JP2018160637A - High-frequency substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency substrate which is inexpensive and excellent in heat dissipation, which can enhance heat dissipation of the high-frequency substrate mounted with high density and can protect an electronic device from heat generation over a long period of time.SOLUTION: A high-frequency substrate according to the present invention includes a resin film formed with a ceramic film made of aluminum nitride between a glass epoxy board (FR-4) for supplying large power and a substrate for high frequency signal high speed transmission in which a copper layer is formed on at least one surface of a substrate selected from a group consisting of a fluororesin having a low dielectric constant of 5 or less (1GHz), a cycloolefin polymer, and a liquid crystal polymer.SELECTED DRAWING: 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 glass epoxy substrate for high power transmission, a high-frequency signal high-speed transmission substrate in which a copper layer is formed on a substrate having a low dielectric constant, and a resin film on which a ceramic film having high thermal conductivity is formed. And a high-frequency substrate with excellent heat dissipation.

  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 problems, the present inventor has found that a glass epoxy substrate (FR-4) as a substrate for supplying high power, a fluororesin having a low dielectric constant, a cycloolefin polymer, and a liquid crystal polymer. A high-frequency substrate having a resin film in which a ceramic film made of aluminum nitride is formed between a substrate for high-frequency signal high-speed transmission having a copper layer on at least one surface of a kind of base material selected from the group. Thus, the present inventors have found that low cost and excellent heat dissipation can be realized, and have completed the present invention.

 That is, the high-frequency substrate of the present invention includes a glass epoxy substrate for high power supply (FR-4), and a group of fluororesin, cycloolefin polymer, and liquid crystal polymer having a low dielectric constant of 5 or less (1 GHz). A resin film in which a ceramic film made of aluminum nitride is formed is provided between a 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.

  The high-frequency substrate of the present invention is a general-purpose copper-clad glass epoxy substrate (FR-4) and a substrate in which a copper layer is laminated on a base material having a low dielectric constant, which are bonded together by an adhesive layer, and high-power wiring and high-speed transmission. It is possible to wire the wiring for use in one substrate, and an inexpensive high-frequency substrate can be provided. Moreover, since the resin film in which the ceramic film which consists of aluminum nitride which has high heat conductivity is formed between both the board | substrates is excellent in heat dissipation, it can be used conveniently as a reliable high frequency board | substrate.

Hereinafter, embodiments of the present invention will be described in detail.
The high-frequency substrate of the present invention is selected from the group consisting of a glass epoxy substrate for high power supply (FR-4), a fluororesin having a low dielectric constant of 5 or less (1 GHz), a cycloolefin polymer, and a liquid crystal polymer. A resin film in which a ceramic film made of aluminum nitride is formed is provided between a 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.

 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, a high-frequency signal high-speed transmission substrate, and a resin film on which a ceramic film made of aluminum nitride is formed, which are bonded via an adhesive layer. Are combined.

 Hereinafter, (1) a glass epoxy substrate for supplying high power, (2) a substrate for high-frequency signal high-speed transmission, (3) a resin film on which a ceramic film is formed, (4) an adhesive layer, (5) high-frequency It demonstrates in order of the manufacturing method of a board | substrate.

(1) Glass epoxy substrate for supplying large power In the high-frequency substrate of the present invention, a glass epoxy substrate that is inexpensive and widely used as a substrate for supplying large power is used. 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.

(2) High-frequency signal high-speed transmission substrate Since 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, the base material is a material having a low dielectric constant. A kind of substrate selected from the group consisting of a fluororesin, a cycloolefin polymer, and a liquid crystal polymer 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, and a plate shape, but since it is mounted at a high density and used as a wiring substrate for high-speed transmission, the surface of the surface is reduced so as to reduce signal reflection and disturbance. It is desirable to select a film-like substrate having high smoothness.

 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 film 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-speed transmission of high-frequency signals according to the present invention includes a wiring layer on at least one side of the above-described base material. A wiring layer may be provided on both sides.

 As for the copper layer of the wiring layer for high-speed signal transmission of the present invention, it is desirable to form a copper layer formed by sputtering on the underlying layer. 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-frequency signal high-speed transmission, 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) Resin film on which a ceramic film is formed The high-frequency substrate of the present invention is insulated between a glass epoxy substrate (FR-4) for supplying high power and a high-frequency signal high-speed transmission substrate on which a copper layer is formed. A resin film on which a ceramic film made of aluminum nitride as a body is formed is disposed.

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

  The resin film is not particularly limited, but is preferably a polyimide (PI) film or a polyethylene terephthalate (PET) film from the viewpoints of heat resistance by sputtering treatment and ease of handling.

 In order to dissipate heat efficiently, the aluminum nitride film preferably has a thickness 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.

(4) Adhesive layer The resin film on which the aluminum nitride film is formed is provided between the glass epoxy substrate for high power supply (FR-4) and the high-frequency signal high-speed transmission substrate on which the copper layer is formed. They are bonded together 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 suitable for the substrate to be used can be used. Prepregs are commercially available and are preferably used.

(5) 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 preparing a copper-clad glass epoxy substrate (FR-4) as a substrate for supplying high power (B) A resin film formed with a ceramic film made of aluminum nitride is prepared, and the copper paste of (A) A step of attaching a glass epoxy substrate (C) A step of producing a high-frequency signal high-speed transmission substrate and attaching it on the resin film of (B) to form a high-frequency substrate.

Hereinafter, each process will be described.
(A) Step of preparing a copper-clad glass epoxy substrate (FR-4) as a large power supply substrate As described above, the glass epoxy substrate (FR-4) prepared as a large power supply substrate is particularly limited. Instead of a product, 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 can be obtained.

(B) The process of producing the resin film which formed the ceramic film which consists of aluminum nitride, and affixing the copper adhesion glass epoxy substrate of (A) First, the resin film which formed the aluminum nitride film was produced . As a resin film. A polyimide (PI) film or a polyethylene terephthalate (PET) film can be used.

 An aluminum nitride film that exhibits a heat dissipation effect can be formed by a dry process 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. A method of synthesizing and pulverizing aluminum nitride to form fine particles of aluminum nitride is also conceivable. However, sputtering is most preferable in order to exhibit efficient heat dissipation.

 The aluminum nitride film 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 film having a predetermined thickness. Can be obtained. The film thickness is preferably in the range of 1 μm to 10 μm, and more preferably 1 μm to 3 μm. 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.

 The resin film on which the aluminum nitride film obtained as described above is formed is attached to a copper-clad glass epoxy substrate by thermocompression bonding using an adhesive or a prepreg.

C) Step of producing a high-frequency signal high-speed transmission substrate and attaching it to the resin film of (B) to make a high-frequency substrate First, a high-frequency signal high-speed transmission substrate is produced. As the base material of the high-frequency signal high-speed transmission substrate, a kind of base material selected from the group consisting of a fluororesin, a cycloolefin polymer, and a liquid crystal polymer, which is a material having a low dielectric constant (relative permittivity of 5 at 1 GHz) is used. be able to. 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.

Finally, the obtained high-frequency signal high-speed transmission substrate is bonded with an adhesive or prepreg on a resin film on which an aluminum nitride film is bonded to the copper-coated glass epoxy substrate obtained in the step (B). The high frequency substrate of the present invention can be obtained by laminating and thermocompression bonding.
In addition, as a manufacturing method of the high frequency board | substrate of this invention, it is not necessarily necessarily performed in order of the process of (A), (B), (C), The high frequency signal high-speed transmission board | substrate of (C) is produced first. In addition, the bonding with the adhesive or the prepreg can be finally processed collectively.

 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, a polyimide film (Upilex S (registered trademark) manufactured by Ube Industries, Ltd., thickness: 12.5 μm) is prepared as a resin film for forming an aluminum nitride film, cut into a 20 cm square, and then a sputtering apparatus (Shibaura). The aluminum nitride film was formed to 1.2 μm on one side of this polyimide film. 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 30 minutes to obtain an aluminum nitride film having a thickness of 1.2 μm.

Next, as a substrate for high-speed transmission, 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. is prepared and cut into a 20 cm square. Then, it was set in a sputtering apparatus (manufactured by Shibaura Mechatronics Corporation, model: CFS-4ES). First, Ni-25 mass% Cr 20 nm and copper 100 nm were formed on both sides of this polyimide film as a base layer. 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 for wiring was 4 μm on both sides.

  A prepreg (product number: GEA-770G, thickness 25 μm) manufactured by Hitachi Chemical Co., Ltd. was prepared as a material for the adhesive layer. A glass epoxy substrate on which the wiring pattern is formed, a polyimide film on which the aluminum nitride film is formed, and a high-speed transmission substrate in which a copper layer is plated on both surfaces of the film are bonded together by a prepreg, and 270 ° C. Were bonded by thermocompression bonding for 10 minutes to obtain a high-frequency substrate.

  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 35 ° 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, the thermal conductivity of the substrate was 3.5 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 40 ° C. The thermal conductivity of the substrate was 3.2 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 one hour operation was 48 ° C. The thermal conductivity of the substrate was 3.0 W / m · K.

(Comparative Example 1)
A high frequency substrate was obtained in the same manner as in Example 1 except that the resin film on which the aluminum nitride film was formed was not provided. As a result of evaluating the heat dissipation performance of the high-frequency substrate in the same manner as in Example 1, the temperature of the substrate after one hour operation was 70 ° C. The thermal conductivity of the substrate was 0.4 W / m · K.

 As described above, it can be seen that the high-frequency substrate of the present invention is a substrate excellent in heat dissipation, and can be suitably used as a wiring substrate for high-speed transmission of high-frequency signals.

Claims (3)

 At least one surface of a glass epoxy substrate for high power supply (FR-4) and a kind of base material selected from the group of fluororesins, cycloolefin polymers, and liquid crystal polymers having a low dielectric constant of 5 or less (1 GHz) A high-frequency substrate comprising: a resin film having a ceramic film made of aluminum nitride formed between the substrate and a high-frequency signal high-speed transmission substrate on which a copper layer is formed.   The high frequency substrate according to claim 1, wherein the ceramic film has a thickness of 1 μm to 10 μm.   The high-frequency substrate according to claim 1, wherein the copper layer has a thickness of 1 μm to 20 μm.