JP4845274B2 - Wiring board and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wiring board used for a semiconductor element housing package or a hybrid integrated circuit board for housing a semiconductor element.
[0002]
[Prior art]
Conventionally, a multilayer printed wiring board is manufactured by bonding a copper foil to the surface of an insulating substrate containing an organic resin, and then etching this to form a fine wiring circuit layer, and then laminating this substrate. In addition, a solder resist layer is formed on the surface of the multilayer wiring board to prevent solder flow on the surface of the board, which is mounted by soldering when mounting electronic components.
[0003]
Such a solder resist layer is usually formed by using a photocurable solder resist layer with good processability, applying a resist to the entire surface of the substrate, exposing and developing.
[0004]
In recent years, semiconductor devices have been driven at high speed, and accordingly, driving pulses for driving the semiconductor devices also have a high frequency and an extremely short rise time. For this reason, higher-order harmonic noise is more likely to occur in the power source and signal of the semiconductor element than in the drive pulse.
[0005]
Such higher-order harmonic noise is propagated to the external electric circuit board to which the wiring board is connected through the wiring circuit layer of the wiring board on which the semiconductor element is mounted, and may adversely affect other semiconductor devices. . In addition, harmonic noise generated by other semiconductor devices is propagated to the semiconductor element mounted on the wiring board through the wiring circuit layer, causing malfunction in the semiconductor element.
[0006]
On the other hand, a material having a small loss (tan δ) is required as a material of the insulating substrate of the wiring substrate in order to cope with high-speed driving of the semiconductor element, and the insulating substrate formed by bonding the above inorganic powder with a thermosetting resin. There is a similar requirement for a wiring board comprising a wiring circuit layer formed by bonding a metal powder with a thermosetting resin, but on the other hand, when the loss (tan δ) of the material of the insulating board is reduced, the insulation is reduced. Unwanted radiation from the wiring circuit layer deposited on the surface of the substrate or on the surface is increased, and the above harmonic noise is likely to occur.
[0007]
[Problems to be solved by the invention]
However, a conventional solder resist layer processing method using a photocurable resin has many steps such as resist coating, exposure, and development, which greatly affects time and cost. Furthermore, since it is photocuring, there is a problem in reliability due to poor adhesion and curing characteristics with the insulating substrate. Moreover, although it has also been proposed to use a thermosetting resin as the solder resist layer, there is a problem that the printability is poor and it is not possible to cope with fine wiring.
[0008]
On the other hand, as an anti-noise measure, an electromagnetic shield layer is also formed inside or on the surface of the wiring board, but in addition to the normal wiring board manufacturing process, a process of forming an electromagnetic shielding layer is added. However, there are problems such as an increase in the number of processes and an increase in cost. In addition, it has been proposed to include a ferromagnetic material in the insulating layer, but the characteristics of the insulating substrate may change, which may adversely affect the characteristics of the original insulating substrate.
[0009]
Therefore, the present invention has been devised in view of such conventional drawbacks, and its purpose is to improve the processability, adhesion and curing characteristics of the solder resist layer and to suppress unnecessary radiation from the wiring circuit layer. An object of the present invention is to provide a wiring board that can effectively remove harmonic noise, hardly emit noise to an external electric circuit board, and can drive a mounted semiconductor element normally and stably at high speed. .
[0010]
[Means for Solving the Problems]
According to the present invention, the solder resist layer includes the same resin as the thermosetting resin contained in the insulating layer of the wiring board, and is formed of a composite of the inorganic powder and the ferromagnetic powder. It has been found that by improving the processability, adhesion and curing characteristics of the layer, and by providing the solder resist layer with a noise removal function, it is possible to suppress noise emission and to suppress the influence of external noise.
[0011]
  That is, the wiring board of the present invention includes the first thermosetting resin.And first inorganic powderAn insulating substrate formed by laminating a plurality of insulating layers containing, a wiring circuit layer wired on the surface and inside of the insulating substrate, and a via-hole conductor for electrically connecting the wiring circuit layers In the wiring board, on the surface of the wiring board, a second thermosetting resin,SecondInorganic powder and theSecondA solder resist layer including a ferromagnetic powder having a particle size of 1/2 or less of the particle size of the inorganic powder is formed.And
The first inorganic powder and the second inorganic powder are made of the same inorganic material, and the average particle size of the first inorganic powder is larger than the average particle size of the second inorganic powder.It is characterized by this.
[0012]
  Moreover, the manufacturing method of the wiring board of this invention is 1st thermosetting resin.And first inorganic powderA plurality of wiring sheets formed by forming via-hole conductors and wiring circuit layers on an uncured insulating sheet containing a first laminate, and then, on the surface of the first laminate, 2 thermosetting resin,SecondInorganic powder and theSecondA second laminate is produced by laminating an uncured resist sheet made of an insulator including a ferromagnetic powder having a particle size of 1/2 or less of the particle size of the inorganic powder, and having been punched. Curing the second laminate at onceA method for manufacturing a wiring board, comprising:
The first inorganic powder and the second inorganic powder are made of the same inorganic material, and the average particle size of the first inorganic powder is larger than the average particle size of the second inorganic powder.It is characterized by this.
[0013]
  In addition,SaidThe composition of the solder resist layer is 20 to 80% by weight of the second thermosetting resin,The secondIt is appropriate to contain the inorganic powder and the ferromagnetic powder in a proportion of 20 to 80% by weight in total.
[0014]
  In the wiring board and the manufacturing method thereof, the ferromagnetic powderButSaidSecondContained in a proportion of 30 to 60% by weight with respect to the total amount of inorganic powderHas beenThatWhen,SaidSolder resist layer5It is formed with a thickness of ~ 100 μmWhenBut the solder flowThePreventionDoAt the same time, it is desirable for exhibiting a noise removal effect.
[0015]
  Further, in the solder resist layerThe secondA thermosetting resin in the insulating layer;The firstThermosetting resinWhenThe same is preferable for enhancing the adhesion of the solder resist layer.
[0016]
According to the present invention, since a thermosetting resin is used as the organic resin in the solder resist layer, the glass transition temperature can be set higher than that of a conventional photocurable resin, and thermal expansion can be achieved by adding an inorganic powder. The coefficient can be easily matched to the insulating substrate, and the elastic modulus, water resistance, and moisture resistance can be improved. In particular, adhesion is improved by using the same resin as the insulating layer.
[0017]
In addition, when the solder resist layer is formed by a printing method, printability and resolution become a problem. However, in the manufacturing method of the present invention, a resist sheet is prepared in advance, and this sheet is prepared in advance and drilled. After positioning and laminating the laminated body, the thermosetting treatment is performed collectively, so that printing is not performed, so that problems such as printability and resolution due to printing can be solved. In addition, since the resist sheet contains an inorganic powder, the processability is good, punching such as punching can be easily performed, and drilling of any shape can be performed by laser processing.
[0018]
In addition, according to the wiring board of the present invention, since the insulating substrate is formed by combining inorganic powder and ferromagnetic powder with a thermosetting resin, the ferromagnetic powder absorbs unnecessary radiation from the wiring circuit layer. Harmonic noise can be effectively removed, noise emission to the external electric circuit board and noise propagation from the external electric circuit board can be suppressed, and the dielectric constant of the insulating substrate can be reduced by the inorganic powder. The wiring board can be set to a desired small value and the semiconductor element to be mounted can be driven normally and stably at high speed.
[0019]
Moreover, according to the method for manufacturing a wiring board of the present invention, by manufacturing a wiring board having the above-described configuration using a precursor sheet formed by mixing inorganic powder and ferromagnetic powder and a thermosetting resin precursor, It is possible to provide a wiring board having excellent electrical characteristics capable of normally and stably driving a mounted semiconductor element at high speed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view for explaining an example of the wiring board of the present invention, wherein 1 is an insulating substrate, 2 is a wiring circuit layer, 3 is a via-hole conductor, and 4 is a solder resist layer.
[0021]
According to the wiring board of the present invention, the insulating substrate 1 is formed by laminating the insulating layers 1a, 1b, and 1c, and the wiring circuit layer 2 is formed on each of the insulating layers 1a, 1b, and 1c. Yes. In addition, in the insulating layers 1a, 1b, and 1c, via-hole conductors 3 formed by filling through-holes with a conductor component are formed in order to electrically connect at least two wiring circuit layers 2 formed in different layers. Thus, a multilayered circuit is formed. Also, a solder resist layer 4 is provided on the surface of the wiring board, and various electronic components are mounted on the wiring circuit layer 2 exposed from the solder resist layer 4 by soldering or the like.
[0022]
The insulating substrate 1 in the present invention includes at least a thermosetting resin. Examples of the thermosetting resin include at least one selected from the group consisting of an epoxy resin, a polyimide resin, a phenol resin, a thermosetting polyphenylene ether resin, and a polyimide amide resin. The insulating substrate 1 includes at least one inorganic powder selected from the group consisting of silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, and zeolite, and / or a group of woven and non-woven fabrics such as glass fiber and aramid fiber. It is desirable to include at least one filler component selected from:
[0023]
Since the strength of the insulating substrate 1 can be increased by dispersing these filler components in the thermosetting resin, occurrence of chips, cracks, cracks, and the like due to collisions between the wiring substrates can be prevented.
[0024]
Further, if the filler component contained in the insulating substrate 1 is less than 20% by weight, the above effect of the filler component is not sufficiently exhibited, and the thermal expansion coefficient of the insulating substrate 1 is increased. In addition, when it exceeds 80% by weight, it tends to be difficult to firmly bond the filler component with the thermosetting resin. Therefore, the content of the filler component contained in the insulating substrate 1 is preferably in the range of 20 to 80% by weight, particularly 45 to 65% by weight.
[0025]
The wiring circuit layer 2 is formed of at least one metal selected from the group consisting of copper, silver, and gold. The wiring circuit layer 2 is obtained by mixing an organic resin such as an epoxy resin with these metal powders. It can be formed by printing a conductive paste or a metal foil. The via-hole conductor 3 is also filled with the same metal as described above, and the via-hole conductor 3 is formed by filling the conductor paste.
[0026]
If the content of the metal powder in the conductor paste is less than 70% by weight, the conductivity of the wiring circuit layer 2 and the via-hole conductor 3 tends to deteriorate. If the content exceeds 95% by weight, the metal powder is made of an organic resin. It tends to be difficult to bond firmly. Therefore, the content of the metal powder in the paste forming the wiring circuit layer 2 and the via-hole conductor 3 is preferably in the range of 70 to 95% by weight.
[0027]
Further, the wiring circuit layer 2 has an exposed surface with at least one selected from the group consisting of Ni and Au, and is coated with a highly conductive metal to a thickness of 1.0 to 20 μm by plating. If this is done, the oxidative corrosion of the wiring circuit layer 2 can be effectively prevented. Therefore, it is usually desirable to form a plated layer of the above metal with a thickness of 1.0 to 20 μm on the exposed surface of the wiring circuit layer 2.
[0028]
It is important that the solder resist layer 4 in the present invention contains a thermosetting resin, an inorganic powder, and a ferromagnetic powder. As the inorganic powder, at least one selected from the group consisting of silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, barium titanate, strontium titanate, calcium titanate, titanium oxide, and zeolite is selected.
[0029]
Ferromagnetic powders such as iron, nickel, cobalt, chromium oxide or alloys thereof, which are ferromagnetic materials, or Mn-Zn ferrite, Ni-Zn ferrite, Ba ferrite, Mg- Various ferrites such as Mn ferrite and Ni-Cu ferrite (MOFe₂O_Three: M is at least one powder selected from the group of divalent metal ions).
[0030]
Furthermore, examples of the thermosetting resin include at least one selected from the group of epoxy resins, polyimide resins, phenol resins, thermosetting polyphenylene ether resins, polyimide amide resins, and bismaleimide triazine resins.
[0031]
If the total content of the inorganic powder and the ferromagnetic powder in the solder resist layer 4 is less than 20% by weight, when a semiconductor element is mounted on the surface of the wiring board of the present invention, silicon, GaAs, etc. Since the difference in thermal expansion from the semiconductor element becomes large, the solder resist layer 4 is peeled off from the insulating substrate 1 due to the heat generated during the operation of the semiconductor element, or stress is generated in the mounting portion with the semiconductor element, resulting in poor mounting. Invite. On the other hand, if the content exceeds 80% by weight, it is difficult to firmly bond the inorganic powder and the ferromagnetic powder with the thermosetting resin, and the solder resist layer 4 cannot be stably formed.
[0032]
Therefore, the content of the inorganic powder and the ferromagnetic powder in the solder resist layer 4 needs to be 20 to 80% by weight, particularly 45 to 65% by weight. Further, the amount of the ferromagnetic powder relative to the total amount of the inorganic powder and the ferromagnetic powder is such that when the content of the ferromagnetic powder is less than 30% by weight, unnecessary radiation from the wiring circuit layer 2 is absorbed and the harmonics are absorbed. The effect of effectively removing noise is small, and if it exceeds 60% by weight, the bond between the magnetic powder and the resin is weak, so that the strength of the uncured sheet for forming the solder resist layer 4 becomes low, and the production The above handling may be difficult. Therefore, the content of the ferromagnetic powder is desirably 30 to 60% by weight, particularly 35 to 50% by weight, based on the total amount of the inorganic powder and the ferromagnetic powder.
[0033]
As the particle size of the inorganic powder in the solder resist layer 4 is less than 0.1 μm, the specific surface area of the inorganic powder increases, so the viscosity increases when forming a resist sheet, and the sheet body is stabilized. It tends to be difficult to form. On the other hand, if the thickness exceeds 20 μm, the surface roughness of the resist sheet becomes rough, and it tends to be difficult to form a uniform wiring circuit layer on the surface by printing metal paste or the like. Therefore, the particle size of the inorganic powder is preferably in the range of 0.1 to 20 μm.
[0034]
In addition, when the particle size of the ferromagnetic powder is less than 0.05 μm, the specific surface area of the ferromagnetic powder becomes large. Therefore, when a predetermined amount is filled, the viscosity increases when the resist sheet is formed, and the sheet body is stabilized. Tends to be difficult to form. On the other hand, when the thickness exceeds 10 μm, the surface roughness of the resist sheet becomes rough, and it tends to be difficult to form a uniform wiring circuit layer on the surface by printing a metal paste or the like. Therefore, the particle size of the ferromagnetic powder is preferably in the range of 0.05 to 10 μm.
[0035]
Furthermore, regarding the relationship between the particle size of the ferromagnetic powder and the particle size and shape of the inorganic powder, the effect of the ferromagnetic powder can be exhibited more efficiently by uniformly dispersing the ferromagnetic powder. Therefore, the particle size of the ferromagnetic powder is preferably ½ or less of the particle size of the inorganic powder, and the shape of the ferromagnetic powder is preferably spherical or polyhedral with an aspect ratio of 2 or less.
[0036]
According to the present invention, since the solder resist layer 4 has a predetermined amount of ferromagnetic powder as described above, the ferromagnetic powder converts and absorbs unnecessary radiation into heat energy and has a high magnetic permeability. For this reason, the loss (tan δ) is increased and the impedance becomes high with respect to the harmonic noise. Accordingly, unnecessary radiation is generated from the input / output signal propagating through the wiring circuit layer 2 or an output signal containing harmonic noise from the semiconductor element mounted on the wiring board is transmitted to the external electric circuit board through the wiring circuit layer 2. Even if an input signal including harmonic noise is transmitted from the external electric circuit board to the semiconductor element via the wiring circuit layer 2, unnecessary radiation or harmonic noise included in the input / output signal is strong. As a result, it is absorbed and removed by the magnetic powder, and as a result, unnecessary radiation may be generated as noise, or harmonic noise may be propagated from the semiconductor element to the external electric circuit board or from the external electric circuit board to the semiconductor element. Disappear. In order to sufficiently exhibit such an effect, the thickness of the solder resist layer is suitably 5 μm or more, particularly 20 μm or more. In terms of noise removal, there is no upper limit, but if it is too thick, a large amount of solder applied to the wiring circuit layer 2 is required, which is not desirable, and 100 μm or less is appropriate.
[0037]
Next, a method for manufacturing the above-described wiring board of the present invention will be described with reference to FIG.
[0038]
First, as shown in FIG. 2A, uncured insulating sheets 11a to 11c made of a composite of fiber or inorganic powder and a thermosetting resin are prepared. In addition, this uncured means that the hardening process is not performed or a semi-hardened state. In this insulating sheet, for example, as a filler, silicon oxide powder, potassium titanate whisker, etc., thermosetting resin such as bisphenol A type epoxy resin, and curing agent such as imidazole type curing agent. Etc.
[0039]
Each of the insulating sheets 11a to 11c is manufactured by forming the mixture into a paste and forming the mixture into a sheet by a sheet forming method such as a doctor blade method. Moreover, after forming into a sheet, the sheet can be easily handled by heating at a temperature of about 25 to 100 ° C. for 1 to 60 minutes to be semi-cured.
[0040]
Next, as shown in FIG. 2 (b), through holes are formed in predetermined locations of the insulating sheets 11a to 11c using a known punching method and laser method, respectively, and metal powder and organic are formed in the through holes. The via-hole conductor 12 is formed by filling a conductor paste containing resin.
[0041]
Thereafter, as shown in FIG. 2C, the wiring circuit layer 13 is formed on each surface of the insulating sheets 11a to 11c on which the via-hole conductors 12 are formed. The wiring circuit layer 13 can be formed in a predetermined circuit shape by screen printing using a conductor paste similar to that filled in the via-hole conductor 12. When the conductive paste is formed by printing, the via hole conductor 12 and the wiring circuit layer 13 can be formed at the same time. In addition, after forming a via-hole conductor and a wiring circuit layer with a conductor paste, it is desirable to heat and semi-harden at a temperature of about 25 to 100 ° C. for 1 to 60 minutes.
[0042]
Moreover, the wiring circuit layer 13 can also be formed with metal foil. In the case of forming with a metal foil, the metal foil is bonded to the surfaces of the insulating sheets 11a to 11c, and then etched to form a circuit, or formed into a circuit using a metal foil on a predetermined transfer film. Then, it can be transferred to the surface of the insulating sheet. This transfer method is effective in that the insulating sheet and the wiring circuit layer can be formed in parallel.
[0043]
The metal paste used as the via-hole conductor 12 and the wiring circuit layer 13 is, for example, a metal powder such as Cu having an average particle size of 0.1 to 20 μm, bisphenol A type epoxy resin, novolac type epoxy resin, glycidyl ester type epoxy resin. And a thermosetting resin such as an amine curing agent, an imidazole curing agent, and an acid anhydride curing agent. Also, in this conductor paste, a low melting point metal powder composed of tin-lead solder, etc. is blended, the low melting point metal powder is melted during the curing process, and the metal powder is bonded by the melted low melting point metal. The resistance of the circuit layer and via-hole conductor can be reduced.
[0044]
On the other hand, inorganic powder having an average particle size of 0.1 to 20 μm, ferromagnetic powder having an average particle size of 0.05 to 10 μm, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolac type epoxy resin, glycidyl Obtained by mixing at least one thermosetting resin selected from the group of ester-type epoxy resins and at least one curing agent selected from the group of amine curing agents, imidazole curing agents, and acid anhydride curing agents. The obtained paste is formed into a sheet by a sheet forming method such as a doctor blade method to produce resist sheets 14a and 14b having a thickness of 5 to 100 μm. And it is made to semi-cure suitably at the temperature of about 25-130 degreeC suitably.
[0045]
And the through-hole 15 is formed in the predetermined location with respect to this resist sheet 14a, 14b using the punching method and the laser method.
[0046]
And as shown in FIG.2 (d), while laminating | stacking insulating sheet 11a-11c in which the via-hole conductor 12 and the wiring circuit layer 13 were formed, resist sheet 14a, 14b was laminated | stacked on the upper and lower surfaces of the laminated body. Thereafter, the present invention is completed by heating the resin at a temperature at which the thermosetting resin contained in each sheet is completely cured, for example, at a temperature of 200 to 300 ° C. for about 10 seconds to 24 hours, thereby completely curing them. A wiring board can be manufactured.
[0047]
In the example of FIG. 2, the wiring board is manufactured by laminating the three insulating sheets 11a to 11c. However, the number of the insulating sheets may be four or more or one.
[0048]
【Example】
Spherical fused SiO having 35% by weight of a mixed resin of thermosetting polyphenylene ether resin and triallyl isocyanurate as the thermosetting resin and an average particle size of 5 μm₂Toluene was added as a solvent to the mixture of 65% by weight, and a catalyst for further promoting the curing of the organic resin was added and mixed. Then, an insulating sheet having a thickness of 200 μm was prepared from the slurry by the doctor blade method. A via hole conductor having a diameter of 100 μm was formed on this insulating sheet with a carbon dioxide gas laser, and a copper paste plated with silver and a conductive paste containing an epoxy resin as a binder were filled in the hole to form a via hole conductor.
[0049]
On the other hand, an electrolytic copper foil having a surface roughness (Ra) of 0.4 μm and a thickness of 12 μm was bonded to the surface of a polyethylene terephthalate (PET) resin film via an acrylic adhesive. And after applying a photosensitive resist on the surface of this copper foil and exposing through a glass mask to form a circuit pattern, this is sprayed in a ferric chloride solution to make the non-pattern part 35 μm / min. Etching was removed to form a mirror image wiring circuit layer.
[0050]
Then, the resin film on which the wiring circuit layer is formed is laminated in alignment with the surface of the insulating sheet on which the via-hole conductor is formed, and 30 kg / cm²After pressurizing at a pressure of 30 seconds, only the resin film and the adhesive layer were peeled off to transfer the wiring circuit layer to the insulating sheet. The wiring circuit layer transferred to the insulating sheet was completely embedded in the surface of the insulating sheet, and it was confirmed that the surface of the insulating sheet and the surface of the wiring circuit layer were in the same plane.
[0051]
Further, as a resist sheet, 55% by weight of a thermosetting resin made of thermosetting polyphenylene ether and spherical fused SiO having an average particle diameter of 2 μm.₂To add 25% by weight of powder and 20% by weight of Mn—Zn ferrite ferromagnetic powder having an average particle diameter of 1 μm, and add toluene as a solvent to further accelerate the curing of the organic resin After the catalyst was added and mixed to form a slurry, the slurry was processed into a sheet by the doctor blade method. As a result, a good resist sheet having a thickness of 40 μm could be produced. When this resist sheet was processed with a carbon dioxide laser, good through holes could be formed.
[0052]
Then, the insulating sheet 5 layer formed with the wiring circuit layer and the via-hole conductor produced in the same manner as described above, and a resist sheet are laminated on the uppermost surface and the lowermost surface thereof, and these are 30 kg / cm.²A wiring board was fabricated by heat treatment at 200 ° C. for 2 hours at a pressure of ˜.
[0053]
In addition, as a result of measuring a thermal expansion coefficient of 25 to 180 ° C. after thermosetting the insulating sheet and the resist sheet, 22 × 10^-6/ ° C, 25 × 10^-6It was confirmed that the characteristics approximated to / ° C.
[0054]
Also, 2000 cycles of −55 to 125 ° C. were performed on the produced wiring board, and the inner layer of the wiring board and the interface between the insulating substrate and the solder resist layer were observed. A highly reliable wiring board without any defects could be produced.
[0055]
【The invention's effect】
As described above in detail, according to the present invention, the solder resist layer has a noise removing function by forming the solder resist layer with an insulator including a thermosetting resin, an inorganic powder, and a ferromagnetic powder. Therefore, unnecessary radiation from the wiring circuit layer in the wiring board to the outside can be suppressed, harmonic noise can be effectively removed, and noise can be made difficult to be emitted to the external electric circuit board. In addition, by including inorganic powder together with ferromagnetic powder in this solder resist layer, the thermal expansion coefficient of the solder resist layer can be adjusted to an arbitrary value, and the thermal expansion characteristics of the wiring board can be matched. In addition, it is possible to improve the adhesion reliability of the solder resist layer having noise removability with the wiring substrate.
[0056]
In addition, this solder resist layer is formed by laminating a resist sheet containing a thermosetting resin, an inorganic powder, and a ferromagnetic powder, and simultaneously curing at the same time as the wiring substrate is cured. It can be easily formed and processed easily.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an embodiment of a wiring board according to the present invention.
FIG. 2 is a cross-sectional view for each step for explaining the method of manufacturing the wiring board of FIG. 1 of the present invention.
[Explanation of symbols]
1 Insulating substrate
2 Wiring circuit layer
3 Via-hole conductor
4 Solder resist layer

Claims (10)

An insulating substrate formed by laminating a plurality of insulating layers containing the first thermosetting resin and the first inorganic powder , a wiring circuit layer wired on and inside the insulating substrate, and between the wiring circuit layers in the wiring board having a via-hole conductors for electrically connecting the surface of the wiring substrate, the particle size of the second thermosetting resin, the second inorganic powder and the second inorganic powder 1 / A solder resist layer including a ferromagnetic powder having a particle size of 2 or less is formed ;
The first inorganic powder and the second inorganic powder are made of the same inorganic material, and the average particle size of the first inorganic powder is larger than the average particle size of the second inorganic powder. Wiring board. 2. The solder resist layer includes 20 to 80 wt% of the second thermosetting resin and 20 to 80 wt% in total of the second inorganic powder and the ferromagnetic powder. The wiring board described. 3. The wiring board according to claim 2, wherein the ferromagnetic powder is contained in a proportion of 30 to 60% by weight with respect to the total amount of the second inorganic powder.   4. The wiring board according to claim 1, wherein the solder resist layer is formed with a thickness of 5 to 100 [mu] m.   The wiring board according to claim 1, wherein the second thermosetting resin in the solder resist layer is the same as the first thermosetting resin in the insulating layer. After laminating a plurality of wiring sheets formed by forming via-hole conductors and wiring circuit layers on an uncured insulating sheet containing the first thermosetting resin and the first inorganic powder , a first laminate is produced. , the surface of the first laminate, comprising a ferromagnetic powder having a second thermosetting resin, the particle diameter of 1/2 or less of the particle diameter of the second inorganic powder and the second inorganic powder A method of manufacturing a wiring board comprising an insulator and a non-cured resist sheet that has been perforated to form a second laminate, and curing the second laminate in a lump .
The first inorganic powder and the second inorganic powder are made of the same inorganic material, and the average particle size of the first inorganic powder is larger than the average particle size of the second inorganic powder. A method for manufacturing a wiring board. The resist sheet includes the second thermosetting resin in a ratio of 20 to 80% by weight, and the total amount of the second inorganic powder and the ferromagnetic powder in a range of 20 to 80% by weight. A method for manufacturing a wiring board according to claim 6. 8. The method of manufacturing a wiring board according to claim 7, wherein the ferromagnetic powder is contained in a proportion of 30 to 60% by weight with respect to the total amount of the second inorganic powder.   The method for manufacturing a wiring board according to claim 6, wherein the resist sheet has a thickness of 5 to 100 μm.   The wiring according to any one of claims 6 to 9, wherein the second thermosetting resin in the resist sheet is the same as the first thermosetting resin in the insulating sheet. A method for manufacturing a substrate.

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