JP2007288022A - Multilayer printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board where an insulating material is covered in a gap and surrounding of a thick circuit pattern in a state of high quality and can inhibit a peeling defect. <P>SOLUTION: The multilayer printed wiring board manufacturing method, in which a thick circuit pattern 5 is located in an inside layer portion of a printed wiring board, includes a process which sticks a multilayer printed wiring board, that is composed of one interlayer insulator where an insulator 2 between the thick circuit pattern 5 and a conductor layer of an upper layer is formed by uniting a resin located in the gap and surface of the thick circuit pattern 5, and a copper foil thicker than upper/lower surface with an insulating as a center in advance, a process which forms a circuit of a thick copper foil to form a circuit pattern, a process which applies a resin on a gap and surface of the circuit pattern, a process which keeps the resin covered in the gap and surface of the circuit pattern in a semi-harden state, and laminates a sheet-like resin and a copper foil on the resin in order, and unites the laminated layers by heating, and process which locates a connection via on the circuit pattern to connect with a conductor of the upper layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multilayer printed wiring board having a thick conductor used for heat dissipation and a method for manufacturing the same, and in particular, even when a thick conductor is used, the conductor is well coated with an insulating material. In addition, the present invention relates to a multilayer printed wiring board in which vias connected to conductors are provided in a stable state and a method for manufacturing the same.

  In recent years, electronic parts typified by LEDs (light emitting diodes) and power transistors have been frequently used from the viewpoint of convenience. However, since electronic components represented by the LED or the like generate heat, in order for the electronic components to function properly in the electronic device, it is necessary to dissipate the generated heat source with an appropriate medium. The

  Conventional electronic devices have been designed to solve heat dissipation problems by forming a heat sink by combining heat dissipation fins, fans, and Peltier elements or a combination of them in the vicinity of the heat generating components. Technical development has been made on a printed wiring board having a so-called heat dissipation function, in which the heat-generating component can be radiated by the printed wiring board.

  Conventional printed wiring boards having a heat dissipation function have been manufactured according to the layout diagram shown in FIG. That is, the insulating resin 72 and the copper foil 73 are stacked from above the base substrate 70 having the circuit pattern 71 having a high thermal conductivity and serving as a heat radiating portion or a heat transfer portion, and the circuit pattern 71 is pressure-bonded by lamination. It was a printed wiring board of the structure which introduce | transduces into the inside of a printed wiring board.

  However, the circuit pattern 71 requires a thick conductor of, for example, about 105 μm in order to realize the function of heat dissipation or heat transfer, and when that conductor is used, as shown in FIG. When the insulating resin 72 and the copper foil 73 are stacked, the gap 75 may remain around the circuit pattern 71.

  The location of the gap 75 has been regarded as a problem because it tends to cause an electrical short circuit failure and deteriorates the quality of the printed wiring board.

  The defect in which the gap 75 remains is caused in a general printed wiring board having a conductor circuit thickness of about 20 to 40 μm because the volume serving as a gap portion of the conductor is small and can be sufficiently embedded with an insulating resin. Hateful. However, when a thick circuit pattern for heat dissipation is used, the resin component of the insulating resin 72 cannot embed the conductor gap 74, and therefore, the gap 75 is more likely to be generated than a general printed wiring board. Therefore, this defect is a unique problem of the heat-radiation type printed wiring board having a thick conductor circuit.

  In addition, as shown in FIG. 5B, since the resin component of the insulating resin 72 is accommodated in the conductor gap portion 74 of the thick conductor, there is a problem that flatness is impaired on the surface portion of the printed wiring board. It was. Further, in the case of stacking only with the insulating resin 72, it becomes difficult to control the film thickness between the layers, the thickness between the layers varies, and there is a problem because the mounting stability is insufficient when mounting on the surface portion of the electronic component. It was a thing.

  Further, as shown in FIG. 5C, a connection via 77 is provided between the copper foil 73 on the surface and the circuit pattern 71 as a heat dissipation path for heat generated from the electronic component. Since the component fits in the gap portion of the thick conductor and the depth dimension of the connection via 77 varies, it is difficult to form the connection via 77.

  On the other hand, as a means for embedding the conductor gap 74, there is a method of using an insulating resin 72 having a corresponding thickness. As an example, when a member having a thickness of 105 μm is used for the conductor circuit 71, a member having a thickness of about 150 μm is used for the corresponding insulating resin 72 (not illustrated).

  However, in this case, since a thick insulating resin 72 is used, the thickness of the resin between the circuit pattern 71 provided with the connection via 77 and the upper copper foil 73 is increased, so that there is a depth. It is necessary to form the connection via 77, and it is difficult to form the connection via 77 by this means.

  Against such a background, there has been reported a technique relating to a method for manufacturing a printed wiring board, as shown in FIG. 6, in which a gap portion of a conductor circuit is embedded with a resin and flattened by polishing after the resin is cured. (For example, refer to Patent Document 1 and Patent Document 2).

  That is, in this manufacturing method, as shown in FIG. 6A, the circuit pattern 81 is formed by removing unnecessary portions of the conductive layer of the wiring board formed by forming the conductive layer on the surface of the base material 80. As shown in FIG. 6B, a circuit pattern forming step, and a conductor embedding step for embedding the circuit pattern 81 by attaching a resin 82 to the surface of the wiring board, and after curing the resin 82, A printed wiring board manufacturing method that performs a polishing step of polishing and exposing the circuit pattern 81.

  According to the technique relating to the method for manufacturing the printed wiring board, as shown in FIG. 6C, the insulating material 83 and the copper foil 84 are stacked from the upper side of the circuit pattern 81 as shown in FIG. (I) The gap portion of the circuit pattern 81 can be embedded without any gap, and (ii) the surface of the printed wiring board can be formed with good flatness, whereby (iii) the connection via is formed above the circuit pattern 81. Can be formed with good stability.

  However, when the technique related to the method for manufacturing a printed wiring board is used for a thick conductor circuit, the following problems have occurred.

  The first problem is that a general printed wiring board having a circuit pattern 81 having a thickness of about 20 to 40 μm has a small volume as a gap portion of the circuit pattern 81, so that the gap portion is easily formed by the resin 82. In addition, after the resin 82 is cured, it can be flattened by polishing. However, when a thick conductor circuit for heat dissipation is used, the thickness of the circuit pattern 81 is 100 μm or more, and the volume of the gap of the circuit pattern 81 is large. There has been a problem that it is technically difficult to bury the concave structure with the resin 82.

  The second problem is that after the resin 82 is embedded in the gap portion of the circuit pattern 81, the resin is cured, and then, as shown in FIG. The later resin 82 and insulating material 83 have poor adhesion. Therefore, when the printed wiring board after the lamination shown in FIG. 6C is heated, for example, under moisture absorption conditions, there has been a problem of delamination or peeling between the resin 82 and the insulating material 83. .

  Further, in order to solve the second problem, the surface of the cured resin 82 is roughened by polishing, and then the insulating material 83 is stacked, so that the adhesiveness between the cured resin 82 and the insulating material 83 is increased. Is performed. However, this method improves the adhesion between the resin 82 and the insulating material 83, but does not necessarily improve the adhesion between the surface of the circuit pattern 81 and the insulating material 83. In particular, when a thick conductor circuit for heat dissipation is used, the area of the surface of the circuit pattern 81 is larger than that of a general circuit pattern. There was a problem that the adhesiveness of the resin deteriorated.

The third problem is that the curing of the resin 82 and the polishing process after curing are included as essential processes. As a result, the number of manufacturing processes of the printed wiring board is increased, and labor is required for process management.
Japanese Patent Laid-Open No. 9-321412 JP-A-10-65340

  The problem to be solved by the present invention based on such a background is that, particularly in a multilayer printed wiring board having a thick circuit pattern, the gap or the periphery of the thick circuit pattern is coated with a high quality state. An object of the present invention is to provide a printed wiring board and a method for manufacturing the same, which can suppress a peeling defect.

  The inventor has made various studies in order to solve the above problems. As a result, an insulating material is applied to the gap or the periphery of the thick circuit pattern, the insulating material is held in a semi-cured state, and then a sheet-like resin and a copper foil are laminated from above the insulating material. The inventors have found that if a multilayer printed wiring board is obtained, extremely good results can be obtained, and the present invention has been completed.

  That is, according to the present invention, in a multilayer printed wiring board in which a thick circuit pattern is disposed in an inner layer portion of the printed wiring board, an insulator between the thick circuit pattern and an upper conductor layer is A multilayer printed wiring board comprising a single interlayer insulator formed by integrating a resin provided on the gap and surface of a simple circuit pattern and a resin provided below the upper conductor layer It solves the problem.

  Further, the present invention solves the above problems by a multilayer printed wiring board, wherein a connection via is provided in an interlayer portion between the thick circuit pattern and the upper conductor layer.

  Moreover, this invention solves the said subject with the multilayer printed wiring board characterized by the thickness of the said thick circuit pattern being 100-1000 micrometers.

  In addition, the present invention solves the above problems by a multilayer printed wiring board characterized in that a glass cloth is impregnated inside a resin provided under the upper conductor layer.

  The present invention also includes a step of pasting thick copper foils from the upper and lower surfaces around an insulating material in advance, a step of forming a circuit by forming a thick copper foil circuit, and a resin in gaps and surfaces of the circuit patterns. And a step of holding the resin coated on the gap and the surface of the circuit pattern in a semi-cured state, sequentially stacking sheet-like resin and copper foil on the resin, and integrally forming by laminating heating, And a step of providing a connection via on the circuit pattern to connect to an upper conductor. The method for manufacturing a multilayer printed wiring board solves the above problem.

  Further, in the present invention, the step of applying the resin to the gap and the surface of the circuit pattern is a coating method using a screen printing method or a roll coating method, and is applied by reducing pressure and then returning to atmospheric pressure. The above-mentioned problems are solved by a method for producing a multilayer printed wiring board, which is a coating method using

  In the multilayer printed wiring board according to the present invention, the step of applying the resin to the gap and the surface of the circuit pattern is a coating method using a screen printing method or a roll coating method, and is performed at atmospheric pressure. The above-mentioned problem is solved by this manufacturing method.

  In the multilayer printed wiring board of the present invention, since the insulating material is coated in a high quality state around the gap and the periphery of the thick circuit pattern, it is possible to suppress the peeling defect. Further, according to the method for producing a multilayer printed wiring board of the present invention, in a printed wiring board having a particularly thick circuit pattern, the gap or the periphery of the thick circuit pattern is coated with a high quality state, and A peeling defect can be suppressed, and in addition, a polishing step in a conventional manufacturing process can be omitted.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, as shown in FIG. 1A, a thermosetting type insulating material 2 is prepared, and the copper foil 1 is stacked from both the upper and lower surfaces with the insulating material 2 as the center. After placement, they are integrated by a laminating press to produce a main skeleton of a printed wiring board having a double-sided copper-clad laminate structure. As the insulating material 2 used here, a material containing a reinforcing material such as a glass cloth or an inorganic filler may be used in order to give the printed wiring board strength.

  Since the multilayer printed wiring board in the present invention is used for heat dissipation, the copper foil 1 uses a thick material. The selection of the thickness of the copper foil 1 is often based on parts that radiate heat, etc., but when the copper foil 1 thinner than 100 μm is used, it may not be suitable for heat dissipation, and in addition, 1000 μm When the copper foil 1 thicker than (1 mm) is used, the circuit formation of the copper foil becomes difficult because the etching solution cannot sufficiently etch the copper foil at the time of circuit formation. Therefore, as the copper foil used in the present invention, the copper foil 1 having a thickness of 100 μm to 1000 μm is used as a copper foil thickness that can be used for heat dissipation and can form a thick conductor circuit. For example, a copper foil 1 having a thickness of 105 μm is preferably used.

  For example, when the copper foil 1 having a thickness of 105 μm is used, the insulating material 2 having a sufficient thickness for supporting and fixing the copper foil is required. As an example, an insulating material 2 having a thickness of 1200 μm (1.2 mm) is preferable.

  In the state diagram shown in FIG. 1B, the copper foil 1 and the insulating material 2 on one side are extracted from the main skeleton of the printed wiring board composed of the copper foil 1 and the insulating material 2 shown in FIG. It is shown.

  Next, in order to form the circuit of the copper foil 1 shown in FIG. 1B, a resist 3 for circuit formation is attached to the surface of the copper foil 1, and the resist 3 is exposed, developed, and peeled in this order. As shown in (b), a structure in which a part of the resist 3 remains on the surface of the copper foil 1 is formed.

  In consideration of etching the thick copper foil 1, the resist 3 used here is preferably made of a thick material in order to have durability against the etching solution. Film materials are preferably used.

  Next, in the circuit formation method by the subtractive method, the copper foil 1 in the opening portion of the resist 3 is melted in the circuit formation etching process, and after the circuit formation is completed, the structure having the circuit pattern 5 shown in FIG. Get the body. In the circuit formation here, in order to etch the thick copper foil 1, it is necessary to slow down the conveyor speed in the case of a horizontal circuit formation line. For example, the circuit pattern 5 is formed from the copper foil 1 by forming a circuit at a speed of about one-half to one-third compared with the conveyor speed when forming a conventional general conductor pattern. be able to.

  Next, the structure having the circuit pattern 5 after the circuit formation shown in FIG. 1C is used, and the resin 7 is covered around the gap of the circuit pattern 5 and the periphery of the circuit pattern 5, as shown in FIG. Obtain the structure shown.

  Here, as the resin 7, for example, an insulating resin having an epoxy-based thermosetting resin or a phenol-based thermosetting resin as a base resin is preferably used. This is because the thermal characteristics such as the thermal expansion coefficient of the resin 7 are approximated to the insulating material 2 and the resin 8 described later. Moreover, in order to improve workability and the quality after embedding, the resin 7 may contain an inorganic or metal filler. This is because the thermal expansion coefficient of the cured product is reduced by containing an inorganic or metal filler material.

  The material used for the resin 7 can be suitably used, for example, an insulating resin embedded in an inner layer circuit manufactured by Taiyo Ink Co., Ltd., which is generally sold in the market.

  Further, the coating method is a method using a screen printing method or a roll coating method, and the resin 7 is coated on the gap of the circuit pattern 5 and on the surface or the periphery of the circuit pattern 5 to obtain the structure shown in FIG. However, since the circuit pattern 5 is a thick conductor, in particular, in order to apply the resin 7 to the gap portion of the circuit pattern 5, the following manufacturing method is preferable.

  As a first means for applying the resin 7, there is a method of applying the resin 7 over the entire surface from the surface of the circuit pattern 5 shown in FIG. 1C by using a screen printing method. As the specifications of the printing plate at the time of coating, for example, a specification of 100 μm linear for Tetron material, 170 μm thick at emulsion thickness 20 μm, or a specification of 100 μm linear for stainless steel material, 205 μm thick, and 20 μm emulsion thickness can be preferably used.

Moreover, as printing conditions at the time of application, it is preferable that the off-contact value is 20 mm, the squeegee speed is 4 to 6 m / min, and the gap value between the substrate and the printing plate is 1.5 mm.

  Next, heat is applied stepwise to the resin 7 after application to reduce the viscosity of the resin 7 itself, and voids and voids remaining in the resin 7 are gradually released to the outside of the resin 7.

  As the method of applying heat stepwise, for example, a screen printing method is used to apply resin 7 on one side of the surface of the printed wiring board, and then at 25 ° C. for 10 minutes, 50 ° C. for 15 minutes, and 80 ° C. Heating was performed for 30 minutes, and then the temperature of the printed wiring board was returned to room temperature. After that, the resin 7 was applied to the other side consisting of the back surface of the printed wiring board, and then the resin wiring was applied at 25 ° C. for 10 minutes. A method of heating at 110 ° C. for 15 minutes and at 110 ° C. for 20 minutes can be mentioned.

  In the state shown in FIG. 2A after heating as described above, the resin 7 can be formed in the gap and the periphery of the circuit pattern 5 without leaving any voids or voids.

  Further, the state of the resin 7 after heating is a so-called B-stage semi-cured state because it is not completely cured under the temperature condition.

  A second means for applying the resin 7 includes a method using a printing method using a pressure difference between a reduced pressure and an atmospheric pressure.

  As a specific means, first, a peelable film is laid on the stage of the printing apparatus, and the resin 7 is spread on the film. The inside is depressurized until it becomes 20 torr or less. The time required for decompression at this time is about 1 minute. By this preparation, bubbles contained in the resin 7 are released in the reduced-pressure champ.

  Next, after applying the resin 7 to a roll for applying the resin 7 to and around the gap portion of the circuit pattern 5, the application printing of the resin 7 is started.

  The resin 7 is applied and printed by a method that does not use a printing plate. First, the printed wiring board is set on the printing stage, the resin 7 is held at a side portion of the printed wiring board, and the chamber is sealed by covering with a decompression chamber. More preferably, the pressure is reduced until the pressure is reduced to 1 torr or less.

  After the reduced pressure state, the resin 7 is applied onto the printed wiring board with a printing squeegee. The coating method here is preferably performed by a printing method in which a printing squeegee is reciprocated once on a printed wiring board. That is, the purpose is to spread the required amount of the resin 7 on the printed wiring board in the forward squeegee operation, while the purpose is to flatten the resin 7 in the return squeegee operation.

  In order to optimize the above object, it is preferable to use a roll squeegee and a flat squeegee for the return path. Further, the roll moving speed here is preferably 20 to 30 mm / s, and the rotation speed of the roll itself is preferably 60 to 70 mm / s.

  Next, after the printing is completed, a pressure difference is obtained by returning the inside of the printing environment to the atmospheric pressure, and no gap or void is generated in the gap portion of the thick circuit pattern 5 by using the pressure difference. Resin 7 is applied in the state.

  After the resin 7 is applied to one side composed of the surface of the printed wiring board using the printing method, the resin 7 is heated and dried. For example, the heating and drying conditions are as follows. First, heating is performed at 80 ° C. for 30 minutes, then the temperature of the printed wiring board is returned to room temperature, and then resin 7 is formed on the other side of the printed wiring board. And a method of heating at 110 ° C. for 20 minutes after coating.

  Since the circuit pattern 5 of the present invention aims at heat dissipation, a thick conductor is used. When a thick conductor is used, a gap or void is generated in the gap portion of the circuit pattern as shown in the prior art.

  However, when using the method of applying heat stepwise as described above or the method using the differential pressure between reduced pressure and atmospheric pressure, voids and voids are produced even when a thick conductor is used. It is possible to apply a resin that does not occur.

  After the application of the resin 7 performed in the above manner, the structure shown in FIG. 2A is obtained. Here, the state of the resin 7 after the application is finished is a semi-cured state in a B stage state. That is, after the application is completed, the next manufacturing process can be performed without performing the resin heat curing process and without performing the resin polishing process.

  As the next step, the resin 8 and the copper foil 9 are laminated and arranged as shown in FIG. 2B from above the structure shown in FIG. The resin 7 and the resin 8 provided in the gap and the periphery of the circuit pattern 5 shown in a) are integrated to obtain the structure shown in FIG.

  In the structure shown in FIG. 2C, a portion indicated by a dotted line is an explanatory drawing showing an interface between the resin 7 and the resin 8. On the other hand, since the resin 7 and the resin 8 are integrated after the laminating press, the resin is mixed at the interface portion, so that a clear interface portion is not seen.

  Here, the resin 8 is preferably a resin component similar to the resin 7. This is because by performing the lamination press, the resin 7 and the resin 8 are integrated to form an interlayer insulator 10 having one stable characteristic. In addition, by using the same resin component, when the resin 7 and the resin 8 are melted by heat, they are easily compatible with each other, and there is no variation in characteristics even as a cured product after heat curing.

  Further, in order to give the printed wiring board rigidity, the resin 8 may be impregnated with a material such as glass cloth.

  The structure shown in FIG. 2 (c) performed in the above manner is obtained. This can solve the conventional problems due to the following features.

  The first feature is that the gap and the surface of the circuit pattern 5 are embedded with a resin 7 as shown in FIG. 2A, and then from above the resin 7 as shown in FIG. 2B. The point is that the resin 8 is used for lamination.

  In the method of flattening the resin 7 by a squeegee operation after applying a necessary amount of resin on the printed circuit board such as the screen printing method or the roll coating method as described above, the resin 7 and the resin 8 are both B before lamination. Due to the semi-cured state of the stage, fluidity is exhibited by heating during lamination. As a result, the resin 7 applied on the circuit pattern 5 is thin with a thickness of about several μm, and in addition to flowing, it becomes uniform in a state of being mixed with the resin 8 at the same time. Does not affect thickness control. In addition, due to the physical pressing pressure at the time of lamination, the interlayer insulating portion made of the resin 7 and the resin 8 becomes flat, and the surface of the printed wiring board is flat compared with the conventional manufacturing method shown in FIG. It can contribute to the conversion. Furthermore, it becomes possible to easily control the film thickness of the interlayer insulating portion.

  In addition, in the case of the lamination of a single resin such as a prepreg made of the conventional insulating resin 72 shown in FIG. 5, compared with the structure obtained by the manufacturing method of the present invention shown in FIG. It is possible to form an interlayer shape with no difference in variation in the thickness of the resin.

  Here, when the resin 7 is in the C-cured main-cured state, the resin 7 does not flow at the time of lamination, so that the above-described planarization and film thickness control are difficult. That is, in order to easily perform the above-described planarization and film thickness control, it is important that the resin 7 is in a semi-cured state of the B stage. The control problem can be solved, and the formation of connection vias between layers is facilitated.

  A second feature is that the state of the resin 7 after the application is finished is set to a semi-cured state in a B stage state without complete main curing. In this way, the resin 8 that is also in the B-stage semi-cured state is placed on the resin 7 and laminated and heated, so that the two resins are integrated, and at the interface portion of the resin, they are compatible when dissolved by lamination heating. Therefore, delamination and peeling do not occur. Thereby, the conventional problems, such as delamination between the resins and the problem of peeling, can be solved.

  Further, since the resin 7 is also coated on the circuit pattern 5, the adhesion is good even at the interface between the resin after the lamination and the circuit pattern 5, and there is no problem of delamination or peeling.

  As the third feature, since the resin 7 is not cured, the resin heat curing step and the polishing step after the resin heating can be omitted as a manufacturing method. Thereby, the problem of process management of the manufacturing method and its labor which are the conventional problems can be solved.

  The fourth feature is that the resin 7 is applied to the entire surface of the circuit pattern 5 in advance, and then the resin 8 is covered with a lamination press. It is possible to embed the gap by a good and simple method without generating any voids. As a result, when a thick circuit pattern for heat dissipation, which is a conventional problem, is used, it is possible to solve the problem that it is difficult to embed the gap portion of the circuit pattern 5 with resin.

  As the next step, a connection via 14 is provided on the circuit pattern 5 shown in FIG. 2C to obtain the structure shown in FIG.

  As a method for forming the connection via 14, for example, drilling of the connection via 14 portion by laser processing, cleaning in the hole, and formation of the connection via 14 by copper plating are sequentially performed.

As an example of the formation of the connection via 14 part by laser processing, the energy density per shot is set to 0.7 to 1.2 J / cm ² , 50 to 150 shots are performed, the top diameter is 100 μm, A method of forming the connection via 14 having a bottom diameter of 65 to 85 μm is mentioned. The structure shown in FIG. 3A shows a structure in which one connection via 14 is provided on the circuit pattern 5, but the number of connection vias 14 provided on the circuit pattern 5 is one. There is no limitation to this, and a plurality of connection vias 14 may be provided.

  In addition, after the formation of the hole in the connection via 14 part, the inside of the hole is cleaned. In this cleaning, desmear treatment is preferably performed for the purpose of removing organic residues.

  Next, after the formation of the connection via 14, electroless and electrolytic copper plating 12 is sequentially performed, and the copper plating 12 is adhered to the inside and the surface of the connection via 14 portion to form the connection via 14 shown in FIG. The obtained structure is obtained.

  Next, circuit formation of the structure shown in FIG. As a circuit formation method here, a circuit can be formed by a subtractive method in the same manner as described above, and after applying a dry film, a mask for forming a desired circuit is set, exposure, development, etching, dry film Circuit formation is performed in the order of the peeling process, and the connection via 14 after the circuit formation as shown in FIG. 3B is formed.

  An overall view of the multilayer printed wiring board of the present invention manufactured in such a manner is shown in FIG.

  FIG. 4A shows a structure in which the through hole 16 is provided. In the formation method of the through hole 16, after integrating the resin 8 and the copper foil 9 by a laminating press, a through hole is formed at a desired position for forming the through hole using a drill or a router, The copper plating 12 used when the connection via 14 is provided can be formed by a conventional printed wiring board manufacturing method in which copper plating is adhered to the inside of the through hole.

  Further, on the connection via 14 shown in FIG. 4A, components such as a power IC and a power transistor that generate heat are mounted via a solder material or the like.

  The heat radiation type printed wiring board after the component is mounted is connected to the printed wiring board by transferring heat generated from the component to the lower circuit pattern 5 through the connection via 14 and drawing the circuit pattern 5. Heat can be radiated to the cooling concealment.

  Further, in the structural diagram shown in FIG. 4B, a structure obtained by impregnating the resin 8 with the glass cloth 17 when the resin 8 is integrated by a lamination press is shown. Since the rigidity of the printed wiring board is improved by impregnating the glass cloth 17, the structure shown in FIG. 4B is suitably used as the multilayer printed wiring board of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. The schematic cross-sectional process explanatory drawing which shows the manufacture example of the multilayer printed wiring board of this invention following FIG. FIG. 3 is a schematic cross-sectional process explanatory diagram illustrating a manufacturing example of the multilayer printed wiring board of the present invention following FIG. 2. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional explanatory view showing a multilayer printed wiring board according to the present invention. The schematic cross-section explanatory drawing which shows the manufacture example of the conventional multilayer printed wiring board. Schematic cross-sectional explanatory drawing which shows the manufacture example of another conventional multilayer printed wiring board.

Explanation of symbols

1: Copper foil 2: Insulating material 3: Resist 5: Circuit pattern 7: Resin 8: Resin 9: Copper foil 10: Interlayer insulator 12: Copper plating 14: Connection via 16: Through hole 17: Glass cloth

Claims (7)

  In the multilayer printed wiring board in which the thick circuit pattern is disposed in the inner layer portion of the printed wiring board, the insulator between the thick circuit pattern and the upper conductor layer has gaps between the thick circuit pattern and A multilayer printed wiring board comprising a single interlayer insulator formed by integrating a resin provided on a surface and a resin provided below an upper conductor layer.   2. The multilayer printed wiring board according to claim 1, wherein a connection via is provided in an interlayer portion between the thick circuit pattern and the upper conductor layer.   The multilayer printed wiring board according to claim 1, wherein the thick circuit pattern has a thickness of 100 to 1000 μm.   The multilayer printed wiring board according to any one of claims 1 to 3, wherein a glass cloth is impregnated in a resin provided under the upper conductor layer.   A process of pasting thick copper foils from the upper and lower surfaces around the insulating material in advance, a process of forming a circuit by forming a circuit of the thick copper foil, a process of applying a resin to the gap and the surface of the circuit pattern, A step of holding the resin coated on the gap and the surface of the circuit pattern in a semi-cured state, stacking a sheet-like resin and a copper foil sequentially on the resin, and integrally forming by laminating heating, A method of manufacturing a multilayer printed wiring board, comprising the step of providing a connection via and connecting to an upper conductor.   The step of applying the resin to the gap and the surface of the circuit pattern is a coating method using a screen printing method or a roll coating method, which is a coating method using a differential pressure by returning to atmospheric pressure after applying at a reduced pressure. The method for producing a multilayer printed wiring board according to claim 5, wherein:   6. The multilayer printed wiring board according to claim 5, wherein the step of applying the resin to the gap and the surface of the circuit pattern is a coating method using a screen printing method or a roll coating method, and is performed at atmospheric pressure. Manufacturing method.