JP4272767B2 - Thermally conductive molded body and method for producing the same, resin substrate for conductor circuit and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermally conductive molded article having good thermal conductivity, a method for producing the same, and a resin substrate for conductor circuits.
[0002]
[Prior art]
In recent years, countermeasures against heat generated by electronic devices have become very important issues due to high-density mounting of semiconductor packages, high integration of LSIs, and high speeds associated with high performance, miniaturization, and weight reduction of electronic devices. ing. Usually, in order to diffuse the heat of the element that generates heat, a method using a printed wiring board made of a metal or ceramic having good thermal conductivity, a method of forming a thermal via hole in the board to dissipate heat, or heat as a semiconductor package material Use of highly conductive metal, ceramics or resin, grease with high thermal conductivity or flexible heat conduction to reduce contact thermal resistance between heat source and radiator or between heat source and metal heat transfer plate A method of interposing a functional rubber material, a method of using a cooling fan, a heat pipe, a heat diffusion plate, and the like have been implemented.
[0003]
Conventional resin substrates used for wiring boards for mounting electronic components such as semiconductor packages, ie glass cloth epoxy substrates, have mechanical properties, dimensional accuracy, and through-hole processability compared to other metal substrates and ceramic substrates. Although multi-layering and the like are relatively good, one disadvantage is that the thermal conductivity is inferior.
[0004]
Therefore, resin substrates that require high thermal conductivity include metal oxides such as aluminum oxide, boron nitride, aluminum nitride, magnesium oxide, zinc oxide, silicon carbide, quartz, and aluminum hydroxide, which have high thermal conductivity in the resin. A method of filling an electrically insulating filler such as a metal, a metal nitride, a metal carbide, or a metal hydroxide has been studied, but sufficient thermal conductivity has not been obtained.
[0005]
[Problems to be solved by the invention]
According to Japanese Patent Laid-Open No. 9-255871, a thermoplastic resin composition and a molded product containing polybenzazole short fibers are proposed. The present invention is a hard resin composition having impact resistance, toughness, electrical insulation and thermal conductivity, and molded articles such as a substrate material and a case material. However, since this molded article is obtained by randomly dispersing polybenzazole short fibers, it does not take advantage of the large thermal conductivity in the fiber direction, which is a feature of polybenzazole short fibers. Therefore, even when polybenzazole short fibers are added in a large amount, the thermal conductivity of the obtained molded product has not been improved so much.
[0006]
In addition, the thermosetting resin composition containing the polybenzazole short fibers of Japanese Patent Application No. 11-166089 and the heat conductive molded product using the same of the present applicant also have polybenzazole short fibers dispersed randomly. Similarly, the large thermal conductivity in the fiber direction of the polybenzazole short fibers could not be fully utilized.
[0007]
On the other hand, Japanese Patent Application Laid-Open No. 11-17369 is a heat dissipating material made of a synthetic resin wire having a constant diameter in which organic fibers are disposed in a synthetic resin in the length direction of the resin. This heat dissipating material is a synthetic resin wire having a diameter of 5 mm or less and a length of 4 mm or more made of a pultrusion rod, and obtains a heat conductive molded body and a conductor circuit resin substrate which are the object of the present invention. I can't.
[0008]
According to Japanese Patent Application No. 11-79228 filed by the applicant of the present application, although a thermally conductive molded product such as a plate shape that was not obtained in Japanese Patent Application Laid-Open No. 11-17369 can be produced, polybenzazole long fibers are polymerized. Since they are arranged in the form of long fibers therein, it is a problem that it is difficult to perform a subsequent cutting process.
[0009]
In Japanese Patent Application No. 11-87483 by the present applicant, a diamagnetic filler having a thermal conductivity of 20 W / m · K or more is oriented in a certain direction in the polymer. Polybenzazole staple fibers were not considered as targets.
[0010]
[Means for Solving the Problems]
As a result of diligent studies to solve these problems, a thermally conductive molded body characterized in that polybenzazole short fibers are oriented in a certain direction in a polymer has anisotropy in thermal conductivity. We have found a method for manufacturing a thermally conductive molded body that can be easily manufactured by applying the fact that it has excellent thermal conductivity and that polybenzazole short fibers have the property of being oriented along magnetic field lines in a magnetic field. The present invention has been reached.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
That is, the present invention relates to a thermally conductive molded product characterized in that polybenzazole short fibers are oriented in a certain direction in a polymer, and further to applying a magnetic field to a polymer composition containing polybenzazole short fibers. A method for producing a thermally conductive molded article characterized by solidifying a polybenzazole short fiber in a composition after being applied in a certain direction, and a magnetic orientation of the polybenzazole short fiber in the thickness direction It is a resin substrate for a conductor circuit.
[0012]
The polybenzazole short fiber used in the present invention is a short fiber composed of a polybenzazole polymer. Polybenzazole (PBZ) is a polybenzoxazole homopolymer (PBO), a polybenzothiazole homopolymer (PBT). ) And their PBO, PBT random copolymer, sequential copolymer, block copolymer or graft copolymer. Although the diameter, cross-sectional shape and the like of the polybenzazole short fiber are not specified, the length of the polybenzazole short fiber is preferably 3 mm or less. Use of short polybenzazole fibers longer than 3 mm is not preferable because it is difficult to uniformly disperse in the polymer and the viscosity of the composition is increased to deteriorate the moldability. More preferably, the length of the polybenzazole short fiber is 2 mm or less, more preferably 1 mm or less, and still more preferably 0.5 mm or less.
[0013]
The amount of the polybenzazole short fiber contained in the polymer is preferably 0.1 to 50 parts by weight with respect to 100 parts by weight of the polymer. If the amount is less than 0.1 part by weight, the effect of improving the thermal conductivity is small. If the amount exceeds 50 parts by weight, the viscosity of the composition increases, the fluidity is impaired, and the molding process becomes difficult, and air bubbles It is unsuitable because it is unavoidable. The addition amount of the polybenzazole short fiber is more preferably 0.5 to 30 parts by weight, and further preferably 1 to 20 parts by weight.
[0014]
Polybenzazole short fibers can be produced by a method of cutting polybenzazole long fibers into a certain length, and a commercially available product (trade name = Zylon, manufactured by Toyobo Co., Ltd.) can be easily obtained. it can. The tensile strength of the polybenzazole short fiber is preferably 4 GPa or more and the initial tensile elastic modulus is 140 GPa or more. By using polybenzazole short fibers whose tensile strength and initial tensile elastic modulus are within this range, the thermally conductive molded product and the resin circuit board for conductor circuits of the present invention exhibit higher thermal conductivity and its anisotropy. can do.
[0015]
In addition, as fibers other than polybenzazole short fibers, a small amount of organic fibers such as aramid fibers, polyester fibers, aliphatic polyamide fibers, vinylon fibers, natural fibers, carbon fibers, metal fibers, and composite fibers obtained by combining these fibers It is also possible to mix short fibers and long fibers made of or a small amount of woven or non-woven fabrics.
[0016]
The kind of polymer used in the present invention is not particularly limited. Thermoplastic resin, thermoplastic elastomer, heat depending on required performance such as hardness, thermal conductivity, mechanical strength, heat resistance, electrical characteristics, durability, reliability, etc. A curable resin, a crosslinked rubber, or the like can be selected. As a polymer used as a raw material for filling polybenzazole short fibers at a high concentration, a liquid material or a polymer having a low viscosity in a molten state is preferable. Further, by dissolving the polymer with a solvent to lower the viscosity, the concentration of the polybenzazole short fibers can be increased, or the orientation in a magnetic field atmosphere can be promoted.
[0017]
Examples of thermoplastic resins and thermoplastic elastomers used as polymers include ethylene α-olefin copolymers such as polyethylene, polypropylene, and ethylene propylene copolymers, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, and ethylene. Vinyl acetate copolymer, polyvinyl alcohol, polyvinyl acetal, fluororesin such as polyvinylidene fluoride and polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polyacrylonitrile, styrene acrylonitrile copolymer, ABS resin, Polyphenylene ether and modified PPE resin, aliphatic and aromatic polyamides, polyimide, polyamideimide, polymethacrylic acid and its methyl Polymethacrylates such as stealth, polyacrylic acids, polycarbonate, polyphenylene sulfide, polysulfone, polyethersulfone, polyethernitrile, polyetherketone, polyketone, liquid crystal polymer, silicone resin, ionomer and other thermoplastic resins, styrene butadiene Or styrene isoprene block copolymer and its hydrogenated polymer and styrene thermoplastic elastomer, olefin thermoplastic elastomer, vinyl chloride thermoplastic elastomer, polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, etc. These thermoplastic elastomers can be mentioned.
[0018]
Thermosetting resins and cross-linked rubbers include epoxy resins, polyimide resins, bismaleimide resins, benzocyclobutene resins, phenol resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, urethane resins, polyimide silicone resins, and thermosetting types. Polyphenylene ether and modified PPE resin, natural rubber, butadiene rubber, isoprene rubber, styrene butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber and halogenated Examples thereof include cross-linked rubbers such as butyl rubber, fluoro rubber, urethane rubber, and silicone rubber.
[0019]
Among these polymers, the thermally conductive molded body of the present invention is composed of silicone rubber, epoxy resin, urethane resin, unsaturated polyester resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, fluorine resin, and polyphenylene ether resin. It is preferable to use at least one selected polymer from the viewpoints of heat resistance and electrical reliability.
[0020]
Furthermore, these polymers can be made into a low-viscosity liquid when mixing polybenzazole short fibers, or a low viscosity when heated and melted, and when polybenzazole short fibers are applied when a magnetic field is applied. Easy to align. Fluorine resin, thermosetting polyphenylene ether resin, modified PPE resin, and polyolefin resin are preferable for wiring board applications that require low dielectric constant and dielectric loss tangent and characteristics in a high frequency range. Further, a polymer alloy composed of a plurality of polymers selected from these polymers may be used. In addition, the crosslinking method for the crosslinkable polymer is not limited to thermosetting, and a polymer obtained by a known crosslinking method such as photocuring property or moisture curing property can be used.
[0021]
In addition to the metal oxide, metal nitride, such as aluminum oxide, boron nitride, aluminum nitride, zinc oxide, silicon carbide, and aluminum hydroxide having high thermal conductivity as the heat conductive filler of the present invention. A small amount of fillers such as spheres, powders, fibers, needles, scales, whiskers and the like made of metals and alloys such as metal, metal carbides and metal hydroxides may be used together.
[0022]
Examples of methods for orienting polybenzazole short fibers in a polymer in a certain direction include a method using a flow field or a shear field, a method using a magnetic field, and a method using an electric field. By any method, the polybenzazole short fibers can be oriented in a certain direction in the polymer, and the thermally conductive molded article of the present invention can be obtained. However, in the present invention, the method of orienting the polybenzazole short fiber by applying the magnetic field using the anisotropy of the magnetic susceptibility of the polybenzazole short fiber, in particular, orienting the polybenzazole short fiber in an arbitrary direction. Therefore, it is suitable as a method for producing a heat conductive molded article having excellent heat conductivity and its anisotropy. Note that the present inventors have reported that the anisotropic magnetic susceptibility χ of polybenzazole fiber (Zylon HM manufactured by Toyobo Co., Ltd.) _a Was measured with a magnetic anisotropy torque meter (Tamagawa Seisakusho Co., Ltd.), 6.1 × 10 ^-7 Met.
[0023]
That is, by applying a magnetic field to a polymer composition containing polybenzazole short fibers, the polybenzazole short fibers in the composition are oriented in a certain direction and solidified, thereby producing the thermally conductive molded article of the present invention. It is the feature.
[0024]
Applying a magnetic field from the outside to orient the polybenzazole short fibers in the polymer composition in a certain direction along the lines of magnetic force, taking advantage of the high thermal conductivity in the fiber direction of the oriented polybenzazole short fibers, and heat in a certain direction It is possible to obtain a thermally conductive molded body with significantly improved conductivity.
[0025]
For example, in order to align and align polybenzazole short fibers in the thickness direction of a plate-like thermally conductive molded body, the N and S poles of permanent magnets and electromagnets face each other in the thickness direction, and the direction of the lines of magnetic force is desired. It is installed so as to correspond to the orientation direction of benzazole short fibers. On the other hand, in the case where the thermal conductivity in a certain direction is improved in the longitudinal direction and the transverse direction or the longitudinal and transverse horizontal directions in the plane of the plate-like thermally conductive molded body, the N of the magnet is perpendicular to the thickness direction. If the pole and the S pole are opposed, the polybenzazole short fibers can be aligned in the in-plane direction. Alternatively, the polybenzazole short fibers can be aligned in the in-plane direction even when the N-pole and N-pole of the magnet or the S-pole and S-pole are opposed to each other in the thickness direction.
[0026]
Further, the lines of magnetic force are not necessarily linear, but may be curved, rectangular, or two or more directions. That is, it is possible to orient the polybenzazole short fibers in an arbitrary fixed direction to impart thermal conductivity anisotropy. Further, the magnets do not necessarily have to be opposed to both sides, and the polybenzazole short fibers in the raw material composition can be oriented by a magnet arranged only on one side.
[0027]
The magnetic field generating means used as the external magnetic field may be a permanent magnet, an electromagnet, or a coil, but a practical polybenzazole short fiber orientation can be achieved when the magnetic flux density is in the range of 0.05 Tesla to 30 Tesla. In addition, since the present invention utilizes the very weak anisotropic magnetic susceptibility of the polybenzazole short fibers, the polybenzazole short fibers can be sufficiently oriented in a stronger magnetic field atmosphere before being subjected to a thermosetting reaction or cooling. It is necessary to solidify the matrix polymer. A preferred magnetic flux density that is easily oriented is 0.5 Tesla or more, more preferably 1 Tesla or more.
[0028]
In order to improve the wettability and adhesion between the polybenzazole short fibers and the polymer, the surface of the polybenzazole short fibers is previously degreased and washed, UV irradiation treatment, corona discharge treatment, plasma treatment, flame treatment It is preferable to perform an activation treatment such as ion implantation. Furthermore, by treating with a normal coupling agent such as silane, titanium, or aluminum after these surface treatments, it becomes easier to disperse and mix a larger amount of polybenzazole short fibers, and the resulting molded product Higher thermal conductivity can be achieved.
[0029]
The heat conductive molded body of the present invention can be applied to a heat radiating plate, a wiring board, a heat radiating rubber sheet, a semiconductor package component, a heat sink, a heat spreader, a housing, and the like that require high heat conductivity.
[0030]
The resin substrate for a conductor circuit according to the present invention is characterized in that polybenzazole short fibers are magnetically oriented in the thickness direction of the substrate. As a method of forming a conductor circuit on this substrate, a method of forming a circuit by bonding a substrate and a conductor foil, a method of bonding a conductor circuit on which a circuit has been formed in advance to a substrate, or forming a conductor circuit directly by printing, etc. It can obtain by well-known methods, such as the method of doing.
[0031]
Since the polybenzazole short fiber has excellent electrical insulation, and the resin substrate used for the wiring board of the present invention also has good electrical insulation, the adhesive used when laminating the conductor circuits is known electrical insulation. May be used. When a heat conductive filler such as aluminum oxide or nitrogen boron is added to the adhesive, the heat dissipation characteristics are further improved.
[0032]
8 to 11 show examples in which a plate-like thermally conductive molded body obtained by the present invention is interposed between a semiconductor element that generates heat and a radiator, a wiring board, a heat sink, a housing, and the like that are heat transfer members. It is. FIG. 8 shows an example in which the thermally conductive molded body 1 of the present invention is disposed in the gap between the ball grid array type semiconductor package 8a and the radiator 9, and the conductor circuit resin substrate 7 of the present invention is used.
[0033]
FIG. 9 shows an example in which the thermally conductive molded body 1 of the present invention is disposed in the gap between the chip size semiconductor package 8b and the conductor circuit resin substrate 7.
[0034]
FIG. 10 shows an example in which the thermally conductive molded body 1 of the present invention is disposed in the gap between the pin grid array type semiconductor package 8c and the heat sink 10, and the conductor circuit resin substrate 7 of the present invention is used.
[0035]
FIG. 11 shows an example in which the thermally conductive molded body 1 of the present invention is disposed in a gap between a plurality of semiconductor elements 11 that generate heat and a housing 12, and the conductor circuit resin substrate 7 of the present invention is used.
[0036]
Hereinafter, the present invention will be described in more detail based on examples. In addition, the thermal conductivity of a following example and a comparative example is the value calculated by measuring with a laser flash type thermal conductivity meter (TC-7000 manufactured by Vacuum Riko Co., Ltd.).
[0037]
Comparative Example 1 and Comparative Example 2 are conventional molded bodies in which polybenzazole short fibers are filled in a polymer without orientation, and the thermal conductivity is small. Examples 1 to 1 of the present invention Example 7 The heat conductive molded body is a heat conductive molded body obtained by applying a magnetic field to a polymer composition containing polybenzazole short fibers and orienting the polybenzazole short fibers in the composition in a certain direction to solidify, There is a feature that the thermal conductivity in the direction of the oriented fibers is large. Example 8 Is an example of the conductor circuit resin substrate of the present invention, and has a smaller thermal resistance and better heat dissipation characteristics than the wiring substrate of Comparative Example 3.
[0038]
[Example 1]
100 parts by weight of unsaturated polyester resin (Eporac G157 manufactured by Nippon Shokubai Co., Ltd.) and 5 parts by weight of polybenzazole short fiber (Zylon HM manufactured by Toyobo Co., Ltd .: diameter 11 μm, length 0.5 mm) are mixed and vacuum defoamed. Composition a was prepared. An aluminum plate having a thickness of 1.5 mm, a length of 20 mm, and a width of 20 mm is filled with the composition a, and the thickness is as shown in FIGS. 4 (1), 4 (2), and 4 (3). In a magnetic field atmosphere in which the N pole and S pole with a magnetic flux density of 6 Tesla face each other, the polybenzazole short fibers were sufficiently oriented and then heat cured to obtain a plate-like thermally conductive molded body. The thermal conductivity in the thickness direction and in-plane direction of the obtained heat conductive molded body was 2.5 W / m · K and 0.3 W / m · K, respectively. The polybenzazole short fibers of the thermally conductive molded body were aligned in the thickness direction as shown in FIG.
[0039]
[Example 2]
The composition a prepared in the same manner as in Example 1 was filled in a plate-shaped mold made of aluminum having a thickness of 1.5 mm, a length of 20 mm, and a width of 20 mm, and FIG. 5 (1), FIG. 5 (2), FIG. 3) As shown in 3), the polybenzazole short fibers are sufficiently oriented in a magnetic field atmosphere with a magnetic flux density of 6 Tesla in which the N and S poles of the magnet face each other in the direction perpendicular to the thickness direction, and are then heat-cured and plate The heat conductive molded object of this was obtained.
The thermal conductivity in the thickness direction, in-plane X direction, and in-plane Y direction of the obtained heat conductive molded body was 0.3 W / m · K, 2.2 W / m · K, and 0.4 W / m · K, respectively. Met. The polybenzazole short fibers of the thermally conductive molded body were aligned in the in-plane direction as shown in FIG.
[0040]
[Example 3]
Composition 100 b by mixing 100 parts by weight of a liquid epoxy resin (TB2280C manufactured by ThreeBond Co., Ltd.) and 3 parts by weight of polybenzazole short fibers (Zylon HM manufactured by Toyobo Co., Ltd .: diameter 11 μm, length 1 mm) Was prepared. The composition b is filled in a plate-shaped mold made of aluminum having a thickness of 3 mm, a length of 20 mm, and a width of 20 mm, and is arranged in the thickness direction as shown in FIGS. 4 (1), 4 (2), and 4 (3). The polybenzazole short fibers were sufficiently oriented in a magnetic field atmosphere with a magnetic flux density of 10 Tesla facing the north and south poles, and then cured by heating to obtain a plate-like thermally conductive molded body. The thermal conductivity in the thickness direction and in-plane direction of the obtained heat conductive molded body was 1.1 W / m · K and 0.3 W / m · K, respectively. The polybenzazole short fibers of the thermally conductive molded body were aligned in the thickness direction as shown in FIG.
[0041]
[Example 4]
The composition b prepared in the same manner as in Example 3 was filled in a plate-shaped mold made of aluminum having a thickness of 3 mm, a length of 20 mm, and a width of 20 mm, and FIG. 5 (1), FIG. 5 (2), FIG. ), The polybenzazole short fibers are sufficiently oriented in a magnetic field atmosphere having a magnetic flux density of 10 Tesla in which the N and S poles of the magnet face each other in the direction perpendicular to the thickness direction, and then heat-cured to obtain a plate-like shape. A thermally conductive molded body was obtained. The thermal conductivity in the thickness direction, in-plane X direction, and in-plane Y direction of the obtained heat conductive molded body was 0.3 W / m · K, 1.2 W / m · K, and 0.3 W / m · K, respectively. It was. The polybenzazole short fibers of the thermally conductive molded body were aligned in the in-plane direction as shown in FIG.
[0042]
[Example 5]
100 parts by weight of liquid silicone rubber (GE Toshiba Silicone Co., Ltd. TSE3070), 20 parts by weight of polybenzazole short fiber (Toyobo Co., Ltd., Zylon HM: diameter 11 μm, length 0.1 mm), aluminum oxide powder (Showa Denko Co., Ltd.) AS-20) 50 parts by weight were mixed and vacuum defoamed composition c was prepared. An aluminum plate having a thickness of 0.5 mm, a length of 20 mm, and a width of 20 mm is filled with the composition c, and the thickness direction is as shown in FIGS. 4 (1), 4 (2), and 4 (3). The polybenzazole short fibers were sufficiently oriented in a magnetic field atmosphere in which the N pole and S pole with a magnetic flux density of 10 Tesla face each other, and then heat-cured to obtain a flexible rubber sheet-like thermally conductive molded body. The thermal conductivity in the thickness direction and in-plane direction of the obtained heat conductive molded body was 4.1 W / m · K and 0.5 W / m · K, respectively. The polybenzazole short fibers of the thermally conductive molded body were aligned in the thickness direction as shown in FIG.
[0043]
[Example 6]
The composition c prepared in the same manner as in Example 1 was filled into a plate-shaped mold made of aluminum having a thickness of 0.5 mm, a length of 20 mm, and a width of 20 mm, and FIG. 5 (1), FIG. 5 (2), FIG. 3) As shown in 3), the polybenzazole short fibers are sufficiently oriented in a magnetic field atmosphere having a magnetic flux density of 10 Tesla in which the N and S poles of the magnet face each other in the direction perpendicular to the thickness direction, and are then heat-cured and flexible. A rubber sheet-like thermally conductive molded body was obtained. The thermal conductivity in the thickness direction, in-plane X direction, and in-plane Y direction of the obtained heat conductive molded body was 0.5 W / m · K, 3.8 W / m · K, and 0.5 W / m · K, respectively. . The polybenzazole short fibers of the thermally conductive molded body were aligned in the in-plane direction as shown in FIG.
[0044]
[Example 7]
To 100 parts by weight of a styrene-based thermoplastic elastomer (Taftec H1053 manufactured by Asahi Kasei Kogyo Co., Ltd.), 2000 parts by weight of toluene as a solvent was added and dissolved. 1 mm) 5 parts by weight were mixed to prepare a solution-like composition d. The composition d is filled in a box-shaped mold made of aluminum with a length of 20 mm, a width of 20 mm, and a depth of 40 mm, as shown in FIGS. 4 (1), 4 (2), and 4 (3). After the polybenzazole short fibers are sufficiently oriented in a magnetic field atmosphere with a magnetic flux density of 6 Tesla facing the north and south poles, the solvent toluene is volatilized and dried by heating to obtain a rubber sheet-like thermally conductive molded body. It was. The thermal conductivity in the thickness direction and in-plane direction of the obtained heat conductive molded body was 1.2 W / m · K and 0.3 W / m · K, respectively. The polybenzazole short fibers of the thermally conductive molded body were aligned in the thickness direction as shown in FIG.
[0045]
[Comparative Example 1]
100 parts by weight of unsaturated polyester resin (Eporac G157 manufactured by Nippon Shokubai Co., Ltd.) and 5 parts by weight of polybenzazole short fibers (Zylon HM manufactured by Toyobo Co., Ltd .: diameter 11 μm, length 0.5 mm) are mixed and vacuum degassed. A composition a was prepared. A plate-like mold made of aluminum having a thickness of 1.5 mm, a length of 20 mm, and a width of 20 mm was filled with the composition a and cured by heating to obtain a plate-like thermally conductive molded body. The thermal conductivity in the thickness direction and in-plane direction of the obtained heat conductive molded body was 0.3 W / m · K and 0.4 W / m · K, respectively. The polybenzazole short fibers of the thermally conductive molded body were not oriented and were randomly dispersed as shown in FIG.
[0046]
[Comparative Example 2]
100 parts by weight of liquid silicone rubber (GE Toshiba Silicone Co., Ltd. TSE3070), 20 parts by weight of polybenzazole short fiber (Toyobo Co., Ltd., Zylon HM: diameter 11 μm, length 0.1 mm), aluminum oxide powder (Showa Denko Co., Ltd.) AS-20) 50 parts by weight were mixed and vacuum defoamed composition c was prepared. The composition c was filled in an aluminum plate having a thickness of 0.5 mm, a length of 20 mm, and a width of 20 mm and cured by heating to obtain a flexible rubber sheet-like thermally conductive molded body. The thermal conductivity in the thickness direction and in-plane direction of the obtained heat conductive molded body was 0.2 W / m · K and 0.3 W / m · K, respectively. The polybenzazole short fibers of the thermally conductive molded body were not oriented and were randomly dispersed as shown in FIG.
[0047]
[Example 8]
After applying an epoxy adhesive to the plate-like thermally conductive molded body obtained in Example 1, a 35 μm copper foil is pressure-bonded with a press, and the copper foil is etched to form a conductor circuit 5. A wiring substrate 6 as shown in FIG. 6 was produced. The transistor (TOSHIBA Corporation TO-220) was soldered and energized while cooling the opposite surface with a cooling fan. The thermal resistance was determined from the temperature difference between the transistor and the conductor circuit resin substrate, and found to be 0.35 ° C / W. It was.
[0048]
[Comparative Example 3]
After applying an epoxy adhesive to the plate-like thermally conductive molded body obtained in Comparative Example 1, a 35 μm copper foil was pressure-bonded with a press, and the copper foil was etched to form a conductor circuit 6. A wiring board 14 as shown in FIG. 7 was produced. The transistor (TOSHIBA Corporation TO-220) was soldered and energized while cooling the opposite surface with a cooling fan. The thermal resistance was determined from the temperature difference between the transistor and the wiring board, and found to be 0.68 ° C./W.
[0049]
【The invention's effect】
According to the method for producing a thermally conductive molded body of the present invention, since the polybenzazole short fibers are oriented and solidified in a certain direction in a polymer, the heat conductivity in the arbitrarily oriented fiber direction is excellent. In addition, it is possible to easily manufacture a thermally conductive molded body. Furthermore, the resin circuit board for conductor circuits of the present invention has a low thermal resistance in that direction because the polybenzazole short fibers are magnetically oriented in the thickness direction of the substrate. Therefore, it is possible to provide a useful electrical product having excellent heat dissipation characteristics when mounting various devices such as a CPU (central processing element), a power source, and a plasma display that generate a large amount of heat.
[Brief description of the drawings]
FIG. 1 is a thermally conductive molded article of the present invention in which polybenzazole short fibers are oriented in the thickness direction.
FIG. 2 is a thermally conductive molded article of the present invention in which polybenzazole short fibers are oriented in the plane direction.
FIG. 3 is an overview diagram showing a dispersion state of polybenzazole short fibers in a conventional molded body.
FIG. 4 is a view showing a method for producing a thermally conductive molded body of the present invention.
FIG. 5 is a view showing another method for producing the thermally conductive molded body of the present invention.
FIG. 6 is a wiring board using the thermally conductive molded body of the present invention.
FIG. 7 is a wiring board using a conventional heat conductive molded body.
FIG. 8 shows an example in which the thermally conductive molded body and the resin substrate for a conductor circuit according to the present invention are used.
FIG. 9 shows an example in which the thermally conductive molded body and the resin substrate for a conductor circuit according to the present invention are used.
FIG. 10 shows an example in which the thermally conductive molded body and the resin substrate for a conductor circuit according to the present invention are used.
FIG. 11 shows an example in which the thermally conductive molded body and the resin substrate for a conductor circuit according to the present invention are used.
[Explanation of symbols]
1 Thermally conductive molded body
2 Polybenzazole staple fiber
3 Mold
4 Magnet
5 Conductor circuit
6 Resin substrate for conductor circuit of the present invention
7 Conductor circuit resin board
8a, 8b, 8c Semiconductor element
9 Heatsink
10 Heat sink
11 Semiconductor elements
12 Case
13 Molded articles containing conventional polybenzazole short fibers
14 Conventional wiring board

Claims (9)

A heat conductive molded body comprising a polymer composition containing polybenzazole short fibers , wherein the polybenzazole short fibers are magnetically oriented in the thickness direction of the plate-shaped molded body.   2. The thermally conductive molded article according to claim 1, wherein the polybenzazole short fibers have a length of 3 mm or less and a content of 0.1 to 50 parts by weight with respect to 100 parts by weight of the polymer. The thermally conductive molded article according to claim 1, wherein the polymer is any one of a thermoplastic resin, a thermoplastic elastomer, a thermosetting resin, and a crosslinked rubber. The thermally conductive molded article according to claim 1, which has a conductor circuit on its upper surface and is used as a substrate . A magnetic composition is applied to a polymer composition containing polybenzazole short fibers, and the polybenzazole short fibers in the composition are oriented in the thickness direction of the plate-shaped molded body, and then solidified. Manufacturing method of heat conductive molded object. A resin substrate for a conductor circuit , comprising a polymer composition containing polybenzazole short fibers , wherein the polybenzazole short fibers are magnetically oriented in the thickness direction of a plate-like molded product . A magnetic composition is applied to a polymer composition containing polybenzazole short fibers, and the polybenzazole short fibers in the composition are oriented in the thickness direction of the plate-shaped molded body, and then solidified. A method for producing a resin substrate for a conductor circuit . 8. The method of manufacturing a resin substrate for a conductor circuit according to claim 7, wherein a copper foil is further bonded onto the conductor circuit resin substrate, and the copper foil is further etched to form a conductor circuit . 8. The method for producing a resin substrate for a conductor circuit according to claim 7, further comprising forming a conductor circuit on the resin substrate for the conductor circuit by printing .

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