JP2003060359A - Multilayer circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer circuit board of compactness, high performance and a low price, which can make a high-frequency circuit and a low-frequency circuit coexist in compactness, and has low loss and heat resistance in a high-frequency circuit board, and where a pattern is not too fine and high density mounting is possible. SOLUTION: The multilayer circuit board has a high-frequency resin board 10 where a ground conductor 11 is disposed closely in one surface and a low-frequency resin board 20, where a ground conductor 21 is disposed closely in the other surface. The high-frequency resin board 10 and the low-frequency resin board 20 are opposed at a ground conductor side. At least a part of a conductor pattern 12 formed in the high-frequency resin board 10 and a part of a conductor pattern 22 formed in the low-frequency resin board 20 are connected via a through-hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer circuit board in which a high frequency circuit board used in a high frequency band, particularly a millimeter wave band, and a low frequency circuit board such as a power supply circuit are combined.

[0002]

2. Description of the Related Art In recent years, with the rapid increase in communication information, there has been a strong demand for downsizing, weight saving, and speeding up of communication devices, and a low dielectric electrical insulating material that can meet these demands has been required. Especially mobile communication such as car phones and digital mobile phones,
The frequency band of radio waves used in the radar system is a high frequency band in the so-called millimeter wave band (about 30 to 300 GHz). Along with the rapid development of communication equipment used for these communication and radar systems, miniaturization and high-density mounting of housings, substrates, and electronic elements are being pursued. In order to reduce the size and weight of communication equipment compatible with high-frequency regions such as the gigahertz band, it is necessary to develop an electrically insulating material as a substrate material that has both excellent high-frequency transmission characteristics and appropriate low-dielectric characteristics. is necessary.

That is, in the circuit formed on the substrate, energy loss in the transmission process called dielectric loss occurs. This energy loss is not preferable because it is consumed as heat energy in the circuit and is released as heat. This energy loss is caused by a change in the electric field of the dipole caused by dielectric polarization in the low frequency region, and is caused by ionic polarization or electronic polarization in the high frequency region. The ratio of the energy consumed in the dielectric per cycle of the alternating electric field and the energy stored in the dielectric is called the dielectric loss tangent and is represented by tan δ. Therefore, tan δ increases as the frequency increases in the high frequency region. In addition, since the amount of heat generated per unit area increases due to high-density mounting of electronic elements, it is necessary to use a material having a small tan δ in order to reduce the dielectric loss of the insulating material as much as possible. The use of low-dielectric polymer materials with low dielectric loss suppresses dielectric loss, resulting in less signal malfunctions. Therefore, materials with low transmission loss (energy loss) are strongly desired in the high-frequency communication field. ing.

Further, in the case of a substrate used at a high frequency such as a millimeter wave band, when a line is formed with a substrate having a high dielectric constant, the line width becomes narrow, and the precision of circuit pattern production becomes unnecessarily high, which is practically used. It is an upper problem. Further, the same problem occurs with a substrate having a large thickness. further,
If the thickness of the substrate is thick, the propagation modes become multimode, and it becomes difficult for signals to pass through the transmission path, resulting in extremely poor transmission efficiency.

However, when the thickness of the substrate is optimized for high frequencies, the thickness of the substrate becomes thin and it becomes difficult to maintain the strength of the substrate. Therefore, at present, the thickness of the substrate is ensured even if some kind of reinforcing material is provided or the transmission characteristics are sacrificed to some extent.

Further, as a performance further required for the low dielectric constant material having excellent dielectric properties and insulation resistance as described above, since a soldering step is necessarily included in the device forming step, heating at least at 260 ° C. for 120 seconds. Heat resistance that can withstand is required, chemical stability such as heat resistance and alkali resistance,
It must also have excellent moisture resistance and mechanical properties.

On the other hand, the high frequency circuit is rarely used alone, and is accompanied by a circuit that functions in a so-called low frequency region, such as a power supply circuit, a bias circuit, various circuits associated with a modulation signal, an IF signal circuit, and the like. There are many. Such a low frequency circuit also differs from the high frequency circuit in the characteristics required for the substrate. For this reason, the resin material used for the substrate, its thickness, and the pattern configuration are different, and it is not realistic to configure them on the same substrate. On the other hand, if the high-frequency substrate and the low-frequency substrate are separately manufactured and arranged on the same plane, a considerable area is occupied, and downsizing becomes difficult.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to allow a high-frequency circuit and a low-frequency circuit to coexist more compactly, have a low loss in a high-frequency circuit board, have heat resistance, and have a fine pattern. It is an object of the present invention to provide a small-sized, high-performance, and low-priced multilayer circuit board that can be mounted in high density without becoming too high.

[0009]

These objects are achieved by the present invention described in (1) to (7) below. (1) At least a high-frequency resin substrate having a ground conductor closely disposed on one surface and a low-frequency resin substrate having a ground conductor closely disposed on one surface, and the high-frequency resin substrate The low frequency resin substrate is arranged to face each other on the ground conductor side, and at least a part of the conductor pattern formed on the high frequency resin substrate and a part of the conductor pattern formed on the low frequency resin substrate. A multilayer circuit board in which and are connected by through holes. (2) The multilayer circuit board according to (1), wherein the high-frequency resin board has a thickness of 0.5 mm or less. (3) The multilayer circuit board according to (1) or (2) above, wherein the high frequency resin substrate is used in a frequency band of 30 GHz or higher and the low frequency resin substrate is used in a frequency of 500 MHz or lower. (4) Furthermore, the said high frequency circuit board is a multilayer circuit board in any one of said (1)-(3) covered with the shield material. (5) The above-mentioned (1) to (4), in which at least one of the electronic component mounting portions of the high-frequency resin substrate has a mounting hole penetrating to the ground conductor, and the electronic component is housed in the mounting hole. One of the multilayer circuit boards. (6) The high-frequency circuit board according to (5), wherein the conductor line of the high-frequency circuit board and the connection terminal of the electronic component are substantially on the same plane. (7) The high-frequency resin substrate is a resin composition composed of one or more resins having a weight average absolute molecular weight of 1000 or more, and the total number of carbon atoms and hydrogen atoms in the composition is 99. % Or more and a part or all of the resin molecules are formed of a heat resistant low dielectric polymer material having a chemical bond with each other, the multilayer circuit board according to any one of (1) to (6) above. .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The multilayer circuit board of the present invention has at least a high-frequency resin substrate in which a ground conductor is closely arranged on one surface, and a low-frequency resin substrate in which a ground conductor is closely arranged on one surface, The high-frequency resin substrate and the low-frequency resin substrate are arranged so as to face each other on the ground conductor side, and are formed on at least a part of the conductor pattern formed on the high-frequency resin substrate and the low-frequency resin substrate. A part of the conductor pattern is connected by a through hole.

By stacking the high-frequency substrate and the low-frequency substrate in this manner, the high-frequency circuit and the low-frequency circuit associated therewith can be housed in a more compact space, which is small and thin. The high frequency device can be provided. In addition, the low-frequency circuit board can supplement the board strength that is a problem when the thickness of the high-frequency board is optimized.
In particular, there is no need to provide a reinforcing material.

Next, the multilayer circuit board of the present invention will be described in more detail with reference to the drawings. FIG. 1 is an exploded perspective view showing a configuration example of a multilayer circuit board according to the present invention, FIG. 2 is a sectional view, and FIGS. 1 and 2 show different configuration modes.

1 and 2, the multilayer circuit board of the present invention has a high-frequency resin substrate 10 on one side of which a ground conductor 11 is closely arranged, and a ground conductor 21 on one side of the same. It has a low frequency resin substrate 20. Ground conductor 1 of high frequency resin substrate 10 and low frequency resin substrate 20
The conductor lines 12 and
22 is formed and constitutes a desired circuit.

The high-frequency resin substrate 10 and the low-frequency resin substrate 20 are opposed to each other on the side where the ground conductors 11 and 21 are arranged, and are preferably adhered and fixed by an adhesive layer 31. .

Further, each conductor line 12 and 22, the ground conductor 1
1, 21 are connected by a through hole 32 as needed so that a necessary circuit can be configured. In this case, the conductor line 11 of the high frequency resin substrate 10 and the conductor line 21 of the low frequency resin substrate 20 are at least 1
The through holes 32 are connected at more than one place so that they are electrically connected at at least one place.

The high frequency resin substrate of the present invention can be preferably used in a millimeter wave band of a frequency band of 30 to 300 GHz. Above all, it is preferable to use in the frequency band of 30 to 110 GHz, particularly in the range of 59 to 60 GHz or 76 to 77 GHz in consideration of use as a radar.

On the other hand, the low frequency resin substrate of the present invention is not particularly limited as long as it has a lower frequency than the above high frequency resin substrate, but is preferably 500 MHz or less, particularly 2
The frequency is preferably 00 MHz or less, more preferably 100 MHz or less, and the lower limit is DC.

A ground conductor is closely attached and arranged on one surface of the high frequency resin substrate. This ground conductor surface is usually
The ground pattern of the metal foil is formed so as to cover almost the entire area. A conductor line is formed on the other surface. The surface on which the conductor line is formed is usually the circuit formation surface, and the surface on the opposite side on which the ground pattern is formed is the ground surface. The ground pattern and the pattern on the circuit forming surface can mutually form a microstrip line, or can form a capacitor, an inductor, or the like.

Further, a ground conductor is closely attached to and disposed on one surface of the low frequency resin substrate as in the case of the high frequency resin substrate. In this case, the ground conductor mainly functions as GND in the low frequency circuit.

The ground pattern also serves as a shield between the high frequency circuit formed on the high frequency resin substrate and the low frequency circuit formed on the low frequency resin substrate. By stacking the ground conductor surfaces of the high-frequency resin substrate and the low-frequency resin substrate so as to face each other, interference between the two can be eliminated and good operation in each frequency band can be maintained.

The conductor line formed on the high-frequency resin substrate and the circuit constituted by the circuit parts associated with the conductor line are, for example, a millimeter-wave band system, which processes a millimeter-wave band radio wave transmitted and received from an antenna. In the case of a radar system required for, an oscillation circuit, a frequency multiplication circuit, a mixing circuit (modulation circuit), an amplification circuit, a filtering circuit (filter circuit), a direction control circuit and the like.

Examples of the circuit constituted by the conductor line formed on the low frequency resin substrate and the circuit components associated therewith include, for example, a power supply circuit, a bias circuit, various circuits associated with a modulation signal, and an IF signal. Examples of the circuit include circuits necessary for the high-frequency circuit to function.
By arranging these circuits in close contact with the high frequency circuit, the size of the entire device can be made more compact.

As the material of the conductor line and the ground conductor formed on the substrate, simple metals such as gold, silver, copper, nickel, chromium, titanium and aluminum, or alloys using these can be used. These are usually adhered and fused on the substrate as a metal conductor film, but they can also be formed by a vapor deposition method such as vapor deposition, a sputtering method, or a wet plating method. The formed metal conductor layer can be etched (wet or dry) into a desired pattern to obtain a circuit pattern. As the bonding pad on the conductor line side, a material similar to the above-mentioned conductor line material may be used, or a material having a good contact attribute with the bonding wire may be used.

The thickness of the conductor line formed on the substrate is usually about 10 to 1000 μm, but it is preferably 70 μm or less, particularly 35 μm or less, further preferably 18 μm or less in the millimeter wave band. The lower limit is about 3 times the skin depth of the frequency used.

The thickness of the substrate depends on the circuit to be formed and the frequency band used, but in the case of a high frequency resin substrate, it is preferably 0.05 to 0.5 mm, more preferably 0.05 to 0. It is 15 mm, especially about 0.075 to 0.15 mm. The low frequency resin substrate is not particularly limited and may be set to an optimum thickness depending on the required strength, shape, material, etc., but it is particularly preferably 0.4 mm or less.

In the present invention, it is preferable that the high frequency circuit board cover the upper space of the board with a shield member as shown in FIG. 3 so that the circuit mounted on the board is electromagnetically shielded from the outside. Good. In addition, the shield member 40
Is preferably connected to the conductor pattern 12 on the substrate and further connected to the ground conductor 22 through the through hole 32. In this way, by connecting the shield member 40 and the ground conductor 22 with the through holes 32, it is possible to perform more complete shielding and almost eliminate the electromagnetic influence from the external environment.

The shield member is not particularly limited as long as it has conductivity and is relatively easy to process.
Specifically, aluminum, brass, stainless steel (SUS303, 304, etc.), metallized resin, ceramics, etc. can be used.

If the height of the shield member is too high, the device becomes too large, and if it is too low, it interferes with the circuit components. Therefore, depending on the components used, it is preferable that the distance from the substrate surface is 5 mm or less, particularly about 0.5 to 1 mm.

In the present invention, at least one of the electronic component mounting portions of the high frequency resin substrate is preferably provided with a mounting hole 1a penetrating to the ground conductor metal surface. By forming such a mounting hole and housing and wiring the electronic component in the mounting hole, the electronic component and the conductor line can be connected in a state in which the vertical and horizontal positions are closer to each other.

As described above, the mounting hole is provided in the electronic component mounting portion of the substrate, and the electronic component is arranged inside the mounting hole, so that the conductor line on the surface of the substrate and the connection terminal for the electronic component are substantially in the plane position. Can be connected in a state close to
The vertical separation distance and horizontal separation distance of the bonding wire that connects the conductor line and the electronic component can be greatly reduced, and the characteristic impedance at the connection portion is greatly reduced, and the transmission characteristics are greatly improved. can do.

Further, since the high-frequency resin substrate of the present invention uses the following heat-resistant low-dielectric polymer material, it has a low relative permittivity and low dielectric loss tangent, is thermally stable and has high heat resistance. In addition, the heat shrinkage rate is low, manufacturing and processing are easy, high-density mounting and multi-layering are possible, and a high-performance high-frequency circuit board can be obtained.

This mounting hole forms a recess in the substrate,
The form of the hole is not particularly limited as long as it is a hole in which electronic parts can be stored, but it is preferable that the hole penetrates to the ground conductor. By penetrating the mounting hole to the ground conductor, manufacturing is facilitated, and the electronic component can be arranged on the ground conductor, and the heat dissipation effect of the ground conductor can be utilized. By using the grounding conductor for heat dissipation of the electronic component as described above, it is not necessary to attach a heat dissipation plate to the electronic component, manufacturing is facilitated, and the circuit can be made more compact.

The mounting hole is preferably as small as possible in order to reduce the distance between the conductor line of the substrate and the electronic component, and it is preferable that the mounting hole is slightly larger than the outer shape of the electronic component to be housed. Considering the ease of maintenance, the distance between the outer periphery of the electronic component and the inner periphery of the mounting hole is preferably 50 to 200 μm, particularly 50 to 200 μm.
It is preferable to set the thickness to about 100 μm.

In particular, the distance between the conductor line and the mounting terminal of the electronic component is 0.2 mm or less in terms of the average horizontal separation distance of the bonding portion, and the average vertical separation distance thereof is about 0.05 mm or less. It is preferable.

The ratio of the thickness of the circuit element to the thickness of the substrate is 0.6 or more, preferably about 0.8 to 1.2.

It is most preferable that the vertical separation distance between the conductor line and the mounting terminal of the electronic component is substantially a plane position. However, as described above, the thickness of the substrate is optimal depending on the circuit configuration and the frequency band used. Since the thickness of the electronic component is smaller than or close to the thickness of such a substrate, the range of the above relation may be set.

The electronic component housed inside the mounting hole is not particularly limited, and any electronic component that can be used in a high frequency circuit may be used. Specifically, a high frequency circuit element such as a bipolar transistor, a junction type FET (in particular, a Schottky junction type), a MOS-FET, an IC, a resistor, a capacitor, an inductor, an MMIC can be used.

These electronic components are preferably mounted on the ground conductor. The electronic components can be fixed on the ground conductor by screwing, mechanical methods using screws and fixtures, fixing with an adhesive, brazing or soldering. You may fix with. In this case, if the following heat-resistant low-dielectric polymer material is used as the substrate material, it can withstand the heat when fixing by brazing or soldering.

The electronic component and the conductor line are connected by wire bonding. Wire bonding is roughly classified into a nail bonding method and a wedge bonding method. In any case, a thin wire connects between the bonding pad formed on the semiconductor element and the bonding pad (which may be the wiring itself) formed on another component. Specifically, the two are connected to each other using solid-phase diffusion bonding of the wire and the bonding pad. However,
In order to realize this solid phase diffusion bonding, when the wire is brought into contact with the bonding pad, they are subjected to heat and / or ultrasonic waves and a load (for example, a load of 50 to 150 g).
And must be added via a tool called a capillary or wedge.

As the bonding pad, aluminum, copper or the like is usually used, and as the wire, gold, aluminum or the like is used.

The heat-resistant low-dielectric polymer material in the present invention is one or more having a weight average absolute molecular weight of 1000 or more.
A resin composition composed of at least one kind of resin, wherein the sum of the number of carbon atoms and hydrogen atoms is 99% or more, and some or all of the resin molecules are chemically bonded to each other. It is a thing. By using the resin composition having such a weight average absolute molecular weight, the strength, the adhesiveness with a metal, and the heat resistance when used as a heat resistant low dielectric polymer material become sufficient. On the other hand, the weight average absolute molecular weight is 1000
If it is smaller, mechanical properties, heat resistance, etc. become insufficient, which is not suitable. It is particularly preferably 3000 or more, and most preferably 5000 or more. The upper limit of the weight average absolute molecular weight at this time is not particularly limited, but is usually about 10 million.

In addition, the reason why the sum of carbon, hydrogen and the number of atoms in the resin composition of the present invention is 99% or more is to make the existing chemical bond a non-polar bond. Has sufficient electric characteristics when used as a conductive polymer material. On the other hand, when the total number of carbon and hydrogen atoms is less than 99%, particularly when the number of atoms forming polar molecules such as oxygen atoms and nitrogen atoms is more than 1%, electrical characteristics, especially It is not suitable because the dielectric loss tangent becomes high.

Specific examples of the resin constituting the above polymer material include low density polyethylene, ultra low density polyethylene,
Ultra ultra low density polyethylene, high density polyethylene, low molecular weight polyethylene, ultra high molecular weight polyethylene, ethylene-
Homogeneous or copolymers of non-polar α-olefins such as propylene copolymer, polypropylene, polybutene, poly-4-methylpentene [hereinafter also referred to as (co) polymer], butadiene, isoprene, pentadiene, hexadiene, heptadiene, octadiene. (Co) polymers of conjugated diene monomers such as phenylbutadiene and diphenylbutadiene, styrene, nucleus-substituted styrenes such as methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, chlorostyrene, α-substituted styrenes such as Examples thereof include (co) polymers of each monomer of carbon ring-containing vinyl such as α-methylstyrene, α-ethylstyrene, divinylbenzene, and vinylcyclohexane.

In the above, polymers of nonpolar α-olefin monomers, conjugated diene monomers, and carbocycle-containing vinyl monomers are mainly exemplified, but for example, nonpolar α-olefins are used.
Olefin monomer and conjugated diene monomer, non-polar α-
It may be a copolymer obtained from monomers of different compound species such as an olefin monomer and a carbocycle-containing vinyl monomer.

As described above, the resin composition is composed of one or more of these polymers, that is, the resins, and some or all of the resin molecules are chemically bonded to each other. There must be. Therefore, some may be in a mixed state. By having a chemical bond in at least a portion thereof, the strength, adhesiveness with metal, and heat resistance when used as a heat resistant low dielectric polymer material become sufficient. On the other hand, when it is simply mixed and does not have a chemical bond, it is insufficient from the viewpoint of heat resistance and mechanical properties.

The form of the chemical bond in the present invention is not particularly limited, and examples thereof include a crosslinked structure, a block structure and a graft structure. A known method may be used to generate such a chemical bond, and preferred embodiments of the graft structure and the block structure will be described later. As a specific method for producing a crosslinked structure, crosslinking by heat is preferable,
The temperature at this time is preferably about 50 to 300 ° C. In addition to this, crosslinking by electron beam irradiation and the like are also included.

The presence or absence of a chemical bond in the present invention can be confirmed by determining the degree of cross-linking and the graft efficiency in the graft structure. It can also be confirmed by a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Generally, one polymer segment contains approximately 10 μm of the other polymer segment.
m or less, more specifically, 0.01 to 10 μm dispersed as fine particles. On the other hand, in a simple mixture (blended polymer), compatibility between both polymers, such as a graft copolymer, is not seen, and the particle size of dispersed particles becomes large.

The resin composition of the present invention is a copolymer in which a non-polar α-olefin polymer segment and a vinyl aromatic copolymer segment are chemically bonded. A preferable example is a thermoplastic resin having a multiphase structure in which the dispersed phase formed is finely dispersed in the continuous phase formed from the other segment.

The non-polar α-olefin polymer, which is one of the segments in the thermoplastic resin having the above-mentioned specific multiphase structure, is a non-polar compound obtained by high-pressure radical polymerization, medium-low pressure ionic polymerization or the like. It must be a homopolymer of α-olefin monomers or a copolymer of two or more non-polar α-olefin monomers. A copolymer with a polar vinyl monomer is not suitable because it has a high dielectric loss tangent. As the non-polar α-olefin monomer of the polymer, ethylene, propylene, butene-1, hexene-1, octene-1,4-
Methylpentene-1 is mentioned, among them, ethylene,
Propylene, butene-1, 4-methylpentene-1,
The obtained nonpolar α-olefin polymer has a low dielectric constant, which is preferable.

Specific examples of the non-polar α-olefin (co) polymer include low density polyethylene, ultra low density polyethylene, ultra ultra low density polyethylene, high density polyethylene, low molecular weight polyethylene, ultra high molecular weight polyethylene,
Examples thereof include ethylene-propylene copolymer, polypropylene, polybutene, and poly-4-methylpentene. Further, these non-polar α-olefin (co) polymers can be used alone or in combination of two or more kinds.

The preferred molecular weight of such a non-polar α-olefin (co) polymer is 1000 in terms of weight average absolute molecular weight.
That is all. This upper limit is not particularly limited, but 1000
It is about 10,000.

On the other hand, the vinyl aromatic polymer, which is one of the segments in the thermoplastic resin exhibiting a specific multiphase structure, is a non-polar one, and specifically, styrene, nucleus-substituted styrene, For example, methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, chlorostyrene, α-substituted styrene such as α-methylstyrene, α-ethylstyrene, o-, m-, p-divinylbenzene (preferably m-, p- It is a (co) polymer of each monomer such as divinylbenzene, particularly preferably p-divinylbenzene. In this way, to make non-polar, when a monomer having a polar functional group is introduced by copolymerization,
This is because the dielectric loss tangent becomes high, which is not suitable. The vinyl aromatic polymer may be used alone or in combination of two or more kinds.

Among them, the vinyl aromatic copolymer is preferably a vinyl aromatic copolymer containing a divinylbenzene monomer in order to improve heat resistance. The vinyl aromatic copolymer containing divinylbenzene, specifically, styrene,
Nucleo-substituted styrene such as methyl styrene, dimethyl styrene, ethyl styrene, isopropyl styrene, chlorostyrene, α-substituted styrene such as α-methyl styrene, α-ethyl styrene, etc. It is a polymer.

The ratio of the divinylbenzene monomer to the other vinyl aromatic monomer as described above is not particularly limited, but in order to satisfy the solder heat resistance, the divinylbenzene monomer is used. It is preferable that the ratio is 1% by weight or more. The divinylbenzene monomer may be 100% by weight, but the upper limit is preferably 90% by weight due to problems in synthesis.

The molecular weight of the vinyl aromatic polymer, which is one of the above segments, is 10 in terms of weight average absolute molecular weight.
It is preferably 00 or more. The upper limit is not particularly limited, but is about 10 million.

The thermoplastic resin exhibiting a specific multi-phase structure in the present invention has an olefin polymer segment of 5 to 95.
%, Preferably 40 to 90% by weight, most preferably 50 to 80% by weight. Therefore, the vinyl polymer segment is 95 to 5% by weight, preferably 60 to 10% by weight, and most preferably 50 to 20% by weight.

When the olefin polymer segment is reduced, the molded product becomes brittle, which is not preferable. Further, when the amount of the olefin-based polymer segment is large, the adhesiveness to the metal is low, which is not preferable.

The weight average absolute molecular weight of such a thermoplastic resin is 1,000 or more. The upper limit is not particularly limited, but is about 10 million from the viewpoint of moldability.

Specific examples of the copolymer having a structure in which the olefin polymer segment and the vinyl polymer segment are chemically bonded include a block copolymer and a graft copolymer. Of these, graft copolymers are particularly preferred because of their ease of production. It should be noted that these copolymers may contain an olefin-based polymer or a vinyl-based polymer as long as they do not deviate from the characteristics of the block copolymer, the graft copolymer and the like.

The method for producing a thermoplastic resin exhibiting a specific multiphase structure in the present invention may be any method such as a chain transfer method or an ionizing radiation irradiation method which is generally well known as a grafting method. Most preferred is the method described below. This is because the grafting efficiency is high and secondary aggregation due to heat does not occur, so that the performance is more effectively expressed and the manufacturing method is simple.

The method for producing a graft copolymer, which is a thermoplastic resin exhibiting a specific multiphase structure, in the present invention will be described in detail below. That is, the olefin polymer 100
By suspending parts by weight in water, vinyl aromatic monomer 5 is separately added.
To 400 parts by weight, one or a mixture of two or more radically polymerizable organic peroxides represented by the following general formula (1) or (2) is added to 100 parts by weight of the vinyl monomer. 1 to 10 parts by weight and a total of 10 radical polymerization initiators having a decomposition temperature of 40 to 90 ° C. for obtaining a half-life of 10 hours are vinyl monomers and radically polymerizable organic peroxides.
A solution prepared by dissolving 0.01 to 5 parts by weight with respect to 0 parts by weight is added, and the mixture is heated under the condition that decomposition of the radical polymerization initiator does not substantially occur, vinyl monomer, radical polymerizable organic peroxide. The olefin polymer is impregnated with the compound and the radical polymerization initiator, and the temperature of this aqueous suspension is raised to copolymerize the vinyl monomer and the radically polymerizable organic peroxide in the olefin copolymer. To obtain a grafted precursor.

Next, 100 to 30 of the grafted precursor is added.
The graft copolymer of the present invention can be obtained by kneading under melting at 0 ° C. At this time, a graft copolymer can also be obtained by separately mixing an olefin polymer or a vinyl polymer with the grafting precursor and kneading them under melting. Most preferred is a graft copolymer obtained by kneading a grafting precursor.

[0063]

[Chemical 1]

In the general formula (1), R ₁ represents a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, R ₂ represents a hydrogen atom or a methyl group, and R ₃ and R ₄ respectively have 1 to 4 carbon atoms.
It indicates an alkyl group, R ₅ represents an alkyl group, a phenyl group, an alkyl-substituted phenyl group or a cycloalkyl group having 3 to 12 carbon atoms having 1 to 12 carbon atoms. m ₁ is 1 or 2
Is.

[0065]

[Chemical 2]

In the general formula (2), R ₆ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R ₇ represents a hydrogen atom or a methyl group, and R ₈ and R ₉ respectively have 1 to 4 carbon atoms.
R ₁₀ represents an alkyl group having 1 to 12 carbon atoms, a phenyl group, an alkyl-substituted phenyl group or a cycloalkyl group having 3 to 12 carbon atoms. m ₂ is 0, 1 or 2.

Specific examples of the radical-polymerizable organic peroxide represented by the general formula (1) include t-butylperoxyacryloyloxyethyl carbonate; t-amylperoxyacryloyloxyethyl carbonate. Bonate; t-hexyl peroxyacryloyloxyethyl carbonate;
1,1,3,3-Tetramethylbutylperoxyacryloyloxyethyl carbonate; cumylperoxyacryloyloxyethyl carbonate; p-isopropyl cumylperoxyacryloyloxyethyl carbonate ;
t-Butylperoxymethacryloyloxyethyl carbonate; t-Amylperoxymethacryloyloxyethyl carbonate; t-hexylperoxymethacryloyloxyethyl carbonate; 1,1,3,3- Tetramethylbutylperoxymethacryloyloxyethyl carbonate; cumylperoxymethacryloyloxyethyl carbonate; p-isopropyl cumylperoxymethacryloyloxyethyl carbonate; t-butylperoxymethacryloyloxy Ethyl carbonate-bonate; t-
Amyl peroxyacryloyloxy ethoxyethyl carr
Carbonate; t-hexylperoxyacryloyloxyethoxyethyl carbonate; 1,1,3,3-tetramethylbutylperoxyacryloyloxyethoxyethyl carbonate; cumylperoxyacryloyloxyethoxyethyl Carbonate; p-Isopropylcumylperoxyacryloyloxyethoxyethyl carbonate;
t-butylperoxymethacryloyloxyethoxyethyl carbonate; t-amylperoxymethacryloyloxyethoxyethyl carbonate; t-hexylperoxymethacryloyloxyethoxyethyl carbonate;
1,1,3,3-Tetramethylbutylperoxymethacryloyloxyethoxyethyl carbonate; cumylperoxymethacryloyloxyethoxyethyl carbonate
P-isopropylcumylperoxymethacryloyloxyethoxyethyl carbonate; t-butylperoxyacryloyloxyisopropyl carbonate; t-amylperoxyacryloyloxyisopropyl carbonate; t-hexyl Peroxyacryloyloxy isopropyl carbonate; 1,1,3,3-tetramethylbutyl peroxyacryloyloxy isopropyl carbonate; cumyl peroxyacryloyloxy isopropyl carbonate; p-isopropyl chloride Milperoxyacryloyloxy isopropyl carbonate; t-butyl peroxymethacryloyloxy isopropyl carbonate
T; amylperoxymethacryloyloxyisopropyl carbonate; t-hexylperoxymethacryloyloxyisopropyl carbonate; 1,1,3,3-
Examples thereof include tetramethylbutylperoxymethacryloyloxyisopropyl carbonate; cumylperoxymethacryloyloxyisopropyl carbonate; p-isopropylcumylperoxymethacryloyloxyisopropyl carbonate.

Further, as the compound represented by the general formula (2), t-butylperoxyallyl carbonate; t
-Amyl peroxyallyl carbonate; t-hexyl peroxyallyl carbonate; 1,1,3,3-tetramethylbutyl peroxyallyl carbonate; p-menthane peroxyallyl carbonate Cumyl peroxyallyl carbonate; t-butyl peroxy methallyl carbonate; t-amyl peroxy methallyl carbonate; t-hexyl peroxy methallyl carbonate;
1,1,3,3-Tetramethylbutylperoxymethallyl carbonate; p-menthane peroxymethallyl carbonate
Bonate; cumyl peroxymethalyl carbonate; t
-Butylperoxyallyloxyethyl carbonate; t
-Amyl peroxyallyloxyethyl carbonate; t
-Hexyl peroxyallyloxyethyl carbonate;
t-Butylperoxymetallyloxyethyl carbonate
T; t-amyl perxyl metalyloxyethyl carbonate
T-hexyl peroxymetalloxyethyl carbonyl; t-butyl peroxyallyloxy isopropyl carbonyl; t-amyl peroxyallyloxy isopropyl carbonyl; t-hexyl peroxyallyloxy isopropyl carbonyl Carbonate; t-Butylperoxymetallyloxyisopropyl carbonate; t-Amylperoxymetalloyloxyisopropyl carbonate; t-Hexylperoxymetalloyloxyisopropyl carbonate
And the like.

Of these, t-butylperoxyacryloyloxyethyl carbonate; t-butylperoxymethacryloyloxyethyl carbonate; t-butylperoxyallylcarbonyl carbonate; t-butylperoxy It is a methallyl carbonate.

The graft efficiency of the graft copolymer thus obtained is 20 to 100% by weight. Grafting efficiency is obtained by solvent extraction of ungrafted polymer,
It can be calculated from the ratio.

As the thermoplastic resin exhibiting a specific multiphase structure in the present invention, a graft copolymer of the above-mentioned non-polar α-olefin polymer segment and vinyl aromatic polymer segment is preferable. In such a graft copolymer, a nonpolar conjugated diene polymer segment may be used instead of or in addition to the nonpolar α-olefin polymer segment. As the non-polar conjugated diene polymer, those mentioned above can be used, and they may be used alone or in combination of two or more kinds.

The non-polar α-olefin polymer in the above graft copolymer may contain a conjugated diene monomer, and the non-polar conjugated diene polymer may contain α-.
An olefin monomer may be included.

The obtained graft copolymer can be further crosslinked by using divinylbenzene or the like. In particular, a graft copolymer containing no divinylbenzene monomer is preferable from the viewpoint of improving heat resistance.

On the other hand, the thermoplastic resin having a specific multiphase structure in the present invention may be a block copolymer, and the block copolymer may be a polymer of at least one vinyl aromatic monomer. And a block copolymer containing at least one polymer of a conjugated diene. Even if it is a linear type, it is a radial type, that is, a hard segment and a soft segment are bound in a radial pattern. Good. The polymer containing the conjugated diene may be a random copolymer with a small amount of a vinyl aromatic monomer, and is a so-called taper type block copolymer, that is, a vinyl aromatic monomer in one block. The body may gradually increase.

The structure of the block copolymer is not particularly limited and may be any of (AB) _n type, (AB) _n -A type and (A, B) _n -C type. . In the formula, A
Is a polymer of vinyl aromatic monomer, B is a polymer of conjugated diene, C is a coupling agent residue, and n is an integer of 1 or more. In this block copolymer, it is also possible to use a block copolymer in which the conjugated diene portion is hydrogenated.

In such a block copolymer, the above-mentioned nonpolar α-olefin-based polymer may be used instead of or in addition to the above-mentioned nonpolar conjugated diene-based copolymer. The diene polymer may contain an α-olefin monomer, and may be a non-polar α-
The olefin polymer may contain a conjugated diene monomer. The amount ratio of each segment in the block copolymer and a preferable embodiment are the same as those in the graft copolymer.

In order to improve heat resistance, the resin composition of the present invention, preferably a thermoplastic resin (particularly preferably a graft copolymer) showing a specific multiphase structure, is
It is preferable to add a non-polar α-olefin-based polymer containing a monomer of methylpentene-1. In the present invention, non-polar α-containing a monomer of 4-methylpentene-1
The olefin polymer may be contained in the resin composition without forming a chemical bond, but in such a case, its addition is not always necessary. However,
It may be further added in order to obtain desired characteristics.

4- in the non-polar α-olefin copolymer containing such a monomer of 4-methylpentene-1
The proportion of the monomer of methylpentene-1 is preferably 50% by weight or more. In addition, such a nonpolar α-olefin-based copolymer may contain a monomer of a conjugated diene.

In particular, the non-polar α-olefin copolymer containing 4-methylpentene-1 monomer is poly 4-, which is a homopolymer of 4-methylpentene-1 monomer.
It is preferably methylpentene-1.

Poly-4-methylpentene-1 is a crystalline poly-4-methylpentene-1 which has a propylene content of 2%.
Isotactic poly-4-methylpentene-1 in which 4-methylpentene-1 which is a monomer is polymerized using a Ziegler-Natta type catalyst or the like is preferable.

The ratio of poly-4-methylpentene-1 to the thermoplastic resin exhibiting a specific multiphase structure is not particularly limited,
In order to satisfy heat resistance and adhesion to metal, poly 4
The proportion of -methylpentene-1 is preferably 10 to 90% by weight. If the proportion of poly-4-methylpentene-1 is low, solder heat resistance tends to be insufficient. Also poly 4
-When the proportion of methylpentene-1 is large, the adhesion with metal tends to be insufficient. Poly-4-methylpentene-1
Instead, the addition amount of the copolymer may be in accordance with this.

The softening point of the resin composition of the present invention (including a non-polar α-olefin polymer containing a monomer of 4-methylpentene-1) is 200 to 260 ° C. By using it, sufficient solder heat resistance can be obtained.

The heat resistant low dielectric polymer material in the present invention can be obtained by a method of molding a resin material composed of the above resin composition into a desired shape such as a thin film by hot pressing or the like. In addition, shear mixers such as roll mixers, Banbury mixers, and knee mixers
It can also be obtained by a method of melt-mixing with another thermoplastic resin using a doubler, single-screw or twin-screw extruder, etc., and molding into a desired shape.

In the above, not only the resin material but also silica powder, alumina powder, and precipitated barium (BaSO ₄ ) which have been conventionally used as a reinforcing filler in rigid substrates and the like.
Low dielectric properties (low dielectric constant, low dielectric loss tangent) for controlling thermal conductivity, expansion coefficient control, adhesion of copper etc. by plating, adhesion improvement, and cost reduction
It is preferable to use it within a range that does not hurt. The reinforcing filler can be used alone or in combination.

The content of the resin material in the reinforcing filler-containing film is suitably 10 to 70% by weight. This results in a film or substrate having sufficient strength, low dielectric properties, and heat resistance. Such a content is such that the resin material as the resin paste, that is, the resin material itself can be heat-sealed when laminating films or laminating substrates (10
It may be realized by maintaining the content of (wt% or more).

As the molding method for forming the resin material of the present invention into a predetermined shape, there have been already mentioned ones, but a molding method, a compression method, an extrusion method and the like can be mentioned. According to a known method, the resin material of the present invention can be used. A method that can be inexpensively molded may be selected according to the purpose of use.

Regarding the electrical performance of the heat-resistant low-dielectric polymer material of the present invention, especially in the frequency band of 30 GHz or more, particularly in the millimeter wave band of 30 GHz to 300 GHz,
A dielectric constant (ε) of 1 or more, particularly 2.0 to 2.2, and a dielectric loss tangent (tan δ) of 0.01 or less, usually 0.0
A low dielectric electric insulating material having 015 to 0.005 can be obtained, and by using a reinforcing filler-containing electric insulating substrate that becomes an electric element, the strength of the substrate is improved, and the low dielectric electric insulating substrate itself. The coefficient of expansion can be made smaller and the thermal conductivity can be improved.

The insulation resistivity of the polymer material of the present invention is 2-5 × 10 ¹⁴ Ωcm or more in terms of volume resistivity in a normal state. Further, it has a high dielectric breakdown strength and exhibits excellent characteristics of 15 KV / mm or more, particularly 18 to 30 KV / mm.

This polymer material is excellent in heat resistance and can endure the heating temperature at the time of brazing and soldering.

In the present invention, the resin material used for the low frequency resin substrate is not particularly limited and may be any one that can be diluted with a solvent, can be hot pressed and can withstand etching, such as epoxy resin and phenol. Resins such as resins, polyolefin resins, polyimides, polyesters, polyphenylene oxides, melamine resins, cyanate ester resins and diallyl phthalates may be used either thermosetting or thermoplastic resins.

Particularly, an epoxy resin is preferably used,
Examples of the epoxy resin include bisphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and polyfunctional glycidyl amine resin.

Of these, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and polyfunctional glycidyl amine resin are preferable in terms of heat resistance.

Further, glass fiber or the like may be contained as a reinforcing material.

The high frequency resin substrate and the low frequency resin substrate are arranged to face each other at least on the ground conductor side,
At least a part of the conductor pattern formed on the high frequency resin substrate and a part of the conductor pattern formed on the low frequency resin substrate are connected by through holes.

The high frequency resin substrate and the low frequency resin substrate are arranged to face each other at least on the ground conductor side,
It is preferably glued. For the adhesion, a commonly used adhesive may be used, or a prepreg may be used instead. The adhesive is not particularly limited as long as it can bond the resin material and the metal material, and examples thereof include an epoxy adhesive.

The thickness of the adhesive layer made of such an adhesive is about 0.005 to 0.01 mm.

Further, the high frequency resin substrate and the low frequency resin substrate may each have a multilayer structure in which a plurality of layers are laminated. In the present invention, at least one or more conductor lines among these constituent layers may be electrically connected to each other by through holes. The ground conductor of the through hole connecting the high frequency resin substrate and the low frequency resin substrate is removed so as not to contact the through hole.

[0098]

EXAMPLES The present invention will now be described in more detail with reference to examples.

<Synthesis of High Frequency Substrate Substrate Material> 2500 g of pure water was placed in a stainless steel autoclave having a volume of 5 liters.
And polyvinyl alcohol as a suspending agent 2.
5 g was dissolved. 700 g of polypropylene "J Alloy 150G" (trade name, manufactured by Nippon Polyolefin Co., Ltd.) was put into this as an olefin polymer, and stirred and dispersed. Separately, 1.5 g of benzoyl peroxide as a radical polymerization initiator, 6 g of t-butylperoxymethacryloyloxyethyl carbonate as a radically polymerizable organic peroxide, 100 g of divinylbenzene and 200 g of styrene as a vinyl aromatic monomer. Dissolved in a mixture of
This solution was put into the autoclave and stirred.
Then, the autoclave was heated to 60 to 65 ° C. and stirred for 2 hours to impregnate polypropylene with a vinyl monomer containing a radical polymerization initiator and a radically polymerizable organic peroxide. Then, the temperature was raised to 80 to 85 ° C., and the temperature was maintained for 7 hours to complete the polymerization, followed by washing with water and drying to obtain a grafted precursor (b).

Then, this grafted precursor (b) was processed with a Labo Plastomill uniaxial extruder (manufactured by Toyo Seiki Seisaku-sho, Ltd.).
Was extruded at 200 ° C. for graft reaction to obtain a graft copolymer (K).

When the graft copolymer (K) was analyzed by pyrolysis gas chromatography, the weight ratio of polypropylene: divinylbenzene: styrene was 7
It was 0:10:20.

Regarding the molecular weight of the polymer, the weight average absolute molecular weight was measured using a high temperature GPC (manufactured by Waters Co., Ltd.). The molecular weight of polypropylene was 300,000 and divinylbenzene was 146,000. The carbon and hydrogen contents of this resin were quantified by elemental analysis. As a result, the ratio of the sum of carbon atoms and hydrogen atoms was 99% or more.

<Multilayer Circuit Board> The above high frequency resin sample was processed into a board shape and prepared. This substrate had a thickness of 0.127 mm and a dielectric constant of 2.2. Separately from this, a commercially available FR is used as a low frequency resin substrate.
-4, a thickness of 0.8 mm was used.

A copper foil having a thickness of 18 μm was adhered on one surface of each substrate to form a ground conductor. Then, the respective substrates were attached to each other with their ground conductors facing each other. At this time, necessary pattern forming processing such as removing the ground conductor in the through-hole portion for connection of the two substrates was performed. An epoxy adhesive was used for the bonding. The thickness of the thus laminated substrates was about 1 mm.

Next, using the obtained multilayer substrate, a circuit as shown in FIG. 4 was formed. That is, the high frequency amplification circuit 110 was formed on the high frequency resin substrate 10, and the power supply circuit 120 was formed on the low frequency resin substrate 20. Then, these circuits were connected to each other by through holes. Specifically, the output of the power supply circuit was connected through a through hole to supply power to the power supply connection portion of the amplifier circuit. The detailed circuit configuration of these is a well-known configuration mode, and the description thereof is omitted.

Further, as shown in FIG. 1, in the high frequency circuit board, a mounting hole 1a penetrating to the ground conductor is provided in a portion where the amplification element is mounted, and the mounting hole 1a is formed.
After accommodating the amplifying element therein, a sample to which wire bond connection was performed was prepared. At this time, the mounting hole was formed so that the distance from the inner circumference of the mounting hole to the amplification element, which is an electronic component, was 0.1 mm. Next, the amplification element was fixed to the ground conductor by brazing. The heating condition at this time is 12
The temperature was 0 ° C. for 20 minutes, but no damaged portion was confirmed on the substrate. In addition, the terminals of the amplifying element and the conductor lines are located substantially on the same plane.

Further, as shown in FIG. 3, a shield material was provided so as to cover the high frequency substrate, and the shield material and the ground conductor were connected via a conductor line and a through hole to prepare a sample.

At this time, the shield material is made of aluminum having a thickness of 5 mm and is formed in a box shape with one surface open so that the height from the surface of the substrate is 1 mm, and this is covered with the substrate. In this way, it was fixed by soldering.

The multilayer circuit board thus obtained is
As in the past, a high-frequency amplification board and a power board are provided separately,
Compared with the device that stores this, the size of the entire device,
It has been found that the size of the conventional device can be 30% or less in the horizontal direction and 30% or less in the vertical direction.

Further, it was found that the transmission characteristics of the sample in which the mounting element was provided and the amplification element was housed therein were improved as compared with the conventional device. It was also found that the temperature rise of the device was small.

[0111]

As described above, according to the present invention, a high-frequency circuit and a low-frequency circuit can coexist more compactly, and the high-frequency circuit board has low loss, heat resistance, and a fine pattern. It is possible to provide a small-sized, high-performance, low-priced multilayer circuit board that enables high-density mounting without becoming too high.

[0112]

[Brief description of drawings]

FIG. 1 is an external perspective view showing a configuration example of a multilayer circuit board according to the present invention.

FIG. 2 is a sectional view showing a configuration example of a multilayer circuit board according to the present invention.

FIG. 3 is a cross-sectional view showing a configuration example in which a shield material is provided on the multilayer circuit board of the present invention.

FIG. 4 is a block diagram showing a circuit configuration example of a multilayer circuit board according to the present invention.

[Explanation of symbols]

10 High frequency resin substrate 20 Low frequency resin substrate 11,21 Ground conductor 12, 13 Conductor line

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiaki Yamada             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. F-term (reference) 5E321 AA02 AA17 GG05                 5E346 AA12 AA14 AA32 AA42 AA43                       AA53 BB02 BB04 BB07 CC04                       CC09 CC32 DD02 DD12 DD32                       EE33 FF01 GG28 HH18 HH22

Claims (7)

[Claims] 1. A high-frequency resin substrate having a ground conductor closely arranged on one surface, and a low-frequency resin substrate having a ground conductor closely arranged on one surface. The substrate and the low-frequency resin substrate are arranged so as to face each other on the ground conductor side, and at least a part of the conductor pattern formed on the high-frequency resin substrate and the conductor pattern formed on the low-frequency resin substrate. A multi-layer circuit board that is connected to some of them with through holes. 2. The high frequency resin substrate has a thickness of 0.5 mm.
The multilayer circuit board according to claim 1, wherein: 3. The high frequency resin substrate is used in a frequency band of 30 GHz or higher, and the low frequency resin substrate is 500 MHz.
The multilayer circuit board according to claim 1 or 2, which is used at the following frequencies. 4. The multilayer circuit board according to claim 1, wherein the high-frequency circuit board is covered with a shield material. 5. A mounting hole penetrating to the ground conductor is formed in at least one of the electronic component mounting portions of the high frequency resin substrate, and the electronic component is housed in the mounting hole. Any multilayer circuit board. 6. The high frequency circuit board according to claim 5, wherein the conductor line of the high frequency circuit board and the connection terminal of the electronic component are substantially on the same plane. 7. The high-frequency resin substrate is a resin composition comprising one or more resins having a weight average absolute molecular weight of 1000 or more, and the sum of the number of carbon atoms and hydrogen atoms in the composition. Is 99% or more, and a part or all of the resin molecules are formed of a heat-resistant low dielectric polymer material having chemical bonds with each other, The multilayer circuit board according to claim 1.