JP2018160638A - High-frequency substrate - Google Patents

Abstract

An object of the present invention is to provide a high-frequency board that is inexpensive and excellent in heat dissipation, capable of improving heat dissipation of a high-frequency board mounted with high density and protecting electronic equipment from heat generation over a long period of time. A high frequency substrate according to the present invention includes a glass epoxy substrate for high power supply (FR-4) on which an aluminum nitride layer and an aluminum oxide layer are formed, and a relative dielectric constant of 5 or less (1 GHz). An adhesive layer is provided between the substrate for high-frequency signal high-speed transmission in which a copper layer is formed on at least one surface of a kind of base material selected from the group consisting of a fluororesin having a low dielectric constant, a cycloolefin polymer (COP), and a liquid crystal polymer. A high-frequency substrate provided. [Selection figure] None

Description

 The present invention relates to a high-frequency substrate having a high-power transmission function and a high-frequency signal high-speed transmission function. More specifically, a high-power transmission glass epoxy substrate on which a ceramic film made of aluminum nitride and aluminum oxide having high thermal conductivity is formed, and a high-frequency signal in which a copper layer is formed on a substrate having a low dielectric constant The present invention relates to a high-frequency substrate excellent in heat dissipation provided with a high-speed transmission substrate.

  In recent years, along with the demand for higher performance and smaller size of electronic devices, higher density and higher functionality of electronic components such as semiconductors have been demanded. In particular, the amount of heat generated per unit volume is increasing due to the increase in communication speed in addition to the reduction in size of communication devices that use high-frequency bands.

 Various problems have been pointed out for practical use of such high-frequency signal high-speed transmission devices, but one of the biggest problems is a heat generation problem. Since it operates at high output and high density, it becomes hot and its reliability is greatly reduced. Therefore, it is an important issue to prevent the deterioration of reliability and improve long-term reliability by quickly and efficiently dissipating this heat generation.

 In order to realize high-speed transmission of high-frequency signals, various wiring board improvements have been studied. Usually, printed circuit boards used in high-frequency circuits are selected based on a comprehensive judgment of the frequency to be used, allowable size, cost, etc., but glass fiber, epoxy resin, and aramid fiber A substrate in which an electrolytic copper foil is attached to an epoxy resin or a polyimide resin having flexibility has been used.

 For example, Patent Document 1 discloses a high-frequency substrate in which molybdenum, iron, cobalt, nickel, and tungsten are added to increase the adhesion with a copper foil to be attached to a printed base material and the copper particle size is increased. Has been. However, high-frequency transmission has a problem in that a signal is reflected at this coarsened location and signal transmission loss increases.

 In Patent Document 2, for the purpose of reducing transmission loss, a copper foil of a high-frequency substrate is subjected to a roughening process with spherical particles having a diameter of 0.05 μm to 1.0 μm, and molybdenum, nickel, tungsten, or the like is further formed thereon. A method for manufacturing a high-frequency substrate in which a metal heat-resistant layer, a chromate film layer, and a silane coupling agent layer are laminated is disclosed. However, in order to form these laminates, there are problems that a complicated process is required and the surface roughness of the obtained copper foil is not sufficient for a high-frequency substrate. As described above, in order to respond to the strong demand that is widely adopted as a high-frequency substrate, a high-quality and low-cost high-frequency substrate is required.

JP-A-11-256389 JP 2006-210689 A

 An object of the present invention is to provide an inexpensive high-frequency substrate that can improve heat dissipation of a high-density mounted high-frequency substrate and protect an electronic device from heat generation over a long period of time.

 As a result of intensive studies to solve the above-mentioned problems, the present inventor has, as a configuration of a high-frequency substrate, a glass epoxy substrate for high power supply (FR−) in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface. 4) and a high-frequency signal high-speed transmission substrate having a copper layer on at least one surface of a kind of base material selected from the group consisting of a fluororesin having a low dielectric constant, a cycloolefin polymer, and a liquid crystal polymer are bonded together by an adhesive layer. As a result of the construction, the present inventors have found that it is inexpensive and has excellent heat dissipation, and have completed the present invention.

 That is, the high-frequency substrate of the present invention has a high power supply glass epoxy substrate (FR-4) in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface, and a low dielectric constant of 5 or less (1 GHz). And a high-frequency signal high-speed transmission substrate having a copper layer formed on at least one surface of a substrate selected from the group consisting of a fluororesin having a dielectric constant, a cycloolefin polymer, and a liquid crystal polymer.

  The high-frequency substrate of the present invention has a configuration in which a general-purpose copper-clad glass epoxy substrate (FR-4) and a substrate having a low dielectric constant obtained by laminating a copper layer are bonded together by an adhesive layer, and high-power wiring and high-speed wiring Transmission wiring can be wired in one substrate, and an inexpensive high-frequency substrate can be provided. In addition, since it has a heat dissipation layer composed of an aluminum nitride layer and an aluminum oxide layer having high thermal conductivity on the surface of the copper-bonded glass epoxy substrate, it has excellent heat dissipation and is suitably used as a highly reliable high-frequency substrate. be able to.

Hereinafter, embodiments of the present invention will be described in detail.
The high-frequency substrate of the present invention includes a glass epoxy substrate for high power supply (FR-4) in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface, and a low dielectric constant having a relative dielectric constant of 5 or less (1 GHz). A high-frequency signal high-speed transmission board having a copper layer formed on at least one surface of a kind of base material selected from the group consisting of a fluororesin, a cycloolefin polymer, and a liquid crystal polymer.

 The high-frequency board of the present invention enhances the heat dissipation of the board mounted at high density, and prevents the deterioration of the reliability of the mounted electronic equipment by efficiently radiating the heat generated by long-term use. Excellent heat dissipation as a high frequency substrate. The shape of the high-frequency substrate of the present invention is not particularly limited as long as it has excellent heat dissipation properties. For example, the thickness of the resin film or the copper layer for wiring of the base material of the high-speed transmission substrate can be used. It can be adjusted as needed.

 The high-frequency substrate of the present invention comprises a glass epoxy substrate for supplying high power, in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface, and a substrate for high-frequency signal high-speed transmission, which are bonded via an adhesive layer. Are combined.

 Hereinafter, regarding the present invention, (1) a glass epoxy substrate for supplying high power in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface, (2) a substrate for high-frequency signal high-speed transmission, (3) an adhesive layer, (4) The method for manufacturing a high-frequency substrate will be described in this order.

(1) Glass epoxy substrate for large power supply in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface In the high frequency substrate of the present invention, a glass epoxy that is inexpensive and widely used as a substrate for large power supply Use a substrate. In the present invention, as the glass epoxy substrate, a commercially available copper-coated glass epoxy substrate (FR-4, hereinafter sometimes referred to as a glass epoxy substrate) can be used. The glass epoxy substrate FR-4, which can handle large currents and fine wiring, is widely used for electronic equipment. It is an abbreviation of “Frame Regentant Type 4”, and a glass fiber cloth is impregnated with an epoxy resin and heat-cured. It is a base material having high strength, heat resistance and insulation. Copper foil is attached to this base material, and it is frequently used as a printed circuit board. Examples thereof include glass epoxy substrates (product numbers: MCL-E-770G, MCL-E-700G, MCL-E-705G, etc., electrolytic copper foils 5 μm, 12 μm, 18 μm, 35 μm, etc.) manufactured by Hitachi Chemical Co., Ltd.

 In the present invention, an aluminum nitride layer and an aluminum oxide layer are formed on the surface of the glass epoxy substrate in order to impart heat dissipation and insulation.

 In the present invention, aluminum nitride is selected as a ceramic having an insulator and high thermal conductivity. Aluminum nitride has a thermal conductivity of 285 W / mK, which is a material having thermal conductivity close to 398 W / mK, which is the thermal conductivity of copper as a wiring material. By selecting aluminum nitride, high insulation and efficient heat dissipation required for a high-frequency substrate are imparted. Aluminum oxide is also an insulator and is a ceramic having a relatively high thermal conductivity of 30 W / mK.

  High heat dissipation of the high-frequency substrate of the present invention can be ensured by the aluminum nitride layer and the aluminum oxide layer.

 The aluminum nitride layer of the present invention is required to have a dense film quality and high adhesion to the substrate in order to efficiently dissipate heat. Therefore, in order to satisfy this requirement, a film formed by a dry method such as a chemical vapor deposition method, a physical vapor deposition method, or a sputtering method can be realized.

 The thickness of the aluminum nitride layer is preferably in the range of 1 μm to 10 μm, and more preferably 1 μm to 3 μm. If the thickness is less than 1 μm, the heat dissipation effect is insufficient, and even if the thickness exceeds 10 μm, the improvement of the heat dissipation effect is not seen and the cost increases.

 In the present invention, an aluminum oxide layer is formed between the glass epoxy substrate and the aluminum nitride layer. The aluminum oxide layer is made of an aluminum oxide powder having a particle size of 1 μm or more and 5 μm or less. As a method of forming an aluminum oxide layer with aluminum oxide powder, for example, by blasting aluminum oxide powder onto the surface of a glass epoxy substrate, fine aluminum oxide particles are implanted into the substrate surface to form an aluminum oxide layer. can do. In this way, an aluminum oxide layer as a base layer is formed, and by forming an aluminum nitride layer by a direct sputtering method on the aluminum oxide layer whose adhesion with the substrate is improved by an anchor effect, an extremely high heat dissipation effect, High adhesion can be imparted.

  As the aluminum oxide powder, a powder having a particle size of 1 μm to 5 μm can be preferably used. When aluminum oxide powder having a particle size in the range of 1 μm to 5 μm is selected, the aluminum oxide powder is appropriately driven into the substrate and remains on the substrate by an anchor effect to form an aluminum oxide layer. If the particle size of the aluminum oxide powder is less than 1 μm, it is difficult to remain on the substrate and the coverage is lowered, which is not preferable. If it exceeds 5 μm, it becomes difficult to form a smooth film of an aluminum nitride layer that is subsequently laminated and formed.

 By using this aluminum oxide powder, an aluminum oxide layer can be formed by spraying the glass epoxy substrate with compressed air of 0.6 MPa to 1.0 MPa. The aluminum oxide layer is formed on the surface of the glass epoxy substrate, and the coverage is 20% or more, preferably 50% or more. A higher coverage is preferable, but it is not necessary to cover 100% of the entire surface of the substrate, and an anchor effect can be exhibited as long as at least a 20% range is covered. An aluminum oxide layer is formed as a base layer for forming an aluminum nitride layer for achieving excellent heat dissipation in the present invention. As described above, a glass epoxy substrate for supplying high power in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface is manufactured.

(2) High-frequency signal high-speed transmission substrate The high-frequency signal high-speed transmission substrate of the present invention is required to have a low dielectric constant and dielectric loss tangent and low signal loss. A kind of substrate selected from the group consisting of fluororesin, cycloolefin polymer, and liquid crystal polymer as materials is used.

 The dielectric constant greatly affects the speeding up of the signal. The lower the dielectric constant, the higher the signal speed. Further, it is also required that the signal loss is small as a high-speed transmission substrate. The smaller the dielectric loss tangent, the less signal loss. Thus, high-speed transmission substrates are required to have a low dielectric constant and dielectric loss tangent. In the present invention, it is necessary to use a substrate having a relative dielectric constant of 5 or less (1 GHz) as the range of the dielectric constant. Moreover, it is preferable to use the base material whose dielectric loss tangent is 0.02 or less (1 GHz). In the present invention, a fluororesin, a cycloolefin polymer, and a liquid crystal polymer can be suitably used as the substrate.

 Specifically, for example, cycloolefin polymer ZEONOR (registered trademark, product number: ZF14, thickness 100 μm, relative dielectric constant 4.73, dielectric loss tangent 0.02) manufactured by Nippon Zeon Co., Ltd., fluorine resin manufactured by Nippon Valqua Industries, Ltd. (Product number: TLY-5A, thickness 380 μm, relative dielectric constant 2.17, dielectric loss tangent 0.0009), liquid crystal polymer manufactured by Sumitomo Chemical Co., Ltd. (product number: LCPE4008, thickness 100 μm, relative dielectric constant 4.5, dielectric loss tangent) 0.018).

 The form of the base material is not particularly limited, such as a film shape, a sheet shape, a plate shape, etc., but since it is mounted at a high density and used as a wiring board for high-speed transmission, a film-like base material with high surface smoothness is selected It is desirable to do.

 Although the thickness can be selected depending on the use and purpose of use of the high-frequency substrate of the present invention, the thickness of the resin film used as the base material is preferably in the range of 10 μm to 400 μm, preferably 20 μm to 200 μm. A range is more preferred.

 If the thickness of the resin film is less than 10 μm, it is not preferable because the strength as a substrate for supporting the wiring copper layer is insufficient. When the thickness of the resin film exceeds 400 μm, it is not preferable because the heat generated on the wiring side is not easily transmitted to the aluminum nitride layer having a heat dissipation function. Moreover, since workability and handling property deteriorate, it is not preferable.

 The wiring layer for high-frequency signal high-speed transmission of the high-frequency substrate of the present invention uses copper that has a low electrical resistance and is generally used in electrical wiring circuits. Copper is preferable because it is relatively inexpensive in terms of cost and easy to process wiring.

 The thickness of the copper layer for wiring can be arbitrarily set, but the thickness of the copper layer for wiring when used as a high-frequency substrate mounted with high density can be in the range of 1 μm to 20 μm. In order to further increase the density, a copper layer having a thickness of 1 μm or more and 4 μm or less is preferable. If the thickness is less than 1 μm, the wiring layer is too thin, which may cause disconnection. If the thickness exceeds 20 μm, the cross section of the wiring becomes trapezoidal, resulting in a difference in the wiring width between the upper and lower wirings. When wiring at a high density, there is a risk of short circuit failure between the wirings, which is not preferable.

 The copper layer of the wiring layer for high-frequency signal high-speed transmission according to the present invention includes a wiring layer on at least one side of the base material. A wiring layer may be provided on both sides.

 As for the copper layer of the high-frequency signal high-speed transmission wiring layer of the present invention, it is desirable to form a copper layer formed by sputtering on the underlayer. The adhesion between the copper layer formed by sputtering and the substrate is extremely high due to chemical bonding. By selecting a base material having a smooth surface, the copper layer obtained by the sputtering method is also a smooth film because the film is formed directly on the surface of the smooth base material without roughening the surface. Further, a smooth film can be obtained from the copper layer formed by plating. Therefore, when high-frequency signals are transmitted at high speed using the high-frequency substrate of the present invention, signal reflection and disturbance are less likely to occur, and signal transmission loss can be reduced.

 Since the copper layer for wiring of the high-frequency substrate of the present invention is used as wiring for high-speed transmission of high-frequency signals, it is required to have a film quality with good etching properties when wiring processing is performed later. The wiring copper layer for satisfying these required characteristics can be realized by forming a film by a dry method such as chemical vapor deposition, physical vapor deposition, or sputtering. In particular, the sputtering method is suitable for obtaining a dense film and a smooth film or a film having higher adhesion. However, the film formation time becomes long, which is disadvantageous in terms of cost.

 Therefore, in order to make use of the characteristics of the sputtering method and compensate for the decrease in productivity, the wiring copper layer of the high-frequency substrate of the present invention is first formed by forming a copper layer as a base layer on the surface of the base material by the sputtering method, It is obtained by forming a copper layer with a predetermined thickness by electroplating.

 That is, the copper layer of the high-frequency signal high-speed transmission wiring layer of the present invention is formed by forming a copper layer as a base layer with a thickness of 50 nm or more and 300 nm or less by a sputtering method, and then finally forming a copper layer for wiring by an electroplating method. In particular, the copper layer for wiring can be formed by forming the film so as to have a thickness of 1 μm to 20 μm.

 The copper layer of the underlayer is obtained by setting a base material in a sputtering device using a copper target and sputtering while introducing argon gas to form a copper layer having a predetermined thickness. . In order to further improve the adhesion between the base material and the copper layer, the base layer selected from the group consisting of chromium, nickel, and nickel-chromium alloy is formed to a thickness of 20 nm to 100 nm before forming the copper layer. It is preferable to form a film. In addition, it is effective to improve the adhesion by cleaning the surface of the base material with argon ions or applying oxygen plasma to activate the base material surface.

 Next, the base material on which the copper layer of the base layer is formed is subjected to copper plating with a plating apparatus, and a copper layer for wiring is formed so that the final thickness is 1 μm or more and 20 μm or less. For copper plating, it is desirable to use an oxidation bath plating apparatus using copper sulfate which is less toxic and excellent in operability.

(3) Adhesive layer In the high frequency substrate of the present invention, a copper layer is formed on at least one surface of a glass epoxy substrate for supplying high power, in which an aluminum nitride layer and an aluminum oxide layer are formed on the substrate surface, and a substrate having a low dielectric constant. The formed high-frequency signal high-speed transmission substrate is bonded via an adhesive layer.

  The adhesive layer is not particularly limited as long as it can adhere to the base material used for the substrate, and an adhesive or a prepreg can be used, but a thermosetting resin prepreg suitable for the substrate to be used. Is commercially available and is preferably used.

(4) Manufacturing method of high frequency board | substrate The manufacturing method of the high frequency board | substrate of this invention is demonstrated below. The high-frequency substrate of the present invention is obtained by the following steps (A) to (C).
(A) A step of forming an aluminum nitride layer and an aluminum oxide layer on the surface of a copper-coated glass epoxy substrate (FR-4) for supplying high power (B) A step of producing a high-frequency signal high-speed transmission substrate (C) (A) A step of attaching a glass epoxy substrate for supplying high power with an aluminum nitride layer and an aluminum oxide layer formed on the surface and (B) a substrate for high-frequency signal high-speed transmission to form a high-frequency substrate.

Hereinafter, each process will be described.
(A) Step of forming an aluminum nitride layer and an aluminum oxide layer on the surface of a copper-epoxy glass epoxy substrate (FR-4) for supplying high power As described above, a glass epoxy substrate prepared as a substrate for supplying high power (FR-4) is not particularly limited, and a commercially available glass epoxy substrate is obtained according to the purpose of use. A wiring layer with a copper layer attached and a wiring pattern set is commercially available, and is obtained.

 Next, an aluminum oxide layer is formed by spraying aluminum oxide powder having a particle size of 1 μm to 5 μm on a glass-epoxy substrate with compressed air of 0.6 MPa to 1.0 Mpa and blasting. The aluminum oxide layer is formed on the surface of the glass epoxy substrate, but it is preferable that the coverage is high. However, it is not necessary to cover the entire surface of the substrate 100%, and it is sufficient that at least 20% is covered.

 Subsequently, an aluminum nitride layer is formed. In order to ensure high heat dissipation of the high-frequency substrate of the present invention, high adhesion to the substrate is required for the aluminum nitride layer functioning as a heat dissipation film. An aluminum nitride layer for satisfying these required characteristics can be realized by forming a film by a dry method such as chemical vapor deposition, physical vapor deposition, or sputtering. A method of synthesizing and pulverizing aluminum nitride to form an aluminum nitride layer is also conceivable. However, it is difficult to obtain a dense film because adhesion with the substrate cannot be expected. Therefore, the sputtering method is suitable for obtaining a dense aluminum nitride layer with higher adhesion.

 The conditions for forming the aluminum nitride layer by sputtering are as follows. The aluminum nitride layer is formed by setting a base material in a sputtering apparatus using a metal aluminum target, and performing sputtering while introducing nitrogen gas to form an aluminum nitride layer having a predetermined thickness. Can be obtained. The film thickness is preferably 1 μm or more and 10 μm or less, more preferably 1 μm or more and 3 μm or less. If the film thickness is less than 1 μm, the heat dissipation effect is insufficient, and even if the film thickness exceeds 10 μm, the heat dissipation effect is not improved, and the cost increases.

(B) Step of manufacturing a high-frequency signal high-speed transmission substrate First, a high-frequency signal high-speed transmission substrate is manufactured. The base material of the substrate for high-speed transmission of high-frequency signals is a kind of base material selected from the group consisting of fluororesin, cycloolefin polymer, and liquid crystal polymer, which is a material having a low dielectric constant (relative dielectric constant at 1 GHz of 5 or less). Can be used. For example, cycloolefin polymer ZEONOR (registered trademark, product number: ZF14, thickness, 100 μm, dielectric constant 4.73, dielectric loss tangent 0.02) manufactured by Nippon Zeon Co., Ltd., fluorine resin (product number: TLY- 5A, thickness 380 μm, dielectric constant 2.17, dielectric loss tangent 0.0009), liquid crystal polymer (product number: LCPE4008, thickness 100 μm, dielectric constant 4.5, dielectric loss tangent 0.018) manufactured by Sumitomo Chemical Co., Ltd. be able to.

 A base material having a low dielectric constant as described above is prepared. First, a copper layer having a thickness of 50 nm or more and 300 nm or less is formed on the base layer by sputtering, and an electroplating method is formed thereon. Thus, a copper layer having a thickness of 1 μm or more and 20 μm or less in total is formed.

  The thickness of the high-speed transmission wiring can be arbitrarily set according to the desired wiring width, and is not particularly limited, but the thickness of the copper foil of a normal wiring board is about 36 μm, In comparison, since the thickness of the thin copper layer can be 1 μm or more and 20 μm or less, there is an advantage that the etching time can be shortened and fine wiring can be easily formed.

  In addition, since a copper layer is formed by sputtering on the underlayer, the adhesion to the base material is good, a smooth and dense film quality is obtained, and the copper layer for wiring with low resistance and low signal attenuation is obtained. can do.

(C) (A) A step of attaching a high-power glass epoxy substrate having an aluminum nitride layer and an aluminum oxide layer formed on the substrate surface and (B) a high-frequency signal high-speed transmission substrate to form a high-frequency substrate. Finally, (A) a glass epoxy substrate for supplying high power with an aluminum nitride layer and an aluminum oxide layer formed on the substrate surface, and (B) a substrate for high-frequency signal high-speed transmission are bonded using an adhesive or prepreg. By combining and thermocompression bonding, the high-frequency substrate of the present invention can be obtained.

 The adhesive layer is not particularly limited as long as it can adhere to the base material used for the substrate, and an adhesive or a prepreg can be used, but a thermosetting resin suitable for the substrate to be used can be used. Prepregs are commercially available and are preferably used.

 Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
First, a glass epoxy substrate (product number: MCL-E-770G, substrate thickness 110 μm, electrolytic copper foil 12 μm) manufactured by Hitachi Chemical Co., Ltd. was prepared as a glass epoxy substrate for supplying high power. A glass epoxy substrate having a power supply wiring pattern formed thereon was used.

 Next, an aluminum oxide layer is formed on the surface of the glass epoxy substrate by spraying aluminum oxide powder (particle size 3 μm product) manufactured by Sumitomo Chemical Co., Ltd. onto the glass epoxy substrate on the glass epoxy substrate with compressed air of 1.0 Mpa. When the surface was visually observed using an optical microscope, the coverage was about 30%.

Thereafter, the glass epoxy substrate on which the aluminum oxide layer was formed was set in a sputtering apparatus (CFS-4ES, manufactured by Shibaura Mechatronics Co., Ltd.). An aluminum nitride film was formed on the substrate surface. As film formation conditions, a metal aluminum target (purity 99.99%) was used as a target, the ultimate vacuum was 6.5 × 10 ⁻³ Pa, the DC output was 350 W, and the reaction gas was Argon gas (flow rate 15 sccm) and nitrogen gas (flow rate 15 sccm) were introduced, and the film was formed for 40 minutes to obtain an aluminum nitride film having a thickness of 1.4 μm.

 Next, as a substrate for high-speed transmission, prepare a cycloolefin polymer ZEONOR (registered trademark, product number ZF14, substrate thickness 100 μm, relative dielectric constant 4.73, dielectric loss tangent 0.02) manufactured by Nippon Zeon Co., Ltd. in a 20 cm square. Cut and set in a sputtering apparatus (CFS-4ES, manufactured by Shibaura Mechatronics Co., Ltd.).

First, 20 nm of Ni-25 mass% Cr and 200 nm of copper were formed on both sides of this polyimide film as an underlayer. Specifically, using a disk target having a diameter of 3 inches of Ni-25 mass% Cr alloy (purity 99.9%) and copper (purity 99.9%) as the target, the ultimate vacuum is 6. 5 × 10 ⁻³ Pa, DC output is 200 W, and argon gas (flow rate: 15 sccm) is introduced as a reaction gas. A% Cr underlayer was formed. Subsequently, the DC output was set to 300 W, the ultimate vacuum was set to 6.5 × 10 ⁻³ Pa, and argon gas (flow rate: 15 sccm) was introduced as a reaction gas, so that the bottom of the copper film having a thickness of 200 nm was formed at room temperature. A formation was formed.

In order to perform electrolytic copper plating on the obtained film, a film having a base layer formed thereon was set on a double-side plating apparatus using copper sulfate. The plating conditions were a bath temperature of 45 ° C., a voltage of 5 V, a current density of 3 A / dm ² , plating for 15 minutes, and a high-speed transmission substrate having copper layers plated on both sides of the film was produced. The thickness of the obtained copper layer was 4 μm on both sides of the wiring copper layer.

  A prepreg (product number: GEA-770G, thickness 25 μm) manufactured by Hitachi Chemical Co., Ltd. was prepared as a material for the adhesive layer. The glass epoxy substrate on which the aluminum nitride layer and the aluminum oxide layer are formed and the high-speed transmission substrate having the copper layer are bonded with a prepreg and bonded by thermocompression bonding at 270 ° C. for 10 minutes. A substrate was obtained.

  The heat dissipation performance of the obtained high frequency substrate was evaluated. An LED light of 10 W in total was attached to the obtained substrate and operated for 1 hour while blinking 100 times per second, and a thermo tape was attached to the back surface of the substrate, and the substrate temperature after the operation was measured. As a result, the temperature of the substrate after one hour operation was 30 ° C. Moreover, the thermal conductivity of the obtained board | substrate was measured using the thermal conductivity measuring apparatus (Advance Riko Co., Ltd. make, laser flash method, model number: TC-9000). As a result, it was 4.2 W / m · K.

(Example 2)
Using a fluororesin base material (product number: TLY-5A, thickness: 380 μm) manufactured by Nippon Valqua Industries, Ltd. as the base material for the high-speed transmission substrate, a bonding film manufactured by Nippon Valqua Industries, Ltd. (product number: HT1.5) A high frequency substrate was obtained in the same manner as in Example 1 except that.

 The heat dissipation performance of the obtained high frequency substrate was evaluated in the same manner as in Example 1. The temperature of the substrate after one hour operation was 48 ° C. The thermal conductivity of the substrate was 3.0 W / m · K.

(Example 3)
Using a liquid crystal polymer substrate (product number: LCPE4008, thickness 100 μm) manufactured by Sumitomo Chemical Co., Ltd. as the substrate for the high-speed transmission substrate, and using a bonding film (product number: HT1.5) manufactured by Nippon Valqua Industries, Ltd. as the adhesive layer A high frequency substrate was obtained in the same manner as in Example 1 except that.

 The heat dissipation performance of the obtained high frequency substrate was evaluated in the same manner as in Example 1. The temperature of the substrate after operating for one hour was 51 ° C. The thermal conductivity of the substrate was 2.8 W / m · K.

(Comparative Example 1)
A high frequency substrate was obtained in the same manner as in Example 1 except that a glass epoxy substrate was used without forming an aluminum nitride layer and an aluminum oxide layer. As a result of evaluating the heat dissipation performance of the high-frequency substrate in the same manner as in Example 1, the substrate temperature was 70 ° C. The thermal conductivity of the substrate was 0.4 W / m · K.

 As described above, the high-frequency substrate of the present invention has good heat dissipation performance and is excellent in heat dissipation, and is an optimal substrate as a high-frequency transmission wiring substrate.

Claims (4)

 A glass epoxy substrate (FR-4) for supplying high power with an aluminum nitride layer and an aluminum oxide layer formed on the surface, a fluororesin and a cycloolefin polymer having a low dielectric constant having a relative dielectric constant of 5 or less (1 GHz) (COP), a high-frequency signal high-speed transmission substrate having a copper layer formed on at least one surface of a kind of base material selected from the group of liquid crystal polymers.   The high-frequency substrate according to claim 1, wherein the aluminum nitride layer has a thickness of 1 μm to 10 μm.   The high-frequency substrate according to claim 1, wherein the aluminum oxide layer is made of an aluminum oxide powder having a particle size of 1 μm or more and 5 μm or less. 4. The high-frequency substrate according to claim 1, wherein the high-speed transmission copper layer has a thickness of 1 μm to 20 μm.