the wiring pattern, a usual method used for manufacturing a circuit board, for example, a photolithography method may be used.

The release film is not particularly limited as long as it has heat resistance of 100 ° C. or higher and has good processability in forming holes. For example, a polyester film, a polyimide film, a polyamide film, or the like may be used. As the polyester film, for example,
A polyethylene terephthalate (PET) film or a polyethylene naphthalate (PEN) film may be used. The releasable film serves as a mask when forming the through holes, and at the same time, has an effect that the conductive paste is additionally filled by the thickness thereof. That is, FIG.
As shown in (e), when the release film is removed, the conductive paste 44 has a structure protruding from the prepreg 45, and during the heat and pressure treatment of the prepreg, this protruding portion is also compressed by the conductive paste. The effect of contributing to the improvement of the rate can be obtained.

Further, when the above-mentioned lamination is carried out, if the heating is carried out in advance, a part of the resin contained in the first layer is melted and a small amount can be made to flow into the second layer. In this case, the first layer and the second layer are in close contact with each other, and the resin contained in the first layer can be more favorably flowed in when the prepreg is heated and pressed.

In the above manufacturing method, the second layer is formed on the surface of the first layer.
The layers can be simply arranged. When the second layer is formed by coating on the base material, the base material may be directly placed on the first layer as the release film.

Further, according to the above manufacturing method, it is possible to obtain a circuit board having good electrical connection and durability regardless of the materials and physical properties of the first layer and the second layer. Furthermore, when the effect of using a prepreg in which a conductive paste is projected by a release film is used together, a synergistic effect can be obtained to obtain a circuit board with even lower interstitial via connection resistance and high connection stability. You can

Further, as described above, instead of laminating a metal foil on the surface of the prepreg and subjecting it to heat and pressure treatment, and thereafter forming a wiring pattern, the wiring pattern is arranged on the surface of the prepreg from the beginning and heated and pressed. Processing may be performed to form a circuit board.

(Embodiment 4) FIGS. 7A to 7F.
FIG. 3 is a schematic cross-sectional view showing an example of a method for manufacturing a circuit board according to the present invention. Each drawing shows each step in the example of the manufacturing method.

First, the transfer film 50 having the wiring pattern 51 is formed on one surface of the first layer 49 by the wiring pattern 5
1 and the first layer 49 are in contact with each other, and the first layer 4
Releasable film 5 having second layer 52 on the other surface of 9
3 is arranged so that the second layer 52 and the first layer 49 are in contact with each other (FIG. 7A), and the prepreg 54 is obtained (FIG. 7).
(B)).

Next, a blind via hole is opened by laser processing until the wiring pattern 51 is exposed,
A prepreg 55 having a blind via hole is obtained (FIG. 7 (c)).

Then, the conductive paste 56 is filled in the blind via holes by using a printing method (FIG. 7).
(D)).

Only the release film is peeled off, and the second layer 5
2 is left on the surface of the first layer 49 to form the prepreg 57 (FIG. 7E).

On the surface where the conductive paste 56 is exposed,
The metal foil 58 is overlaid and subjected to heat and pressure treatment to compress the prepreg 57. At this time, the prepreg 57 is effectively compressed by the presence of the second layer 52, so that the conductive paste 56 is densified and becomes a low resistance conductor, and a good and stable electrical conductivity is obtained between the prepreg 57 and the metal foil 58. Connection is obtained.

Finally, the wiring pattern 59 is formed by processing the metal foil, and the circuit board 60 can be obtained (FIG. 7 (f)).

In the above manufacturing method, the second layer is formed on the surface of the first layer.
The layers can be simply arranged. When the second layer is formed by coating on the base material, the base material may be directly placed on the first layer as the release film.

Further, according to the above manufacturing method, it is possible to obtain a circuit board having good electrical connection and durability regardless of the materials and physical properties of the first layer and the second layer.

Further, this manufacturing method is a manufacturing method which can effectively utilize a wiring pattern formed in advance,
A circuit board having various wiring patterns can be easily manufactured.

Further, as shown in FIG. 7F, the wiring pattern 51 is buried inside the circuit board when the circuit board is formed, so that the conductive paste can be compressed more.

As the transfer film having a wiring pattern, for example, a commercially available aluminum carrier on which a copper foil is laminated via a release layer may be used. in this case,
A wiring pattern may be formed in advance on the copper foil by an etching method or the like. An aqueous solution of iron chloride, an aqueous solution of ammonium persulfate, or the like may be used for the etching. After the heat and pressure treatment, the aluminum carrier which is the transfer film can be removed by etching with hydrochloric acid or the like. In this case, it is possible to obtain a circuit board having the same shape as that of FIG. 6 (f) in the third embodiment.

In the above manufacturing method, the compression effect of the second layer, the projection effect of the conductive paste, and the pressing effect of the wiring pattern are combined to increase the compression ratio of the prepreg and the conductive paste. Can be effective.

Also, instead of the method of laminating the metal foil on the prepreg and performing the heat and pressure treatment, and then forming the wiring pattern, the wiring pattern is laminated on the prepreg from the beginning and the heat and pressure treatment is performed to form the circuit. A substrate may be formed.

(Embodiment 5) Another example of the method for manufacturing a circuit board according to the present invention will be described with reference to FIG.

Prepregs 62 and 63 are superposed on both sides of a circuit board 61 formed by the same method as in the third embodiment.
Further, metal foils 64 and 65 are overlaid thereon (FIG. 8).
(A)).

After these are heated and pressed at once, the metal foils on both sides are processed to form a wiring pattern, whereby a multilayer circuit board 66 can be manufactured (FIG. 8).
(B)).

Further, instead of the method of laminating metal foils and subjecting them to heat and pressure treatment and then forming a wiring pattern,
You may form a multilayer circuit board by laminating | stacking a wiring pattern from the beginning and performing a heating and pressurizing process.

By repeating such a method, a multilayer circuit board having low resistance, stable electrical connection, and durability can be obtained, and physical properties such as the type and compressibility of the first and second layers can be obtained. However, it becomes possible to manufacture it easily.

Not only the above-mentioned materials, but also materials and structures satisfying the contents of the invention may be used.

Further, the processing method in each step described in each embodiment is not limited to the above-mentioned method, and another method may be used as long as it complies with the content of the invention. .

[0123]

EXAMPLES The present invention will be described in more detail with reference to examples. In this example, a circuit board was manufactured according to the method shown in the third embodiment (FIG. 6). The present invention is
The present invention is not limited to the examples shown below.

The sample of this example was prepared as follows.

First, a porous m-aramid layer was prepared as the second layer as follows.

A solution was prepared by dissolving m-aramid (Conex manufactured by Teijin Ltd.) in NMP, and the solution was applied onto a PET film (thickness 18 μm) as a base material. The coating width was 35 cm. Subsequently, the applied solution was dipped in methyl alcohol at room temperature together with the base material to form a gelled m-aramid layer on the base material. Further, the gelled m-aramid layer is washed with water and dried (normally, in an air atmosphere, 8
0 ° C.) and a thickness of 10 μm on the PET film
-Formed an aramid porous layer. At this time, the porosity of the surface of the m-aramid layer on the PET substrate side was 11%,
The average pore size was 0.3 μm. The open area ratio of the surface opposite to the PET substrate was 9%, and the average pore diameter was 0.05 μm.

A commercially available FR4-equivalent glass epoxy prepreg layer (GEA-67 manufactured by Hitachi Chemical Co., Ltd.) was used as the first layer.
N, thickness 100 μm) was prepared, and a PET film having an m-aramid porous layer was laminated on both surfaces of the glass epoxy layer so that the m-aramid porous layer and the glass epoxy layer were in contact with each other. . Thus, a prepreg in which the m-aramid porous layer was attached to both surfaces of the glass epoxy layer was obtained.

Next, through holes (hole diameter: 200 μm) were formed in the above prepreg in a predetermined pattern by the laser processing method. At this time, the through hole is formed with a glass epoxy layer, P
The ET film and the m-aramid porous layer were formed together.

Next, the through holes were filled with a conductive paste by using a printing method. The conductive paste is C
A mixture of u powder and epoxy resin was used.

Subsequently, only the PET film was peeled off from the prepreg to obtain a prepreg in which only the m-aramid porous layer remained on the surface of the epoxy layer. The conductive paste was projected from the through holes of the prepreg by the thickness of the peeled PET film.

Copper foil (thickness 18 μm was formed on both surfaces of this prepreg.
m) was laminated, and after the copper foils were laminated, the prepreg was heated and pressed to be compressed. The heating and pressurizing treatment was carried out using a vacuum hot press machine at a temperature of 200 ° C. and a pressure of 5 MPa (50 kgf
/ Cm ² ), for 60 minutes. By the above compression, the epoxy resin in the glass epoxy layer is melted, and m-
It was confirmed by cutting a part of the sample and measuring the cut surface with an electron microscope that the liquid was flowing into the aramid porous layer.

Finally, a wiring pattern is formed by processing the above copper foil by using a photolithography method and an etching method, and a wiring structure in which the front and back wirings are alternately connected in series by 1600 IVHs is formed. A circuit board having the above was obtained. In addition, 60 sample circuit boards were prepared using the above method.

As a conventional example, 60 samples of circuit boards using only the epoxy layer as the first layer were prepared. The manufacturing method is exactly the same as that described above, including the materials, except that the m-aramid porous layer that is the second layer is not used (that is, the PET film is not used).

The connection resistance of the interstitial vias was measured for the circuit boards of Examples and Comparative Examples prepared as described above. The serial 4-terminal method was used for the measurement. A graph showing the result is shown in FIG. FIG. 9 shows the value of the connection resistance value of the path in which 1600 IVHs are connected in series by the above wiring structure, and the frequency of occurrence thereof.

As shown in FIG. 9, it can be seen that the example has a lower connection resistance value and less variation than the comparative example.

[0136]

As described above, according to the present invention, excellent dimensional stability, low interstitial via connection resistance, excellent connection stability, etc. are obtained irrespective of the material, physical properties, combination, etc. of the insulating layer. It is possible to provide a prepreg and a circuit board that realize the above. Moreover, the manufacturing method of them can be provided.

[Brief description of drawings]

1A is a schematic sectional view showing an example of a prepreg according to the present invention, and FIG. 1B is a schematic sectional view of a composite obtained by compressing the prepreg of FIG.

FIG. 2 (a) is a schematic sectional view showing an example of the prepreg of the present invention, and FIG. 2 (b) is a schematic sectional view of a composite obtained by compressing the prepreg of (a).

3A and 3B are schematic sectional views showing an example of a prepreg in the present invention.

4A and 4B are schematic cross-sectional views showing an example of a prepreg and a circuit-forming board according to the present invention, and an example of a method for manufacturing a circuit board according to the present invention.

5A and 5B are schematic cross-sectional views showing an example of a prepreg and a circuit-forming board according to the present invention, and an example of a method for manufacturing a circuit board according to the present invention.

6A to 6F are schematic cross-sectional views of a board in each step showing an example of a method for manufacturing a circuit board according to the present invention.

7 (a) to 7 (f) are schematic cross-sectional views of a board in each step showing an example of the method for manufacturing a circuit board according to the present invention.

8A and 8B are schematic cross-sectional views of a board in each step showing an example of the method for manufacturing a circuit board according to the present invention.

FIG. 9 is a diagram showing an appearance frequency distribution of IVH connection resistance in a double-sided circuit board measured in an example of the present invention.

[Explanation of symbols]

1, 7, 13, 16, 19, 29, 40, 52 Second layer 2, 8, 14, 17, 20, 30, 39, 49 First layer 3, 9, 15, 18, 22, 32, 42, 43, 45,
54, 55, 57, 62, 63 Prepreg 4, 10, 24, 34 Fourth layer 5, 11, 25, 35 Third layer 6, 12 Composite 21, 31, 44, 56 Conductive paste 23, 33 , 46, 58, 64, 65 Metal foils 26, 36 Conductors 28, 38 Circuit forming substrates 41, 53 Release film 47, 60, 61, 66 Circuit boards 48, 51, 59 Wiring pattern 50 Transfer film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 1/03 630 H05K 3/40 K 3/40 C08L 101: 00 // C08L 101: 00 H01L 23/12 N (72) Inventor Fumio Echigo 1006, Kadoma, Kadoma City, Osaka Prefecture F-term (Reference) in Matsushita Electric Industrial Co., Ltd. AK19B AK19D AK19E AK42 AK47B AK47D AK47E AK49B AK49D AK49E AK53 AT00A AT00B AT00D AT00E BA02 BA03 BA04 BA05 BA08 BA10A BA10B BA10C BA10D BA10E BA25 CA23A CA23C CA23E DC11B DC11D DC11E DE01 DH01A DH01B DH01C DH01D DH01E DJ01B DJ01D DJ01E EH46 EH462 EJ17 EJ172 EJ42 EJ422 EJ82 EJ821 EJ86 EJ862 GB43 JG04A JG04C JG04E YY00B YY00D YY00E 5E317 BB01 BB03 BB11 BB12 BB13 BB14 BB15 C C17 CC25 GG01 GG09

Claims (31)

[Claims] 1. A laminate including at least one first layer and at least one second layer, wherein the first layer is an insulating layer containing a resin, and the second layer is A prepreg, which is a layer having pores connected to both surfaces of its own layer, wherein at least one selected from the porosity and the average pore diameter of the second layer is different on both surfaces of its own layer. 2. The prepreg according to claim 1, wherein the second layer is a porous layer. 3. The porosity of the second layer is 20% by volume to.
The prepreg according to claim 1, which is in a range of 80% by volume. 4. The prepreg according to claim 1, wherein the first layer and the second layer are alternately laminated, and both outermost layers are composed of the second layer. 5. The prepreg according to claim 4, wherein the outermost layers have different average pore sizes. 6. The prepreg according to claim 4, wherein the porosities of the outermost layers are different from each other. 7. The resin contained in the first layer is contained in the void portion of the second layer in contact with the first layer. Prepreg. 8. The prepreg according to claim 1, wherein the first layer has a structure in which an insulating core material is impregnated with a resin. 9. The prepreg according to claim 1, wherein the first layer contains a filler. 10. The prepreg according to claim 9, wherein the average pore size of the second layer in contact with the first layer is smaller than the average particle size of the filler. 11. The prepreg according to claim 1, wherein the second layer is made of aramid. 12. The prepreg according to claim 1, wherein the second layer is made of polyimide. 13. The prepreg according to claim 1, wherein the second layer is made of polytetrafluoroethylene. 14. An insulating layer in which at least one first insulating layer and at least one second insulating layer are integrated,
A wiring pattern layer, the wiring pattern layer is disposed on at least one surface of the integrated insulating layer, the first insulating layer is a layer containing a resin, the second insulating layer The insulating layer is a layer having a structure in which the resin contained in the first insulating layer has flowed into a layer having voids connected to both surfaces of its own layer, and the porosity of the layer having voids And a circuit board in which at least one selected from the average pore size is different from each other on both sides of the self layer. 15. (i) forming a first layer which is an insulating layer containing a resin, and (ii) forming a second layer laminated on at least one surface of the first layer. And a step of forming a laminated body of the first layer and the second layer, the second layer is a layer having void portions connected to both surfaces of its own layer, and the second layer A method for producing a prepreg in which at least one selected from the porosity and the average pore size of the layer is different from each other on both sides of the layer. 16. The step (ii) includes: (ii-a) a step of applying a solution of a resin contained in the second layer onto a base material; and (ii-b) included in the second layer. And (ii-c) forming the second layer on the base material by washing and drying the gelled resin, and (ii-d) the second step. 16. The method for producing a prepreg according to claim 15, further comprising the step of laminating the second layer on at least one surface of one layer. 17. The method according to claim 1, wherein the step (ii-b) is performed by replacing the solvent in the solution with another solvent.
6. The method for producing a prepreg according to item 6. 18. The method for producing a prepreg according to claim 16, wherein the resin contained in the second layer is aramid. 19. The method for producing a prepreg according to claim 16, wherein the base material is a resin film. 20. The (ii) is (ii-A) on at least one surface of the first layer,
Applying a solution of a resin contained in the second layer, (ii-B) gelling the resin contained in the second layer, and (ii-C) washing the gelled resin And a step of forming the second layer on at least one surface of the first layer by drying the prepreg. 21. The method of (ii-B) is performed by replacing the solvent in the solution with another solvent.
0. The method for producing a prepreg according to item 0. 22. The method for producing a prepreg according to claim 20, wherein the resin contained in the second layer is aramid. 23. (I) forming a first layer which is an insulating layer containing a resin, and (II) forming a second layer laminated on at least one surface of the first layer. A step of forming a laminated body of the first layer and the second layer, and (III) a step of forming a hole in a thickness direction of the laminated body and filling the hole with a conductive paste. (IV) The laminated body is pressed to be compressed in the thickness direction, the resin contained in the first layer is caused to flow into the second layer, and the conductive paste is compressed to form a conductor. Forming step, and (Z) arranging at least one selected from a metal foil and a wiring pattern on at least one surface of the laminate after (II) and before (IV). And the second layer is a layer having pores connected to both surfaces of its own layer, Serial least one is selected from open area ratio and average pore diameter of the second layer differ from each other both in its own layer, the manufacturing method of the circuit board. 24. In the step (Z), a metal foil is disposed on at least one surface of the laminate, and the method further comprises: (V) processing the metal foil to form a wiring pattern. A method for manufacturing the circuit board described. 25. The method (II) includes: (II-a) a step of applying a solution of a resin contained in the second layer onto a base material; and (II-b) included in the second layer. Forming a second layer on the base material by washing and drying the gelled resin (II-c), and (II-d) the first 25. The step of laminating the second layer on at least one surface of the layer according to claim 23.
A method for manufacturing a circuit board according to. 26. The method according to claim 2, wherein the step (II-b) is performed by replacing the solvent in the solution with another solvent.
5. The method for manufacturing a circuit board according to item 5. 27. The method of manufacturing a circuit board according to claim 25, wherein the resin contained in the second layer is aramid. 28. The method for manufacturing a circuit board according to claim 25, wherein the base material is a resin film. 29. (II-A), (II-A) applying a solution of a resin contained in the second layer onto the first layer, and (II-B) the second layer. A step of gelling a resin contained in the layer, and (II-C) washing and drying the gelled resin to form the second layer on at least one surface of the first layer. 25. The process according to claim 23 or 24, including
A method for manufacturing a circuit board according to. 30. The step (II-B) is carried out by replacing the solvent in the solution with another solvent.
9. The method for manufacturing a circuit board according to item 9. 31. The method of manufacturing a circuit board according to claim 29, wherein the resin contained in the second layer is aramid.