WO2020066146A1

WO2020066146A1 - Low dielectric substrate

Info

Publication number: WO2020066146A1
Application number: PCT/JP2019/023076
Authority: WO
Inventors: 将義中村; 亮人松富; 慧三島
Original assignee: 日東電工株式会社
Priority date: 2018-09-28
Filing date: 2019-06-11
Publication date: 2020-04-02
Also published as: JP7082932B2; JP2020049904A; TW202026142A

Abstract

This low dielectric substrate comprises, in order in the direction of thickness, a porous resin layer and a metal layer, and further comprises a protective material disposed on one surface of either the porous resin layer or the metal layer. The Shore D hardness H1 at 23°C of the protective material and the Shore D hardness H2 at 23°C of the porous resin layer satisfy formula (1), or thickness T1 of the protective material and thickness T0 of the laminated material comprising the porous resin layer and metal layer satisfy formula (2). Formula (1): H1 < H2 Formula (2): T1 > 0.5 x T0

Description

Low dielectric substrate material

The present invention relates to a low dielectric substrate material, and more particularly, to a low dielectric substrate material suitably used for manufacturing a high-frequency antenna and a high-speed transmission substrate.

Conventionally, so-called “third generation (3G)” and “fourth generation (4G)” wireless communication standards have been widely used. However, in recent years, the communication capacity of image data and the like has tended to further increase (increase in capacity), and large-capacity data cannot be transmitted at a practical level in wireless communication of the above-described standard.

Therefore, the development of so-called "fifth generation (5G)" wireless communication is being promoted. Wireless communication of the "fifth generation (5G)" standard can transmit a large amount of data. Moreover, in the wireless communication of the "fifth generation (5G)" standard, the above data can be transmitted at a high speed. In recent years, the use of the "fifth generation (5G)" standard has been increasingly desired. It is rare.

Specifically, in the wireless communication of the “fifth generation (5G)” standard, a high frequency including a millimeter wave is used. This millimeter wave is easily attenuated by moisture in the atmosphere, and a substrate material having a low dielectric constant is required as a substrate material of a high-frequency antenna that emits a millimeter wave. When a low dielectric substrate material is used for the antenna, millimeter wave radio waves can be efficiently emitted. In addition, when a low dielectric antenna substrate material is used, the communication distance can be extended, the area of the antenna member can be reduced, and power consumption can be reduced.

In recent years, a high-speed FPC for transmitting data at a high speed has been required as an FPC (flexible printed circuit board), and a low-dielectric substrate material is also required as a substrate material for the high-speed FPC.

In order to meet the above-mentioned requirements, that is, as a substrate material for a large-capacity data wireless communication antenna or a high-speed FPC, a low dielectric substrate having a low dielectric constant is being developed. Substrates using a low-dielectric resin material such as such have been developed.

On the other hand, a substrate made of a porous material is also being studied. Since the porous body has air having the lowest dielectric constant 1 in the pores, the porous body has a relatively low dielectric constant. As a metal foil laminate having such a porous body, for example, a metal foil laminate having a resin porous layer as an insulating material and a metal foil disposed on the surface thereof has been proposed (for example, the following). See Patent Document 1.).

JP-A-2004-82372

However, the metal foil needs to be formed into a metal pattern with high precision in a later step.

方法 Further, a method for industrially producing a porous body having a low dielectric constant has not yet been established so far. In addition, a method for mass-producing the porous body at low cost is also required.

Accordingly, an object of the present invention is to provide a low-dielectric substrate material that can be formed on a metal pattern with high precision and that can be mass-produced industrially at low cost.

The present invention [1] includes a porous resin layer and a metal layer in the thickness direction, and further includes a protective material disposed on one surface of the porous resin layer and the metal layer. The Shore D hardness H1 of 23 ° C. and the Shore D hardness H2 of 23 ° C. of the laminate including the porous resin layer and the metal layer satisfy the following expression (1), or the thickness T1 of the protective material. And the thickness T0 of the laminated material includes a low dielectric substrate material satisfying the following expression (2).
H1 <H2 (1)
T1> 0.5 × T0 (2)
The present invention [2] includes the low-dielectric substrate material according to [1], wherein both of the expressions (1) and (2) are satisfied.

The present invention [3] includes the low dielectric substrate material according to [1] or [2], wherein the porosity of the porous resin layer is 60% or more.

In this low dielectric substrate material, since the Shore D hardness H1 of the protective material is lower than the Shore D hardness H2 of the porous resin layer or the thickness T1 of the protective material is larger than half the thickness T0 of the laminated material, When the dielectric material is wound, the protective material is sufficiently crushed, so that the porous resin layer can be prevented from being crushed. Therefore, a metal layer can be formed in a metal pattern with high precision.

Further, since the crushing of the porous resin layer is suppressed, a decrease in the porosity can be suppressed. Therefore, an increase in the dielectric constant of the porous resin layer can be suppressed. As a result, this low dielectric substrate material is extremely useful as a substrate material that can conform to the fifth generation (5G) standards and high-speed FPC.

低 Since the low dielectric substrate material has a metal layer, it can be patterned as an antenna corresponding to the fifth generation (5G) standard or a wiring of a high-speed FPC substrate. Specifically, even if the metal layer is patterned under etching conditions that can be mass-produced industrially, an antenna or wiring of a high-speed FPC board that can conform to the fifth generation (5G) can be formed with excellent accuracy.

In addition, when the porous resin layer has a high ratio of closed cell structures, it is possible to suppress a decrease in pattern accuracy due to penetration of an etching solution used for patterning. Therefore, the low dielectric substrate material is useful as a substrate material that can sufficiently and surely cope with fifth-generation (5G) wireless communication and high-speed FPC.

Furthermore, since the low dielectric substrate material includes a protective material disposed in the thickness direction with respect to the porous resin layer, even when the low dielectric substrate material is manufactured by being stacked in the thickness direction as an industrial manufacturing condition, In addition, the protective material suppresses a decrease in the porosity caused by the porous resin layer being pressed in the thickness direction, and therefore, it is possible to sufficiently ensure a low dielectric constant of the porous resin layer. . As a result, the low dielectric substrate material is mass-produced at low cost.

FIG. 1 shows a cross-sectional view of one embodiment of the low dielectric substrate material of the present invention. FIG. 2 shows a cross-sectional view of a pattern laminate obtained from the low dielectric substrate material shown in FIG. FIG. 3 is a cross-sectional view of a modified example of the low dielectric substrate material (an embodiment without the first protective material). FIG. 4 shows a cross-sectional view of a modified example of the low dielectric substrate material (an embodiment having no adhesive layer). FIG. 5 is a cross-sectional view of a modified example of the low dielectric substrate material (an aspect in which the first protective material is not provided, but the second protective material and the laminated material are provided). FIG. 6 is a cross-sectional view of a modified example of the low dielectric substrate material (an aspect in which the second protective material is not provided, but the first protective material and the laminated material are provided).

<One embodiment>
One embodiment of the low dielectric substrate material of the present invention will be described with reference to FIGS.

[Basic aspect]
First, a layer configuration, a manufacturing method, a usage method, and the like, which are basic aspects of the low dielectric substrate material 1, will be described in order.

(Low dielectric substrate material and its layer structure)
As shown in FIG. 1, the low dielectric substrate material 1 has one surface and the other surface facing each other in the thickness direction, and has a shape extending in a surface direction orthogonal to the thickness direction.

The low dielectric substrate material 1 is disposed on a first metal layer 3, a porous resin layer 4 disposed on one surface in the thickness direction of the first metal layer 3, and disposed on one surface in a thickness direction of the porous resin layer 4. A first metal layer that is provided on one surface in the thickness direction of the adhesive layer; and a second metal layer that is an example of a metal layer disposed on one surface of the first metal layer in the thickness direction. The protective device includes a protective material 2 and a second protective material 7 as an example of a protective material disposed on one surface in the thickness direction of the second metal layer 6. That is, the low dielectric substrate material 1 includes the first protective material 2, the first metal layer 3, the porous resin layer 4, the adhesive layer 5, the second metal layer 6, and the second protective material 7 having a thickness. The direction is provided in order from the other side to one side. Preferably, the low dielectric substrate material 1 includes only the first protective material 2, the first metal layer 3, the porous resin layer 4, the adhesive layer 5, the second metal layer 6, and the second protective material 7. Is provided.

[First metal layer]
The first metal layer 3 has one surface and the other surface facing each other in the thickness direction, and has a sheet (plate) shape extending in the surface direction. The material of the first metal layer 3 is not particularly limited, and examples thereof include copper, iron, silver, gold, aluminum, nickel, and alloys thereof (stainless steel, bronze). Preferably, copper is used. The thickness of the first metal layer 3 is, for example, 0.1 μm or more, preferably 1 μm or more, and is, for example, 100 μm or less, preferably 50 μm or less.

(Porous resin layer)
The porous resin layer 4 has one surface and the other surface opposed in the thickness direction, and has a substantially plate (sheet) shape extending in the surface direction. The other surface of the porous resin layer 4 is in contact (close contact) with one surface of the first metal layer 3.

The porous resin layer 4 has many fine pores (pores) 10. The porous resin layer 4 has, for example, one of a closed cell structure and an open cell structure. Preferably, it mainly has a closed cell structure. In this case, the ratio of the closed cells is, for example, more than 50%, preferably 80% or more, more preferably 90% or more, and for example, 100%. %. When the ratio of the closed cells exceeds the above lower limit, a decrease in pattern accuracy due to the penetration of the etching solution used for patterning the first metal layer 3 and the second metal layer 6 into the porous resin layer 4 is suppressed. be able to.

空 The porosity of the porous resin layer 4 is, for example, 60% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably 85% or more. In addition, the porosity of the porous resin layer 4 is, for example, less than 100%, and further, 99% or less. The porosity is determined, for example, by image analysis of a cross-sectional SEM photograph of the porous resin layer 4. Alternatively, the porosity is determined by calculation based on the following equation.

Porosity (%) = (1−specific gravity of non-porous resin layer / specific gravity of porous resin layer) × 100
In the formula, the non-porous resin layer is made of the material of the porous resin layer 4, but is not porous but a dense film.

(4) When the porosity of the porous resin layer 4 is equal to or more than the lower limit described above, the porous resin layer 4 can have a low dielectric constant that can sufficiently cope with the fifth generation (5G) standard and high-speed FPC. Specifically, as described above, the low dielectric substrate material 1 is useful as a substrate material that can sufficiently comply with the fifth generation (5G) standard and high-speed FPC.

平均 The average diameter of the pores 10 in the porous resin layer 4 (that is, the average pore diameter) is, for example, 10 μm or less, and is, for example, 0.1 μm or more. The average pore diameter is determined by image analysis of a cross-sectional SEM photograph of the porous resin layer 4. In the image analysis, binarization is performed on the SEM image, the holes 10 are identified, the hole diameter is calculated, and a histogram is formed. In the image analysis, ImageJ is used as analysis software.

The dielectric constant of the porous resin layer 4 at a frequency of 60 GHz is appropriately adjusted depending on the porosity and the type of the resin described below, and specifically, is, for example, 2.5 or less, preferably 2.0 or less, Also, for example, it is more than 1.0. The dielectric constant of the porous resin layer 4 is actually measured by a resonator method using a frequency of 60 GHz.

If the dielectric constant of the porous resin layer 4 is equal to or less than the above upper limit, the low dielectric substrate material 1 has a low dielectric constant, and is useful as a fifth generation (5G) standard or a high-speed FPC substrate material. Can be used.

材料 The material of the porous resin layer 4 is not particularly limited, and examples thereof include resins such as a thermosetting resin and a thermoplastic resin.

As the thermosetting resin, for example, polycarbonate resin, thermosetting polyimide resin, thermosetting fluorinated polyimide resin, epoxy resin, phenol resin, urea resin, melamine resin, diallyl phthalate resin, silicone resin, thermosetting urethane resin , A fluororesin (a polymer of a fluorine-containing olefin (specifically, polytetrafluoroethylene (PTFE) or the like)), a liquid crystal polymer (LCP), or the like. These can be used alone or in combination of two or more.

Examples of the thermoplastic resin include olefin resin, acrylic resin, polystyrene resin, polyester resin, polyacrylonitrile resin, maleimide resin, polyvinyl acetate resin, ethylene-vinyl acetate copolymer, polyvinyl alcohol resin, polyamide resin, and polyvinyl chloride. Resin, polyacetal resin, polyphenylene oxide resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, polyether ether ketone resin, polyallyl sulfone resin, thermoplastic polyimide resin, thermoplastic fluorinated polyimide resin, thermoplastic urethane resin, poly Examples include ether imide resin, polymethylpentene resin, cellulose resin, liquid crystal polymer, and ionomer. These can be used alone or in combination of two or more.

Among the above resins, from the viewpoint of mechanical strength, preferably, polyimide resin (including thermosetting polyimide resin and thermoplastic polyimide resin), fluorinated polyimide resin (thermosetting fluorinated polyimide resin and thermoplastic fluorinated polyimide resin) Resins), polycarbonate resins and polyetherimide resins. Preferably, a polyimide resin is used. The polyimide resin is included in the manufacturing process of the low dielectric substrate material 1 including the porous resin layer 4 having a closed cell structure, and is a material most suitable for lamination by pressing (pressing). The details of the above-mentioned preferable physical properties of the resin and the manufacturing method thereof are described in, for example, JP-A-2018-021171, JP-A-2018-021172, and the like.

The porous resin layer 4 can have a skin layer (not shown) formed on one surface and the other surface in the thickness direction.

厚み The thickness of the porous resin layer 4 is, for example, 2 μm or more, preferably 5 μm or more, and for example, 1,000 μm or less, preferably 500 μm or less.

The layers other than the porous resin layer 4, specifically, the first metal layer 3, the adhesive layer 5 (described later), the second metal layer 6 (described later), the first protective material 2 (described later), and the second protective layer Each of the materials 7 (described later) is different from the porous resin layer 4 and is, for example, non-porous, that is, has substantially no fine pores and is dense.

(Adhesive layer)
The adhesive layer 5 has a sheet shape along the surface direction on one surface in the thickness direction of the porous resin layer 4.

The material of the adhesive layer 5 is not particularly limited, and includes various types of adhesives such as a hot melt type adhesive and a thermosetting type adhesive. Specifically, an acrylic type adhesive, an epoxy type adhesive And silicone-based adhesives. The thickness of the adhesive layer 5 is, for example, 2 μm or more, preferably 5 μm or more, and for example, 50 μm or less, preferably 25 μm or less, more preferably from the viewpoint of reducing the dielectric constant of the low dielectric substrate material 1. , 10 μm or less.

[Second metal layer]
The second metal layer 6 has one surface and the other surface facing each other in the thickness direction, and has a sheet (plate) shape extending in the surface direction. The other surface of the second metal layer 6 is adhered to one surface of the porous resin layer 4 via the adhesive layer 5. The material and thickness of the second metal layer 6 are the same as those of the first metal layer 3.

(Laminated material)
The first metal layer 3, the porous resin layer 4, the adhesive layer 5, and the second metal layer 6 constitute a laminated material 14. In other words, the laminate 14 includes the first metal layer 3, the porous resin layer 4, the adhesive layer 5, and the second metal layer 6 in this order in the thickness direction.

厚み The thickness T0 of the laminated material 14 is set so as to satisfy a desired ratio with the thickness T1 of the second protective material 7 described later. Specifically, the thickness T0 of the laminated material 14 is, for example, 1 μm or more, preferably 5 μm or more, and is, for example, 10 μm or less, preferably 500 μm or less.

[First protective material]
The first protective material 2 forms the other surface in the thickness direction of the low dielectric substrate material 1. The first protective member 2 has one surface and the other surface facing each other in the thickness direction, and has a sheet shape extending in a surface direction orthogonal to the thickness direction. One surface of the first protective material 2 is in releasable contact (close contact) with the other surface of the first metal layer 3.

(4) The first protective material 2 protects the first metal layer 3. Specifically, the first protective material 2 covers the first metal layer 3 before patterning the first metal layer 3, while the first protective material 2 covers the first metal layer 3 when patterning the first metal layer 3. 3 is a release sheet (first release sheet) to be peeled off. Note that, as shown in FIG. 2, the first protective material 2 is not disposed on the other-side wiring 18 (described later) formed by patterning the first metal layer 3.

The first protective material 2 is a protective sheet provided on the low dielectric substrate material 1 in order to industrially mass-produce the low dielectric substrate material 1 having the porous resin layer 4 having a high porosity.

The material of the first protection member 2 is not particularly limited, and examples thereof include a polymer and a metal. Examples of the polymer include polyolefins such as polyethylene (PE) and polypropylene, and polyesters such as polyethylene terephthalate (PET). Examples of the metal include aluminum, iron, and alloys (such as stainless steel).
Preferably, the material of the first protective material 2 is a polymer. The thickness of the first protective material 2 is, for example, 1 μm or more, preferably 10 μm or more, and is, for example, 2,000 μm or less, preferably 1,000 μm or less.

[Second protective material]
The second protective material 7 forms one surface in the thickness direction of the low dielectric substrate material 1. The second protection member 7 has one surface and the other surface facing each other in the thickness direction, and has a sheet shape extending in a surface direction orthogonal to the thickness direction. The other surface of the second protection member 7 is in releasable contact (close contact) with one surface of the second metal layer 6.

(4) The second protection member 7 protects the second metal layer 6. Specifically, the second protective material 7 covers the second metal layer 6 before patterning the second metal layer 6, while the second protective material 7 covers the second metal layer 6 when patterning the second metal layer 6. As shown by the line, a release sheet (second release sheet) that is released from the second metal layer 6. As shown in FIG. 2, the second metal layer 6 is not disposed on the one-side wiring 17 (described later) formed by patterning the second metal layer 6.

The second protective material 7 is a protective sheet provided on the low dielectric substrate material 1 together with the first protective material 2 in order to industrially mass-produce the low dielectric substrate material 1 including the porous resin layer 4 having a high porosity. It is.

形状 The shape, material, thickness, etc. of the second protection member 7 are the same as those of the first protection member 2.

The thickness of the low dielectric substrate material 1 depends on the total thickness of the first protective material 2, the first metal layer 3, the porous resin layer 4, the adhesive layer 5, the second metal layer 6, and the second protective material 7 (that is, the laminated material). 14, the total thickness of the first protective material 2 and the second protective material 7), for example, 10 μm or more, preferably 20 μm or more, more preferably 200 μm or more, and for example, 5,000 μm or less, Preferably, it is 2,000 μm or less.

(Production method of low dielectric substrate material)
Next, a method of manufacturing the low dielectric substrate material 1 will be described.

In the manufacture of the low dielectric substrate material 1 according to one embodiment, for example, each member is stacked (formed) while being conveyed by a roll-to-roll method.

Specifically, first, the first metal layer 3 is prepared. For example, a foil (metal foil) made of the above-described material is prepared as the first metal layer 3.

Next, the porous resin layer 4 is formed on one surface of the first metal layer 3. For example, the porous resin layer 4 is formed (built) on one surface of the first metal layer 3.

Specifically, first, a varnish containing the above-described resin precursor, a porogen, a nucleating agent, and a solvent is prepared, and then, the varnish is applied to one surface of the first metal layer 3 to be applied. Form a film. The types, blending ratios, and the like of the porosity, nucleating agent, and solvent in the varnish are described in, for example, JP-A-2018-021171, JP-A-2018-021172, and the like.

In particular, the number of parts by mass (mixing ratio) of the porogen is preferably 20 parts by mass or more, more preferably 50 parts by mass or more, and preferably 300 parts by mass with respect to 100 parts by mass of the precursor. Or less, more preferably 250 parts by mass or less.

The nucleating agent is a foaming nucleating agent (cell regulator) that becomes a nucleus when the precursor is foamed (porous). As the nucleating agent, in addition to the nucleating agent (PTFE and the like) described in the above publication, a fluororesin (polymer of fluorinated olefin) such as poly (chlorotrifluoroethylene), and further, as a monomer unit, (meth) ) Copolymers containing acrylic acid esters and the above-mentioned fluorine-containing olefins are also included.

(4) The nucleating agent may be in a solid state, a liquid state, or a semi-solid state at room temperature (23 ° C.), and is preferably in a solid state. If the nucleating agent is solid at room temperature, examples of the shape of the nucleating agent include a substantially spherical shape, a substantially plate shape, a substantially needle shape, and an indefinite shape (including a lump shape). No.

If the nucleating agent is solid at room temperature, the average value of the maximum length of the nucleating agent (if it is substantially spherical, the average particle diameter) is, for example, 2,000 nm or less, preferably 1,000 nm or less. And, for example, 1 nm or more.

核 The nucleating agent may be prepared in advance as a slurry dispersed in a solvent (PTFE).

(4) Thereafter, by drying the coating film by heating, a phase separation structure of a precursor and a porogen with a nucleating agent as a nucleus is formed while the removal of the solvent proceeds.

(4) Then, the porogen is extracted from the precursor (pulled out or removed) by, for example, a supercritical extraction method using supercritical carbon dioxide as a solvent.

Then, the precursor is cured to form a resin and a resin having porosity, specifically, the porous resin layer 4.

Then, the adhesive layer 5 is disposed on one surface of the porous resin layer 4. For example, an adhesive is applied to one surface of the porous resin layer 4, or an adhesive layer 5 previously formed into a sheet from the adhesive is attached to one surface of the porous resin layer 4.

Next, the second metal layer 6 is disposed on one surface of the adhesive layer 5. For example, a foil (metal foil) made of the above-described material is attached to one surface of the adhesive layer 5.

Then, the first protection member 2 is disposed on the other surface of the first metal layer 3, and the second protection member 7 is disposed on one surface of the second metal layer 6. In addition, the second metal layer 6 on which the second protective material 7 is arranged in advance can be attached to the adhesive layer 5.

により Thereby, the low dielectric substrate material 1 is manufactured.

The application of the low dielectric substrate material 1 includes, for example, various applications. Preferably, the low dielectric substrate material 1 is used for manufacturing a high-frequency antenna or a high-speed transmission substrate (such as a high-speed transmission FPC) conforming to the fifth generation (5G) standard. Specifically, the low dielectric substrate material 1 is used as a substrate material for a high-frequency antenna or a high-speed FPC.

When the low dielectric substrate material 1 is used for the above purpose, for example, first, the second protective material 7 is peeled off from the second metal layer 6 as shown by the imaginary line in FIG. One surface of the two metal layers 6 is exposed. Before the second protective material 7 is peeled off from the second metal layer 6, the second protective material 7 is previously placed between the second protective material 7 and the second metal layer 6 at the end of the low dielectric substrate material 1. A cut (gap) serving as a trigger for peeling is provided, and an end of the second protection member 7 is gripped. Then, the second protection member 7 is peeled off from the second metal layer 6 while holding the end of the second protection member 7 and pulling the end to one side in the thickness direction.

Subsequently, the second metal layer 6 is patterned by photolithography (for example, a subtractive method) as shown in FIG. 2 so that, for example, one side of signal wiring (differential wiring or the like) or antenna wiring or the like is formed. The wiring 17 is formed.

After that, the first protective material 2 is peeled off from the first metal layer 3 to expose the other surface of the first metal layer 3, and then the first metal layer 3 is patterned by photolithography. For example, the other-side wiring 18 such as a ground wiring is formed.

As a result, a pattern laminated material 13 having the other side wiring 18, the porous resin layer 4, the adhesive layer 5, and the one side wiring 17 sequentially in the thickness direction is manufactured. Provided on high-frequency antennas and high-speed transmission boards conforming to (5G) standards.

And this low dielectric substrate material 1 has a porous resin layer 4, and the porous resin layer 4 is 60% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably, When it has a high porosity of 85% or more, it can have a sufficiently low low dielectric constant. Specifically, the low dielectric constant is, for example, 2.5 or less, preferably 2.0 or less. Accordingly, the low dielectric substrate material 1 can have a low dielectric constant that can be used for an antenna substrate for wireless communication of the fifth generation (5G) standard or high-speed FPC.

Further, since the low dielectric substrate material 1 includes the first metal layer 3 and the second metal layer 6, it can be patterned as an antenna corresponding to the fifth generation (5G) standard or a wiring of a high-speed FPC board. . Specifically, even if the first metal layer 3 and the second metal layer 6 are patterned under industrial etching conditions, the wiring of the antenna or the high-speed FPC board that can be adapted to the fifth generation (5G) is excellent. It can be formed with high precision.

In the case where the porous resin layer 4 has a closed cell structure, and the ratio of the closed cells is more than 50%, further, 80% or more, and further, as high as 90% or more, patterning is performed. It is possible to suppress a decrease in pattern accuracy due to the penetration of the used etching solution. Therefore, the low dielectric substrate material 1 is useful as a substrate material that can sufficiently and surely cope with fifth-generation (5G) wireless communication and high-speed FPC.

Further, since the low dielectric substrate material 1 includes the first protective material 2 and the second protective material 7 disposed on both sides in the thickness direction with respect to the porous resin layer 4, the low dielectric substrate material is used as an industrial manufacturing condition. Also when the first protective material 2 and the second protective material 7 are manufactured by being stacked in the thickness direction, the porosity of the first protective material 2 and the second protective material 7 increases due to the porous resin layer 4 being pressed in the thickness direction. Therefore, a low dielectric constant of the porous resin layer 4 can be sufficiently ensured. As a result, the low dielectric substrate material 1 is useful as a substrate material having a low dielectric constant enough to cope with the fifth generation (5G) standard and high-speed FPC while being mass-produced at low cost.

If the porosity of the porous resin layer 4 is equal to or less than the above upper limit, the porous resin layer 4 can secure sufficient mechanical strength.

<Outstanding features>
Next, salient features of the low dielectric substrate material 1 will be described in detail with reference to FIG. In FIG. 1, in the parentheses of the reference numerals, those starting from H mean the Shore D hardness of the layer at 23 ° C.

The Shore D hardness H1 at 23 ° C. of the second protective material 7 and the Shore D hardness H2 at 23 ° C. of the porous resin layer 4 satisfy the following expression (1), or the thickness T1 of the second protective material 7 And the thickness T0 of the laminated material 14 satisfies the following expression (2).
H1 <H2 (1)
T1> 0.5 × T0 (2)
When at least the Shore D hardness H1 at 23 ° C. of the second protective material 7 and the Shore D hardness H2 at 23 ° C. of the porous resin layer 4 satisfy the expression (1), the second protective material 7 is moved in the thickness direction. By being sufficiently crushed, it is possible to suppress the porous resin layer 4 from being crushed in the thickness direction. As a result, an increase in the dielectric constant of the porous resin layer 4 can be suppressed. Therefore, this low dielectric substrate material 1 is extremely useful as a substrate material that can conform to the fifth generation (5G) standards and high-speed FPC.

The Shore D hardness of each of the first metal layer 3, the adhesive layer 5, and the second metal layer 6 does not significantly contribute to the Shore D hardness of the laminated material 14 including them. Therefore, the Shore D hardness of the laminated material 14 and the Shore D hardness H2 of the porous resin layer 4 are substantially the same.

When the Shore D hardness H1 of the second protective material 7 is higher than the Shore D hardness H2 of the porous resin layer 4, the laminated material 14 (substantially, before the second protective material 7 is crushed). As a result, the porous resin layer 4) is crushed, and as a result, the porosity decreases, and the dielectric constant of the porous resin layer 4 increases. In this case, there is a case where the substrate material is not sufficient as a substrate material that can conform to the fifth generation (5G) standard or high-speed FPC.

When the Shore D hardness H1 of the second protective material 7 is the same as the Shore D hardness H2 of the porous resin layer 4, the second protective material 7 and the porous resin layer 4 are similarly crushed. After all, the increase in the dielectric constant of the porous resin layer 4 cannot be suppressed. In that case, there is a case where the substrate material is not sufficient as a substrate material that can conform to the fifth generation (5G) standard and the high-speed FPC.

However, as described above, when the Shore D hardness H1 of the second protective material 7 is higher than the Shore D hardness H2 of the porous resin layer 4, or when the Shore D hardness H1 of the second protective material 7 and the porous resin Even when the Shore D hardness H2 of the layer 4 is the same (that is, even when the above-mentioned formula (1) is not satisfied), if the following formula (2) regarding the thickness is satisfied, the second step in the manufacturing process Even when the second protective material 7 is wound, the amount by which the second protective material 7 is crushed can be ensured, and the crushing of the porous resin layer 4 can be suppressed. Therefore, the second metal layer 6 and the first metal layer 3 in the second protection member 7 can be formed in the metal pattern (the one-side wiring 17 and the other-side wiring 18 in FIG. 2) with high precision.

Also, since the crushing of the porous resin layer 4 is suppressed, a decrease in porosity can be suppressed. Thereby, an increase in the dielectric constant of the porous resin layer 4 in the laminated material 14 can be suppressed, and the low dielectric substrate material 1 is extremely useful as a substrate material that can conform to the fifth generation (5G) standard and high-speed FPC. be able to.

Further, the Shore D hardness H1 of the second protective material 7 and the Shore D hardness H2 of the porous resin layer 4 preferably satisfy the following expression (1-1), and preferably satisfy the following expression (1-2). ) Is satisfied, preferably the following expression (1-3) is satisfied, and for example, the following expression (1-4) is satisfied.
H1 <0.9 × H2 (1-1)
H1 <0.7 × H2 (1-2)
H1 <0.5 × H2 (1-3)
0.001 × H2 <H1 (1-4)
Further, regarding the formula (2), when the thickness T1 of the second protective material 7 is relatively thin, even if the second protective material 7 is crushed first, the crushed amount (room) Therefore, the laminated material 14 may be crushed after the second protective material 7 is substantially completely crushed.

However, in this low dielectric substrate material 1, when at least the thickness T1 of the second protective material 7 and the thickness T0 of the laminated material 14 satisfy Expression (2), the thickness T1 of the second protective material 7 is Since it is thicker than the half value of the thickness T0 of the member 14, the amount (room) that the second protective member 7 is crushed can be sufficiently secured. Therefore, before the laminated material 14 is crushed, the second protective material 7 is sufficiently crushed. Therefore, an increase in the dielectric constant of the porous resin layer 4 in the laminated material 14 can be suppressed, and this low dielectric substrate material 1 is extremely useful as a substrate material that can conform to the fifth generation (5G) standards and high-speed FPC.

Further, in the low dielectric substrate material 1, the thickness T1 of the second protective material 7 and the thickness T0 of the laminated material 14 more preferably satisfy the following expression (2-1), and more preferably the following expression (2-1). It satisfies (2-2), particularly preferably satisfies the following formula (2-3), satisfies the following formula (2-4), and further satisfies the following formula (2-5).
T1> 0.75 × T0 (2-1)
T1> 0.9 × T0 (2-2)
T1> T0 (2-4)
1.25 × T0 <T1 <10 × T0 (2-5)
If the second protective material 7 and the laminated material 14 satisfy the above expression, an increase in the dielectric constant of the porous resin layer 4 in the laminated material 14 can be further suppressed, and the low dielectric substrate material 1 is a fifth generation (5G) ) Is extremely useful as a substrate material that can conform to the standards and high-speed FPC.

Also, more preferably, both the expressions (1) and (2) are satisfied. If both the formulas (1) and (2) are satisfied, the second protective member 7 is crushed even more sufficiently. Therefore, an increase in the dielectric constant of the porous resin layer 4 in the laminated material 14 can be further suppressed.

<Modification>
Next, a modified example of the embodiment will be described. In the following modified examples, the same members and steps as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. Further, one embodiment and each modified example can be appropriately combined. Further, each modified example can exhibit the same operational effects as those of the embodiment, except where otherwise noted.

In the above description, the low dielectric substrate material 1 is manufactured by roll-to-roll. However, the present invention is not limited to this. For example, the low dielectric substrate material 1 can be manufactured by a batch method (single wafer type).

In one embodiment, first, the first protection member 2 is separated from the first metal layer 3 and then the second protection member 7 is separated from the second metal layer 6, but the order may be reversed. Also, they may be simultaneous.

一方 One surface and / or the other surface of the second protective material 7 may be subjected to a peeling treatment or an adhesive treatment. Note that the thickness of the release layer or the adhesive layer is set to such an extent that the Shore D hardness H1 of the second protective material 7 does not substantially vary.

In one embodiment, as shown in FIG. 1, the adhesive layer 5 is interposed between the porous resin layer 4 and the second metal layer 6, but is not limited thereto. 1 It may be interposed between the metal layer 3 and the porous resin layer 4.

In one embodiment, the second protective material 7 is illustrated as an example of the protective material of the present invention, and the Shore D hardness H1 or the thickness T1 of the second protective material 7 satisfies the above formula (1) or formula (2). However, for example, in addition to the second protection member 7, the first protection member 2 can be further exemplified as an example of the protection member. In this case, the Shore D hardness H3 of the first protective material 2 and the Shore D hardness H2 of the porous resin layer 4 satisfy the following expression (3), or the thickness T1 of the first protective material 2 The thickness T1 of the laminated material 14 satisfies the following expression (2).
H3 <H2 (3)
T1> 0.5 × T0 (2)
The thickness T1 of the first protection member 2 is the same as the thickness T1 of the second protection member 7.

Regarding the Shore D hardness H3 of the first protective material 2 and the Shore D behavior H2 of the porous resin layer 4, preferably, the following formula (3-1) is satisfied, and more preferably, the following formula (3-2) Is satisfied, more preferably the following formula (3-3) is satisfied, and particularly preferably the following formula (3-4) is satisfied.
H3 <0.9 × H2 (3-1)
H3 <0.7 × H2 (3-2)
H3 <0.5 × H2 (3-3)
0.001 × H2 <H3 (3-4)
The Shore D hardness H3 of the first protection member 2 may be the same as the Shore D hardness H1 of the second protection member 7.

More preferably, both the expressions (3) and (2) are satisfied.

Note that one surface and / or the other surface of the first protective material 2 may be subjected to a peeling treatment or an adhesive treatment. The thickness of the release layer or the pressure-sensitive adhesive layer is set to a value that does not substantially change the Shore D hardness H3 of the first protective material 2.

Alternatively, in one embodiment, the low dielectric substrate material 1 includes the first protective material 2, but may include the second protective material 7 without the first protective material 2 as illustrated in FIG. 3.

低 This low dielectric substrate material 1 includes a laminated material 14 and a second protective material 7. Specifically, the first metal layer 3, the porous resin layer 4, the adhesive layer 5, the second metal layer 6, and the second protective material 7 are sequentially provided toward one side in the thickness direction.

The first metal layer 3 is exposed toward the other side in the thickness direction. The other surface in the thickness direction of the first metal layer 3 is in contact with one surface in the thickness direction of the second protective material 7 when a plurality of low dielectric substrate materials 1 are stacked (laminated) in the thickness direction. It is protected by the second protection member 7.

Also, in one embodiment, as shown in FIG. 1, the low-dielectric substrate material 1 includes the adhesive layer 5, but may not include the adhesive layer 5, as illustrated in FIG.

では In the low dielectric substrate material 1, the laminated material 14 includes the first metal layer 3, the porous resin layer 4, and the second metal layer 6 in this order in the thickness direction. In other words, the low dielectric substrate material 1 includes the first protective material 2, the first metal layer 3, the porous resin layer 4, and the second metal layer 6 in this order in the thickness direction.

Furthermore, as shown in FIG. 5, the low dielectric substrate material 1 does not need to include the first protective material 2 and the first metal layer 3. In this low dielectric substrate material 1, a laminated material 14 having a porous resin layer 4 and a second metal layer 6 and a second protective material 7 are sequentially arranged toward one side in the thickness direction. Specifically, the low dielectric substrate material 1 includes a porous resin layer 4, a second metal layer 6, and a second protective material 7 in order toward one side in the thickness direction.

The porous resin layer 4 forms the other surface in the thickness direction of the low dielectric substrate material 1 and is exposed toward the other side in the thickness direction. When a plurality of low dielectric substrate materials 1 are stacked (laminated) in the thickness direction, the porous resin layer 4 is in contact with one surface in the thickness direction of the second protection material 7, that is, protected by the second protection material 7. Is done.

In the modified example shown in FIG. 5, the laminated material 14 and the second protective material 7 are arranged in order toward one side in the thickness direction, but in the modified example shown in FIG. 6, the first protective material as an example of the protective material is provided. 2 and the laminated material 14 are sequentially arranged toward one side in the thickness direction.

(6) As shown in FIG. 6, the low dielectric substrate material 1 includes a first protective material 2, a porous resin layer 4, and a second metal layer 6 in this order in the thickness direction.

In the modification shown in FIG. 6, the second metal layer 6 forms one surface in the thickness direction of the low dielectric substrate material 1 and is exposed toward one side in the thickness direction. The second metal layer 6 is in contact with the other surface in the thickness direction of the first protective material 2 when the low dielectric substrate materials 1 are stacked (laminated) in the thickness direction, that is, protected by the first protective material 2. Is done.

Moreover, the porous resin layer 4 may be composed of a plurality of layers, such as two or three or more layers.

実施 Examples and comparative examples are shown below to further illustrate the present invention. In addition, this invention is not limited to an Example and a comparative example at all. Specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the mixing ratios (corresponding to them) described in the above-mentioned “Embodiments of the Invention”. The upper limit (values defined as “less than” or “less than”) or the lower limit (values defined as “over” or “exceeding”), such as the content ratio, physical property values, and parameters, may be substituted. it can.

<Manufacture of low dielectric substrate material corresponding to FIG. 3>
Example 1
First, a 12.5 μm-thick first metal foil 3 made of copper was prepared.

Next, 4.2 parts by mass of an imidation catalyst (2-methylimidazole) and polyoxyethylene dimethyl ether (Nippon Oil Co., Ltd. grade: 100 parts by mass) in 100 parts by mass of the polyimide precursor solution described in Reference Example of JP-A-2018-021172: A varnish is prepared by blending 200 parts by weight of a porogen comprising MM400, weight average molecular weight 400), 3 parts by weight of a nucleating agent comprising PTFE having an average particle diameter of 1,000 nm or less, and NMP (N-methylpyrrolidone). did. The nucleating agent was prepared in advance as a slurry dispersed in NMP and blended with the polyimide precursor. The total number of NMP in the varnish was adjusted so as to be 150 parts by mass with respect to 100 parts by mass of the polyimide precursor, including those contained in the slurry.

This varnish is applied to one surface of the first metal foil 3 and dried at 120 ° C. for 30 minutes to remove NMP. Subsequently, the porosity is removed by supercritical extraction, and then the vacuum is applied. The resultant was heated at 380 ° C. for 2 hours to be imidized, and a porous resin layer 4 made of polyimide was formed on one surface of the first metal foil 3.

The thickness of the porous resin layer 4 was 120 μm. The porosity of the porous resin layer 4 was 80%, and the average pore diameter was 7 μm. The dielectric constant of the porous resin layer 4 at a frequency of 60 GHz was 1.5. Further, the Shore D hardness H2 of the porous resin layer 4 was 47.

Next, an adhesive layer 5 made of an acrylic adhesive and having a thickness of 5 μm was formed on one surface of the porous resin layer 4.

Next, a 12.5 μm-thick second metal layer 6 made of copper was adhered to one surface of the adhesive layer 5 in the thickness direction.

Thus, a laminated material 14 including the first metal layer 3, the porous resin layer 4, the adhesive layer 5, and the second metal layer 6 was produced. The thickness T0 of the laminated material 14 was 150 μm.

Separately, two second protection members 7 were prepared. Specifically, each second protection member 7 is made of polyethylene (PE) and has a thickness of 50 μm. The total thickness of the two second protection members 7 is 100 μm. The other surface of the second protective material 7 on the other side had been subjected to an adhesive treatment with an acrylic adhesive. The Shore D hardness H1 of the second protective material 7 was smaller than the Shore D hardness H2 (47) of the porous resin layer 4, specifically, 40.

{Circle around (2)} Then, two second protective members 7 were arranged on one surface in the thickness direction of the second metal layer 6.

Thereby, as shown in FIG. 6, the first metal foil 3, the porous resin layer 4, the adhesive layer 5, the second metal layer 6, and the second protective material 7 are sequentially lowered toward one side in the thickness direction. The dielectric substrate material 1 was manufactured.

Example 2
A low dielectric substrate material 1 was manufactured in the same manner as in Example 1 except that the thickness T1 of the second protective material 7 was changed to 50 μm. Specifically, the number of the second protective members 7 is one.

Example 3
Processing was performed in the same manner as in Example 1 except that the material of the second protective material 7 was changed from polyethylene to polyethylene terephthalate (PET).

In addition, the Shore D hardness H1 of the second protective material 7 was larger than the Shore D hardness H2 of the porous resin layer 4, specifically, 78.

Comparative Example 1
The processing was performed in the same manner as in Example 2 except that the material of the second protective material 7 was changed from polyethylene (PE) to polyethylene terephthalate (PET).

<Manufacture of low dielectric substrate material corresponding to FIG. 6>
Example 4
The layer structure of the low dielectric substrate material 1 is the layer structure of FIG. 3, that is, the low dielectric substrate material 1 having the first protective material 2, the porous resin layer 4, and the second metal layer 6 in this order in the thickness direction. Except having changed to, it carried out similarly to Example 1.

Example 5
The layer structure of the low dielectric substrate material 1 is the layer structure of FIG. 3, that is, the low dielectric substrate material 1 having the first protective material 2, the porous resin layer 4, and the second metal layer 6 in this order in the thickness direction. Except having changed to, it carried out similarly to Example 2.

Example 6
The layer structure of the low dielectric substrate material 1 is the layer structure of FIG. 3, that is, the low dielectric substrate material 1 having the first protective material 2, the porous resin layer 4, and the second metal layer 6 in this order in the thickness direction. Except having changed to, it carried out similarly to Example 3.

Comparative Example 2
The layer structure of the low dielectric substrate material 1 is the layer structure of FIG. 3, that is, the low dielectric substrate material 1 having the first protective material 2, the porous resin layer 4, and the second metal layer 6 in this order in the thickness direction. Except having changed to, it processed similarly to the comparative example 1.

Evaluation The following items were evaluated. The results are shown in Tables 1 and 2.

<Hardness>
The Shore D hardness H1 of the second protective material 7, the Shore D hardness H3 of the first protective material 2, and the Shore D hardness H2 of the porous resin layer 4 are each a Shore D hardness meter (manufactured by Kamishima Seisakusho). Was calculated.

When measuring the Shore D hardness H1 of the second protective material 7, a plurality of the second protective materials 7 are stacked in the thickness direction until a thickness of 3000 μm is obtained, and a laminate is formed. Three equally divided points were measured, and the average value was defined as Shore D hardness H1.

When measuring the Shore D hardness H3 of the first protective material 2, a plurality of first protective materials 2 are stacked in the thickness direction until a thickness of 3000 μm is obtained, and a laminate is formed. Three equally divided points were measured, and the average value was defined as Shore D hardness H1.

In the measurement of the Shore D hardness H2 of the porous resin layer 4, first, only the porous resin layer 4 was taken out of the low dielectric substrate material 1. Specifically, the second metal layer 6, the adhesive layer 5, the first metal layer 3, and the like were peeled off from the laminated material 14 to obtain the porous resin layer 4. A plurality of the porous resin layers 4 are stacked in the thickness direction until a thickness of 3000 μm is formed to form a laminate. D hardness H2.

<Surface protection>
Strain of 10, 15, 20, 30, 40, and 50 μm was applied to one surface in the thickness direction of the low dielectric substrate material 1 using a coolant Bruch micrometer (MDC-25M manufactured by Mitutoyo Corporation). After release, the presence or absence of a dent on one surface was visually confirmed and judged. Out of the plurality of dents described above, the evaluation was performed in order from the smallest dent, and if it was confirmed that dents were present (remaining), evaluation was not performed for dents exceeding that.

The above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be construed as limiting. Modifications of the invention apparent to those skilled in the art are included in the following claims.

This low dielectric substrate material 1 is preferably used for manufacturing a high-frequency antenna or a high-speed transmission substrate conforming to the fifth generation (5G) standard.

REFERENCE SIGNS LIST 1 Low dielectric substrate material 2 First protective material 4 Porous resin sheet 6 Second metal foil 7 Second protective material 14 Laminated material H1 Shore D hardness H2 of second protective material Shore D hardness H3 of porous resin layer First protection Shore D hardness of material T0 Thickness of laminated material T1 Thickness of second protective material

Claims

Comprising a porous resin layer and a metal layer in order in the thickness direction,
Further comprising a protective material disposed on one of the surface of the porous resin layer and the metal layer,
The Shore D hardness H1 at 23 ° C. of the protective material and the Shore D hardness H2 at 23 ° C. of the porous resin layer satisfy the following expression (1), or
A low-dielectric substrate material, wherein a thickness T1 of the protective material and a thickness T0 of a laminate including the porous resin layer and the metal layer satisfy the following expression (2).
H1 <H2 (1)
T1> 0.5 × T0 (2)
低 The low dielectric substrate material according to claim 1, wherein both the formulas (1) and (2) are satisfied.
The low dielectric substrate material according to claim 1, wherein the porosity of the porous resin layer is 60% or more.