KR100713976B1 - Method for manufacturing printed wiring board and printed wiring board produced by the method - Google Patents

Abstract

The present invention relates to a method for manufacturing a printed wiring board having a circuit embedded in an insulating resin layer, wherein: A) 0.5 µm to 1 µm thicker than the surface roughness (Rz) of the adhesive surface of the copper foil on one surface of the copper foil. Using a copper foil with an insulating layer provided with a cured resin layer having a cured resin layer and having a semi-cured resin layer containing a skeleton on the cured resin layer, the copper foil surface is etched to form a circuit to form a circuit sheet with an insulating layer. Forming, B) hot press molding by overlapping the semi-cured resin layer of the circuit sheet with the insulating layer to be pasted, and the copper foil of the circuit portion impregnated the cured resin layer, and is embedded in the insulating resin layer It is a manufacturing method of the printed wiring board characterized by including each process of forming the printed wiring board provided with a circuit. According to the present invention, excellent laser processing performance and a dielectric layer thickness of a capacitor circuit can be maintained well, and a printed wiring board can be provided with the outer layer circuit embedded in the insulating resin substrate.

Description

Method for manufacturing printed wiring board and printed wiring board produced by the method}

1: is a schematic diagram which shows the manufacturing flow of the copper foil with an insulating layer.

It is a schematic diagram which shows the manufacturing flow of the copper foil with an insulating layer.

It is a schematic diagram which shows the manufacturing flow of the copper foil with an insulating layer.

It is a schematic diagram which shows the manufacturing flow of the copper foil with an insulating layer.

It is a schematic diagram which shows the manufacturing flow of copper foil with an insulating layer.

It is a schematic diagram which shows the manufacturing flow of the circuit sheet with an insulating layer from the copper foil with an insulating layer.

It is a schematic diagram which shows the manufacturing flow of the circuit sheet with an insulating layer from the copper foil with an insulating layer.

8 is a schematic diagram showing a press image using a circuit sheet with an insulating layer and an inner core material.

It is a schematic diagram which shows the laminated image of the copper foil with a dielectric layer.

It is a schematic diagram which shows the formation flow of a capacitor circuit.

It is a schematic diagram which shows the formation flow of a capacitor circuit.

<Brief Description of Drawing Reference Symbols>

1a. Printed wiring board 1b. Printed wiring board with capacitor circuit

2. Copper foil with insulation layer 3. Copper foil layer (copper foil) 4. Curing resin layer

5..Framework (non-woven or woven fabric) 6 .. Semi-hardening resin layer

7..Circuit sheet with insulation layer 10 .. (Multilayer) printed wiring board

11. dielectric layer 12. copper clad laminate 20. heating furnace

21. Heater 22. Compression roller

S ₁ , S ₂ .. coating

C ₁ , C ₂ , C ₃ .. Circuit

R. Etching Resist Layer

This invention relates to the manufacturing method of the copper foil with an insulation layer, the copper foil with an insulation layer obtained by the manufacturing method, and the multilayer printed wiring board using the copper foil with an insulation layer.

In recent printed wiring boards, the following two things are always required. One is required to be thinner and lighter in accordance with light and small size of electronic devices and electrical appliances on which printed wiring boards are mounted, and further improvement in wiring density and component mounting density, that is, fine pitch is required. have. At the same time, it is common to form a capacitor circuit in the inner circuit portion of a multilayer printed wiring board to reduce power consumption and stabilize supply voltage of electronic devices and the like.

Technical Background on Laser Perforation: First, the technical background on fine pitching will be described. In order to improve the wiring density, as disclosed in Japanese Patent Laid-Open No. 11-195853, it has become common to form a small diameter via-hole using a laser processing method. By the way, with the spread of laser drilling, it has been found that in the multilayer printed wiring board manufactured using FR-4 prepreg which is a conventional glass epoxy substrate, laser drilling workability regarding the inner wall shape of a via hole is inferior. . The first problem was the presence of glass cloth, which is a skeleton of glass epoxy substrate. Glass cloth has knitting, and since the glass itself is inferior in laser workability, perforation with good precision was impossible.

Therefore, the present inventors supply to the market a copper foil with a resin provided with only a semi-cured resin layer containing no skeleton material on the surface of the copper foil, as disclosed in International Publication No. WO97 / 02728. Using the construction method, it became possible to manufacture the copper clad laminate excellent in the laser drilling processability, and to supply the high quality multilayer printed wiring board. That is, since the copper foil with resin does not contain a skeleton material in the resin layer, it is lightweight and has the characteristics of excellent laser drilling processability in the sense that the via hole inner wall part can be smoothed and the blow hole can be eliminated. The disadvantages of not containing ash include:

That is, the copper foil laminated board manufactured using only copper foil with resin had a problem that the mechanical strength which a resin layer has with respect to external forces, such as bending, tension, and an impact, was not enough. And since the copper foil with resin does not have a reinforcing material, in the copper foil laminated board manufactured using only the copper foil with resin, the thickness of the insulating layer in the same plane will fluctuate extremely in the system where the copper circuit density of an inner layer circuit is nonuniform, and control becomes difficult. . The coefficient of thermal expansion as a material is large, and stress is easily generated at an interface with a dissimilar material, for example, a copper circuit, adversely affecting reliability. In addition, since the copper foil laminated plate manufactured using only the copper foil with resin is low in strength, various drawbacks, such as a pad invading at the time of wire bonding of an IC chip and incapable of obtaining a stable joint, are pointed out.

In the field of prepregs, on the other hand, as disclosed in Japanese Laid-Open Patent Publication No. 2003-213019, a product which has studied the skeleton material has been supplied as a method of improving the laser drilling processability while leaving the above-described mechanical strength intact. . That is, when glass crosslinking is used for a skeleton material, it has been considered that laser drilling workability is inferior in general. Therefore, it has become common to use what is called a nonwoven fabric type as a skeletal material, without using the cross-type thing with knitting. By using a nonwoven fabric, the nonuniformity of the cross yarn seen with the cross-type frame | skeleton material improved, and the laser perforation property improved significantly.

Technical background of a printed circuit board comprising the capacitor circuit: Next, a description about the technical background to the capacitor circuit board. When manufacturing a capacitor circuit board using a copper clad laminated board, it uses the double-sided copper foil laminated board which consists of what is called a copper foil layer of each double-sided surface, and the dielectric layer located between both copper foil layers, and has the shape of desired shape of the copper foil layer of both sides. It is common to carry out etching process with a capacitor electrode, and to form the capacitor structure of the state which sandwiched the dielectric layer in the capacitor electrodes of both surfaces in the target position.

The capacitor formed is required as basic quality to have the largest possible capacitance. Capacitance (C) is calculated from the formula _{C = εε 0 (A / d} ) (ε 0 is the permittivity of the vacuum). Therefore, to increase the capacitor capacity, i) the surface area A of the capacitor electrode is increased. ii) The thickness d of the dielectric layer is made thin. iii) The dielectric constant epsilon of the dielectric layer is increased. What is necessary is just to employ | adopt one of these methods.

By the way, regarding the surface area A of i), the same request | requirement is made also to a printed wiring board in accordance with the recent trend of light and short reduction of electronic and electrical equipment, but it takes a wide area of a capacitor electrode in the area of a fixed printed wiring board. Almost impossible. As for the thickness d of the dielectric layer of ii), if the dielectric layer contains a skeleton such as a conventional glass cloth as represented by a prefrag, the skeleton causes a limitation in thinning. On the other hand, if a skeleton material is simply omitted using a conventional dielectric layer constituent material, there arises a problem that the dielectric layer at the portion where the copper foil layer is etched away is destroyed by the shower pressure of the etching solution when the capacitor electrode is formed by etching. In view of this, it has been generalized to consider increasing the relative dielectric constant? Of the dielectric layer of iii).

That is, as disclosed in Japanese Patent Laid-Open No. 2003-198091, the structure of the dielectric layer is made of a skeleton material such as glass cross, which is required to be thinned by nonwoven fabric of the skeleton material, and the thickness of the entire dielectric layer is made thin. In addition, the capacitor capacitance has been increased by using a resin in which a dielectric filler is dispersed and contained in the constituent material of the dielectric layer.

Technical Background of Conventional Printed Wiring Board Shape: In addition, in a conventional printed wiring board, a circuit formed by etching a copper foil layer protrudes from the outer layer surface, and the circuit is physically scratched, so that a defect such as a circuit break or a circuit peeling occurs. This is happening. Therefore, the more the printed wiring board in which the fine circuit was formed, the more careful handling is required, and it causes overpacking and the fall of work efficiency. On the other hand, if the circuit of the outer layer is made to be embedded in an insulating base, the problem can be solved. As disclosed in Japanese Patent Application Laid-Open No. 2896116, Japanese Patent Application Laid-Open No. 2000-332387, and Japanese Patent Application Laid-open No. 09-191178, Techniques are disclosed.

However, in the prepreg containing the conventional skeleton material, a method of impregnating and drying the resin component in the skeleton material is conventionally employed, which causes problems related to laser drilling workability, and fully satisfies the requirements for fine pitching. It is difficult to do. On the other hand, the capacity of the built-in capacitor circuit is required to further increase the capacity, and further, the demand for stabilization of the capacitance gradually increases, and there is a phenomenon in which the demand for stabilization of the dielectric layer thickness cannot be satisfied.

Problem regarding laser drilling workability : In order to improve laser drilling workability and meet the demand of fine pitch formation, it is thought that what is necessary is just to make thickness of a skeleton material thin. By the way, the nonwoven fabric itself is inferior in strength compared with the cross type, and there existed a fault that the nonwoven fabric itself was easy to produce | generate a defect by the resin weight impregnated when carrying out resin impregnation and lifting the nonwoven fabric from immersed resin. And even if it is a cross type woven fabric, the thinner the thickness, the same problem as the nonwoven fabric had arisen.

Therefore, while achieving the purpose of making the thickness of the insulating resin layer thin for weight reduction, the amount of resin impregnated into a nonwoven fabric or a woven fabric is reduced, and a prepreg using a thinner nonwoven fabric or a woven fabric has been tried to be supplied. By the way, a copper clad laminated board is produced by sticking copper foil to a prepreg by press working. At this time, the surface of the copper foil is subjected to rough processing with irregularities, and the roughening treatment penetrates into the resin of the substrate to obtain an anchor effect to improve the adhesion strength. The amount of resin to be impregnated is reduced to a predetermined level or less. If the surface of the prepreg and the rough surface of the copper foil are brought into contact with each other, the resin adhesion surface of the substrate deteriorates, the peeling strength is degraded, and the direct contact with the skeleton causes the possibility of promoting migration along the fibers of the skeleton. .

From this point of view, the skeleton contained in the insulating resin layer when the copper clad laminate is manufactured is made as thin as possible to increase the resin content in the insulating resin layer and to prevent the roughening of the adhered copper foil and the contact of the skeleton more safely. Materials and methods have been required.

Tasks relating to a printed circuit board comprising the capacitor circuit: in the dielectric layer of the other hand, the capacitor circuit, the occurrence of the case where moisture migration phenomenon becomes a problem. The migration phenomenon in the dielectric layer containing the skeleton material causes the copper component of the copper plating layer of the printed wiring board or the constituent metal component of the dielectric filler to electrophoretically diffuse and move along the interface between the skeleton material and the resin, causing short defects between adjacent circuits. Will. It is thought that this phenomenon easily occurs due to the presence of the skeleton (particularly the cross type). In addition, it is because resin which disperse | distributed dielectric filler with considerable high filling rate is used for the layer used as a dielectric layer.

Therefore, there has been a demand for a method of manufacturing a printed wiring board which can be formed without any skeleton material in the dielectric layer of the capacitor circuit, and which is not destroyed by the shower pressure of the etching liquid during etching.

Problems Regarding the Shape of a Printed Wiring Board: In order to make the outer layer circuit of a normal printed wiring board embedded in an insulating substrate, a complicated process is generally employed, such as filling the circuit with resin and polishing it again to create a buried state. In other words, technology could not be widely used in the market.

From the problems described above, there has been a demand for a method for producing a printed wiring board that can maintain a good laser processing performance capable of further improving fine pitch and at the same time maintain a good thickness of the dielectric layer for forming a capacitor circuit. In addition, if the outer circuit of this printed wiring board is embedded in the insulating resin base material, not only does it have a very high handling property as a printed wiring board but also it can effectively prevent physical circuit damage.

Hereinafter, although the manufacturing method of the printed wiring board which concerns on this invention is demonstrated, these manufacturing methods are demonstrated in the simplest form, and those skilled in the art can apply the method demonstrated below, and can manufacture a highly multilayered printed wiring board. do. In addition, the following manufacturing method is a basic concept used for manufacture of a normal printed wiring board (hereinafter referred to as "manufacturing method 1"), and a printed wiring board provided with a capacitor circuit (hereinafter referred to as "manufacturing method 2"). It will be described by dividing by. This is because in the case of a printed wiring board having a capacitor circuit, a case in which a dielectric filler is contained in a layer constituting the dielectric layer can be considered. The printed wiring board obtained by the manufacturing method which concerns on this invention becomes a thing characterized by the point that the circuit of an outer layer will be embedded in the insulation resin layer.

<Manufacturing Method 1>

Here, the manufacturing method which can be said to be the most basic among the manufacturing methods of the printed wiring board which concerns on this invention is demonstrated. This manufacturing method is equipped with each process of A) and B) demonstrated below, referring FIG. 1 thru | or FIG. Here, although described once again, although the processing flow is shown in the schematic diagram observed from the cross section, the thickness of each layer does not correspond with a real product so that description is easy to understand.

Process A): First, process A) is demonstrated using FIGS. In a word, this process forms the circuit sheet S with an insulating layer by etching and forming a circuit by the copper foil layer 3 of the copper foil 2 with an insulating layer. The copper foil with insulation layer 2 used in this process has a cross-sectional layer structure as shown in FIG. 5 (8), and the surface roughness which the adhesive surface of the copper foil has on one surface of the copper foil. A cured resin layer 4 having a thickness of 0.5 μm to 10 μm thicker than the value of (Rz) is provided, and the semi-cured resin layer 6 including the skeleton 5 is provided on the cured resin layer 4. will be. Using this copper foil with an insulating layer, an etching resist layer R is formed on the copper foil layer as shown in Fig. 6 (9), and the circuit pattern is exposed as shown in Fig. 6 (10). And developing, etching the copper foil layer 3 to form a circuit C ₁ , as shown in FIG. 7 (11), and etching etching layer R as shown in FIG. 7 (12). By peeling, the circuit sheet S with an insulating layer is formed.

The copper foil with insulation layer 2 used here is a shape which contact | connects the copper foil surface, is provided with the cured resin layer 4 of predetermined thickness in one surface, and the radius which contains frame | skeleton 5 on the cured resin layer 4 The resin layer 6 is provided. Here, the characteristic is that the thickness of the cured resin layer 4 is 0.5 µm to 10 µm thicker than the value of the surface roughness Rz of the adhesive surface of the copper foil. This thickness is the converted thickness at the time of thinking that the cured resin layer was formed in a perfect plane. The lower limit value (the value of the surface roughness (Rz) of the adhesive surface of the copper foil + 0.5) 탆 thickness completely covers the unevenness of the rough surface of the copper foil, and also adds an etching solution to the copper foil layer to perform etching. In consideration of safety for functioning as a barrier of the semi-cured resin at the time. On the other hand, the upper limit value (the value of the surface roughness (Rz) of the adhesive surface of copper foil + 10) µm or less will be described later in the description of the hot forming press step, but this cured resin layer is a circuit at the time of press molding. It is to be of a thickness and material that can be pressed and pierced by hereinafter (hereinafter referred to as impulse). Therefore, it is determined in consideration of the fact that the thickness of copper foil used for a general rigid board is 9 micrometers or more. Therefore, when it exceeds 10 micrometers, the hardening of the hardening resin layer 4 by a circuit will become difficult.

Although the thickness of the hardening resin layer 4 demonstrated above has a restriction | limiting, there is no restriction | limiting in particular about the thickness of the semi-hardened resin layer 6 provided on the hardening resin layer. However, since the circuit becomes a substantially buried layer during hot forming press work, if the thickness is arbitrarily adjusted according to the substrate design, in consideration of the necessity of having a sufficient thickness to secure the interlayer insulation so as not to degrade the crosstalk characteristics. do. In copper foil with an insulating layer, the cured resin layer 4 and the semi-cured resin layer 6 are collectively referred to as an insulating layer.

Here, the manufacture of the copper foil with an insulating layer used by this invention is demonstrated using FIGS. As shown in FIG. 1 (1), a thermosetting resin solution is applied to one surface of the copper foil layer 3 to form a coating film S ₁ , and preferably, dried as shown in FIG. As shown in FIG. 2 (3), this is placed in a heating furnace 20 (in the drawing, when the heater 21 is dried) and heat-treated to harden to form a cured resin layer 4. .

Then, as shown in FIG. 3 (4), a thermosetting resin solution is applied onto the cured resin layer 4 to form a coating film S ₂ , and as shown in FIG. 3 (5), in a semi-cured state. Make. Thereafter, the skeleton 5 is placed on the semi-finished coating film S ₂ in the first step in the order shown in FIG. 4 (6), and the second step in FIG. As shown in FIG. 4, the skeleton 5 is pressed against the semi-cured coating film S ₂ (FIG. 4 schematically shows the form of pressing using the heating roller 22). To the final form.

In addition, as shown in Fig. 5 (7), heated to 20 by heating in was re-fluidizing the constituent resin of the coating layer (S ₂₎ of a semi-cured state, the skeleton material (5, and non-woven fabric or woven fabric it Permeate) and exude to the opposite side and cover the nonwoven or woven fabric with the resin of thermosetting resin. When the operation in the furnace is completed, it is immediately taken out of the furnace, and forcedly cooled by using an air blower 23 as shown in FIG. The maintenance of the image state is ensured. As described above, the copper foil with an insulating layer having an insulating layer made of the semi-cured resin layer 6 including the cured resin layer 4 and the skeleton 5 on one surface of the copper foil is obtained.

Here, the copper foil which comprises the copper foil layer 3 is not specifically limited to manufacturing methods, such as the rolled copper foil obtained by rolling, the electrolytic copper foil obtained by electrolysis, and should just be copper foil used for the electronic material use of a printed wiring board. And this copper foil is described as a concept including the copper foil with a carrier film. The copper foil with a carrier film has a carrier film on the opposite side of the adhesive surface of the copper foil, and is pressed to form a copper foil laminated plate with the carrier film attached thereto, and then the carrier film is removed to be used as a normal copper foil laminated plate. will be. The advantage of using a copper foil with a carrier film is that it is easy to handle thin copper foils such as 9 μm thick, and prevents foreign matters from adhering to the copper foil surface which may occur during press processing and contamination, thereby protecting the copper foil surface from damage until immediately before etching processing. It can be done.

In general, an epoxy resin is used for the resin constituting the curable resin 4. This is because it is widely used in printed wiring board applications. Therefore, if the resin constituting the cured resin layer 4 is a resin having thermosetting properties and can be used for printed wiring boards in the fields of electric and electronic materials, no particular limitation is necessary. The curable resin layer 4 generally employs a method of applying a thermosetting resin solution made of a liquid phase to a copper foil surface using a solvent, but it is also possible to employ a method of laminating a semi-cured resin film as if it were laminated. Do. When making a thermosetting resin solution using a solvent, an epoxy resin, a hardening | curing agent, and a hardening accelerator are mix | blended, for example, viscosity adjustment is carried out using solvents, such as methyl ethyl ketone, and is used. As long as the thickness of the cured resin layer 4 is in the range of 0.5 µm to 10 µm thicker than the surface roughness Rz of the adhesive surface of the copper foil, the curing method and the curing conditions need to be particularly limited. none.

Moreover, the thermosetting resin of the same concept as the hardening resin layer 4 mentioned above, and the skeleton material 5 mentioned below are used also for resin which comprises the semi-hardened resin layer 6. However, the resin which comprises the semi-hardened resin layer 6 and the resin composition which comprises the hardening resin layer 4 do not necessarily need to be the same. Here, the manufacturing method of the semi-cured resin layer 6 shown in FIGS. 3 to 5 will be described in detail complementarily. First, the thermosetting resin solution is apply | coated on the cured resin layer 4 formed in the copper foil surface, and the organic solvent component is removed. Subsequently, a skeleton 5 such as a nonwoven fabric or a woven fabric described below is placed, and the thermosetting resin solution is infiltrated into the skeleton 5 to bleed resin to the opposite side of the skeleton. Then, drying is performed without curing, and the semi-cured resin layer 6 including the skeleton 5 is formed on the cured resin layer 4.

The coating thickness of the thermosetting resin solution at this time is determined in consideration of the thickness of the nonwoven fabric or woven fabric 5 described below. It is preferable to make thickness of X-40 micrometers-X-3 micrometers with respect to the semi-hardened resin layer thickness (Xmicrometer) to form. For example, in order to make thickness of a semi-hardened resin layer into 100 micrometers, it is set as the coating film thickness of 100-3 = 97 micrometers from 100-40 = 60 micrometers, and liquid resin is apply | coated to the copper foil surface. By doing in this way, formation of the semi-hardened resin layer 6 of desired thickness on the surface of the hardening resin layer 4 is attained. When the thickness of the coating film is less than X-40 µm, sufficient adhesion between the finally obtained semi-cured resin layer and the substrate to be attached is not obtained, and even when the thickness of the coating film is greater than X-3 µm, the substrate to be attached with the semi-cured resin layer The effect of improving the adhesiveness with will not increase.

Then, on the coating film S ₂ of the thermosetting resin solution, the frame member 5 (non-woven fabric or woven fabric) is placed, and the constituent resin component of the coating film S ₂ forms the glass fiber constituting the skeleton member 5 or The copper foil 2 with an insulating layer is obtained by making it penetrate using the capillary phenomenon of organic fiber, letting out to the other side of the frame | skeleton 5, and completely covering the surface of the frame | skeleton 5. It is preferable to use what does not decompose | dissolve or melt | dissolve at the soldering tank temperature (about 260 degreeC) for organic fiber here, It is preferable to use any of aramid, wholly aromatic polyester, and PBO (polyparaphenylene benzobisoxazole). desirable.

At this time, in the process shown in FIG. 3 to FIG. 5, in consideration of the following points, it is preferable to impregnate the nonwoven fabric or the woven fabric 5 and to coat the resin of the nonwoven fabric or the woven fabric 5. The coating film of the thermosetting resin solution contains a large amount of an organic solvent. Therefore, if the skeleton 5 is placed on its surface without completely removing the solvent and the following steps are carried out, the fibers of the nonwoven fabric or woven fabric of the skeleton 5 are finally dried when semi-cured. Bubbles tend to form in trapped form. Therefore, as provided with the process of FIG. 3 (5), it is preferable to remove a fixed amount of solvent in order to prevent foaming before placing the skeleton 5 on the coating film surface. The removal of the solvent may be carried out simply by drying by ventilation or by heating to a temperature range below the curing temperature.

Before placing the skeleton material 5, the resin component of the coating film is made into a semi-cured state, and when the skeleton material is placed in the semi-cured coating film, there is no gap between the coating film and the skeleton material. As shown in Fig. 4 (6), it is preferable to press-fit the skeleton to the coating film. Then, in order to reflow the semi-cured coating film resin as shown in FIG. 5 (7), heating is performed at a temperature lower than the curing temperature, and the capillary phenomenon of the glass fibers or aramid fibers constituting the skeleton 5 is applied. Infiltrate by using.

It is preferable to use the nonwoven fabric or woven fabric which used glass fiber and aramid fiber for the skeletal material 5 here. In either case, the printed wiring board is used for a long time and is a highly reliable material. However, the material of a nonwoven fabric or a woven fabric is not specifically limited, What is necessary is just to be usable for a printed wiring board use, and just to have sufficient mechanical characteristics. In order to improve the wettability with resin of the surface, the fiber which comprises the nonwoven fabric and woven fabric used here is preferably subjected to a silane coupling agent treatment. The silane coupling agent at this time may use silane coupling agents, such as an amino type and an epoxy type, according to the purpose of use.

In addition, although there is no restriction | limiting in particular also in the thickness of this frame | skeleton 5, If the manufacturing method of the copper foil with an insulating layer like this invention is employ | adopted, the thin nonwoven fabric or woven fabric of 50 micrometers or less of thickness which was impossible to use conventionally is used. It becomes possible. Conventionally, a skeletal material is immersed in a resin varnish to be impregnated, lifted into a drying tower, dried in a semi-cured state, and a prepreg is adopted. A thin nonwoven fabric having a thickness of 50 µm or less or a woven fabric having a thickness of 20 µm or less is employed. Since the mechanical strength was weak, the defect which broke and broke immediately generate | occur | produced. By the way, if the manufacturing method of the copper foil with an insulating layer which concerns on this invention is employ | adopted, even if it uses the thin nonwoven fabric of 50 micrometers or less in thickness, or the woven fabric of 20 micrometers or less in thickness, it will not be broken or damaged. Since such a thin skeleton material can be used, the printed wiring board obtained by the manufacturing method according to the present invention exhibits very good laser drilling processing performance, and can secure the minimum strength required for the printed wiring board. It is also possible to meet the requirements of forming a fine pitch circuit.

Thus, the copper foil with an insulating layer used by the manufacturing method which concerns on this invention is obtained. And as shown in FIG.6 (9), the etching resist layer R is provided in the surface of the copper foil layer 3 of this copper foil with insulation layer 2, and it shows in FIG. The circuit pattern as described above is exposed and developed. Then, as shown in Fig. 7 (11), the copper is etched from the surface of the copper foil layer side, and as shown in Fig. 7 (12), the etching resist is peeled off to form a circuit pattern. This is the circuit sheet 7 with an insulating layer. In this circuit etching, when an etching solution is added from the copper foil layer side, the cured resin layer 4 becomes a barrier and the semi-cured resin layer 6 is not damaged. However, when etching liquid, a resist releasing agent, etc. return to the semi-cured resin layer 6 side, it is preferable to use protective films, such as PET film and a polyethylene film, on the surface of the semi-hardened resin layer 6.

Process B): The base material to which the semi-hardened resin layer 6 of the circuit sheet 7 with an insulating layer obtained as mentioned above is shown to FIG. 8 (13) (Inner layer circuit C in a figure). ₂ ) an inner layer core material 24 having a core) is used. At the time of hot press molding, about 170-180 degreeC heating is performed and it pressurizes. By this pressurization, the circuit is pressed into the semi-cured resin layer side while generating a crack in the cured resin layer below it. In the present invention, this phenomenon is called impingement. At the time of filling, a crack is generated in the cured resin layer 4, and the thermosetting resin of the semi-cured resin layer 6, which is starting to reflow from the crack, is ejected through the side wall of the circuit, thereby completely insulating the circuit. It is embedded in the ground layer, and an insulating layer in which the cured resin layer 4 and the semi-cured resin layer 6 are integrated is formed. As described above, when the hot pressing step is completed, the printed wiring board 1a having the circuit C ₁ embedded in the insulating resin layer according to the present invention shown in Fig. 8 (14) is obtained.

<Method of manufacturing printed wiring board for capacitor>

Since the following steps have a part in common with the manufacturing method of the above-described printed wiring board, the description of the common parts is omitted in order to avoid overlapping description, and referring to FIGS. 9 to 11, the capacitor printed wiring board 1b. Only the characteristic parts in the manufacturing method of the process will be described in order.

Step A): In this step, one surface of the copper foil 3 is provided with a cured resin layer that is 0.5 µm to 10 µm thicker than the value of the surface roughness Rz of the adhesive surface of the copper foil, and the cured resin layer Using a copper foil with an insulating layer having a semi-cured resin layer containing a skeleton material thereon, an etching resist layer is formed on the copper foil surface, the capacitor circuit pattern is exposed, developed, and the copper foil surface is etched to form an electrode on one side. The capacitor circuit to be used is formed, and the resist layer is peeled off to form a capacitor circuit sheet with an insulating layer. Therefore, since the circuit to be formed differs only from the fact that the circuit to be formed is a circuit including an electrode shape on one side which becomes the upper electrode or the lower electrode of the capacitor circuit, a detailed description of this process is omitted. .

Step B): In this step, the hot foil is formed by contacting and superimposing the semi-cured resin layer of the capacitor circuit sheet with the insulating layer to be bonded to it, so that the copper foil of the circuit part impregnates the cured resin layer to the semi-cured resin layer. It is made of the printed wiring board provided with the capacitor circuit embedded in the insulation resin layer. Accordingly, a printed wiring board in which a circuit including an electrode shape on one side, which becomes an upper electrode or a lower electrode of a circuit for a capacitor, is embedded in a hot forming press, and there is no difference from the hot forming press process of step B) described above. If it is easily understood, detailed description of this process is omitted.

Step C): In this step, as shown in FIG. 9 (1), the dielectric layer of the copper foil with dielectric layer 10 on the surface of the embedded circuit C ₁ of the printed wiring board 1a having the capacitor pattern circuit ( 11) Touch and overlap the faces. And by hot press molding, the copper foil laminated board 12 in which the copper foil layer is located in an outer layer as shown to Fig.9 (2) is made. The copper foil with a dielectric layer 10 is provided with the resin layer which comprises the dielectric layer 11 or the dielectric filler when the capacitor circuit is formed in one surface of copper foil. Therefore, the layer structure seen from the cross section has a very simple structure, as can be seen from (1) of FIG. 9 to 11, the description is not made until the dielectric layer is shown in the dielectric layer. The performance as a capacitor depends on the type of resin and dielectric filler constituting the dielectric layer and the thickness of the dielectric layer at this time.

In the present invention, since the surface of the printed wiring board including the capacitor circuit manufactured in step B) is flat and the circuit C ₁ part is not protruding, it is not necessary to consider the spread of the resin component in the gap between circuits. Even if a resin having a small resin flow is used for the dielectric layer, voids such as voids do not occur and good adhesion can be obtained. In addition, since the surface of this printed wiring board is flat, it is easy to secure the thickness precision of the dielectric layer, the thickness of the dielectric layer is easy, and the capacitor circuit with large capacitance can be formed.

Here, the resin composition which comprises the dielectric layer 11 of the copper foil 10 with a dielectric layer is demonstrated. In principle, the resin composition is not particularly limited, and the material used may be appropriately selected appropriately in consideration of design quality such as capacitance required for a capacitor circuit. However, since the surface of the printed wiring board to be pasted is flat and free of unevenness, it is preferable to adopt a resin composition excellent in adhesion from the viewpoint of preventing interfacial peeling as much as possible. Especially preferable is resin composition as demonstrated below.

Preferred resin compositions for constituting the dielectric layer are simply composed of an epoxy resin, a curing agent, an aromatic polyamide resin polymer soluble in a solvent, and a curing accelerator added in an appropriate amount as necessary.

"Epoxy resin" as used herein has two or more epoxy groups in a molecule and can be used without particular problem as long as it can be used for electric and electronic material applications. Among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin, brominated epoxy resin, and glycidylamine It is preferable to use 1 type (s) or 2 or more types selected from the group of a type | mold epoxy resin, and to mix and use.

This epoxy resin is the main component of the resin composition, and is used in a blending ratio of 20 parts by weight to 80 parts by weight. However, it is considered to contain the hardening | curing agent described below here. Therefore, when this epoxy resin in the state containing a hardening | curing agent is less than 20 weight part, it does not fully exhibit thermosetting property, cannot fully exhibit the function as a binder with base resin, and adhesiveness with copper foil, and when it exceeds 80 weight part The viscosity of the solution becomes so high that application of a uniform thickness to the surface of the copper foil becomes difficult, and the balance with the amount of the aromatic polyamide resin polymer to be described later is broken, and sufficient toughness can be obtained after curing. There will be no.

The "curing agent" of the epoxy resin is amines such as dicyandiamide, imidazoles, aromatic amines, phenols such as bisphenol A and brominated bisphenol A, novolacs such as phenol novolak resins and cresol novolak resins, phthalic anhydride, and the like. Acid anhydride. Since the amount of the curing agent added to the epoxy resin is naturally derived from the respective equivalents, it is considered that there is no necessity of explicitly specifying the blending ratio. Therefore, in this invention, the addition amount of a hardening | curing agent is not specifically limited.

Next, the "aromatic polyamide resin polymer" is obtained by reacting an aromatic polyamide resin with a rubbery resin. Here, an aromatic polyamide resin is synthesize | combined by polycondensation of aromatic diamine and dicarboxylic acid. 4,4'- diamino diphenylmethane, 3,3'- diamino diphenyl sulfone, m-xylenediamine, 3,3'- oxydianiline etc. are used for aromatic diamine at this time. Phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and the like are used for the dicarboxylic acid.

The rubbery resin reacted with the aromatic polyamide resin is described as a concept including natural rubber and synthetic rubber. The latter synthetic rubbers include styrene-butadiene rubber, butadiene rubber, butyl rubber, ethylene-propylene rubber, and the like. have. In addition, when securing the heat resistance of the dielectric layer to be formed, it is also useful to select and use synthetic rubber having heat resistance such as nitrile rubber, chloroprene rubber, silicone rubber, urethane rubber and the like. Regarding these rubbery resins, in order to produce a copolymer by reacting with an aromatic polyamide resin, it is preferable to provide various functional groups at both ends. In particular, it is useful to use CTBN (carboxyl terminal butadienenitrile).

It is preferable to use the aromatic polyamide resin and the rubbery resin which comprise the aromatic polyamide resin polymer in a mixture of 25 parts by weight to 75 parts by weight of the aromatic polyamide resin, and the rest of the rubbery resin. When the aromatic polyamide resin is less than 25 parts by weight, the abundance ratio of the rubber component becomes too large to reduce heat resistance. On the other hand, when the aromatic polyamide resin is more than 75 parts by weight, the abundance ratio of the aromatic polyamide resin becomes so large that the hardness after curing becomes too high and becomes vulnerable. . This aromatic polyamide resin polymer is used for the purpose of not damaging under etching etc. by etching liquid, when etching the copper foil after processing into the copper clad laminated board.

In this aromatic polyamide resin polymer, the property of soluble in a solvent is calculated | required first. This aromatic polyamide resin polymer is used in the compounding ratio of 20 weight part-80 weight part. When aromatic polyamide resin polymer is less than 20 weight part, it hardens | cures too much in general press conditions which manufacture copper clad laminated board, and becomes easy to produce microcracks on the board | substrate surface. On the other hand, even if the aromatic polyamide resin polymer is added in excess of 80 parts by weight, there is no particular problem. However, the strength after curing is not improved even if the aromatic polyamide resin polymer is added in excess of 80 parts by weight. Therefore, considering economical efficiency, it can be said that 80 weight part is an upper limit.

The "hardening accelerator added with an appropriate amount as needed" is a tertiary amine, imidazole, urea-type hardening accelerator, etc. In this invention, the compounding ratio of this hardening accelerator is not specifically limited. This is because the curing accelerator may be selected arbitrarily by the manufacturer in consideration of the production conditions in the copper foil laminated sheet manufacturing process and the like.

Next, the dielectric filler used for forming the dielectric layer 11 will be described. The dielectric filler is mixed in the resin component used to form the dielectric layer described above, dispersed in the dielectric layer, and used to increase the capacitor capacitance when finally processed into a capacitor shape. A dielectric filler is _{BaTiO 3, SrTiO 3, Pb (} Zr-Ti) O 3 ( known as PZT), PbLaTiO ₃ · PbLaZrO (collectively _{PLZT), SrBi 2 Ta 2 O} 9 ( usually SBT), etc. of the perovskite (perovskite It is preferable to use a dielectric powder of a composite oxide having a structure.

The powder characteristics of the dielectric filler are preferably in the range of 0.1 to 1.0 mu m in particle size. The particle size here is impossible to use because the granules form a certain secondary agglomerated state, so the precision is inferior in indirect measurement such as guessing the average particle diameter from measured values such as laser diffraction scattering particle size distribution method or BET method. In this case, the dielectric filler is directly observed with a scanning electron microscope (SEM), and the mean particle size of the SEM image can be analyzed. In this specification, the particle size at this time is denoted by D _IA . Image analysis of the dielectric filler powder observed using a scanning electron microscope (SEM) in the present specification was carried out using an Asahi Engineering Co., Ltd. IP-1000PC, with a roundness threshold of 10 and an overlapped degree. extend value) 20, the circular particle analysis was performed, and the average particle diameter D _IA was calculated | required.

Moreover, the weight cumulative particle diameter D ₅₀ by the laser diffraction scattering particle size distribution method is 0.2-2.0 micrometers, and is represented by D ₅₀ / D _IA using the weight cumulative particle diameter D ₅₀ and the average particle diameter D _IA obtained by image analysis. It is required that the dielectric granules have a substantially spherical perovskite structure having a cohesion value of 4.5 or less.

Laser diffraction scattering type particle size by weight cumulative particle diameter of the distribution measuring method D ₅₀ is, would that particle size of the weight accumulation of 50% is obtained by using a laser diffraction scattering type particle size distribution measuring method, the smaller the value of the weight-cumulative particle diameter D ₅₀ Dielectric In the particle size distribution of the filler powder, the proportion of the fine powder is large. In this invention, this value is required to be 0.2 micrometer-2.0 micrometers. In other words, when _the value of the weight cumulative particle diameter D5 _{0 is} less than 0.2 µm, the progress of aggregation is remarkable, regardless of the dielectric filler granules employing any manufacturing method, so that the degree of aggregation described below cannot be satisfied. On the other hand, when the value of the weight cumulative particle diameter D ₅₀ exceeds 2.0 µm, the use of the printed wiring board, which is the object of the present invention, as a dielectric filler for forming an embedded capacitor layer becomes impossible. That is, the dielectric layer of the double-side copper-clad laminate used to form the capacitor layer is usually 10 µm to 50 µm thick, and 2.0 µm is the upper limit in order to uniformly disperse the dielectric filler.

Here, in the present invention, the measurement of the weight cumulative particle diameter D ₅₀ is performed by mixing and dispersing the dielectric filler powder in methyl ethyl ketone, and dispersing the solution in a laser diffraction scattering type particle size distribution analyzer Micro Trac HRA 9320-X100 type (Nikiso It measured by putting into the circulator of Co., Ltd. product.

Although the concept of agglomeration degree is used here, it adopts for the following reasons. That is, it is thought that the value of the weight cumulative particle diameter D ₅₀ obtained using the laser diffraction scattering particle size distribution measurement method did not actually directly observe the diameter of each powder. This is because the pulverization constituting most of the dielectric pulverization is not a so-called monodisperse pulverization in which individual particles are completely separated, but rather a plurality of pulverization aggregated together. This is because the laser diffraction scattering particle size distribution method recognizes the aggregated granules as one particle (aggregated particle) and calculates the weight cumulative particle size.

On the other hand, since the average particle diameter D _IA obtained by image-processing the observation image of the dielectric granules observed using the scanning electron microscope (SEM) is obtained directly from the SEM observation image, the primary particles are certainly recognized, It does not reflect the presence of the aggregated state of.

Considering the above, the inventors decided to accept the value calculated as D ₅₀ / D _IA as the degree of cohesion by using the weight cumulative particle diameter D ₅₀ of the laser diffraction scattering particle size distribution method and the average particle diameter D _IA obtained by image analysis. . That is, assuming that the values of D ₅₀ and D _IA can be measured with the same precision in dielectric separation of the same lot, and the above-mentioned theory is assumed, the value of D ₅₀ reflecting the measured value that is in the aggregate state is It can be considered that the value is larger than the value of D _IA (the same result is obtained even in the measurement of reality).

At this time, the value of D ₅₀ is, if the aggregation state of the powder of the dielectric filler powder completely eopeojindago, gamyeo close to the value of the unlimited D _IA, the value of the degree of compaction of D ₅₀ / D _IA is close to 1. In the stage where the degree of agglomeration is 1, it can be said that the monodisperse powder has completely lost the aggregated state of the powder. However, in reality, the degree of aggregation may be less than one. In the case of the perfect sphere theoretically considered, the value is not less than 1, but since it is not a perfect sphere in reality, a cohesion value of less than 1 is obtained.

In the present invention, the degree of aggregation of the dielectric filler powder is required to be 4.5 or less. If the degree of agglomeration exceeds 4.5, the level of agglomeration of the granules of the dielectric filler becomes so high that it becomes difficult to uniformly mix with the above-mentioned binder resin.

Even if any one of the alkoxide method, the hydrothermal synthesis method, and the oxalate method is used as the method for producing the dielectric filler powder, a uniform aggregation state is inevitably formed, and thus, the dielectric filler powder that does not satisfy the above-mentioned degree of aggregation may occur. have. In particular, in the hydrothermal synthesis method, which is a wet method, formation of agglomerated states tends to occur. Therefore, by performing the disintegration process of separating the aggregated powder into single granules, it is possible to set the aggregated state of the dielectric filler granules to the above-mentioned cohesion range.

For the purpose of simply dismantling, various means such as high energy ball mills, high-speed conductor collision type airflow grinders, impact grinders, gauge mills, media stirring mills, and high-pressure grinders are available. Available. By the way, in order to ensure the mixing property and dispersibility of dielectric filler powder and binder resin, the viscosity reduction as a dielectric filler containing resin solution mentioned below must be considered. In order to reduce the viscosity of the dielectric filler-containing resin solution, it is required that the specific surface area of the dielectric filler powder is small and smooth. Therefore, disassembly should not be a disassembly technique such as, if possible, that damages the surface of the powder during disassembly and increases its specific surface area.

Based on these perceptions, the inventors have diligently studied and found that both methods are effective. Common to both methods is to minimize the separation of the dielectric filler powder from contact with parts of the inner wall of the apparatus, the stirring blades, the grinding media, etc., and to cause the mutual collision of the agglomerated powders, thereby providing sufficient separation. It's a possible way. That is, contact with parts of the inner wall of the apparatus, agitating blades, grinding media, etc. is to prevent the surface of the powder, increase the surface roughness, and deteriorate the sphericity, thereby preventing this. . Therefore, by causing collision of sufficient powders, it is possible to employ a method capable of releasing the powders in the aggregated state and at the same time smoothing the powder surface by the collisions of the powders.

One is to dissociate the dielectric filler powder in agglomerated state using a jet mill. The term "jet mill" herein refers to the use of a high speed air stream of air to insert dielectric filler powder in the air stream, and to dissociate the powder particles in the high speed air stream to perform the disassembly operation.

Moreover, the slurry which disperse | distributed the dielectric filler powder in aggregate in the solvent which does not break the stoichiometry is disaggregated using the fluid mill which uses centrifugal force. By using the "fluid mill using centrifugal force" here, the slurry is flowed at high speed so as to draw a circumferential trajectory, and the agglomeration work is carried out by colliding the granules aggregated by the centrifugal force generated at this time in a solvent. By doing in this way, the dielectric filler powder in which the disassembly operation was completed is obtained by washing | cleaning, filtration, and drying of the slurry which completed the disassembly operation. By the above-described method, the degree of cohesion can be adjusted and the surface of the powder of the dielectric filler powder can be smoothed.

The thermosetting resin and the dielectric filler described above are mixed to form a dielectric filler-containing resin for forming a capacitor layer of a printed wiring board. In this case, the mixing ratio of the thermosetting resin and the dielectric filler is preferably 75 wt% to 85 wt% of the dielectric filler, and the remainder is the thermosetting resin. When the content of the dielectric filler is less than 75 wt%, the dielectric constant 20 currently required in the market cannot be satisfied, and when the content of the dielectric filler exceeds 85 wt%, the content of the thermosetting resin is less than 15 wt%, and the dielectric filler is contained. The adhesiveness of resin and the copper foil stuck to it is impaired, and it becomes difficult to manufacture the copper foil laminated board which satisfy | fills the required characteristic for printed wiring board manufacture.

By using the dielectric filler-containing resin described above, if the dielectric layer of the capacitor layer of the printed wiring board is formed, the dielectric layer can be thinned with sufficient film thickness uniformity, resulting in a very good high air capacity. It becomes a capacitor circuit.

Step D): In this step, an etching resist layer is formed on the outer copper foil 3, the capacitor circuit pattern is exposed and developed, the copper foil surface is etched to form the capacitor circuit C ₃ , and the resist layer is peeled off. The capacitor circuit C ₃ serving as the electrode on the other side is formed, and the printed circuit board is provided with the capacitor circuit. 10 and 11 illustrate this process.

That is, the circuit containing the electrode shape of the other side used as the upper electrode or lower electrode of the capacitor circuit formed in the above-mentioned process A) is processed similarly to etching the outer layer copper foil of a multilayer printed wiring board. Therefore, those skilled in the art can easily understand, and furthermore, since there are many descriptions and overlapping portions of step A), detailed description of this step is omitted.

In the description of the manufacturing method described above, an image in which both surfaces are laminated in the drawings is shown, but those skilled in the art are applicable to printed wiring boards according to all layer configurations including one side, two sides, and three or more multilayer boards.

The manufacturing method of the printed wiring board demonstrated above is a method which can manufacture the printed wiring board which has a circuit arrange | positioned in the insulating resin layer very efficiently, The surface of the obtained printed wiring board is very flat, and the skeleton material in an insulating layer Since it is possible to make the thickness very thin, the laser drilling processability is excellent, the processing efficiency by the low-power carbon dioxide laser can be drastically increased, and it is possible to meet the requirements of high density wiring and high density mounting.

In addition, by adopting a method of manufacturing a printed wiring board having a capacitor circuit embedded in an insulating resin layer according to the present invention, since a dielectric layer is attached to the surface of a flat printed wiring board, even if the dielectric layer thickness of the capacitor circuit is designed to be thin , Very high thickness precision can be obtained.

EMBODIMENT OF THE INVENTION Hereinafter, preferable embodiment of the manufacturing method of the printed wiring board which concerns on this invention is described.

<Example 1>

In this embodiment, according to the flow shown in FIGS. 1-5, the copper foil with an insulating layer was formed using the electrolytic copper foil 3 whose formula thickness is 12 micrometers, and the surface roughness Rz of a rough surface is 3.0 micrometers. ).

First, the epoxy resin composition used for formation of the cured resin layer 4 and the semi-hardened resin layer 6 was adjusted. Here, 30 weight part of bisphenol-A epoxy resin (brand name: YD-128, product made by Totokasei Co., Ltd.), o-cresol type epoxy resin (brand name: ESCN-195XL80, Sumitomo Chemical Co., Ltd. make) as resin. 50 parts by weight of 16% by weight of dicyandiamide (4 parts by weight of dicyandiamide) in the form of a dimethylformaldehyde solution having a solid content of 25% as an epoxy resin curing agent and 2-ethyl4-methylimidazole (as a curing accelerator) Product Name: Casol 2E4MZ, manufactured by Shikoku Chemical Co., Ltd., was dissolved in 0.1 part by weight of a mixed solvent of methyl ethyl ketone and dimethyl formaldehyde (mixing ratio: methyl ethyl ketone / dimethyl formaldehyde = 4/6) to give 60% solids. Epoxy resin composition was used, and this was used.

Isolated producing a copper foil layer: according to the flow shown in Figs. 1 and 2, in the surface roughness by uniformly applied to (Rz = 2.0㎛) at room temperature in the epoxy resin composition of the electrolytic copper foil 3 of the formula thickness 12㎛ It was left to stand for 30 minutes, the air of 150 degreeC was blown for 2 minutes using a hot air dryer, the fixed amount of solvent was removed, and the hardening process was performed for 60 minutes at the temperature of 170 degreeC, and the hardening resin layer 4 was formed. The coating amount of the epoxy resin composition at this time was 8 micrometers thicker than the value of the surface roughness (Rz) which the adhesive surface of the copper foil had as a film thickness after hardening.

Next, according to the flow shown in FIG. 3 inside FIG. 5, the semi-hardened resin layer 6 was formed in the surface of the hardening resin layer 4. As shown in FIG. The epoxy resin composition was uniformly coated on the surface of the cured resin layer 4 and allowed to stand for 30 minutes at room temperature, followed by blowing hot air at 150 ° C. for 2 minutes using a hot air dryer, thereby obtaining a film thickness of a semi-cured state of 10 μm thickness. Formed. And the aramid fiber nonwoven fabric with a formal thickness of 50 micrometers was stuck on it as the skeleton material 5. This paste was heated at 150 ° C. by superimposing the nonwoven fabric on the surface of semi-cured coating film S ₂ , and was heated at a speed of 20 cm / min between heating rollers 22 to apply a lamination pressure of 9 kg / cm ² . It was done by passing through. As a result, the total thickness of the coating film S ₂ and the skeleton 5 in the stuck state was an average of 55 µm.

When the bonding of the framework 5 is completed as described above, the semi-cured resin of the coating film S ₂ is reflowed by holding it for 1 minute in an atmosphere of 150 ° C. using a hot air dryer to obtain the constituent resin component. capillary action of the aramid fibers constituting the skeleton material (5) and penetrating it for this, and to come out soaked far side opposite to the contact surface between the coating layer (S ₂₎ of the backbone member (5), a surface of the skeletal material 5 The semi-hardened resin layer 6 was formed by completely covering and drying it, and the copper foil 2 with an insulating layer shown in (8) of FIG. 5 was obtained by forcibly temperature-falling with the air blow 23. At this time, the total thickness after drying of the semi-hardened resin layer 6 was 42 micrometers, and PET film (not shown in figure) was laminated and stuck to this semi-hardened resin layer 6.

Manufacture of a circuit sheet with an insulating layer : According to the flow shown to FIG. 6 and FIG. 7, the dry film is laminated on the surface of the copper foil layer 3 of the said copper foil with an insulating layer 2, and the etching resist layer R is performed. The dry film was left only to the copper foil surface used as a circuit by forming and exposing the film for exposure on the surface of the etching resist layer R, and developing. Subsequently, the copper chloride etching solution was added only to the copper foil surface to perform circuit etching, and the peeling of the resist and the peeling of the PET film of the semi-cured resin layer 6 were carried out, and as shown in FIG. _The circuit sheet 7 with an insulation layer like ₁ ) was obtained.

Hot press forming: And, according to the flow shown in Figure 8, the insulating layer having a circuit sheet 7 and the inner layer circuit (C _2), the inner surface of a core member 24 (having a thickness of 0.6mm, formed in the copper foil Four layers of multilayer printed wiring board 1a were manufactured using FR-4 material of 35 micrometers in thickness. That is, as shown in (13) of FIG. 8, the circuit sheet 7 with an insulating layer is formed on each of the outer side surfaces of the inner core material 24, and the insulating layer is an inner core material. By laminating and pressing to contact the outer layer surface of (24), the outer layer circuit was embedded in the insulating resin layer to produce a multilayer printed wiring board 1a having a flat surface. The press working conditions at this time were press temperature 180 degreeC, press pressure 20kg / cm <^2> , and hardening time 90 minutes.

<Example 2>

In this embodiment, in accordance with the flow shown in Figs. 9 to 11, by attaching the copper foil 10 with the dielectric layer to be described below, the outer layer of the four-layer multilayer printed wiring board 1a manufactured in Example 1 is Six multilayer printed wiring boards 1b including a capacitor circuit layer were manufactured. Therefore, overlapping description is abbreviate | omitted and it demonstrates from manufacture of the copper foil 10 with a dielectric layer.

Producing a dielectric attached to the copper foil: was first to prepare a resin solution constituting the dielectric layer 11. In preparing this resin solution, it is commercially available as a mixed varnish with o-cresol noborac type epoxy resin (YDCN-704 manufactured by Totokasei Co., Ltd.), aromatic polyamide resin polymer soluble in a solvent, and cyclopentanone as a solvent. BP3225-50P manufactured by Nippon Kayaku Co., Ltd. was used as a raw material. To this mixed varnish, VH-4170 manufactured by Dai Nippon Ink Co., Ltd. and 2E4MZ manufactured by Shikoku Chemical Co., Ltd. as a curing accelerator were added to the phenol resin as a curing agent, and the compounding ratio shown below was obtained. A resin mixture was made.

Resin mixture

 38 parts by weight of o-cresol noborac epoxy resin

50 parts by weight of aromatic polyamide resin polymer

Phenolic resin 18 parts by weight

0.1 part by weight of curing accelerator

The resin mixture was further prepared by adjusting the resin solid content to 30% by weight using methyl ethyl ketone. Then, the resin solution was mixed and dispersed with barium titanate powder, which is a dielectric filler F having the following powder characteristics, to prepare a dielectric filler-containing resin solution having the following composition.

dielectric Of filler Powder characteristics

Average particle diameter (D _IA ) 0.25㎛

Cumulative weight diameter (D ₅₀ ) 0.5㎛

Cohesion (D ₅₀ / D _IA ) 2.0

dielectric  Filler-containing resin solution

Binder Resin Solution 83.3 parts by weight

100 parts by weight of barium titanate powder

The dielectric filler-containing resin solution prepared as described above was applied to the rough surface of the electrolytic copper foil 2 having a thickness of 35 μm by using an edge coater so as to have a predetermined thickness, and then air dried for 5 minutes. After that, drying was performed for 3 minutes in a heating atmosphere at 140 ° C. to form a dielectric layer 11 having a thickness of 20 μm in a semi-cured state.

Fabrication of Printed Wiring Board with Capacitor Circuit : When formation of the dielectric layer 11 is completed, as shown in FIG. 9 (1), the multilayer printed wiring board 1a obtained with the dielectric layer 11 in Example 1 is obtained. It contacted and laminated | stacked on the outer layer surface, and hot-press-molded under the heating condition of 180 degreeC * 60 minutes, and made it into the 6-layer copper-clad laminated board 12 state.

The double-sided copper foil layer 3 of the copper-clad laminate 12 produced as described above is faced, and as shown in FIG. 10 (3), a dry film is attached to both surfaces thereof to form an etching resist layer ( Formed R). Then, as shown in FIG. 10 (3), an etching circuit was formed by exposing and developing a capacitor circuit on the etching resist layer R on both surfaces thereof. After that, as shown in Fig. 11, the circuit is etched with the iron chloride etching solution and the etching resist is peeled off, so that the circuit C ₁ and the circuit C ₃ become upper or lower electrodes, and a capacitor circuit having a dielectric layer therebetween is formed. The equipped printed wiring board 1b was manufactured.

As a result of measuring the relative dielectric constant of the dielectric layer constituting the capacitor circuit, it was found that ε = 20 was very good, and a capacitor having a high capacitance was obtained.

Comparative Example 1

In this comparative example, the same resin as used in Example 1 was uniformly coated on the rough surface of the electrolytic copper foil having a formula thickness of 12 µm, left at room temperature for 30 minutes, and blown with a hot air dryer at 150 ° C. for 5 minutes. By removing a fixed amount of solvent, the resin layer was dried in a semi-cured state, thereby obtaining a copper foil with a resin that does not contain a conventional skeleton material. The coating amount of the epoxy resin composition at this time was 75 micrometers as thickness of the resin layer after drying.

And this copper foil with resin was used instead of the copper foil 1 with the insulating layer of Example 1 mentioned above, and it obtained the circuit sheet with a resin layer in the same manner as Example 1, and obtained four layers by hot press molding with an inner layer core material. The printed wiring board was manufactured. As a result, the semi-hardened resin layer sometimes cracked due to the handling during the circuit forming etching prior to the hot press processing, and even though it was padded with PET film, there was a problem due to the absence of the skeleton material. Could not get

The manufacturing method of the printed wiring board which concerns on this invention can manufacture the printed wiring board which has a circuit arrange | positioned in the insulating resin layer very efficiently. Therefore, a printed wiring board having a very flat surface can be produced with excellent yield, and the printed wiring board can be supplied to the market at low cost. Furthermore, since this printed wiring board can make the frame | skeleton in an insulating layer very thin, it is excellent in laser perforation | workability and also has the intensity | strength required for a board | substrate.

In addition, by adopting a method of manufacturing a printed wiring board having a capacitor circuit embedded in an insulating resin layer according to the present invention, even if the dielectric layer thickness of the capacitor circuit is designed thin, very high thickness precision can be obtained, and the capacitor circuit is provided. It is possible to significantly increase the quality of a printed wiring board.

Claims (6)

A method of manufacturing a printed wiring board having a circuit embedded in an insulating resin layer, comprising the steps A) and B) below. A) The cured resin layer which is 0.5 micrometer-1 micrometer thicker than the value of the surface roughness (Rz) which the adhesive surface of this copper foil has on one surface of copper foil, The semi-hardened resin layer containing a skeleton material on this hardened resin layer A circuit sheet with an insulating layer was formed by forming an etching resist layer on the copper foil surface using the copper foil with an insulating layer, exposing and developing a circuit pattern, etching the copper foil surface to form a circuit, and peeling off the resist layer. To form. B) The hot foil is formed by contacting and superimposing the semi-cured resin layer of the circuit sheet with the insulating layer to be bonded, and the copper foil of the circuit portion blows up the cured resin layer and is embedded in the semi-cured resin layer, and is insulated. The printed wiring board provided with the circuit embedded in the resin layer is formed. A method for manufacturing a printed wiring board having a capacitor circuit embedded in an insulating resin layer, the method comprising the steps A) to D) below. A) The cured resin layer which is 0.5 micrometer-1 micrometer thicker than the value of the surface roughness (Rz) which the adhesive surface of this copper foil has on one surface of copper foil, The semi-hardened resin layer containing a skeleton material on this hardened resin layer Using an copper foil with an insulating layer, an etching resist layer is formed on the copper foil surface, the circuit pattern is exposed and developed, the copper foil surface is etched to form a capacitor circuit that becomes an electrode on one side, and the resist layer is formed. By peeling, the capacitor circuit sheet with an insulating layer is formed. B) By hot press molding by contacting and superimposing the semi-cured resin layer of the circuit sheet with the insulating layer to be pasted, the copper foil of the circuit part impregnates the cured resin layer and is embedded in the semi-cured resin layer, and is embedded in the insulating resin layer. A printed wiring board having a capacitor circuit disposed therein is formed. C) The copper-clad laminated board in which the copper foil layer is located is formed in an outer layer by hot-press molding by contacting and superimposing the resin layer surface of the copper foil with a dielectric layer on the embedded circuit surface of the printed wiring board provided with the said capacitor circuit. D) An etching resist layer is formed on the outer copper foil, the capacitor circuit pattern is exposed and developed, the copper foil surface is etched to form a capacitor circuit, and the resist layer is peeled off to form a capacitor circuit serving as an electrode on the other side. A printed wiring board having a capacitor circuit is formed. The method of claim 1, The frame | skeleton which comprises a semi-hardened resin layer is a nonwoven fabric or a woven fabric, The manufacturing method of the printed wiring board characterized by consisting of glass fiber or organic fiber. The method of claim 2, The frame | skeleton which comprises a semi-hardened resin layer is a nonwoven fabric or a woven fabric, The manufacturing method of the printed wiring board characterized by consisting of glass fiber or organic fiber. The method of claim 2, The resin layer which comprises the copper foil with a dielectric layer contains the dielectric filler, The manufacturing method of the printed wiring board characterized by the above-mentioned. The printed wiring board manufactured by the manufacturing method in any one of Claims 1-5.

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