JPH11163483A - Wiring substrate and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring substrate, wherein unwanted radiation from it is suppressed, harmonics noise is removed effectively, noise is hardly released to an external electric circuit board, and a mounted semiconductor element is driven normally and stably at high speed, for a wiring substrate in which an insulating base body wherein inorganic insulating powder is combined with thermosetting resin is coated with a wiring conductor in which metal powder is combined with the thermosetting resin. SOLUTION: An insulating base body 1 comprising inorganic insulating powder and ferromagnetic powder of 60-95 wt.% and thermosetting resin of 5-40 wt.% is coated with a wiring conductor 2 where metal powder is combined with thermosetting resin. The ferromagnetic powder in the insulating base body 1 absorbs unwanted radiation from the wiring conductor 2 for suppressed harmonics noise, thus a mounted semiconductor element is driven normally and stably at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board used for a semiconductor device housing package for housing a semiconductor element, a hybrid integrated circuit board, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a wiring board, for example, a wiring board used for a package for housing a semiconductor element for housing a semiconductor element is made of ceramics such as an aluminum oxide sintered body, and a semiconductor element is mounted on an upper surface thereof. And a wiring conductor made of a refractory metal metallization such as tungsten or molybdenum led out from the mounting portion or the vicinity of the mounting portion to the lower surface of the insulating substrate on the upper surface of the insulating substrate. The semiconductor element is mounted on the portion, and each electrode of the semiconductor element is electrically connected to a wiring conductor led out to the upper surface of the insulating base via an electrical connection means such as a solder bump or a bonding wire. A cover made of metal, ceramics, or the like is covered on the top surface of the semiconductor device with a sealing material such as glass, resin, brazing material, etc. It engaged, the semiconductor device as a product by housing the semiconductor element hermetically. Then, by connecting the portion of the wiring conductor extending to the lower surface of the insulating base to the wiring conductor of the external electric circuit board, each electrode of the semiconductor element is electrically connected to the external electric circuit board.

[0003] This conventional wiring board is manufactured by a ceramic green sheet laminating method. Specifically, an appropriate organic binder or solvent is added to a ceramic raw material powder such as aluminum oxide, silicon oxide, magnesium oxide or calcium oxide. A plurality of ceramic green sheets are obtained by mixing and forming a slurry into a sheet shape by employing a well-known doctor blade method, and thereafter, these ceramic green sheets are subjected to an appropriate punching process. A metal paste to be a wiring conductor is printed and applied in a predetermined pattern, and finally, these ceramic green sheets are stacked up and down in a predetermined order to form a green ceramic molded body and fired at a high temperature of about 1600 ° C. in a reducing atmosphere. Produced by

However, in the conventional wiring board, since ceramics such as an aluminum oxide sintered body constituting the insulating base have a hard and brittle property, the wiring boards are not connected to each other in a transfer process or an automatic line for manufacturing semiconductor devices. If the wiring board and a part of the automatic semiconductor device manufacturing line collide violently, the insulating substrate may be chipped, cracked, cracked, etc., and as a result, the semiconductor element cannot be housed in a gas-tight manner, and the length of the semiconductor element cannot be increased. There was a disadvantage that normal and stable operation could not be achieved over a period of time.

Further, according to this conventional method for manufacturing a wiring board, when the green ceramic molded body is fired, uneven firing shrinkage occurs in the green ceramic molded body, and the resulting wiring board has deformation such as warpage. Dimensional variations occur, and as a result,
There is a disadvantage that it is difficult to electrically and accurately connect the semiconductor element and the wiring conductor with each other.

Therefore, the insulating substrate of the wiring substrate is formed by laminating an insulating substrate made of a material obtained by bonding inorganic insulating powder with a thermosetting resin in place of conventional ceramics, and the wiring conductor is made of conventional tungsten or tungsten. There has been proposed a wiring board formed of a material obtained by bonding a metal powder such as copper with a thermosetting resin in place of a metal having a high melting point such as molybdenum.

A wiring board composed of an insulating base obtained by laminating an insulating substrate formed by bonding the inorganic insulating powder with a thermosetting resin and a wiring conductor formed by bonding a metal powder with a thermosetting resin is a thermosetting resin. A plurality of semi-cured precursor sheets prepared by mixing a resin precursor and an inorganic insulating powder are prepared and subjected to an appropriate punching process, and then these precursor sheets are mixed with a thermosetting resin precursor. A metal paste mixed with a metal powder is printed and applied in a predetermined pattern. Finally, a precursor sheet on which the metal paste is printed and applied is laminated, and a temperature of about 150 to 300 ° C. and about 4 to 100 kgf /
It is manufactured by hot pressing at a pressure of cm ² and heat curing.

According to this wiring board, the inorganic insulating powder serving as the insulating substrate and the metal powder serving as the wiring conductor are bonded by a thermosetting resin having excellent toughness. Even if a part of the automatic line collides violently, the insulating substrate will never be chipped, cracked or cracked.

According to this method of manufacturing a wiring board, the wiring board is manufactured by thermosetting a precursor of a thermosetting resin contained in the insulating base and the wiring conductor. No deformation or dimensional variation occurs.

[0010]

However, recently,
Since semiconductor devices are being driven at high speed, the driving pulse for driving the semiconductor devices has a high frequency and the rise time of the pulses has become extremely short. Higher-order harmonic noise than drive pulses is more likely to be generated in the power supply and signal of the element.

[0011] Such high-order harmonic noise propagates through a wiring conductor of a wiring board on which a semiconductor element is mounted to an external electric circuit board to which the wiring board is connected, and adversely affects other semiconductor devices. There was a problem. Another problem is that harmonic noise generated by another semiconductor device is propagated through a wiring conductor to a semiconductor element mounted on a wiring board, causing a malfunction in the semiconductor element.

On the other hand, in order to cope with high-speed driving of a semiconductor element, a material having a small loss (tan δ) is required for a material of an insulating base of a wiring board, and the above inorganic insulating powder is bonded with a thermosetting resin. There is a similar demand for a wiring board composed of an insulating substrate formed by the above and a wiring conductor formed by bonding metal powder with a thermosetting resin, but on the other hand, the loss (tan δ) of the material of the insulating base is small. In such a case, there is a problem that unnecessary radiation from the wiring conductor formed in the insulating substrate or on the surface thereof becomes large and the above-mentioned harmonic noise is easily generated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wiring conductor in which metal powder is bonded with a thermosetting resin to an insulating base in which inorganic insulating powder is bonded with a thermosetting resin. In the wiring board, the unnecessary radiation from the wiring conductor is suppressed, the harmonic noise is effectively removed, the noise is hardly emitted to the external electric circuit board, and the semiconductor element mounted is normal. Another object of the present invention is to provide a wiring board that can be driven stably at high speed.

Another object of the present invention is to provide a method of manufacturing a wiring board, comprising: attaching an insulating substrate in which inorganic insulating powder is bonded with a thermosetting resin to a wiring conductor in which metal powder is bonded with a thermosetting resin. Suppresses unnecessary radiation from wiring conductors, effectively eliminates harmonic noise, makes it difficult to emit noise to external electric circuit boards, and enables normal and stable high-speed driving of mounted semiconductor elements. An object of the present invention is to provide a manufacturing method capable of obtaining a wiring board.

[0015]

According to the present invention, there is provided a wiring board comprising:
5 to 95% by weight of inorganic insulating powder and ferromagnetic powder
A wiring conductor formed by bonding a metal powder with a thermosetting resin to an insulating substrate bonded by a thermosetting resin of about 40% by weight.

The wiring board according to the present invention is characterized in that, in the wiring board having the above structure, the ferromagnetic powder is contained in an amount of 30 to 60% by weight based on the total amount of the inorganic insulating powder. Things.

Further, the method for manufacturing a wiring board according to the present invention comprises:
5 to 95% by weight of inorganic insulating powder and ferromagnetic powder
Semi-curing of a precursor sheet obtained by mixing a thermosetting resin precursor of about 40% by weight, a predetermined punching process on the semi-cured precursor sheet, Printing a metal paste formed by mixing a metal powder and a thermosetting resin precursor on a body sheet in a predetermined pattern; and thermally curing the precursor sheet and the metal paste to form an inorganic insulating powder and a ferromagnetic material. Applying a wiring conductor in which the metal powder is bonded with the thermosetting resin to the insulating base in which the powder is bonded with the thermosetting resin.

According to the wiring board of the present invention, since the insulating base is formed by bonding the inorganic insulating powder and the ferromagnetic powder with the thermosetting resin, unnecessary radiation from the wiring conductor is prevented by the ferromagnetic powder. It can absorb and effectively remove harmonic noise, suppress noise emission to the external electric circuit board and noise propagation from the external electric circuit board, and use inorganic insulating powder to insulate the insulating substrate. Can be set to a desired small value, and a semiconductor element mounted can be normally and stably driven at high speed.

Further, according to the method of manufacturing a wiring board of the present invention, the wiring board having the above structure is formed using a precursor sheet obtained by mixing an inorganic insulating powder, a ferromagnetic powder and a thermosetting resin precursor. By manufacturing, it is possible to provide a wiring board having excellent electric characteristics, which can normally and stably drive a mounted semiconductor element at high speed.

[0020]

Next, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment in which the wiring board of the present invention is applied to a package for housing a semiconductor element for housing a semiconductor element, wherein 1 is an insulating base, and 2 is a wiring conductor.

The insulating base 1 comprises three insulating substrates 1a and 1b.
1c is formed by laminating, a concave portion 1d for accommodating the semiconductor element is provided at the center of the upper surface, and the semiconductor element 3 is bonded and fixed to the bottom surface of the concave portion 1d via an adhesive such as a resin. You.

The insulating substrates 1a and 1b constituting the insulating base 1
1c is an inorganic insulating powder, for example, silicon oxide, aluminum oxide, aluminum nitride, silicon carbide, barium titanate, strontium titanate, calcium titanate.
Titanium oxide, zeolite, etc., and ferromagnetic powders, for example, powders of ferromagnetic substances such as iron, nickel, cobalt, chromium oxide or alloys thereof, or Mn-Zn ferrites, Ni-Zn ferrites, which are ferrimagnetic substances Ba ferrite / Mg-Mn ferrite / Ni-C
Various ferrites such as u-ferrite (MOFe ₂ O ₃ :
M is a divalent metal ion) powder formed by bonding with a thermosetting resin such as an epoxy resin, a polyimide resin, a phenol resin, a thermosetting polyphenylene ether resin, a polyimide amide resin, and a bismaleimide triazine resin. .

Three insulating substrates 1a constituting the insulating base 1
1b and 1c are each formed by bonding an inorganic insulating powder and a ferromagnetic powder with a thermosetting resin such as an epoxy resin having excellent toughness, so that the insulating substrate 1 has extremely strong toughness. Thus, even if an external force is applied to the insulating substrate 1, it is possible to extremely effectively prevent the insulating substrate 1 from being chipped, cracked, or cracked by the external force.

The insulating substrate 1 made of the inorganic insulating powder, the ferromagnetic powder, and the thermosetting resin constitutes the insulating substrate 1.
The insulating substrates 1a, 1b, and 1c have a content of the inorganic insulating powder and the ferromagnetic powder of 60% by weight in the composition ratio of the inorganic insulating powder and the ferromagnetic powder to the thermosetting resin. %, The coefficient of thermal expansion of the insulating substrate 1 greatly differs from the coefficient of thermal expansion of the semiconductor element 3, the semiconductor element 3 generates heat during operation, and the heat is applied to both the semiconductor element 3 and the insulating substrate 1. As a result, a large thermal stress is generated between the two due to the difference in the thermal expansion coefficient between the two, and the large thermal stress causes the semiconductor element 3 to peel off from the insulating base 1 or cause the semiconductor element 3 to crack or chip. Tends to be easy. In addition, the content of the inorganic insulating powder and the ferromagnetic powder is
If it exceeds 95% by weight, it tends to be difficult to firmly bond the inorganic insulating powder and the ferromagnetic powder with a thermosetting resin. Therefore, the insulating substrates 1a
1b and 1c indicate that the amounts of the inorganic insulating powder and the ferromagnetic powder are in the range of 60 to 95% by weight in the composition ratio of the inorganic insulating powder and the ferromagnetic powder to the thermosetting resin. Is done.

As for the amount of the ferromagnetic powder relative to the total amount of the inorganic insulating powder and the ferromagnetic powder, when the content of the ferromagnetic powder is less than 30% by weight, unnecessary radiation from the wiring conductor 2 is reduced. The effect of absorbing and effectively removing harmonic noise tends to be small. On the other hand, if it exceeds 60% by weight, each of the insulating substrates 1a, 1b and 1c constituting the insulating base 1
, That is, a precursor sheet obtained by mixing an inorganic insulating powder and a ferromagnetic powder with a thermosetting resin precursor tends to have low strength, which tends to make handling in production difficult. Therefore, the content of the ferromagnetic powder is 30 to 60% by weight based on the total amount of the inorganic insulating powder and the ferromagnetic powder.
It is desirable to be within the range.

The particle size of the inorganic insulating powder is 1
If it is less than μm, the specific surface area of the inorganic insulating powder becomes large, so that the viscosity becomes high when forming the precursor sheet, and it tends to be difficult to form the precursor sheet stably. On the other hand, if it exceeds 50 μm, the surface roughness of the precursor sheet becomes rough, and it tends to be difficult to form a uniform wiring conductor on the surface by printing a metal paste. Therefore, the particle diameter of the inorganic insulating powder is preferably in the range of 1 to 50 μm.

The particle diameter of the ferromagnetic powder is 0.5
When the particle size is less than μm, the specific surface area of the ferromagnetic powder becomes large. Therefore, when a predetermined amount is filled, the viscosity becomes high when forming the precursor sheet, and it tends to be difficult to form the precursor sheet stably. On the other hand, if it exceeds 50 μm, the surface roughness of the precursor sheet becomes rough, and it tends to be difficult to form a uniform wiring conductor on the surface by printing a metal paste. Therefore, the particle size of the ferromagnetic powder is preferably in the range of 0.5 to 50 μm.

Further, regarding the relationship between the particle size of the ferromagnetic powder and the particle size and shape of the inorganic insulating powder, the effect of the ferromagnetic powder can be more efficiently dispersed by uniformly dispersing the ferromagnetic powder. The particle diameter of the ferromagnetic material powder is set to 1/2 or less of the particle diameter of the inorganic insulating powder, and the shape of the ferromagnetic powder is set to be spherical or polyhedral having an aspect ratio of 2 or less. Is preferred.

As described above, since the insulating base 1 has a predetermined amount of ferromagnetic powder, the ferromagnetic powder converts unnecessary radiation into heat energy and absorbs it, and has a high magnetic permeability, so that the loss (tan δ) Becomes large, and becomes high impedance with respect to harmonic noise. Therefore, unnecessary radiation is generated from input / output signals propagating through the wiring conductor 2, or an output signal containing harmonic noise is transmitted from the semiconductor element 3 mounted on the wiring board to the external electric circuit board via the wiring conductor 2. Or the input signal containing the harmonic noise from the external electric circuit board is transmitted to the semiconductor element 3 via the wiring conductor 2, the unnecessary radiation and the harmonic noise contained in the input / output signal are ferromagnetic. It will be absorbed and removed by body powder, as a result, unnecessary radiation will occur as noise,
Harmonic noise is transmitted from the semiconductor element 3 to the external electric circuit board,
Alternatively, it is not transmitted to the semiconductor element 3 from the external electric circuit board.

The ferromagnetic powder is applied to the three insulating substrates 1a, 1b, and 1c constituting the insulating base 1 in a portion where unnecessary radiation from the wiring conductor 2 and generation of harmonic noise are particularly problematic. In particular, it may be mainly contained. As a result, it is possible to effectively absorb unnecessary radiation and suppress harmonic noise by the ferromagnetic powder at that part, and to exhibit high electrical insulation and good high-frequency signal transmission characteristics at other parts. Thus, a wiring board having excellent electric characteristics as a whole can be obtained.

The insulating substrate 1 has a wiring conductor formed by bonding metal powder such as copper coated with copper, silver, gold, or silver or an alloy thereof with a thermosetting resin such as an epoxy resin from the periphery to the lower surface of the concave portion 1d. 2 are attached and formed.

The wiring conductor 2 functions to electrically connect each electrode of the semiconductor element 3 to an external electric circuit.
Each electrode of the semiconductor element 3 is electrically connected to a portion located around the concave portion 1 d through a bonding wire 4.
The portion led out to the lower surface of the insulating base 1 is electrically connected to an external electric circuit.

When the content of the metal powder contained in the wiring conductor 2 is less than 70% by weight, the electrical resistance of the wiring conductor 2 becomes high. There is a tendency that it is difficult to form a predetermined wiring conductor 2 by firmly bonding with a resin. Therefore, it is preferable that the amount of the metal powder contained in the wiring conductor 2 be in the range of 70 to 95% by weight.

The wiring conductor 2 is preferably coated with a metal having excellent corrosion resistance and good conductivity, such as nickel or gold, to a thickness of 1.0 to 20.0 μm by plating on the exposed surface. In addition, the oxidative corrosion of the wiring conductor 2 can be effectively prevented, and the wiring conductor 2 and the bonding wire 4 can be firmly electrically connected.

Thus, according to the wiring board of the present invention, the semiconductor element 3 is bonded and fixed to the bottom surface of the concave portion 1 d of the insulating base 1 with an adhesive such as a resin, and each electrode of the semiconductor element 3 is bonded via the bonding wire 4. It is electrically connected to the wiring conductor 2, and finally, the lid 5 is joined to the upper surface of the insulating base 1 via a sealing material made of resin or the like. The semiconductor device as a product is completed by housing 3 in an airtight manner.

Next, a method of manufacturing the above-described wiring board of the present invention will be described with reference to FIG.

FIGS. 2A to 2C are cross-sectional views for explaining the method of manufacturing a wiring board according to the present invention.

First, as shown in FIG.
Precursor sheets to become the insulating substrates 1a, 1b, and 1c of FIG.
Prepare 11a, 11b and 11c.

The precursor sheets 11a, 11b and 11c are 60 to 95
5% by weight of the above-mentioned inorganic insulating powder and the above-described ferromagnetic or ferrimagnetic ferromagnetic powder.
It is formed by bonding with the above-mentioned thermosetting resin precursor by weight.

These precursor sheets 11a, 11b, 11c are:
Precursor sheets 11a, 11b, etc. are used when performing fine punching or printing and applying a metal paste to be the wiring conductor 2.
Punching and printing of metal paste can be performed accurately and reliably without causing deformation or cracks in 11c.

These precursor sheets 11a, 11b, 11c
Are, for example, a silicon oxide powder having a particle size of 1 to 50 μm, a ferrite powder having a particle size of 0.5 to 20 μm, and bisphenol A
Thermosetting resin such as epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, glycidyl ester type epoxy resin and curing agent such as amine type curing agent, imidazole type curing agent, acid anhydride type curing agent The paste thus obtained is formed into a sheet by employing a sheet forming method such as a doctor blade method and is semi-cured at a temperature of about 25 to 130 ° C.

Next, as shown in FIG. 2 (b), two precursor sheets 11a, 11b, 11c of the semi-cured three precursor sheets 11a, 11b have openings A, A 'forming recesses 1d in two precursor sheets 11a, 11b. To
Through holes B and B 'are formed in the two precursor sheets 11b and 11c to route the wiring conductor 2 respectively.

The openings A and A 'and the through holes B and B' are formed by subjecting the precursor sheets 11a, 11b and 11c to a punching process which is a conventionally known punching process.
It is formed by drilling a hole of a predetermined shape in each of 11b and 11c.

In this case, the precursor sheets 11a, 11b, 11c
Since has a suitable flexibility, cracks and cracks do not occur due to fine punching.

Next, as shown in FIG. 2C, the upper and lower surfaces of the semi-cured precursor sheets 11b and 11c and the through holes B and
A metal paste 12 to be the wiring conductor 2 is printed and applied in a predetermined pattern in B ′ by using a conventionally known screen printing method and filling method.

The metal paste 12 serving as the wiring conductor 2 is, for example, a metal powder such as copper having a particle size of about 0.1 to 20 μm or a thermosetting resin such as a bisphenol A type epoxy resin, a novolak type epoxy resin, a glycidyl ester type epoxy resin. A paste obtained by adding and mixing a resin precursor and a curing agent such as an amine curing agent, an imidazole curing agent, and an acid anhydride curing agent is used.

Finally, the precursor sheets 11a, 11b, 11
c is laminated on top and bottom and heated at a temperature of about 80 to 300 ° C. for about 10 seconds to 24 hours to form precursor sheets 11a, 11b, 11
By sufficiently thermosetting the metal paste 12 printed and applied in a predetermined pattern on the precursor sheet 11b and the precursor sheets 11b and 11c, a wiring board having the wiring conductor 2 adhered to the insulating base 1 as shown in FIG. 1 is obtained. Can be

In this case, the precursor sheets 11a, 11b,
11c and the metal paste 12 hardly shrink during thermosetting, and therefore, there is no deformation or dimensional variation in the obtained wiring board, and the semiconductor element and the wiring conductor must be accurately connected. Becomes possible.

Further, since the precursor sheets 11a, 11b and 11c hardly shrink during thermosetting, even if the ferromagnetic powder is contained together with the inorganic insulating powder, the insulating substrates 1a, 1b and 1c can be used. There is no adverse effect such as warpage or deformation.

The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the case where the wiring board of the present invention is applied to a semiconductor element housing package for housing a semiconductor element has been described as an example. However, for example, wiring used for other purposes such as a hybrid integrated circuit is described. The present invention may be applied to a substrate, or a semiconductor element may be mounted by a so-called flip-chip mounting method using a pump electrode for electrical connection between the semiconductor element and a wiring conductor.

In the above embodiment, the wiring board is manufactured by laminating three precursor sheets.
A wiring board may be manufactured using one, two, or four or more precursor sheets.

Further, in the above-described embodiment, the insulating base is made of the inorganic insulating powder and the thermosetting resin. However, the insulating base is further made of glass fiber, carbon fiber, aramid fiber, alumina fiber, potassium titanate whisker, Short fibers such as aluminum borate whiskers may be blended.

Further, in the above-described embodiment, the wiring conductor is formed by bonding the metal powder with a thermosetting resin. May be formed by combining.

In this case, a low-melting-point metal powder such as tin-lead solder is blended as a low-melting-point metal into a metal paste serving as a wiring conductor, and this is printed and applied to a precursor sheet serving as an insulating base. Is applied to melt the low-melting-point metal powder, and the molten low-melting-point metal is combined with the metal powder.

[0055]

According to the wiring board of the present invention, since the insulating base is formed by bonding the inorganic insulating powder and the ferromagnetic powder with the thermosetting resin, the semiconductor element having the coefficient of thermal expansion is mounted. The ferromagnetic powder can absorb unnecessary radiation from the wiring conductors and effectively remove harmonic noise, releasing noise to the external electric circuit board and generating noise from the external electric circuit board. Noise propagation can be suppressed, and the dielectric constant of the insulating base can be set to a desired small value by the inorganic insulating powder, so that the mounted semiconductor element can be normally and stably driven at high speed. It becomes a wiring board which can be used.

Further, according to the wiring board of the present invention, the insulating base is made of the inorganic insulating powder and the ferromagnetic powder and the thermosetting resin, and the inorganic insulating powder and the ferromagnetic powder are converted into a thermosetting resin having excellent toughness. Due to the bonding with the resin, the toughness of the insulating substrate becomes extremely strong, and even if the wiring substrates or the wiring substrate and a part of the semiconductor device collide violently, the insulating substrate may be chipped, cracked, or cracked. This can be prevented very effectively.

As described above, according to the present invention, the unnecessary radiation from the wiring conductor is suppressed, the harmonic noise is effectively removed, and the semiconductor element which is hard to emit the noise to the external electric circuit board and is mounted. Can be provided normally and stably at a high speed.

According to the method of manufacturing a wiring board of the present invention, a precursor sheet and a thermosetting resin precursor obtained by mixing an inorganic insulating powder and a ferromagnetic powder with a thermosetting resin precursor are provided. The precursor sheet and the metal paste are manufactured by thermosetting a metal paste formed by mixing a metal powder, and since the precursor sheet and the metal paste hardly shrink, deformation and dimensional variation due to shrinkage do not occur. Electrical connection can be made accurately to the wiring conductor.

As a result, according to the present invention, unnecessary radiation from the wiring conductor is suppressed, and harmonic noise is effectively removed.
It is possible to provide a manufacturing method capable of obtaining a wiring board which is less likely to emit noise to an external electric circuit board and which can normally and stably drive a semiconductor element mounted at a high speed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment in which a wiring board of the present invention is applied to a package for housing a semiconductor element.

FIGS. 2A to 2C are cross-sectional views for explaining a method of manufacturing a wiring board according to the present invention.

[Explanation of symbols]

 1. Insulating base 1a, 1b, 1c ... Insulating substrate 2 ... Wiring conductors 11a, 11b, 11c ...・ ・ Precursor sheet 12 ・ ・ ・ ・ Metal paste

Claims (3)

[Claims] 1. A wiring conductor in which a metal powder is bonded by a thermosetting resin to an insulating base in which 60 to 95% by weight of an inorganic insulating powder and a ferromagnetic powder are bonded by a 5 to 40% by weight of a thermosetting resin. A wiring board characterized by being adhered. 2. The wiring board according to claim 1, wherein said ferromagnetic powder is contained in an amount of 30 to 60% by weight based on the total amount of said ferromagnetic powder and said inorganic insulating powder. 3. a step of semi-curing a precursor sheet obtained by mixing 60 to 95% by weight of an inorganic insulating powder and a ferromagnetic powder with 5 to 40% by weight of a thermosetting resin precursor; A step of performing a predetermined punching process on the semi-cured precursor sheet, and a step of printing a metal paste formed by mixing a metal powder and a thermosetting resin precursor on the punched precursor sheet in a predetermined pattern; The precursor sheet and the metal paste are thermoset, and a wiring conductor in which the metal powder is bonded with the thermosetting resin is adhered to the insulating substrate in which the inorganic insulating powder and the ferromagnetic powder are bonded with the thermosetting resin. And a method of manufacturing a wiring board.