JP7617563B2 - Resin films, copper-clad laminates, and circuit boards - Google Patents

Description

The present invention relates to a resin film, a copper-clad laminate, and a circuit board that can improve dimensional stability and reduce the dimensional shrinkage rate after etching.

In recent years, polyarylene ether ketone (PAEK) resin, a super engineering plastic, has been attracting attention. This polyarylene ether ketone resin is a thermoplastic crystalline resin that has excellent electrical insulation, heat resistance, chemical resistance, and the like. In view of these excellent properties, polyarylene ether ketone resin is used in the automotive, energy, and medical fields, and is also used in the manufacture of circuit boards such as flexible printed circuit boards (FPCs) (see Patent Documents 1 and 2).

In the case of manufacturing a circuit board using such polyarylene ether ketone resin, although not shown in the figure, a polyarylene ether ketone resin film is formed and prepared as a base substrate, copper foil that will become the circuit pattern is directly bonded to this polyarylene ether ketone resin film, and a photoresist layer for etching is laminated onto the exposed surface. Processing holes are drilled at predetermined locations of this laminated intermediate body, and the photoresist layer is exposed to ultraviolet light and developed to dissolve the photoresist layer in the unexposed areas, revealing the circuit pattern.

When molding a polyarylene ether ketone resin film, in addition to the polyarylene ether ketone resin, fluororesin, talc, mica, etc. are added to the molding material as necessary (see Patent Document 3).

Next, the circuit pattern on the intermediate is etched to remove the photoresist layer, the intermediate is washed and dried, a cover film is attached to most of the intermediate to form an insulating layer, and exposed terminal parts and the like are subjected to surface treatment such as plating. Once the intermediate has been subjected to surface treatment such as plating in this way, the intermediate is machined, the continuity of the circuit pattern is electrically checked, and a final inspection is carried out, and the circuit board can be manufactured.

JP 2021-042294 A JP 2007-051256 A JP 2016-029164 A

Conventional circuit boards are manufactured as described above, and although the use of polyarylene ether ketone resin film can provide excellent electrical insulation, heat resistance, and chemical resistance, there is a problem in that it is not easy to simultaneously improve the adhesion of the polyarylene ether ketone resin film and reduce the dimensional shrinkage rate of the polyarylene ether ketone resin film after etching. If talc is added to the molding material of the polyarylene ether ketone resin film to solve this problem, it will result in a deterioration of adhesion, even though it is possible to reduce the dimensional shrinkage rate of the polyarylene ether ketone resin film after etching of the intermediate.

The present invention has been made in consideration of the above, and aims to provide a resin film, a copper-clad laminate, and a circuit board that can improve adhesion and reduce dimensional shrinkage.

In order to solve the above problems, the present invention provides a molding material containing at least a polyarylene ether ketone resin and synthetic mica, in which the amount of particles having a particle size of 1 μm or less among all the particles of the synthetic mica is 20% or less ,
The ratio of potassium to silicon as measured by electron probe microanalyzer is:
Potassium/silicon = 0.16 to 0.26
It is characterized in that the range is

In addition, the ratio of potassium to silicon measured by an electron probe microanalyzer is
Potassium/silicon = 0.21 to 0.26
It is preferable that the range is 100%.
The molding material preferably contains at least 100 parts by mass of polyarylene ether ketone resin and 20 parts by mass or more and 80 parts by mass or less of synthetic mica.
It is also preferable that the synthetic mica is a non-expanding synthetic mica.

In addition, the D95 value of the synthetic mica can be set to 35 μm or less.
Moreover, the specific surface area of the synthetic mica can be set to 3.0 m ² /g or more.

In order to solve the above-mentioned problems, the present invention is characterized in that it is a copper-clad laminate in which copper foil is laminated and attached to at least one of both sides of a resin film described in any one of claims 1 to 6.

In order to solve the above-mentioned problems, the present invention is characterized in that it is a circuit board having a resin film as defined in any one of claims 1 to 6 .

The resin film in the claims can be manufactured to a thickness of 2 μm or more and 1000 μm or less by known manufacturing methods such as melt extrusion molding, calendar molding, or casting. When manufacturing a resin film by melt extrusion molding, the resin film can be manufactured by melt-kneading the molding material using an extrusion molding machine, extruding the resin film from the die of the extrusion molding machine, and cooling it. In addition, the circuit board includes at least a printed wiring board, a flexible board, a high-frequency circuit board, etc.

According to the present invention, the ratio of potassium to silicon in the synthetic mica contained in the resin film is in the range of potassium/silicon = 0.16 to 0.26, so the dimensional shrinkage rate of the resin film can be reduced. In addition, the use of synthetic mica can improve the adhesion and dimensional stability of the resin film, and prevent deterioration of the dielectric properties of the resin film due to moisture absorption.

According to the present invention, there is an effect that it is possible to improve adhesion and reduce the dimensional shrinkage rate. In addition, since the amount of particles with a particle size of 1 μm or less is 20% or less of the total particles of synthetic mica, it is possible to contribute to reducing the dimensional shrinkage rate of the resin film after etching during the manufacture of the circuit board. In addition, it is possible to prevent the mica from easily agglomerating.

According to the invention described in claim 2, the ratio of potassium to silicon when measured by an electron probe microanalyzer is in the range of potassium/silicon = 0.21 to 0.26, so that the strength of the resin film base material is improved and further improvement in adhesion can be expected.
According to the invention described in claim 3, the composition contains at least 100 parts by mass of polyarylene ether ketone resin and 20 parts by mass or more and 80 parts by mass or less of synthetic mica, so that, for example, when a resin film and a copper foil are adhered to each other, the adhesion can be improved.
According to the fourth aspect of the present invention, since the synthetic mica is non-swelling, it is possible to suppress dimensional changes in the resin film caused by moisture absorption and to prevent deterioration of the dielectric properties of the resin film.

According to the fifth aspect of the present invention , since the D95 value of the synthetic mica is set to 35 μm or less, an improvement in the mechanical strength of the resin film can be expected.

According to the sixth aspect of the present invention , since the specific surface area of the synthetic mica is set to 3.0 m ² /g or more, it is possible to reduce the dimensional shrinkage rate of the resin film after etching.
According to the invention described in claim 7 or 8 , the resin film described in any one of claims 1 to 6 is used, so that when manufacturing a circuit board, it is possible to simultaneously achieve improved adhesion and mechanical strength of the resin film and a reduced dimensional shrinkage rate of the resin film after etching.

1 is a cross-sectional view illustrating an embodiment of a resin film and a copper-clad laminate according to the present invention. FIG. FIG. 2 is a cross-sectional view illustrating a second embodiment of the resin film and the copper-clad laminate according to the present invention.

A preferred embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the resin film 1 in this embodiment is a film for copper-clad laminates 3 or circuit boards, which is formed into a long strip from a molding material containing at least polyarylene ether ketone resin and synthetic mica, and has a potassium/silicon ratio of 0.16 to 0.26 in the synthetic mica as measured by an electron probe microanalyzer. The film contributes to the achievement of Goal 9 of the SDGs (the United Nations' international goals for sustainable development, consisting of 17 global goals and 169 targets (achievement criteria)) adopted at the United Nations Summit.

The molding material contains at least polyarylene ether ketone (PAEK) resin and synthetic mica, and other resins and various fillers are selectively blended as necessary to form the thin resin film 1 shown in Figure 1. This molding material contains 100 parts by mass of polyarylene ether ketone resin and 20 to 80 parts by mass of synthetic mica, preferably 100 parts by mass of polyarylene ether ketone resin and 45 to 65 parts by mass of synthetic mica.

The synthetic mica content is 20 parts by mass or more and 80 parts by mass or less because, if it is less than 20 parts by mass, the dimensional shrinkage rate of the resin film 1 after etching during the manufacture of a circuit board deteriorates, and the adhesion of the resin film 1 decreases. On the other hand, if it exceeds 80 parts by mass, the adhesion of the resin film 1 decreases, and the hardness of the resin film 1 increases more than necessary, making it more likely to crack.

The molding material, polyarylene ether ketone resin, is a thermoplastic crystalline resin consisting of arylene groups, ether groups, and carbonyl groups, and examples of such resins include those described in Patent Publication No. 5709878 and Patent Publication No. 5847522, or in the literature (Asahi Research Center Co., Ltd.: PEEK, a super engineering plastic growing in cutting-edge applications (Part 1)). It has a melting point of 300°C to 400°C and is excellent in electrical insulation, mechanical properties, heat resistance, chemical resistance, radiation resistance, hydrolysis resistance, low water absorption, and recyclability.

Specific examples of polyarylene ether ketone resins include polyether ether ketone (PEEK) resin, polyether ketone ketone (PEKK) resin, polyether ketone (PEK) resin, polyether ketone ether ketone ketone (PEKEKK) resin, etc. Among these, polyether ether ketone resin is the most suitable because it can obtain the optimal processing temperature for manufacturing copper-clad laminate 3 and circuit boards and is also inexpensively available.

Examples of polyether ether ketone resin products include Victrex's Victrex Powder series and Victrex Granules series, Daicel-Evonik's VestaKeep series, and Solvay Specialty Polymers' KetaSpire PEEK series. Examples of polyether ketone ketone resin products include Arkema's KEPSTAN series. Examples of polyether ketone resin products include Victrex's HT G22 and HT G45. Examples of polyether ketone ether ketone ketone resin products include Victrex's ST G45.

The polyarylene ether ketone resin may be used alone or in a mixture of two or more types, or may be a copolymer. The polyarylene ether ketone resin is usually used in a form suitable for molding, such as powder, granules, or pellets. There are no particular limitations on the method for producing the polyarylene ether ketone resin, but for example, the method described in the literature [Asahi Research Center Co., Ltd.: PEEK, a super engineering plastic growing in cutting-edge applications (Part 1)] is used.

The synthetic mica used as the molding material is fluorine tetrasilicic mica or fluorine phlogopite, etc., whose main components are fluorine (F), magnesium (Mg), silicon (Si), and potassium (K), and functions to suppress deterioration of dielectric properties due to moisture absorption and contribute to the adhesion and dimensional stability of the resin film 1. This synthetic mica is classified into non-swelling, swelling, lipophilic, etc., but non-swelling is preferred, as it suppresses dimensional changes and deterioration of dielectric properties of the resin film 1 due to moisture absorption and also has excellent heat resistance.

Synthetic mica is composed of many mica particles of different particle sizes, with the amount of mica particles with a particle size of 1 μm or more, for example, an average particle size of 3.4 μm to 13 μm, being 80% or more of the total, and the amount of mica particles with a particle size of 1 μm or less being 20% or less of the total, preferably 0.1% to 20%, more preferably 0.15% to 10%. This is because if the amount of mica particles with a particle size of 1 μm or less exceeds 20% of the total mica particles, it is not possible to reduce the dimensional shrinkage rate of the resin film 1 after etching during the manufacture of the circuit board, and the mica particles are more likely to aggregate.

The specific surface area of the synthetic mica is 3.0 m ^{2 /g or more, preferably 3.0 m 2} /g to 15 m 2 /g, more preferably 3.5 m ² /g to 15 m ² /g, and even more preferably 3.5 m ² /g to 9.71 m ² /g, in order to reduce the dimensional shrinkage ^rate of the resin film 1 after etching during the manufacture of the circuit board. The specific surface area of the synthetic mica is 3.0 ^{m 2 /} g or more because if the specific surface area of the synthetic mica is less than 3.0 m ² /g, it will contain a large amount of aggregates or coarse particles. The specific surface area of the mica particles can be measured by a permeation method or various gas adsorption methods, but it is preferable to measure it in accordance with JIS Z 8830:2013.

The median diameter D50 of synthetic mica should be 2.0 μm or more and 10 μm or less. The reason for selecting the median diameter (central diameter) rather than the average diameter or the most frequent diameter is that it is suitable for grasping a representative value of the particle size distribution of mica particles and is convenient when comparing the size of the particle size distribution of multiple samples. The median diameter D50 of synthetic mica is optimally 2.0 μm or more and 10 μm or less, preferably 2.0 μm or more and 6.0 μm or less, and more preferably 2.8 μm or more and 5.10 μm or less, in order to improve the film-forming properties of the resin film 1.

From the viewpoint of improving the mechanical strength of the resin film 1, the D95 value of the synthetic mica is optimally 35 μm or less, preferably 6.00 μm or more and 35 μm or less, and more preferably 6.00 μm or more and 16 μm or less. A specific example of such a synthetic mica product is the Micromica MK series (product name: manufactured by Katakura Co-op Agri Co., Ltd.).

In addition to the above resins and synthetic mica, various fillers can be added to the molding material as long as they do not impair the characteristics of the present invention. For example, silica, boron nitride (BN), calcium carbonate, antioxidants, light stabilizers, UV absorbers, plasticizers, lubricants, flame retardants, antistatic agents, heat resistance improvers, inorganic compounds, organic compounds, etc. can be selectively added.

The resin film 1 is formed from such molding materials, and the molding method can be any of melt extrusion, calendar molding, casting, etc. However, when considering ease of handling and simplification of manufacturing equipment, melt extrusion is optimal. When manufacturing the resin film 1 using this melt extrusion method, a thin resin film 1 can be produced by melt-kneading the molding material using an extrusion molding machine, and continuously extruding the resin film 1 from the T-die of the extrusion molding machine and cooling it.

In the above, when the resin film 1 is manufactured, the prepared molding material is first fed into the raw material inlet of the melt extruder, preferably while supplying an inert gas, and the molding material is melt-kneaded in the melt extruder heated to a temperature below the thermal decomposition temperature. From the viewpoint of dispersibility and workability, the molding material is preferably prepared by adding synthetic mica to molten polyarylene ether ketone and melt-kneading the two. The melt extruder is not particularly limited, but may be, for example, a single-screw extruder, a twin-screw extruder, or a triple-screw extruder.

After the molding materials are melted and kneaded in a melt extrusion molding machine, a strip-shaped resin film 1 is continuously extruded from a T-die at the tip of the melt extrusion molding machine, and this resin film 1 is wound in sequence around multiple cooling rolls, a pair of pressure rolls, a tension roll, and a winding core of a winding machine, and cooled by sliding it against multiple cooling rolls. After both sides of the resin film 1 are cut with a slit blade to adjust the appearance, the resin film 1 is wound in sequence around the winding core of the winding machine to form the original roll of resin film 1, and the resin film 1 can be manufactured.

The thickness of the produced resin film 1 is not particularly limited, but considering the strength, rigidity, productivity, and versatility as a base for a circuit board, it is optimal to have a thickness of 2 μm to 1000 μm, preferably 10 μm to 250 μm, and more preferably 50 μm to 100 μm. The thickness of this resin film 1 can be measured using a dedicated micrometer, etc.

The ratio of potassium (K) to silicon (Si) among the main components of the synthetic mica in the produced resin film 1 is preferably in the range of K/Si = 0.16 to 0.26, preferably 0.21 to 0.26, and more preferably 0.21 to 0.24, when measured with an electron probe microanalyzer (EPMA). Examples of electron probe microanalyzers include the EPMA-1720 Series (manufactured by Shimadzu Corporation: product name) and JXA-8100 (manufactured by JEOL Ltd.: product name).

From experimental results, the maximum tensile strength of the produced resin film 1 is 50 N/mm2 or ^more , preferably 50 N/mm2 or ^more and 120 N/mm2 or ^less , and more preferably 80 N/ ^mm2 or more and 120 N/mm2 ^or less. The tensile strength of this resin film 1 can be measured in accordance with, for example, JIS K 7127:1999.

The dielectric loss tangent of the produced resin film 1 at a frequency of about 28 GHz is, from experimental results, 0.0040 to 0.0051, preferably 0.0043 to 0.0051. The dielectric loss tangent of this resin film 1 is not particularly limited, but can be measured by the Fabry-Perot method using an open-type interferometer, a method for determining the relative dielectric constant and dielectric loss tangent at high frequencies by the cavity resonator perturbation method, a three-terminal measurement method using a mutual induction bridge circuit, etc. Among these, the Fabry-Perot method and the cavity resonator perturbation method, which have excellent high resolution, are the most suitable.

Next, when manufacturing the copper-clad laminate 3 using the resin film 1, the resin film 1 and the copper foil 2 having the above-mentioned characteristics are prepared, and the resin film 1 and the copper foil 2 are directly stacked on top of each other to laminate them. The thickness range of the copper foil 2 is specified to be 2 μm or more and 100 μm or less, preferably 10 μm or more and 50 μm or less, because if the thickness is less than 2 μm, it will be difficult to handle during manufacturing and use, and if it exceeds 100 μm, it will take a long time to manufacture.

The laminated surface of the copper foil 2 may be either the front or back surface of the copper foil 2. When the copper foil 2 is an electrolytic copper foil produced by an electrolytic manufacturing device, the electrolytic copper foil has a smooth and glossy shiny (S) surface on the drum-shaped cathode side and a matte (M) surface on the opposite side of the shiny surface, and either the shiny surface or the matte surface can be used as the laminated surface. Examples of such copper foil 2 products include TQ-M7-VSP (product name manufactured by Mitsui Mining & Smelting Co., Ltd.), 3EC-III (product name manufactured by Mitsui Mining & Smelting Co., Ltd.), and CF-T49A-DS-HD2-12 (product name manufactured by Fukuda Metal Foil & Powder Co., Ltd.).

The opposing surfaces of the resin film 1 and the copper foil 2 do not need to be treated in any particular way, but at least one of the opposing surfaces may be selectively treated with corona treatment, plasma treatment, or ultraviolet light treatment. By applying these treatments, it is possible to improve the strength, adhesion, and cleanability.

After the resin film 1 and copper foil 2 are laminated, they are placed in a hot press or between rolls and heated and pressed to produce a copper-clad laminate 3 in which the resin film 1 and copper foil 2 are integrated. The optimum temperature for hot pressing is between the melting point of the resin film 1 -20°C and +20°C, preferably between the melting point of the resin film 1 -20°C and +10°C.

The melting point of the resin film 1 varies depending on the presence or absence of filler in the molding material, but for example, when it is 340°C, the temperature range for thermocompression bonding is set to 320°C or higher and 360°C or lower. This is because if the melting point of the resin film 1 is less than -20°C, the polyarylene ether ketone resin on the opposing surface will not melt. Also, if it exceeds 360°C, the fluidity of the molding material increases, so the thickness of the resin film 1 is likely to fluctuate, and the thickness precision of the copper-clad laminate 3 deteriorates.

The shrinkage rate of the resin film 1 in the copper-clad laminate 3 is less than 0.30%, preferably 0.08% to 0.28%, when measured under conditions of 150°C x 30 min in accordance with JIS C 6481:1996. In addition, the adhesion strength of the resin film 1 in the copper-clad laminate 3, in other words, the peel strength, is 5.0 N/cm or more, preferably 7.0 N/cm or more, more preferably 7.5 N/cm or more, when measured in accordance with JIS Z 0237:2009 (Test method for adhesive tapes and adhesive sheets) in order to ensure practicality and reliability. There is no particular limit to the upper limit of the adhesion strength, but it is generally good to have it be 15 N/cm or less.

Next, when manufacturing a circuit board such as a flexible board using the copper-clad laminate 3, a photoresist layer for etching is laminated onto the exposed surface of the copper foil 2 of the copper-clad laminate 3, processing holes are drilled in predetermined locations of this laminated intermediate body, the photoresist layer is exposed to ultraviolet light, and developed to dissolve the photoresist layer in the unexposed areas, revealing the circuit pattern.

Next, the circuit pattern of the intermediate is etched to remove the photoresist layer, the intermediate is washed and dried, a cover film is attached to most of the intermediate to form an insulating layer, and exposed terminals and the like are subjected to surface treatment such as plating. The shrinkage rate of the resin film 1 after etching is less than 0.30%, and preferably 0.04% to 0.27%, optimally when measured in accordance with JIS C 6481:1996. Once the intermediate has been subjected to surface treatment such as plating, the intermediate is externally machined, the conductivity of the circuit pattern is electrically checked, and a final inspection is carried out to manufacture the circuit board.

As described above, when the potassium to silicon ratio of the synthetic mica in the resin film 1 is in the range of potassium/silicon = 0.16 to 0.26, the dimensional shrinkage rate of the resin film 1 can be reduced, so that the dimensional shrinkage rate of the resin film 1 after etching or heating at 150°C can be reduced.

To explain the ratios and effects in detail, since the crystal structure of synthetic mica has a structure in which potassium (K) is contained between the crystal layers, it is believed that the lower the ratio of potassium, the thinner the synthetic mica particles will be. Therefore, for example, the smaller the ratio of potassium, the greater the number of particles in 1 g of synthetic mica. It is presumed that when the number of synthetic mica particles exceeds a certain level, it becomes difficult to form a uniform dispersion distribution structure in the polyarylene ether ketone resin. From the above, it is presumed that in the case of a resin film 1 with a K/Si of less than 0.16, the dispersion distribution in the polyarylene ether ketone resin deteriorates, and therefore the effect of reducing the heat shrinkage rate at 150°C is reduced.

In contrast, in the case of resin film 1 with K/Si exceeding 0.26, although it has excellent dispersion and distribution in the polyarylene ether ketone resin, it is presumed that this is because the amount of potassium contained in the synthetic mica crystal structure is large and the thickness of the mica particles is large, so that the contribution rate of resin film 1 to the effect of reducing the shrinkage rate in the planar direction is slightly replaced by the contribution rate in the thickness direction. In other words, it is presumed that the shrinkage rate in the planar direction of resin film 1 when heated is large.

When the ratio of potassium to silicon is limited to the narrow range of potassium/silicon = 0.21 to 0.26, the dimensional shrinkage rate of the resin film 1 can be reduced, and the strength of the base material of the resin film 1 can be further improved, significantly improving adhesion. Furthermore, since synthetic mica, which has excellent adhesion to metals, is used instead of natural mica, the adhesion and dimensional stability of the resin film 1 can be improved, and deterioration of the dielectric properties due to moisture absorption by the resin film 1 can be suppressed.

Next, FIG. 2 shows a second embodiment of the present invention, in which copper foil 2 is directly laminated on both sides of resin film 1, and then the resulting laminate is sandwiched between a hot press machine or rolls and heated and pressed to thermocompress, producing a copper-clad laminate 3 in which the resin film 1 and a pair of copper foils 2 are integrated. The rest of the structure is similar to the above embodiment, so a description thereof will be omitted.

The same effects as those of the above embodiment can be expected from this embodiment, and it is clear that this embodiment can be of great use in the manufacture of double-sided circuit boards that can form complex circuits by crossing the wiring.

In the above embodiment, the resin film 1 is used for a circuit board, but this is not limited to this. For example, the resin film 1 may be used for other purposes, such as audio equipment.

Examples of the resin film and the copper-clad laminate according to the present invention will be described below together with comparative examples.
Polyarylene ether ketone resin and seven types of synthetic mica were prepared to manufacture the resin films used in Examples 1 to 8 and Comparative Examples 1 to 3. As the polyarylene ether ketone resin, a polyether ether ketone (PEEK) resin having a melting point of 341° C. and a glass transition temperature of 147° C. (manufactured by Victrex: product name Victrex Granules series 450G) or a polyether ketone ketone (PEKK) resin having a melting point of 360° C. and a glass transition temperature of 165° C. (manufactured by Arkema: product name KEPSTAN series 8002) was used (see Table 4).

The seven types of synthetic mica were analyzed for the elements contained in them using an X-ray fluorescence analyzer (Shimadzu Corporation: product name EDX-8000). Specifically, the synthetic mica powder was evacuated into a vacuum inside the analyzer, and then qualitative and quantitative analysis was performed using the metal oxide measurement mode. The quantitative results of the metal oxides, etc. obtained were then converted into ratios of metal elements, etc., and the results are shown in Table 2.

For example, when synthetic mica 1 was analyzed, _SiO2 (55.3%), MgO (26.5%), _K2O (8.5%), CaO (0.29%), _Fe2O3 (0.17%), _Al2O3 (0.10% ₎ , and F ( _9.17 %) were detected, and the ratio of each element in the total of 100% was clarified. Based on the values of the molecular weight and atomic weight of the following metal oxides and F, the ratio of each metal element and F was calculated and summarized in Table 2.

Molecular weight and atomic weight of metal oxide and F SiO ₂ : 60.1
MgO: 40.3
_K2O : 94.2
CaO: 56.1
_Fe2O3 : _159.7
Al2O3 : _102.0
F: 19.0

Calculation example: In the case of _SiO2 , 55.3 (ratio of _SiO2 determined by X-ray fluorescence analysis) ÷ 60.1 (molecular weight of _SiO2 ) = 0.920.
In the case of MgO, the formula is 26.5 (the ratio of MgO determined by X-ray fluorescence analysis)÷40.3 (the molecular weight of MgO)=0.657.
In the case of K ₂ O, the ratio is 8.5 (the ratio of K ₂ O determined by X-ray fluorescence analysis)÷94.2 (the molecular weight of K ₂ O)×2=0.18.
Similar calculations were performed for other metal oxides and F. In this way, calculations were performed from the results of the fluorescent X-ray analysis measurement of each synthetic mica particle, and the results are summarized in Table 2.

The seven types of synthetic mica are: synthetic mica 1 for comparison, MK-100DS with K/Si = 0.78 [product name manufactured by Katakura Coop Agri Co., Ltd.]; synthetic mica 2, MK-PDS with K/Si = 0.67 [product name manufactured by Katakura Coop Agri Co., Ltd.]; synthetic mica 3, MK-PGDS with K/Si = 0.66 [product name manufactured by Katakura Coop Agri Co., Ltd.]; synthetic mica 4, FGMK80DS with K/Si = 0.73 [product name manufactured by Katakura Coop Agri Co., Ltd.]; Synthetic mica 5 was MK100PG/60-0 with K/Si = 0.56 [product name manufactured by Katakura Coop Agri Co., Ltd.], synthetic mica 6 was MK100PG/60-6 with K/Si = 0.55 [product name manufactured by Katakura Coop Agri Co., Ltd.], and synthetic mica 7 for comparison was MK100PG/40-6 with K/Si = 0.37 [product name manufactured by Katakura Coop Agri Co., Ltd.] (see Table 1).

The elemental ratios of each synthetic mica were detected by X-ray fluorescence analysis, and are shown in Table 2. The results of converting the data in Table 2 are shown in Table 3. Examples of calculation formulas for Table 3 are (Mg ratio) ÷ (Si ratio) x 4 = 0.657 ÷ 0.920 x 4 = 2.86, (K ratio) ÷ (Si ratio) x 4 = 0.180 ÷ 0.920 x 4 = 0.78.

The particle size distribution of the synthetic mica was measured in accordance with JIS Z 8825:2013. Water was used as the dispersion liquid for this measurement, and the volume distribution was evaluated by laser diffraction/scattering using a particle size distribution measuring device (manufactured by Microtrac-Bell Co., Ltd.: product name: MT3300EXII) and summarized in Table 1. The specific surface area of the synthetic mica was also measured in accordance with JIS Z 8830:2013.

Example 1
First, a resin film having a thickness of 100 μm was melt-extruded from a molding material containing polyether ether ketone resin and synthetic mica 2. As shown in Table 4, the mass of the molding material was 100 parts by mass of polyether ether ketone resin and 45 parts by mass of synthetic mica 2.

After the resin film was melt extrusion molded, the ratio of the constituent elements of this resin film was measured using an electron probe microanalyzer (EPMA) [product name: JXA-8100] manufactured by JEOL Ltd. under conditions of an acceleration voltage of 15 kV, an irradiation diameter of φ100 μm, and an irradiation current of 50 nA. A gold vapor deposition layer of approximately 150 nm thickness was formed on the surface of the resin film using a vacuum deposition device to prepare a measurement sample. In addition, measurements using the EPMA were performed at three randomly selected positions on the measurement sample, and the average of the results of the three measurements was calculated. From the measurement results, elements such as C, O, F, Mg, Si, K, and Ca were mainly detected, and the atomic percentages of F, Mg, Si, K, and Ca are listed in Tables 5 and 6.

Next, the resin film and the prepared copper foil were cut to 320 mm x 320 mm and directly laminated together, then sandwiched between 1 mm thick SUS plates and heat-pressed for 5 minutes at a surface pressure of 4 MPa using a heat press machine with a hot plate set to 350°C, before being removed to produce a two-layer copper-clad laminate. The copper foil used was 12 μm thick TQ-M7VSP (product name: manufactured by Mitsui Mining & Smelting Co., Ltd.).

After preparing the two-layered copper-clad laminate, the shrinkage rate of the resin film of the copper-clad laminate after etching, the shrinkage rate after treatment under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of around 28 GHz were measured and evaluated, and are shown in Table 5. The shrinkage rate after etching the resin film and after treatment under conditions of 150°C x 30 min was measured in accordance with JIS C 6481:1996. Specifically, the copper-clad laminate was cut to 300 x 300 mm, punch holes were made at four ends, and the distance between the punch holes was measured in the extrusion direction and width direction. Using this measured distance as a reference, measurements were made at the same punch hole positions after etching and after treatment under conditions of 150°C x 30 min, and the shrinkage rate was calculated from the dimensional change.

Shrinkage rate after etching of resin film The laminated copper foil was dissolved in an aqueous solution of iron chloride to prepare a resin film as a test specimen, and measurements were made in the extrusion direction and width direction of the resin film. A two-dimensional length measuring machine (product name: VMH600, manufactured by Mino Group Co., Ltd.) was used to measure the dimensions.

Shrinkage rate under conditions of 150°C x 30 min Next, measurements were made in the extrusion direction and width direction of the resin film under conditions of 150°C x 30 min. Specifically, after processing in a hot air circulation thermostatic chamber for a specified time and temperature, the resin film was cooled to room temperature, and the length of the resin film was measured for the same portion previously measured. A two-dimensional length measuring machine (product name: VMH600, manufactured by Mino Group Co., Ltd.) was used to measure the dimensions. The target shrinkage rate of the resin film after 150°C was set to less than 0.30%.

Adhesion of copper-clad laminates: The adhesion of copper-clad laminates was measured by cutting the copper-clad laminates into test specimens with a width of 25 mm, and fixing the copper-clad laminates to a support and fixing the copper foil to a pulling tool at a peel speed of 0.3 mm/min and a peel angle of 180°, and measuring the peel strength when the copper foil was pulled from the copper-clad laminate, according to JIS Z0237:2009. The adhesion was evaluated as ◯ for 7 N/cm or more, △ for 5 N/cm or more, and × for less than 5 N/cm.

Maximum tensile strength of copper-clad laminate The maximum tensile strength of the resin film in the copper-clad laminate was evaluated as the maximum tensile strength at 23°C. The tensile strength was measured in the extrusion direction and width direction (perpendicular to the extrusion direction) of the resin film. The measurement was performed in accordance with JIS K7127 at a pulling speed of 50 mm/min and a temperature of 23°C. The measured maximum tensile strength was evaluated by indicating 80 Nmm2 ^or more as ○ and 50 Nmm2 ^or more as △.

The dielectric tangent of the copper-clad laminate was measured using an electronic measuring device (product name: Compact USB Vector Network Analyzer MS46122B, manufactured by Anritsu Corporation) by the Fabry-Perot method, which is a type of open resonator method, at a frequency of around 28 GHz, when dry and after immersion in water for 24 hours.

Specifically, the copper foil was dissolved in an aqueous iron chloride solution to remove the resin film, which was then cut to 100 x 100 mm. The cut test pieces were then left in a constant temperature and humidity room at 23±2°C and 50±10% RH for at least 10 hours, after which the values measured using the Fabry-Perot method were used to determine the dielectric tangent before immersion in water. For measurements 24 hours after immersion in water, the test pieces whose dielectric properties were measured before immersion were immersed in ion-exchanged water for 24 hours, then removed, and the water adhering to the surface of the copper-clad laminate was wiped off with paper. The test pieces were then left in an environment of 23±2°C and 50±10% RH for 5 minutes, after which measurements were made using the Fabry-Perot method. All measurements at 50% RH before immersion and after 24 hours of immersion were performed in an environment of 23±2°C and 50±10% RH.

The resonator used was an open-type resonator (product name: Fabry-Perot resonator, Model No. DPS03, manufactured by Keycom). For the measurement, a copper-clad laminate was placed on the sample stage of the open-type resonator fixture, and a vector network analyzer was used to perform the measurement using the Fabry-Perot method, which is a type of open-type resonator method. Specifically, the dielectric loss tangent was measured using a resonance method that utilizes the difference in resonance frequency between a state in which the copper-clad laminate was not placed on the sample stage and a state in which the copper-clad laminate was placed on the sample stage. The specific frequency used for the measurement was 28 GHz. The target value for the dielectric loss tangent tan δ after 24 hours of water immersion was less than 0.0080, and a good value was 0.0075 or less.

Example 2
The procedure was basically the same as in Example 1, but the amount of polyether ether ketone resin was changed to 100 parts by mass, and the amount of synthetic mica 3 was changed to 45 parts by mass.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 5.

Example 3
The procedure was basically the same as in Example 1, but the amount of polyether ether ketone resin was changed to 100 parts by mass, and the amount of synthetic mica 3 was changed to 45 parts by mass. Also, a resin film having a thickness of 50 μm was melt extrusion molded instead of a thickness of 100 μm.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 5.

Example 4
Basically, the same as in Example 1, but the amount of polyether ketone ketone resin was changed to 100 parts by mass and the amount of synthetic mica 3 was changed to 45 parts by mass. In addition, after the resin film was melt-extruded, the resin film and the prepared copper foil were cut to 320 mm x 320 mm, and directly laminated, and these were sandwiched between SUS plates with a thickness of 1 mm, and the heat pressing was performed for 5 minutes at a surface pressure of 4 MPa using a hot press machine with a hot plate set to 370 ° C., and then removed to produce a two-layer copper-clad laminate. The copper foil used was TQ-M7VSP [product name: manufactured by Mitsui Mining & Smelting Co., Ltd.] with a thickness of 12 μm.

The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of around 28 GHz were measured and evaluated, and are shown in Table 5.

Example 5
The procedure was basically the same as in Example 1, but the amount of polyether ether ketone resin was changed to 100 parts by mass, and the amount of synthetic mica 3 was changed to 65 parts by mass.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 5.

Example 6
The procedure was basically the same as in Example 1, but the amount of polyether ether ketone resin was changed to 100 parts by mass, and the amount of synthetic mica 6 was changed to 45 parts by mass.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 5.

Example 7
The procedure was basically the same as in Example 1, but the amount of polyether ether ketone resin was changed to 100 parts by mass, and the amount of synthetic mica 5 was changed to 45 parts by mass.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 5.

Example 8
The procedure was basically the same as in Example 1, but the amount of polyether ether ketone resin was changed to 100 parts by mass, and the amount of synthetic mica 3 was changed to 85 parts by mass.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 5.

Comparative Example 1
Basically, the procedure was the same as in Example 1, but a resin film having a thickness of 100 μm was melt extrusion molded from a molding material containing polyether ether ketone resin and synthetic mica 1. As shown in Table 4, the mass of the molding material was 100 parts by mass of polyether ether ketone resin and 45 parts by mass of synthetic mica 1.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 6.

Comparative Example 2
The procedure was basically the same as in Example 1, but a resin film having a thickness of 100 μm was melt extrusion molded from a molding material containing polyether ether ketone resin and synthetic mica 7. As shown in Table 4, the mass of the molding material was 100 parts by mass of polyether ether ketone resin and 45 parts by mass of synthetic mica 7.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 6.

Comparative Example 3
Basically, the procedure was the same as in Example 1, but a resin film having a thickness of 100 μm was melt extrusion molded from a molding material containing polyether ether ketone resin and synthetic mica 4. As shown in Table 4, the mass of the molding material was 100 parts by mass of polyether ether ketone resin and 45 parts by mass of synthetic mica 4.
The shrinkage rate after etching of the resin film of the dried copper-clad laminate, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz were measured and evaluated, as shown in Table 6.

〔evaluation〕
In the case of Examples 1 to 7, the ratio of potassium to silicon in the synthetic mica of the resin film was within the range of K/Si = 0.16 to 0.26, so excellent results were obtained with respect to the shrinkage rate after etching of the resin film, the shrinkage rate under the condition of 150 ° C. x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of about 28 GHz.

In the case of Example 8, excellent results were obtained in terms of the shrinkage rate after etching of the resin film, the shrinkage rate under conditions of 150°C x 30 min, the maximum tensile strength, and the dielectric tangent at a frequency of around 28 GHz. However, since the synthetic mica 3 was changed to 85 parts by mass, adhesion decreased, regardless of practicality. Therefore, the optimal amount of synthetic mica is 20 parts by mass or more and 80 parts by mass or less.

In contrast, in the case of each comparative example, the potassium to silicon ratio of the synthetic mica in the resin film was outside the range of K/Si = 0.16 to 0.26, so problems arose with the shrinkage rate after etching of the resin film, the shrinkage rate under conditions of 150°C x 30 min, adhesion, maximum tensile strength, and dielectric tangent at a frequency of around 28 GHz.

The resin film, copper-clad laminate, and circuit board of the present invention are used in fields such as information and communications and automotive equipment.

1 Resin film 2 Copper foil 3 Copper-clad laminate

Claims (8)

A resin film molded from a molding material containing at least a polyarylene ether ketone resin and synthetic mica, in which the amount of particles having a particle diameter of 1 μm or less among all the particles of the synthetic mica is 20% or less ,
The ratio of potassium to silicon as measured by electron probe microanalyzer is:
Potassium/silicon = 0.16 to 0.26
A resin film characterized in that The ratio of potassium to silicon as measured by electron probe microanalyzer is:
Potassium/silicon = 0.21 to 0.26
The resin film according to claim 1, wherein the thickness of the resin film is within the range of 100 nm to 150 nm. The resin film according to claim 1 or 2, wherein the molding material contains at least 100 parts by mass of polyarylene ether ketone resin and 20 parts by mass or more and 80 parts by mass or less of synthetic mica. The resin film according to claim 1, 2, or 3, in which the synthetic mica is non-expandable synthetic mica. 5. The resin film according to claim 1, wherein the synthetic mica has a D95 value of 35 μm or less. 6. The resin film according to claim 1 , wherein the specific surface area of the synthetic mica is 3.0 m ² /g or more. 7. A copper-clad laminate comprising the resin film according to claim 1 , and a copper foil laminated and attached to at least one of the two surfaces of the resin film. A circuit board comprising the resin film according to any one of claims 1 to 6 .

Images