JP6420569B2 - High frequency printed circuit board - Google Patents

Description

  The present invention relates to a printed wiring board for high frequency and a wiring material.

  In recent years, the amount of information communication has been increasing, and in order to respond to this, communication in a high frequency region such as microwaves and millimeter waves has been actively performed in devices such as IC cards and mobile phone terminals. For this reason, a printed wiring board for high frequency with a small transmission loss when used in a high frequency region is required.

  In a general printed wiring board, the transmission speed V and the transmission loss αd are related to the relative permittivity εr, the frequency f, and the dielectric loss tangent tan δ of the dielectric layer as follows (formula (1) and formula (2)). Meet.

  That is, in order to increase the transmission speed V and reduce the transmission loss αd, it is desirable to reduce the relative dielectric constant εr of the dielectric layer. For this reason, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetra are used as dielectric layer materials. It has been proposed to use a fluororesin such as a fluoroethylene copolymer (ETFE) or poly (vinylidene fluoride) (PVdF) (see, for example, Japanese Patent Application Laid-Open Nos. 2001-7466 and 4296250).

JP 2001-7466 A Japanese Patent No. 4296250

However, the thermal expansion coefficient (9 × 10 ⁻⁵ / K) of the fluororesin constituting the dielectric layer is equal to the thermal expansion coefficient (1.7 × 10 ⁻⁵ / K) of the metal (eg, copper) constituting the conductor layer. Therefore, when the dielectric layer and the conductor layer are laminated directly as they are, warpage occurs in the reflow process performed at about 260 ° C., and if this warpage remains, the printed wiring board for high frequency is used. There is a possibility that it cannot be used.

  In addition, since the surface energy of fluororesin is extremely low, the adhesive strength with the conductor layer is insufficient, and when used as a printed wiring board for high frequency, the conductor layer and the dielectric layer peel off during use. There is a risk that. In order to eliminate such a peeling problem, a primer or an adhesive may be disposed between the conductor layer and the dielectric layer to increase the adhesive force. However, the primer or adhesive is applied to the dielectric layer. In general, since the relative permittivity and the dielectric loss tangent are large, there is a possibility that the transmission speed is lowered and the transmission loss is increased.

  Furthermore, in order to solve the above problem of peeling, it is conceivable that the surface of the conductor layer is roughened in advance by etching or the like, but there is a possibility that the transmission speed is lowered and the transmission loss is increased. In other words, in the high-frequency region, current flows through the surface of the conductor due to the skin effect, so roughening the surface of the conductor layer may increase the propagation distance, cause transmission delay, and increase transmission loss due to resistance attenuation. There is.

  The present invention has been made based on the above circumstances, and the present invention provides a high-frequency printed wiring board that sufficiently suppresses the occurrence of warping when heated and has reduced transmission delay and transmission loss. The purpose is to do. The present invention can also be applied to wiring materials such as a high frequency flat cable having a dielectric and a conductor, a high frequency electric wire, and an antenna having the same configuration.

The invention made to solve the above problems is
A printed wiring board for high frequency in which a conductor layer is laminated on at least one surface of a dielectric layer,
The dielectric layer includes at least an intermediate layer and a pair of fluororesin layers laminated on both sides of the intermediate layer,
The ratio of the average thickness of the intermediate layer to the total average thickness of the pair of fluororesin layers is 0.001 or more and 30 or less,
The relative dielectric constant of the intermediate layer is 1.2 or more and 10 or less,
The linear expansion coefficient of the intermediate layer is −1 × 10 ⁻⁴ / ° C. or more and 5 × 10 ⁻⁵ / ° C. or less,
The printed wiring board for high frequency, wherein the adhesive force between the fluororesin layer and the conductor layer is 300 g / cm or more.

  In the printed wiring board for high frequency, the dielectric layer has a pair of fluororesin layers and an intermediate layer having a specific dielectric constant within a certain range, and the ratio of the average thickness of the intermediate layer to the total average thickness of the pair of fluororesin layers is Since it is within the above range, desired electrical performance as the entire dielectric layer can be exhibited, and therefore transmission speed can be improved and transmission loss can be suppressed. And since the thermal expansion coefficient of the said intermediate | middle layer is in the said range, when the said high frequency printed wiring board is heated, the thermal expansion as the whole dielectric material layer can be suppressed by this intermediate | middle layer, Therefore, by heating The occurrence of warpage can be suppressed. Further, the high-frequency printed wiring board has an adhesive force between the fluororesin layer and the conductor layer within the above range, and the adhesion between the two is improved. For example, during circuit formation, the dielectric layer and the conductor layer Is less likely to occur, and it is difficult to cause a decrease in transmission speed and an increase in transmission resistance due to the separation between the dielectric layer and the conductor layer.

The ten-point average roughness (Rz) of the conductor layer is preferably 4.0 μm or less. 2 μm
Is particularly preferred. Thereby, even if a current flows through the surface portion of the conductor due to the skin effect, the propagation distance is unlikely to be long, and a suitable transmission speed and transmission loss can be obtained.

  The fluororesin and the conductor layer are preferably chemically bonded. Thereby, a fluororesin layer and a conductor layer can be easily and reliably bonded with a desired adhesive force.

  The adhesive force between the fluororesin layer and the conductor layer is preferably 600 g / cm or more. Thereby, since the adhesiveness of a conductor layer and a fluororesin layer improves more, the fall of the transmission rate and increase of transmission resistance by peeling with a dielectric material layer and a conductor layer can be suppressed effectively.

  The fluororesin layer may be chemically bonded to the intermediate layer. Thereby, since the adhesiveness of a fluororesin layer and an intermediate | middle layer is improving, peeling with a fluororesin layer and an intermediate | middle layer does not arise easily.

  The apparent dielectric constant of the dielectric layer is preferably 1.2 or more and 2.6 or less. Thereby, desired electrical performance can be easily and reliably exhibited as the entire dielectric layer.

  It is preferable that a rust-preventing layer containing a silane coupling agent is formed at the interface between the conductor layer and the dielectric layer, and the silane coupling agent and the fluororesin are chemically bonded. As a result, the dielectric layer and the conductor layer can be easily and reliably bonded with a desired adhesive force.

  The peel adhesion strength between the rust preventive layer and the epoxy resin when the conductor layer is removed and an epoxy resin is applied to the surface of the rust preventive layer on which the conductor layer is laminated is cured to 1 N / cm. The above is preferable. Thus, peeling between a rust prevention layer, a fluororesin layer, a coverlay, etc. hardly arises by making peeling adhesive strength of a rust prevention layer and an epoxy resin into the above-mentioned minimum or more.

  A void or a foam layer may be formed in at least one of the interface between the fluororesin layer, the intermediate layer, the conductor layer and the dielectric layer, or the interface between the fluororesin layer and the intermediate layer. Thus, the presence of the voids or the foamed layer can reduce the dielectric constant as a whole.

  The fluororesin is cross-linked, and the chemical bond between the fluororesin layer and the conductor layer is preferably performed by irradiation with ionizing radiation. That is, it is possible to employ a chemical bond between the fluororesin layer and the conductor layer by a reaction with a thermal radical in a vacuum, but it is preferable because the reaction is accelerated by the chemical bond by irradiation with ionizing radiation. Thus, the adhesive force between the fluororesin layer and the conductor layer can be easily and reliably improved (chemical bond) by irradiation with ionizing radiation.

  The intermediate layer preferably contains organic fibers, and the tensile elongation of the organic fibers is preferably 0.5% or more. Thus, the said intermediate | middle layer is comprised with the organic fiber whose tensile elongation is 0.5% or more, and the softness | flexibility and intensity | strength of a dielectric material layer improve.

The invention made to solve the above problems is
A wiring material in which a conductor layer is laminated on at least one surface of a dielectric layer,
The dielectric layer includes at least an intermediate layer and a pair of fluororesin layers laminated on both sides of the intermediate layer,
The ratio of the average thickness of the intermediate layer to the total average thickness of the pair of fluororesin layers is 0.001 or more and 30 or less,
The relative dielectric constant of the intermediate layer is 1.2 or more and 10 or less,
The linear expansion coefficient of the intermediate layer is −1 × 10 ⁻⁴ / ° C. or more and 5 × 10 ⁻⁵ / ° C. or less,
The wiring material has an adhesive force between the fluororesin layer and the conductor layer of 300 g / cm or more.

  In the wiring material, the dielectric layer includes a pair of fluororesin layers and an intermediate layer having a specific dielectric constant within a certain range, and the ratio of the average thickness of the intermediate layer to the total average thickness of the pair of fluororesin layers is within the above range. Therefore, desired electrical performance as the entire dielectric layer can be exhibited, and therefore, transmission speed can be improved and transmission loss can be suppressed. Moreover, since the thermal expansion coefficient of the intermediate layer is within the above range, when the wiring material is heated, the thermal expansion of the entire dielectric layer can be suppressed by the intermediate layer, and thus warpage due to heating is generated. Can be suppressed. Furthermore, since the wiring material has an adhesive force between the fluororesin layer and the conductor layer within the above range, and the adhesion between the two is improved, the dielectric layer and the conductor layer are unlikely to peel off. It is difficult to cause a decrease in transmission speed and an increase in transmission resistance due to peeling between the dielectric layer and the conductor layer.

  The “linear expansion coefficient” is a rate at which the length of an object expands when the temperature rises by 1 ° C., and is an average value from 20 ° C. to 150 ° C., and is measured by a thermomechanical analyzer (TMA) or the like. be able to. “Adhesive strength” means the peel strength measured according to JIS C6481. The “ten-point average roughness (Rz)” is a value measured according to JIS B 0601-1994, the evaluation length (l) is 3.2 mm, and the cutoff value (λc) is 0.8 mm. It was. The “apparent relative dielectric constant of the dielectric layer” means the ratio of the composite dielectric constant to the vacuum dielectric constant when the dielectric layer is determined as one medium. “Tensile elongation” means the elongation measured in accordance with JIS-L1013 (2010).

  As described above, the high-frequency printed wiring board and wiring material of the present invention sufficiently suppress the occurrence of warp when heated, and reduce transmission delay and transmission loss.

FIG. 1 is a schematic end view showing a high-frequency printed wiring board according to an embodiment of the present invention. 2A and 2B are schematic end views showing the manufacturing process of the printed wiring board for high frequency shown in FIG. 1. FIG. 2A shows a state in which a conductor layer and a dielectric layer are laminated, and FIG. 2B shows that the dielectric layer is irradiated with ionizing radiation. Indicates the state to be performed. FIG. 3 is a graph showing the transmission loss for each frequency for the high-frequency printed wiring board of Example 1 in comparison with Comparative Example 2 and Comparative Example 4 (the horizontal axis is frequency and the vertical axis is transmission). Loss). FIG. 4 is a graph showing the transmission loss for each frequency for the high-frequency printed wiring board of Example 2 compared to Comparative Example 2 and Comparative Example 4 (the horizontal axis is frequency and the vertical axis is transmission). Loss). FIG. 5 is a graph showing the transmission loss for each frequency for the high-frequency printed wiring board of Example 3 in comparison with Comparative Example 2 and Comparative Example 4 (the horizontal axis is frequency and the vertical axis is transmission). Loss).

  Hereinafter, embodiments of a printed wiring board for high frequency according to the present invention will be described in detail with reference to the drawings.

[High frequency printed wiring board]
The high-frequency printed wiring board 1 shown in FIG. 1 has a dielectric layer 3 and a pair of conductor layers 2 and 4 laminated on both surfaces of the dielectric layer 3. The high-frequency printed wiring board 1 is used as a flexible printed wiring board, for example.

  One (surface side) conductor layer 2 of the pair of conductor layers 2 and 4 constitutes a wiring pattern having a wiring 2a. The other conductor layer 4 constitutes a base layer on which the dielectric layer 3 is laminated on one surface (front surface). The conductor layers 2 and 4 are made of metal, and are generally made of copper.

(Wiring pattern)
The wiring pattern 2 has a plurality of wirings 2 a, and each wiring 2 a is appropriately set according to the specifications of the high-frequency printed wiring board 1. The wiring pattern 2 can be formed by a technique such as etching or cutting of a metal film or printing. In addition, it is preferable that the wiring 2a has a rust prevention layer (illustration omitted) formed in the interface with the dielectric material layer 3, and this rust prevention layer is good to contain a silane coupling agent. Further, the silane coupling agent of the rust preventive layer is preferably chemically bonded to the fluororesin of the dielectric layer 3. This rust preventive layer can be formed by surface treatment with a silane coupling agent before chemical bonding with the dielectric layer 3 as will be described later.

  The impedance of the circuit constituted by the wiring pattern 2 is appropriately set according to the specifications of the high-frequency printed wiring board 1 and can be, for example, 10Ω or more and 100Ω or less, or 30Ω or more and 80Ω or less. it can.

  The average thickness of the wiring 2a is preferably 1 μm to 2000 μm, more preferably 5 μm to 50 μm, and still more preferably 10 μm to 30 μm. When the average thickness of the wiring 2a is within the above range, the work of forming the wiring 2a is less likely to be complicated, and a desired impedance can be easily obtained.

  The transmission loss of the wiring pattern 2 at a frequency of 10 GHz is preferably 0.230 dB / cm or less, and more preferably 0.228 dB / cm or less. Thereby, it can use suitably for transmission of a high frequency area | region.

(Base layer)
The base layer 4 is a layer composed of a metal layer disposed over the entire back surface of the dielectric layer 3 as described above. The base layer 4 is used as a wiring pattern different from the ground or the wiring pattern 2, for example. The average thickness of the base layer 4 is preferably 1 μm or more and 2000 μm or less, and more preferably 10 μm or more and 300 μm or less. Thereby, the base layer 4 has sufficient strength in forming the dielectric layer 3, and the skin effect can be used with an appropriate thickness.

  The surface of the base layer 4 (interface with the dielectric layer 3) is not subjected to roughening treatment or primer treatment, and the dielectric layer 3 (fluororesin layer 3b) is irradiated with ionizing radiation or heated as described later. It is chemically bonded to the surface. Further, the ten-point average roughness (Rz) of the surface of the base layer 4 can be 4.0 μm or less, for example, but is preferably 2.0 μm or less. By setting the surface roughness of the base layer 4 in this way, a suitable transmission speed and transmission loss can be obtained. Note that the back surface (and the front surface) of the wiring pattern 2 is also preferably rough as described above, whereby a suitable transmission speed and transmission loss can be obtained. Here, the “average arithmetic roughness (Ra)” is a value measured according to JIS B 0601-1994, the evaluation length (l) is 3.2 mm, and the cutoff value (λc ) Was set to 0.8 mm.

(Dielectric layer)
The dielectric layer 3 has a three-layer structure including an intermediate layer 3a and a pair of fluororesin layers 3b laminated on both surfaces of the intermediate layer 3a. The fluororesin layer 3b is a layer mainly composed of a fluororesin. Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetrafluoroethylene copolymer. A polymer (ETFE), polyvinylidene fluoride (PVdF), etc. can be mentioned, These can be used individually or in mixture of 2 or more types.

  In order to prevent warpage and improve dimensional stability, a filler, cloth, or film may be inserted or mixed into the fluororesin layer 3b. Moreover, in order to give coloring, heat dissipation, or reflectivity, a filler and an additive can also be mixed. Further, foamability may be imparted, and porosity may be imparted by stretching or extrusion molding using a mold.

  The fluororesin of the fluororesin layer 3b is preferably crosslinked, and specifically, carbon atoms in the main chain of the fluororesin polymer are covalently bonded. By cross-linking the fluororesin, deformation at the reflow mounting temperature (about 260 ° C.) is suppressed, so that a highly accurate substrate can be obtained. Further, it is presumed that the fluororesin of the fluororesin layer 3b and the conductor layer are directly connected, that is, the fluororesin is chemically bonded to the material of the base layer 4. Specifically, the carbon atoms of the main chain of the fluororesin polymer and the atoms present on the surface of the base layer 4 are covalently bonded. As a method of cross-linking the fluororesin of the fluororesin layer 3b and further chemically bonding with the base layer 4, it is carried out by generating fluorine radicals by, for example, a method of irradiating ionizing radiation in the molten state of oxygen-free and fluororesin. it can. Moreover, it is estimated that the fluororesin of the fluororesin layer 3b is chemically bonded to the front and back surfaces of the wiring pattern 2. In addition, about the irradiation method of the said ionizing radiation, it explains in full detail in description of the manufacturing method of the said printed wiring board 1 for high frequency mentioned later.

  In addition, as a minimum of the irradiation amount of the ionizing radiation with respect to the fluororesin of the fluororesin layer 3b, 0.1 kGy is preferable and 1 kGy is more preferable. On the other hand, the upper limit of the irradiation dose is more preferably 900 KGy. When the irradiation dose is less than the lower limit, sufficient bonding strength with the conductor of the dielectric layer 3 cannot be obtained. Conversely, when the irradiation dose exceeds the upper limit, the decomposition reaction of the fluororesin (competition with crosslinking) There is a risk that strength will decrease due to (reaction) and foaming may occur at the interface between the copper foil and the resin.

  The relative dielectric constant of the fluororesin layer 3b is preferably 1.2 or more and 2.7 or less, and more preferably 1.4 or more and 2.5 or less. If this relative dielectric constant is less than the above lower limit value, the circuit width of copper may become too wide. On the other hand, when the relative dielectric constant exceeds the above upper limit, the dielectric loss tangent increases, and there is a possibility that the transmission loss cannot be sufficiently reduced, and a sufficient transmission speed may not be obtained. Moreover, since it is necessary to make the circuit width 50 μm or less from impedance matching, there is a possibility that mass production cannot be stably performed.

The linear expansion coefficient of the fluororesin layer 3b is 9 × 10 ⁻⁵ / ° C. The linear expansion coefficient of the fluororesin layer 3b is preferably 2 × 10 ⁻⁵ / ° C. or more and 1.2 × 10 ⁻⁴ / ° C. or less. If the linear expansion coefficient of the fluororesin layer 3b is less than the lower limit, the fluororesin layer 3b itself may be expensive. On the other hand, if the linear expansion coefficient of the fluororesin layer 3b exceeds the above upper limit value, the heated fluororesin layer 3b expands excessively, and thus there is a possibility that the occurrence of warpage of the high-frequency printed wiring board 1 cannot be accurately prevented. Arise.

  The total average thickness of the fluororesin layer 3b is preferably 0.5 μm or more and 1 mm or less, more preferably 1 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. If the total average thickness of the fluororesin layer 3b is less than the above lower limit value, the dielectric loss tangent may be increased and the transmission loss may not be sufficiently reduced, and a sufficient transmission rate may not be obtained. The formation of the layer 3b may be complicated. On the other hand, if the total average thickness of the fluororesin layer 3b exceeds the above upper limit value, the dielectric layer 3 becomes unnecessarily thick, which may violate the demand for thinning of the high-frequency printed wiring board 1 and the dielectric layer. 3 may increase the material cost, and the dielectric layer 3 may lack flexibility when flexibility is required. The total average thickness of the fluororesin layer 3b means a value obtained by adding the average thickness of each fluororesin layer 3b.

  The pair of fluororesin layers 3b preferably have the same thickness. Specifically, the ratio of the average thickness of the other fluororesin layer 3b to the average thickness of one fluororesin layer 3b is 0.9 or more and 1.1. The following is preferable. That is, when the thicknesses of the fluororesin layers 3b are greatly different from each other, there is a risk of warping due to thermal expansion of the fluororesin layer 3b, and the thicknesses of the fluororesin layers 3b are substantially equal as described above. Such problems can be suppressed.

  As the lower limit of the peel adhesion strength between the rust preventive layer and the epoxy resin after curing the epoxy resin, the epoxy resin is applied to the surface of the rust preventive layer on which the conductor layer is laminated after the conductor layer is removed. Is preferably 1 N / cm, more preferably 1.5 N / cm, and even more preferably 2 N / cm. When the peeling adhesion strength is less than the lower limit, peeling between the rust preventive layer and the fluororesin layer 3b, the coverlay, or the like may easily occur.

  The intermediate layer 3a is not particularly limited as long as the linear expansion coefficient is smaller than that of the fluororesin layer 3b. However, the insulation layer, the heat resistance that does not melt and flow at the melting point of the fluororesin, and the fluororesin It is desirable to have tensile strength equal to or higher than that, corrosion resistance, and linear expansion coefficient described later. The intermediate layer 3a is made of, for example, a glass cloth in which glass is formed into a cloth shape, a fluororesin-containing glass cloth in which such a glass cloth is impregnated with a fluororesin, metal, ceramics, alumina, polytetrafluoroethylene (PTFE), PEEK, Resin cloth in which heat-resistant fibers such as PI and aramid are formed in a cloth or non-woven fabric, or polytetrafluoroethylene (PTFE), LCP (type I), PI, PAI, PBI, PEEK, PTFE, PFA, thermosetting resin, cross-linking It can be composed of a heat-resistant film mainly composed of a resin or the like. In addition, these heat resistant resins and heat resistant films have a melting point (or heat distortion temperature) equal to or higher than the temperature of the step of bonding the fluororesin and the conductor. As a cloth weaving method, a plain weave is preferable for thinning the intermediate layer 3a, but a twill weave or a satin weave is preferable for bending applications. In addition, a known weaving method can be applied.

The density of the glass fiber of the glass cloth is preferably 1 g / m ³ or more and 5 g / m ³ or more, more preferably 2 g / m ³ or more and 3 g / m ³ or more. Moreover, as tensile strength of the said glass fiber, 1 GPa or more and 10 GPa or less are preferable, and 2 GPa or more and 5 GPa or less are more preferable. Moreover, as a tensile elasticity modulus of the said glass fiber, 10 GPa or more and 200 GPa or less are preferable, and 50 GPa or more and 100 GPa or less are more preferable. Furthermore, the maximum elongation of the glass fiber is preferably 1% or more and 20% or less, and more preferably 3% or more and 10% or less. Moreover, as a softening point of the said fiber, 700 to 1200 degreeC is preferable, and 800 to 1000 degreeC is more preferable. When the glass fiber has the above-described properties, the intermediate layer 3a can suitably exhibit a desired function. Even when a glass cloth is used in the present invention, it is not limited to the above numerical range.

  The fibers constituting the intermediate layer 3a have a tensile elongation of 0.5% from the viewpoint of imparting flexibility to the high-frequency printed wiring board 1 and from the viewpoint of bending and using the high-frequency printed wiring board 1. The above organic fibers are preferable, and LCP fibers, aramid fibers, and PEEK fibers are more preferable. In particular, LCP fibers are more preferable because of their low water absorption, dielectric constant, and dielectric loss tangent. Moreover, as a minimum of the said tensile elongation, 0.5% is preferable, 1.5% is more preferable, and 2% is further more preferable. When the tensile elongation is less than the above lower limit, the wiring 2a may be broken due to the breakage of the organic fiber, or the high-frequency printed wiring board 1 may be damaged. In addition, as a method of weaving the organic fiber, a known method such as plain weave or nonwoven fabric can be used.

  The relative dielectric constant of the intermediate layer 3a is, for example, about 6.8, and specifically 1.2 or more and 10 or less. Here, the relative dielectric constant of the intermediate layer 3a is preferably 1.5 or more and 6 or less, more preferably 1.8 or more and 5 or less. In order to reduce the relative dielectric constant of the intermediate layer 3a, a method of foaming the intermediate layer 3a is also conceivable. However, in this case, the rigidity of the intermediate layer 3a is insufficient, and a sufficient effect against warping may not be obtained. In addition, if the relative dielectric constant is less than the lower limit, the intermediate layer 3a may be expensive. On the other hand, when the relative dielectric constant exceeds the above upper limit value, the dielectric loss tangent becomes large and there is a possibility that the transmission loss cannot be sufficiently reduced, and there is a possibility that a sufficient transmission speed cannot be obtained.

  The apparent relative dielectric constant of the dielectric layer 3 (ratio of the dielectric constant when the pair of fluororesin layers 3b and the intermediate layer 3a therebetween is regarded as one medium and the dielectric constant of vacuum) is 1.2. It is preferably 2.6 or less, more preferably 1.4 or more and 2.4 or less, and further preferably 1.6 or more and 2.3 or less. In order to make the apparent relative dielectric constant less than the lower limit value, it is necessary to make the intermediate layer 3a thin or reduce the relative dielectric constant of the intermediate layer 3a. is there. On the other hand, when the apparent relative dielectric constant exceeds the upper limit, the dielectric loss tangent becomes large and there is a possibility that the transmission loss cannot be sufficiently reduced, and there is a possibility that a sufficient transmission speed cannot be obtained.

The linear expansion coefficient of the intermediate layer 3a is −1 × 10 ⁻⁴ / ° C. or more and 5 × 10 ⁻⁵ / ° C., preferably 0 / ° C. or more and 5 × 10 ⁻⁵ / ° C. or less, and 0 / ° C. or more and 1 ^X10 < ^-5 > / degrees C or less is more preferable. When the linear expansion coefficient of the intermediate layer 3a is less than the lower limit, the intermediate layer 3a itself may be expensive. On the other hand, if the linear expansion coefficient of the intermediate layer 3a exceeds the above upper limit, there is a possibility that the warpage of the high-frequency printed wiring board 1 due to the thermal expansion of the intermediate layer 3a cannot be accurately prevented.

  Moreover, as ratio of the linear expansion coefficient of the intermediate | middle layer 3a with respect to the linear expansion coefficient of the said fluororesin layer 3b, 0.95 or less is preferable and 0.1 or less is more preferable. If the ratio of the linear expansion coefficient between the fluororesin layer 3b and the intermediate layer 3a exceeds the upper limit, the effect of preventing the warp of the high-frequency printed wiring board 1 by the intermediate layer 3a may not be sufficiently exhibited. is there. In addition, the minimum of the ratio of the linear expansion coefficient of the intermediate | middle layer 3a with respect to the linear expansion coefficient of the fluororesin layer 3b is not specifically limited, For example, the said ratio is good to set it as 0.001 or more from a viewpoint of cost increase prevention.

  The average thickness of the intermediate layer 3a is preferably 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 20 μm or less. If the average thickness of the intermediate layer 3a is less than the lower limit, the effect of preventing the warpage of the high-frequency printed wiring board 1 by the intermediate layer 3a may not be sufficiently exhibited. On the other hand, if the average thickness of the intermediate layer 3a exceeds the above upper limit value, the dielectric layer 3 becomes unnecessarily thick, which may violate the demand for thinning the printed wiring board 1 for high frequency, and the material of the dielectric layer 3 The cost may increase, and the dielectric layer 3 may lack flexibility when flexibility is required. The intermediate layer can be provided with a plurality of layers in the dielectric layer. Moreover, it can also be used combining the intermediate | middle layer which changed thickness and kind. In addition, the dielectric constant can be lowered by providing air or voids in the intermediate layer and the fluororesin layer, the interface between the intermediate layer and the fluororesin layer, or the interface between the dielectric layer and the conductor layer. . The air and void may be closed cells or open cells, but it is desirable that the air and voids exist uniformly in the circuit or the size does not affect the circuit.

  The ratio of the total average thickness of the intermediate layer 3a to the total average thickness of the fluororesin layer 3b is 0.001 or more and 30 or less. The ratio of the average thickness of the intermediate layer 3a to the total average thickness of the pair of fluororesin layers 3b is preferably 0.1 or more and 2 or less, more preferably 0.2 or more and 0.5 or less. If the ratio of the average thickness of the fluororesin layer 3b and the intermediate layer 3a is less than the lower limit value, the intermediate layer 3a becomes too thin, and the intermediate layer 3a prevents the high-frequency printed wiring board 1 from warping. There is a possibility that the effect is not fully exhibited. On the other hand, if the ratio exceeds the upper limit, the intermediate layer 3a may be too thick, the dielectric layer 3 may be unnecessarily thick, the material cost of the dielectric layer 3 may increase, and the flexibility There is a possibility that the dielectric layer 3 lacks flexibility in the case where the above is required.

  The intermediate layer 3a is preferably chemically bonded to the fluororesin of the fluororesin layer 3b. Specifically, the carbon atoms in the main chain of the fluororesin polymer and the atoms present on the surface of the intermediate layer 3a are covalently bonded. As a method of chemically bonding the fluororesin of the fluororesin layer 3b and the intermediate layer 3a, for example, a method of irradiating ionizing radiation in the molten state of oxygen-free and fluororesin as described above can be used. This will be described later.

[Production method]
The high-frequency printed wiring board 1 is not particularly limited as long as the above-described printed wiring board can be formed, but can be easily and reliably manufactured by a manufacturing method including the following steps.
(1) Step of laminating the dielectric layer 3 and the wiring pattern 2 on the base layer 4 (2) Step of irradiating the dielectric layer 3 with ionizing radiation

<(1) Lamination process>
The lamination step is a step of laminating the dielectric layer sheet 3 constituting the dielectric layer 3 and the wiring pattern 2 on the surface of the base layer 4 as shown in FIG. Here, the dielectric layer sheet 3 has a three-layer structure including a pair of fluororesin layers 3b and an intermediate layer 3a disposed between the pair of fluororesin layers 3b. The wiring pattern 2 is formed in a desired shape by the above-described method. Furthermore, the dielectric layer sheet 3 includes a method of laminating the layers 3a and 3b by adhesion of an adhesive, a method of laminating the fluororesin layer 3b on the intermediate layer 3a while extruding, a method of laminating the layers 3a and 3b, and the like. Formed by.

<(2) Irradiation process>
In the irradiation step, as shown in FIG. 2B, at least the outer surface (front surface and back surface) of the dielectric layer sheet 3 is irradiated with ionizing radiation, whereby the dielectric layer 3 and the conductor layer (base layer 4 and The wiring pattern 2) is joined.

  At the time of this joining, the laminated body of the base layer 4, the dielectric layer sheet 3 and the wiring pattern 2 is placed in an oxygen-free atmosphere, specifically, an atmosphere having an oxygen concentration of 100 ppm or less, and the outer surface of the dielectric layer sheet 3 ( With the fluororesin on the front and back surfaces melted, the laminate is irradiated with ionizing radiation from the front side to crosslink the fluororesin and further chemically bond with the wiring pattern 2 and the base layer 4.

  As the oxygen-free atmosphere, the oxygen concentration is more preferably 5 ppm or less. If the oxygen concentration is high, the main chain of the fluororesin may be broken by irradiation with ionizing radiation. The temperature at which the fluororesin is melted is preferably a temperature that is 0 ° C. or more and less than 30 ° C. higher than the melting point of the fluororesin. When the fluororesin is heated to a temperature higher than the melting point by 30 ° C. or more, the thermal decomposition of the fluororesin is promoted and the material properties may be deteriorated. As a method for reducing the oxygen concentration, there is a method such as vacuum using an inert gas such as nitrogen.

  As said ionizing radiation, a gamma ray, an electron beam, an X-ray, a neutron beam, a high energy ion beam etc. can be used, for example. The irradiation dose of ionizing radiation is preferably 0.01 kGy or more and 1000 kGy or less, and more preferably 1 kGy or more and 500 kGy or less. When the irradiation dose is less than the above lower limit, the crosslinking reaction of the fluororesin may not proceed sufficiently. On the other hand, when the above upper limit is exceeded, the fluororesin may be easily decomposed.

<(3) Wiring pattern forming step>
Furthermore, the manufacturing method of the said printed circuit board 1 for high frequency has the process (wiring pattern formation process) of forming the conductor layer of a predetermined pattern on the surface of the dielectric material layer 3 before the said irradiation process. This forming method is not particularly limited, and for example, patterning may be employed by etching after laminating metal foils, laminating punched metal foils, arranging metal wires, painting or printing metal particles, and the like. These metal wires are surface-treated with a silane coupling agent and then chemically bonded to the fluororesin (dielectric layer), whereby the conductor layer and the fluororesin layer are chemically bonded, and the surface roughness is 4 μm or less. Even a simple interface can be firmly bonded. As the silane coupling agent, a compound containing an S atom or an N atom is preferable because of its strong adhesive force.

[advantage]
Since the high-frequency printed wiring board 1 is irradiated with ionizing radiation in a predetermined environment, the fluororesin of the dielectric layer 3 is chemically bonded to the conductor layer (base layer 4 and / or wiring pattern 2). Since the adhesion between the body layer 3 and the conductor layers 2 and 4 is improved and the adhesive strength is excellent, for example, the dielectric layer 3 and the conductor layers 2 and 4 are hardly separated during circuit formation. It is difficult to cause a decrease in transmission speed and an increase in transmission resistance due to separation between the layer 3 and the conductor layers 2 and 4.

  The dielectric layer 3 has a pair of fluororesin layers 3b and an intermediate layer 3a having a specific dielectric constant within a certain range, and the ratio of the average thickness of the intermediate layer 3a to the total average thickness of the pair of fluororesin layers 3b is as described above. Since it is within the range, desired electrical performance as the entire dielectric layer 3 can be exhibited, and therefore, transmission speed can be improved and transmission loss can be suppressed.

  Furthermore, since the thermal expansion coefficient of the intermediate layer 3a is within a certain range, the thermal expansion of the dielectric layer 3 as a whole is suppressed by the intermediate layer 3a when the high-frequency printed wiring board 1 is heated during reflow or the like. For this reason, generation | occurrence | production of the curvature by heating can be suppressed.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  That is, in the said embodiment, although the thing of the three-layer structure of the dielectric material layer 3 and a pair of conductor layers 2 and 4 was demonstrated, this invention is not limited to this. For example, a five-layer structure including a pair of dielectric layers, a conductor layer between the pair of dielectric layers, and a pair of conductor layers respectively disposed on the outer surfaces of the pair of dielectric layers, or a further multilayer structure The high-frequency printed wiring board is also within the scope of the claims. Further, the high-frequency printed wiring board in the state in which the wiring pattern of the above embodiment is not formed, that is, in the state of the two-layer structure of the base layer and the dielectric layer is also within the scope of the claims.

  Moreover, in the said embodiment, although the thing which has flexibility was mainly demonstrated, the said printed wiring board for high frequencies may not have flexibility.

  Furthermore, although the above embodiment has been described by taking a high-frequency printed wiring board as an example, the present invention is applied to a wiring material such as a high-frequency wiring material such as a high-frequency flat cable, a high-frequency electric wire, and a high-frequency antenna. The wiring material according to the present invention can achieve the advantages described above by adopting the configuration of the above embodiment.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Overview of high-frequency printed wiring boards]
A resin dielectric layer is provided on the surface of the base layer made of a copper film, and a single band-like wiring is provided on the surface of the dielectric layer, whereby the high frequencies of Examples 1 and 2 and Comparative Examples 1 to 5 are provided. A printed wiring board is obtained. A copper film having an average thickness of 10 μm to 50 μm and a surface roughness of Rz 0.6 μm is used. Moreover, the antirust process layer is given to the copper film. The copper film and the dielectric layer are bonded with a strength of 300 g / cm or more for chemical bonding, and do not peel even when bent. Further, the copper film and the dielectric layer did not peel or swell even when heated at 260 ° C. or higher for 1 minute. For this reason, it judged that it had the heat resistance which can be surface-mounted.

[Examples 1 to 5]
In Examples 1 to 5, the dielectric layer forming material is bonded to the surface of the copper film in a laminated state. The adhesion process can be performed using a known hot press. The bonding step is preferably performed by vacuum pressing under a low oxygen concentration, for example, in a nitrogen atmosphere. By performing the bonding step under a low oxygen concentration, it is possible to suppress oxidation of one surface (bonding surface with the fluororesin) of the copper film and suppress a decrease in adhesion.

  The heating temperature in the bonding step is preferably not less than the crystal melting point of the fluororesin, more preferably not less than 30 ° C. higher than the crystal melting point, and more preferably not less than 50 ° C. higher than the crystal melting point. For example, when the main component of the fluororesin portion is FEP, since the crystal melting point of this FEP is about 270 ° C., the heating temperature is preferably 270 ° C. or higher, more preferably 300 ° C. or higher, and further preferably 320 ° C. or higher. By heating the fluororesin portion at such a heating temperature, radicals of the fluororesin can be effectively generated. However, if the heating temperature is too high, the fluororesin itself may be deteriorated, so the upper limit of the heating temperature is preferably 600 ° C. or less, more preferably 500 ° C. or less.

In addition to the above-mentioned pressure heating, other known radical generation methods such as electron beam irradiation may be used in combination. Examples of electron beam irradiation include γ-ray irradiation treatment. By using electron beam irradiation or the like in combination, radicals of the fluororesin can be generated more effectively, so that the reliability of adhesion between the one surface of the synthetic resin portion and the copper film can be further increased. This dielectric layer has a three-layer structure in which a fluororesin layer is laminated on both sides of the intermediate layer, and a glass cloth was used as the intermediate layer. The glass cloth was defined by IPC style. As the fiber of the glass cloth, E glass having a diameter of 4 μm was used. The fiber has a linear expansion coefficient of 5.6 × 10 ⁻⁵ / ° C., a tensile strength of 3.2 GPa, a tensile elastic modulus of 75 GPa, and a maximum elongation of 4.8%. The surface is treated with aminosilane. This glass cloth is not impregnated with a fluororesin. The fluororesin layer is a layer whose main component is tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The composite dielectric constant εr (apparent relative dielectric constant) of this dielectric layer is 2.25.

  In Example 1, a glass cloth # 1017 having an average thickness of 13 μm was used as an intermediate layer, and a fluororesin layer having an average thickness of 25 μm was laminated on both sides of the intermediate layer, followed by hot pressing so that the fluororesin was contained in the glass cloth. In order to penetrate, the entire thickness shrunk, and a dielectric layer having an average thickness of 48 μm was obtained. Note that a three-layer structure is obtained in a state in which a part of the surface layer of the intermediate layer (3 μm in total) is impregnated with the fluororesin layer. The copper foil is an electrolytic copper foil (thickness: 18 μm), the surface roughness is Rz 0.6 μm, and the surface is formed with a rust prevention layer with a thickness of 1 μm or less composed of cobalt, silane coupling agent, etc. Yes. When the cross section after pressing was observed, the voids in the glass cloth were filled with fluororesin.

  In Example 2, a glass cloth # 1015 having an average thickness of 15 μm is used as an intermediate layer, and a fluororesin layer is laminated on both surfaces of the intermediate layer so as to have an average thickness of 20 μm, thereby obtaining a dielectric layer having an average thickness of 50 μm. It was. Note that a three-layer structure is obtained in a state in which a part of the surface layer of the intermediate layer (5 μm in total) is impregnated with the fluororesin layer.

  In Examples 1 and 2, when the average thickness of the wiring is 12 μm and the average width of the wiring is adjusted so that the impedance is 50Ω, the average width of the wiring is 69.7 μm.

  In Example 3, the intermediate layer and the interface between the intermediate layer and the fluororesin layer were bonded together while air was entrained to obtain a high-frequency printed wiring board. The void was a closed cell, and the maximum size was Φ50 μm or less. Further, after pressing, electron beam irradiation was performed at 10 kGy at oxygen of 100 ppm or less and 320 ° C.

  In Example 4, two intermediate layers were used and copper foil / glass cloth / fluorine resin / glass cloth / copper foil was pressed to obtain copper foil / fluorine resin / glass cloth / fluorine resin / glass cloth / fluorine resin. / A high-frequency printed wiring board having a copper foil configuration was prepared.

  In Example 5, a high-frequency printed wiring board was used in the same manner as in Example 1 except that an LCP nonwoven fabric having an average thickness of 14 μm and a maximum elongation of 2-3% (“Kuraray NP-6”) was used as the intermediate layer. A plate was made. When the cross section after pressing was observed, the voids in the LCP nonwoven fabric were filled with fluororesin (FEP).

[Comparative Examples 1-5]
In Comparative Example 1, a dielectric layer made of a fluororesin is used. In Comparative Examples 2 to 3, a dielectric layer made of a liquid crystal polymer (LCP) is used. In Comparative Examples 4 to 5, a polyimide dielectric layer is used. It was.

  The relative dielectric constant of the dielectric layer is 2.1 in Comparative Example 1, 3.0 in Comparative Examples 2 to 3, and 3.4 in Comparative Examples 4 to 5. The average thickness of the dielectric layer is 43 μm in Comparative Example 1, 25 μm in Comparative Example 2, 40 μm in Comparative Example 3, 25 μm in Comparative Example 4, and 40 μm in Comparative Example 5.

  When the average thickness of the wiring is 12 μm in Comparative Examples 1 to 5 and the average width of the wiring is adjusted so that the impedance is 50Ω, the average width of each wiring is 32.2 μm in Comparative Example 1 and 54.2 μm in Comparative Example 2. In Comparative Example 3, it is 90.6 μm, in Comparative Example 4 is 49.3 μm, and in Comparative Example 5 is 82.6 μm.

[Evaluation]
<Transmission loss and dimensional change>
About the said Examples 1-4 and the comparative examples 1-5, the transmission loss and dimensional change in frequency 10GHz and 15GHz are measured. This transmission loss is obtained by connecting Examples 1 to 4 and Comparative Examples 1 to 5 to a calibrated network analyzer and measuring the characteristics of S parameters S21 and S12. The dimensional change is measured by measuring the rate of change in the distance between holes marked between 10 cm by heating the entire surface of the single-sided copper foil of the double-sided substrate and heating at 150 ° C. for 30 minutes.

  As shown in Table 1, Examples 1-4 have smaller dimensional changes than those of Comparative Example 1, that is, less warpage when heated. Moreover, the transmission loss of Examples 1-4 is small compared with the thing of Comparative Examples 2-5. In addition, in FIGS. 3-5, the transmission loss according to the frequency was represented about Examples 1-3 and Comparative Examples 2 and 4. FIG. As is apparent from the graphs of FIGS. 3 to 5, the first to third embodiments have a smaller transmission loss than the comparative examples 2 and 4, and the difference in transmission loss particularly in the high frequency region is remarkable.

<Bending strength>
About the printed wiring board for high frequency of Example 2 and Example 5, bending strength was evaluated in the following procedures. The bending test was performed by repeatedly bending the high-frequency printed wiring boards of Example 2 and Example 5 under a load of 1 kg with a bending R of 0 μm and then returning to the original state. Similarly, a bending test was performed on the high-frequency printed wiring boards of Example 2 and Example 5 with a bending R of 0.2 μm. After folding, the folds and valleys of the bent part were observed using a microscope to examine whether the wiring was damaged.

  When the bend R was 0 μm, the mountain fold portion of the high-frequency printed wiring board of Example 2 was not damaged even after being bent 10 times, but the valley fold portion was damaged after being bent twice. On the other hand, the printed wiring board for high frequency of Example 5 was not damaged in any of the mountain fold and the valley fold after being bent 10 times.

  When the bending R is 0.2 μm, the mountain fold of the high-frequency printed wiring board of Example 2 is not damaged even after being bent 10 times, and the valley fold is not damaged after being bent 9 times. did. On the other hand, the printed wiring board for high frequency of Example 5 was not damaged in any of the mountain fold and the valley fold after being bent 10 times.

[Reference Example 1]
In Reference Example 1, an FEP sheet (“NF-0050” from Daikin Industries, Ltd.) having an average thickness of 50 μm, an average width of 10 mm, and an average length of 500 mm was used as the fluororesin layer. A copper foil having an average thickness of 18 μm and a surface roughness of 0.6 μm was used as the conductor layer. This copper foil is immersed in a mixture of aminosilane and ethanol (aminosilane concentration is 1% by mass) as a silane coupling agent, and then dried and heated at 120 ° C. to form a rust preventive layer having an average thickness of 30 nm. Formed on the outer surface. This copper foil and the fluororesin layer were thermocompression bonded to obtain a laminate of the copper foil and the fluororesin layer.

Next, the copper foil of the laminate was etched to form 25 wires having an average thickness of 18 μm, an average width of 100 μm, and an average pitch of 100 μm. In the etching, using an etchant containing iron chloride, the specific gravity of the etchant 1.31 g / cm ³ or more 1.33 g / cm ³ or less, free hydrochloric acid concentration of 0.1 mol / L or more 0.2 mol / L It controlled so that it might become the following, and immersed for 2 minutes at the temperature of 45 degreeC.

  Thereafter, a coverlay having an epoxy resin layer having an average thickness of 25 μm and a polyimide layer having an average thickness of 13 μm was laminated on the surfaces of the wiring and the fluororesin layer, whereby the evaluation substrate of Reference Example 1 was obtained.

[Reference Example 2]
Evaluation of Reference Example 2 was performed in the same manner as in the above Reference Example except that a PFA sheet (“AF-0050” from Daikin Industries, Ltd.) having an average thickness of 50 μm, an average width of 10 mm, and an average length of 500 mm was used as the fluororesin layer. A substrate was obtained.

[Evaluation]
<Adhesion reliability>
For the evaluation substrates of Reference Examples 1 and 2 above, peel adhesion after leaving for 100 hours in an environment of peel adhesive strength and relative humidity of 85% and temperature of 85 ° C. immediately after adhesion of the coverlay, copper foil and fluororesin layer. Each strength was measured. The peel adhesion strength between the coverlay and the copper wiring conforms to JIS-K6854-2 (1999). When the copper wiring and the fluororesin layer are made of a flexible adherend, the coverlay is made of a flexible adherend. In each case, two points were measured. The measurement results are shown in Table 2. Further, the rate of change in peel adhesive strength (represented by {(P2-P1) / P1} × 100, where P1 is the peel adhesive strength immediately after bonding and P2 is the peel adhesive strength after 100 hours). Values) are also shown in Table 2.

  As shown in Table 2, each of the evaluation substrates of Reference Examples 1 and 2 has a high peel adhesive strength of 1 N / cm or more, and the change rate of the peel adhesive strength in a high temperature and high humidity environment is also shown. Even in such an environment, the adhesive strength was difficult to decrease.

<Etching resistance>
[Reference Examples 3 and 4]
After forming the laminated body of a fluororesin layer and copper foil similarly to the said reference example 1, the laminated body of the antirust layer and the fluororesin layer was obtained by etching all the copper foil. A coverlay similar to that of Reference Example 1 was laminated on the surface of the laminate on the rust-preventing layer side to obtain an evaluation substrate of Reference Example 3. Further, an evaluation substrate of Reference Example 4 was obtained in the same manner as in Reference Example 3 except that the same fluororesin layer as in Reference Example 2 was used.

For the evaluation substrates of Reference Examples 3 and 4 above, the peel adhesion strength between the rust preventive layer and the cover lay immediately after the cover lay adhesion and the peel adhesion strength between the rust preventive layer and the cover lay after etching were measured, Rate of change of the peel adhesive strength (when the peel adhesive strength immediately after bonding is P1, and the peel adhesive strength after etching is P3, a value represented by {(P3-P1) / P1} × 100) Asked. The etching uses an etchant containing iron chloride, the specific gravity of the etchant 1.31 g / cm ³ or more 1.33 g / cm ³ or less, free hydrochloric acid concentration of 0.1 mol / L or more 0.2 mol / L It controlled so that it might become the following, and it carried out by immersing for 2 minutes at the temperature of 45 degreeC.

  In the above Reference Examples 3 and 4, the rate of change in peel adhesion strength was within ± 10%, indicating that the etching resistance of the anticorrosive layer was high. For this reason, in the etching within 45 minutes at 45 ° C. or less using the etching solution in the production of the high-frequency printed wiring board, the rust preventive layer of the reference example has little deterioration and is suitable for practical use.

<Water contact angle>
Moreover, about the laminated body of the rust prevention layer and fluororesin layer which were obtained by the procedure similar to the fluororesin layer used in the reference examples 1 and 2 and the said reference examples 3 and 4, the contact angle with respect to water was set to JIS-K6894 ( 2014). The water contact angle of the fluororesin layer (FEP) of Reference Example 1 is 114 ° (average of 4 points), and the water contact angle of the fluororesin layer (PFA) of Reference Example 2 is 115 ° (4 Average value of points). On the other hand, the water contact angle of the laminate in which the rust preventive layer was formed on the fluororesin layer was 60 ° to 80 °. Thus, it was shown that the hydrophilicity of the fluororesin is improved by the antirust layer. Therefore, the adhesiveness between the fluororesin layer and the epoxy resin can be improved by forming the rust preventive layer.

  As described above, since the high-frequency printed wiring board and wiring member of the present invention have high transmission speed and low transmission loss even in a high-frequency region, they can be suitably used for, for example, communication equipment using high frequency.

DESCRIPTION OF SYMBOLS 1 High frequency printed wiring board 2 Conductor layer 2a Wiring 3 Dielectric layer (dielectric layer sheet)
3a Intermediate layer 3b Fluororesin layer 4 Conductor layer

Claims (7)

A printed wiring board for high frequency in which a conductor layer is laminated on at least one surface of a dielectric layer,
The dielectric layer comprises at least an intermediate layer and a pair of fluororesin layers laminated on both surfaces of the intermediate layer,
The ratio of the total average thickness of the intermediate layer to the total average thickness of the fluororesin layer is 0.001 or more and 30 or less,
The relative dielectric constant of the intermediate layer is 1.2 or more and 10 or less,
The linear expansion coefficient of the intermediate layer is −1 × 10 ⁻⁴ / ° C. or more and 5 × 10 ⁻⁵ / ° C. or less,
The adhesive force between the fluororesin layer and the conductor layer is 600 g / cm or more,
The conductor layer has a ten-point average roughness (Rz) of 4 μm or less,
The fluororesin layer and the conductor layer are chemically bonded ,
A rust prevention layer containing a silane coupling agent is formed at the interface between the conductor layer and the dielectric layer, and the silane coupling agent and the fluororesin are chemically bonded.
When the conductor layer is removed and an epoxy resin is applied to the surface on which the conductor layer of the rust preventive layer is laminated and cured, the peel adhesion strength between the rust preventive layer and the epoxy resin is 1 N / cm or more And
The contact angle with water of the anticorrosion layer from which the conductor layer has been removed by the etching reaction is lowered by 20 ° or more compared to the contact angle with water measured when the silane coupling agent and the fluororesin are not chemically bonded. , high-frequency printed circuit board, characterized in der Rukoto 100 ° or less.   The printed wiring board for high frequency according to claim 1, wherein the fluororesin layer is chemically bonded to the intermediate layer.   The high-frequency printed wiring board according to claim 1 or 2, wherein an apparent relative dielectric constant of the dielectric layer is 1.2 or more and 2.6 or less. The fluororesin layer, an intermediate layer, at least one of the interface between the interface between the conductive layer and the dielectric layer, or a fluorine resin layer and the intermediate layer, according to claim 1, voids or foam layer is formed, according to claim 2 Or the printed wiring board for high frequencies of Claim 3 . The high-frequency printed wiring according to any one of claims 1 to 4 , wherein the fluororesin is cross-linked, and the chemical bond between the fluororesin layer and the conductor layer is performed by irradiation with ionizing radiation. Board. The high-frequency printed wiring board according to any one of claims 1 to 5 , wherein the intermediate layer includes an organic fiber, and the tensile elongation of the organic fiber is 0.5% or more. A wiring material in which a conductor layer is laminated on at least one surface of a dielectric layer,
The dielectric layer comprises at least an intermediate layer and a pair of fluororesin layers laminated on both surfaces of the intermediate layer,
The ratio of the total average thickness of the intermediate layer to the total average thickness of the fluororesin layer is 0.001 or more and 30 or less,
The relative dielectric constant of the intermediate layer is 1.2 or more and 10 or less,
The linear expansion coefficient of the intermediate layer is −1 × 10 ⁻⁴ / ° C. or more and 5 × 10 ⁻⁵ / ° C. or less,
The adhesive force between the fluororesin layer and the conductor layer is 600 g / cm or more,
The conductor layer has a ten-point average roughness (Rz) of 4 μm or less,
The fluororesin layer and the conductor layer are chemically bonded ,
A rust prevention layer containing a silane coupling agent is formed at the interface between the conductor layer and the dielectric layer, and the silane coupling agent and the fluororesin are chemically bonded.
When the conductor layer is removed and an epoxy resin is applied to the surface on which the conductor layer of the rust preventive layer is laminated and cured, the peel adhesion strength between the rust preventive layer and the epoxy resin is 1 N / cm or more And
The contact angle with water of the anticorrosion layer from which the conductor layer has been removed by the etching reaction is lowered by 20 ° or more compared to the contact angle with water measured when the silane coupling agent and the fluororesin are not chemically bonded. , wiring material, characterized in der Rukoto 100 ° or less.

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