JP5005427B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

The present invention relates to a printed wiring board and a manufacturing method thereof, and more particularly to a manufacturing method of a multilayer printed wiring board in which a coil having an inductance is formed.

  In recent years, a reduction in the mounting area of circuit elements has been demanded from the demand for miniaturization and higher density of printed wiring boards. The number of circuit elements mounted on one printed wiring board is increasing year by year, and the mounting area of these circuit elements is a major obstacle to downsizing of the printed wiring board.

  Circuit elements mounted on the printed wiring board are diverse, such as semiconductor integrated circuits such as IC and LSI, chip capacitors and chip coils, chip resistors, and the like. Taking a conventional chip coil as an example, the smallest size is about 0.6 mm x 0.3 mm. The printed size of the solder paste used for mounting, the size of the component mounting land, and the adjacent component mounting land In consideration of a pattern gap for electrically insulating with each other, the mounting area per element is about 1.1 mm × 0.6 mm.

  Even if the size of the circuit element is reduced, the mounting area of the circuit element is further reduced due to limitations in solder mounting, solder resist layer formation accuracy on the surface of the printed wiring board, and circuit pattern formability. It was difficult to do. In addition, there are restrictions on the functions that can be obtained with a small circuit element. For example, when a larger inductance is required, a larger chip coil is required. For these reasons, it is desired to incorporate a passive element such as a coil in a printed wiring board to reduce the mounting area of the circuit element.

  FIG. 3A is an example of a circuit diagram of a portion that supplies power to a semiconductor integrated circuit mounted on a conventional printed wiring board. In this example, a coil element having inductance is used for a connection portion to the power supply layer. This is to prevent high-frequency noise generated from the semiconductor integrated circuit from flowing into the power supply layer and efficiently bypass it to the GND layer.

  Such a printed wiring board is usually produced by the following steps. That is, first, as shown in FIG. 4A, double-sided printed wiring having wiring patterns 72 and 73 on both surfaces of an insulating base material 71 such as polyimide, and interlayer connection by bottomed via holes 74 and 75 filled with via fill plating. A plate 76 is prepared.

  Next, as shown in FIG. 4 (2), a single-sided copper-clad laminate 79 having a copper foil 78 with a thickness of 18 μm on one side of an insulating base material 77 such as polyimide, and an interlayer adhesive sheet 80 with a thickness of 80 μm. Then, the both sides of the double-sided printed wiring board 76 are laminated by a vacuum press or the like.

  Next, as shown in FIG. 4 (3), a conformal mask for laser processing is formed on the copper foil 78 surface of the single-sided copper-clad laminate 79 by a normal photofabrication technique, and laser processing is performed using this. And conducting holes having a diameter of about 100 to 150 μm are formed. Subsequently, as pre-processing for obtaining interlayer connection by electrolytic plating, desmear processing and conductive processing are performed, and then electrolytic plating is performed to form via holes 81, 82, and 83 to achieve interlayer conduction.

  Subsequently, as shown in FIG. 4 (4), wiring circuits 78a and 78b are formed on the surface copper foil 78 and plated copper by an etching method using a normal photofabrication method, and a solder resist layer 84 is formed. . If necessary, surface treatments such as solder plating, nickel plating, and gold plating are applied to the terminal surfaces of component mounting lands and connectors.

  At this time, the inner-layer bottomed via hole 74 and the via hole 81 connected thereto are used as a power supply layer, and the inner-layer bottomed via hole 75 and the via hole 82 connected thereto are used as a GND layer. At this time, the wiring circuit 78a forms the following wiring pattern.

  FIG. 4 (5) is a conceptual plan view of the wiring circuit 78a, and its C-C ′ cross section corresponds to FIG. 4 (4). Component wiring lands 91 to 96 are formed in the wiring circuit 78a. The chip coil 97 is solder-mounted on the component mounting lands 91 and 92, and the chip capacitor 98 is solder-mounted on the component mounting lands 93 and 94, respectively. . In addition, by mounting the semiconductor integrated circuit 99 on the component mounting lands 95 and 96, a circuit as shown in FIG. 3A can be formed.

  By mounting chip capacitors, chip coils, etc. on each power supply terminal in this way, the circuit element mounting area becomes enormous, and as a result, it is difficult to reduce the size of the printed wiring board, and the semiconductor integrated circuit Wiring around the circuit board becomes complicated, and the complicated wiring itself occupies an area on the printed wiring board.

  On the other hand, as a method of forming a passive element such as a coil inside a printed wiring board, there is a method of using a zigzag or spiral wiring pattern (Patent Document 1). And it is said that inductance can be added to a circuit by forming such a wiring pattern.

  However, the inductance obtained by such a wiring pattern is very small, and the occupied area on the printed wiring board is large, which is contrary to miniaturization and high density.

  Further, as a method of forming a wiring pattern capable of obtaining a larger inductance inside the printed wiring board, Patent Document 2 discloses that a spiral wiring pattern is formed over each layer of the multilayer printed wiring board, and a spiral wiring pattern is formed at the center. A method of forming electrically isolated through holes or magnetic materials is described.

However, even in such a method, the area occupied by each built-in coil element is large, which is contrary to miniaturization and high density, and does not solve the problem.
JP-A-9-139573 JP 2005-340777 A

  As described above, the mounting area of the circuit element is an obstacle to the miniaturization and high density of the printed wiring board. Even if the circuit element is reduced in size, it is mounted by soldering and the surface layer of the printed wiring board. Therefore, it is difficult to reduce the mounting area of the circuit element any more because there is a limit to the formation accuracy of the solder resist layer, the formability of the circuit pattern, and the like.

  In addition, there is a limit to the inductance that can be obtained with a small chip coil, and when a larger inductance needs to be obtained, a larger chip coil is required. For these reasons, it is desired to incorporate a passive element such as a coil in a printed wiring board to reduce the component mounting area.

The present invention has been made in consideration of the above-mentioned points, and by forming a coil element having sufficient inductance inside the printed wiring board, the component mounting area can be greatly reduced, and a small and high-density multilayer printed wiring. An object is to provide a method for producing a plate inexpensively and stably .

In order to achieve the above object,
A method of manufacturing a printed wiring board in which a coil having inductance is formed, comprising: a) forming a spiral wiring pattern and a land portion electrically connected to a center of the wiring pattern; b) the land portion Forming a hole for forming a conductive magnetic body portion electrically connected to the land, and c) forming a conductive magnetic body portion electrically connected to the land portion in the hole. In the method of manufacturing a printed wiring board characterized by:
In the step of forming the conductive magnetic part,
When forming a nickel body using electrolytic nickel plating inside the hole, power is also supplied from a spiral wiring pattern formed on the inner electrode layer, a method for producing a multilayer printed wiring board ,
I will provide a.

  According to the present invention, a coil element having a surface layer occupation area of only 350 μm in diameter is formed inside a printed wiring board while ensuring a sufficient inductance, and the component mounting area is greatly reduced, enabling high density and downsizing. A multilayer printed wiring board is provided.

  In addition, a multilayer printed wiring board that can be miniaturized at a high density can be manufactured inexpensively and stably.

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

1 (1) to (4) are explanatory views showing the basic structure of a planar coil and its electromagnetic action. Of these, FIG. 1A is a conceptual diagram of a planar coil in which a wiring pattern is formed in a spiral shape. When a current I flows through the coil, a vortex current forms a magnetic field, and a magnetic flux Φ proportional to the current I passes through the center of the coil. When the magnetic flux Φ passing through the coil changes with time, an electromotive force V in the reverse direction proportional to the number of turns N of the coil is generated in the spiral wiring pattern (Formula 1 below).

Since the magnetic flux Φ is proportional to the current I, the above equation 1 is expressed as the following equation 2 using the proportionality constant L.

  This proportional constant L is called a self-inductance of the coil (hereinafter referred to as inductance), and acts on the alternating current like a resistance proportional to the frequency ω. It is generally known that when a magnetic core is formed at the center, a large magnetic flux Φ can be obtained for the same current I, so that the inductance of the coil can be increased.

  When calculating the inductance of a planar coil having a spiral wiring pattern, it is desirable to approximate the spiral wiring pattern with a plurality of circumferential wiring patterns.

When the current I flows on the circumference of the radius R, the strength H of the magnetic field generated near the center by the current I is expressed by the following formula 3, where the center area of the coil is S and the vacuum permeability is μ _0. Then, the magnetic flux Φ penetrating through the center of the coil is expressed by the following formula 4.

When the spiral wiring pattern is formed N times, the radius R _k of the k-th circular current can be expressed by the coil center radius R ₀ and the wiring pitch: P. It can be expressed as the sum of the magnetic fluxes produced by the current (Formula 5 below).

From the sum of the magnetic fluxes and the above equation 1, the inductance L of the N-turn coil is calculated as in the following equation 6.

Here, when the design value of the first embodiment (the following formula 7) is substituted into the above formula 6 and a specific inductance is calculated, 25.7 [nH] is obtained.

FIG. 1B is a conceptual diagram when a magnetic material is formed at the center of a spiral wiring pattern. The magnetic flux density B of the magnetic body portion, the strength of the magnetic field H, is expressed relative permeability of the magnetic material as shown in Equation 9 as mu, if the formation radius of the magnetic body and the R _B, a circle of radius R The magnetic flux Φ through which the current I passes through the center of the coil is expressed by the following formula 10.

If this is used, the inductance when the magnetic body is formed at the center of the N-turn coil is calculated as in the following equation (11).

In the first embodiment, a nickel body is used as the magnetic body. When the relative permeability is μ≈600 and the coil design value (the following formula 12) is substituted, the coil inductance is calculated to be 1217 [nH]. .

  In general, considering that the inductance of the chip coil used for the printed wiring board is about 1 to 300 [nH], this design value (the size of the coil) can sufficiently handle practically, There is no need to increase the size of the magnetic material or form a spiral wiring pattern over each layer of the multilayer printed wiring board.

  Thus, by forming a magnetic body at the center of the spiral wiring pattern, the inductance of the coil can be greatly increased. Further, in the present invention, electrical connection between layers is also performed by using a conductive material for the magnetic material. This eliminates the need for an interlayer connection element that has been separately provided in the prior art, and can significantly reduce the area occupied by the coil elements required to ensure practically required inductance.

  2A and 2B are conceptual cross-sectional views showing the manufacturing process of the printed wiring board according to the present invention. This printed wiring board is manufactured by the following steps. That is, first, as shown in FIG. 2A (1), double-sided copper-clad having copper foils 2 and 3 having a thickness of about 6 μm on both surfaces of an insulating base material 1 made of epoxy, polyimide, etc. and having a thickness of about 50 μm. A laminated plate 4 is prepared.

  The material of the insulating base material 1 is not limited to epoxy and polyimide, and can be used properly according to the application. For example, in an application where it is necessary to reduce dielectric loss during high-speed signal transmission, a double-sided copper-clad laminate based on a liquid crystal polymer or the like can be used as a low dielectric loss tangent material. The double-sided copper-clad laminate 4 is a base material corresponding to the inner layer core of the multilayer printed wiring board.

  Next, as shown in FIG. 2A (2), a conductive hole having a diameter of about 50 to 100 μm is formed on the double-sided copper-clad laminate 4 using a direct laser processing method such as a UV-YAG laser, and then conductive. The interlayer connection portion 5 is formed by performing the chemical treatment and via fill plating, and the electrical connection between the layers is performed.

  This laser processing is not limited to the direct laser processing method, but can be replaced by a conformal laser processing method or the like. In this plating process, the copper foil on one side of the double-sided copper-clad laminate 4 (here, the copper foil 2 side) is made plating-free by masking on one side or energizing only from one side. This is because it becomes advantageous when forming a fine vortex wiring pattern in the later coil formation.

  The interlayer connection portion 5 is not limited to a bottomed via hole filled with via fill plating, and a connection with a bottomed via hole by ordinary electrolytic plating or a general through hole can also be used. Through the above steps, the double-sided copper-clad laminate 6 with the interlayer connection is obtained.

  Next, as shown in FIG. 2A (3), wiring patterns 2a and 3a are formed by an etching method using a normal photofabrication method.

  FIG. 2A (4) is a conceptual plan view of the wiring pattern 2a formed on the copper foil 2 side of the double-sided copper clad laminate 6, and the A-A ′ cross section corresponds to FIG. 2A (3). In order to add inductance to the circuit, it is desirable to form the spiral wiring pattern 7 as described above. A land 8 having a diameter of about 300 μm for interlayer connection later is formed at the center of the spiral wiring pattern 7. Provide.

  Since the inductance added to the circuit is qualitatively proportional to the square of the number of turns N of the spiral wiring pattern 7, it is desirable to increase the number of turns N in order to obtain a large inductance.

  Such a spiral wiring pattern is preferably formed on the inner electrode layer of the multilayer printed wiring board in order to reduce the component mounting area on the surface layer of the printed wiring board. A plating-less structure in which can be formed is advantageous.

  In Example 1, since the interlayer connection portion 5 is a via hole formed by via fill plating, it is not necessary to consider the tent property of the dry film resist, and a high-resolution thin dry film resist can be used. Since the foil 2 side is plating-free, a fine wiring with a pitch of 30 μm can be formed in combination with a thin thickness of 6 μm. As a result, a spiral wiring pattern 7 having a diameter of 960 μm was formed with the number of turns N = 11. Thereby, the area which a coil occupies for the layer of the wiring pattern 2a becomes very small with a diameter of 1000 micrometers or less.

  Further, the wiring pattern 3a facing the spiral wiring pattern 7 only needs to be removed by etching the pattern of the portion 3b facing the land 8, and in this case, the area occupied by the coil in the layer of the wiring pattern 3a is the diameter. The region is only 300 μm. Through the above steps, the double-sided printed wiring board 9 on which the wiring pattern is formed is obtained.

  Next, as shown in FIG. 2A (5), an interlayer adhesive sheet 21 and a single-sided copper-clad laminate 22 are laminated on both sides of a double-sided printed wiring board 9 on which a wiring pattern is formed, and heating and pressing are performed. Thus, the double-sided copper-clad laminate 9 and the single-sided copper-clad laminate 22 are bonded together. At this time, since no wiring pattern is formed on the single-sided copper-clad laminate 22 to be laminated, alignment by lamination is unnecessary.

  As the interlayer adhesive sheet 21, for example, an adhesive sheet such as acrylic and epoxy having a thickness of 80 μm can be used. As the single-sided copper-clad laminate 22, one having a copper foil 24 with a thickness of 18 μm on one side of an insulating base material 23 with a thickness of about 50 μm such as epoxy or polyimide can be used.

  In addition, the material of the insulating base material 23 is not necessarily limited to epoxy and polyimide, and can be properly used according to the application. For example, a copper-clad laminate based on a liquid crystal polymer or the like can be used as the low dielectric loss tangent material.

  When a flexible cable portion is manufactured at the same time, a flexible polyimide cover film or the like is interposed between the double-sided copper-clad laminate 9 and the single-sided copper-clad laminate 22 with an adhesive sheet 21 or the like. It is also possible to perform lamination in advance on the necessary portions of the respective base materials by sandwiching them, aligning them and stacking them.

  Furthermore, a double-sided copper-clad laminate can be used in place of the single-sided copper-clad laminate 22. In that case, it is necessary to form a wiring pattern in advance on the surface of the double-sided copper-clad laminate that is to be bonded with the adhesive. The multilayer wiring substrate 25 is obtained through the above steps.

  Next, as shown in FIG. 2A (6), a conformal mask for performing conformal laser processing is formed on the copper foil 24 of the multilayer wiring substrate 25 by an etching method using a normal photofabrication method. Subsequently, carbon dioxide laser processing is performed on the conformal mask to form a conduction hole 26 having a diameter of about 100 to 150 μm. A through hole 27 having a diameter of about 100 μm is formed by drilling in a portion corresponding to the land 8 of the inner layer.

  The through hole 27 is a conduction hole for increasing the inductance added to the circuit by filling a conductive magnetic part such as nickel later, and at the same time making an electrical connection between the layers.

  Such a hole for filling the conductive magnetic body part has a purpose of increasing the inductance of the coil element. Therefore, it is desirable to form a hole extending over three layers of the multilayer printed wiring board. In addition, it is advantageous to form the holes from the surface layer after stacking because the volume of the conductive magnetic part to be filled later is larger than the formation of such holes only in the inner layer.

  The series of hole formation is not limited to drilling, and carbon dioxide laser processing, UV-YAG laser processing, or the like is used alone or in combination in consideration of required throughput, processing accuracy, and quality. be able to. Through the above steps, the multilayer wiring substrate 28 in which the holes for conduction are formed is obtained.

  Next, as shown in FIG. 2B (7), a desmear process for removing smear generated by the laser process is performed on the multilayer wiring substrate 28 in which the holes for conduction are formed, followed by a conductive process. After that, a dry film resist 29 is laminated on both surfaces of the substrate, and then exposure and development are performed, so that portions other than the through holes 27 are masked by the dry film resist 29.

  At this time, considering the exposure position deviation, the opening of the dry film resist 29 is about 250 μm in diameter with respect to the through hole 27 having a diameter of about 100 μm (a deviation of 75 μm on one side is allowed). A structure that can tolerate this degree of deviation can be adequately handled by a general-purpose exposure machine, and an expensive high-precision exposure machine is not necessary.

  As a result, the area occupied by the coil on the surface layer of the printed wiring board is very small with a diameter of 250 μm, and the occupied area is only about 350 μm in diameter even when a gap with an adjacent pattern is taken into consideration.

  It is technically possible to reduce this accuracy to about 10 μm on one side by combining processing position recognition by image processing, direct exposure by a direct drawing exposure apparatus, etc., and adjacent pattern gaps can be narrowed further. For example, the area occupied by the coil can be suppressed to a diameter of 200 μm or less.

  Then, the inside of the through-hole 27 is filled with the nickel body 30 by depositing about 30 μm of nickel body, which is a conductive magnetic body portion, by electrolytic nickel plating. At this time, in addition to feeding from the copper foil 24, feeding is also performed from the inner layer wiring pattern 2a, so that nickel plating is first deposited on the inner layer portion of the through hole 27, whereby a void or the like is formed inside the through hole 27 It can be filled stably without generating.

  In addition to the nickel body, for example, various conductive magnetic materials such as iron, cobalt, or alloys thereof can be used for the material of the conductive magnetic body portion depending on the application.

  Next, as shown in FIG. 2B (8), the dry film resist 29 is peeled off, and if necessary, conductive treatment is performed again, followed by electrolytic copper plating of about 15 to 20 μm to form a via hole 31. . At this time, in the case where other parts are mounted across the nickel body 30, the protruding portion of the nickel body 30 may be a problem.

  In that case, it is possible to ensure the flatness of the printed wiring board by performing a separate polishing process or the like immediately after the dry film resist 29 is peeled off. As this polishing process, a CMP process using an etchant that has low corrosiveness to copper and that selectively etches nickel, such as an etchant containing hydrogen peroxide or nitric acid, is desirable. Can be selectively removed.

  Next, as shown in FIG. 2B (9), etching by a normal photofabrication method was performed to form wiring circuits 24a and 24b, and then a solder resist layer 32 was formed. In this etching, it is desirable to use an etchant that has low corrosiveness to nickel and that selectively etches copper, for example, an alkaline etchant containing ammonia, so that the copper land 24c can be formed on the nickel body 30. .

  At this time, the coil formed inside the printed wiring board only occupies the surface layer of the printed wiring board only at the portion of the nickel body 30, and even if the gap with the adjacent pattern is taken into consideration, the occupied area is slight. The diameter is about 350 μm.

  Further, in the case where an etching solution used in a normal copper etching step, such as an etching solution containing cupric chloride, is used in the above etching step, the copper land 24c is removed from the nickel body so that the nickel body 30 is not removed. It is necessary to expand to a size that covers the entire surface of 30.

  In order to realize the circuit as shown in FIG. 3A, for example, the wiring circuit 24a is shaped as follows. Hereinafter, a pattern connected to the inner layer wiring pattern 2a and the nickel body 30 is referred to as a power supply layer, and a pattern connected to the inner layer interlayer connection portion 5 and the via hole 31 is referred to as a GND layer.

  FIG. 2B (10) is a conceptual plan view of the wiring circuit 24a, and a B-B ′ cross section corresponds to FIG. 2B (9). Component wiring lands 51 to 54 are formed in the wiring circuit 24a.

  A semiconductor integrated circuit 55 such as an IC is mounted on the component mounting lands 53 and 54, and power for driving the semiconductor integrated circuit 55 is supplied. A chip capacitor 56 is solder mounted on the component mounting lands 51 and 52.

  The chip capacitor 56 has a meaning of bypassing high-frequency noise generated by the semiconductor integrated circuit 55 to the GND and suppressing a power supply voltage drop caused by the switching operation of the semiconductor integrated circuit 55. Further, the component mounting land 51 is connected to the power supply layer 2a through the nickel body 30 through the inner spiral wiring pattern 7, thereby realizing the circuit configuration shown in FIG.

  Through the above process, a coil element whose surface layer occupation area of the printed wiring board is only 350 μm in diameter is formed inside the printed wiring board, and the component mounting area is greatly reduced, enabling high density and downsizing. The wiring board could be manufactured inexpensively and stably.

  The inductance of the coil portion of the printed wiring board with a built-in coil was measured and the effect was confirmed. FIG. 3B shows the measurement results of n = 50 samples in the case where nickel is formed at the center of the spiral wiring pattern and in the case where through-hole connection is performed using normal electrolytic copper plating. The measurement voltage was 5 [v] and the measurement frequency was 100 [kHz].

  As shown in FIG. 3 (2), when the center of the spiral wiring pattern is connected by a Cu through hole, the inductance of the coil is about 20 to 50 [nH], but the nickel body which is a conductive magnetic part. It can be seen that the inductance increases to about 200 to 500 [nH]. The increase width is small compared with the increase width predicted from the above formula 6 and the above formula 11, but the inductance can be increased at least three times even if the variation is taken into consideration.

  In the calculation according to the above equation 11, the influence of the height of the magnetic material is ignored, but the case where this is taken into account is described below.

Therefore, returning to FIG. 1 again, FIG. 1 (3) shows that the strength H of the magnetic field formed when the current I flows in a circular shape with a radius R is relative to the Z axis passing perpendicularly through the center of the circumference. It is a conceptual diagram showing what kind of dependency is shown. The magnetic field strength H on the central Z-axis can be calculated by the following equation (13).

This shows the dependence of the chevron that becomes maximum when Z = 0, and the maximum value is set to 1 and plotted against Z / R (the aspect ratio of the height Z to the coil radius R). 1 (4). Since the effect of forming a magnetic body of finite height is considered to be proportional to the magnetic field strength H of the portion where the magnetic body is formed, the portion of the portion where the magnetic body is formed in FIG. It is necessary to find the area. The above equation 13 can be integrated as the following equation 14 by variable conversion with Z / R = tan θ.

As a result, the influence ratio when a magnetic body having a finite height h is formed with respect to the case where a magnetic body having an infinite height is formed can be calculated as shown in the following formula 15 (the magnetic body is -h / 2 <Z <. h / 2 range).

By substituting this influence ratio into the above equation 10, the following equation 16 is obtained by obtaining the magnetic flux Φ through which the circular current I having the radius R passes through the center of the coil when a magnetic material having a finite height is formed.

If this is used, the inductance in the case where a magnetic material having a finite height is formed at the center of the N-turn coil as described above is calculated as shown in Equation 17 below.

Since the height of the magnetic body in Example 1 is about 400 μm, the coil inductance is calculated as 708 [nH] by substituting those coil design values (the following formula 18).

  Thus, when a magnetic body having a finite height is formed, the obtained inductance is reduced in calculation, and supports the measurement result of Example 1.

  Calculated and measured values depend on various other factors such as differences due to approximation used in other parts, process variations of the above design values, permeability of nickel bodies formed by electrolytic plating, frequency dependence, etc. The absolute value is considered to remain a difference.

FIGS. 1A to 1D are a conceptual diagram of a planar coil using a spiral wiring pattern, and a conceptual diagram of the dependence of a magnetic field H on the Z direction. 2A (1) to (6) are a conceptual cross-sectional view and a plan view of the structure and manufacturing method of the printed wiring board of the present invention. 2B (7) to (10) are a conceptual cross-sectional view and a plan view of the structure and manufacturing method of the printed wiring board of the present invention. FIGS. 3A and 3B are a circuit diagram showing an example of a circuit for supplying power to a semiconductor integrated circuit, and a characteristic diagram showing measurement data obtained by an embodiment of the present invention. 4 (1) to (4) are a conceptual cross-sectional view and a plan view of a conventional multilayer printed wiring board structure and manufacturing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation base material about 50 micrometers 2 Copper foil 2a about 6 micrometers thick Wiring pattern 3 Copper foil 3a about 6 micrometers thick Wiring pattern 3b Wiring pattern removal part facing a land 4 Double-sided copper clad laminated board 5 Interlayer connection part 6 Double-sided copper-clad laminate with interlayer connection 7 Spiral wiring pattern 8 Land 9 Double-sided printed wiring board 21 with wiring pattern formed Interlayer adhesive sheet 22 Single-sided copper-clad laminate 23 Insulation base material with a thickness of about 50 μm 24 Copper foils 24a and 24b having a thickness of about 18 μm Wiring circuit 24c Copper land 25 Multilayer wiring substrate 26 Conductive hole 27 Through hole 28 Multilayer wiring substrate 29 having a conductive hole formed Dry film resist 30 Nickel body 31 Via hole 32 Solder resist layers 51 to 54 Component mounting lands 55 Semiconductor integrated circuit 56 Chip capacitor 71 Insulating base material 72 , 73 Wiring pattern 74, 75 Bottomed via hole 77 Insulating base material 78 Copper foil 79 having a thickness of 18 μm Single-sided copper-clad laminate 80 Interlayer adhesive sheet 81, 82, 83 Via hole 84 Solder resist layers 91-96 Land 97 for component mounting Chip coil 98 Chip capacitor 99 Semiconductor integrated circuit

Claims (2)

A method of manufacturing a printed wiring board in which a coil having inductance is formed, comprising: a) forming a spiral wiring pattern and a land portion electrically connected to a center of the wiring pattern; b) the land portion A step of forming a hole for forming a conductive magnetic body portion electrically connected to the land, c) a step of forming a conductive magnetic body portion electrically connected to the land portion in the hole,
In a method for manufacturing a printed wiring board characterized by comprising:
In the step of forming the conductive magnetic part,
A method for producing a multilayer printed wiring board , wherein power is also supplied from a spiral wiring pattern formed on an inner electrode layer when a nickel body is formed inside the hole using electrolytic nickel plating . In the manufacturing method of the multilayer printed wiring board of Claim 1 ,
In the step of forming the conductive magnetic part,
In the hole, a nickel body is formed over at least three layers including the surface layer of the multilayer printed wiring board by using electrolytic nickel plating, and at the same time, an electrical connection between the layers is performed by the nickel body. A method for manufacturing a wiring board.

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