JP7222727B2 - Low dielectric substrate material and manufacturing method thereof - Google Patents

Description

The present invention relates to a low dielectric substrate material and its manufacturing method.

In recent years, low-dielectric polymer films are known to be useful as films for millimeter-wave antennas capable of long-distance wireless communication.

For example, a laminate comprising a copper foil and a polyimide porous film formed thereon and having pores having a porosity of 60% or more and an average pore diameter of 50 μm or less has been proposed (for example, the following patent document 1). To manufacture this laminate, a copper foil is provided, a polyimide precursor layer is formed on the copper foil, and then the polyimide precursor layer is foamed and cured to produce a polyimide porous film.

International publication 2018/186486

However, in the circuit forming process of forming a circuit from a copper foil, if the laminate is pressed by a flat plate press, variations in the thickness of the polyimide porous film occur. Therefore, the dielectric constant varies depending on the location in the circuit, resulting in non-uniform characteristic impedance in the circuit. As a result, a part of the signal current flowing in the circuit is reflected and becomes noise, or the output is lowered.

In order to solve the above problems, the present invention provides a low-dielectric substrate material capable of making the thickness of a porous resin layer uniform, and a method of manufacturing the same.

The present invention (1) comprises a metal layer, a porous resin layer arranged on one side in the thickness direction of the metal layer, and a porous resin layer arranged on the one side of the metal layer so as to be adjacent to the porous resin layer. and a spacer layer that is thinner than the porous resin layer.

The low dielectric substrate material comprises a spacer layer that is thinner than the porous resin layer. Therefore, by pressing this low-dielectric substrate material in the thickness direction, the porous resin layer is pressed up to the thickness of the spacer layer, while pressing exceeding the thickness can be suppressed. Therefore, it is possible to prevent the thickness of the porous resin layer from becoming uneven due to excessive pressing. That is, the spacer layer can control the press amount (compression amount) to make the thickness of the porous resin layer uniform.

In the present invention (2), the metal layer is a first margin area and a second margin area respectively arranged at one end and the other end in a first direction included in a plane direction orthogonal to the thickness direction. and includes the first margin area and the second margin area that are included in the plane direction and extend in a second direction orthogonal to the first direction, and the spacer layer has the The low dielectric substrate material according to (1), comprising a first spacer member included in the first margin area and a second spacer member included in the second margin area.

In this low-dielectric substrate material, the spacer includes the first spacer member and the second spacer member arranged at one end and the other end in the first direction, respectively, so that the press amount in the first direction is made uniform. be able to. Therefore, the thickness of the porous resin layer in the first direction can be made uniform.

The present invention (3) includes the low dielectric substrate material according to (2), wherein the first spacer member and the second spacer member have shapes extending in the second direction.

In this low dielectric substrate material, the first spacer member and the second spacer member have shapes extending in the second direction. Therefore, the thickness of the porous resin layer in the second direction can be made uniform.

According to the present invention (4), the first spacer member is arranged at one end and the other end of the first margin area in the second direction, and they are spaced apart in the second direction. , the second spacer member is arranged at each of the second direction one end and the other end of the second margin area, and they are spaced apart in the second direction, according to (2) of low dielectric substrate materials.

In this low-dielectric substrate material, the first spacer members are arranged at one end and the other end of the first margin area in the second direction, and the second spacer members are arranged at one end and the other end of the second margin area in the second direction. located at each of the other ends. Therefore, the press amount in the second direction can be made uniform. Therefore, the thickness of the porous resin layer in the second direction can be made uniform.

The present invention (5) includes the low dielectric substrate material according to any one of (1) to (4), wherein the spacer layer is a non-porous layer.

In this low-dielectric substrate material, the spacer layer is a non-porous layer, so it is harder than the porous resin layer. Therefore, the function of the spacer layer can be fully exhibited.

In the present invention (6), the porous resin layer has a first side surface facing the spacer layer, the spacer layer has a second side surface facing the porous resin layer, and the first side surface faces the porous resin layer. The low dielectric substrate material according to any one of (1) to (5), wherein the side surface and the second side surface are in intimate contact.

Since the first side surface and the second side surface of the low dielectric substrate material are in close contact with each other, it is possible to suppress the displacement of the porous resin layer with respect to the spacer layer when the low dielectric substrate material is pressed. .

The present invention (7) includes the low dielectric substrate material according to any one of (6), wherein the porous resin layer and the spacer layer are made of the same material.

In this low dielectric substrate material, since the porous resin layer and the spacer layer are made of the same material, the adhesion between the first side surface and the second side surface can be improved.

The present invention (8) is a method for manufacturing a low dielectric substrate material according to any one of (1) to (7), wherein a spacer material is applied to the one surface of the metal layer, and the first a first step of forming a coating film; a second step of applying a resin material to the one surface of the metal layer so as to be adjacent to the spacer material to form a second coating film; A third step of foaming the coating film to form a porous coating film, a fourth step of curing the first coating film to form the spacer layer, and curing the porous coating film, and a fifth step of forming the porous resin layer, and a method for manufacturing a low dielectric substrate material.

In this method, the first, second and third steps can be performed in sequence, and the fourth and fifth steps can be performed in sequence. Therefore, in this method, the first step and the fourth step are performed in order, and then the second step, the third step and the fifth step are performed in order, or the second step, the third step and the fifth step are performed. Compared to the method of sequentially performing the first step and the fourth step, it is possible to perform the fourth step and the fifth step with high manufacturing efficiency.

The present invention (9) includes the method of manufacturing a low dielectric substrate material according to (8), wherein the fourth step and the fifth step are performed simultaneously.

In this manufacturing method, since the fourth step and the fifth step are performed simultaneously, a low dielectric substrate material can be manufactured in a short time.

According to the low-dielectric substrate material of the present invention, the amount of press (amount of compression) can be controlled by the spacer layer to make the thickness of the porous resin layer uniform.

According to the method of manufacturing a low-dielectric substrate material of the present invention, the fourth step and the fifth step can be performed with high manufacturing efficiency.

1A and 1B show an embodiment of the low dielectric substrate material of the present invention, FIG. 1A showing a plan view and FIG. 1B showing a cross-sectional view along line XX of FIG. 1A. 2A to 2F are process diagrams for explaining the manufacturing method and processing method of the low dielectric substrate material shown in FIG. 2C is the second step of forming the second coating film, FIG. 2D is the third step of forming the porous coating film, the fourth step of forming the spacer layer, and the porous resin layer FIG. 2E shows the step of pressing the low dielectric substrate material, and FIG. 2F shows the step of obtaining the low dielectric substrate material after pressing. FIG. 3 shows a modification of the low dielectric substrate material shown in FIG. FIG. 10 is a plan view of a modification arranged at one end and the other end of the area in the second direction). FIG. 4 shows a modification of the low dielectric substrate material shown in FIG. FIG. 11 shows a plan view of a modification arranged at the end). FIG. 5 shows a modification of the low dielectric substrate material shown in FIG. FIG. 10 is a plan view of a modified example arranged in the middle part). FIG. 6 shows a plan view of a variant of the low-dielectric substrate material shown in FIG. 1A (a variant in which the spacer layer consists of first spacer members coinciding with the first margin areas). FIG. 7 shows a plan view of a modification of the low dielectric substrate material shown in FIG. 1A (a modification in which the spacer layer is composed of the first spacer member arranged at one end in the first direction of the first margin area). FIG. 8 shows measurement points for the dimensions and thickness of the low dielectric substrate material of Example 1. FIG. FIG. 9 shows measurement points for the dimensions and thickness of the low dielectric substrate material of Comparative Example 1. FIG.

<One embodiment>
One embodiment of the low dielectric substrate material of the present invention is described with reference to FIGS. 1A-1B.

The low dielectric substrate material 1 has one surface and the other surface facing each other in the thickness direction, and has a sheet shape extending in a plane direction orthogonal to the thickness direction. A low dielectric substrate material 1 includes a metal layer 2 , a porous resin layer 3 and a spacer layer 4 . Preferably, the low dielectric substrate material 1 comprises only the metal layer 2, the porous resin layer 3 and the spacer layer 4.

The metal layer 2 has the same outer shape as the low dielectric substrate material 1 . Specifically, the metal layer 2 has one surface and the other surface facing each other in the thickness direction, and has a sheet shape extending in the surface direction. One surface in the thickness direction of the metal layer 2 is a flat surface. In addition, the metal layer 2 forms the other side in the thickness direction of the low dielectric substrate material 1 .

More specifically, the metal layer 2 has a substantially rectangular sheet shape, and is arranged at each of one end and the other end in a first direction (direction corresponding to the left-right direction in FIG. 1A) included in the surface direction. It has a first margin area 5 and a second margin area 6 which are aligned.

The first margin area 5 and the second margin area 6 are areas where the porous resin layer 3 described below is not arranged. The first margin area 5 and the second margin area 6 are spaced apart from each other in the first direction. Each of the first margin area 5 and the second margin area 6 is a substantially band-shaped area extending in a second direction (corresponding to the vertical direction in FIG. 1A) orthogonal to the first direction.

The material of the metal layer 2 is not particularly limited, and examples thereof include metals such as copper, iron, silver, gold, aluminum, nickel, and alloys thereof (stainless steel, bronze). Copper is preferred.

The thickness of the metal layer 2 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.

The porous resin layer 3 is arranged on one side of the metal layer 2 . Specifically, the porous resin layer 3 is arranged between the first margin area 5 and the second margin area 6 on one side of the metal layer 2 . The porous resin layer 3 forms one surface of the low dielectric substrate material 1 together with the spacer layer 4 described below.

The porous resin layer 3 has one side and the other side facing each other in the thickness direction, and has a sheet shape extending between a first margin area 5 and a second margin area 6 on one side of the metal layer 2 . In addition, the porous resin layer 3 has a first outer surface 9 as an example of a first side surface that connects one edge in the first direction on one surface and one edge in the first direction on the other surface, and A second outer surface 10 as an example of a first side surface connecting the edge and the other edge in the first direction of the other surface. Thereby, the thickness direction one surface, the other surface, the first outer surface 9 and the second outer surface 10 define a substantially rectangular shape. That is, the porous resin layer 3 has a substantially rectangular shape in a cross section along the first direction.

The porous resin layer 3 is not particularly limited, and examples thereof include porous films (preferably polyimide porous films) described in International Publication No. 2018/186486.

Moreover, the porous resin layer 3 has a large number of fine pores (pores). The porous resin layer 3 mainly has, for example, a closed cell structure.

The porosity of the porous resin layer 3 is, for example, 60% or more, preferably 70% or more, more preferably 80% or more, and is, for example, less than 100%.

The average diameter (that is, the average pore diameter) of the pores 10 in the porous resin layer 3 is, for example, 10 μm or less and, for example, 0.1 μm or more.

The material (an example of the resin material) of the porous resin layer 3 is not particularly limited, and examples thereof include resins such as thermosetting resins and thermoplastic resins. Thermosetting resins are preferred.

Examples of thermosetting resins include polycarbonate resins, thermosetting polyimide resins, thermosetting fluorinated polyimide resins, epoxy resins, phenol resins, urea resins, melamine resins, diallyl phthalate resins, silicone resins, and thermosetting urethane resins. , fluororesins (polymers of fluorine-containing olefins (specifically, polytetrafluoroethylene (PTFE), etc.)), liquid crystal polymers (LCP), and the like. These can be used singly or in combination of two or more. Thermosetting polyimide resins are preferred.

The dielectric constant of the porous resin layer 3 at a frequency of 10 GHz is, for example, 3.0 or less, preferably 2.5 or less, more preferably 2.0 or less.

The thickness of the porous resin layer 3 is, for example, 2 µm or more, preferably 5 µm or more, more preferably 25 µm or more, still more preferably 50 µm or more, and particularly preferably 75 µm or more. Below, it is preferably 500 μm or less, preferably 250 μm. The thickness of the porous resin layer 3 is the distance between one surface of the porous resin layer 3 in the thickness direction and one surface of the metal layer 2 in the thickness direction. Moreover, the thickness of the porous resin layer 3 is the average thickness in the surface direction.

The thickness ratio of the porous resin layer 3 is, for example, 1 μm or more, preferably 5 μm or more, and is, for example, 100 μm or less, more preferably 50 μm or less, more preferably 20 μm or less.

The ratio of the thickness of the porous resin layer 3 to the thickness of the metal layer 2 is, for example, 2 or more, preferably 5 or more, and is, for example, 100 or less, more preferably 50 or less.

The spacer layer 4 is a layer extending in the plane direction so as to control the pressing of the porous resin layer 3 in the later-described pressing (see FIG. 2E).

The spacer layer 4 forms one surface in the thickness direction of the low dielectric substrate material 1 together with the porous resin layer 3 described above. The spacer layer 4 has one smooth surface and the other smooth surface facing each other in the thickness direction. One surface of the spacer layer 4 is exposed on one side in the thickness direction. The other side of spacer layer 4 is in contact with one side of metal layer 2 .

A spacer layer 4 is arranged on one side of the metal layer 2 . Specifically, the spacer layer 4 is arranged adjacent to the porous resin layer 3 in the first direction on one side of the metal layer 2 . Specifically, the spacer layer 4 and the porous resin layer 3 are arranged without a gap in the first direction.

Specifically, the spacer layer 4 is arranged in a first margin area 5 and a second margin area 6 on one side of the metal layer 2 . The spacer layer 4 includes a first spacer member 7 included in the first margin area 5 and a second spacer member 8 included in the second margin area 6 when projected in the thickness direction.

The first spacer member 7 has a substantially rectangular shape extending in the first direction. The first spacer member 7 overlaps the first margin area 5 when projected in the thickness direction. That is, the entire other surface of the first spacer member 7 is in contact with the entire surface of the first margin area 5 . That is, the first spacer member 7 matches the first margin area 5 in plan view. Specifically, each of the first direction one edge, the first direction other edge, the second direction one edge, and the second direction other edge of the first spacer member 7 is the first direction edge of the first margin area 5, It coincides with each of the first direction other edge, the second direction one edge, and the second direction other edge. The first spacer member 7 has a substantially rectangular shape in a cross-sectional view along the first direction, and has a first surface as an example of a second side surface connecting one surface, the other surface, and the other edge in the first direction. It integrally has an inner surface 11 . The first inner surface 11 faces the first outer surface 9 of the porous resin layer 3 . The first inner surface 11 contacts the first outer surface 9 .

The second spacer member 8 has a substantially rectangular shape extending in the first direction. The second spacer member 8 overlaps the second margin area 6 when projected in the thickness direction. That is, the entire other surface of the second spacer member 8 is in contact with the entire surface of the second margin area 6 . That is, the second spacer member 8 matches the second margin area 6 in plan view. Specifically, each of the first direction edge, the first direction other edge, the second direction edge, and the second direction other edge of the second spacer member 8 is the first direction edge of the second margin area 6, It coincides with each of the first direction other edge, the second direction one edge, and the second direction other edge. The second spacer member 8 has a substantially rectangular shape in a cross-sectional view along the first direction, and has one surface, the other surface, and a second inner surface as an example of a second side surface connecting one end edge in the first direction. It has side surfaces 12 integrally. The second inner surface 12 faces the second outer surface 10 of the porous resin layer 3 . The second inner surface 12 contacts the second outer surface 10 .

The spacer layer 4 is not particularly limited as long as the pressing of the porous resin layer 3 can be controlled, and is preferably a non-porous layer. That is, unlike the porous resin layer 3, the spacer layer 4 preferably does not have fine pores (pores) and is formed as a solid dense layer.

Examples of the material of the spacer layer 4 (an example of the spacer material) include resins such as the above-described thermosetting resins and thermoplastic resins. Further, as the material of the spacer layer 4, the metals exemplified for the metal layer 2 can be used. A material for the spacer layer 4 is preferably a resin, more preferably a thermosetting resin, and still more preferably a thermosetting polyimide resin.

The material of the spacer layer 4 is preferably the same resin as the resin exemplified for the porous resin layer 3, more preferably the same thermosetting resin as the thermosetting resin exemplified for the porous resin layer 3. More preferably, the same material as that of the porous resin layer 3 is used.

The spacer layer 4 is thinner than the porous resin layer 3 . That is, the thickness of the spacer layer 4 is less than the thickness of the porous resin layer 3 .

The value obtained by subtracting the thickness of the spacer layer 4 from the thickness of the porous resin layer 3 is, for example, greater than 0 μm, preferably 1 μm or more, more preferably 2 μm or more, further preferably 5 μm or more. It is 50 μm or less, preferably 25 μm or less.

The thickness of the spacer layer 4 is the distance between one surface of the spacer layer 4 in the thickness direction and one surface of the metal layer 2 in the thickness direction.

The ratio of the thickness of the spacer layer 4 to the thickness of the porous resin layer 3 is, for example, less than 1, preferably 0.99 or less, more preferably 0.95 or less, or, for example, 0.5 or more. , preferably 0.6 or more, more preferably 0.7 or more, and still more preferably 0.8 or more.

The thickness of the spacer layer 4 is, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and is, for example, 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less.

The thickness of the spacer layer 4 is substantially uniform in the planar direction, that is, the spacer layer 4 has the same thickness in the planar direction.

In addition, since the first spacer member 7 is thinner than the porous resin layer 3, the first spacer member 7 exposes the one side portion in the thickness direction of the first outer surface 9 of the porous resin layer 3 to the one side in the first direction. are doing. Also, the first inner side surface 11 of the first spacer member 7 is in close contact with the other side portion in the thickness direction of the first outer side surface 9 of the porous resin layer 3 .

Since the second spacer member 8 is thinner than the porous resin layer 3 , the second spacer member 8 exposes one thickness direction portion of the second outer surface 10 side to the other side in the first direction. In addition, the second inner side surface 12 of the second spacer member 8 is in close contact with the other side portion in the thickness direction of the second outer side surface 10 of the porous resin layer 3 .

Each of the first spacer member 7 and the second spacer member 8 has a first direction length of, for example, 0.1 cm or more, preferably 0.5 cm or more, and for example, 5 cm or less, preferably 2 cm or less. is.

The ratio of the first direction length of each of the first spacer member 7 and the second spacer member 8 to the first direction length of the metal layer 2 is, for example, 0.01 or more, preferably 0.02 or more, or more. It is preferably 0.05 or more and, for example, 0.2 or less, preferably 0.1 or less.

The thickness of the low dielectric substrate material 1 is the total thickness of the metal layer 2 and the porous resin layer 3, and is, for example, 10 μm or more, preferably 15 μm or more, more preferably 30 μm or more. ,000 μm or less, preferably 600 μm or less, preferably 300 μm.

The ratio of the thickness of the metal layer 2 to the thickness of the low dielectric substrate material 1 is, for example, 0.01 or more, preferably 0.05 or more, and for example, 0.75 or less, preferably 0.25 or less. is.

The ratio of the thickness of the porous resin layer 3 to the thickness of the low dielectric substrate material 1 is, for example, 0.99 or less, preferably 0.95 or less, and for example, 0.25 or more, preferably 0.95 or less. 75 or more.

Next, the manufacturing method and processing method of the low dielectric substrate material 1 will be described with reference to FIGS. 2A to 2F.

In the production of the low dielectric substrate material 1 in one embodiment (FIGS. 2A to 2D), for example, each member is moved, for example, in the second direction (paper thickness direction in FIGS. 2A to 2D) by a roll-to-roll method. Form while conveying to.

As shown in FIG. 2A, first, a metal layer 2 is provided.

As shown in FIG. 2B, a spacer material (preferably resin) is then placed in the first margin area 5 and the second margin area 6 on one side of the metal layer 2 (performing the first step). Preferably, a first varnish containing a resin and a solvent is prepared, the first varnish is applied (printed) to the first margin area 5 and the second margin area 6 of the metal layer 2 at the same time, and then dried at the same time to remove the solvent. is removed to form the first coating film 13 .

When the resin is a thermosetting resin, a first varnish containing the precursor resin is prepared, the first varnish is applied to the first margin area 5 and the second margin area 6 of the metal layer 2, and then and drying to remove the solvent to form the first coating 13 made of the precursor resin. In this case, the first coating film 13 is still in an uncured state.

The solvent is not particularly limited, and examples thereof include organic solvents such as N-methyl-2-pyrrolidone (NMP). The solid content concentration in the first varnish is adjusted to, for example, 10% by mass or more and 50% by mass or less. The method of applying the first varnish is not particularly limited, and for example, an applicator capable of relatively moving (applying) in the second direction with respect to the metal layer 2 is used.

The first coating 13 is made of spacer material and has substantially the same shape and dimensions as the spacer layer 4 .

As shown in FIG. 2C, a resin material is then placed between the first margin area 5 and the second margin area 6 on one side of the first metal layer 3 (implementation of the second step). The resin material contains the resin described above (preferably the same resin as the spacer layer 4), a porosity agent, and a nucleating agent, and a second varnish containing this resin material and solvent is prepared. Next, a second varnish is applied (printed) on one side of the first metal layer 3 between the first margin area 5 and the second margin area 6, and then dried to remove the solvent to form a second coating film. 14 is formed.

The method for forming the second coating film 14 and the like can conform to the description in International Publication No. 2018/186486.

The second coating film 14 is made of a resin material (expandable composition containing a resin and a nucleating agent) and has the same planar shape as the porous resin layer 3 .

The second coating film 14 is, for example, thinner than the first coating film 13. Specifically, the other surface of the second coating film 14 is in contact with one surface of the metal layer 2, while the second coating film 14 is One surface of the film 14 is arranged on the other side in the thickness direction from the one surface in the thickness direction of the first coating film 13 when projected in the first direction. Specifically, the entire surface of the first outer surface 9 of the second coating 14 is in contact with the other thickness direction portion of the first inner surface 11 of the first coating 13 corresponding to the first spacer member 7 . . The entire surface of the second outer surface 10 of the second coating 14 is in contact with the other portion in the thickness direction of the second inner surface 12 of the first coating 13 corresponding to the second spacer member 8 .

The second coating film 14 is closely adjacent to the first coating film 13 in the first direction.

Thereafter, as shown in FIG. 2D, the second coating film 14 is foamed to form a porous coating film 19 (implementation of the third step).

A method for foaming the second coating film 14 is not particularly limited, and examples thereof include a physical foaming method and a chemical foaming method. Physical foaming methods include, for example, a method of dispersing a porosity agent and a nucleating agent in a resin and extracting the porosity agent using a supercritical fluid to form bubbles (supercritical extraction method); A method of dispersing a boiling point liquid (foaming agent) in a resin and then volatilizing the foaming agent to form bubbles (low boiling point liquid volatilization method) can be used. Note that the supercritical extraction method is described in detail in, for example, International Publication No. 2018/186486.

As the chemical foaming method, for example, a method of forming bubbles by gas generated by thermal decomposition of a compound added to the resin can be used.

When the resin material contains a thermosetting resin, the porous coating film 19 is preferably in a state before being completely cured.

After that, when the first coating film 13 and the porous coating film 19 contain a thermosetting resin, the first coating film 13 and the porous coating film 19 are respectively cured to form the spacer layer 4 and the porous resin layer. 3 are respectively formed (implementation of the fifth step).

Specifically, the first coating film 13 and the porous coating film 19 are heated simultaneously.

Thereby, the first coating film 13 containing the thermosetting resin is thermoset.

On the other hand, the porous coating film 19 containing thermosetting resin is thermoset.

Thereby, the spacer layer 4 and the porous resin layer 3 are formed. The porous resin layer 3 is formed with its first outer surface 9 and second outer surface 10 in close contact with the first inner surface 11 and second inner surface 11 of the spacer layer 4, respectively.

Thus, a low dielectric substrate material 1 including the metal layer 2, the porous resin layer 3 and the spacer layer 4 is obtained.

After that, one side of the porous resin layer 3 in the thickness direction is pressed to make the thickness uniform. For this processing, for example, a batch method is adopted.

As shown in FIG. 2E, for example, a plate press 15 having an upper plate 16 and a lower plate 17 is used to press the porous resin layer 3 . The plate press 15 can also be equipped with a heat source (not shown). The other surface in the thickness direction of the upper plate 16 is a flat surface. One surface in the thickness direction of the lower plate 17 is a flat surface. The other surface of the upper plate 16 and one surface of the lower plate 17 are substantially parallel. Specifically, the upper plate 16 and the lower plate 17 can relatively move in the thickness direction while the other surface of the upper plate 16 and the one surface of the lower plate 17 are kept substantially parallel.

First, the low-dielectric substrate material 1 is placed on the flat press machine 15 . Specifically, the other thickness direction surface of the metal layer 2 is brought into contact with the one thickness direction surface of the lower plate 17 .

As shown in FIG. 2E, the top plate 16 is then pressed against the low dielectric substrate material 1 in the thickness direction. Specifically, the upper plate 16 is moved to the other thickness direction side while bringing the other thickness direction surface of the upper plate 16 into contact with the one thickness direction surface of the low dielectric substrate material 1 .

As a result, first, one surface in the thickness direction of the porous resin layer 3 moves toward the other side in the thickness direction. That is, the porous resin layer 3 is pressed in the thickness direction.

Subsequently, when the other thickness direction surface of the upper plate 16 contacts the one thickness direction surface of the spacer layer 4 , the movement of the other thickness direction surface of the upper plate 16 to the other thickness direction side is restricted, and the porous resin layer 3 press does not progress any further.

That is, the pressing in the thickness direction of the porous resin layer 3 is carried out so that the upper plate 16 of the plate press 15 is in contact with the spacer layer 4 . Specifically, the porous resin layer 3 is pressed by a value obtained by subtracting the thickness of the spacer layer 4 from the thickness of the porous resin layer 3 before pressing.

Subsequently, the upper plate 16 is kept in contact with the spacer layer 4 for, for example, 1 minute or more, preferably 5 minutes or more, more preferably 15 minutes or more, and for example, 60 minutes or less. In other words, the pressing of the porous resin layer 3 is carried out for the time described above.

In addition to the pressing, the low dielectric substrate material 1 can be heated. The heating temperature is, for example, 100° C. or higher, preferably 150° C. or higher, and is, for example, 210° C. or lower, preferably 195° C. or lower.

After that, as shown in FIG. 2F, the press by the flat press machine 15 is released.

This allows the porous resin layer 3 to restore its thickness. In other words, one surface of the porous resin layer 3 in the thickness direction is allowed to be arranged above the one surface of the spacer layer 4 in the thickness direction.

The thickness of the porous resin layer 3 after pressing becomes uniform in the surface direction.

The ratio of the thickness of the porous resin layer 3 after pressing to the thickness of the porous resin layer 3 before pressing is, for example, less than 1, further 0.99 or less, and for example, 0.5 or more, Furthermore, it is 0.8 or more.

After that, if necessary, if the low dielectric substrate material 1 is manufactured by the roll-to-roll method, the low dielectric substrate material 1 is cut along the first direction.

This low dielectric substrate material 1 is provided with a spacer layer 4 thinner than the porous resin layer 3 . Therefore, in order to make the thickness of the porous resin layer 3 uniform, if the low dielectric substrate material 1 is pressed in the thickness direction as shown in FIG. While being pressed, it is possible to suppress the pressing beyond. Therefore, it is possible to prevent the thickness of the porous resin layer 3 from becoming uneven due to excessive pressing. That is, the thickness of the porous resin layer 3 can be made uniform by controlling the press amount (compression amount) by the spacer layer 4 .

In the low-dielectric substrate material 1, the spacer layer 4 faces in the first direction the first spacer member 7 and the second spacer member 8 arranged at one end and the other end in the first direction, respectively. , the press amount in the first direction can be made uniform. Therefore, the thickness of the porous resin layer 3 in the first direction can be made uniform.

Furthermore, in this low dielectric substrate material 1, the first spacer member 7 and the second spacer member 8 have shapes extending in the second direction. Therefore, the press amount in the second direction can be made uniform. Therefore, the thickness of the porous resin layer 3 in the second direction can be made uniform.

Further, in the low dielectric substrate material 1, the spacer layer 4 is harder than the porous resin layer 3 if it is a non-porous layer. Therefore, the function of the spacer layer 4 and uniform pressing of the porous resin layer 3 can be fully exhibited.

Further, in this low dielectric substrate material 1, since the first outer surface 9 and the first inner surface 11 are in close contact, and the second outer surface 10 and the second inner surface 12 are in close contact, the low dielectric substrate material 1 is pressed. It is possible to prevent the porous resin layer 3 from being displaced with respect to the spacer layer 4 at the time.

Moreover, in the low dielectric substrate material 1, if the porous resin layer 3 and the spacer layer 4 are made of the same material, the adhesion between the first outer surface 9 and the first inner surface 11 and the second outer surface 10 and The adhesion force of the second inner surface 12 can be improved.

Modifications In each modification below, the same reference numerals are given to the same members and steps as in the above-described embodiment, and detailed description thereof will be omitted. Moreover, each modification can have the same effects as the one embodiment, unless otherwise specified. Furthermore, one embodiment and its modifications can be combined as appropriate.

In a modified example, although not shown, the first step and the fourth step can be performed in order, and then the second step, the third step and the fifth step can be performed in order. That is, first, the spacer material is placed on the metal layer 2 to form the first coating 13, and then, when the first coating 13 contains a thermosetting resin, the first coating 13 is formed. is heated to form the spacer layer 4 (implementation of the first and fourth steps). After that, a resin material is placed on the metal layer 2 to form the second coating 14 , and then the second coating 14 is foamed to form the porous coating 19 . Next, when the porous coating film 19 contains a thermosetting resin, the porous coating film 19 is heated to form the porous resin layer 3 (implementation of the second, third and fifth steps ). Conversely, the 2nd, 3rd and 5th steps can be performed in sequence, and then the 1st and 4th steps can be performed in sequence.

Preferably, as in one embodiment, the first, second and third steps are performed in sequence, and then the fourth and fifth steps are performed in sequence. According to such an embodiment, the fourth step and the fifth step can be efficiently performed by heating, and can be performed at the same time, as compared with the method of the modified example described above.

Furthermore, in one embodiment, since the fourth step and the fifth step are performed simultaneously, the low dielectric substrate material 1 can be manufactured in a short time.

A roll press (not shown), for example, can be used instead of the flat plate press 15 for the press shown in FIG. 2E. If the roll press machine is used, the porous resin layer 3 can be pressed by the roll-to-roll method, and therefore the manufacturing efficiency is excellent.

Moreover, the transport direction in the roll-to-roll method is not particularly limited, and for example, the metal layer 2 can be transported along the first direction.

Preferably, the metal layer 2 is transported along the second direction. When conveying the metal layer 2 along the second direction, each of the first coating film 13 and the second coating film 14 extending along the second direction can be easily applied by an applicator.

In the first step, the spacer material is applied (printed) in a pattern corresponding to the first margin area 5 and the second margin area 6 of the metal layer 2 to form the first coating 13 having the same pattern. However, for example, by including a photosensitive component in the spacer material, the photosensitive spacer material is first applied to the entire surface of one surface in the thickness direction of the metal layer 2, and then exposed and developed to form the first margin area. It is also possible to pattern the first coating 13 with a pattern corresponding to 5 and the second margin area 6 .

In one embodiment, the first inner surface 11 is in intimate contact with the first outer surface 9 of the porous resin layer 3, although a gap may be provided between them, for example. The second inner surface 12 is in close contact with the second outer surface 10 of the porous resin layer 3, but, for example, a gap may be provided between them.

In one embodiment, steps 4 and 5 are performed simultaneously, but they can also be performed separately.

Each of the first spacer member 7 and the second spacer member 8 has a substantially rectangular shape in plan view, but the shape is not particularly limited, and may be, for example, a circular shape in plan view, an oval shape in plan view, or the like.

In another modified example, as shown in FIG. 3, the first spacer members 7 are arranged at one end and the other end of the first margin area 5 in the second direction, respectively. spaced apart in the direction. A second direction intermediate portion of the first margin area 5 is exposed from between the two first spacer members 7 .

The second spacer member 8 is arranged at each of one end and the other end in the second direction of the second margin area 6, and they are spaced apart in the second direction. A second direction intermediate portion of the second margin area 6 is exposed from between the two second spacer members 8 .

The second spacer member 8 arranged at one end in the second direction of the second margin area 6 and the first spacer member 7 arranged at one end in the second direction of the first margin area 5 are arranged in the second direction in plan view. It sandwiches the porous resin layer 3 in one direction. The second spacer member 8 arranged at the other end in the second direction of the second margin area 6 and the first spacer member 7 arranged at the other end in the second direction of the first margin area 5 are, in plan view, , sandwich the porous resin layer 3 in the first direction.

In this low dielectric substrate material 1, the first spacer member 5 is arranged at each of one end and the other end in the second direction of the first margin area 7, and the second spacer member 6 is arranged at the second end of the second margin area 8. It is arranged at each of the two-direction one end and the other end. Therefore, when the porous resin layer 3 is pressed, the press amount in the second direction can be made uniform. Therefore, the thickness of the porous resin layer 3 in the second direction can be made uniform.

Further, as shown in FIG. 4, the first spacer member 7 is arranged at one end of the first margin area 5 in the second direction, while the second spacer member 8 is arranged at the other end of the second margin area 6 in the second direction. It may be arranged at the end. The first spacer member 7 and the second spacer member 8 sandwich the porous resin layer 3 in a direction inclined in the first direction in plan view.

In FIG. 5 , the first spacer member 7 is arranged in the second direction intermediate portion (preferably, the central portion) of the first margin area 5 , while the second spacer member 8 is arranged in the second direction of the second margin area 6 . It is arranged in the direction intermediate part (preferably the central part). The first spacer member 7 and the second spacer member 8 sandwich the porous resin layer 3 in the first direction in plan view.

Moreover, as shown in FIGS. 6 and 7, the spacer layer 4 can be arranged only in the first margin area 5. FIG. Specifically, the spacer layer 4 consists of only the first spacer member 7 .

In the modification of FIG. 6, the first spacer member 7 overlaps the first margin area 5 when projected in the thickness direction.

In the modified example of FIG. 7, the first spacer member 7 is arranged at one end of the first margin area 5 in the second direction.

Preferably, the spacer layer 4 is placed in both the first margin area 5 and the second margin area 6 as shown in FIGS. 1 and 3-5. According to the embodiment shown in FIG. 1 and the modifications shown in FIGS. 3 to 5, the thickness of the porous resin layer 3 after pressing in the first direction can be made uniform.

Moreover, although not shown, the spacer layer 4 can be arranged in a substantially L-shape in plan view on one side in the thickness direction of the metal layer 2 .

Also, although not shown, the spacer layer 4 may be arranged in the middle portion of the metal layer 2 in the first direction, and the porous resin layers 3 may be arranged on both outer sides thereof in the first direction.

In one embodiment, the pressed low-dielectric substrate material 1 is cut along the first direction, but for example, the low-dielectric substrate material 1 before pressed can also be cut along the first direction. .

In the second step, as shown in FIG. 2C, the second coating film 14 is formed thinner than the first coating film 13, but it can also be formed to have the same thickness as the first coating film 13, for example. .

EXAMPLES Examples and comparative examples are shown below to describe the present invention more specifically. In addition, the present invention is not limited to Examples and Comparative Examples. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( content ratio), physical properties, parameters, etc. can.

Example 1
A low dielectric substrate material 1 shown in FIG. 1 and having dimensions shown in FIG. 8 was manufactured.

Specifically, as shown in FIG. 2A, first, a metal layer 2 made of copper and having a length of 14 cm in the first direction, a length of 12 cm in the second direction, and a thickness of 12 μm was prepared.

Subsequently, the polyimide precursor ([BPDA/PDA, DPE]) (P-phenylenediamine/diaminodiphenyl ether, biphenyltetracarboxylic acid dihydrate) and NMP described in the reference example of WO 2018/186486 are included. A first varnish (solid content concentration 20% by mass) is prepared, and then, as shown in FIG. First direction length) of 1 cm was applied at the same time, and then dried at the same time to form a first coating film 13 made of a thermosetting polyimide precursor having a thickness of 125 μm (implementation of the first step).

Next, a second varnish (solid content concentration 20% by mass) described in Example 1 of WO 2018/186486 is prepared, and as shown in FIG. It was applied to one surface of the intervening metal layer 2 and then dried to form a second coating 14 made of a thermosetting polyimide precursor having a thickness of 10 μm (implementation of the second step).

Subsequently, a porosifying agent was extracted from the second coating film 14 using supercritical carbon dioxide, and the second coating film 14 was foamed to form a porous coating film 19 (supercritical extraction method) (third execution of the process).

After that, the first coating film 13 and the porous coating film 19 were simultaneously heated at 380° C. for 2 hours under vacuum. Thereby, as shown in FIG. 2D, the first coating film 13 and the porous coating film 19 were each cured to form the spacer layer 4 and the porous resin layer 3 (implementation of the fourth step and the fifth step). ).

The porous resin layer 3 was thicker than the spacer layer 4 and had an average thickness of 140 μm.

Thus, a low dielectric substrate material 1 including the metal layer 2, the porous resin layer 3 and the spacer layer 4 was manufactured.

Thereafter, as shown in FIG. 2E, the flat plate press 15 pressed the low dielectric substrate material 1 in the thickness direction. The pressing pressure was 5 MPa, the pressing temperature was 180° C., and the pressing time was 30 minutes.

After that, as shown in FIG. 2F, the low-dielectric substrate material 1 was taken out from the flat press machine 15 .

After that, the thickness of the porous resin layer 3 at measurement points A to R shown in FIG. 8 was obtained using a thickness meter. Then, their standard deviations were calculated. The standard deviation indicates the degree of variation in the surface direction of the porous resin layer 3, and a low standard deviation value indicates that the thickness is uniform. Those results are shown in Table 1.

Comparative example 1
A low dielectric substrate material 1 without the spacer layer 4 shown in FIG.

After pressing, the thickness of the porous resin layer 3 at points A to R shown in FIG. 9 was determined using a thickness meter. Their standard deviations were then calculated. Those results are shown in Table 2.

1 Low dielectric substrate material 2 Metal layer 3 Porous resin layer 4 Spacer layer 5 First margin area 6 Second margin area 7 First spacer member 8 Second spacer member 9 First outer surface (an example of the first side surface)
10 Second outer surface (an example of the first side surface)
11 First inner side (an example of a second side)
12 Second inner side (an example of the second side)
13 First coating film 14 Second coating film 19 Porous coating film

Claims (9)

a metal layer;
a porous resin layer disposed on one side in the thickness direction of the metal layer;
a spacer layer disposed adjacent to the porous resin layer on the one surface of the metal layer and having a thickness thinner than the porous resin layer ;
A low dielectric substrate material , wherein the side surface of the spacer layer and the side surface of the porous resin layer are adjacent to each other in a plane direction perpendicular to the thickness direction . The metal layer has a first margin area and a second margin area arranged at one end and the other end, respectively, in a first direction included in a plane direction orthogonal to the thickness direction. having the first margin area and the second margin area extending in a second direction orthogonal to the first direction;
When the spacer layer is projected in the thickness direction,
a first spacer member included in the first margin area;
2. The low dielectric substrate material according to claim 1, further comprising a second spacer member included in said second margin area. 3. The low dielectric substrate material according to claim 2, wherein said first spacer member and said second spacer member have shapes extending in said second direction. the first spacer members are arranged at one end and the other end of the first margin area in the second direction, respectively, and are spaced apart in the second direction;
The second spacer member is arranged at one end and the other end of the second margin area in the second direction, respectively, and they are spaced apart in the second direction. 3. A low dielectric substrate material according to item 2. The low dielectric substrate material according to any one of claims 1 to 4, characterized in that said spacer layer is a non-porous layer. The porous resin layer has a first side facing the spacer layer,
The spacer layer has a second side facing the porous resin layer,
6. The low dielectric substrate material according to claim 1, wherein said first side surface and said second side surface are in close contact with each other. 7. The low dielectric substrate material according to claim 6, wherein said porous resin layer and said spacer layer are made of the same material. A method for producing a low dielectric substrate material according to any one of claims 1 to 7,
a first step of applying a spacer material to the one surface of the metal layer to form a first coating;
a second step of applying a resin material to the one surface of the metal layer so as to be adjacent to the spacer material to form a second coating;
a third step of foaming the second coating to form a porous coating;
a fourth step of curing the first coating to form the spacer layer;
and a fifth step of curing the porous coating film to form the porous resin layer. 9. The method of manufacturing a low dielectric substrate material according to claim 8, wherein said fourth step and said fifth step are performed simultaneously.

Images