JP4226981B2 - Printed wiring board manufacturing method and printed wiring board obtained by the manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a copper foil with an insulating layer, a copper foil with an insulating layer obtained by the production method, and a multilayer printed wiring board using the copper foil with an insulating layer.

  The following two demands are always made for printed wiring boards in recent years. For one thing, as electronic devices and electrical products on which printed wiring boards are mounted are becoming lighter, thinner, and lighter, they are required to be thinner and lighter. It is demanded. At the same time, it is common to form a capacitor circuit in the inner layer circuit portion of the multilayer printed wiring board to reduce power consumption and stabilize the supply voltage of electronic devices.

Technical background regarding laser drilling ability : First, a technical background regarding fine pitching will be described. In order to improve the wiring density, it has become common to form a small-diameter via hole using a laser processing method as disclosed in Patent Document 1. However, with the widespread use of laser drilling processing, it has been found that the multilayer printed wiring board manufactured using FR-4 prepreg, which is a conventional glass epoxy base material, is inferior in laser drilling processing on the inner wall surface shape of the via hole. I have done it. The first problem was the presence of glass cloth, which is a skeleton material of the glass epoxy base material. The glass cloth has a weave and the glass itself is inferior in laser processability, so that it was not possible to drill holes with good accuracy.

Japanese Patent Laid-Open No. 11-195853

  Accordingly, the inventors of the present invention supply a prepreg with a resin-coated copper foil in which only a semi-cured resin layer not containing a skeleton material is provided on the surface of the copper foil as disclosed in Patent Document 2. Using the built-up method, it has become possible to produce copper-clad laminates with excellent laser drilling workability and to supply high-quality multilayer printed wiring boards. That is, the resin-coated copper foil is light in weight because it does not contain a skeleton material in its resin layer, and is excellent in laser drilling workability in the sense that the inner wall of the via hole becomes smooth and the blow hole can be eliminated. At the same time, there are the following disadvantages because it does not contain a skeletal material.

International Publication Number WO 97/02728

  That is, the copper clad laminate produced using only the resin-coated copper foil has a problem that the mechanical strength of the resin layer is not sufficient with respect to external forces such as bending, pulling, and impact. And since the copper foil with resin has no reinforcing material, the copper clad laminate manufactured using only the copper foil with resin has a thickness of the insulating layer in the same plane in a system in which the copper circuit density of the inner layer circuit is not uniform. Is extremely fluctuating and difficult to control. The coefficient of thermal expansion as a material is large, and stress is easily generated at an interface with a different material, for example, a copper circuit, which adversely affects reliability. In addition, the copper clad laminate produced using only the resin-coated copper foil has low strength, and various disadvantages are pointed out, such as the sinking of the pads during wire bonding of IC chips and the inability to obtain stable bonding. It was.

  Also in the field of the other prepreg, as disclosed in Patent Document 3, as a method for improving the laser drilling workability while maintaining the mechanical strength described above, a product devised for the skeleton material has been supplied. It was. That is, when glass cloth is used as the skeleton material, it has been said that it is generally inferior in laser drilling workability. Therefore, it has become common to use a so-called non-woven fabric type as a skeletal material without using a woven cloth type. By using a non-woven fabric, the non-uniformity of the cross yarn as seen in the cross-type skeleton material has been improved, and the laser drillability has been greatly improved.

Japanese Patent Laid-Open No. 2003-213019

Technical Background Regarding Printed Wiring Board with Capacitor Circuit: Next, a technical background regarding the capacitor circuit board will be described. When manufacturing a capacitor circuit board using a copper clad laminate, using a double-sided copper clad laminate comprising a so-called double-sided copper foil layer and a dielectric layer located between the copper foil layers, Usually, the copper foil layers on both sides are etched into capacitor electrodes having a desired shape, and a capacitor structure in which a dielectric layer is sandwiched between the capacitor electrodes on both sides is formed at a target position.

The formed capacitor is required as a basic quality to have as large an electric capacity as possible. The capacitance (C) of the capacitor is calculated from the equation C = εε ₀ (A / d) (ε ₀ is the dielectric constant of vacuum). Therefore, in order to increase the capacitor capacity, i) the surface area (A) of the capacitor electrode is increased. ii) Reduce the thickness (d) of the dielectric layer. iii) Increase the relative dielectric constant (ε) of the dielectric layer. Any one of these methods may be adopted.

  However, with regard to the surface area (A) of i), the same demands have been made on the printed wiring board due to the recent trend of miniaturization of electronic and electrical equipment, and within a certain printed wiring board area. It is almost impossible to increase the area of the capacitor electrode. With regard to reducing the thickness (d) of the dielectric layer of ii), if the dielectric layer includes a skeleton material such as a conventional glass cloth as represented by prepreg, there is a skeleton material. There is a limit to thinning. On the other hand, if the skeleton material is simply omitted using the conventional dielectric layer constituent material, the dielectric layer at the site where the copper foil layer has been etched away by the shower pressure of the etchant when the capacitor electrode is formed by etching is destroyed. There was a problem of doing. From these facts, it has become common to consider increasing the relative dielectric constant (ε) of the dielectric layer of iii).

  That is, as disclosed in Patent Document 4, a skeleton material such as a glass cloth is essential for the configuration of the dielectric layer, and the dielectric layer is made thin by making the skeleton material non-woven or the like. Capacitor capacitance has been increased by reducing the overall thickness and using a resin in which a dielectric filler is dispersed in the constituent material of the dielectric layer.

JP 2003-198091 A

Technical background regarding conventional printed wiring board shape: Furthermore, in a normal printed wiring board, a circuit formed by etching a copper foil layer protrudes from the outer layer surface, and by physically hooking this circuit, Defects such as circuit disconnection and circuit peeling occurred. For this reason, printed circuit boards on which fine circuits are formed require more care in handling, causing excessive packaging and a reduction in work efficiency. In this regard, various techniques have been disclosed as disclosed in Patent Documents 5 to 7 as the problem can be solved if the outer layer circuit is embedded in the insulating base material. .

Publication No. 2896116 JP 2000-332387 A JP 09-191178 A

  However, conventional prepregs containing skeletal materials usually use a method in which the skeleton material is impregnated with a resin component and then dried, which causes problems related to laser drilling workability and makes fine pitches. It will be difficult to fully meet the requirements. On the other hand, there is a demand for further increase in the capacitance of the built-in capacitor circuit, and the demand for stabilization of the capacitance is increasing day by day, and the requirement for stabilization of the dielectric layer thickness can be satisfied. There is no current situation.

Issues related to laser drilling workability : In order to improve the laser drilling workability and meet the demand for fine pitch, it is considered that the thickness of the skeleton material should be reduced. However, the nonwoven fabric itself is inferior in strength compared to the cloth type, and the nonwoven fabric itself is liable to cause a cutting failure due to the resin weight impregnated when the nonwoven fabric is impregnated and pulled up from the immersed resin. There was a drawback. And even if it was a cross type woven fabric, the problem similar to the nonwoven fabric had arisen, so that the thickness became thin.

  Therefore, at the same time as achieving the purpose of reducing the thickness of the insulating resin layer for weight reduction, reduce the amount of resin impregnated into the nonwoven fabric or woven fabric and supply a prepreg using a thinner nonwoven fabric or woven fabric. It has been said. However, the copper-clad laminate is produced by attaching a copper foil to a prepreg by pressing. At this time, the surface of the copper foil is subjected to roughening treatment with unevenness, and this roughening treatment penetrates into the resin of the base material to obtain the anchor effect and improve the adhesion strength. If the prepreg is reduced below a certain level, the prepreg skeleton material and the roughening treatment of the copper foil surface will come into contact with each other, and the adhesion of the resin of the base material will be deteriorated and the peeling strength will be deteriorated. Even the possibility of facilitating migration along the fibers of the skeletal material due to contact was to be considered.

  For these reasons, the skeleton material included 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 roughen the attached copper foil. There has been a desire for materials and methods that can more safely prevent contact with the skeletal material.

Problems related to a printed wiring board provided with a capacitor circuit: On the other hand, even in the dielectric layer of the capacitor circuit, the occurrence of a migration phenomenon when moisture is absorbed becomes a problem. The migration phenomenon in the dielectric layer containing the skeleton material is caused by the electrophoretic diffusion movement of the copper component of the copper plating layer of the printed wiring board and the constituent metal component of the dielectric filler along the interface between the skeleton material and the resin. This is to cause a short circuit failure between adjacent circuits. It is considered that such a phenomenon is likely to occur due to the presence of a skeleton material (particularly a cross-type material). This is because the layer used as the dielectric layer is made of a resin in which a dielectric filler is dispersed with a considerably high filling rate.

  Therefore, a method for manufacturing a printed wiring board that does not include a skeleton material, can be formed to an arbitrary film thickness, and is not destroyed by the shower pressure of the etchant during etching has been desired for the dielectric layer of the capacitor circuit. It was.

Issues related to the shape of the printed wiring board: Furthermore, to make the outer layer circuit of a normal printed wiring board embedded in an insulating substrate, the circuit is once filled with resin and further polished to create an embedded state, etc. In general, however, complicated processes are employed, and the technology cannot be widely spread in the market.

  From the problems described above, good laser processing performance that can further improve the fine pitch, and at the same time, manufacture of printed wiring boards that can maintain a good dielectric layer thickness for capacitor circuit formation applications A method has been desired. Moreover, if the outer layer circuit of the printed wiring board is embedded in the insulating resin base material, it has extremely high handling properties as a printed wiring board and can effectively prevent physical circuit damage. It is.

  Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described. These manufacturing methods will be described in the simplest form, and those skilled in the art can apply the method described below to increase the number of layers. It becomes possible to manufacture the printed wiring board. Further, the following manufacturing method is a case of a basic concept (hereinafter referred to as “manufacturing method 1”) used for manufacturing a normal printed wiring board and a printed wiring board including a capacitor circuit (hereinafter referred to as “manufacturing method 2”). Will be described separately.) This is because, in the case of a printed wiring board provided with a capacitor circuit, a case where a dielectric filler is contained in a layer constituting the dielectric layer can be considered. The printed wiring board obtained by the manufacturing method according to the present invention is characterized in that the outer circuit is embedded in the insulating resin layer.

<Manufacturing method 1>
Here, the most basic manufacturing method among the manufacturing methods of the printed wiring board according to the present invention will be described. This manufacturing method includes the steps A) and B) described below with reference to FIGS. 1 to 8. In addition, as a precaution, the drawing shows the processing flow as a schematic diagram observed from a cross section, but the thickness of each layer corresponds to the actual product so that the explanation is easy to understand. Not what you want.

Step A): The first step A) will be described with reference to FIGS. In short, this step is to form the circuit sheet S with an insulating layer by etching the copper foil layer 3 of the copper foil 2 with an insulating layer to form a circuit. The copper foil 2 with an insulating layer used in this step has a cross-sectional layer configuration as shown in FIG. 5 (8), and the surface roughness (Rz) of the bonding surface of the copper foil on one side of the copper foil. A cured resin layer 4 having a thickness 0.5 μm to 10 μm thicker than the value is provided, and a semi-cured resin layer 6 including a skeleton 5 is provided on the cured resin layer 4. Then, using this copper foil with an insulating layer, an etching resist layer R is formed on the copper foil surface as shown in FIG. 6 (9), and the circuit pattern is exposed and developed as shown in FIG. 6 (10). to form a circuit C ₁ copper foil layer 3 is etched as shown in FIG. 7 (11), by peeling off the etching resist layer R as shown in FIG. 6 (12), the circuit sheet S with an insulation layer Is formed.

  As used herein, the copper foil 2 with an insulating layer is a semi-cured resin layer including a cured resin layer 4 having a predetermined thickness on one side in contact with the copper foil surface, and including a skeleton 5 on the cured resin layer 4. 6 is provided. Here, what is 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 a converted thickness when it is considered that the cured resin layer is formed on a completely flat surface. The lower limit value (the surface roughness (Rz) value of the adhesive surface of the copper foil +0.5) μm thickness is to completely cover the unevenness of the roughened surface of the copper foil, and the copper foil It is determined in consideration of safety for functioning as a barrier of a semi-cured resin when etching is performed by applying an etching solution to the layer side. On the other hand, the upper limit value (the value of the surface roughness (Rz) of the adhesive surface of the copper foil + 10) μm or less is explained in detail in the description of the hot forming press process below, but this cured resin layer Must be of a thickness and material that can be pushed and pierced by the circuit during press molding (hereinafter referred to as "breaking"). Therefore, it is determined in consideration that the thickness of the copper foil used for a general rigid plate is 9 μm or more. Accordingly, when the thickness exceeds 10 μm, it is difficult to break the cured resin layer 4 by a circuit.

  Although the thickness of the cured resin layer 4 described above is limited, the thickness of the semi-cured resin layer 6 provided on the cured resin layer is not particularly limited. However, since the circuit becomes a layer that is substantially embedded during hot forming press processing, depending on the board design as long as it is necessary to have a thickness that can sufficiently secure interlayer insulation so as not to deteriorate the crosstalk characteristics The thickness can be adjusted arbitrarily. In the 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, manufacture of the copper foil with an insulating layer used by this invention is demonstrated using FIGS. Figure 1 (1) thermosetting resin solution on one side of the copper foil layer 3 as shown in the coating to form a coating film S _1, preferably dried as shown in FIG. 1 (2), which Figure 2 As shown in (3), it puts in the heating furnace 20 (the case where the heater 21 is dried is described in the drawing) and is cured by heat treatment to form the cured resin layer 4.

Then, 3 (4) a thermosetting resin solution on the cured resin layer 4 as shown in by coating to form a coating film S _2, is to a semi-cured state as shown in FIG. 3 (5) . Thereafter, the procedure shown in FIG. 4 (6), the skeletal material 5 is placed on the coating film S ₂ in a semi-cured state in the first step, as shown in the second step of FIG. 4 (6) semi-cured the skeletal material 5 is pressed against the coating film S ₂ state (in FIG. 4, the manner in which bonding using a heating roll 22 is shown schematically.), the final form of the FIG. 4 (6).

Furthermore, as shown in FIG. 5 (7), which was re-fluidize the resin constituting the coating film S ₂ in a semi-cured state by heating in the heating furnace 20, skeletal material is the nonwoven or woven fabric 5 The nonwoven fabric or woven fabric is covered with a constituent resin of a thermosetting resin. When the operation in the furnace is completed, it is immediately taken out of the furnace and preferably subjected to a temperature lowering process such as blast using an air blower device 23 as shown in FIG. It ensures maintenance. As described above, the copper foil 2 with an insulating layer having the insulating layer composed of the cured resin layer 4 and the semi-cured resin layer 6 including the skeleton material 5 on one surface of the copper foil is obtained.

  Here, the copper foil constituting the copper foil layer 3 is a copper foil used for an electronic material of a printed wiring board, such as a rolled copper foil obtained by rolling, an electrolytic copper foil obtained by electrolysis, and the like. Any foil can be used. This copper foil is described as a concept including a copper foil with a carrier foil. The copper foil with carrier foil has a carrier foil attached to the opposite side of the copper foil to the base, and the carrier foil is pressed to form a copper-clad laminate, and then the carrier foil is removed. And used as a normal copper-clad laminate. The advantage of using copper foil with carrier foil is that it is easy to handle thin copper foil with a thickness of 9μm, etc., and prevents foreign matter adhesion and contamination on the copper foil surface that may occur during press processing. The surface can be protected from damage such as scratches.

  As the resin constituting the cured resin layer 4, an epoxy resin is generally used. This is because it is widely used in printed wiring board applications. Accordingly, the resin constituting the cured resin layer 4 is not particularly limited as long as it is a resin having thermosetting properties and can be used for a printed wiring board in the field of electric and electronic materials. There is no. The cured resin layer 4 generally employs a method of applying a liquid thermosetting resin solution to a copper foil surface using a solvent, but a semi-cured resin film is laminated. It is also possible to adopt a method of pasting. When making a thermosetting resin solution using a solvent, for example, an epoxy resin, a curing agent, and a curing accelerator are blended, and the viscosity is adjusted using a solvent such as methyl ethyl ketone. As long as the thickness of the cured resin layer 4 falls within a 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 are also particularly limited. Is not necessary.

  Furthermore, the thermosetting resin having the same concept as the above-described cured resin layer 4 and the skeleton material 5 described below are also used for the resin constituting the semi-cured resin layer 6. However, the resin composition constituting the resin constituting the semi-cured resin layer 6 and the cured resin layer 4 is not necessarily the same. Here, the manufacturing method of the semi-cured resin layer 6 shown in FIGS. First, a thermosetting resin solution is applied on the cured resin layer 4 formed on the copper foil surface to remove the organic solvent component. Then, a skeleton material 5 such as a nonwoven fabric or a woven fabric described below is placed, and the thermosetting resin solution is infiltrated into the skeleton material 5 so that the resin is oozed out to the opposite surface of the skeleton material. Then, drying is performed without curing, and the semi-cured resin layer 6 including the skeleton material 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. The thickness of the semi-cured resin layer to be formed (X (μm)) is preferably set to a thickness of X-40 (μm) to X-3 (μm). For example, in order to set the thickness of the semi-cured resin layer to 100 μm, a liquid resin is applied to the surface of the copper foil with a coating thickness of 100−40 = 60 μm to 100−3 = 97 μm. I will leave it. By doing so, it is possible to form the semi-cured resin layer 6 having a desired thickness on the surface of the cured resin layer 4. When the coating film thickness is less than X-40 (μm), sufficient adhesion between the finally obtained semi-cured resin layer and the substrate to be bonded cannot be obtained, and the coating film thickness is set to X-3 ( Even if the thickness exceeds (μm), the effect of improving the adhesion between the semi-cured resin layer and the base material to be bonded is not increased.

Then, on the coating film S ₂ of the thermosetting resin solution, by placing the scaffold material 5 (nonwoven or woven fabric), glass fiber resin component of the coating film S ₂ constituting the skeleton member 5 or By infiltrating using the capillary phenomenon of the organic fiber and oozing to the opposite side of the skeleton material 5, the surface of the skeleton material 5 is completely covered to obtain the copper foil 2 with an insulating layer. It is preferable to use organic fibers that do not decompose or melt at the solder bath temperature (about 260 ° C.), and use any one of aramid, wholly aromatic polyester, and PBO (polyparaphenylene benzobisoxazole). Is preferred.

  At this time, in the steps shown in FIG. 3 to FIG. 5, it is preferable to impregnate the nonwoven fabric or woven fabric 5 with a resin by coating the nonwoven fabric or woven fabric 5 in consideration of the following points. The coating film of the thermosetting resin solution contains a large amount of an organic solvent. Therefore, when the skeleton material 5 is placed on the surface without removing the solvent at all and the following steps are performed, the nonwoven fabric or woven material of the skeleton material 5 is finally dried when it is dried to a semi-cured state. Bubbles are easily generated in the form of being trapped in the fabric fibers. Therefore, as shown in FIG. 3 (5), it is preferable to remove a certain amount of solvent before the skeleton material 5 is placed on the surface of the coating film in order to prevent generation of bubbles. The removal of the solvent may be performed simply by air drying or by heating to a temperature range below the curing temperature.

  Before placing the skeletal material 5, when the resin component of the coating film is in a semi-cured state and the skeletal material is placed on the semi-cured coating film, between the coating film and the skeletal material, As shown in FIG. 4 (6), it is preferable to temporarily press the skeleton material to the coating film so that no gap is formed. Then, the coating resin semi-cured as shown in FIG. 5 (7) is heated below the curing temperature to reflow, and the capillary phenomenon of the glass fiber or aramid fiber constituting the skeleton material 5 is used. And let it penetrate.

  Here, it is desirable to use a nonwoven fabric or a woven fabric using glass fiber or aramid fiber as the skeleton material 5. This is because all of them have a long track record of use in printed wiring board applications and are highly reliable materials. However, the material of the non-woven fabric or the woven fabric is not particularly limited, and can be used for printed wiring board applications as long as it has sufficient mechanical characteristics. In addition, in order to improve the wettability with the resin of the surface, it is preferable to give the fiber which comprises the nonwoven fabric and woven fabric used here to a silane coupling agent process. The silane coupling agent at this time may be an amino or epoxy silane coupling agent depending on the purpose of use.

  And although there is no particular limitation on the thickness of the skeleton 5, if the method for producing a copper foil with an insulating layer as in the present invention is adopted, the thickness of 50 μm or less that could not be conventionally used is used. A thin nonwoven fabric or woven fabric can be used. Conventionally, a skeleton material is immersed in a resin varnish, impregnated, pulled into a drying tower and dried to a semi-cured state, and a method of forming a prepreg is adopted. A thin nonwoven fabric having a thickness of 50 μm or less or a thickness of 20 μm or less is employed. Due to the weak mechanical strength of the woven fabric, a defect that breaks and breaks immediately occurred. However, if the method for producing a copper foil with an insulating layer according to the present invention is employed, even if a thin non-woven fabric having a thickness of 50 μm or less or a woven fabric having a thickness of 20 μm or less is used, it will not break or break. Since such a thin skeleton material can be used, the printed wiring board obtained by the manufacturing method according to the present invention exhibits extremely good laser drilling performance, and at the same time the minimum required for the printed wiring board. The strength can be ensured and the demand for fine pitch circuit formation in the market can be met.

  As described above, the copper foil with an insulating layer used in the production method according to the present invention is obtained. Then, as shown in FIG. 6 (9), an etching resist layer R is provided on the surface of the copper foil layer 3 of the copper foil 2 with insulating layer, and the circuit pattern is exposed and developed as shown in FIG. 6 (10). To do. Then, copper etching is performed from the surface on the copper foil layer side as shown in FIG. 7 (11), and the etching resist is peeled off as shown in FIG. 7 (12) to form a circuit pattern. This is the circuit sheet 7 with an insulating layer. At the time of this circuit etching, if the etching solution is applied 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 an etching solution, a resist remover, or the like wraps around the semi-cured resin layer 6 side, it is preferable to use a protective film such as a PET film or a polyethylene film on the surface of the semi-cured resin layer 6.

Step B): Then, as shown in FIG. 8 (13), the semi-cured resin layer 6 of the circuit sheet 7 with an insulating layer obtained as described above is bonded to a base material (inner circuit C _{2 in the} drawing). The inner layer core material 24 is used. At the time of hot press molding, heating at about 170 ° C. to 180 ° C. is performed and pressure is applied. By this pressurization, the circuit is pushed into the semi-cured resin layer side while causing cracks in the cured resin layer underneath. In the present invention, this phenomenon is referred to as defeat. At the time of rupture, a crack is generated in the cured resin layer 4 and the thermosetting resin of the semi-cured resin layer 6 starting to reflow from the crack oozes out along the side wall surface of the circuit, so that the circuit is completely formed. An insulating layer embedded in the insulating resin layer and integrated with the cured resin layer 4 and the semi-cured resin layer 6 is formed. As described above, the hot pressing process is completed, it's a printed wiring board 1a having a circuit C ₁ which is embedded disposed in the insulating resin layer according to the present invention shown in FIG. 8 (14) is obtained.

<Method for producing printed wiring board for capacitor>
Since the following steps are common to the printed wiring board manufacturing method described above, the description of the common parts is omitted to avoid redundant explanation, and the printed circuit for capacitors is referred to with reference to FIGS. Only the characteristic parts in the method of manufacturing the wiring board 1b will be described in the order of steps.

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

Step B): In this step, the semi-cured resin layer of the capacitor circuit sheet with an insulating layer is brought into contact with and overlapped with the base material surface to be laminated, and the copper foil of the circuit portion is cured by hot press molding. The printed wiring board is provided with a capacitor circuit that breaks the resin layer, is embedded in the semi-cured resin layer, and is embedded in the insulating resin layer. Therefore, the hot forming press is used to obtain a printed wiring board in which a circuit including one of the electrode shapes serving as the upper electrode or the lower electrode of the capacitor circuit is embedded. Since there is no difference, and those skilled in the art can easily understand, detailed description of this process is also omitted.

Step C): In this step, as shown in FIG. 9A, the surface of the dielectric layer 11 of the copper foil 10 with dielectric layer is brought into contact with the surface of the circuit C ₁ embedded in the printed wiring board 1a having the capacitor circuit. Overlapping. And it is set as the copper clad laminated board 12 in which a copper foil layer is located in an outer layer as shown in FIG.9 (2) by carrying out hot press molding. This copper foil 10 with a dielectric layer is provided with a resin layer or a resin layer containing a dielectric filler constituting the dielectric layer 11 when a capacitor circuit is formed on one surface of the copper foil. Therefore, the layer structure seen from the cross section has an extremely simple structure as can be seen from FIG. In FIG. 9 to FIG. 11, description is not made until a state in which the dielectric layer includes a dielectric filler can be seen. The performance of the capacitor depends on the type of resin and dielectric filler constituting the dielectric layer and the thickness of the dielectric layer.

In the case of the present invention, since the surface of the printed wiring board provided with the capacitor circuit manufactured in the step B) is flat and the circuit C ₁ part does not protrude, it is not necessary to consider the spread of the resin component to the gap between the 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. Moreover, since the surface of the printed wiring board is flat, it is easy to ensure the thickness accuracy of the dielectric layer, the dielectric layer can be easily thinned, and a capacitor circuit having a large capacitance can be formed. is there.

  Here, the resin composition which comprises the dielectric layer 11 of the copper foil 10 with a dielectric layer is demonstrated. Originally, the resin composition is not particularly limited, and a material to be used may be appropriately selected in consideration of design quality such as electric capacity required for the capacitor circuit. However, since the surfaces of the printed wiring boards to be bonded are flat and have no unevenness, it is preferable to employ a resin composition having excellent adhesion from the viewpoint of preventing interfacial peeling (delamination) as much as possible. Particularly desirable is a resin composition as described below.

  If the resin composition desirable for constituting the dielectric layer is simply expressed, it consists 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. is there.

  The “epoxy resin” referred to here has two or more epoxy groups in the molecule, and can be used without any particular problem as long as it can be used for electric / electronic materials. Among them, from the group of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, novolac type epoxy resin, cresol novolac type epoxy resin, alicyclic epoxy resin, brominated epoxy resin, glycidylamine type epoxy resin It is preferable to use one kind or a mixture of two or more selected.

  This epoxy resin is the main component of the resin composition and is used in a blending ratio of 20 to 80 parts by weight. However, it is assumed here that the curing agent described below is included. Therefore, when the epoxy resin in the state containing the curing agent is less than 20 parts by weight, the thermosetting property is not sufficiently exhibited and the function as a binder with the base resin and the adhesiveness with the copper foil are sufficiently obtained. If the amount exceeds 80 parts by weight, the viscosity of the resin solution becomes too high, making it difficult to apply a uniform thickness to the copper foil surface, and the amount of aromatic polyamide resin polymer added later Cannot be balanced, and sufficient toughness after curing cannot be obtained.

  The epoxy resin “curing agent” includes dicyandiamide, imidazoles, amines such as aromatic amines, phenols such as bisphenol A and brominated bisphenol A, novolacs such as phenol novolac resin and cresol novolac resin, anhydrous Acid anhydrides such as phthalic acid. Since the addition amount of the curing agent with respect to the epoxy resin is naturally derived from the respective equivalents, it is considered that there is no need to specify the mixing ratio strictly strictly. 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 and a rubber resin. Here, the aromatic polyamide resin is synthesized by condensation polymerization of an aromatic diamine and a dicarboxylic acid. In this case, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylsulfone, m-xylenediamine, 3,3'-oxydianiline, or the like is used as the aromatic diamine. As the dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid or the like is used.

  The rubber resin to be reacted with the aromatic polyamide resin is described as a concept including natural rubber and synthetic rubber. The latter synthetic rubber includes styrene-butadiene rubber, butadiene rubber, butyl rubber, and ethylene-propylene rubber. Etc. Furthermore, when ensuring the heat resistance of the dielectric layer to be formed, it is also useful to select and use a synthetic rubber having heat resistance such as nitrile rubber, chloroprene rubber, silicon rubber, urethane rubber or the like. Since these rubber resins react with an aromatic polyamide resin to produce a copolymer, it is desirable to have various functional groups at both ends. In particular, it is useful to use CTBN (carboxy group-terminated butadiene nitrile).

  The aromatic polyamide resin and the rubbery resin that constitute the aromatic polyamide resin polymer are preferably used in a blend of 25 to 75 parts by weight of the aromatic polyamide resin and the remaining rubbery resin. When the amount of the aromatic polyamide resin is less than 25 parts by weight, the abundance ratio of the rubber component becomes too high and the heat resistance is inferior. On the other hand, when it exceeds 75 parts by weight, the abundance ratio of the aromatic polyamide resin becomes too large. The hardness after curing becomes too high and becomes brittle. This aromatic polyamide resin polymer is used for the purpose of avoiding damage such as under-etching by the etching solution when etching the copper foil after being processed into a copper-clad laminate.

  The aromatic polyamide resin polymer is required to have a property of being soluble in a solvent. This aromatic polyamide resin polymer is used in a blending ratio of 20 to 80 parts by weight. When the amount of the aromatic polyamide resin polymer is less than 20 parts by weight, it becomes too brittle under general press conditions for producing a copper clad laminate, and becomes microcracked easily on the substrate surface. On the other hand, there is no particular problem even if the aromatic polyamide resin polymer is added in an amount exceeding 80 parts by weight, but the strength after curing is not further improved even if the aromatic polyamide resin polymer is added in an amount exceeding 80 parts by weight. It is. Therefore, if economics are considered, it can be said that 80 weight part is an upper limit.

  “A curing accelerator to be added in an appropriate amount as needed” includes tertiary amines, imidazoles, urea-based curing accelerators, and the like. In the present invention, the mixing ratio of the curing accelerator is not particularly limited. This is because the curing accelerator may be arbitrarily selected by the manufacturer in consideration of production conditions in the process of producing the copper-clad laminate.

Next, the dielectric filler used for forming the dielectric layer 11 will be described. This dielectric filler is mixed with the resin component used to constitute the above-described dielectric layer and dispersed in the dielectric layer and is finally present in the capacitor when processed into a capacitor shape. It is used to increase the electric capacity. The dielectric filler has a perovskite structure such as BaTiO ₃ , SrTiO ₃ , Pb (Zr—Ti) O ₃ (common name PZT), PbLaTiO ₃ · PbLaZrO (common name PLZT), SrBi ₂ Ta ₂ O ₉ (common name SBT), and the like. It is preferable to use a complex oxide dielectric powder.

And as for the powder characteristic of this dielectric filler, it is preferable that a particle diameter is a thing of the range of 0.1-1.0 micrometer first. The particle size referred to here is indirect in which the average particle size is estimated from the measured values of the laser diffraction scattering type particle size distribution measurement method and the BET method because the particles form a certain secondary aggregation state. The measurement is inferior in accuracy and cannot be used. The average particle size is obtained by directly observing the dielectric filler with a scanning electron microscope (SEM) and analyzing the SEM image. In this specification, the particle size at this time is indicated as _DIA . In addition, the image analysis of the powder of the dielectric filler observed using a scanning electron microscope (SEM) in this specification is performed using IP-1000PC manufactured by Asahi Engineering Co., Ltd. Circular particle analysis was performed with an overlap degree of 20, and the average particle diameter _DIA was obtained.

Further, the weight cumulative particle diameter D ₅₀ by the laser diffraction scattering particle size distribution measurement method is 0.2 to 2.0 μm, and the weight cumulative particle diameter D ₅₀ and the average particle diameter D _IA obtained by image analysis are used. Therefore, it is required that the dielectric powder has a perovskite structure having a substantially spherical shape with a cohesion value represented by D ₅₀ / D _IA of 4.5 or less.

The weight cumulative particle size D ₅₀ by the laser diffraction scattering type particle size distribution measurement method is a particle size at 50% weight accumulation obtained by using the laser diffraction scattering type particle size distribution measurement method, and this weight cumulative particle size D _50. The smaller the value of, the greater the proportion of fine powder particles in the particle size distribution of the dielectric filler powder. In the present invention, this value is required to be 0.2 μm to 2.0 μm. That is, when the value of the weight cumulative particle diameter D ₅₀ is less than 0.2 μm, the progress of aggregation is remarkably satisfied with the degree of aggregation described below, regardless of the production method of the dielectric filler powder. It must not be. On the other hand, when the value of weight-cumulative particle diameter D ₅₀ is more than 2.0μm, since the use of a dielectric filler embedded capacitor layer forming a printed wiring board is where an object of the present invention is not is there. That is, the dielectric layer of the double-sided copper clad laminate used to form the capacitor layer is usually 10 μm to 50 μm thick, and 2.0 μm is required to uniformly disperse the dielectric filler. It is an upper limit.

The weight cumulative particle size D ₅₀ in the present invention is measured by mixing and dispersing the dielectric filler powder in methyl ethyl ketone, and using this solution as a laser diffraction scattering type particle size distribution measuring device Micro Trac HRA 9320-X100 (manufactured by Nikkiso Co., Ltd.). The measurement was performed by putting it in the circulatory system.

Here, the concept of cohesion is used, which is adopted for the following reason. That is, the value of the weight cumulative particle diameter D ₅₀ obtained by using the laser diffraction / scattering particle size distribution measurement method is not considered to be a direct observation of each individual particle diameter. This is because the powder particles constituting most of the dielectric powder are not so-called monodispersed powders in which individual particles are completely separated, but are in a state where a plurality of powder particles are aggregated and aggregated. This is because the laser diffraction / scattering particle size distribution measurement method regards the aggregated particles as one particle (aggregated particles) and calculates the weight cumulative particle size.

On the other hand, since the average particle diameter _DIA obtained by image processing the observation image of the dielectric powder observed using the scanning electron microscope is obtained directly from the SEM observation image, the primary particles are On the other hand, the presence of the agglomerated state of the particles is not reflected at all.

Given Thus, the present inventors have found that, by using the average particle diameter D _IA obtained by a weight cumulative particle diameter D ₅₀ and the image analysis of a laser diffraction scattering particle size distribution measurement method, at D _{50 /} D _IA The calculated value was taken as the degree of aggregation. That is, on the assumption that the value of D ₅₀ and D _IA in copper powder of the same lot can be measured with the same accuracy, considering theory described above, the value of D ₅₀ to be reflected in the measured values that the aggregation state Is considered to be larger than the value of _DIA (similar results can be obtained even in actual measurement).

At this time, the value of D _50, if the granular state of aggregation of the dielectric filler powder is completely eliminated, Yuki approaching the value of the infinitely D _IA, the value of a degree of aggregation D _{50 /} D _IA is It approaches 1 It can be said that it is a monodispersed powder in which the agglomeration state of the powder is completely lost when the aggregation degree becomes 1. However, in reality, the degree of aggregation may be less than 1. Theoretically, in the case of a true sphere, it does not become a value less than 1, but in reality, it seems that a cohesion value of less than 1 is obtained because the powder is not a true sphere. is there.

  In this invention, it is calculated | required that the aggregation degree of this dielectric filler powder is 4.5 or less. If the degree of aggregation exceeds 4.5, the level of aggregation of the dielectric filler powder particles becomes too high, and uniform mixing with the binder resin described above becomes difficult.

  Regardless of the alkoxide method, hydrothermal synthesis method, oxalate method, etc. used as the method for producing the dielectric filler powder, a certain aggregation state is inevitably formed, so the above-mentioned aggregation degree is satisfied. Dielectric filler powder that cannot be generated can be generated. In particular, in the case of the hydrothermal synthesis method which is a wet method, the formation of an aggregated state tends to occur. Therefore, the aggregated state of the dielectric filler powder can be set within the above-described aggregation degree range by performing a pulverization process for separating the agglomerated powder into one granular particle. is there.

  If the purpose is simply pulverization, high energy ball mill, high-speed conductor impingement airflow pulverizer, impact pulverizer, gauge mill, medium agitation mill, high water pressure Various things such as a pulverizer can be used. However, in order to ensure the mixability and dispersibility of the dielectric filler powder and the binder resin, the viscosity reduction as a dielectric filler-containing resin solution described below should be considered. In order to reduce the viscosity of the dielectric filler-containing resin solution, the specific surface area of the dielectric filler powder is required to be small and smooth. Therefore, even if granulation is possible, it should not be a granulation technique that damages the surface of the granule during granulation and increases its specific surface area.

  Based on this recognition, the inventors of the present invention diligently researched and found that the two methods are effective. What is common to these two methods is that the powder particles of the dielectric filler are kept from contacting the inner wall, stirring blades, grinding media, etc. This is a method in which pulverization is sufficiently possible by causing mutual collisions. That is, contact with parts such as the inner wall of the apparatus, stirring blades, and grinding media damages the surface of the powder, increases the surface roughness, and deteriorates the sphericity, thereby preventing this. . Then, by causing sufficient collision between the powder particles, it is possible to disaggregate the powder particles in an agglomerated state, and at the same time, it is possible to employ a method capable of smoothing the surface of the powder particles by collision between the powder particles.

  One of them is to pulverize the dielectric filler powder in an agglomerated state using a jet mill. "Jet mill" here refers to the use of a high-speed air stream, putting dielectric filler powder in this air stream, causing the particles to collide with each other in this high-speed air stream, and performing the pulverization operation. .

  In addition, a slurry in which the dielectric filler powder in an agglomerated state is dispersed in a solvent that does not destroy the stoichiometry is pulverized using a fluid mill using centrifugal force. By using the “fluid mill using centrifugal force”, the slurry is allowed to flow at a high speed so as to draw a circumferential trajectory. And then pulverize. By doing in this way, the dielectric filler powder which finished the granulation work is obtained by washing, filtering, and drying the slurry after the granulation work. By the method described above, the degree of aggregation can be adjusted and the powder surface of the dielectric filler powder can be smoothed.

  The above-described thermosetting resin and dielectric filler are mixed to form a dielectric filler-containing resin for forming a capacitor layer of a printed wiring board. At this time, the blending ratio of the thermosetting resin and the dielectric filler is desirably 75 wt% to 85 wt% in the content of the dielectric filler and the remaining thermosetting resin. If the dielectric filler content is less than 75 wt%, the dielectric constant of 20 currently required in the market cannot be satisfied. If the dielectric filler content exceeds 85 wt%, the thermosetting resin content Since the rate becomes less than 15 wt%, the adhesion between the dielectric filler-containing resin and the copper foil laminated thereon is impaired, and it becomes difficult to produce a copper-clad laminate that satisfies the required characteristics for producing a printed wiring board. is there.

  If the dielectric layer of the capacitor layer of a printed wiring board is configured using the dielectric filler-containing resin described above, the dielectric layer can be thinned with sufficient film thickness uniformity. Yes, resulting in a capacitor circuit with very good high capacitance.

Step D): In this step, the outer layer copper foil 3 to form an etching resist layer, exposing the capacitor circuit pattern and developed to the copper foil surface is etched to form a capacitor circuit C _3, peeling off the resist layer it is, to form a capacitor circuit C ₃ of the other side of the electrode is to the printed wiring board with a capacitor circuit. This process is shown in FIG. 10 and FIG.

  That is, the circuit including the other electrode shape that becomes the upper electrode or the lower electrode of the capacitor circuit formed in the above-described step A) is processed in the same manner as etching the outer layer copper foil of the multilayer printed wiring board. . Therefore, those skilled in the art can easily understand this, and since there are many overlapping parts with the description of step A), detailed description of this step is omitted.

  In the description of the manufacturing method described above, the image of laminating on both sides in the drawings has been shown. However, those skilled in the art will be able to print according to any layer configuration including single-sided, double-sided, multi-layer boards of 3 layers or more. This manufacturing method can also be applied to a wiring board.

  The printed wiring board manufacturing method described above is a method that can very efficiently manufacture a printed wiring board having a circuit embedded in an insulating resin layer, and the surface of the obtained printed wiring board is very flat. In addition, since the skeletal material in the insulating layer can be made extremely thin, it has excellent laser drilling workability and dramatically improves the processing efficiency with a low-power carbon dioxide laser. It becomes possible to meet the demand for mounting.

  In addition, since the dielectric layer is bonded to the surface of the flat printed wiring board by adopting the manufacturing method of the printed wiring board including the capacitor circuit embedded and arranged in the insulating resin layer according to the present invention, the capacitor circuit Even if the dielectric layer thickness is designed to be thin, extremely high thickness accuracy can be obtained.

  Hereinafter, the best embodiment of the method for manufacturing a printed wiring board according to the present invention will be described.

  In this embodiment, according to the flow shown in FIGS. 1 to 5, an electrolytic copper foil 3 having a nominal thickness of 12 μm and a roughened surface having a surface roughness (Rz) of 3.0 μm is used. Copper foil 2 was produced.

  First, the epoxy resin composition used for forming the cured resin layer 4 and the semi-cured resin layer 6 was prepared. Here, as resin, bisphenol A type epoxy resin (trade name: YD-128, manufactured by Tohto Kasei Co., Ltd.) 30 parts by weight, o-cresol type epoxy resin (trade name: ESCN-195XL80, manufactured by Sumitomo Chemical Co., Ltd.) 50 parts by weight 16 parts by weight of dicyandiamide (4 parts by weight as dicyandiamide) in the form of a dimethylformaldehyde solution having a solid content of 25% as an epoxy resin curing agent, and 2-ethyl 4-methylimidazole (trade name: KAZOLE 2E4MZ, Shikoku Chemicals) as a curing accelerator 0.1 part by weight was dissolved in a mixed solvent of methyl ethyl ketone and dimethyl formaldehyde (mixing ratio: methyl ethyl ketone / dimethyl formaldehyde = 4/6) to obtain an epoxy resin composition having a solid content of 60%. .

Production of copper foil with insulating layer: According to the flow shown in FIGS. 1 and 2, this epoxy resin composition is uniformly applied to the roughened surface (Rz = 2.0 μm) of electrolytic copper foil 3 having a nominal thickness of 12 μm. Apply, leave at room temperature for 30 minutes, blow with warm air at 150 ° C for 2 minutes using a hot air dryer to remove a certain amount of solvent, and further cure at 170 ° C for 60 minutes Processing was performed to form a cured resin layer 4. The amount of the epoxy resin composition applied at this time was 8 μm thicker than the value of the surface roughness (Rz) of the adhesive surface of the copper foil as the film thickness after curing.

Next, the semi-cured resin layer 6 was formed on the surface of the cured resin layer 4 according to the flow shown in FIGS. The epoxy resin composition is uniformly applied to the surface of the cured resin layer 4, left at room temperature for 30 minutes, and heated at 150 ° C. for 2 minutes using a hot air dryer to give a thickness of 10 μm. The film thickness was semi-cured. And the nonwoven fabric of the aramid fiber of nominal thickness of 50 micrometers was bonded together as the frame | skeleton material 5 on this. In this lamination, the non-woven fabric is superimposed on the surface of the semi-cured coating film S ₂ and heated to 150 ° C. so that a laminating pressure of 9 kg / cm ² can be applied. Per minute. As a result, the total thickness of the coating film S2 and the skeleton 5 in the bonded state was 55 μm on average.

If the way the bonding of skeletal material 5 is completed or, by maintaining for 1 minute in an atmosphere of 0.99 ° C. using a hot-air dryer, then re-fluidize the resin in a semi-cured state of the coating film S _2, the The constituent resin component is infiltrated using the capillary phenomenon of the aramid fiber constituting the skeleton material 5 and further oozed to the side opposite to the contact surface of the skeleton material 5 with the coating film S _{2, so} that the surface of the skeleton material 5 Was completely coated and dried to form a semi-cured resin layer 6 and forcibly cooled with an air blower 23 to obtain a copper foil 2 with an insulating layer shown in FIG. The total thickness after drying of the semi-cured resin layer 6 at this time was 42 μm, and a PET film (omitted in the drawing) was laminated and pasted onto the semi-cured resin layer 6.

Production of circuit sheet with insulating layer: According to the flow shown in FIGS. 6 to 7, a dry film is laminated on the surface of the copper foil layer 3 of the copper foil 2 with the insulating layer to form an etching resist layer R, and By exposing the film for exposure on the surface of the etching resist layer R and developing it, the dry film was left only on the surface of the copper foil serving as a circuit. Thereafter, an iron chloride copper etchant is applied only to the copper foil surface, circuit etching is performed, resist stripping and PET film stripping of the semi-cured resin layer 6 are performed, and the circuit C ₁ is formed on the insulating layer as shown in FIG. Thus, a circuit sheet 7 with an insulating layer was obtained.

Hot press molding: And, according to the flow shown in FIG. 8, the inner layer core material 24 (plate thickness 0.6 mm, copper foil thickness 35 μm) having the circuit layer 7 with an insulating layer and the inner layer circuit C 2 formed on the surface -4 material), a multilayer printed wiring board 1a having four layers was manufactured. That is, as shown in FIG. 8 (13), centering on the inner layer core material 24, one circuit sheet 7 with an insulating layer is provided on each of both outer layer surfaces, and the insulating layer is the outer layer surface of the inner layer core material 24. The multilayer printed wiring board 1a having a flat surface with the outer layer circuit embedded in the insulating resin layer was manufactured by laminating and pressing so as to be in contact with each other. The press working conditions at this time were a press temperature of 180 ° C., a press pressure of 20 kg / cm ² , and a curing time of 90 minutes.

  In this example, according to the flow shown in FIGS. 9 to 11, a capacitor circuit layer is formed by laminating a copper foil 10 with a dielectric layer described below on the outer layer of the four-layer multilayer printed wiring board 1a manufactured in Example 1. 6-layer multilayer printed wiring board 1b comprising Therefore, the description which overlaps is abbreviate | omitted and will be demonstrated from manufacture of the copper foil 10 with a dielectric layer.

Production of copper foil with dielectric layer: First, a resin solution constituting the dielectric layer 11 was produced. In producing this resin solution, it is commercially available as a mixed varnish with o-cresol novolac type epoxy resin (YDCN-704 manufactured by Toto Kasei Co., Ltd.), aromatic polyamide resin polymer soluble in solvent, and cyclopentanone as solvent. BP3225-50P manufactured by Nippon Kayaku Co., Ltd. was used as a raw material. And to this mixed varnish, VH-4170 manufactured by Dainippon Ink Co., Ltd. and 2E4MZ manufactured by Shikoku Kasei Co., Ltd. as a curing accelerator were added to a phenol resin as a curing agent to obtain a resin mixture having the following blending ratio.

Resin mixture o-cresol novolac type epoxy resin 38 parts by weight Aromatic polyamide resin polymer 50 parts by weight Phenolic resin 18 parts by weight Curing accelerator 0.1 part by weight

  This resin mixture was further adjusted to a resin solid content of 30% by weight using methyl ethyl ketone to obtain a resin solution. Then, barium titanate powder, which is a dielectric filler F having the following powder characteristics, was mixed and dispersed in this resin solution to obtain a dielectric filler-containing resin solution having the following composition.

Powder characteristics of dielectric filler
Average particle diameter ( _DIA ) 0.25 μm
Weight cumulative particle size (D ₅₀ ) 0.5 μm
Aggregation degree (D ₅₀ / D _IA ) 2.0

Dielectric filler-containing resin solution
83.3 parts by weight of binder resin solution
100 parts by weight of barium titanate powder

  The dielectric filler-containing resin solution manufactured as described above is applied to the roughened surface of the electrolytic copper foil 2 having a thickness of 35 μm by using an edge coater, and air-dried for 5 minutes. Thereafter, a drying process for 3 minutes was performed in a heated atmosphere at 140 ° C. to form a semi-cured 20 μm thick dielectric layer 11.

Manufacture of printed wiring board provided with capacitor circuit: When the formation of the dielectric layer 11 is completed, as shown in FIG. 9 (1), the dielectric layer 11 is formed on the outer layer surface of the multilayer printed wiring board 1a obtained in Example 1. And 6 layers of copper-clad laminate 12 by hot pressing under heating conditions of 180 ° C. × 60 minutes.

The copper foil layers 3 on both sides of the copper clad laminate 12 produced as described above were leveled, and as shown in FIG. 10 (3), a dry film was laminated on both sides to form an etching resist layer R. . Then, as shown in FIG. 10 (3), the capacitor circuit was exposed and developed on the etching resist layer R on both surfaces thereof to form an etching pattern. Thereafter, as shown in FIG. 11, circuit etching is performed with an iron chloride etchant, etching resist is stripped, and the circuit C ₁ and the circuit C ₃ become upper or lower electrodes, and a capacitor circuit having a dielectric layer therebetween is provided. A 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 a very high value of ε = 20 was obtained, and a capacitor having a high capacitance was obtained.

Comparative Example 1

  In this comparative example, the same resin as that used in Example 1 was uniformly applied to the roughened surface of the electrolytic copper foil having a nominal thickness of 12 μm, and allowed to stand at room temperature for 30 minutes, using a hot air dryer. A constant amount of solvent was removed by blowing warm air at 150 ° C. for 5 minutes, and the resin layer was dried to a semi-cured state, thereby obtaining a conventional copper foil with resin containing no skeleton material. The coating amount of the epoxy resin composition at this time was set to 75 μm as the resin layer thickness after drying.

  And using this resin-attached copper foil instead of the copper foil 1 with an insulating layer of Example 1 mentioned above, the circuit sheet with a resin layer was obtained by the same method as Example 1, and an inner-layer core material and heat A four-layer printed wiring board was manufactured by hot pressing. As a result, at the time of circuit formation etching before hot press processing, the semi-cured resin layer may be broken by handling, even if it is lined with a PET film, there is a problem due to the absence of a skeleton material, I couldn't get a high quality product.

  The method for manufacturing a printed wiring board according to the present invention can very efficiently manufacture a printed wiring board including a circuit embedded in an insulating resin layer. Therefore, a printed wiring board having a very flat surface can be manufactured with a high yield, and the printed wiring board can be supplied to the market at a low cost. Moreover, since the printed wiring board can make the skeleton material in the insulating layer extremely thin, it has excellent laser drilling workability and also has the strength required for the substrate.

  In addition, by adopting a method for manufacturing a printed wiring board having a capacitor circuit embedded in an insulating resin layer according to the present invention, extremely high thickness accuracy can be obtained even when the dielectric layer thickness of the capacitor circuit is designed to be thin. Therefore, the quality of the printed wiring board provided with the capacitor circuit can be remarkably improved.

The schematic diagram showing the manufacture flow of copper foil with an insulating layer. The schematic diagram showing the manufacture flow of copper foil with an insulating layer. The schematic diagram showing the manufacture flow of copper foil with an insulating layer. The schematic diagram showing the manufacture flow of copper foil with an insulating layer. The schematic diagram showing the manufacture flow of copper foil with an insulating layer. The schematic diagram showing the manufacture flow from the copper foil with an insulating layer to the circuit sheet with an insulating layer. The schematic diagram showing the manufacture flow from the copper foil with an insulating layer to the circuit sheet with an insulating layer. The schematic diagram showing the press image using the circuit sheet with an insulating layer, and an inner-layer core material. The schematic diagram showing the lamination | stacking image of copper foil with a dielectric layer. The schematic diagram showing the formation flow of a capacitor circuit. The schematic diagram showing the formation flow of a capacitor circuit.

Explanation of 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 Cured resin layer 5 Skeletal material (nonwoven fabric or woven fabric)
6 Semi-cured resin layer 7 Circuit sheet with insulating layer 10 (Multilayer) Printed wiring board 11 Dielectric layer 12 Copper-clad laminate 20 Heating furnace 21 Heater 22 Crimp roll S ₁ , S ₂ Coating film C ₁ , C ₂ , C ₃ circuit R etching resist layer

Claims (5)

A method for manufacturing a printed wiring board comprising a circuit embedded in an insulating resin layer, comprising the following steps A) and B).
A) A cured resin layer that is 0.5 μm to 10 μm thicker than the surface roughness (Rz) of the adhesive surface of the copper foil is provided on one side of the copper foil, and a skeleton material is included on the cured resin layer. Using a copper foil with an insulating layer provided with a semi-cured resin layer, an etching resist layer is formed on the copper foil surface, a circuit pattern is exposed and developed, a circuit is formed by etching the copper foil surface, and a resist layer Is peeled to form a circuit sheet with an insulating layer.
B) The semi-cured resin layer of the circuit sheet with an insulating layer is brought into contact with the base material surface to be laminated, and hot-pressed so that the copper foil of the circuit portion breaks the cured resin layer, A printed wiring board including a circuit embedded in a semi-cured resin layer and embedded in an insulating resin layer. A method of manufacturing a printed wiring board comprising a capacitor circuit embedded and arranged in an insulating resin layer, comprising the following steps A) to D).
A) A cured resin layer that is 0.5 μm to 10 μm thicker than the surface roughness (Rz) of the adhesive surface of the copper foil is provided on one side of the copper foil, and a skeleton material is included on the cured resin layer. Using a copper foil with an insulating layer provided with a semi-cured resin layer, an etching resist layer is formed on the copper foil surface, the capacitor circuit pattern is exposed and developed, and the copper foil surface is etched to form an electrode on one side The capacitor circuit to be formed is formed, and the resist layer is peeled to form a capacitor circuit sheet with an insulating layer.
B) Contacting and superposing the semi-cured resin layer of the capacitor circuit sheet with insulating layer on the base material surface to be laminated, and hot press molding, the copper foil of the circuit portion breaks the cured resin layer, The printed wiring board includes a capacitor circuit embedded in the semi-cured resin layer and embedded in the insulating resin layer.
C) Copper in which the copper foil layer is located on the outer layer by hot pressing molding the resin layer surface of the copper foil with dielectric layer on the circuit surface embedded in the printed wiring board having the capacitor circuit. It is a tension laminate.
D) forming an etching resist layer on the outer layer copper foil, exposing and developing the capacitor circuit pattern, etching the copper foil surface to form a capacitor circuit, and peeling the resist layer, A capacitor circuit is formed, and a printed wiring board provided with the capacitor circuit is obtained. The method for producing a printed wiring board according to claim 1, wherein the skeleton material constituting the semi-cured resin layer is a nonwoven fabric or a woven fabric, and is made of glass fiber or organic fiber. The method for producing a printed wiring board having a capacitor circuit according to claim 2, wherein the resin layer constituting the copper foil with a dielectric layer contains a dielectric filler. The printed wiring board manufactured by the manufacturing method in any one of Claims 1-4.

Images