JP2006191145A - Multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfy the densification and solder thermal resistance of wiring and both an insulation property and high-frequency transmission characteristics in a multilayer printed circuit board formed by laminating insulating layers each containing an organic material. <P>SOLUTION: In the multilayer wiring board 4 made of an organic material, which is formed by laminating a plurality of the insulating layers 1 in which a wiring conductor 2 made of a metal foil is arranged to at least one surface of upper and lower surfaces and which is connected electrically between the wiring conductors 2 located above and below the insulating layer through a penetration conductor 3 formed in the insulating layer, the insulating layer 1 is made by forming a coating layer 6 made of a polyphenylene ether organic substance on the upper and lower surfaces of a liquid crystal polymer layer 5 in which the surface is plasma-treated. Perforating processing is easy and the densification of the wiring becomes possible. Moreover, the coating layer 6 made of a polyphenylene ether organic substance exhibits high adhesive property with the liquid crystal polymer layer 5 and the wiring conductors 2, and does not lower the transmission characteristics in high-frequency by exhibiting the same dielectric constant as the liquid crystal polymer, and is excellent in the solder thermal resistance, the insulation property and the high-frequency transmission characteristics. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a multilayer wiring board used in various AV equipment, home appliances, communication equipment, computers, and electronic equipment such as peripheral equipment thereof, and in particular, multilayer wiring using a liquid crystal polymer layer as a part of an insulating layer. It relates to a substrate.

  Conventionally, a multilayer wiring board for forming a hybrid integrated circuit in which a predetermined electronic circuit is configured by mounting a large number of active components such as semiconductor elements and passive components such as capacitance elements and resistance elements is usually an epoxy resin on a glass cloth. Through-holes are formed in an insulating layer formed by impregnating the top and bottom with a drill, and a plurality of wiring boards each having a plurality of wiring conductors formed in the through-holes and on the surface of the insulating layer are laminated.

  In general, current electronic devices are required to be small, thin, lightweight, high performance, high functionality, high quality, and high reliability, as represented by mobile communication devices. Electronic components such as hybrid integrated circuits are required to be smaller and higher in density, and in order to meet the demand for higher density, multilayer wiring boards constituting electronic components are also used as wiring conductors. Therefore, it is necessary to reduce the thickness of the insulating layer, the thickness of the insulating layer, and the size of the through hole. For this reason, in recent years, in order to miniaturize the through hole, laser processing capable of performing fine processing rather than drill processing has been used.

  However, an insulating layer formed by impregnating an epoxy resin into a glass cloth has a limit in miniaturizing the through-hole because it is difficult to drill the glass cloth with a laser, and the thickness of the glass cloth is not sufficient. For the sake of uniformity, there is a problem that it is difficult to form a through hole having a uniform hole diameter.

  In order to solve such problems, an insulating base material in which a non-woven fabric made of aramid resin fibers is impregnated with an epoxy resin, or an insulating base material in which an epoxy adhesive is applied to a polyimide film is used as an insulating layer. A wiring board has been proposed.

  However, insulating base materials using aramid nonwoven fabric and polyimide film are highly hygroscopic, and when solder reflow is performed while moisture is absorbed, moisture absorbed by the heat of solder reflow is vaporized and gas is generated and delaminated between insulating layers. There was a problem such as.

  In order to solve such problems, it has been studied to use a liquid crystal polymer as a material for an insulating layer of a multilayer wiring board. The layer made of liquid crystal polymer is composed of rigid molecules and has a structure in which the molecules are regularly arranged to some extent and the intermolecular force is strong, so it has high heat resistance, high elastic modulus, and high dimensional stability. -It has low hygroscopicity, does not require the use of a reinforcing material such as glass cloth, and is excellent in fine workability. Furthermore, the high frequency region also has the characteristics of low dielectric constant and low dielectric loss tangent and excellent high frequency characteristics.

Taking advantage of such characteristics of the liquid crystal polymer, Japanese Patent Application Laid-Open No. 8-97565 discloses a second circuit layer including a first liquid crystal polymer and a melting point lower than the melting point of the first liquid crystal polymer between the circuit layers. A multilayer printed circuit board in which an adhesive layer containing a liquid crystal polymer is inserted has been proposed, and JP-A-2000-269616 uses a thermoplastic liquid crystal polymer film and a metal foil with an epoxy adhesive. A high-frequency circuit board that has been bonded together has been proposed.
JP-A-8-97565 Japanese Unexamined Patent Publication No. 2000-269616

  However, in the multilayer printed circuit board proposed in Japanese Patent Laid-Open No. 8-97565, the liquid crystal polymer molecules are rigid and difficult to move when the circuit layer is bonded by thermocompression bonding with an adhesive layer containing a liquid crystal polymer interposed therebetween. For this reason, it is not possible to enter the fine recesses on the surface of the circuit layer, and as a result, a sufficient anchor effect cannot be exhibited, and the adhesion between the circuit layer and the adhesive layer is poor, resulting in poor insulation in the high temperature bias test. It had the problem that it would occur.

  In addition, the high frequency circuit board proposed in Japanese Patent Application Laid-Open No. 2000-269616, because the dielectric constant of the epoxy adhesive is significantly different from the dielectric constant of the liquid crystal polymer, due to slight thickness variations caused by pressure during lamination, There is a problem that transmission characteristics deteriorate 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 an object thereof is to provide a multilayer wiring board having high-density wiring and excellent solder heat resistance, insulation, and high-frequency transmission characteristics. There is.

  The multilayer wiring board of the present invention is formed by laminating a plurality of insulating layers made of an organic material and provided with wiring conductors made of metal foil on at least one of the upper and lower surfaces, and sandwiching the insulating layers therebetween. A multilayer wiring board in which wiring conductors located in each other are electrically connected via through conductors formed in an insulating layer, and the insulating layer is formed of a polyphenylene ether system on the upper and lower surfaces of a liquid crystal polymer layer whose surface is plasma-treated. It is characterized by forming a coating layer made of an organic substance.

  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 organic material on the surface of the liquid crystal polymer layer whose surface has been plasma-treated, fine through holes are formed. As a result, a multilayer wiring board having high-density wiring can be obtained, and the frequency behavior of the dielectric constant of the liquid crystal polymer layer and the coating layer made of polyphenylene ether-based organic substance is almost equal. Therefore, even if slight thickness variations occur during the lamination, a multilayer wiring board having excellent high frequency transmission characteristics that does not cause deterioration of transmission characteristics in the high frequency region can be obtained.

  Furthermore, the coating layer made of polyphenylene ether-based organic material exhibits the same level of hydrophobicity as the liquid crystal polymer layer, so that the two resins are well-familiar with each other and have excellent adhesion, and the coating layer has a random molecular structure. Because it is composed of molecules that are relatively easily moved by heat, it can penetrate into the minute recesses on the surface of the liquid crystal polymer layer and exert a sufficient anchoring effect. As a result, the adhesion between the liquid crystal polymer layer and the coating layer is improved, resulting in a high temperature bias. Insulation failure does not occur in the test. Furthermore, since the liquid crystal polymer has a low hygroscopic property, moisture is not vaporized during reflow of solder, gas is not generated, and separation between insulating layers does not occur.

  Next, the multilayer wiring board of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of a hybrid integrated circuit in which a semiconductor element is mounted on the multilayer wiring board of the present invention, and FIG. 2 is a main part of the multilayer wiring board shown in FIG. It is sectional drawing. In these drawings, reference numeral 1 denotes an insulating layer, 2 denotes a wiring conductor, and 3 denotes a through conductor. The multilayer wiring board 4 of the present invention is mainly constituted by these. In this example, a multilayer wiring board 4 in which four insulating layers 1 are laminated is shown.

  The insulating layer 1 is composed of a liquid crystal polymer layer 5 and a coating layer 6 made of a polyphenylene ether organic material deposited on the surface thereof, and an electronic component 7 mounted on the wiring conductor 2 or the multilayer wiring board 4. It has a function as a support.

  Here, the liquid crystal polymer refers to a polymer having a property of being in a liquid crystal state or optically birefringent when melted, generally a lyotropic liquid crystal polymer exhibiting liquid crystallinity in a solution state, or a thermotropic liquid crystal polymer exhibiting liquid crystallinity when melted, Alternatively, all liquid crystal polymers of type 1, type 2, and type 3 classified by the heat distortion temperature are included. The polyphenylene ether-based organic material means a polyphenylene ether resin, a resin in which various functional groups are bonded to polyphenylene ether, or a derivative / polymer thereof.

  In addition, 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, and further has physical properties as a layer. Light stabilizers such as antioxidants to improve thermal stability and UV absorbers to improve light resistance, and halogen or phosphoric acid difficult to improve flame retardancy within the range that does not impair Flame retardants, flame retardant aids such as antimony compounds, zinc borate, barium metaborate, zirconium oxide, higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, fluorocarbon surfactants to improve lubricity, etc. Aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirco for adjusting lubricant, adjusting thermal expansion coefficient and / or improving mechanical strength Filling with U.S., 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. You may contain material.

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

  Further, the surface of the liquid crystal polymer layer 5 is roughened by using plasma treatment in order to improve the adhesion with the coating layer 6 made of a polyphenylene ether organic material. And it is preferable to roughen so that the centerline surface roughness Ra of the surface may become a value of 0.05-5 micrometers. The center line surface roughness Ra is preferably 0.05 μm or more from the viewpoint of preventing peeling between the liquid crystal polymer layer 5 and the coating layer 6 at the time of solder reflow, and when the coating layer 6 is formed on the surface. From the viewpoint of preventing air entrapment, it is preferably 5 μm or less. Therefore, the liquid crystal polymer layer 5 preferably has a rough surface with a centerline surface roughness Ra of 0.05 to 5 μm.

  Next, the coating layer 6 made of a polyphenylene ether-based organic material formed on the surface of the liquid crystal polymer layer 5 has a function of an adhesive when the wiring conductor 2 is formed on the insulating layer 1, and Serves as an adhesive when laminating.

  The coating layer 6 contains 30 to 90% by volume of a polyphenylene ether resin or a derivative thereof, or a polyphenylene ether-based organic material such as a polymer alloy thereof, and particularly from the viewpoint of thermal cycle reliability and positional accuracy during lamination. It is preferable to contain thermosetting polyphenylene ether such as allyl-modified polyphenylene ether.

  If the content of the polyphenylene ether-based organic substance is less than 30% by volume, the kneadability with the filler described later tends to be reduced. If the content exceeds 90% by volume, the surface of the liquid crystal polymer layer 5 is covered with a coating layer. When forming 6, the thickness variation of the coating layer 6 tends to increase. Therefore, the content of the polyphenylene ether organic material is preferably in the range of 30 to 90% by volume.

  The coating layer 6 made of a polyphenylene ether-based organic substance has 2 functional groups capable of 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 additives such as polyfunctional monomers or polyfunctional polymers having at least one, for example, it is preferable to contain triallyl cyanurate, triallyl isocyanurate, and polymers thereof.

  Further, the coating layer 6 is a rubber component for adjusting the elastic modulus, an antioxidant for improving the thermal stability, a light stabilizer such as an ultraviolet absorber for improving the light resistance, and improving the flame retardancy. Halogen-based or phosphoric acid-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, Lubricants such as higher fatty acid metal salts, fluorocarbon surfactants, aluminum oxide, silicon oxide, titanium oxide, barium oxide, strontium oxide, zirconium oxide, calcium oxide for adjusting thermal expansion coefficient and improving mechanical strength Zeolite, silicon nitride, aluminum nitride, silicon carbide, potassium titanate, barium titanate, strontium titanate, calcium titanate Silane coupling agents to improve the bondability and mechanical strength of fillers such as um, aluminum borate, barium stannate, barium zirconate, strontium zirconate, etc. Or a coupling agent such as a titanate coupling agent.

  In particular, when laminating and pressing the insulating layer 1, the covering layer 6 is used as a filler from the viewpoint of suppressing the fluidity of the covering layer 6 and preventing the displacement of the through conductor 3 and the thickness variation of the covering layer 6. It is preferable to contain 10% by volume or more of inorganic insulating powder. Further, from the viewpoint of preventing peeling at the time of 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 is preferably 70% by volume or less. Therefore, it is preferable to contain 10 to 70% by volume of the filler in the coating layer 6 made of polyphenylene ether organic material.

  In addition, the shape of the 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 diameter is about 0.1 to 15 μm and is smaller than the thickness of the coating layer 6.

  According to the multilayer wiring board 4 of the present invention, since the dielectric constants of the liquid crystal polymer layer 5 and the coating layer 6 made of polyphenylene ether-based organic substance are substantially equal, even in the case of slight thickness variations during lamination, The multilayer wiring board 4 having excellent high-frequency transmission characteristics without causing deterioration of transmission characteristics can be obtained. In addition, since the covering layer 6 exhibits the same degree of hydrophobicity as the liquid crystal polymer layer 5, the familiarity between the resins is good, so that the adhesiveness is excellent, and the covering layer 6 has a random molecular structure and is relatively easily moved by heat. Since it is composed of molecules, it can enter into the fine recesses on the surface of the liquid crystal polymer layer 5 and exert a sufficient anchor effect. As a result, the adhesion between the liquid crystal polymer layer 5 and the coating layer 6 is improved, and insulation is performed in a high temperature bias test. The multilayer wiring board 4 having excellent heat resistance and insulation without causing defects can be obtained.

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

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

  In addition, a wiring conductor 2 is formed on the insulating layer 1 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 and gold. The electronic component 7 mounted on the multilayer wiring board 4 is electrically connected to an external electric circuit (not shown). It has a function to connect to.

  Such a wiring conductor 2 has at least the surface of the wiring conductor 2 and the coating layer 6 in the covering layer 6 from the viewpoint of preventing voids from being generated around the wiring conductor 2 when the insulating layer 1 is laminated in a plurality of layers. It is preferably embedded so that the surface thereof is flat. Further, when the wiring conductor 2 is embedded in the coating layer 6, if the porosity of the coating layer 6 in the dry state is 3 to 40% by volume, the resin swell of the coating layer 6 around the wiring conductor 2 does not occur. In addition to being able to flatten, it is possible to easily discharge the air sandwiched between the wiring conductor 2 and the covering layer 6 and prevent entrainment of bubbles. When the porosity in the dry state exceeds 40% by volume, after the insulating layer 1 laminated in plural layers is pressurized and heat-cured, pores remain in the coating layer 6, and the pores remove moisture in the air. Since it may be adsorbed and the insulating property may be lowered, the porosity of the coating layer 6 in the dry state is preferably set in the range of 3 to 40% by volume.

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

  Moreover, it is preferable to make the thickness of the coating layer 6 located between the wiring conductor 2 and the liquid crystal polymer layer 5 into a thickness of 3 to 35 μm. The thickness of the coating layer 6 positioned between the wiring conductor 2 and the liquid crystal polymer layer 5 is set to 3 to 35 μm, and the wiring conductor 2 and the liquid crystal polymer layer 5 having a low dielectric loss tangent are brought close to each other, whereby the dielectric around the wiring conductor 2 is increased. The tangent can be lowered, and as a result, transmission characteristics in a high frequency region, particularly in a frequency region of 100 MHz or higher can be improved. If the thickness of the coating layer 6 is less than 3 μm, the stress generated by the thermal expansion / contraction of the wiring conductor 2 cannot be effectively reduced by the coating layer 6, and cracks are generated from the corners of the wiring conductor 2. When the thickness exceeds 35 μm, the effect of lowering the dielectric loss tangent around the wiring conductor 2 tends to be reduced. Therefore, it is preferable to set the thickness of the coating layer 6 located between the wiring conductor 2 and the liquid crystal polymer layer 5 in the range of 3 to 35 μm.

  Furthermore, the cross-sectional shape in the width direction of the wiring conductor 2 disposed in the insulating layer 1 is a trapezoid whose base side on the insulating layer 1 side is shorter than the opposing base side, and The angle formed between the bottom side and the side side is preferably 95 to 150 °. The cross-sectional shape in the width direction of the wiring conductor 2 disposed in the insulating layer 1 is a trapezoid in which the length of the base on the insulating layer 1 side is shorter than the length of the opposing base, and the base on the insulating layer 1 side By setting the angle formed with the side to 95 to 150 °, the wiring conductor 2 can be easily embedded in the covering layer 6 when the wiring conductor 2 is embedded in the covering layer 6. From the viewpoint of embedding without entrapment of bubbles, it is preferable that the angle formed between the bottom and the side on the insulating layer 1 side is 95 ° or more, and from the viewpoint of miniaturizing the wiring conductor 2. It is preferable to set it to 0 ° or less.

  In addition, the thickness x (μm) of the covering layer 6 positioned between the short base of the wiring conductor 2 and the liquid crystal polymer layer 5 between the insulating layers 1 determines the distance between the upper and lower liquid crystal polymer layers 5. When T (μm) and the thickness of the wiring conductor 2 are t (μm), 3 μm ≦ 0.5 T−t ≦ x ≦ 0.5 T ≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦ 32 μm). It is preferable.

  When the distance between the liquid crystal polymer layers 6 is T (μm) and the thickness of the wiring conductor 2 is t (μm), the wiring conductor 2 is made of a polyphenylene ether organic material between the short bottom of the wiring conductor 2 and the liquid crystal polymer layer 5. By setting the thickness x (μm) of the covering layer 6 to 3 μm ≦ 0.5 T−t ≦ x ≦ 0.5 T ≦ 35 μm, the distance between the short bottom of the wiring conductor 2 and the liquid crystal polymer layer 5 and the wiring conductor 2 The difference in distance between the long base and the adjacent liquid crystal polymer layer 5 can be reduced to less than t (μm), and the dielectric tangent variation around the wiring conductor 2 can be reduced. It can be prevented from decreasing. Therefore, the thickness x (μm) of the coating layer 6 made of a polyphenylene ether-based organic material, which is located between the trapezoidal upper bottom surface of the wiring conductor 2 and the liquid crystal polymer layer 5, and the distance between the liquid crystal polymer layers 6 as T (Μm) When the thickness of the wiring conductor 2 is t (μm), the range of 3 μm ≦ 0.5 T−t ≦ x ≦ 0.5 T ≦ 35 μm is preferable.

  Such a wiring conductor 2 is formed by depositing, for example, a metal foil made of copper, which is patterned by a subtractive method using a known photoresist, on the precursor sheet to be the insulating layer 1 by a transfer method or the like. Is done. First, a metal foil transfer film in which a metal foil made of copper is bonded to a support film with an adhesive is prepared, and then the metal foil on the film is subtractive using a known photoresist. Is used to etch into a pattern. At this time, the side surface on the surface side of the pattern is easily etched because it takes a longer time to contact the etching solution than the side surface on the film side, and the cross-sectional shape in the width direction of the pattern can be trapezoidal. The trapezoidal shape can be a trapezoid whose angle between the short base and the side is 95 to 150 ° by adjusting the concentration of the etching solution and the etching time. And this metal foil transfer film is laminated | stacked on the precursor sheet | seat used as the insulating layer 1, and it becomes a support body after hot-pressing for 10 minutes to 1 hour on the conditions whose temperature is 100-200 degreeC and a pressure is 0.5-10 MPa. The wiring conductor 2 in which the upper base side of the trapezoidal shape is embedded in the coating layer 6 made of a polyphenylene ether-based organic material is formed by peeling and removing the film and transferring the metal foil to the surface of the precursor sheet to be the insulating layer 1 Can do.

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

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

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

  In such a multilayer wiring board 4, the through conductor 3 is formed at a desired position of the precursor sheet to be the insulating layer 1 manufactured by the method as described above, and then the patterned metal foil of copper, for example, is heated. It is transferred by hot pressing for 10 minutes to 1 hour at 100 to 200 ° C. under a pressure of 0.5 to 10 MPa, and these are laminated and finally 30 minutes under a temperature of 150 to 300 ° C. and a pressure of 0.5 to 10 MPa. Manufactured by hot pressing for 24 hours to complete curing.

  Thus, according to the multilayer wiring board 4 of the present invention, since the insulating layer 1 has the coating layer 6 made of polyphenylene ether-based organic material on the surface of the liquid crystal polymer layer 5, it has excellent high frequency transmission characteristics and moisture resistance. -It can be set as the multilayer wiring board 4 excellent in solder heat resistance and insulation.

  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 gist of the present invention. For example, in the above-described embodiment, four layers are possible. The multilayer wiring board 4 is manufactured by laminating the insulating layers 1, but the multilayer wiring board 4 may be fabricated by laminating two, three, or five or more insulating layers 1. In addition, a build-up layer or a solder resist layer made of an insulating layer mainly composed of one, two, or three or more organic resins may be formed on the upper and lower surfaces of the multilayer wiring board 4 of the present invention.

  Next, the multilayer wiring board of the present invention was evaluated by producing the following samples.

(Example) First, spherical fused silica having an average particle size of 0.6 μm is added to a thermosetting polyphenylene ether resin so that the content thereof becomes 40% by volume, and toluene as a solvent is further promoted to cure organic resin. The catalyst for adding was added and mixed for 1 hour to prepare a varnish.

  Next, plasma treatment is performed on the surface of the liquid crystal polymer layer having a melting point of 320 ° C. to prepare a liquid crystal polymer layer having a thickness of 35 μm and a centerline surface roughness Ra of 0.10 μm. The varnish is applied to the upper surface of the liquid crystal polymer layer. It was applied by a doctor blade method to form a dried thermosetting polyphenylene ether coating layer having a thickness of about 20 μm. And the polyphenylene ether coating layer was similarly shape | molded also to the lower surface of this liquid crystal polymer layer, and the precursor sheet | seat used as an insulating layer was manufactured.

  Further, a through-hole having a diameter of 65 μm was formed in this precursor sheet by a CO2 laser, and a through-conductor was formed by embedding a conductive paste containing copper powder and an organic binder in the through-hole by screen printing.

  Next, a transfer support film with a 12 μm thick copper foil formed in a circuit shape and a precursor sheet serving as an insulating layer on which a through conductor is formed are aligned with a pressure of 3 MPa by a vacuum laminator. After pressurizing for 30 seconds, 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 were formed were stacked and heat-treated at a temperature of 200 ° C. for 5 hours under a pressure of 3 MPa to be completely cured to obtain a multilayer wiring board.

  In addition, the test board for evaluating insulation is a test board for forming a comb-like pattern wiring conductor with a wiring width of 50 μm and a wiring interval of 50 μm in a multilayer wiring board, and for evaluating transmission characteristics. Has formed a wiring conductor having a stripline structure inside a multilayer wiring board.

  (Comparative Example 1) The multilayer wiring board used for Comparative Example 1 was formed by first forming a circuit-like wiring conductor using a photoresist on a liquid crystal polymer layer having a melting point of 320 ° C. with a copper foil bonded to the surface by heat melting. Next, a through hole having a diameter of 65 μm was formed by a CO2 laser, and a through conductor was formed by embedding a conductive paste containing copper powder and an organic binder in the through hole by screen printing, thereby creating a circuit board. Thereafter, these circuit boards were manufactured by hot pressing at a temperature of 285 ° C. for 5 minutes under a pressure of 1 MPa with a liquid crystal polymer layer having a melting point of 280 ° C. therebetween.

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

  The insulation was evaluated by performing a high-temperature bias test with an applied voltage of 5.5 V under the conditions of a temperature of 130 ° C. and a relative humidity of 85%, measuring the insulation resistance between the wiring conductors after 168 hours, and before and after the test. Evaluation was made by comparing the amount of change. 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 insulation evaluation results, and Table 2 shows the transmission characteristic evaluation results.

From Table 1, it was found that the multilayer wiring board of Comparative Example 1 had a low insulation resistance of 3.5 × 10 ⁶ Ω after the high temperature bias test and was inferior in heat resistance. Further, from Table 2, it was found that the multilayer wiring board of Comparative Example 2 deteriorated to have a transmission characteristic of −1.0 dB or less in a high frequency region of 20 GHz or higher, and inferior to the high frequency transmission characteristics.

In contrast, the multilayer wiring board of the present invention has an excellent insulation resistance of 4.3 × 10 ¹⁰ Ω even after a high-temperature bias test, and a transmission characteristic as low as −0.51 dB even in a high frequency region of 40 GHz. It was.

It is sectional drawing which shows an example of embodiment of the hybrid integrated circuit formed by mounting a semiconductor element on the multilayer wiring board of this invention. It is principal part sectional drawing of the multilayer wiring board of this invention.

Explanation of symbols

DESCRIPTION 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 T made of organic organic material: distance t between liquid crystal polymer layers: thickness of wiring conductor x: between the upper bottom surface of the trapezoidal wiring conductor and the liquid crystal polymer layer The thickness of the coating layer made of polyphenylene ether organic material

Claims (7)

A plurality of insulating layers made of an organic material and laminated with wiring conductors made of metal foil on at least one of the upper and lower surfaces, and between the wiring conductors positioned above and below the insulating layer A multilayer wiring board electrically connected through a through conductor formed in the insulating layer, wherein the insulating layer is a coating layer made of a polyphenylene ether-based organic material on the upper and lower surfaces of a liquid crystal polymer layer whose surface is plasma-treated. A multilayer wiring board characterized by comprising: 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 [mu] m. The multilayer wiring board according to claim 1, wherein the 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 material is a thermosetting polyphenylene ether. The multilayer wiring board according to any one of claims 1 to 4, wherein a thickness of the coating layer located between the liquid crystal polymer layer and the wiring conductor is 3 to 35 µm. The cross-sectional shape in the width direction of the wiring conductor disposed in the insulating layer is a trapezoid in which the length of the base on the insulating layer side is shorter than the length of the opposing base, and the base on the insulating layer side 6. The multilayer wiring board according to claim 1, wherein an angle formed with the side is 95 to 150 degrees. Between the insulating layers, the thickness x (μm) of the coating layer located between the bottom of the wiring conductor having a short length and the liquid crystal polymer layer indicates that the distance between the upper and lower liquid crystal polymer layers is T (μm). ) When the thickness of the wiring conductor is t (μm), 3 μm ≦ 0.5 T−t ≦ x ≦ 0.5 T ≦ 35 μm (however, 8 μm ≦ T ≦ 70 μm, 1 μm ≦ t ≦ 32 μm) The multilayer wiring board according to claim 6.

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