JP2021171963A - Metal-laminated film and method for manufacturing the same - Google Patents

Abstract

To provide a metal-laminated film capable of improving transmission characteristics in a printed wiring board.SOLUTION: A metal layer is laminated on at least one surface of a liquid crystal polymer film, and a degree F of orientation of the liquid crystal polymer film at a central portion in a thickness direction is 0.31 or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a metal laminated film and a method for producing the same.

Conventionally, as a base material for producing a printed wiring board, a metal laminated film in which a metal layer such as copper foil is laminated on a rigid substrate such as a paper base material phenol resin or a polymer film such as a liquid crystal polymer film has been known. There is. In recent years, with the advent of the 5th generation mobile communication system (5G), a metal layer such as copper foil is laminated on a liquid crystal polymer film having low dielectric properties in order to improve the high frequency characteristics of the printed wiring board. The development of the metal laminated film is in progress.

As the metal laminated film, generally, one produced by using a thermal laminating method in which a metal foil having a roughened pressure-bonded surface is heat-bonded to a polymer film is known from the viewpoint of adhesion. For example, Patent Document 1 describes a high-frequency circuit board in which the molecular orientation degree SOR of the liquid crystal polymer film is 1.3 or less, and a rolled copper foil is heat-bonded to the liquid crystal polymer film by using a thermal laminating method. The manufactured high frequency circuit board is disclosed. Further, in Patent Document 2, the liquid crystal polymer film is heated to a temperature equal to or higher than the melting point by using a thermal laminating method while continuously supplying the liquid crystal polymer film and the copper foil in which the surface roughness Rz of the pressure-bonded surface is defined. A laminated board for a flexible printed wiring board manufactured by heat-pressing a copper foil to a liquid crystal polymer film is disclosed.

On the other hand, as a metal laminated film, the surface of the laminate is activated by removing oxides, stains, etc. by a method such as sputtering etching, and the surface of the activated laminate is brought into contact with the surface of another laminate. It is also known that it is produced by using surface-activated bonding, which is bonded by rolling and rolling. For example, Patent Document 3 describes a metal thin film surface and a metal foil surface activated by sputter etching in a metal thin film laminated film in which a metal thin film is formed on the surface of a polymer film as a metal laminated film for use in a flexible circuit substrate or the like. A multilayer metal laminated film produced by pressure welding is disclosed.

Japanese Unexamined Patent Publication No. 2000-269616 Japanese Patent No. 541165 Japanese Patent No. 4532713

When a metal layer is heat-bonded to a liquid crystal polymer film by using the thermal laminating method disclosed in Patent Documents 1 and 2, it is necessary to heat the liquid crystal polymer film to a temperature equal to or higher than the melting point. It is said that. Therefore, as a result of heating the liquid crystal polymer film near the melting point or above the melting point, the quality of the liquid crystal polymer film may be significantly deteriorated and its orientation may be greatly disturbed. As a result, the dielectric properties of the liquid crystal polymer film may be deteriorated, and the transmission characteristics of the printed wiring board made of the metal laminated film may be deteriorated.

On the other hand, in the multilayer metal laminated film disclosed in Patent Document 3, which is a metal laminated film produced by surface activation bonding, a liquid crystal polymer film is not used as the polymer film. Therefore, the printed wiring board produced from the printed wiring board has low transmission characteristics especially in a high frequency region (for example, 28 GHz).

Therefore, an object of the present invention is to provide a metal laminated film capable of improving the transmission characteristics of a printed wiring board and a method for producing the same.

As a result of diligent studies by the present inventors, when a liquid crystal polymer film is used as a polymer film of a metal laminated film, the metal laminated film is formed by bonding a metal layer to the liquid crystal polymer film by surface activation bonding. By producing the film, it was found that the disorder of the orientation of the liquid crystal polymer film could be suppressed and the above-mentioned problems could be solved, and the invention was completed. That is, the gist of the present invention is as follows.

(1) A metal laminated film in which a metal layer is laminated on at least one surface of the liquid crystal polymer film, and the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film is 0.31 or more.
(2) A metal layer is laminated on at least one surface of the liquid crystal polymer film, and the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film is the same as that of the liquid crystal polymer film before the metal layer is laminated. A metal laminated film having a degree of orientation F of 77% or more in the central portion in the thickness direction.
(3) The metal laminated film according to (1) or (2) above, wherein the average degree F of orientation F in the thickness direction of the liquid crystal polymer film is 0.31 or more.
(4) Any one of (1) to (3) above, wherein the dielectric loss tangent of the liquid crystal polymer film is less than 114% of the dielectric loss tangent of the liquid crystal polymer film before the metal layers are laminated. The metal laminated film described in 1.
(5) The metal laminated film according to any one of (1) to (4) above, wherein the bonding strength between the metal layer and the liquid crystal polymer film is 2.0 N / cm or more.
(6) The metal laminated film according to any one of (1) to (5) above, wherein the metal layer has a metal foil.
(7) The metal laminated film according to (6) above, wherein the metal layer further has an intermediate layer containing a metal between the liquid crystal polymer film and the metal foil.
(8) The intermediate layer is a metal selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver, and gold, or an alloy containing the metal. The metal laminated film according to (7) above, which comprises.
(9) The metal laminated film according to any one of (6) to (8) above, wherein the metal foil is a copper foil, a copper alloy foil, or a copper foil with a carrier.
(10) The method for producing a metal laminated film according to (7) above, wherein the liquid crystal polymer film and the metal foil are prepared (preparation step), and at least one surface of the liquid crystal polymer film contains a metal. A step of laminating the intermediate layer (intermediate layer laminating step), a step of activating the surface of the intermediate layer by sputter etching (activation step), and a step of activating the surface of the metal foil by sputter etching (activation). Step), a step of rolling and joining the intermediate layer and the activated surfaces of the metal foil at a reduction rate of 0 to 30% (rolling joining step), and the rolling-joined intermediate layer and the metal foil. A method for producing a metal laminated film, comprising a step (heat treatment step) of heat-treating the metal layer and the liquid crystal polymer film at a temperature of the melting point of the liquid crystal polymer film of −100 ° C. or higher and the melting point of −10 ° C. or lower.
(11) The method for producing a metal laminated film according to (10) above, wherein the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film after the heat treatment is 0.31 or more.
(12) The degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film after the heat treatment is 77% or more of the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film before the metal layers are laminated. The method for producing a metal laminated film according to the above (10) or (11).
(13) The dielectric loss tangent of the liquid crystal polymer film after the heat treatment is less than 114% of the dielectric loss tangent of the liquid crystal polymer film before the metal layers are laminated (10) to (12). ) The method for producing a metal laminated film according to any one of them.

According to the present invention, the transmission characteristics of the printed wiring board can be improved.

It is the schematic sectional drawing which shows an example of the metal laminated film of embodiment. It is schematic cross-sectional view which shows the main part of the example of the manufacturing method of the metal laminated film of embodiment. It is schematic cross-sectional view which shows the main part of the example of the manufacturing method of the metal laminated film of embodiment. It is the schematic which shows the measurement region of the degree of orientation F in the section of a liquid crystal polymer film. It is a graph which shows the degree of orientation F for each position of the measurement area in the untreated and the section of the liquid crystal polymer film of Example 1 and Comparative Example 2.

Hereinafter, embodiments relating to the metal laminated film of the present invention and the method for producing the same will be described.

A. Metal Laminated Film Here, an embodiment according to the metal laminated film of the present invention will be illustrated and described. FIG. 1 is a schematic cross-sectional view showing an example of the metal laminated film of the embodiment.

As shown in FIG. 1, in the metal laminated film 1A of this example, the metal layer 10 is laminated on one surface 20a of the liquid crystal polymer film 20. The metal layer 10 is a copper foil (metal) laminated on an intermediate layer 14 containing copper laminated on one surface 20a of the liquid crystal polymer film 20 and a surface 14a of the intermediate layer 14 opposite to the liquid crystal polymer film 20 side. It has a foil) 12.

The degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film 20 before the metal layer 10 is laminated is 0.4. On the other hand, in the metal laminated film 1A, the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film 20 is 0.31 or more, and the thickness of the liquid crystal polymer film 20 before the metal layer 10 is laminated. The degree of orientation F at the center of the direction is 77% or more. As a result, the dielectric loss tangent of the liquid crystal polymer film 20 is less than 114% of the dielectric loss tangent of the liquid crystal polymer film 20 before the metal layer 10 is laminated. Therefore, the transmission characteristics of the printed wiring board made of the metal laminated film 1A can be improved. Further, the bonding strength between the metal layer 10 and the liquid crystal polymer film 20 is 2.0 N / cm or more, and the adhesion between the metal layer 10 and the liquid crystal polymer film 20 is high. Therefore, it is possible to improve the reliability of the fine wiring of the printed wiring board produced from the metal laminated film 1A.

Therefore, according to the metal laminated film of the embodiment, the transmission characteristics of the printed wiring board can be improved as in the metal laminated film 1A of the above example. Further, when the bonding strength between the metal layer and the liquid crystal polymer film is 2.0 N / cm or more, it is possible to achieve both the transmission characteristics of the printed wiring board and the reliability of the fine wiring.

Subsequently, each configuration of the metal laminated film of the embodiment will be described in detail.

1. 1. Liquid crystal polymer film The degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film is 77% or more of the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film before the metal layers are laminated.

Here, the "liquid crystal polymer film" refers to a film made of an aromatic polyester resin having a basic structure such as parahydroxybenzoic acid, which exhibits the properties of a liquid crystal in a molten state.

Here, the "degree of orientation F" means the degree of molecular orientation in the MD (stretching direction of the film), and is calculated using the following method. First, a polarizer for infrared light is attached to a micro-infrared spectroscope (micro-FT-IR device) to obtain an infrared transmission spectrum and MD in the polarization direction parallel to the MD of the polymer film (here, a liquid crystal polymer film). Infrared transmission spectrum in the vertical polarization direction is measured. ^{Next, using the peaks of 1601 cm -1} in these infrared transmission spectra, the infrared dichroic ratio D (the intensity A‖ of the peak of ^{1601 cm -1 in} the infrared transmission spectrum in the polarization direction parallel to MD and perpendicular to MD. The ratio of the intensity A⊥ of the peak of ^{1601 cm -1 in} the infrared transmission spectrum in the parallel polarization direction) is obtained. The base line of the intensity of these peaks is set to a line connecting the 1618.9Cm ^-1 and 1572.4Cm ^-1 of the infrared transmission spectrum. Further, here, ^{the peak of 1601 cm -1 is} a peak that is attributed to the C = C expansion and contraction vibration of the benzene ring and has a transition moment parallel to the molecular chain. Next, the degree of orientation F is calculated from the infrared bicolor ratio D. The methods for calculating the infrared bicolor ratio D and the degree of orientation F are the formulas (1) and (2), respectively.

The “degree of orientation F at the center in the thickness direction” is, for example, an infrared dichroic ratio D in a measurement region located at the center in the thickness direction in a cross section (vertical cross section) perpendicular to the surface of the liquid crystal polymer film and parallel to the MD. Refers to the degree of orientation F calculated from the infrared bicolor ratio D measured in the measurement region. The measurement region is not particularly limited, and examples thereof include a rectangular region having an MD length of 100 μm and a length of 10 μm in the thickness direction shown in FIG.

The “liquid crystal polymer film before the metal layer is laminated” refers to the liquid crystal polymer film prepared in the preparatory step described in the item “B. Manufacturing method of metal laminated film 1. Preparation step” described later.

The degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film is not particularly limited as long as it is 77% or more of the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film before the metal layers are laminated, and the metal layer. It is preferable that the degree of orientation F in the central portion in the thickness direction of the liquid crystal polymer film before laminating is closer, but specifically, for example, it is 0.31 or more, more preferably 0.315 or more, and further. It is preferably 0.32 or more. This is because the transmission characteristics are particularly good.

The average degree of orientation F in the thickness direction of the liquid crystal polymer film is not particularly limited, and is preferably closer to the average degree of orientation F in the thickness direction of the liquid crystal polymer film before the metal layers are laminated, but the metal layers are laminated. It is preferable that the degree of orientation F in the thickness direction of the liquid crystal polymer film before the film is 79% or more of the average. This is because the transmission characteristics are good. Further, the average degree of orientation F in the thickness direction of the liquid crystal polymer film is, for example, preferably 0.31 or more, and more preferably 0.315 or more. This is because the transmission characteristics are particularly good.

Here, the "average degree of orientation F in the thickness direction" means, for example, a region of a predetermined MD length in a cross section perpendicular to the surface of the liquid crystal polymer film and parallel to the MD (vertical cross section) evenly in the thickness direction. It refers to the average value of a plurality of degrees of orientation F calculated from the infrared dichroic ratio D measured in each of a plurality of divided measurement regions (for example, five or more measurement regions). The plurality of measurement regions are not particularly limited, and examples thereof include five rectangular regions located at distances in the thickness direction from the surface shown in FIG. 3 at 5 μm, 15 μm, 25 μm, 35 μm, and 45 μm, respectively. Be done.

The dielectric loss tangent of the liquid crystal polymer film is not particularly limited, and it is preferable that the dielectric loss tangent is closer to the dielectric loss tangent of the liquid crystal polymer film before the metal layer is laminated. It is preferably less than 114%, more preferably less than 112% of the dielectric loss tangent of the liquid crystal polymer film before the metal layer is laminated, and even more preferably less than 110%. This is because the transmission characteristics are good. Specifically, the dielectric loss tangent of the liquid crystal polymer film is preferably less than 0.0024, for example. This is because the transmission characteristics are particularly good.

Here, the "dielectric loss tangent" refers to a dielectric loss tangent in the vicinity of 28 GHz. For example, a relative permittivity / dielectric loss tangent measurement system (DPS03 manufactured by Keycom Co., Ltd.) is used with a measurement frequency of 28 GHz by the open resonator method. Refers to what is measured.

The thickness of the liquid crystal polymer film can be appropriately set according to the use of the metal laminated film and the like. For example, when used as a flexible printed substrate, the thickness is preferably 10 μm or more and 150 μm or less, and more preferably 10 μm or more and 120 μm or less. The thickness of the liquid crystal polymer film can be measured with a micrometer or the like, and refers to the average value of the thickness measured at 10 points randomly selected from the surface of the target liquid crystal polymer film. Further, for the liquid crystal polymer film, the deviation from the average value of the measured values at 10 points is preferably 20% or less, more preferably 15% or less for all the measured values.

2. Metal layer The metal layer is not particularly limited as long as it has a metal foil, and as in the metal layer 10 in the metal laminated film 1A shown in FIG. 1, in addition to the metal foil, between the liquid crystal polymer film and the metal foil. It may have an intermediate layer containing a metal in the metal, or it may be a metal foil, but in addition to the metal foil, an intermediate layer containing a metal is further provided between the liquid crystal polymer film and the metal foil. preferable. Hereinafter, the metal foil of the metal layer and the intermediate layer when the metal layer has the intermediate layer and the metal foil will be described.

(1) Metal foil The metal foil varies depending on the use of the metal laminated film and is not particularly limited. For example, a single layer foil such as a copper foil, a nickel foil, an aluminum foil, and an iron foil, a laminated foil (clad material) thereof, and the like. Examples include alloy foils and rolled thin plates. As the metal foil, copper foil, copper alloy foil, or the like is preferable. This is because, for example, a flexible substrate for forming fine wiring can be obtained by rolling and joining these with a liquid crystal polymer film. Further, when producing a flexible substrate for forming finer wiring, it is preferable to use a carrier-attached copper foil composed of an ultrathin copper foil, a release layer, and a carrier layer as the metal foil. When a copper foil with a carrier is used, the copper foil with a carrier is laminated in the order of the ultrathin copper foil, the release layer, and the carrier layer from the liquid crystal polymer film side or the intermediate layer side. The copper foil with a carrier layer is not particularly limited, and examples thereof include MT18FL manufactured by Mitsui Mining & Smelting Co., Ltd. and JXUT-III manufactured by JX Nippon Mining & Metals Co., Ltd.

The thickness of the metal foil varies depending on the use of the metal laminated film and is not particularly limited. For example, in the case of a flexible printed wiring board application, it is preferably 3 μm or more and 100 μm or less, and more preferably 10 μm or more and 35 μm or less. When a copper foil with a carrier layer is used as the metal foil, the thickness of the ultrathin copper foil is not particularly limited, but is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less. The thickness of the release layer is not particularly limited, but is preferably 1 nm or more and 1 μm or less, and the thickness of the carrier layer is not particularly limited, but is preferably 10 μm or more and 100 μm or less.

Although not shown in FIG. 1, the metal layer is at least one of a roughened particle layer, a rust preventive layer, a treated layer with a silane coupling agent, and the like on the surface of the metal foil on the liquid crystal polymer film side. A layer (hereinafter, may be referred to as a “treatment layer”) may be further provided. As the treatment layer, any one type of layer may be laminated, or a plurality of types of layers may be laminated. The roughened particle layer can include, but is not limited to, any kind of metal selected from the group consisting of Cu, Co and Ni, or an alloy thereof. Specific examples thereof include a cobalt-cobalt-nickel alloy plating layer and a copper-cobalt-nickel alloy plating layer. Further, the rust preventive layer may contain, for example, any kind of metal selected from the group consisting of Cr, Ni and Zn or an alloy thereof, but is not limited thereto. Specific examples thereof include a coating treatment of chromium oxide, a coating treatment of a mixture of chromium oxide and zinc / zinc oxide, and a Ni plating layer. Further, examples of the silane coupling agent include, but are not limited to, olefin-based silanes, epoxy-based silanes, acrylic-based silanes, amino-based silanes, and mercapto-based silanes. The silane coupling agent can be applied by appropriately using a method such as spraying, coating with a coater, or dipping.

(2) Intermediate layer The intermediate layer is not particularly limited as long as it is a layer containing a metal, and may be a layer containing one metal layer or a laminated layer containing two or more layers of metal. Examples of the intermediate layer include a layer provided on a liquid crystal polymer film by sputter film formation, thin film deposition, or electroless plating.

The intermediate layer is not particularly limited as long as it contains a metal, but is composed of a group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver, gold, aluminum, palladium, and zirconium. Those containing any one of the selected metals or alloys containing the metals are preferred. Further, the intermediate layer may be one in which a plurality of layers containing a metal are laminated. In particular, when the metal foil is a copper foil or a copper alloy foil, it is preferable that the intermediate layer also contains a copper alloy such as copper or a copper nickel alloy, and among them, a metal having the same composition as the metal foil. Is preferable. This is because etching becomes easy.

When the intermediate layer is, for example, a Cu—Ni alloy, the ratio of Ni to Cu is preferably 10 to 90% at%. However, it is not limited to this. By providing the intermediate layer, it is possible not only to protect the surface of the metal foil or the liquid crystal polymer film and improve the adhesion between the metal foil and the liquid crystal polymer film, but also to impart a function peculiar to the intermediate layer. (For example, the function as an etching stopper layer during etching processing, etc.). The thickness of the intermediate layer may be any thickness as long as it can exert a function such as improving adhesion, and is not particularly limited. For example, 5 nm or more and 200 nm or less are preferable, and 10 nm or more and 100 nm or less are particularly preferable.

3. 3. The metal laminated film is not particularly limited, but as in the metal laminated film 1A shown in FIG. 1, the bonding strength between the metal layer and the liquid crystal polymer film is preferably 2.0 N / cm or more. This is because the reliability of the fine wiring of the printed wiring board can be improved.

In order to measure the value of the bonding strength, first, a test piece is prepared from a metal laminated film, and a notch having a width of 1 cm is made in the metal layer using a knife or the like. Then, after partially peeling the metal layer and the liquid crystal polymer film, the liquid crystal polymer film is fixed to the support, and the metal layer is placed at 50 mm / min in the 90 ° direction with respect to the liquid crystal polymer film. Pull at the speed of. The force required for peeling at that time is used as the joint strength (unit: N / cm). Further, if the metal layer is thin and fragile, it may be cut when measuring the joint strength. In that case, the surface of the metal layer may be electroplated (when the metal layer is copper, for example, copper plating) to increase the thickness of the metal layer to about 5 to 50 μm, and then the bonding strength may be measured. The method for measuring the value of the joint strength is the measuring method specified in JIS C6471.

In the present specification, the term "bonding strength between the metal layer and the liquid crystal polymer film" refers to the bonding strength when the metal layer and the liquid crystal polymer film are peeled off at the interface, and is also caused by the destruction of the inside of the metal layer. It also means the bonding strength at the time of peeling and the bonding strength at the time of peeling due to the destruction of the inside of the liquid crystal polymer film.

The metal laminated film can be used as a metal-clad laminate for producing a flexible printed substrate.

A printed wiring board on which fine wiring is formed can be obtained by using a metal laminated film. In the process of forming the wiring, an additional metal layer can be formed only on the wiring portion. Specifically, a printed wiring board can be obtained by appropriately using conventionally known methods such as a modified semi-additive method (MSAP method), a semi-additive method (SAP method), and a subtractive method. For example, when the modified semi-additive method (MSAP method) is used, the non-wiring portion on the metal layer in the metal laminated film is masked, and the unmasked portion is copper-plated to form an additional metal layer and masked. The printed wiring board can be manufactured by removing the metal layer hidden by the mask by etching. The "printed wiring board" in the present invention includes not only a laminated body in which wiring is formed, but also a board in which electronic components such as ICs are mounted after the wiring is formed.

In the metal laminated film 1A shown in FIG. 1, a case where a metal layer is laminated on one surface of a liquid crystal polymer film has been described, but the metal laminated film is not limited to this. That is, if necessary, metal layers may be provided on both surfaces of the liquid crystal polymer film. By using a metal laminated film having metal layers provided on both surfaces of the liquid crystal polymer film, it is possible to obtain a flexible printed substrate in which wiring is formed on both surfaces of the liquid crystal polymer film.

B. Method for Producing Metal Laminated Film Here, an embodiment related to the method for producing a metal laminated film of the present invention will be illustrated and described. 2A and 2B are schematic cross-sectional views showing a main part of an example of the method for producing a metal laminated film of the embodiment.

In the method for producing the metal laminated film of this example, first, a liquid crystal polymer film and a copper foil (metal foil) are prepared. The degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film is 0.4.

Next, as shown in FIG. 2A (a), one surface 20a of the liquid crystal polymer film 20 is activated by sputtering etching at room temperature using an activation treatment device (not shown). Subsequently, as shown in FIG. 2A (b), an intermediate layer 14 containing copper is sputtered and formed on the surface 20a of the activated liquid crystal polymer film 20 at room temperature using a sputtering apparatus (not shown). ..

Next, as shown in FIG. 2A (c), the surface 14a of the intermediate layer 14 is activated by sputtering etching at room temperature using an activation bonding device (not shown), and the surface 12a of the copper foil 12 is sputtered. It is activated by etching, and the activated surfaces of the intermediate layer 14 and the copper foil 12 are rolled and joined to each other at a reduction rate of 0 to 30%.

Next, as shown in FIG. 2B (d), the metal layer 10 having the intermediate layer 14 and the copper foil 12 and the liquid crystal polymer film 20 which were rolled and joined were subjected to a heat treatment furnace (not shown) in a vacuum atmosphere. Alternatively _{, in an inert gas atmosphere such as N 2} , Ar, NH gas (for example, N ₂ + 5% H ₂ mixed gas), the temperature of the liquid crystal polymer film 20 is -100 ° C. or higher and the melting point of the liquid crystal polymer film 20 is -10 ° C. or lower. Heat-treat with. This improves the adhesion between the metal layer 10 and the liquid crystal polymer film 20. As described above, as shown in FIG. 2B (e), the metal laminated film 1A is manufactured.

In the method for producing the metal laminated film of this example, the surface 20a of the liquid crystal polymer film 20 is activated by sputtering etching, the intermediate layer 14 is formed by sputtering, and the surfaces of the intermediate layer 14 and the copper foil 12 are subjected to sputtering etching. The activating treatment and the treatment of rolling and joining the activated surfaces of the intermediate layer 14 and the copper foil 12 are performed at room temperature. Then, heat treatment is performed at a temperature of the melting point of the liquid crystal polymer film 20 of −100 ° C. or higher and the melting point of the liquid crystal polymer film 20 of −10 ° C. or lower to improve the adhesion between the metal layer 10 and the liquid crystal polymer film 20. Therefore, unlike the case where the metal laminated film is produced by using the thermal laminating method, the liquid crystal polymer film 20 is not heated at a temperature near the melting point or a temperature exceeding the melting point, so that the metal layer 10 and the liquid crystal polymer film are not heated. In addition to improving the adhesion of the liquid crystal polymer film 20, it is possible to suppress the disorder of the orientation of the liquid crystal polymer film 20 and the deterioration of its dielectric properties, and it is possible to suppress the deterioration of the surface morphology of the liquid crystal polymer film 20.

Therefore, according to the method for producing a metal laminated film of the embodiment, as in the manufacturing method of the above example, a metal laminated film in which the adhesion between the metal layer and the liquid crystal polymer film is improved and the deterioration of the dielectric property is suppressed is suppressed. Can be manufactured. Therefore, it is possible to manufacture a metal laminated film that can achieve both the transmission characteristics of the printed wiring board and the reliability of the fine wiring.

Subsequently, each condition of the method for producing the metal laminated film of the embodiment will be described in detail.

1. 1. Preparation Step The liquid crystal polymer film prepared in the preparation step is not particularly limited, but a film having an orientation degree F at the center in the thickness direction of 0.4 or more is preferable, and Vecstar CTQ manufactured by Kuraray Co., Ltd. is particularly preferable. This is because the dielectric loss tangent is low and the dielectric properties are excellent.

Since the metal foil prepared in the preparatory step is the same as the metal foil described in the item of "A. Metal laminated film 2. Metal layer (1) Metal foil", the description here is omitted.

2. Intermediate layer laminating step The method of laminating an intermediate layer containing a metal on at least one surface of a liquid crystal polymer film in the intermediate layer laminating step is not particularly limited, but for example, at least one surface of the liquid crystal polymer film is activated by sputter etching. After the formation, a method of forming an intermediate layer containing a metal on the activated surface by etching is preferable. The conditions for performing sputtering film formation by this method can be appropriately set according to the metal type constituting the intermediate layer and the thickness of the intermediate layer. The metal types and thicknesses of the intermediate layers that make up the intermediate layer are the same as those explained in the section "A. Metal laminated film 2. Metal layer (2) Intermediate layer", so the explanation here is omitted. do.

3. 3. Activation step In the spatter etching treatment in the activation step, for example, a metal foil to be bonded or a liquid crystal polymer film provided with an intermediate layer is prepared as a long coil having a width of 100 mm to 600 mm, and the bonding surface of the metal foil or the intermediate layer is prepared. Is one electrode grounded on the ground, and an AC of 1 MHz to 50 MHz is applied between the electrode and the other electrode supported by insulation to generate a glow discharge, and the area of the electrode exposed in the plasma generated by the glow discharge. Can be performed as 1/3 or less of the area of the other electrodes. During the sputter etching process, the grounded electrode is in the form of a cooling roll to prevent the temperature of the conveyed material from rising.

In the sputter etching treatment in the activation step, the adsorbed substances on the surface are completely removed by sputtering the bonded surface of the metal foil or the liquid crystal polymer film provided with the intermediate layer with an inert gas under vacuum. Moreover, a part or all of the oxide layer on the surface is removed. It is preferable to completely remove the copper oxide layer. As the inert gas, argon, neon, xenon, krypton and the like, and a mixed gas containing at least one of these can be applied. Although it depends on the type of metal, adsorbents on the surface of the metal foil and the intermediate layer can be completely removed with an etching amount of about 1 nm, and in particular, the copper oxide layer is usually 5 nm to 12 nm (SiO ₂ equivalent). It can be removed by degree.

The processing conditions for sputter etching can be appropriately set according to the type of the metal foil and the intermediate layer and the like. For example, it can be performed under vacuum at a plasma output of 100 W to 10 kW and a line speed of 0.5 m / min to 30 m / min. The degree of vacuum at this time is preferably high in order to prevent re-adsorbed substances on the surface, but may be, for example, 1 × 10 ^-5 Pa to 10 Pa.

When a roughened particle layer or a rust preventive layer is provided on the surface of the metal foil, the surface of the roughened particle layer or the rust preventive layer is activated by sputter etching. At that time, the roughened particle layer and the rust preventive layer may be completely removed by sputter etching, or may remain without being removed.

Further, the surface of the metal foil or the surface of the intermediate layer before being activated by sputter etching is subjected to Ni plating, chromate treatment, silane coupling agent treatment, etc., if necessary, in order to prevent oxidation and improve adhesion. It may have been done. Further, the surface of the metal foil can be roughened as necessary in order to improve the adhesion with the intermediate layer.

4. Rolling and joining step The pressure welding between the activated surfaces of the metal foil and the intermediate layer that have undergone sputtering etching can be performed by roll pressure welding. The rolling wire load for roll pressure welding is not particularly limited, and can be set, for example, in the range of 0.1 tf / cm to 10 tf / cm. However, if the thickness of the liquid crystal polymer film provided with the metal foil or the intermediate layer before joining is large, it may be necessary to increase the rolling wire load in order to secure the pressure at the time of joining. It is not limited to the range. On the other hand, if the rolling wire load is too high, not only the surface layer of the metal foil or the intermediate layer but also the bonding interface is easily deformed, so that the thickness accuracy of each layer in the metal laminated film may decrease. Further, if the rolling wire load is high, the machining strain applied at the time of joining may increase.

The rolling reduction is 0 to 30%. It is preferably 0 to 15%. Since the reduction rate can be lowered by the above-mentioned method by surface activation bonding, it is possible to form a metal layer having excellent thickness accuracy without causing wrinkles or cracks. Further, since the waviness at the interface between the metal foil and the intermediate layer and the liquid crystal polymer film can be reduced, the thickness accuracy is excellent when pattern etching is performed on the metal foil and the metal layer having the intermediate layer to form wiring. Therefore, precise wiring can be obtained.

Bonding by roll pressure welding is performed in a non-oxidizing atmosphere, for example, in a vacuum atmosphere or an inert gas atmosphere such as Ar, in order to prevent the bonding strength between the two from being lowered due to readsorption of oxygen on the surface of the metal foil or the intermediate layer. It is preferable to do it inside.

5. Heat treatment step The heat treatment temperature is preferably −100 ° C. or higher for the liquid crystal polymer film or −10 ° C. or lower for the liquid crystal polymer film, and more preferably −70 ° C. or higher for the liquid crystal polymer film or −20 ° C. or lower for the liquid crystal polymer film. By setting the heat treatment temperature to the lower limit of these ranges or more, the bonding strength between the metal layer and the liquid crystal polymer film can be improved to a desired strength, and the shape of the curved metal laminated film during rolling bonding can be flattened. can. By setting the heat treatment temperature to the upper limit of these ranges or less, it is possible to prevent the orientation of the liquid crystal polymer film from being disturbed, and it is possible to prevent the metal laminated film from softening and changing its thickness and width. Since the melting point of the liquid crystal polymer film changes depending on the material, the heat treatment temperature can be appropriately set according to the material. For example, in the case of Vecstar CTQ manufactured by Kuraray Co., Ltd. (melting point: 310 ° C.), the heat treatment temperature. Is a temperature of 210 ° C. or higher and 300 ° C. or lower, and a temperature of 240 ° C. or higher and 290 ° C. or lower is preferable.

Atmosphere heat treatment is not particularly limited, a vacuum atmosphere, or N _2, Ar, is preferably an inert gas atmosphere such as NH 3 gas, among them a vacuum atmosphere and the like are preferable. This is because it is possible to prevent the metal layer from being oxidized by the heat treatment and the bonding strength between the metal layer and the liquid crystal polymer film from being lowered.

The time for applying the heat treatment is not particularly limited as long as the bonding strength between the metal layer and the liquid crystal polymer film can be made to a desired strength and the orientation of the liquid crystal polymer film can be avoided from being disturbed. Is preferable, and more preferably 200 seconds or more and 15,000 seconds or less. This is because sufficient adhesion between the metal layer and the liquid crystal polymer film can be ensured by setting the lower limit of these ranges or more, and high production efficiency of the metal laminated film by setting it below the upper limit of these ranges. This is because low cost can be realized.

Method of applying a heat treatment, for example, a batch type heat treatment furnace, a desired atmosphere (e.g., a vacuum atmosphere and N _2, Ar, inert gas atmosphere such as NH 3 gas), the desired metal layer and the liquid crystal polymer film Examples thereof include a method of maintaining the heat treatment temperature for a desired time. Further, depending on the heat treatment temperature and atmosphere, the heat treatment may be performed by a roll-to-roll method using a continuous heat treatment furnace. In that case, at least the heating section and the cooling section of a continuous heat treatment furnace, a desired atmosphere (e.g., vacuum atmosphere and N _2, Ar, inert gas atmosphere such as NH 3 gas), in terms of maintaining the desired temperature, Examples thereof include a method of maintaining the metal layer and the liquid crystal polymer film at a desired heat treatment temperature for a desired time by passing the metal layer and the liquid crystal polymer film through a heating part and a cooling part at a desired speed.

6. Method for Manufacturing Metal Laminated Film In the method for manufacturing a metal laminated film of the embodiment, the degree of orientation F at the center in the thickness direction of the liquid crystal polymer film after heat treatment is the thickness direction of the liquid crystal polymer film before the metal layers are laminated. It is preferably 77% or more of the degree of orientation F of the central portion. Specifically, the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film after the heat treatment is preferably 0.31 or more. Further, the dielectric loss tangent of the liquid crystal polymer film after the heat treatment is preferably less than 114% of the dielectric loss tangent of the liquid crystal polymer film before the metal layer is laminated, and above all, the liquid crystal polymer film before the metal layer is laminated. It is preferably less than 112% of the dielectric loss tangent, and more preferably less than 110%.

Since joining and / or heat treatment under high pressure during the production of the metal laminated film may significantly change the structure of each layer of the metal laminated film before and after joining and / or before and after the heat treatment, and may impair the characteristics of the metal laminated film. , It is preferable to select bonding / heat treatment conditions that can avoid such structural changes.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example 1)
First, a liquid crystal polymer film having a thickness of 50 μm (Vecstar CTQ-50 manufactured by Kuraray Co., Ltd.) was prepared, and two rolled copper foils having a thickness of 16 μm were prepared as metal foils. Next, both surfaces of the liquid crystal polymer film were activated one side at a time by sputtering etching, and then an intermediate layer (copper layer) (thickness 40 nm) containing copper was sputtered and formed on both of the activated surfaces one side at a time. .. Next, the surface of one intermediate layer and the surface of the rolled copper foil on one side were activated by sputter etching so that the activated surface of the rolled copper foil was in contact with the activated surface of the intermediate layer, and then 1 The intermediate layer and the activated surfaces of the rolled copper foil were rolled and joined with a linear load of .5 tf / cm. Further, the surface of the intermediate layer on the side where the rolled copper foil is not laminated is activated by sputter etching, the surface of the other rolled copper foil is activated by sputter etching, and rolled copper is applied to the activated surface of the intermediate layer. After the activated surfaces of the foil were brought into contact with each other, the intermediate layer and the activated surfaces of the rolled copper foil were rolled and joined with a linear load of 1.5 tf / cm. The reduction rate was 2.4%. Next, the intermediate layer, the metal layer having the rolled copper foil, and the liquid crystal polymer film were heat-treated in a vacuum atmosphere at 250 ° C. for 10800 seconds. As a result, a metal laminated film (layer structure: rolled copper foil / intermediate layer (copper layer) / liquid crystal polymer film / intermediate layer (copper layer) / rolled copper foil) was produced.

(Example 2)
First, a liquid crystal polymer film having a thickness of 25 μm (Vecstar CTQ-25 manufactured by Kuraray Co., Ltd.) was prepared, and a rolled copper foil having a thickness of 16 μm was prepared as a metal foil. Next, one surface of the liquid crystal polymer film was activated by sputtering etching, and then an intermediate layer (copper layer) (thickness 40 nm) containing copper was sputter-deposited on the activated surface. Next, the surface of the intermediate layer and the surface of the rolled copper foil were activated by sputter etching so that the activated surface of the rolled copper foil was in contact with the activated surface of the intermediate layer, and then 1.5 tf / cm. The intermediate layer and the activated surfaces of the rolled copper foil were rolled and joined with each other under the linear load of. The reduction rate was 2.4%. Next, the intermediate layer, the metal layer having the rolled copper foil, and the liquid crystal polymer film were heat-treated in a vacuum atmosphere at 280 ° C. for 10800 seconds. As a result, a metal laminated film (layer structure: rolled copper foil / intermediate layer (copper layer) / liquid crystal polymer film) was produced.

(Example 3)
Preparation: (rolled copper foil / intermediate layer (copper layer) / liquid crystal polymer film layer structure) except that heat-treated after rolling joined with an N ₂ atmosphere in the same manner as in Example 2, a metal laminate film bottom.

(Example 4)
A first intermediate layer (nickel layer) containing nickel (thickness 40 nm) and a second intermediate layer containing copper (copper layer) (thickness 40 nm) are sputtered on one surface of the liquid crystal polymer film in this order as intermediate layers. A metal laminated film (layer structure: rolled copper foil / second intermediate layer (copper layer) / first intermediate layer (nickel layer) / liquid crystal polymer film) was produced in the same manner as in Example 3 except for the filmed points. ..

(Example 5)
First, a liquid crystal polymer film having a thickness of 25 μm (Vexter CTQ-25 manufactured by Kuraray Co., Ltd.) was prepared, and as a metal foil, a carrier layer containing copper having a thickness of 18 μm was passed through a release layer (organic release layer) to a thickness of 1.5 μm. A copper foil with a carrier layer (MT18FL manufactured by Mitsui Metal Mining Co., Ltd.) was prepared in which an ultra-thin copper layer was provided and a roughened particle layer and a rust-preventive layer were further provided on the surface of the ultra-thin copper layer. Next, one surface of the liquid crystal polymer film was activated by sputtering etching, and then an intermediate layer (copper layer) (thickness 40 nm) containing copper was sputter-deposited on the activated surface. Next, the surface of the intermediate layer and the surface of the ultrathin copper layer are activated by sputter etching so that the activated surface of the intermediate layer is in contact with the activated surface of the ultrathin copper layer, and then 1.5 tf. The activated surfaces of the intermediate layer and the ultrathin copper layer were rolled and joined with a linear load of / cm. The reduction rate was 2.4%. Next, the metal layer having the intermediate layer and the copper foil with the carrier layer and the liquid crystal polymer film were heat-treated to be maintained at 250 ° C. for 10800 seconds in a vacuum atmosphere. As a result, a metal laminated film (layer structure: copper foil with carrier layer / intermediate layer (copper layer) / liquid crystal polymer film) was produced.

(Example 6)
As a metal foil, an ultrathin copper layer having a thickness of 5.0 μm is provided on a carrier layer containing copper having a thickness of 18 μm via a release layer (organic release layer), and only a rust preventive layer is provided on the surface of the ultrathin copper layer. A metal laminated film (layer structure: copper foil with carrier layer / An intermediate layer (copper layer) / liquid crystal polymer film) was prepared.

(Example 7)
First, a liquid crystal polymer film having a thickness of 25 μm (Vecstar CTQ-25 manufactured by Kuraray Co., Ltd.) was prepared, and as a metal foil, a carrier layer containing copper having a thickness of 18 μm was passed through a release layer (inorganic release layer) to a thickness of 2.0 μm. A copper foil with a carrier layer was prepared in which the ultra-thin copper layer was provided and only the rust preventive layer was provided on the surface of the ultra-thin copper layer. Next, one surface of the liquid crystal polymer film was activated by sputtering etching, and then an intermediate layer (copper layer) (thickness 40 nm) containing copper was sputter-deposited on the activated surface. Next, the surface of the intermediate layer and the surface of the ultrathin copper layer are activated by sputter etching so that the activated surface of the intermediate layer is in contact with the activated surface of the ultrathin copper layer, and then 1.5 tf. The activated surfaces of the intermediate layer and the ultrathin copper layer were rolled and joined with a linear load of / cm. The reduction rate was 2.4%. Then, the metal layer and the liquid crystal polymer film having an intermediate layer and a carrier layer with a copper foil to, was subjected to heat treatment to keep 10800 seconds at 280 ° C. at a N ₂ atmosphere. As a result, a metal laminated film (layer structure: copper foil with carrier layer / intermediate layer (copper layer) / liquid crystal polymer film) was produced.

(Example 8)
A first intermediate layer (nickel layer) containing nickel (thickness 40 nm) and a second intermediate layer containing copper (copper layer) (thickness 40 nm) are sputtered on one surface of the liquid crystal polymer film in this order as intermediate layers. A metal laminated film (layer structure: copper foil with carrier layer / second intermediate layer (copper layer) / first intermediate layer (nickel layer) / liquid crystal polymer film) is applied in the same manner as in Example 7 except for the filmed points. Made.

(Comparative Example 1)
By the thermal laminating method, a rolled copper foil having a thickness of 12 μm having a treated layer made of a roughened particle layer or the like on one side was applied to both surfaces of a liquid crystal polymer film having a thickness of 50 μm (Vexter CTQ-50 manufactured by Kuraray Co., Ltd.). A metal laminated film (layer structure: rolled copper foil / liquid crystal polymer film / rolled copper foil) was produced by heat-pressing the sheets one by one. In the metal laminated film, the liquid crystal polymer film is sandwiched between the two rolled copper foils so that the surfaces of the treated layers of the two rolled copper foils are in contact with both surfaces of the liquid crystal polymer film, and the liquid crystal polymer film is 310. The surfaces of the liquid crystal polymer film and the rolled copper foil are joined to each other by hot-press molding the liquid crystal polymer film and the rolled copper foil by heating to a temperature of ° C. or higher.

(Comparative Example 2)
By the thermal laminating method, an electrolytic copper foil having a thickness of 12 μm having a treated layer made of a roughened particle layer or the like on one side was applied to both surfaces of a liquid crystal polymer film having a thickness of 50 μm (Vexter CTQ-50 manufactured by Kuraray Co., Ltd.). A metal laminated film (layer structure: electrolytic copper foil / liquid crystal polymer film / electrolytic copper foil) was produced by thermocompression bonding one by one. In the metal laminated film, the liquid crystal polymer film is sandwiched between the two electrolytic copper foils so that the surfaces of the treated layers of the two electrolytic copper foils are in contact with both surfaces of the liquid crystal polymer film, and the liquid crystal polymer film is 310. The surfaces of the liquid crystal polymer film and the electrolytic copper foil are joined to each other by hot-press molding the liquid crystal polymer film and the electrolytic copper foil by heating to a temperature of ° C. or higher.

[Orientation degree F of liquid crystal polymer film]
The copper layer and the electrolytic copper foil were chemically removed by etching with a ferric chloride solution or the like from the metal laminated films of Example 1 and Comparative Example 2, respectively, and the size of the liquid crystal polymer film after removing them was about 4 μm in the width direction. The sections were cut out, and the degree of orientation F of each region in the thickness direction of each section was measured. Further, for comparison, a section having a dimension of about 4 μm in the width direction was cut out from the same untreated liquid crystal polymer film used for producing the metal laminated films of Example 1 and Comparative Example 2, and the thickness of the section was cut out. The degree of orientation F of each region in the direction was measured. FIG. 3 is a schematic view showing a measurement region of the degree of orientation F in a section of the liquid crystal polymer film.

In the measurement of the degree of orientation F, as shown in FIG. 3, in the cross section (vertical cross section) perpendicular to the surface of the section of the liquid crystal polymer film and parallel to the MD, the distances in the thickness direction from the surface are 5 μm, 15 μm, and 25 μm. Each rectangular region located at 35 μm and 45 μm was used as a measurement region with an aperture, and the infrared dichroic ratio D was measured by microinfrared spectroscopic analysis in each measurement region, and the degree of orientation F was calculated from the infrared dichroic ratio D. .. The measuring device, measuring method, and polarizer used, and the measuring conditions are as follows.

Measuring device: Agilent Technologies Co., Ltd. Cary670 / 620
Measurement method: Polarized microscopic FT-IR analysis / transmission method Aperture size: MD length 100 μm × thickness direction length 10 μm
Polarizer: Subbase KRS-5
Resolution: 4 cm ^-1
Accumulation number: 128 times

The infrared dipole ratio D was determined from the intensity of the peak of ^{1601 cm -1} , which is attributed to the C = C expansion and contraction vibration of the benzene ring and has a transition moment parallel to the molecular chain. Specifically, the intensity A‖ of the peak of the infrared transmission spectrum measured in the polarization direction parallel to the MD and the intensity A⊥ of the peak of the infrared transmission spectrum measured in the polarization direction perpendicular to the MD are set to 1601 cm ^-1 . the straight line connecting the points of the points and 1572.4Cm ^-1 in the spectrum of 1618.9Cm ^-1 and quantitated peaks peaks on measured as a baseline to determine the infrared dichroic ratio D by the formula (1). Further, the degree of orientation F with respect to MD was calculated by the formula (2).

^{The intensity A‖ and intensity A⊥ of the peak of 1601 cm -1} measured for each position of the measurement region for the untreated and the sections of the liquid crystal polymer films of Example 1 and Comparative Example 2, the infrared dichroic ratio D, and the degree of orientation F. And the average value of the degree of orientation F in the thickness direction for each section are shown in Table 1. Further, FIG. 4 is a graph showing the degree of orientation F for each position of the measurement region in the untreated and the sections of the liquid crystal polymer films of Examples and Comparative Examples 2.

As shown in Table 1 and FIG. 4, the sections of the liquid crystal polymer films of Example 1 and Comparative Example 2 had a lower degree of orientation F in the entire thickness direction as compared with the sections of the untreated liquid crystal polymer films. Then, when the sections of the liquid crystal polymer films of Example 1 and Comparative Example 2 are compared, the degree of orientation F of the sections of the liquid crystal polymer film of Example 1 is as a whole in the thickness direction as compared with the sections of the liquid crystal polymer film of Comparative Example 2. It got higher. Further, in the untreated and the section of the liquid crystal polymer film of Example 1, unlike the section of the liquid crystal polymer film of Comparative Example 2, the measurement region located on the central side in the thickness direction (distance in the thickness direction from the surface of the section: The degree of orientation of 15 μm, 25 μm, and 35 μm) tended to be higher than the degree of orientation of the measurement region (distance in the thickness direction from the surface of the section: 5 μm and 45 μm) located on the surface side in the thickness direction.

[Dielectric properties of liquid crystal polymer film]
The copper layer, rolled copper foil, and electrolytic copper foil were chemically removed by etching with a ferric chloride solution or the like from the metal laminated films of Example 1, Comparative Example 1, and Comparative Example 2, respectively, and Example 1 and Comparative Example Liquid crystal polymer films for measuring the dielectric properties of No. 1 and Comparative Example 2 were produced. Then, the same untreated liquid crystal polymer film used for producing the metal laminated film of Example 1, Comparative Example 1, and Comparative Example 2, and the dielectric of Example 1, Comparative Example 1, and Comparative Example 2 The thickness, relative permittivity and dielectric loss tangent of the liquid crystal polymer film for characteristic measurement were measured. The relative permittivity and the dielectric loss tangent were measured by the open resonator method at a measurement frequency of 28 GHz using a relative permittivity / dielectric loss tangent measurement system (DPS03 manufactured by Keycom Co., Ltd.). The results of these measurements are shown in Table 2.

As shown in Table 2, the increase in dielectric loss tangent of the liquid crystal polymer films of Comparative Example 1 and Comparative Example 2 with respect to the untreated liquid crystal polymer film exceeded 14%, whereas the amount of increase in the dielectric loss tangent with respect to the untreated liquid crystal polymer film was more than 14%. The amount of increase in the dielectric loss tangent of the liquid crystal polymer film No. 1 was less than 5%.

[Bonding strength between metal layer and liquid crystal polymer film]
For the metal laminated films of Examples 1 to 8 and Comparative Examples 1 and 2, the bonding strength between the metal layer and the liquid crystal polymer film was measured by the measuring method described in the item of "A. Metal laminated film 3. Metal laminated film". .. Regarding the metal laminated films of Examples 5 to 8, after removing the carrier layer and the peeling layer of the copper foil with the carrier layer to expose the ultrathin copper layer, "A. Metal laminated film 3. Metal laminated film. In order to prevent cutting of the thin and fragile ultra-thin copper layer, electrolytic copper plating is applied to the surface of the ultra-thin copper layer, and the thickness of the ultra-thin copper layer is similar to the method of applying electrolytic plating to the surface of the metal layer described in the item of "". Then, the bonding strength between the metal layer and the liquid crystal polymer film was measured. The results of these measurements are shown in Table 3.

As shown in Table 3, in each of the metal laminated films of Examples 1 to 8, the bonding strength between the metal layer and the liquid crystal polymer film was 2.0 N / cm or more. Further, in the metal laminated films of Examples 1 to 8, the higher the heat treatment temperature, the higher the bonding strength tended to be.

1A Metal laminated film 10 Metal layer 12 Copper foil (metal foil)
12a Copper foil surface 14 Intermediate layer 14a Surface of the intermediate layer opposite to the liquid crystal polymer film side 20 Liquid crystal polymer film 20a One surface of the liquid crystal polymer film

Claims (13)

A metal layer is laminated on at least one surface of the liquid crystal polymer film.
A metal laminated film characterized in that the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film is 0.31 or more. A metal layer is laminated on at least one surface of the liquid crystal polymer film.
The orientation degree F of the central portion in the thickness direction of the liquid crystal polymer film is 77% or more of the orientation degree F of the central portion in the thickness direction of the liquid crystal polymer film before the metal layers are laminated. Metal laminated film. The metal laminated film according to claim 1 or 2, wherein the average degree F of orientation F in the thickness direction of the liquid crystal polymer film is 0.31 or more. The metal lamination according to any one of claims 1 to 3, wherein the dielectric loss tangent of the liquid crystal polymer film is less than 114% of the dielectric loss tangent of the liquid crystal polymer film before the metal layer is laminated. the film. The metal laminated film according to any one of claims 1 to 4, wherein the bonding strength between the metal layer and the liquid crystal polymer film is 2.0 N / cm or more. The metal laminated film according to any one of claims 1 to 5, wherein the metal layer has a metal foil. The metal laminated film according to claim 6, wherein the metal layer further has an intermediate layer containing a metal between the liquid crystal polymer film and the metal foil. The intermediate layer comprises any one metal selected from the group consisting of copper, iron, nickel, zinc, chromium, cobalt, titanium, tin, platinum, silver, and gold, or an alloy containing the metal. The metal laminated film according to claim 7. The metal laminated film according to any one of claims 6 to 8, wherein the metal foil is a copper foil, a copper alloy foil, or a copper foil with a carrier. The method for producing a metal laminated film according to claim 7.
The process of preparing the liquid crystal polymer film and the metal foil,
A step of laminating an intermediate layer containing a metal on at least one surface of the liquid crystal polymer film, and
A step of activating the surface of the intermediate layer by sputter etching and
A step of activating the surface of the metal foil by sputter etching and
A step of rolling and joining the intermediate layer and the activated surfaces of the metal foil at a rolling reduction of 0 to 30%.
A step of heat-treating the rolled-bonded intermediate layer, the metal layer having the metal foil, and the liquid crystal polymer film at a temperature of the melting point of the liquid crystal polymer film of −100 ° C. or higher and the melting point of −10 ° C. or lower.
A method for producing a metal laminated film comprising. The method for producing a metal laminated film according to claim 10, wherein the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film after the heat treatment is 0.31 or more. The degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film after the heat treatment is 77% or more of the degree of orientation F of the central portion in the thickness direction of the liquid crystal polymer film before the metal layers are laminated. The method for producing a metal laminated film according to claim 10 or 11. The invention according to any one of claims 10 to 12, wherein the dielectric loss tangent of the liquid crystal polymer film after the heat treatment is less than 114% of the dielectric loss tangent of the liquid crystal polymer film before the metal layer is laminated. The method for producing a metal laminated film according to the above.

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