WO2025057749A1 - Copper-clad laminate and method for producing same - Google Patents

Abstract

[Problem] To provide: a copper-clad laminate that, while suppressing transmission losses, can realize a high adhesion strength between a low dielectric resin film and an electroless copper plating layer; and a method for producing this copper-clad laminate. [Solution] A copper-clad laminate according to the present invention characteristically comprises: a low dielectric resin film that at a frequency of 10 GHz has a dielectric constant of less than 3.2 and a dielectric loss tangent of 0.008 or less; and an electroless copper plating layer that is directly laminated on at least one surface of the low dielectric resin film.

Description

Copper clad laminate and method for producing same

The present invention relates to a copper clad laminate for flexible circuit boards mounted on communication devices and the like, a method for producing the same, and a flexible circuit board made from the copper clad laminate.

2. Description of the Related Art In recent years, electronic devices have become significantly smaller and more powerful, and this is due in large part to the development of communication devices that use radio waves, such as mobile phones and wireless LANs.
In particular, in recent years, with the increasing volume of information, as exemplified by big data brought about by the IoT, communication signals between electronic devices are becoming increasingly higher in frequency, and the circuit boards mounted on such communication devices require materials with low transmission loss (dielectric loss) in the high-frequency range.

It is known that the dielectric loss that occurs in this circuit board is proportional to the product of three elements: the "frequency of the signal," the "square root of the dielectric constant of the board material," and the "dielectric tangent." Therefore, to obtain the excellent dielectric characteristics described above, a material with as low a dielectric constant and dielectric tangent as possible is required.

In such circuit boards, the circuits are generally formed from a metal such as copper. The copper layer in this circuit board is formed, for example, by the lamination method shown in Patent Document 1, the casting method shown in Patent Document 2, or the plating method shown in Patent Document 3.

Patent No. 6202905 Patent No. 5186266 JP 2002-256443 A International Publication No. 2021/039370 International Publication No. 2022/030644 International Publication No. 2022/030645

As mentioned above, reducing transmission loss in high-frequency communications has become an important development element in recent years, and resin films with low transmission loss (hereinafter also referred to as "low dielectric films" or "low dielectric resin films") are beginning to be used as base materials for flexible circuit boards.
Such flexible circuit boards (hereinafter also referred to as "FPCs") are formed by forming a conductive coating of copper or the like on a low dielectric film by, for example, a sputtering method, a plating method, etc. When manufacturing FPCs by the sputtering method, the manufacturing process becomes complicated, and many problems remain in terms of productivity and cost.

In contrast, the plating methods shown in Patent Documents 3 to 6 ensure relatively good adhesion between the copper layer and resin films with high dielectric constants. However, these patent documents also carry out a surface modification process in which a mixture of an alkaline aqueous solution and an amino alcohol is applied to the surface of the resin film. As a result of continued investigations by the inventors, they have concluded that such surface modification by wet processing alone does not necessarily result in successful cleavage of molecules present on the surface of the resin film or generation of functional groups, and that there are cases in which the catalyst, which acts as the precipitation nucleus for electroless Cu plating, cannot be supported on the film surface.

The present invention aims to solve the above-mentioned problems by way of example, and aims to provide a copper-clad laminate that can achieve high adhesion between a low dielectric resin film and an electroless copper plating layer while suppressing transmission loss, and a method for manufacturing the same.

In order to solve the above-mentioned problems, the copper clad laminate in one embodiment of the present invention may include a low dielectric resin film having a relative dielectric constant of less than 3.2 at a frequency of 10 GHz and a dielectric loss tangent of 0.008 or less, and an electroless copper plating layer laminated directly onto at least one surface of the low dielectric resin film.

In order to solve the above-mentioned problems, a copper clad laminate in one embodiment of the present invention includes a low dielectric resin film having a relative dielectric constant of 3.2 or more and a dielectric loss tangent of 0.008 or less at a frequency of 10 GHz, and an electroless copper plating layer on at least one surface of the low dielectric resin film, and in a peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film, an area ratio (P area2 /P area1 ) of a peak area (P _area2 ) of the low dielectric resin film from 282.0 eV to 290.0 eV of the low dielectric resin film to a peak area (P _area1 ) of an original sheet of the low _dielectric resin film analyzed under the same conditions may be 1.25 or more and _2.00 or less.

Furthermore, in order to solve the above-mentioned problems, the manufacturing method of a copper clad laminate in one embodiment of the present invention is (10) a manufacturing method of a copper clad laminate manufactured by forming an electroless copper plating layer on a low dielectric resin film having a relative dielectric constant of 3.5 or less at a frequency of 10 GHz and a dielectric loss tangent of 0.008 or less, and may include a step of performing a first surface modification treatment on the surface of the low dielectric resin film by vacuum plasma treatment, and an electroless copper plating step of directly laminating an electroless copper plating layer on the surface of the low dielectric resin film that has been surface modified by the vacuum plasma treatment.

The present invention makes it possible to suppress transmission loss while ensuring high adhesion at the interface between the low dielectric film and the electroless copper plating layer.

1 is a schematic diagram showing a copper clad laminate 10 (a low dielectric resin film 1 having an electroless copper plating layer 5 formed thereon) in this embodiment. 1 is a schematic diagram showing a copper clad laminate 20 (a low dielectric resin film 1 on which an electrolytic copper plating layer 6 and an electroless copper plating layer 5 are formed) in this embodiment. 1 is a schematic diagram showing the interface state between a low dielectric resin film 1 and an electroless copper plating layer 5 in a copper clad laminate 10 of the present embodiment. 1 is a schematic diagram showing a configuration of a vacuum plasma processing apparatus 100 according to the present embodiment. FIG. 2 is a schematic diagram showing a change in XPS spectrum due to a vacuum plasma treatment of SPS. FIG. 2 is a schematic diagram showing a change in the XPS spectrum due to a vacuum plasma treatment of PFA. FIG. 2 is a schematic diagram showing a low dielectric resin film 1 to which catalyst nuclei 4 have been added after the plasma treatment of the present embodiment. 2 is a flowchart showing a method for manufacturing the copper clad laminate 10, the copper clad laminate 20, and the flexible circuit board of the present embodiment.

The copper clad laminate of this embodiment will be described below with reference to FIGS. 1 and 2. FIG.
<Copper-clad laminate>
As shown in Fig. 1, a copper clad laminate 10 according to this embodiment at least has a low dielectric resin film 1 serving as a base material, and an electroless copper plating layer 5 laminated on at least one surface of the low dielectric resin film 1. As shown in Fig. 2, a copper clad laminate 20 according to this embodiment may have an electrolytic copper plating layer 6 formed on the electroless copper plating layer 5.

In this embodiment, it is preferable to use a low dielectric resin film with excellent electrical properties in the high frequency range as the low dielectric resin film 1 serving as the substrate. Specifically, the electrical properties of the low dielectric resin film 1 serving as the substrate are preferably a relative dielectric constant of 3.5 or less at a frequency of 10 GHz and a dielectric loss tangent of 0.008 or less.

More specifically, known resin materials with low dielectric loss can be applied as the low dielectric resin film 1. More specifically, among the low dielectric resin films 1 suitable for this embodiment, examples of non-fluorine-based low dielectric resin films that do not contain fluorine and have a relative dielectric constant of less than 3.2 at a frequency of 10 GHz and a dielectric loss tangent of 0.008 or less include cycloolefin copolymer (COC), cycloolefin polymer (COP), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc. Examples of fluorine-containing fluorine-based low dielectric resin films include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), etc.
Furthermore, among the low dielectric resin films 1 suitable in this embodiment, examples of non-fluorine-based low dielectric resin films that do not contain fluorine and have a relative dielectric constant of 3.2 or more and a dielectric loss tangent of 0.008 or less at a frequency of 10 GHz include liquid crystal polymers (LCPs).

As the low dielectric resin film 1, in addition to the above, films of polyimide resin, modified polyimide resin, epoxy resin, polytetrafluoroethylene resin, polyphenylene ether resin, etc. may also be used.
The resins listed above may be monopolymers or copolymers, and may be used alone or as a composite of a blend of multiple resins.
The thickness of the low dielectric resin film 1 is not particularly limited, but is preferably 5 μm to 100 μm in practical use.

Furthermore, it is preferable that the average surface roughness Ra of the low dielectric resin film 1 at the interface with the electroless copper plating layer 5 is 1.0 nm to 100.0 nm. The average surface roughness Ra of the low dielectric resin film 1 at the interface with the electroless copper plating layer 5 is more preferably 1.0 nm to 70.0 nm, even more preferably 1.0 nm to 50 nm, and particularly preferably 1.0 nm to 30 nm. By controlling the average surface roughness Ra within the above range, it is possible to more suitably suppress transmission loss.

Next, the electroless copper plating layer 5 that is directly laminated on at least one surface of the low dielectric resin film 1 will be described.
Here, "direct lamination" refers to a lamination mode in which at least a part of the copper layer is in contact with the low dielectric resin film at the interface without the intervention of a known adhesive such as an epoxy resin or a urethane resin. That is, as shown in Fig. 1, the electroless copper plating layer 5 of this embodiment is in contact with the low dielectric resin film 1 at the interface, although the metal palladium Pd constituting the catalyst cores 4 described later is scattered at the interface. In other words, the electroless copper plating layer 5 of this embodiment is formed on the low dielectric resin film 1 without the intervention of an intermediate layer (the above-mentioned adhesive layer) other than the catalyst core layer.

[Interface state between low dielectric resin film and electroless copper plating layer]
Next, the interface state between the low dielectric resin film 1 and the electroless copper plating layer 5 in this embodiment will be described with reference to Fig. 3. This embodiment is mainly characterized in that, in order to increase the adhesive strength between the copper plating layer and the film, which are directly laminated, a plasma treatment is performed on the low dielectric resin film 1 before lamination to form functional groups 2, and in order to strengthen the adhesiveness of the catalyst cores 4 after the plasma treatment, a Pd-supported layer 3 is formed.

That is, as exemplified in the above-mentioned patent documents, in the past, when forming an electroless copper plating layer on a low dielectric resin film, surface modification was performed using alkaline hydrolysis (wet process). In this way, it was found that in the surface modification of a low dielectric resin film by a wet process, the cleavage of molecules present on the resin surface and the generation of functional groups are not necessarily good, and there is a risk that the palladium catalyst cannot be supported on the film surface afterwards. This means that the Pd complex (catalytic nucleus 4) that becomes the precipitation nucleus of the electroless copper plating layer 5 cannot be supported on the film surface, and if it remains as it is, the electroless copper plating layer 5 with high adhesion cannot be stably formed on the low dielectric resin film 1.
Based on such findings, the present disclosure has concluded that the surface of a low dielectric resin film is modified by a dry process using a vacuum plasma treatment as described below.

As mentioned above, in order to achieve good adhesion between the film and the copper plating layer, the process of cutting the molecules present on the film and generating functional groups is important. Therefore, in this embodiment, the vacuum plasma treatment described below is carried out as the first surface modification treatment (described in detail later), and a process of cutting the molecules and adding functional groups is carried out. Figure 4 shows the configuration of a vacuum plasma treatment apparatus 100 suitable for this embodiment.

The vacuum plasma processing apparatus 100 may be a known vacuum plasma processing apparatus equipped with a high-frequency power source 110, a pair of electrodes 120 with gas flow paths formed therein, a mounting table 130 on which the material to be processed (in this example, a low dielectric resin film) can be placed, a processing gas supply source 140 such as oxygen or argon, and a vacuum pump 150. The vacuum plasma processing apparatus 100 may further be equipped with a known magnetron mechanism capable of generating a magnetic field in any direction, such as that exemplified in JP 2001-23958 A.

In this manner, in the vacuum plasma processing apparatus 100, a plasma processing gas PG is supplied as an activation gas from a processing gas supply source 140 via an electrode 120 to the low dielectric resin film 1 fixed on a mounting table 130 in a vacuum chamber. This causes the molecules to be cut on the surface of the low dielectric resin film 1 and functional groups 2 to be imparted.

Here, the output condition in the vacuum plasma treatment of this embodiment is preferably 0.05 W/cm ² to 2.00 W/cm ^2. In addition, it is preferable to change the type of gas supplied from the treatment gas supply source 140 and the output condition according to the material of the low dielectric resin film 1.

More specifically, for example, when the low dielectric resin film 1 is a non-fluorinated resin (COC, COP, SPS, LCP, PPS, PEEK, etc.), it is preferable to use oxygen plasma as the plasma treatment gas PG from the viewpoint of breaking the bond energy (C-H bonds or C-C bonds, etc.) and modifying (hereinafter also referred to as "generating") functional groups (hydroxyl groups and/or carboxyl groups).

Also, for example, when the low dielectric resin film 1 is a fluororesin (such as the above-mentioned PTFE or PFA), it is necessary to cut the C-F bond, which has a high bond energy, so it is preferable to use argon plasma as the plasma treatment gas PG.

[Analysis of surface properties of low dielectric resin film after plasma treatment using XPS]
As described above, in this embodiment, the vacuum plasma treatment is performed according to the type of low dielectric resin film 1, whereby the cleavage of the molecules proceeds on the surface of the low dielectric resin film 1 and the functional groups 2 are imparted. In the present disclosure, the surface properties of the low dielectric resin film at this time are specified by the following method using the known XPS (X-ray photoelectron spectroscopy).

In other words, in this disclosure, while there are differences in the patterns of decomposition of the above molecules and generation of functional groups for each resin depending on the type of low dielectric resin film, the surface properties were identified using the results of XPS analysis, broadly categorizing them into non-fluorinated resins (COC, SPS, PPS, PEEK, etc.) and fluorinated resins (PFA, PTFE, etc.).

(α) Non-fluorinated resin (COC, SPS, PPS, PEEK, etc.)
5 illustrates the change in the XPS spectrum caused by the vacuum plasma treatment of the above-mentioned non-fluorinated resin (SPS as an example). In the present disclosure, the surface properties of the low dielectric resin film after the above-mentioned vacuum plasma treatment were specified by defining the area ratio of the peak derived from the C-C bond and the peak derived from the COO bond using the XPS spectrum before and after the plasma treatment of the non-fluorinated resin (COC, SPS, PPS, PEEK, etc.).

In FIG. 5, "FM1" indicates the low dielectric resin film before plasma treatment (in this disclosure, the low dielectric resin film before plasma treatment is also referred to as the "original film"), "FM2" indicates the low dielectric resin film after plasma treatment, "FM3" indicates a film in which an electroless copper plating layer 5 is formed on the low dielectric resin film after plasma treatment by the method described below and then the electroless copper plating layer is dissolved and removed, and "FM4" indicates the low dielectric resin film after the wet treatment described in the conventional method is performed.

As an example, in this disclosure, the surface properties are specified by specifying the area ratio of the peak derived from the C-C bond to the peak derived from the COO bond in FM1 and FM3, but they may also be specified by the area ratio of the peak derived from the C-C bond to the peak derived from the COO bond in FM1 and FM2.

In the present disclosure, the specific apparatus used for the XPS analysis was a PHI5000 VersaProbeII manufactured by ULVAC-PHI, Inc., and the above-mentioned area ratio was calculated in the following procedure.
First, as shown by (α) in Fig. 5, zero correction is performed at the positions of 282 eV and 295 eV to define the baseline, which makes it possible to efficiently identify the peaks of the above-mentioned functional groups and their ratios.

Then, as shown by (β) in Figure 5, the minimum intensity was subtracted from the maximum intensity to normalize the maximum intensity to a value of 1. This makes it possible to compare only the changes in the spectrum before and after vacuum plasma treatment.

Then, the area ratio AR is calculated using the XPS spectra of the low dielectric resin film 1 before and after the vacuum plasma treatment based on the following formula 1.

AR = (P _area2 ) / (P _area1 )... (Formula 1)
however,
P _area2 : peak area of 282.0 eV to 290.0 eV of the low dielectric resin film after vacuum plasma treatment in the peak obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS). P _area1 : peak area of the original sheet before vacuum plasma treatment analyzed under the same conditions as P _area1 .
The reason for setting the upper limit at 290.0 eV in the above is that the influence of aromatic rings and fluorine compounds that may appear in the range above 290 eV is to be excluded in order to more accurately measure the peaks of functional groups such as _OH groups, COOH groups, COOOH groups, _SO3H groups, SO2H groups, and SOH groups.

The inventors conducted extensive experiments and studies using various low dielectric resin films and found that a copper-clad laminate with the following characteristics can suppress transmission loss while ensuring high adhesion (3.5 N/cm or more in the tape peel test described below) at the interface with the electroless copper plating layer laminated directly on at least one side of the low dielectric film.

That is, one feature of the copper clad laminate of the present disclosure is that, in a peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of a low dielectric resin film (a non-fluorinated resin having a relative dielectric constant of less than 3.2 at a frequency of 10 GHz and a dielectric dissipation factor of 0.008 or less) that has undergone the above-mentioned first surface modification treatment, the area ratio (P _area2 /P area1 ₎ of the peak area (P _area2 ) at 282.0 eV to 290.0 eV of the low dielectric resin film to the peak area (P _area1 ) of an original sheet of the low dielectric resin film analyzed under the same conditions is 0.90 or more and 2.00 or less. From the viewpoint of further improving adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, the area ratio (P _area2 /P _area1 ) is more preferably 1.00 or more, even more preferably 1.05 or more, and particularly preferably 1.10 or more.

Furthermore, in the copper clad laminate of the present disclosure, in the case of a non-fluorine-based low dielectric resin film (such as a liquid crystal polymer (LCP)) that does not contain fluorine and has a relative dielectric constant of 3.2 or more and a dielectric dissipation factor of 0.008 or less at a frequency of 10 GHz, in order to ensure high adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, in the peak waveform described above, the area ratio (P _area2 /P _{area1 ) of the peak area (P area2 )} of the low dielectric resin film at 282.0 eV to the peak area (P _area1 ) of the original sheet of the low dielectric resin film analyzed under the same conditions is 1.25 or more and 2.00 or less. From the viewpoint of further improving adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, the area ratio (P _area2 /P _area1 ) is more preferably 1.35 or more, even more preferably 1.40 or more, and particularly preferably 1.45 or more.

(β) Fluorine-based resin (PTFE, PFA, etc.)
6 illustrates the change in the XPS spectrum of the above-mentioned fluororesin (PFA as an example) due to the vacuum plasma treatment. As can be understood from the figure, unlike non-fluororesins, the spectrum of the fluororesin changes significantly due to the C-F bond being cut by the plasma treatment. For this reason, in the present disclosure, the surface properties of the low dielectric resin film after the above-mentioned vacuum plasma treatment were specified without using the original film by defining the peak intensity ratio PIR between the peak derived from the C-F bond and other peaks using the spectrum of the fluororesin after the plasma treatment by XPS.

In FIG. 6, "FM1" indicates the low dielectric resin film (original roll) before plasma treatment, "FM2" indicates the low dielectric resin film after plasma treatment, "FM3" indicates the film obtained by forming an electroless copper plating layer 5 on the low dielectric resin film after plasma treatment by the method described below and then dissolving and removing the electroless copper plating layer, and "FM4" indicates the low dielectric resin film after undergoing the wet treatment described in the conventional method.

In addition, to identify the surface properties of the fluororesin, the above-mentioned ULVAC-PHI PHI PHI5000 VersaProbe II was used to calculate the peak intensity ratio (PIR) by XPS of the low dielectric resin film after plasma treatment, using the following procedure.

First, as shown by (α) in FIG. 6, zero correction is performed at the positions of 282.0 eV and 295.0 eV to define the baseline. This makes it possible to efficiently identify the peaks and their ratios of the above-mentioned functional groups, as in the case of non-fluorinated resins. The reason for correcting at "the positions of 282.0 eV and 295.0 eV" in setting the baseline described above is to set the range to include peaks from the carbon chain (284.8 eV) to the _CF3 group (294 eV) so that the bonds of carbon-based compounds can be detected in a relatively wide range.

Next, as shown by (β) in Figure 6, the minimum strength may be subtracted from the maximum strength to normalize the maximum strength to a numerical value of 1. However, since the fluororesin in the low dielectric resin film 1 is specified by the peak intensity ratio, normalization is not essential and may be omitted as appropriate.

Then, as shown by (γ) in Figure 6, the peak intensity ratio PIR is calculated using the XPS spectrum of the low dielectric resin film 1 after the vacuum plasma treatment based on the following formula 2.

PIR=(maximum intensity I _MAX2 from 283.0 to 288.0 eV)/(maximum intensity I _MAX1 from 290.0 to 295.0 eV) (Equation 2)
In formula 2, "maximum intensity I _MAX2 of 283.0 to 288.0 eV" identifies a functional group that is influenced by the main chain in the molecular structure within the film, and "maximum intensity I _MAX1 of 290.0 to 295.0 eV" identifies a functional group that appears with maximum intensity when part of the above molecular structure is decomposed by vacuum plasma treatment.

The inventors conducted extensive experiments and studies using various low dielectric resin films and found that a copper-clad laminate with the following characteristics can suppress transmission loss while ensuring high adhesion (3.5 N/cm or more in the tape peel test described below) at the interface with the electroless copper plating layer that is laminated directly on at least one side of the low dielectric resin film.

In other words, as can be seen from Figure 6, one of the characteristics of the copper clad laminate of the present disclosure is that it has at least a peak between 283.0 eV and 288.0 eV in the peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of a low dielectric resin film (a fluororesin having a relative dielectric constant of less than 3.2 at a frequency of 10 GHz and a dielectric dissipation factor of 0.008 or less) that has undergone the first surface modification treatment described above.

In addition, the fluororesin suitable for this embodiment preferably has an intensity ratio (I MAX2 /I MAX1 ) of the maximum peak intensity (I _MAX2 ) at 283.0 eV to 288.0 eV to the maximum peak intensity (I _MAX1 ) at 290.0 eV to 295.0 eV in the above _{-mentioned peak waveform of 1.00 or more. From the viewpoint of further improving adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, the intensity ratio (I MAX2 / I MAX1} ) is more preferably 2.00 or more, even more preferably 3.00 or more, and particularly preferably 4.00 or more.

In this manner, in the present disclosure, by subjecting the surface of the low dielectric resin film 1 to a vacuum plasma treatment, functional groups 2 (hydroxyl and/or carboxyl groups) are provided at the interface between the low dielectric resin film 1 and the electroless copper plating layer 5 (see FIG. 3). Note that the "functional group containing a hydroxyl and/or carboxyl group" provided at the interface between the low dielectric resin film 1 and the electroless copper plating layer 5 is not limited to this form. Furthermore, if a "functional group containing a hydroxyl group" is provided, a "functional group containing a carboxyl group" does not have to be provided. Also, the reverse may be true. Furthermore, both a "functional group containing a hydroxyl group" and a "functional group containing a carboxyl group" may be provided.
In order to specify the surface properties of the low dielectric resin film 1 after the plasma treatment, in this disclosure, the surface properties are specified by the above-mentioned method using a known XPS spectrum.

[Electroless copper plating layer]
1, the electroless copper plating layer 5 in this embodiment is preferably formed by a known electroless copper plating process. That is, since the low dielectric resin film 1 has insulating properties, a copper plating layer is formed on the film by the above-mentioned electroless copper plating process. This electroless copper plating layer 5 may be a seed layer when manufacturing a flexible circuit board by a semi-additive method (SAP method or MSAP method), a subtractive method, a full additive method, or the like.

In this embodiment, the electroless copper plating layer 5 may be a plating of Cu alone, or may be a copper alloy plating containing a predetermined amount or more of copper. Examples of copper alloys include Cu-Ni alloys, Cu-Zn alloys, and Cu-Sn alloys. In this embodiment, such copper alloy plating is also included in the "copper plating".
In this case, the Cu content in the electroless copper plating layer 5 is preferably 99.5 wt % or more, more preferably 99.6 wt % or more, and even more preferably 99.7 wt % or more.

Furthermore, when the electroless copper plating layer 5 is formed of a Cu-Ni alloy, the Ni content is 3 wt % or less, preferably 0.01 to 3 wt %, more preferably 0.01 to 1.5 wt %, and even more preferably 0.01 to 0.3 wt %.
When the electroless copper plating layer 5 is a Cu-Ni alloy, it is preferable to include Ni, which has a higher plating deposition rate than Cu, because this suppresses internal stress in the plating layer and therefore suppresses blistering.

If the Ni content in the Cu-Ni alloy exceeds 3 wt%, magnetism may occur in the Cu circuit, increasing transmission loss, and etching may become complicated when forming copper wiring, so the Ni content in the Cu-Ni alloy is preferably 3 wt% or less. If the Ni content in the Cu-Ni alloy falls below 0.01 wt%, plating deposition deteriorates.
The Ni content of the electroless copper plating layer 5 can be measured by known methods such as an X-ray fluorescence device (XRF) or an inductively coupled plasma (ICP) spectrometer.

In the present embodiment, a known plating bath may be used in the electroless copper plating step for forming the electroless copper plating layer 5 on the low dielectric resin film 1 as long as it is capable of forming the electroless copper plating layer 5 having a predetermined thickness. As an example, the electroless copper plating bath used in the present embodiment may be an EDTA bath, a Rochelle bath, a triethanolamine bath, or the like.
In addition, the thickness of the electroless copper plating layer 5 in this embodiment is preferably in the range of 50 nm to 1000 nm from the viewpoint of production efficiency and cost, more preferably 50 nm to 500 nm, and even more preferably 50 nm to 300 nm.

[Adhesion strength between low dielectric resin film and electroless copper plating layer]
Next, a method (one example) for evaluating the adhesion strength of the electroless copper plating layer 5 formed on the low dielectric resin film 1 using the above-mentioned method will be described. That is, in the embodiment, the following tape peel test is applied as the method for evaluating the above-mentioned adhesion strength.
This test conforms to the plating adhesion test method described in JIS H 8504 (1999) and is a known method for examining the adhesion of plating by attaching an adhesive tape to the plated surface and then rapidly and strongly peeling it off.

The test tape is an adhesive tape specified in JIS Z 1522, and may have a nominal width of 12 to 19 mm. The adhesive strength of this test tape is specified as approximately 8 N (i.e., 3.48 N/cm) per 25 mm width.
During the test, an electroless copper plating layer 5 is directly laminated on a low dielectric resin film 1 by the method of this embodiment, and then a test tape is attached to the electroless copper plating layer 5, and then this is quickly and strongly peeled off.

At this time, the surface of the electroless copper plating layer 5 to which the test tape is adhered is used as the test target surface, and if any plating remains on the adhesive surface of the peeled test tape, it is evaluated as having poor adhesion.
From the above-described results of the tape peeling test, it can be estimated that the adhesion strength between the low dielectric resin film 1 and the electroless copper plating layer 5 in this embodiment is 3.5 N/cm or more.

[others]
As shown in FIG. 2, this embodiment may be implemented as a copper clad laminate 20 in which an electrolytic copper plating layer 6 is further formed on the electroless copper plating layer 5. That is, for example, when a known flexible circuit board is manufactured by a semi-additive method, the electroless copper plating layer 5 may be used as a seed layer to form a resist pattern, and then an electrolytic copper plating layer 6 may be formed by a known method. As an example, a known copper sulfate bath or a copper pyrophosphate bath can be applied as an electrolytic copper plating step for forming the electrolytic copper plating layer 6. In addition, the electrolytic plating conditions (pH, temperature, current density, immersion time, etc.) can be appropriately selected based on the desired thickness of the electrolytic plating layer, etc.

In addition, the copper clad laminate 10 in this embodiment is formed by laminating the electroless copper plating layer 5 directly onto the low dielectric resin film 1 as described above, but for example, a known protective layer for preventing oxidation may be formed on the surface of the electroless copper plating layer 5. Similarly, in this embodiment, the copper clad laminate 20 may be formed by forming a known protective layer on the electrolytic copper plating layer 6 described above.

<Method of Manufacturing Copper Clad Laminate>
Next, a method for manufacturing the copper clad laminate 10 of this embodiment will be described with reference to FIG.
That is, first, in step 1, as a first surface modification process, a vacuum plasma treatment is performed on the above-mentioned low dielectric resin film 1. As an example, the above-mentioned vacuum plasma treatment apparatus 100 is used to supply a plasma treatment gas according to the material of the low dielectric resin film to the film surface. As a result, a part of the molecular structure on the surface of the low dielectric resin film 1 is decomposed, and the above-mentioned functional group 2 is imparted to the surface of the low dielectric resin film 1.

In the next step 2, a second surface modification process is performed by applying a positive charge to the surface of the low dielectric resin film 1, for example as a Pd-supported layer 3, and then subsequently applying a negative charge. By interposing such a Pd-supported layer 3 between the film and the electroless copper plating layer, it is possible to more reliably maintain the catalyst nuclei 4, which serve as the cores for plating deposition, on the film.

In the next step 3, a catalyst adsorption process is performed in which catalytic nuclei 4 are adsorbed onto the low dielectric resin film 1 on which the Pd support layer 3 has been formed. In the subsequent step 4, an electroless copper plating layer 5 is formed on the surface of the low dielectric resin film 1 on which the catalytic nuclei 4 have been adsorbed. As an example, the electroless copper plating layer 5 may be formed using a known plating bath such as an EDTA bath, a Rochelle bath, or a triethanolamine bath.

Through the above steps, a copper clad laminate 10 is produced, which includes a low dielectric resin film 1 having a relative dielectric constant of less than 3.2 at a frequency of 10 GHz and a dielectric loss tangent of 0.008 or less, and an electroless copper plating layer 5 directly laminated on at least one surface of the low dielectric resin film 1. In particular, when the low dielectric resin film 1 is made of a non-fluorinated resin, a copper clad laminate 10 is obtained in which, in a peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film 1, the area ratio (P area2 /P _{area1 ) of a peak area (P area2} ) from 282.0 eV to 290.0 eV of the low dielectric resin film 1 to a peak area (P _area1 ) of the original sheet of the low dielectric resin film ₁ analyzed under _{the same} conditions is 0.90 or more and 2.00 or less.
Furthermore, when the low dielectric resin film 1 is made of a fluororesin, a copper clad laminate 10 is obtained that has at least a peak at 283.0 eV to 288.0 eV in a peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film 1.

Furthermore, by undergoing the above steps, a copper-clad laminate 10 is obtained, which includes a fluorine-free, non-fluorine-based low dielectric resin film 1 (such as a liquid crystal polymer (LCP)) that does not contain fluorine and has a relative dielectric constant of 3.2 or more and a dielectric loss tangent of 0.008 or less at a frequency of 10 GHz, and an electroless copper plating layer 5 on at least one surface of the low dielectric resin film 1, and in a peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film 1, the area ratio (P _area2 /P _area1 ) of a peak area (P _area2 ) from 282.0 eV to 290.0 eV of the low dielectric resin film 1 to a peak area (P _area1 ) of an original sheet of the low dielectric resin film 1 analyzed under the same conditions is 1.25 or more and 2.00 or less.

In this embodiment, the process up to the formation of the electroless copper plating layer 5 in step 4 has been described. However, the present disclosure is not limited to the structure of the copper clad laminate 10 described above, and may subsequently include a heating (annealing) process for heating the copper clad laminate 10 on which the electroless copper plating layer 5 has been formed. Furthermore, after the heating (annealing) process for heating the copper clad laminate 10, the process may further include a resist patterning process for forming a resist on the electroless copper plating layer 5, an electrolytic copper plating process for forming an electrolytic copper plating layer 6 between the patterned resist, and a resist removal process for removing the patterned resist.

Thus, the method for producing a copper clad laminate in this embodiment is a method for producing a copper clad laminate by forming an electroless copper plating layer on a low dielectric resin film having a relative dielectric constant of 3.5 or less at a frequency of 10 GHz and a dielectric tangent of 0.008 or less, and is characterized by including at least a step of performing a first surface modification on the surface of the low dielectric resin film by vacuum plasma treatment, and an electroless copper plating step of directly laminating an electroless copper plating layer on the side of the low dielectric resin film that has been surface modified by the vacuum plasma treatment.
Each step will be described in detail below.

[Plasma treatment of low dielectric resin film: first surface modification step]
First, in the first surface modification step, a vacuum plasma treatment is performed on at least one surface of the low dielectric resin film 1 using a vacuum plasma treatment device 100 as illustrated in Fig. 4. The vacuum plasma treatment can be performed, for example, by preparing a low dielectric resin film 1, using the joining surface of the low dielectric resin film 1 as one electrode grounded to earth, and applying an alternating current of 1 MHz to 50 MHz between the joining surface and another electrode supported insulated to generate a glow discharge. During the vacuum plasma treatment, the earthed electrode takes the form of a cooling roll to prevent the temperature of the transported material from rising.

In the vacuum plasma treatment in the first surface modification step described above, the joining surface of the low dielectric resin film 1 is subjected to vacuum plasma treatment with a plasma treatment gas (active gas or inert gas) under vacuum, which cuts the molecules present on the low dielectric resin film 1 to generate functional groups, making it possible to achieve good adhesion between the low dielectric resin film 1 and the electroless copper plating layer 5. As the active gas, oxygen or a mixed gas containing oxygen can be used. As the inert gas, argon, neon, xenon, krypton, etc., or a mixed gas containing at least one of these can be used.

Here, the output condition in the vacuum plasma treatment of this embodiment is preferably 0.05 W/cm ² to 2.00 W/cm ^2. In addition, it is preferable to change the type of gas supplied from the treatment gas supply source 140 and the output condition according to the material of the low dielectric resin film 1.

More specifically, for example, when the low dielectric resin film 1 is a non-fluorine-based resin (COC, COP, SPS, LCP, PPS, PEEK, etc.), it is preferable to use oxygen as the plasma treatment gas from the viewpoint of breaking the bond energy (C-H bonds or C-C bonds, etc.) and generating functional groups (hydroxyl groups and/or carboxyl groups). In particular, when the low dielectric resin film 1 is a cycloolefin-based resin (COC, COP, etc. as described above), it is more preferable to perform oxygen plasma treatment with a relatively low output as the output condition of the plasma treatment gas, since not much energy is required to break the molecules described above. Also, when the low dielectric resin film 1 is a resin containing an aromatic ring (SPS, LCP, PPS, PEEK, etc. as described above), it is more preferable to perform oxygen plasma treatment with a relatively high output as the output condition of the plasma treatment gas, since relatively strong energy is required to break the molecules of the aromatic ring.

Furthermore, for example, when the low dielectric resin film 1 is a fluororesin (such as the above-mentioned PTFE or PFA), it is necessary to break the C-F bond, which has high bond energy, so it is preferable to use argon (Ar) as the plasma treatment gas.

It is preferable that the above-described vacuum plasma processing apparatus 100 further includes a magnetron mechanism capable of generating a magnetic field in any direction.
In the manufacturing method of the copper clad laminate in this embodiment, by installing a magnetron mechanism, it is possible to locally confine the plasma on the surface of the low dielectric resin film 1, and with a low output of the plasma treatment gas of 0.05 W/cm ² to 2.00 W/cm ² , it is possible to increase the adhesion between the low dielectric resin film 1 and the electroless copper plating layer 5 while suppressing thermal deformation of the low dielectric resin film 1 during plasma treatment (controlling the smoothness and flatness of the film surface).

When the magnetron mechanism described above is installed, the output condition of the plasma treatment gas is more preferably 0.05 W/cm ² to 1.50 W/cm ² , even more preferably 0.05 W/cm ² to 1.20 W/cm ² , and particularly preferably 0.10 W/cm ² to 1.20 W/cm ² . The treatment time of the plasma treatment gas is preferably 50 seconds to 1500 seconds, more preferably 50 seconds to 1350 seconds, and even more preferably 80 seconds to 1350 seconds. By controlling the time within the above range, the adhesion between the low dielectric resin film 1 and the electroless copper plating layer 5 and the surface smoothness of the low dielectric resin film 1 can be improved, which is preferable.
On the other hand, when the output conditions of the plasma treatment gas and the treatment time are below the lower limit of the above range, it is not preferable because sufficient adhesion between the low dielectric resin film 1 and the electroless copper plating layer 5 cannot be obtained. When the output conditions of the plasma treatment gas and the treatment time are above the upper limit of the above range, it is not preferable because the smoothness or flatness of the surface of the low dielectric resin film 1 may be impaired, resulting in an increased transmission loss.

[Charge application to low dielectric resin film after plasma treatment: second surface modification step]
After the low dielectric resin film 1 is subjected to the vacuum plasma treatment by the above-mentioned method, as shown in Fig. 3, a second surface modification step may be performed in which a Pd-supported layer 3 (positive and negative charges) is provided to the side of the low dielectric resin film 1 that has been subjected to the first surface modification treatment. By providing charges as the Pd-supported layer 3, it is possible to improve the adhesion of catalyst cores 4 (metallic palladium Pd in this example) to the film, which will be described later.

In other words, in order to form an electroless copper plating layer 5 on the low dielectric resin film 1, it is preferable that catalytic nuclei that serve as the cores for plating deposition are present on the film. From this perspective, in order for these catalytic nuclei (metallic palladium Pd) to adhere firmly to the film, it is preferable that the surface of the low dielectric resin film 1 has at least a negative charge after undergoing the second surface modification process.

Therefore, in the second surface modification process of this embodiment, it is preferable to apply a positive charge to the surface of the low dielectric resin film 1, and then apply a negative charge to the surface to which the positive charge has been applied. By going through these processes, it is possible to reliably attach a negative charge to the surface of the low dielectric resin film 1.

Specific methods for applying a positive charge to the surface of the low dielectric resin film 1 include, for example, immersing the film in a known cationic surfactant or spraying the cationic surfactant into contact with the low dielectric resin film 1.

In addition, specific methods for imparting a negative charge to the surface of the low dielectric resin film 1 include, for example, a method of immersing the film in a known anionic surfactant or a method of contacting the low dielectric resin film 1 with the anionic surfactant by spraying the film.
By the above-mentioned method, as shown in FIG. 3, a Pd-supported layer 3 is formed on the functional group 2 of the low dielectric resin film 1 that has been subjected to the vacuum plasma treatment.

[Addition of catalyst nuclei to low dielectric resin film: catalyst adsorption treatment]
Next, the catalyst adsorption treatment in this embodiment will be described. That is, the catalyst adsorption treatment in this embodiment is a process of adsorbing catalyst nuclei 4, which serve as nuclei for plating deposition in the electroless copper plating layer, onto the low dielectric resin film 1 having the surface charged by the above-mentioned second surface modification process, as exemplified in FIG. 7 .

More specifically, a method for adsorbing catalytic nuclei (metallic palladium Pd in this example) onto the surface of the low dielectric resin film 1 can be, for example, by contacting a known catalytic liquid with the surface of the low dielectric resin film 1 by a known method. Examples of such catalytic nuclei include, in addition to the above-mentioned metallic palladium Pd, Cu, Ni, Ag, etc. Also, as an example of the above-mentioned known catalytic liquid, a tin-palladium-based or palladium colloid-based catalytic liquid, etc. can be used.

In the above-mentioned catalyst adsorption treatment, the amount of catalyst applied to the low dielectric resin film 1 is preferably 30 μg/ ^dm2 or less in terms of metallic palladium. With regard to the lower limit of the catalyst, the less the better, taking into consideration the etching during circuit formation, but it is necessary to apply the catalyst to such an extent that an electroless copper plating layer is well formed, and the amount is preferably 5 μg/dm2 or ^more .
In the above-mentioned catalyst adsorption process, the low dielectric resin film may be immersed for several minutes in an aqueous solution (e.g., at 25°C) containing, as a catalyst activator (reducing agent), for example, 1 g/L of dimethylamine borane (DMAB) and 6 g/L of boric acid to perform a reduction treatment of the catalyst cores 4.

[Formation of electroless copper plating layer 5 on low dielectric resin film: electroless copper plating process]
Next, the electroless copper plating process of this embodiment will be described. That is, the electroless copper plating process of this embodiment is a process of forming an electroless copper plating layer on the surface of the low dielectric resin film 1 on which the above-mentioned catalytic nuclei 4 are adsorbed, using a known bath such as an EDTA bath, a Rochelle bath, or a triethanolamine bath as an electroless copper plating bath.

The immersion time of the low dielectric resin film 1 in the electroless copper plating bath may be appropriately determined so that the thickness of the electroless copper plating layer 5 becomes 50 nm to 1000 nm.
Furthermore, the plating layer formed in this electroless copper plating process is not limited to plating of simple Cu, but may be plating of a copper alloy, for example, a Cu-Ni alloy, a Cu-Zn alloy, a Cu-Sn alloy, etc.
By carrying out the above steps, the copper clad laminate 10 of this embodiment is manufactured.

The present invention will now be described more specifically with reference to examples.
Example 1
First, COC (Coxec TCS-1, Kurabo Industries, Ltd., thickness: 25 μm) was prepared as the low dielectric resin film 1. As for electrical properties, the relative dielectric constant at 10 GHz was 2.3, and the dielectric loss tangent at 10 GHz was 0.0013.

Next, as a first surface modification step, oxygen ( _O2 ) plasma treatment was performed on both sides of the prepared low dielectric resin film 1 by the above-mentioned vacuum plasma treatment device 100. The plasma treatment conditions were as follows: the vacuum plasma treatment device 100 was equipped with a magnetron mechanism, the output was 0.30 W/ ^cm2 , and the treatment time was 90 seconds.

Next, as the second surface modification process, both sides of the low dielectric resin film 1 were immersed in an aqueous solution of 10 g/L of a cationic surfactant for 2 minutes to adsorb positive charges. After immersion and rinsing with water, the film was immersed in an aqueous solution of 3 g/L of an anionic surfactant for 1 minute. In this way, positive charges were adsorbed, and then negative charges were adsorbed.

Next, as a catalyst adsorption step, the plate was immersed in an aqueous solution of palladium chloride ( _PdCl2 ) (2 g/L, pH 12, 40°C) as a plating catalyst for 5 minutes, followed by immersion and washing with water. Furthermore, the plate was immersed in an aqueous solution (25°C) containing 1 g/L of dimethylamine borane (DMAB) and 6 g/L of boric acid as a catalyst activator (reducing agent) for 5 minutes, followed by immersion and washing with water.

Then, in the electroless copper plating process, an electroless Cu-Ni plating layer was formed to a thickness of 200 nm using an electroless plating bath. The electroless plating conditions were as follows:

[Electroless plating conditions]
Bath composition: copper sulfate 7.5g/L
Sulfuric acid 0.6g/L
Nickel sulfate 0.006g/L
Rochelle salt 20g/L
IPA 0.5g/L
Sodium hydroxide 6.8g/L
Formaldehyde: 2.2g/L
pH: 12.5
Bath temperature: 45°C

In this example, a copper clad laminate 10 was manufactured in which an electroless copper plating layer 5 was formed on a low dielectric resin film 1 by the above-mentioned method. Note that the heating (annealing) treatment was omitted for the obtained copper clad laminate 10.

<Analysis of surface properties>
In this example, a film (corresponding to "FM3" in FIG. 5) was produced by dissolving the electroless copper plating layer 5 in the obtained copper clad laminate 10 with a known dissolving agent (e.g., a 30% nitric acid solution, etc.). The surface properties of the low dielectric resin film 1 after the plasma treatment of this film were analyzed using the above-mentioned XPS (X-ray polymer spectroscopy).

As a result, in this example, in the peak obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS), the peak area (P _area2 ) of low dielectric resin film 1 from 282.0 eV to 295.0 eV, as well as the peak area (P _area1 ) of the original sheet of low dielectric resin film 1 analyzed under the same conditions, were measured, and the area ratio (P _area2 /P _area1 ) between these was calculated to be 1.39.

<Tape peel strength>
A test tape (25 mm wide, manufactured by Nichiban Co., Ltd.) was applied to the surface of the electroless copper plating layer 5 of the copper clad laminate 10 on which the electroless copper plating layer 5 was formed, and the tape was then peeled off in accordance with the "plating adhesion test method" described in JIS H 8504 (1999) to carry out the tape peel test described above. The test tape is an adhesive tape specified in JIS Z 1522, and one with a nominal width of 12 to 19 mm can be used. The adhesive strength of this test tape is specified to be about 8 N (i.e., 3.48 N/cm) per 25 mm width.
If plating was confirmed to be adhering to the adhesive surface of the peeled test tape upon visual inspection after peeling, the adhesion was deemed poor and the evaluation result was given an X; if no plating was confirmed to be adhering, the evaluation result was given an ⊚ (estimated to be 3.5 N/cm or more); and if plating was only confirmed to be adhering partially (to a level that does not cause any problems in practical use), the evaluation result was given an ◯.

<Surface roughness Ra after removal of electroless copper plating layer 5>
The electroless copper plating layer 5 was peeled off from the obtained copper clad laminate 10 (electroless copper plating layer 5 thickness: 200 nm) using the same solvent as described above to expose the low dielectric resin film 1. The surface roughness (arithmetic mean roughness Ra) of the exposed low dielectric resin film 1 was measured with an atomic force microscope (Bruker Dimension Icon) at a viewing angle of 10 μm × 10 μm.

<Metal Content (wt%) in Electroless Copper Plating Layer 5>
The surface of the low dielectric resin film 1 was cut into a size of 20 mm × 20 mm, and the element concentration ratio in the depth direction was calculated in 10 nm increments in _SiO2 terms using an X-ray photoelectron spectroscopic analyzer (ULVAC-PHI, VersaProbe II, X-ray source: Al, analysis area: 100 μm), and the Cu concentration [Cu/(Cu+Ni)] in the metal elements (Cu, Ni) when the element concentration of Cu was maximum was calculated in weight percent.
The results summarized above are shown in Tables 1, 2 and 4, respectively.

Example 2
The same procedure as in Example 1 was carried out, except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: a magnetron mechanism was installed in the vacuum plasma treatment apparatus 100, the output was 0.09 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1 and 2, respectively.

Example 3
The same procedure as in Example 1 was carried out, except that the low dielectric resin film 1 was SPS (Oidys CN, manufactured by Kurabo Industries, Ltd., thickness: 50 μm) and the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment device 100 was equipped with a magnetron mechanism, the output was 0.60 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1, 2 and 4, respectively.

Example 4
The same procedure as in Example 3 was carried out except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, the output was 0.09 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1 and 2, respectively.

Example 5
The same procedure as in Example 1 was carried out, except that the low dielectric resin film 1 was PPS (TORELINA 3030, manufactured by Toray Industries, Inc., thickness: 50 μm) and the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment device 100 was equipped with a magnetron mechanism, the output was 0.60 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1, 2 and 4, respectively.

Example 6
The same procedure as in Example 5 was carried out except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, the output was 0.30 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1 and 2, respectively.

Example 7
The same procedure as in Example 1 was carried out, except that the low dielectric resin film 1 was PEEK (EXPEEK, manufactured by Kurabo Industries, Ltd., thickness: 50 μm) and the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment device 100 was equipped with a magnetron mechanism, the output was 0.60 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1, 2 and 4, respectively.

Example 8
The same procedure as in Example 7 was carried out, except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, the output was 0.09 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1 and 2, respectively.

<Example 9>
The same procedure as in Example 1 was carried out except that the low dielectric resin film 1 was LCP (Vecstar CTQ, manufactured by Kuraray Co., Ltd., thickness: 50 μm) and the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions in this example were that the vacuum plasma treatment apparatus 100 was not equipped with the magnetron mechanism described above, the output was 0.31 W/cm ² , and the treatment time was 1260 seconds.
The results summarized above are shown in Tables 1 and 2, respectively.

Example 10
The same procedure as in Example 9 was carried out except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment apparatus 100 was not equipped with the magnetron mechanism described above, the output was 0.09 W/cm ² , and the treatment time was 420 seconds, similar to Example 9.
The results summarized above are shown in Tables 1, 2 and 4, respectively.

Example 11
The same procedure as in Example 1 was carried out except that the low dielectric resin film 1 was PFA (Fluon+ EA-2000, manufactured by AGC Inc., thickness: 50 μm), argon (Ar) gas was used as the plasma treatment gas, and the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment device 100 was equipped with a magnetron mechanism, the output was 0.60 W/cm ² , and the treatment time was 90 seconds.

In this example, the electroless copper plating layer 5 of the obtained copper clad laminate 10 was dissolved using a known dissolving agent to produce a film (corresponding to "FM3" in Figure 6). The surface properties of the low dielectric resin film 1 after plasma treatment of this film were analyzed using the XPS (X-ray polymer spectroscopy) described above.

As a result, in this example, the low dielectric resin film after plasma treatment was analyzed by XPS without using the original sheet. Specifically, the peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) had at least a peak at 283.0 eV to 288.0 eV, and the peak maximum intensity (I _MAX2 ) at 283.0 eV to 288.0 eV and the peak maximum intensity (I _MAX1 ) at 290.0 eV to 295.0 eV were measured, and the peak intensity ratio (I _MAX2 /I _MAX1 ) was calculated to be "4.90".
The results are summarized in Tables 1, 3 and 4, respectively.

Example 12
The same procedure as in Example 11 was carried out, except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were that the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, the output was 0.15 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1 and 3, respectively.

Example 13
The same procedure as in Example 11 was carried out except that the low dielectric resin film 1 was made of PTFE (skived tape, manufactured by Chukoh Chemical Industries, Ltd., thickness: 50 μm). Specific plasma treatment conditions were as follows: the vacuum plasma treatment device 100 was equipped with a magnetron mechanism, the output was 0.60 W/cm ² , and the treatment time was 90 seconds.
The results are summarized in Tables 1, 3 and 4, respectively.

<Example 14>
The same procedure as in Example 13 was carried out except that the plasma treatment conditions were as shown in Table 1. Specifically, the plasma treatment conditions were as follows: the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, the output was 0.15 W/cm ² , and the treatment time was 90 seconds.
The results summarized above are shown in Tables 1 and 3, respectively.

<Comparative Example 1>
The first surface modification treatment was carried out in the same manner as in Example 1, except that the known wet treatment shown in Patent Documents 3 to 6 was carried out instead of the vacuum plasma treatment. The wet treatment involved immersion in a mixed solution of potassium hydroxide aqueous solution and monoethanolamine for 5 minutes to introduce carboxyl groups and/or hydroxyl groups to both surfaces, followed by immersion washing with water. The temperature of the mixed solution used was 45°C.
The results are summarized in Tables 1 and 2.

<Comparative Example 2>
The same procedure as in Comparative Example 1 was carried out except that the low dielectric resin film 1 was an SPS (Oidys CN, manufactured by Kurabo Industries, Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 3>
The same procedure as in Comparative Example 1 was carried out except that the low dielectric resin film 1 was made of PPS (TORELINA 3030, manufactured by Toray Industries, Inc., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 4>
The same procedure as in Comparative Example 1 was carried out except that the low dielectric resin film 1 was made of PEEK (EXPEEK, manufactured by Kurabo Industries, Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 5>
The same procedure as in Comparative Example 1 was carried out except that the low dielectric resin film 1 was an LCP (Vecstar CTQ, manufactured by Kuraray Co., Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 6>
The first surface modification treatment was carried out in the same manner as in Example 11, except that the known wet treatments shown in Patent Documents 3 to 6 were carried out instead of the vacuum plasma treatment. Note that the wet treatment was the same as in Comparative Example 1.
The results are summarized in Tables 1 and 3.

<Comparative Example 7>
The same procedure as in Comparative Example 6 was carried out except that the low dielectric resin film 1 was made of PTFE (skived tape, manufactured by Chukoh Chemical Industries, Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 3.

<Comparative Example 8>
The same procedure as in Comparative Example 1 was carried out, except that a heating (annealing) treatment was further carried out after the electroless copper plating layer 5 was formed.
The results are summarized in Tables 1 and 2.

<Comparative Example 9>
The same procedure as in Comparative Example 8 was carried out except that the low dielectric resin film 1 was an SPS (Oidys CN, manufactured by Kurabo Industries, Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 10>
The same procedure as in Comparative Example 8 was carried out except that the low dielectric resin film 1 was made of PPS (TORELINA 3030, manufactured by Toray Industries, Inc., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 11>
The same procedure as in Comparative Example 8 was carried out except that the low dielectric resin film 1 was made of PEEK (EXPEEK, manufactured by Kurabo Industries, Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 2.

<Comparative Example 12>
The same procedure as in Comparative Example 6 was carried out except that a heating (annealing) treatment was further carried out after the electroless copper plating layer 5 was formed.
The results are summarized in Tables 1 and 3.

<Comparative Example 13>
The same procedure as in Comparative Example 12 was carried out except that the low dielectric resin film 1 was made of PTFE (skived tape, manufactured by Chukoh Chemical Industries, Ltd., thickness: 50 μm).
The results are summarized in Tables 1 and 3.

 

 

 

 

The copper clad laminate of the present invention can ensure high adhesion at the interface between the low dielectric film and the electroless copper plating layer while suppressing transmission loss. Therefore, it is clear that the copper clad laminate of the present invention is suitable for use in wiring boards and the like that require multilayer fine wiring.

REFERENCE SIGNS LIST 1 Low dielectric resin film 2 Functional group 3 Pd-supported layer 4 Catalyst core 5 Electroless copper plating layer 6 Electrolytic copper plating layer 10, 20 Copper-clad laminate

Claims (17)

a low dielectric resin film having a relative dielectric constant of less than 3.2 and a dielectric tangent of 0.008 or less at a frequency of 10 GHz;
an electroless copper plating layer directly laminated on at least one surface of the low dielectric resin film;
A copper clad laminate comprising: A low dielectric resin film having a relative dielectric constant of 3.2 or more and a dielectric loss tangent of 0.008 or less at a frequency of 10 GHz, and an electroless copper plating layer on at least one surface of the low dielectric resin film,
A copper-clad laminate characterized in that, in a peak waveform obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film, an area ratio (P _area2 /P _{area1 )} of a peak area (P area2 ) of the low dielectric resin film from 282.0 eV to 290.0 eV of the low dielectric resin film to a peak area (P _area1 ) of an original sheet of the low dielectric resin film analyzed under the same conditions is 1.25 or more and 2.00 or less. 2. The copper clad laminate according to claim 1, wherein in peaks obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film, the area ratio (P _area2 /P area1 ₎ of a peak area (P _area2 ) of the low dielectric resin film at 282.0 eV to 290.0 eV of the low dielectric resin film to a peak area (P _area1 ) of an original sheet of the low dielectric resin film analyzed under the same conditions is 0.9 or more. The copper clad laminate of claim 1, wherein the surface of the low dielectric resin film has at least a peak at 283.0 eV to 288.0 eV in the peaks obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS). 5. The copper clad laminate according to claim 4, wherein the intensity ratio (I _MAX2 /I _{MAX1 ) of the peak maximum intensity (I MAX2 )} at 283.0 eV to 288.0 eV to the peak maximum intensity (I _MAX1 ) at 290.0 eV to 295.0 eV in the peak waveform is 1.00 or more. The copper clad laminate according to any one of claims 1 to 5, wherein the average surface roughness Ra of the low dielectric resin film at the interface with the electroless copper plating layer is 1.0 nm to 100.0 nm. The copper clad laminate according to any one of claims 1 to 5, wherein the adhesion strength between the low dielectric resin film and the electroless copper plating layer is 3.5 N/cm or more. The copper clad laminate according to any one of claims 1 to 5, wherein the thickness of the electroless copper plating layer is 50 nm to 1000 nm. The copper clad laminate according to any one of claims 1 to 5, wherein the Cu content in the electroless copper plating layer is 99.5 wt% or more. A method for producing a copper clad laminate, comprising forming an electroless copper plating layer on a low dielectric resin film having a relative dielectric constant of 3.5 or less and a dielectric loss tangent of 0.008 or less at a frequency of 10 GHz,
A step of performing a first surface modification treatment on the surface of the low dielectric resin film by a vacuum plasma treatment;
an electroless copper plating step of directly laminating an electroless copper plating layer on the surface of the low dielectric resin film that has been surface-modified by the vacuum plasma treatment;
A method for producing a copper clad laminate, comprising: The method further includes a second surface modification step of applying an electric charge to the first surface modified side of the low dielectric resin film, and a catalyst adsorption step of adsorbing a catalyst nucleus to the surface to which the electric charge is applied,
The method for producing a copper clad laminate according to claim 10 , wherein the electroless copper plating layer is formed on the surface on which the catalytic nuclei are adsorbed. The method for producing a copper clad laminate according to claim 11, wherein the first surface modification step includes a step of providing a carboxyl group and/or a hydroxyl group to the surface of the low dielectric resin film. The method for producing a copper clad laminate according to claim 12, wherein the low dielectric resin film is made of a resin that does not contain fluorine. The method for producing a copper clad laminate according to claim 13, wherein the vacuum plasma treatment is performed using oxygen as an activation gas. The method for manufacturing a copper clad laminate according to claim 12, wherein the low dielectric resin film is made of a resin containing fluorine. The method for producing a copper clad laminate according to claim 15, wherein the vacuum plasma treatment is performed using argon as an activation gas. The method for producing a copper clad laminate according to any one of claims 10 to 16, wherein the output condition in the vacuum plasma treatment is 0.05 W/cm ² to 2.00 W/cm ² .