JP2018160636A - 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 of the present invention is a glass epoxy substrate for supplying high power on one side of an adhesive layer made of an epoxy resin containing at least one ceramic particle selected from the group of aluminum nitride, aluminum oxide, and silicon carbide. A kind of base material selected from the group consisting of a fluororesin, cycloolefin polymer (COP), and liquid crystal polymer having a low dielectric constant of 5 or less (1 GHz) on the other surface. The high-frequency substrate includes a high-frequency signal high-speed transmission substrate having a copper layer disposed on at least one side. [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 glass epoxy substrate for high power transmission, a substrate for high-speed transmission of a high frequency signal in which a copper layer is formed on a base material having a low dielectric constant, and an epoxy resin adhesive layer including ceramic powder having high thermal conductivity 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) is used as a high power supply substrate and a fluororesin having a low dielectric constant as a high frequency signal high speed transmission substrate, Epoxy containing at least one ceramic particle selected from the group consisting of aluminum nitride, aluminum oxide, and silicon carbide, and a substrate having a copper layer on at least one surface of one type of substrate selected from the group of olefin polymers and liquid crystal polymers It has been found that by using a high-frequency substrate configured to be bonded by an adhesive layer made of a resin, low cost and excellent heat dissipation can be realized, and the present invention has been completed.

 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). Contains at least one ceramic particle selected from the group consisting of aluminum nitride, aluminum oxide, and silicon carbide between a substrate for high-frequency signal high-speed transmission in which a copper layer is formed on at least one surface of a selected substrate. An adhesive layer made of an epoxy resin is provided.

  The high-frequency substrate of the present invention is for high power use by bonding 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 through an adhesive layer. Wiring and high-speed transmission wiring can be wired in one substrate, and an inexpensive high-frequency substrate can be provided. In addition, since the adhesive layer contains ceramic particles having high thermal conductivity, it can be suitably used as a high-reliability high-frequency substrate with excellent heat dissipation.

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. Epoxy resin containing at least one ceramic particle selected from the group consisting of aluminum nitride, aluminum oxide, and silicon carbide between a substrate for high-frequency signal high-speed transmission in which a copper layer is disposed on at least one surface of a substrate. It is characterized by providing the contact bonding layer which consists of.

 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. For example, the resin film of the base material of the high-speed transmission substrate and the thickness of the copper layer for wiring are intended for use. Etc. can be selected and adjusted as necessary.

 The high-frequency substrate of the present invention includes a glass epoxy substrate for supplying high power, a high-frequency signal high-speed transmission substrate, and an adhesive layer.

 Hereinafter, the present invention will be described in the order of (1) a glass epoxy substrate for supplying high power, (2) a substrate for high-frequency signal high-speed transmission, (3) an adhesive layer, and (4) a method for producing a high-frequency substrate.

(1) Glass epoxy substrate for supplying large electric power The high frequency substrate of the present invention uses a glass epoxy substrate that is inexpensive and widely used as a substrate for supplying large electric power. 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. If the thickness of the resin film exceeds 400 μm, it is not preferable because the heat generated on the wiring side is not easily transferred to the adhesive layer made of an epoxy resin containing ceramic particles 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 high-frequency substrate wiring 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 substrate 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 sputtering, and then finally forming a copper layer for wiring by electroplating. A 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 The high-frequency substrate of the present invention comprises a glass epoxy substrate (FR-4) for supplying high power on one side of the adhesive layer, and a high-frequency signal high-speed transmission comprising a copper layer on at least one side of the other side. A substrate is provided. In other words, the glass epoxy substrate for supplying high power and the substrate for high-frequency signal high-speed transmission are bonded via an adhesive layer, and the high-power wiring and the high-speed transmission wiring are wired in one substrate, so that it is inexpensive. Can provide a high-frequency substrate. In addition, since the adhesive layer contains ceramic particles having high thermal conductivity, the heat dissipation is excellent, so that it can be suitably used as a high-frequency substrate having excellent reliability.

 It is important that the adhesive layer having the above function is an adhesive layer made of an epoxy resin containing at least one kind of ceramic particles selected from the group of aluminum nitride, aluminum oxide, and silicon carbide. By selecting the above materials, efficient heat dissipation and high insulation required for a high-frequency substrate are imparted.

 The high heat dissipation property of the present invention is ensured particularly by the adhesive layer, which can be said to exhibit the heat dissipation effect of the present invention due to the high thermal conductivity of the ceramic particles contained in the epoxy resin. In order to ensure sufficient heat dissipation, it is important to select a material with high thermal conductivity. Aluminum nitride has a thermal conductivity of 285 W / mK, which is close to the thermal conductivity of copper having a high thermal conductivity of 398 W / mK, and aluminum nitride is particularly preferable. In addition, examples of the material having high thermal conductivity include aluminum oxide and silicon carbide.

 Ceramic particles to be included in the epoxy resin are not particularly limited in shape, and spherical, rod-like, plate-like, and scale-like particles can be used, but the shape is spherical in order to exhibit efficient heat dissipation. The particle size is preferably in the range of 1 μm to 10 μm, more preferably 3 μm to 7 μm. When the particle size is less than 1 μm, it is difficult to disperse in the resin, and when the particle size exceeds 10 μm, contact between the particles is reduced, and it is difficult to obtain efficient heat dissipation.

  The content of the epoxy resin and the ceramic particles, which are the materials of the adhesive layer, is 20 parts by mass or more and 80 parts by mass or less when the total amount of the epoxy resin and the ceramic particles is 100 parts by mass. Preferably, it is more preferably 30 parts by mass or more and 60 parts by mass or less. If the amount is less than 20 parts by mass, efficient heat dissipation cannot be obtained. If the amount exceeds 80 parts by mass, the resin becomes too small to be printed, and subsequent handling becomes difficult.

 The obtained epoxy resin containing a ceramic resin is printed on a glass epoxy substrate by screen printing, and further, a high-frequency signal transmission substrate is bonded, heated and thermocompression bonded to obtain the high-frequency substrate of the present invention. be able to.

(4) Manufacturing Method of High Frequency Substrate The manufacturing method of the high frequency substrate of the present invention will be described below. The high-frequency substrate of the present invention is obtained by the following steps (A) to (C).
(A) Step of preparing a copper-clad glass epoxy substrate (FR-4) as a substrate for supplying high power (B) Step of producing a high-frequency signal high-speed transmission substrate (C) Step of (A) Copper-clad glass epoxy substrate A step of forming a high-frequency substrate by bonding the high-frequency signal high-speed transmission substrate obtained by the steps (FR-4) and (B) through an adhesive layer.

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. Get a general-purpose copper-attached glass epoxy substrate 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) Step of manufacturing a high-frequency signal high-speed transmission substrate A base material of the high-frequency signal high-speed transmission substrate includes a fluororesin or a cycloolefin polymer (material having a low dielectric constant (relative dielectric constant at 1 GHz of 5 or less)) ( COP), a kind of substrate selected from the group of liquid crystal polymers 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, and a copper layer having a thickness of 50 nm or more and 300 nm or less is formed on this base material by a sputtering method, and an electroplating method is formed thereon. 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 step of bonding through an adhesive layer to form a high-frequency substrate A copper-coated glass epoxy substrate (FR-4) in the step (A) and a substrate for high-speed transmission of a high-frequency signal obtained in the step (B) Are bonded together via an adhesive layer and thermocompression bonded to obtain a high frequency substrate.

 First, an epoxy resin containing ceramic particles is prepared as an adhesive layer. As described above, the amount of the epoxy resin and the ceramic particles in the adhesive layer is 20 parts by mass or more and 80 parts by mass or less when the total amount of the epoxy resin and the ceramic particles is 100 parts by mass. It is more preferable that the amount be 30 parts by mass or more and 60 parts by mass or less. If the amount is less than 20 parts by mass, efficient heat dissipation cannot be obtained. If the amount exceeds 80 parts by mass, the resin becomes too small to be printed, and subsequent handling becomes difficult.

 Finally, the epoxy resin containing the obtained ceramic resin is printed on a glass epoxy substrate by screen printing, and a high-frequency signal high-speed transmission substrate is bonded and thermocompression bonded to obtain the high-frequency substrate of the present invention. be able to.

 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 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. was prepared as a high-speed transmission substrate.

 Next, the base cycloolefin polymer film is cut into a 20 cm square and set in a sputtering apparatus (CFS-4ES, manufactured by Shibaura Mechatronics Co., Ltd.). A film of 20 nm and 100 nm of copper was formed.

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 is set to 300 W, the ultimate vacuum is set to 6.5 × 10 ⁻³ Pa, and argon gas (flow rate: 15 sccm) is introduced as a reaction gas to form a copper underlayer having a thickness of 100 nm. Filmed and laminated.

 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.

  As a material for the adhesive layer, liquid type epoxy resin 828XA (viscosity 150 to 230 P / 25 ° C.) manufactured by Mitsubishi Chemical Corporation was prepared. Spherical aluminum nitride particles (product having a particle size of 4 μm) were mixed at a blending ratio of 60 parts by mass with respect to 40 parts by mass of the epoxy resin. This was screen-printed to form a 20 μm film on a glass epoxy substrate, and the high-speed transmission substrate provided with the copper layer was bonded thereon and bonded by thermocompression bonding at 270 ° C. 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 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, the thermal conductivity of the substrate was 4.2 W / m · K.

(Example 2)
As the material of the adhesive layer, the ceramic particles to be blended are changed to spherical alumina (product having a particle size of 5 μm) and are mixed in a blending ratio of 60 parts by weight of spherical alumina with respect to 40 parts by weight of the epoxy resin. Thus, a high frequency 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 33 ° C. Moreover, the thermal conductivity of the obtained board | substrate was measured using the thermal conductivity measuring apparatus. As a result, the thermal conductivity of the substrate was 3.8 W / m · K.

(Example 3)
As the material for the adhesive layer, the ceramic particles to be blended are changed to spherical alumina (product having a particle size of 5 μm), and the mixture is mixed at a blending ratio of 30 parts by weight of spherical alumina to 70 parts by weight of the epoxy resin. Thus, a high frequency substrate was obtained. 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 was 37 ° C. Moreover, the thermal conductivity of the obtained board | substrate was measured using the thermal conductivity measuring apparatus. As a result, 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 only 100 parts by mass of the epoxy resin was used as the material for the adhesive layer without mixing ceramic particles. 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. Moreover, the thermal conductivity of the obtained board | substrate was measured using the thermal conductivity measuring apparatus. As a result, the thermal conductivity of the substrate was 0.4 W / m · K.

As described above, the high-frequency substrate of the present invention is found to be a substrate excellent in heat dissipation, and can be suitably used as a high-frequency transmission wiring substrate.

Claims (4)

 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) An adhesive layer made of an epoxy resin containing at least one ceramic particle selected from the group consisting of aluminum nitride, aluminum oxide, and silicon carbide is provided between the high-frequency signal high-speed transmission substrate on which the copper layer is formed. High frequency substrate characterized by   2. The high-frequency substrate according to claim 1, wherein the adhesive layer has a ceramic particle content of 20 parts by mass or more and 80 parts by mass or less when the total amount of the epoxy resin and the ceramic particles is 100 parts by mass.   The high frequency substrate according to claim 1, wherein the ceramic particles are spherical and have a particle size of 1 μm to 10 μm.   The high frequency substrate according to claim 1, wherein the copper layer has a thickness of 1 μm or more and 20 μm or less.