JP2002261453A - Multilayer interconnection board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy both high-density wiring, solder-heat-resistance, insulating characteristics, and high-frequency transmission characteristics, related to a multilayer interconnection board in which an insulating layer containing organic material is laminated. SOLUTION: A multilayer interconnection board 4 is provided where, comprising an organic material, a plurality of insulating layers 1 provided with a wiring conductor 2 where at least one of upper and lower surfaces comprises a metal foil are laminated, and the insulating layers are electrically connected through a through conductor 3 where an insulating layer is formed between upper and lower wiring conductors 2. Related to the insulating layer 1, a coating layer 6 comprising polyphenylene ether organics is formed on the upper and lower surfaces of a liquid-crystal polymer layer 5. With holes easily opened for higher density of wiring, the coating layer 6 comprising polyphenylene ether organics is highly adhesive to the liquid-crystal polymer layer 5 and the wiring conductor 2 which has the same dielectric constant as the liquid-crystal polymer, resulting in no degradation in transmission characteristics at high frequency while excellent in solder-heat-resistance, insulating characteristics, and high-frequency transmission characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board used for electronic devices such as various AV devices, home appliances, communication devices, computers and their peripheral devices, and the like.
In particular, the present invention relates to a multilayer wiring board using a liquid crystal polymer layer as a part of an insulating layer.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board for forming a hybrid integrated circuit in which a predetermined electronic circuit is formed by mounting a large number of active parts such as semiconductor elements and passive parts such as capacitance elements and resistance elements is usually used. Formed by laminating multiple layers of wiring boards in which through holes are formed vertically by drilling in an insulating layer made of glass cloth impregnated with epoxy resin, and a plurality of wiring conductors are formed inside the through holes and on the surface of the insulating layer. Have been.

In general, current electronic devices are required to be small, thin, lightweight, high-performance, high-function, high-quality, and high-reliability, as typified by mobile communication devices. Electronic components such as hybrid integrated circuits mounted on
In order to respond to such demands for higher densities, multilayer wiring boards that make up electronic components are also required to have finer wiring conductors and thinner insulating layers.
It is becoming necessary to miniaturize the through holes. For this reason, in recent years, laser processing that can perform finer processing than drill processing has been used in order to make through holes finer.

However, an insulating layer formed by impregnating a glass cloth with an epoxy resin has a limitation in miniaturizing a through-hole because it is difficult to pierce the glass cloth with a laser. There is a problem that it is difficult to form a through-hole having a uniform diameter due to the uneven thickness.

In order to solve such problems, an insulating base material made by impregnating a non-woven fabric made of aramid resin fiber with an epoxy resin or an insulating base material obtained by applying an epoxy-based adhesive to a polyimide film is used as an insulating layer. A multilayer wiring board used has been proposed.

However, an insulating substrate using an aramid nonwoven fabric or a polyimide film has high hygroscopicity. If solder reflow is performed in a state of absorbing moisture, the moisture absorbed by the heat of the solder reflow vaporizes to generate gas, and an insulating interlayer is generated. With the problem of peeling.

In order to solve such problems, use of a liquid crystal polymer as a material for an insulating layer of a multilayer wiring board has been studied. The layer composed of the liquid crystal polymer is composed of rigid molecules and has a structure in which molecules are regularly arranged to some extent, and has a strong intermolecular force.
Shows high heat resistance, high elastic modulus, high dimensional stability, low moisture absorption,
There is no need to use a reinforcing material such as glass cloth, and it has features of being excellent in fine workability. Furthermore, even in a high-frequency region, it has a characteristic that it has a low dielectric constant and a low dielectric loss tangent, and has excellent high-frequency characteristics.

[0008] Utilizing the characteristics of such a liquid crystal polymer,
JP-A-8-97565 discloses that a circuit layer contains a first liquid crystal polymer and an adhesive layer containing a second liquid crystal polymer having a melting point lower than that of the first liquid crystal polymer is inserted between the circuit layers. A multilayer printed circuit board comprising: a high-frequency circuit board in which a thermoplastic liquid crystal polymer film and a metal foil are adhered to each other using an epoxy-based adhesive is proposed in JP-A-2000-269616. ing.

[0009]

SUMMARY OF THE INVENTION
The multilayer printed circuit board proposed in 8-97565 is
When an adhesive layer containing a liquid crystal polymer is inserted between the circuit layers and bonded by thermocompression bonding, the liquid crystal polymer molecules are rigid and difficult to move, so that they cannot enter the fine recesses on the surface of the circuit layer. There was a problem that a sufficient anchor effect could not be exerted, the adhesion between the circuit layer and the adhesive layer was poor, and insulation failure occurred in a high-temperature bias test.

The high-frequency circuit board proposed in Japanese Patent Application Laid-Open No. 2000-269616 has a small thickness caused by pressure during lamination since the dielectric constant of an epoxy-based adhesive is significantly different from that of a liquid crystal polymer. Due to the variation, there is a problem that transmission characteristics are degraded in a high frequency region, particularly in a frequency region of 100 MHz or higher.

The present invention has been devised in view of the problems of the prior art, and has as its object to provide a multilayer wiring board having high-density wiring and excellent solder heat resistance, insulation and high-frequency transmission characteristics. It is in providing.

[0012]

A multilayer wiring board according to the present invention is formed by laminating a plurality of insulating layers made of an organic material and having a wiring conductor made of a metal foil on at least one of upper and lower surfaces. A multilayer wiring board in which wiring conductors located above and below the insulating layer are electrically connected via through conductors formed in the insulating layer, and the insulating layer is provided on upper and lower surfaces of the liquid crystal polymer layer. It is characterized in that a coating layer made of a polyphenylene ether organic material is formed.

According to the multilayer wiring board of the present invention, the insulating layer is formed by forming a coating layer made of a polyphenylene ether organic material on the surface of the liquid crystal polymer layer.
It is possible to form a fine through-hole, and as a result, it is possible to obtain a multilayer wiring board having high-density wiring, and to obtain a dielectric constant of a liquid crystal polymer layer and a coating layer made of a polyphenylene ether-based organic material. Since the frequency behaviors are substantially equal, a multilayer wiring board having excellent high-frequency transmission characteristics without causing a decrease in transmission characteristics in a high-frequency region even when slight thickness variations occur during lamination can be obtained. Furthermore, since the coating layer made of a polyphenylene ether-based organic material exhibits the same degree of hydrophobicity as the liquid crystal polymer layer, both resins have good compatibility and excellent adhesion, and the coating layer has a random molecular structure. Since it is composed of molecules that are relatively easily moved by heat, it can penetrate into fine recesses on the surface of the liquid crystal polymer layer and exhibit a sufficient anchoring effect, resulting in good adhesion between the liquid crystal polymer layer and the coating layer, No insulation failure occurs in the bias test. Furthermore, since the liquid crystal polymer has low hygroscopicity, no gas is generated due to moisture vaporization during solder reflow, and no separation occurs between the insulating layers.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a multilayer wiring board according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an example of an embodiment of a hybrid integrated circuit in which a semiconductor element is mounted on a multilayer wiring board according to the present invention. FIG. 2 is a sectional view showing the multilayer wiring board shown in FIG. It is principal part sectional drawing of. In these figures, reference numeral 1 denotes an insulating layer, 2 denotes a wiring conductor, and 3 denotes a through conductor, and these mainly constitute a multilayer wiring board 4 of the present invention. In this example, a multi-layer wiring board 4 formed by laminating four insulating layers 1 is shown.

The insulating layer 1 is composed of a liquid crystal polymer layer 5 and a covering layer 6 made of a polyphenylene ether-based organic substance formed on the surface thereof, and is mounted on the wiring conductor 2 and the multilayer wiring board 4. It has a function as a support for the electronic component 7.

Here, the liquid crystal polymer means a polymer having a liquid crystal state or an optically birefringent property when melted, and generally a lyotropic liquid crystal polymer which exhibits liquid crystallinity in a solution state or a thermotropic liquid crystal polymer which exhibits liquid crystallinity when melted. It includes a liquid crystal polymer or a liquid crystal polymer of all types 1, 2, and 3 classified by heat distortion temperature. The polyphenylene ether-based organic material is a polyphenylene ether resin or a resin in which various functional groups are bonded to polyphenylene ether, or a derivative or a derivative thereof.
It means a polymer.

The liquid crystal polymer preferably has a melting point at a temperature of 200 to 400 ° C., particularly 250 to 350 ° C., from the viewpoint of temperature cycle reliability, solder heat resistance and workability. Light stabilizers such as an antioxidant for improving thermal stability and an ultraviolet absorber for improving light resistance, and a halogen or phosphoric acid for improving flame retardancy, as long as the physical properties of the compound are not impaired. -Based flame retardants, antimony-based compounds, flame-retardant aids such as zinc borate, barium metaborate, and zirconium oxide; higher fatty acids and higher fatty acid esters to improve lubricity; higher fatty acid metal salts; and fluorocarbon-based interfaces Lubricant such as activator, aluminum oxide / silicon oxide / titanium oxide / barium oxide / strontium oxide for adjusting thermal expansion coefficient and / or improving mechanical strength Zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate, aluminum borate, barium stannate, barium zirconate, strontium zirconate, etc. It may contain a filler.

The particle shape of the above-mentioned filler and the like includes a substantially spherical shape, a needle shape, a flake shape and the like, and a substantially spherical shape is preferable from the viewpoint of filling properties. The particle size is usually about 0.1 to 15 μm, which is smaller than the thickness of the liquid crystal polymer layer 5.

Further, the liquid crystal polymer layer 5 has its surface buffed, blasted, brushed, plasma-treated, corona-treated, ultraviolet-treated in order to enhance the adhesion with the coating layer 6 made of a polyphenylene ether-based organic substance. The center line surface roughness Ra is 0.05 to 5μ by using a method such as chemical treatment.
It is preferable to roughen so as to have a value of m. The center line surface roughness Ra is 0.05 from the viewpoint of preventing peeling of the liquid crystal polymer layer 5 and the coating layer 6 during solder reflow.
μm or more, and from the viewpoint of preventing air entrapment when forming the coating layer 6 on the surface, it is 5 μm or more.
It is preferably not more than μm. Therefore, the liquid crystal polymer layer 5 has a center line surface roughness Ra of 0.05 to 5 μm.
It is preferable to have a rough surface.

Next, a coating layer 6 made of a polyphenylene ether-based organic substance formed on the surface of the liquid crystal polymer layer 5
Has the function of an adhesive when the wiring conductor 2 is adhered to the insulating layer 1 and also functions as an adhesive when the insulating layers 1 are laminated.

The coating layer 6 contains 30 to 90% by volume of a polyphenylene ether-based organic material such as a polyphenylene ether resin or a derivative thereof, or a polymer alloy thereof. From the viewpoint, it is preferable to contain a thermosetting polyphenylene ether such as an allyl-modified polyphenylene ether.

When the content of the polyphenylene ether-based organic substance is less than 30% by volume, the kneadability with a filler described later tends to decrease. On the other hand, when the content exceeds 90% by volume, the surface of the liquid crystal polymer layer 5 is exposed. When forming the coating layer 6 on the
The thickness variation of the coating layer 6 tends to increase. Therefore, the content of the polyphenylene ether-based organic substance is 30 to
A range of 90% by volume is preferred.

The coating layer 6 made of a polyphenylene ether-based organic material has a functional property capable of undergoing a polymerization reaction from the viewpoint of improving the adhesion to the liquid crystal polymer layer 5 and the adhesion to the wiring conductor 2 and the through conductor 3. It is preferable to contain an additive such as a polyfunctional monomer or a polyfunctional polymer having two or more groups, for example, it is preferable to contain triallyl cyanurate, triallyl isocyanurate and a polymer thereof. .

Further, the coating layer 6 includes a rubber component for adjusting the elastic modulus, an antioxidant for improving thermal stability,
Light stabilizers such as ultraviolet absorbers to improve light resistance, halogen-based or phosphoric-based flame retardants to improve flame retardancy, antimony compounds, zinc borate, barium metaborate, and zirconium oxide. Such as flame retardant aids, lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts and fluorocarbon surfactants for improving lubricity;
Aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide, zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate for adjusting the thermal expansion coefficient and improving mechanical strength -Fillers such as barium titanate-strontium titanate-calcium titanate-aluminum borate-barium stannate-barium zirconate-strontium zirconate; A coupling agent such as a silane coupling agent or a titanate coupling agent for increasing the mechanical strength may be contained.

In particular, when the insulating layer 1 is laminated and pressed, from the viewpoint of suppressing the fluidity of the coating layer 6 and preventing the displacement of the through conductor 3 and the thickness variation of the coating layer 6, the coating layer 6 is formed. It is preferable to contain 10% by volume or more of an inorganic insulating powder as a filler. Further, from the viewpoint of preventing peeling during solder reflow at the bonding interface with the liquid crystal polymer layer 5 and the bonding interface with the wiring conductor 2, the content of the filler should be reduced.
It is preferable to be 70% by volume or less. Therefore, it is preferable that the coating layer 6 made of a polyphenylene ether-based organic substance contains 10 to 70% by volume of a filler.

The shape of the above-mentioned filler and the like is substantially spherical.
There are a needle shape, a flake shape and the like, and a substantially spherical shape is preferable from the viewpoint of filling properties. The particle diameter is about 0.1 to 15 μm, which is smaller than the thickness of the coating layer 6.

According to the multilayer wiring board 4 of the present invention, since the dielectric constant of the liquid crystal polymer layer 5 and the covering layer 6 made of polyphenylene ether-based organic material are substantially equal, even if a slight thickness variation occurs during the lamination. The multilayer wiring board 4 having excellent high-frequency transmission characteristics without causing a decrease in transmission characteristics in a high-frequency region can be provided. In addition, since the coating layer 6 exhibits the same degree of hydrophobicity as the liquid crystal polymer layer 5, the resin is well-adapted to each other, so that the adhesive property is excellent, and the coating layer 6 has a random molecular structure and is relatively easily moved by heat. Since it is composed of molecules, it can penetrate into fine recesses on the surface of the liquid crystal polymer layer 5 and exhibit a sufficient anchor effect. As a result, the adhesion between the liquid crystal polymer layer 5 and the coating layer 6 becomes good, and the insulation is obtained in a high temperature bias test. The multilayer wiring board 4 which is excellent in heat resistance and insulation without causing defects can be obtained.

The insulating layer 1 has, for example, a particle size of 0.1.
A paste obtained by adding a thermosetting polyphenylene ether resin, a solvent, a plasticizer, a dispersant, and the like to an inorganic insulating powder such as silicon oxide having a thickness of about 15 μm is applied to the upper and lower surfaces of the liquid crystal polymer layer 5 by a known doctor blade method. After forming the coating layer 6 by employing a sheet molding method such as that described above, or after forming the coating layer 6 on the surface of the liquid crystal polymer layer 5 by immersing the liquid crystal polymer layer 5 in the above paste and vertically pulling it up,
It is manufactured by heating and drying it at a temperature of 60 to 100 ° C. for 5 minutes to 3 hours.

The thickness of the insulating layer 1 is preferably from 10 to 200 μm from the viewpoint of securing insulation reliability, and from the viewpoint of securing high heat resistance, low moisture absorption and high dimensional stability. Preferably, the thickness of the liquid crystal polymer layer 5 is set in the range of 40 to 90% of the thickness of the insulating layer 1.

In the insulating layer 1, a wiring conductor 2 is formed on at least one of the upper and lower surfaces. The wiring conductor 2 has a thickness of about 2 to 30 μm and is made of a highly conductive metal foil such as copper or gold, and electrically connects the electronic components 7 mounted on the multilayer wiring board 4 to an external electric circuit (not shown). It has the function of connecting to

In order to prevent the occurrence of voids around the wiring conductor 2 when a plurality of insulating layers 1 are laminated, such a wiring conductor 2 is provided at least on the surface of the wiring conductor 2 on the covering layer 6. It is preferable that the surface of the coating layer 6 is buried so as to be flat. When the porosity of the coating layer 6 in the dry state is set to 3 to 40% by volume when the wiring conductor 2 is embedded in the coating layer 6, the coating layer
The resin can be flattened without causing resin swelling, and the air trapped between the wiring conductor 2 and the coating layer 6 can be easily discharged to prevent air bubbles from being trapped. When the porosity in the dry state exceeds 40% by volume,
After pressurizing and heating and curing the laminated insulating layer 1, pores remain in the coating layer 6, and the pores may adsorb moisture in the air and the insulating property may be reduced. It is preferable that the porosity of the layer 6 in a dry state is in the range of 3 to 40% by volume.

The porosity of the coating layer 6 in the dry state can be adjusted by appropriately controlling drying conditions such as a drying temperature and a heating rate when the coating layer 6 is applied on the surface of the liquid crystal polymer layer 5 and dried. By doing so, the porosity can be set to a desired value.

It is preferable that the thickness of the coating layer 6 located between the wiring conductor 2 and the liquid crystal polymer layer 5 be 3 to 35 μm. Assuming that the thickness of the coating layer 6 located between the wiring conductor 2 and the liquid crystal polymer layer 5 is 3 to 35 μm,
By bringing the wiring conductor 2 and the liquid crystal polymer layer 5 having a low dielectric loss tangent close to each other, the dielectric loss tangent around the wiring conductor 2 can be reduced, and as a result, the transmission characteristics in a high frequency region, particularly in a frequency region of 100 MHz or more, are improved. be able to. If the thickness of the coating layer 6 is less than 3 μm, the stress generated by the thermal expansion and thermal contraction of the wiring conductor 2 cannot be effectively relieved by the coating layer 6, and cracks are formed from the corners of the wiring conductor 2. 35 μm
If it exceeds, the effect of lowering the dielectric loss tangent around the wiring conductor 2 tends to decrease. Accordingly, the thickness of the coating layer 6 located between the wiring conductor 2 and the liquid crystal polymer layer 5 is 3 to 35 μm.
It is preferable to set the range of m.

Further, the wiring conductor 2 provided on the insulating layer 1
Has a trapezoidal shape in which the length of the base on the insulating layer 1 side is shorter than the length of the opposing base, and the angle between the base and the side on the insulating layer 1 side is 95 to 150 °. It is preferable that The cross-sectional shape in the width direction of the wiring conductor 2 disposed on the insulating layer 1 is trapezoidal in which the length of the base on the side of the insulating layer 1 is shorter than the length of the opposite base, and the width of the base on the side of the insulating layer 1 By setting the angle between the side and the side at 95 to 150 °, when the wiring conductor 2 is embedded in the coating layer 6, the wiring conductor 2
Can be easily embedded in the coating layer 6. In addition, from the viewpoint of burying without entrapping air bubbles, it is preferable that the angle between the bottom side and the side of the insulating layer 1 is 95 ° or more, and from the viewpoint of miniaturizing the wiring conductor 2, it is 15 °.
Preferably, it is 0 ° or less.

The thickness x (μm) of the coating layer 6 located between the short base of the wiring conductor 2 and the liquid crystal polymer layer 5 between the insulating layers 1 is set between the upper and lower liquid crystal polymer layers 5. Is T (μm), and the thickness of the wiring conductor 2 is t (μm).
m), 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35
μm (8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦ 32 μm
m) is preferred.

The distance between the liquid crystal polymer layers 6 is T (μm),
Assuming that the thickness of the wiring conductor 2 is t (μm), the thickness x (μ) of the covering layer 6 made of a polyphenylene ether-based organic material between the short base of the wiring conductor 2 and the liquid crystal polymer layer 5
m) is set to 3 μm ≦ 0.5T−t ≦ x ≦ 0.5T ≦ 35 μm, so that the distance between the short base of the wiring conductor 2 and the liquid crystal polymer layer 5 and the long base of the wiring conductor 2 are long. The difference in the distance between the liquid crystal polymer layers 5 can be reduced to less than t (μm), the variation in the dielectric loss tangent around the wiring conductor 2 can be reduced, and as a result, the transmission characteristics can be prevented from deteriorating. Accordingly, the thickness x (μ) of the coating layer 6 made of a polyphenylene ether-based organic substance and located between the trapezoidal upper bottom surface of the wiring conductor 2 and the liquid crystal polymer layer 5.
m), when the distance between the liquid crystal polymer layers 6 is T (μm) and the thickness of the wiring conductor 2 is t (μm), 3 μm ≦ 0.5
It is preferable that Tt ≦ x ≦ 0.5T ≦ 35 μm.

Such a wiring conductor 2 is formed by depositing a metal foil made of, for example, copper, which is patterned by a subtractive method using a known photoresist, on a precursor sheet to be the insulating layer 1 by a transfer method or the like. It is formed by this. First, a metal foil transfer film is prepared by bonding a metal foil made of copper on a film serving as a support with an adhesive, and then the metal foil on the film is subjected to a subtractive method using a known photoresist. Is used to etch in a pattern. At this time, the side surface on the front side of the pattern
Since the contact time with the etching solution is longer than that of the side surface on the film side, etching is easy, and the cross-sectional shape in the width direction of the pattern can be trapezoidal. The trapezoidal shape can be formed into a trapezoidal shape in which the angle between the short base and the side is 95 to 150 ° by adjusting the concentration of the etching solution and the etching time. Then, this metal foil transfer film is laminated on a precursor sheet to be the insulating layer 1, and the temperature is 100 to 200 ° C. and the pressure is 0.5 to 10 MPa for 10 minutes to 1 hour.
After hot pressing for a period of time, the film serving as the support is peeled off and the metal foil is transferred to the surface of the precursor sheet serving as the insulating layer 1, so that the trapezoidal upper and lower sides become the coating layer 6 made of a polyphenylene ether-based organic material. The buried wiring conductor 2 can be formed.

The thickness x (μm) of the coating layer 6 between the liquid crystal polymer layer 5 and the base having the shorter length of the wiring conductor 2.
Can be set in the range of 3 to 35 μm by adjusting the pressure of the hot press during the transfer of the metal foil. The surface of the wiring conductor 2 is preferably roughened by a process such as buffing, blasting, brushing, or chemical treatment in order to enhance the adhesion to the coating layer 6.

The insulating layer 1 has a diameter of 20 to 150 μm.
The through conductor 3 is formed to a degree. The penetrating conductor 3 has a function of electrically connecting the wiring conductors 2 positioned above and below the insulating layer with the insulating layer interposed therebetween. The hole is formed by embedding a conductive paste made of copper, silver, gold, solder, or the like by a conventionally known screen printing method.

According to the multilayer wiring board 4 of the present invention, since the insulating layer 1 has the coating layer 6 made of a polyphenylene ether-based organic material on the upper and lower surfaces of the liquid crystal polymer layer 5, the liquid crystal polymer layer 5 is high. It has heat resistance, high elastic modulus, high dimensional stability, and low hygroscopicity, making it possible to form the insulating layer 1 without using a reinforcing material such as glass cloth. As a result, laser drilling is easy. Thus, fine and uniform through holes can be formed.

In such a multilayer wiring board 4, after forming the through conductor 3 at a desired position of the precursor sheet to be the insulating layer 1 manufactured by the method described above, a patterned metal foil of, for example, copper is formed. , Temperature is 100 ~ 200 ℃ and pressure is 0.5 ~ 10
Transfer by hot pressing under the condition of MPa for 10 minutes to 1 hour,
These are laminated and finally the temperature is 150-300 ° C and the pressure is 0.
It is manufactured by hot-pressing under conditions of 5 to 10 MPa for 30 minutes to 24 hours to completely cure.

Thus, according to the multilayer wiring board 4 of the present invention, since the insulating layer 1 has the coating layer 6 made of a polyphenylene ether-based organic material on the surface of the liquid crystal polymer layer 5, the high-frequency transmission characteristics are improved. The multilayer wiring board 4 is excellent and has excellent moisture resistance, solder heat resistance, and insulation properties.

The multilayer wiring board 4 of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. Manufactured the multilayer wiring board 4 by laminating the four insulating layers 1;
The multilayer wiring board 4 may be manufactured by laminating more than one insulating layer 1. Further, on the upper and lower surfaces of the multilayer wiring board 4 of the present invention,
One, two, or three or more build-up layers or solder resist layers composed of an insulating layer mainly containing an organic resin may be formed.

[0045]

Next, the multilayer wiring board of the present invention was evaluated by producing the following samples. (Example) First, a spherical fused silica having an average particle diameter of 0.6 μm was added to a thermosetting polyphenylene ether resin having a content of 4 μm.
0% by volume, toluene as a solvent and a catalyst for accelerating the curing of the organic resin were added thereto, and mixed for 1 hour to prepare a varnish. Next, the melting point
A liquid crystal polymer layer having a thickness of 35 μm and a center line surface roughness Ra of 0.10 μm is prepared by performing a plasma treatment on the surface of the liquid crystal polymer layer at 320 ° C. The varnish is applied to the upper surface of the liquid crystal polymer layer by a doctor blade method. Then, a dried thermosetting polyphenylene ether coating layer having a thickness of about 20 μm was formed. Then, a polyphenylene ether coating layer was similarly formed on the lower surface of the liquid crystal polymer layer to produce a precursor sheet to be an insulating layer. Furthermore, in this precursor sheet,
A through hole having a diameter of 65 μm was formed by a CO ₂ laser, and a conductive paste containing copper powder and an organic binder was embedded in the through hole by screen printing to form a through conductor.

Next, a transfer supporting film having a 12 μm-thick copper foil formed in a circuit shape and a precursor sheet serving as an insulating layer having a through conductor formed thereon were aligned with each other, and were subjected to 3 MPa by a vacuum laminator. Then, the transfer support film was peeled off, and the wiring conductor was embedded on the precursor sheet. Finally, four precursor sheets on which the wiring conductors are formed are superimposed, and a pressure of 3 MPa and a temperature of 200 ° C.
A heating treatment was performed for a period of time to complete the curing, thereby obtaining a multilayer wiring board.

The test board for evaluating the insulating property is used for forming a wiring conductor having a comb-tooth pattern with a wiring width of 50 μm and a wiring interval of 50 μm in a multilayer wiring board, and for evaluating the transmission characteristics. In this test board, a wiring conductor having a strip line structure was formed inside a multilayer wiring board.

(Comparative Example 1) The multilayer wiring board used for Comparative Example 1 was prepared by first forming a circuit-like wiring using a photoresist on a liquid crystal polymer layer having a melting point of 320.degree. A conductor is formed, then a through hole having a diameter of 65 μm is formed by a CO ₂ laser, and a conductor paste containing copper powder and an organic binder is further embedded in the through hole by screen printing to form a through conductor. After making the boards, these circuit boards are melted at 280 ° C.
285 under a pressure of 1 MPa with a liquid crystal polymer layer of
It was manufactured by hot pressing at a temperature of 5 ° C. for 5 minutes.

(Comparative Example 2) The multilayer wiring board used for Comparative Example 2 was prepared by using a liquid crystal polymer layer having a melting point of 320 ° C. and a copper foil bonded to the surface thereof via an epoxy resin adhesive. It was manufactured in the same manner as the multilayer wiring board for Comparative Example 1.

The insulation was evaluated by subjecting the sample to a high-temperature bias test at an applied voltage of 5.5 V at a temperature of 130 ° C. and a relative humidity of 85%, and measuring the insulation resistance between the wiring conductors after 168 hours. Evaluation was made by comparing the amount of change before and after the test.
The transmission characteristics were evaluated by measuring the transmission characteristics in a frequency range of 100 MHz to 40 GHz using a sample having a strip structure.

Table 1 shows the evaluation results of the insulating properties, and Table 2 shows the evaluation results of the transmission characteristics.

[0052]

[Table 1]

[0053]

[Table 2]

From Table 1, it was found that the insulation resistance of the multilayer wiring board of Comparative Example 1 after the high-temperature bias test was as small as 3.5 × 10 ⁶ Ω, and was inferior in heat resistance. Also, from Table 2,
It was found that the transmission characteristics of the multilayer wiring board of Comparative Example 2 were degraded to -1.0 dB or less in a high frequency region of 20 GHz or more, and were inferior to the high frequency transmission characteristics.

On the other hand, the multilayer wiring board of the present invention
Even after the high-temperature bias test, the insulation resistance was as large as 4.3 × 10 ¹⁰ Ω, and the transmission characteristics were as small as -0.51 dB even in the high frequency region of 40 GHz.

[0056]

According to the multilayer wiring board of the present invention, since the insulating layer is formed by forming a coating layer made of a polyphenylene ether-based organic material on the surface of the liquid crystal polymer layer, fine through holes are formed. Processing becomes possible, and as a result, a multilayer wiring board having high-density wiring can be obtained. In addition, since the frequency behavior of the dielectric constant of the liquid crystal polymer layer and the covering layer made of polyphenylene ether-based organic material are substantially equal, Further, a multilayer wiring board having excellent high-frequency transmission characteristics without causing a decrease in transmission characteristics in a high-frequency region even if slight thickness variations occur during lamination. Furthermore, the coating layer made of a polyphenylene ether-based organic material exhibits the same degree of hydrophobicity as the liquid crystal polymer layer, so that both resins are compatible and have excellent adhesion, and the coating layer has a random molecular structure. Since it is composed of molecules that are relatively easily moved by heat, it can penetrate into fine concaves on the surface of the liquid crystal polymer layer and exhibit a sufficient anchor effect. As a result, the adhesion between the liquid crystal polymer layer and the coating layer becomes good, and high-temperature bias No insulation failure occurs in the test. Furthermore, since the liquid crystal polymer has low hygroscopicity, no gas is generated due to moisture vaporization during solder reflow, and no separation occurs between the insulating layers.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of an embodiment of a hybrid integrated circuit in which a semiconductor element is mounted on a multilayer wiring board of the present invention.

FIG. 2 is a sectional view of a main part of the multilayer wiring board of the present invention.

[Explanation of symbols]

1 ... insulating layer 2 ... wiring conductor 3 ... through conductor 4 ... multilayer wiring board 5 ... liquid crystal polymer layer 6 ... polyphenylene ether Coating layer composed of organic organic substance T · · · · · · Distance between liquid crystal polymer layers t · · · · · · thickness of wiring conductor x · · · · between the top and bottom surface of trapezoidal wiring conductor and liquid crystal polymer layer The thickness of the coating layer made of polyphenylene ether organic material

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E338 AA03 BB02 BB25 CC01 CD05 CD22 EE11 EE27 5E346 AA12 AA15 CC08 CC32 DD12 DD32 EE08 EE14 EE19 FF18 GG15 GG22 HH06 HH11 HH26

Claims (7)

[Claims] 1. An insulating material comprising a plurality of insulating layers made of an organic material and having a wiring conductor made of a metal foil disposed on at least one of upper and lower surfaces, and located above and below the insulating layer. A multilayer wiring board in which the wiring conductors are electrically connected via a through conductor formed in the insulating layer, wherein the insulating layer has a coating layer made of a polyphenylene ether-based organic material on upper and lower surfaces of a liquid crystal polymer layer. A multilayer wiring board characterized by being formed. 2. The multilayer wiring board according to claim 1, wherein the upper and lower surfaces of the liquid crystal polymer layer are rough surfaces having a center line surface roughness Ra of 0.05 to 5 μm. 3. The multilayer wiring board according to claim 1, wherein said coating layer contains 10 to 70% by volume of an inorganic insulating powder. 4. The multilayer wiring board according to claim 1, wherein the polyphenylene ether-based organic substance is a thermosetting polyphenylene ether. 5. The multilayer wiring according to claim 1, wherein the thickness of the coating layer located between the liquid crystal polymer layer and the wiring conductor is 3 to 35 μm. substrate. 6. A cross-sectional shape in a width direction of the wiring conductor provided on the insulating layer is a trapezoid in which a length of a base on the side of the insulating layer is shorter than a length of an opposite base. The multilayer wiring board according to any one of claims 1 to 5, wherein the angle formed between the bottom side and the side of the layer is 95 to 150 °. 7. A thickness x (μm) of the coating layer located between the short bottom of the wiring conductor and the liquid crystal polymer layer between the insulating layers, and a thickness x (μm) between the upper and lower liquid crystal polymer layers. When the distance is T (μm) and the thickness of the wiring conductor is t (μm), 3 μm ≦ 0.5T−t ≦ x ≦
0.5T ≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm,
7. The multilayer wiring board according to claim 6, wherein 1 μm ≦ t ≦ 32 μm).