TW201605612A - Liquid crystal polymer film attached with metal foils and its manufacturing method, multi-layer printed wiring board and its manufacturing method - Google Patents

Abstract

The present invention relates to liquid crystal polymer film attached with metal foils, which comprises a liquid crystal polymer film; a first metal foil; and a second metal foil. The first metal foil is laminated on a first surface of the liquid crystal polymer film. The second metal foil is laminated on a second surface opposite to the first surface of the liquid crystal polymer film. The second metal foil comprises: a rough surface, and an electrolytic metal foil on a smooth surface opposite to the rough surface. The rough surface of the second metal foil and the second surface of the liquid crystal polymer film are laminated to each other, and a film release treatment is performed on the rough surface.

Description

Liquid crystal polymer film with metal foil, method for producing same, multilayer printed wiring board, and method of manufacturing same

The present disclosure relates to a liquid crystal polymer film with a metal foil, a method for producing the same, and a multilayer printed wiring board using the liquid crystal polymer film with the metal foil, and a method for producing the same.

In recent years, the improvement of the high frequency characteristics of the multilayer printed wiring board has been sought. Therefore, development of a multilayer printed wiring board using a liquid crystal polymer having excellent high-frequency characteristics was carried out.

For example, Patent Document 1 describes a method of producing a single-sided metal-clad laminate. The metal foil, the insulating film, and the separation film are laminated by thermocompression bonding, and then the separation film is peeled off to obtain a single-sided metal-clad laminate. Here, a thermoplastic liquid crystal polymer film is used as the insulating film.

Further, Patent Document 2 describes a method for producing a liquid crystal polymer film laminated substrate. The surface of the liquid crystal polymer film is roughened with an etching solution. Next, the liquid crystal polymer film is accumulated with the surface of the roughened liquid crystal polymer film facing the surface of the layered substrate. The layer substrates are laminated. Thereafter, the laminated substrate and the liquid crystal polymer film are integrated by heat and pressure treatment. Here, in the laminated substrate, a liquid crystal polymer film or a metal foil in which metal wiring is formed is used.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] International Publication No. WO2011/093427

[Patent Document 2] Japanese Patent Application Publication No. 2005-81649

The metal foil-attached liquid crystal polymer film of the present invention includes a liquid crystal polymer film, a first metal foil, and a second metal foil. The first metal foil is laminated on the first surface of the liquid crystal polymer film. The second metal foil is laminated on the second surface on the opposite side of the first surface of the liquid crystal polymer film. The second metal foil has an electrolytic metal foil having a rough surface and a smooth surface on the opposite side of the rough surface. The rough surface of the second metal foil and the second surface of the liquid crystal polymer film are laminated, and the mold release treatment is performed on the rough surface.

Further, the multilayer printed wiring board of the present invention includes a one-side metal foil liquid crystal polymer film in which the second metal foil is peeled off from the metal foil-attached liquid crystal polymer film, a bonding sheet, and a core material. The bonding sheet is a liquid crystal polymer film laminated on a single-sided metal foil liquid crystal polymer film. The core material has a conductor pattern and is laminated on the bonding sheet. The surface of the bonding sheet opposite to the surface on which the liquid crystal polymer film is laminated is laminated on the surface of the core material on which the conductor pattern is formed.

The method for manufacturing a liquid crystal polymer film with metal foil disclosed in the present disclosure is In the first metal layer of the first area layer of the liquid crystal polymer film, the anode electrode and the rotating drum as the cathode electrode are immersed in an electrolytic solution containing metal ions, and a current flows between the anode electrode and the cathode electrode, thereby making the second metal foil The metal foil is electrodeposited on the surface of the rotating drum, and the second metal foil is peeled off by the rotating drum, and the surface of the second metal foil that is in contact with the surface of the rotating drum is made into a shiny surface, and the second metal foil is used as the original. The surface that is not in contact with the surface of the rotating drum is a rough surface, and a release agent is applied to the rough surface of the second metal foil, and the second area layer on the opposite side of the first surface of the liquid crystal polymer film is used. 2 The rough surface of the metal foil is used to form a laminate, and the laminate is pressurized and heated.

In the method for producing a multilayer printed wiring board according to the present disclosure, the second metal foil is peeled off from the metal foil-attached liquid crystal polymer film, and a bonding sheet formed of a liquid crystal polymer is laminated on the surface after the second metal foil is peeled off. The multilayer substrate is formed by laminating the surface of the core material on which the conductor pattern is formed on the surface opposite to the surface on which the laminated liquid crystal polymer film is laminated, and the multilayer substrate is pressurized and heated.

1‧‧‧ Liquid crystal polymer film with metal foil

2‧‧‧Multilayer printed wiring board

4‧‧‧Liquid polymer film

4a, 7a, 31a, 32a‧‧‧

5‧‧‧ Bonding sheet

6‧‧‧Conductor pattern

6a‧‧‧ Inner layer pattern

6b‧‧‧ outer pattern

7‧‧‧ core material

8‧‧‧Insulation

9a‧‧‧through holes

9b‧‧‧through hole

10‧‧‧One-sided metal foil liquid crystal polymer film

20‧‧‧Multilayer substrate

31‧‧‧1st metal foil

31b, 32b‧‧‧ smooth surface

32‧‧‧2nd metal foil

32c‧‧‧ release layer

33‧‧‧metal foil

40‧‧‧1st

41‧‧‧2nd

45, 57‧‧‧ interface

Fig. 1A is a schematic cross-sectional view showing a method of producing a metal foil-attached liquid crystal polymer film obtained by the present embodiment.

Fig. 1B is a schematic cross-sectional view showing a method of producing a metal foil-attached liquid crystal polymer film obtained by the present embodiment.

1C is a schematic cross-sectional view showing a state in which the second metal foil is peeled off from the liquid crystal polymer film with a metal foil obtained in the present embodiment.

Fig. 2A is a schematic cross-sectional view showing a method of manufacturing a multilayer printed wiring board obtained in the present embodiment.

Fig. 2B is a schematic cross-sectional view showing a method of manufacturing the multilayer printed wiring board obtained in the present embodiment.

Fig. 2C is a schematic cross-sectional view showing a method of manufacturing the multilayer printed wiring board obtained in the present embodiment.

Fig. 3 is a view showing a photograph of the surface of the second metal foil after peeling off the liquid crystal polymer film with a metal foil obtained in the present embodiment.

Fig. 4 is a view showing a photograph of the surface of the second metal foil after peeling off the liquid crystal polymer film with a metal foil obtained in the present embodiment.

Fig. 5 is a view showing a photograph of the surface of the second metal foil after peeling off the liquid crystal polymer film with a metal foil obtained by the comparative example.

When the single-sided metal-clad laminate formed by the method of Patent Document 1 is bonded to the bonded sheet, the adhesion may be weak.

Further, in Patent Document 2, it is necessary to have a process of etching the surface of the liquid crystal polymer film. Further, when the laminated liquid crystal substrate is superposed on one surface of the liquid crystal polymer film to be integrated, usually in a liquid crystal polymer The other side of the film is laminated with a release film or the like. When the film is heated and pressurized in this state, the liquid crystal polymer film is softened, and the other surface is transferred to the surface state of the release film or the like to be smoothed.

Embodiments of the present disclosure will be described below.

1A and 1B are schematic cross-sectional views showing a method of manufacturing a liquid crystal polymer film 1 with a metal foil obtained in the present embodiment.

The liquid crystal polymer film 1 with a metal foil includes a liquid crystal polymer film 4, a first metal foil 31, and a second metal foil 32. The first metal foil 31 is laminated on the first surface 40 of the liquid crystal polymer film 4. The second metal foil 32 is laminated on the second surface 41 on the opposite side of the first surface 40 of the liquid crystal polymer film 4 . The second metal foil 32 has an electrolytic metal foil having a rough surface 32a and a smooth surface 32b on the opposite side of the rough surface 32a. The rough surface 32a of the second metal foil 32 and the second surface 41 of the liquid crystal polymer film 4 are laminated, and the rough surface 32a is subjected to a mold release treatment.

The manufacturing method of the liquid crystal polymer film 1 with a metal foil has the process of superposing the 1st metal foil 31, the liquid-crystal polymer film 4, and the 2nd metal foil 32 sequentially, and heating and press. 1C is a schematic cross-sectional view showing a state in which the second metal foil 32 is peeled off from the liquid crystal polymer film 1 with a metal foil obtained in the present embodiment. The state of FIG. 1C is referred to as a one-sided metal foil liquid crystal polymer film 10.

First, the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 used in the production of the liquid crystal polymer film 1 with a metal foil will be described.

For the first metal foil 31, for example, a copper foil or a stainless steel foil is used. Nickel foil, nickel chrome alloy foil, etc. At least one surface of the first metal foil 31 is preferably a rough surface 31a. In the present embodiment, a case where one surface of the first metal foil 31 is a rough surface 31a and the other surface is a smooth surface 31b will be described. However, both surfaces of the first metal foil 31 may be rough surfaces 31a.

Here, the rough surface 31a means a surface on which fine irregularities are formed. Specifically, the ten-point average roughness Rz of the rough surface 31a is preferably 0.5 μm or more and 5.0 μm or less. The smooth surface 31b is a smooth surface. The ten-point average roughness Rz of the smooth surface 31b is not particularly limited, and may be, for example, 0.5 μm or more and 2.5 μm or less.

The first metal foil 31 can be produced by a calendering method, an electrolysis method, or the like. In the rolling method, for example, by performing surface treatment such as roughening treatment, the rough surface 31a having the ten-point average roughness Rz as described above is formed in the first metal foil 31. In the electrolysis method, for example, an appropriate surface treatment such as adjustment of electrolysis conditions or roughening treatment is performed, whereby the rough surface 31a having the ten-point average roughness Rz as described above is formed in the first metal foil 31. The thickness of the first metal foil 31 is, for example, 5.0 μm or more and 70.0 μm or less.

The liquid crystal polymer film 4 is formed into a film-like liquid crystal polymer. For the liquid crystal polymer, for example, a polyarylate-based liquid crystal polymer, a wholly aromatic polyester, or a semi-rigid aromatic polyester, or a polyester decylamine or the like is used. Alternatively, in the case of a liquid crystal polymer, (1) an aromatic or aliphatic dihydroxy compound, or (2) an aromatic or aliphatic dicarboxylic acid, or (3) an aromatic hydroxycarboxylic acid, or (4) A copolymer of a raw material such as an aromatic diamine, an aromatic hydroxylamine or an aromatic aminocarboxylic acid. The surface of the liquid crystal polymer film 4 may be a rough surface or a smooth surface. Liquid crystal polymer film 4 The thickness is, for example, 12 μm or more and 200 μm or less. The liquid crystal polymer film 4 is laminated on the rough surface 31a of the first metal foil 31.

The second metal foil 32 is laminated on the liquid crystal polymer film 4. The second metal foil 32 is an electrolytic metal foil, and for example, a copper foil, a stainless steel foil, a nickel foil, a nichrome foil, or the like is used. The material of the second metal foil 32 is preferably the same as the material of the first metal foil 31. By making the material of the second metal foil 32 and the first metal foil 31 the same, the warpage of the metal foil-attached liquid crystal polymer film 1 shown in FIG. 1B can be suppressed.

A method of producing a metal foil (electrolytic metal foil) used as the second metal foil 32 will be described below. A rotating drum and an anode electrode functioning as a cathode are immersed in an electrolytic solution containing metal ions. The rotating drum is formed of titanium or the like. While rotating the rotary drum, an electric current flows between the anode and the cathode, whereby the metal foil is electrodeposited on the rotary drum, and the metal foil is peeled off from the surface of the rotary drum. By this method, a metal foil is continuously produced. For example, if the metal foil is a copper foil, a copper sulfate solution is used as the electrolytic solution.

The rough surface 32a of the second metal foil 32 is a surface of the electrolytic metal foil that is not in contact with the rotating drum. Further, the smooth surface 32b of the second metal foil 32 is a surface on which the original of the electrolytic metal foil is in contact with the rotary drum. Here, the rough surface 32a is also referred to as a rough surface (Mat surface) and an M surface. Further, the smooth surface 32b is also referred to as a glossy surface (Shiny surface) and an S surface.

The surface of the smooth surface 32b is formed into a shape in which the surface state of the rotary drum is transferred, and thus is generally smooth. The ten-point average roughness Rz of the smooth surface 32b is not particularly limited, and is, for example, 0.5 μm or more and 2.5 μm or less. can.

On the other hand, the rough surface 32a is a surface on which a metal is deposited by electrodeposition. The electrodeposition speed at the time of electrodeposition is not uniform throughout the entire surface of the rotary drum, and may vary depending on the slight surface state of the rotary drum or the flow pattern of the electrolyte. Therefore, unevenness occurs in the thickness of the metal foil. When the projection is formed due to the uneven thickness of the metal foil, the electrolytic density in the electrolytic solution near the projection becomes high, and the projection is more easily electrodeposited than the surroundings. As a result, irregularities are formed on the entire rough surface 32a, and a roughened surface state can be obtained. This roughness can be controlled by adjusting the electrolyte concentration or the electrolytic conditions such as additives. The ten-point average roughness Rz of the rough surface 32a is preferably 1.0 μm or more and 5.0 μm or less.

In the electrolytic copper foil used for the printed wiring board, in order to ensure adhesion to the resin constituting the insulating layer, a roughening treatment for forming fine particles such as copper particles on the rough surface may be performed, and the microparticle adhesion treatment may be performed. The quasi-effect is improved due to the adhesion treatment of the particles. This microparticle attachment treatment is also referred to as a roughening treatment with an ridge.

However, in the present embodiment, it is preferable that the rough surface 32a of the second metal foil 32 is not subjected to the fine particle adhesion treatment. In the present embodiment, the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 are stacked in this order, and a liquid crystal polymer film 1 (layered body) with a metal foil is produced by heating and pressurization. Further, by peeling off the second metal foil 32 from the laminated body, the surface of the liquid crystal polymer film 4 from which the second metal foil 32 has been peeled off becomes a rough surface. Further, the bonding sheet 5 is laminated on the surface of the liquid crystal polymer film 4 from which the second metal foil 32 has been peeled off, and the core sheet is laminated on the bonding sheet 5. 7 to fabricate the multilayer substrate 20. Next, the multilayer wiring board 20 is heated and pressurized to multiply the printed wiring board 2 (see FIGS. 2A to 2C). When the fine particle adhesion treatment is performed on the rough surface 32a of the second metal foil 32, the adhesion strength between the liquid crystal polymer film 4 and the second metal foil 32 is excessively strong. As a result, it may be difficult to peel off the second metal foil 32 from the liquid crystal polymer film 4. In addition, when the second metal foil 32 is peeled off, fine particles such as copper particles may fall off from the second metal foil 32 and remain in the liquid crystal polymer film 4 . As a result, fine particles such as copper particles are embedded in the multilayer printed wiring board 2, and this may cause a short circuit or migration between circuits.

The mold release treatment is performed on the rough surface 32a of the second metal foil 32. In other words, the release layer 32c is formed by applying a release agent to the rough surface 32a. For the release agent, for example, a fluorine-based release agent, a oxime-based release agent, or the like is used. The ten-point average roughness Rz of the rough surface 32a subjected to the mold release treatment is preferably 1.0 μm or more and 5.0 μm or less. The thickness of the second metal foil 32 subjected to the mold release treatment is, for example, 12 μm or more and 35 μm or less. However, the ten-point average roughness Rz of the rough surface 32a of the second metal foil 32 and the thickness of the second metal foil 32 hardly change before and after the mold release treatment.

Next, a method of manufacturing the liquid crystal polymer film 1 with a metal foil will be specifically described.

As shown in FIG. 1A and FIG. 1B, the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 are sequentially stacked. In other words, the liquid crystal polymer film 4 is interposed between the first metal foil 31 and the second metal foil 32. At this time, the surface of the liquid crystal polymer film 4 in which the first metal foil 31 is superposed is preferably thick. Face 31a. Further, the surface of the second metal foil 32 which is superposed on the liquid crystal polymer film 4 is a rough surface 32a, and the rough surface 32a is subjected to a mold release treatment to form a release layer 32c. In the state of being superposed as described above, the laminate is formed by heating and pressurizing for a predetermined period of time. The forming can be continuous or monolithic. In the continuous type, the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 are each formed into an elongated shape, and the one side is formed while being transported in the longitudinal direction. In the one-piece type, the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 are uniformly cut into a predetermined size to form one set, and one set is formed into one set. In the molding conditions, for example, a pressure of 0.5 MPa or more and 6 MPa or less is applied at a temperature of 250 ° C or more and 350 ° C or less for 1 minute or more and 120 minutes or less. The liquid crystal polymer film 4 is softened by heating and pressurization, and the softened liquid crystal polymer film 4 is followed by the first metal foil 31 and the second metal foil 32. Thereafter, when the heating and the pressure are stopped and cooling is performed as necessary, the originally softened liquid crystal polymer film 4 is solidified, and integrated together with the first metal foil 31 and the second metal foil 32, and the film shown in FIG. 1B is obtained. A liquid crystal polymer film 1 (layered body) with a metal foil.

In the metal foil-attached liquid crystal polymer film 1 obtained as described above, the surface of the liquid crystal polymer film 4 overlapped by the first metal foil 31 is a rough surface 31a, so that the first effect is the first effect. The adhesion between the metal foil 31 and the liquid crystal polymer film 4 is enhanced. On the other hand, the shape of the fine unevenness of the rough surface 32a of the second metal foil 32 is transferred to the liquid crystal polymer film 4. As shown in FIG. 1C, when the second metal foil 32 is peeled off from the metal foil-attached liquid crystal polymer film 1, the rough surface of the liquid crystal polymer film 4 4a will be exposed. The rough surface 4a is transferred to the rough surface 32a of the second metal foil 32, and fine unevenness is formed. As described above, the surface of the liquid crystal polymer film 4 can be roughened even if etching is not performed.

When the ten-point average roughness Rz of the rough surface 32a of the second metal foil 32 to which the mold release treatment is applied is 1.0 μm or more, the liquid crystal polymer film 4 can be formed and the bonding sheet 5 can be further improved (see FIGS. 2A to 2C). The adhesion of the rough surface 4a. The mold release layer 32c is formed by performing a mold release process on the rough surface 32a of the 2nd metal foil 32. Therefore, the second metal foil 32 can be easily peeled off from the metal foil-attached liquid crystal polymer film 1 by the second metal foil 32 having the rough surface 32a having a ten-point average roughness Rz of 5.0 μm or less. In other words, the ten-point average roughness Rz of the rough surface 32a of the second metal foil 32 is preferably 1.0 μm or more and 5.0 μm or less. Specifically, the peeling strength of the liquid crystal polymer film 4 and the second metal foil 32 is preferably 0.4 N/mm or less. Thereby, the second metal foil 32 can be more easily peeled off from the metal foil-attached liquid crystal polymer film 1. The substantial lower limit of the peel strength is 0.01 N/mm. In other words, the peeling strength of the liquid crystal polymer film 4 and the second metal foil 32 is preferably 0.01 N/mm or more and 0.4 N/mm or less.

Next, a method of manufacturing the multilayer printed wiring board 2 using the metal foil-attached liquid crystal polymer film 1 produced by the above method will be described with reference to Figs. 2A to 2C.

First, the bonding sheet 5 and the core material 7 used in the production of the multilayer printed wiring board 2 will be described.

The bonding sheet 5 is formed into a sheet-like liquid crystal polymer. As will be described later, the liquid crystal polymer of the bonding sheet 5 is formed by using a melting point ratio to form a liquid crystal polymer. The liquid crystal polymer of the film 4 is preferably a lower liquid crystal polymer. However, the liquid crystal polymer of the bonding sheet 5 may be the same as the liquid crystal polymer of the liquid crystal polymer film 4. The surface of the bonding sheet 5 may be a rough surface or a smooth surface. The thickness of the bonding sheet 5 is, for example, 25 μm or more and 200 μm or less.

The core material 7 is formed into a sheet-like or long-shaped liquid crystal polymer, and a conductor pattern 6 is provided on the surface. The liquid crystal polymer of the core material 7 may be the same as the liquid crystal polymer of the liquid crystal polymer film 4. A conductor pattern 6 is provided on at least one side of the core material 7. In the present embodiment, a case where the conductor pattern 6 is provided on one surface of the core material 7 and the metal foil 33 is provided on the other surface will be described. However, the metal foil 33 may not be provided on the other side.

For example, the rough surface of the metal foil is overlapped on both sides of the flaky liquid crystal polymer, and after the liquid crystal polymer is followed by the metal foil, the unnecessary portion of the single-sided metal foil is removed by etching to provide the conductor pattern 6, thereby obtaining Core material 7. On the surface of the core material 7 on which the conductor pattern 6 is provided, the portion where the liquid crystal polymer is exposed is transferred to etch the shape of the rough surface of the removed metal foil, and thus is formed into the rough surface 7a. Thereby, the adhesion to the bonding sheet 5 at the time of manufacturing the multilayer printed wiring board 2 can be further improved. The thickness of the core material 7 is, for example, 12 μm or more and 200 μm or less. The thickness of the conductor pattern 6 and the metal foil 33 is, for example, 5 μm or more and 70 μm or less.

Next, a specific manufacturing method of the multilayer printed wiring board 2 will be described. The manufacturing method of the multilayer printed wiring board 2 is a peeling process and a lamination process after the liquid-crystal polymer film 1 ( laminated body) with metal foil is manufactured.

In the stripping project, as shown in Figure 1B and Figure 1C, the second gold will be The genus foil 32 is peeled off from the liquid crystal polymer film 1 with a metal foil to form a one-side metal foil liquid crystal polymer film 10. Since the rough surface 32a of the second metal foil 32 is subjected to a mold release treatment to form the release layer 32c, the second metal foil 32 can be easily peeled off.

In the laminate process, as shown in FIG. 2A and FIG. 2B, the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 are sequentially superposed and heated and pressurized.

In the lamination process, the surface (the rough surface 4a) of the single-sided metal foil liquid crystal polymer film 10 on which the first metal foil 31 is not formed is superposed on one side of the bonding sheet 5, and the conductor pattern 6 of the core material 7 is provided. The face (including the rough face 7a) is superposed on the other face of the bonding sheet 5. The multilayer printed wiring board 2 is molded by heating and pressurizing for a predetermined period of time in a state of being overlapped as described above. The forming can be continuous or monolithic. In the continuous type, the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 are each formed into an elongated shape, and the one side is formed while being conveyed in the longitudinal direction. In the one-piece type, the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 are uniformly cut into a predetermined size to form one set, and one set is formed into one set.

In the molding conditions, for example, a pressure of 0.5 MPa or more and 6 MPa or less is applied at a temperature of 250 ° C or more and 350 ° C or less for 1 minute or more and 120 minutes or less.

The liquid crystal polymer constituting the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 is softened by heating and pressurization. Next, by the softened liquid crystal polymer, the single-sided metal foil liquid crystal polymer film 10 and The bonding sheets 5 are successively joined, and the bonding sheets 5 are followed by the core material 7. Thereafter, when the heating and the pressure are stopped and cooling is performed as needed, the softened liquid crystal polymer is solidified, and the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 are integrated, and as shown in FIG. 2B. The multilayer printed wiring board 2 is shown. In the present embodiment, a three-layer multilayer printed wiring board 2 is displayed.

The liquid crystal polymer constituting the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 is cured, and is formed as the insulating layer 8 in the multilayer printed wiring board 2. The conductor pattern 6 of the core material 7 is disposed inside the insulating layer 8 to form the inner layer pattern 6a.

The surface of the bonding sheet 5 is preferably a rough surface. However, even if the surface of the bonding sheet 5 is smooth, the one-side metal foil liquid crystal polymer film 10 has a roughened surface (rough surface 4a), so that the adhesion to the bonding sheet 5 is improved by the rough surface 4a. . Further, since the core material 7 has a roughened surface (rough surface 7a), the adhesion to the bonding sheet 5 is enhanced by the rough surface 7a. As described above, the interface 45 between the one-side metal foil liquid crystal polymer film 10 and the bonding sheet 5, and the interface 57 between the bonding sheet 5 and the core material 7 are sufficiently adhered, thereby suppressing interlayer peeling.

Here, the melting point of the liquid crystal polymer film 4 in the metal foil-attached liquid crystal polymer film 1 (that is, in the one-side metal foil liquid crystal polymer film 10) is preferably higher than the melting point of the bonding sheet 5. Further, the heating temperature of the laminate process is preferably lower than the melting point of the liquid crystal polymer film 4 in the liquid crystal polymer film 1 with metal foil attached, and higher than the melting point of the bonding sheet 5. Thereby, in maintaining the one-side metal foil liquid crystal polymer film 10 When the rough surface 4a of the surface of the liquid crystal polymer film 4 is formed in a roughened state, the bonding sheet 5 is softened. Therefore, the resin in the bonding sheet 5 flows to the concave portion of the rough surface 4a of the liquid crystal polymer film 4. As a result, a strong registration effect is obtained between the liquid crystal polymer film 4 and the bonding sheet 5, and the adhesion is enhanced.

If the multilayer printed wiring board 2 shown in Fig. 2B is applied, for example, by a subtractive method, the multilayer printed wiring board 2 shown in Fig. 2C can be obtained. The outer layer pattern 6b is formed by removing unnecessary portions of the first metal foil 31 and the metal foil 33 by etching. Further, a hole is drilled through the insulating layer 8, and plating is performed on the inner surface of the hole, thereby forming a through hole 9a that electrically connects the outer layer patterns 6b on both surfaces of the multilayer printed wiring board 2. Further, the insulating layer 8 is drilled until reaching the inner layer pattern 6a, and plating is performed on the inner surface of the hole, thereby forming a through hole 9b that electrically connects the inner layer pattern 6a and the outer layer pattern 6b.

As shown in the above description, this embodiment In the multilayer printed wiring board 2, the adhesion between the interface 45 and the interface 57 is strong, and delamination between layers can be suppressed. Further, since all of the insulating layer 8 is composed of a liquid crystal polymer, it is excellent in high frequency characteristics. Therefore, the multilayer printed wiring board 2 of the present embodiment can be used in a high-speed transmission device such as a smart phone, a tablet PC, a notebook PC, a network servo device, a digital camera, a video camera, or an in-vehicle device.

[Examples]

The present disclosure will be specifically described below by way of examples.

(Example 1) <Metal foil polymer film with metal foil>

Copper foil ("F2WS" manufactured by Furukawa Electric Co., Ltd., thickness: 12 μm) was prepared as the first metal foil 31.

"VECSTAR CT-Z" (thickness: 50 μm, melting point: 330 ° C) manufactured by KURARAY Co., Ltd. was prepared as the liquid crystal polymer film 4.

A copper foil (a ten-point average roughness Rz 4.8 μm and a thickness of 18 μm of the rough surface 32a) subjected to the release treatment on the rough surface 32a is prepared as the second metal foil 32.

Using the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32, a liquid crystal polymer film 1 with a metal foil was produced as follows.

As shown in FIG. 1A and FIG. 1B, the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 are sequentially stacked. At this time, the surface of the first metal foil 31 which is superposed on the liquid crystal polymer film 4 is the rough surface 31a, and the surface of the second metal foil 32 which is superposed on the liquid crystal polymer film 4 is the rough surface 32a. In the state of being overlapped as described above, the film was formed by heating and pressing at 330 ° C, 3 MPa, and 5 minutes, thereby obtaining a metal foil-attached liquid crystal polymer film 1 as shown in FIG. 1B.

<Multilayer printed wiring board>

"VECSTAR CT-F" (thickness: 50 μm, melting point: 280 ° C) manufactured by KURARAY Co., Ltd. was prepared as the bonding sheet 5.

The core material 7 is a copper foil on both sides of "VECSTAR CT-Z" (thickness: 100 μm, melting point: 330 ° C) manufactured by KURARAY Co., Ltd. After the "F2WS" manufactured by Kawasaki Electric Co., Ltd. and having a thickness of 12 μm), the conductive pattern 6 is provided by removing unnecessary portions of the single-sided metal foil by etching. The conductor pattern 6 is oxidized by a black oxidation treatment.

The multilayer printed wiring board 2 is produced by the above-described peeling process and laminate work using the metal foil-attached liquid crystal polymer film 1, the bonding sheet 5, and the core material 7.

In the peeling process, as shown in FIG. 1B and FIG. 1C, the second metal foil 32 is peeled off from the metal foil-attached liquid crystal polymer film 1, whereby the one-side metal foil liquid crystal polymer film 10 is produced. The peeling strength of the liquid crystal polymer film 4 and the second metal foil 32 was 0.08 N/mm.

In the laminate process, as shown in FIG. 2A and FIG. 2B, the one-side metal foil liquid crystal polymer film 10, the bonding sheet 5, and the core material 7 are sequentially superposed, and heated and pressurized. That is, the bonding foil 5 is sandwiched between the one-side metal foil liquid crystal polymer film 10 and the core material 7, and heating and pressurization are performed.

In the lamination process, the surface (the rough surface 4a) of the single-sided metal foil liquid crystal polymer film 10 on which the first metal foil 31 is not formed is superposed on one side of the bonding sheet 5, and the conductor pattern of the core material 7 is provided. The face of 6 (including the rough face 7a) is superposed on the other face of the bonding sheet 5. In the state of being overlapped as described above, heating and pressurization were carried out under molding conditions of 300 ° C, 1 MPa, and 10 minutes to obtain a multilayer printed wiring board 2 as shown in FIG. 2B. Since all of the insulating layers 8 of the multilayer printed wiring board 2 are composed of a liquid crystal polymer, they are excellent in high frequency characteristics.

(Example 2)

The copper foil having a ten-point average roughness Rz of 3.5 μm prepared as the rough surface 32a was prepared as the second metal foil 32 except for the second metal foil 32.

(Example 3)

The copper foil having a ten-point average roughness Rz of 2.1 μm prepared as the rough surface 32a was prepared as the second metal foil 32 except for the second metal foil 32.

(Example 4)

The copper foil having the ten-point average roughness Rz of the rough surface 32a of 1.3 μm was prepared as the second metal foil 32 except that it was the same as that of the first embodiment.

(Comparative Example 1)

The copper foil having the ten-point average roughness Rz of the rough surface 32a of 0.8 μm was prepared as the second metal foil 32 except that it was the same as that of the first embodiment.

(Comparative Example 2)

In addition to the preparation of the smooth surface 32b, the copper foil having a ten-point average roughness Rz of 2.1 μm is used as the second metal foil 32, and the first metal foil 31, the liquid crystal polymer film 4, and the second metal foil 32 are sequentially stacked. The second metal foil 32 is superposed on the surface of the liquid crystal polymer film 4 to form a smooth surface 32b, and is the same as that of the first embodiment. Here, as described above, the roughness of the second metal foil 32 can be controlled by adjusting the electrolysis conditions. Therefore, in Comparative Example 2, even if it is the smooth surface 32b, the ten-point average roughness Rz Increase to 2.1 μm. However, in Comparative Example 2, the rough surface 32a is also thicker than the smooth surface 32b.

(evaluation method)

In the multilayer printed wiring board 2 of the examples and the comparative examples obtained above, the adhesion force at the interface 45 between the one-side metal foil liquid crystal polymer film 10 and the bonding sheet 5 was measured. The adhesion is measured in accordance with JIS C 6471.

(evaluation result)

The evaluation results are shown in Table 1. Further, a photograph of the surface of the second metal foil 32 peeled off from the metal foil-attached liquid crystal polymer film 1 is shown in FIGS. 3 to 5. FIG. 3 and FIG. 4 are views showing photographs of the surface (rough surface 4a) of the second metal foil 32 separated from the liquid crystal polymer film 1 with metal foil obtained in the present embodiment. 3 shows the surface (rough surface 4a) of the liquid crystal polymer film 4 produced in Example 2, and FIG. 4 shows the surface (rough surface 4a) of the liquid crystal polymer film 4 produced in Example 4. FIG. 5 is a view showing a photograph of the surface (rough surface 4a) after the second metal foil 32 is peeled off from the liquid crystal polymer film 1 of the metal foil of Comparative Example 2. That is, Fig. 5 shows the surface of the liquid crystal polymer film 4 (rough surface 4a) produced in Comparative Example 2.

As a result of the evaluation, it is understood that the rough surface 32a of the copper foil as the second metal foil 32 is superposed on the liquid crystal polymer film 4, and in the first to fourth embodiments, the ten-point average roughness of the rough surface 32a is 1.3 μm or more. 4.8 μm or less, the adhesion between the liquid crystal polymer film 4 and the interface 45 of the bonding sheet 5 is good. it is good.

However, in Comparative Example 1 in which the ten-point average roughness of the rough surface 32a was 0.8 μm, the adhesion between the liquid crystal polymer film 4 and the interface 45 of the bonding sheet 5 was inferior to those of Examples 1 to 4.

Further, as shown in the comparative example 2, when the smooth surface 32b of the copper foil as the second metal foil 32 is superposed on the liquid crystal polymer film 4, even if the ten-point average roughness is 2.1 μm, the liquid crystal polymer film 4 and the bonding are performed. The adhesion of the interface 45 of the sheet 5 is also inferior to that of the first to fourth embodiments.

The ten-point average roughness Rz (2.1 μm) of the smooth surface 32b of Comparative Example 2 is larger than the ten-point average roughness Rz (1.3 μm) of the rough surface 32a of Example 4. However, in spite of this, the adhesion force of Comparative Example 2 was smaller than that of Example 4.

The smooth surface 32b of Comparative Example 2 is a surface in which the original of the electrolytic metal foil is in contact with the rotating drum as described above. In the rotating drum, when the drum is cleaned, a stripe-shaped grinding damage in a certain direction is generated on the surface of the drum. This polishing damage is transferred by forming a stripe-shaped groove or protrusion in a certain direction on the surface of the electrolytic metal foil. It is considered that the adhesion force of Comparative Example 2 is weakened by the stripe-shaped grooves or protrusions in the predetermined direction.

On the other hand, the rough faces 32a of Examples 1 to 4 are the faces of the electrolytic metal foil which are not in contact with the rotating drum. In the rough surface 32a, a pear-shaped unevenness which is not directional is formed. It is considered that the adhesion is improved by the unevenness.

As described above, according to the present disclosure, the surface of the liquid crystal polymer film 4 in the metal foil-attached liquid crystal polymer film 1 can be roughened without being etched. Further, by using the roughened surface, the adhesion of the metal foil-attached liquid crystal polymer film 1 to the bonding sheet 5 is improved.

4‧‧‧Liquid polymer film

31a, 32a‧‧‧

31‧‧‧1st metal foil

31b, 32b‧‧‧ smooth surface

32‧‧‧2nd metal foil

32c‧‧‧ release layer

40‧‧‧1st

41‧‧‧2nd

Claims (12)

A metal foil-attached liquid crystal polymer film comprising: a liquid crystal polymer film; a first metal foil laminated on a first surface of the liquid crystal polymer film; and a layer deposited on the liquid crystal polymer film The second metal foil of the second surface on the opposite side of the one surface, the second metal foil has an electrolytic metal foil having a rough surface and a smooth surface on the opposite side of the rough surface, and the coarseness of the second metal foil The surface and the second surface of the liquid crystal polymer film are laminated, and the rough surface is subjected to a mold release treatment. The liquid crystal polymer film with metal foil attached to the first aspect of the invention, wherein the tenth point average roughness of the rough surface of the second metal foil is 1.0 μm or more and 5.0 μm or less. The liquid crystal polymer film with metal foil attached to the first aspect of the invention, wherein the liquid crystal polymer film and the second metal foil have a peel strength of 0.01 N/mm or more and 0.4 N/mm or less. The liquid crystal polymer film with metal foil attached to the first aspect of the invention, wherein the rough surface has irregularities having no directivity. The liquid crystal polymer film with metal foil attached to the first aspect of the patent application, wherein the rough surface is not subjected to the fine particle adhesion treatment. A multilayer printed wiring board comprising: the second metal foil is provided with a metal foil as claimed in claim 1 a single-sided metal foil liquid crystal polymer film obtained by peeling off the liquid crystal polymer film; a bonding sheet of the liquid crystal polymer film laminated on the one-side metal foil liquid crystal polymer film; and having a conductor pattern and being laminated on the bonding The core material of the sheet, the surface of the bonding sheet opposite to the surface on which the liquid crystal polymer film is laminated, and the surface of the core material on which the conductor pattern is formed are laminated. A method for producing a liquid crystal polymer film with a metal foil, which is a first metal foil of a first area layer of a liquid crystal polymer film, and an anode electrode and a rotating drum as a cathode electrode are immersed in an electrolyte containing metal ions. An electric current flows between the anode electrode and the cathode electrode, whereby the second metal foil is electrodeposited on the surface of the rotating drum, and the second metal foil is peeled off from the rotating drum to separate the second metal foil. a surface that is in contact with the surface of the rotating drum is a shiny surface, and a surface of the second metal foil that is not in contact with the surface of the rotating drum is a rough surface, and the rough surface of the second metal foil is The release agent is applied, and the laminate is formed on the rough surface of the second metal foil on the second surface layer opposite to the first surface of the liquid crystal polymer film, and the laminate is pressurized. And heating. The method for producing a metal foil-attached liquid crystal polymer film according to claim 7, wherein the rough surface of the second metal foil is The ten point average roughness is 1.0 μm or more and 5.0 μm or less. The method for producing a metal foil-attached liquid crystal polymer film according to claim 7, wherein the rough surface has irregularities having no directivity. The method for producing a metal foil-attached liquid crystal polymer film according to claim 7, wherein the rough surface is not subjected to the fine particle adhesion treatment. A method for producing a multilayer printed wiring board, wherein the second metal foil is peeled off from a metal foil-attached liquid crystal polymer film according to any one of claims 1 to 5, and the second metal is used a surface on which the foil is peeled off is laminated, and a bonding sheet formed of a liquid crystal polymer is laminated, and a surface of the core material on which the conductor pattern is formed is superposed on a surface of the bonding sheet opposite to a surface on which the liquid crystal polymer film is laminated. A multilayer substrate is produced, and the multilayer substrate is pressurized and heated. The method for producing a multilayer printed wiring board according to claim 11, wherein the liquid crystal polymer film of the metal foil-attached liquid crystal polymer film has a melting point higher than a melting point of the bonding sheet, and the multilayer substrate The heating temperature is lower than the melting point of the liquid crystal polymer film in the liquid crystal polymer film attached to the metal foil, and is higher than the melting point of the bonding sheet.