Copper-clad laminate and method for producing same

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 manufacturing the same

[0001] The present invention relates to a copper clad laminate for a flexible circuit board mounted on a communication device or the like, a method for producing the same, and a flexible circuit board made from the copper clad laminate.

[0002] In recent years, electronic devices have become significantly smaller and more powerful, largely due to the development of communication devices that use radio waves, such as mobile phones and wireless LANs. In particular, with the recent increase in the volume of information, typified by big data generated by the IoT, communication signals between electronic devices are becoming increasingly high-frequency, and circuit boards mounted on such communication devices require materials with low transmission loss (dielectric loss) in the high-frequency range.

[0003] 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 loss tangent." Therefore, to obtain the above-mentioned excellent dielectric properties, a material with as low a dielectric constant and dielectric loss tangent as possible is necessarily required.

[0004] In such circuit boards, the circuits are generally formed of a metal such as copper, and the copper layer in the circuit board is formed by, for example, a lamination method as disclosed in Patent Document 1, a casting method as disclosed in Patent Document 2, or a plating method as disclosed in Patent Document 3.

[0005] Japanese Patent No. 6202905 Japanese Patent No. 5186266 JP 2002-256443 A International Publication No. 2021 / 039370 International Publication No. 2022 / 030644 International Publication No. 2022 / 030645

[0006] As mentioned above, reducing transmission loss in high-frequency communications has become an important development factor in recent years, and resin films with low transmission loss (hereinafter also referred to as "low-dielectric films" or "low-dielectric resin films") are increasingly being used as the base material for flexible circuit boards. Such flexible circuit boards (hereinafter also referred to as "FPCs") are manufactured by forming a conductive coating of copper or the like on a low-dielectric film using, for example, a sputtering method or a plating method. When FPCs are manufactured using the sputtering method, the manufacturing process becomes complicated, leaving many issues unresolved in terms of productivity and cost.

[0007] In contrast, the plating methods disclosed in Patent Documents 3 to 6, etc., can ensure relatively good adhesion between a copper layer and a resin film with a high dielectric constant. However, these patent documents also involve a surface modification step in which a mixed solution of an alkaline aqueous solution and an amino alcohol is applied to the surface of the resin film. After further investigation, the inventors have concluded that such surface modification by wet processing alone does not necessarily result in sufficient cleavage of molecules present on the resin film surface or generation of functional groups, and that in some cases, a catalyst, which serves as a deposition nucleus for subsequent electroless Cu plating, cannot be supported on the film surface.

[0008] The present invention aims to solve the above-mentioned problems as an example, and aims to provide a copper-clad laminate and a method for manufacturing the same that can achieve high adhesion between a low dielectric resin film and an electroless copper plating layer while suppressing transmission loss.

[0009] In order to solve the above-mentioned problems, a 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 dissipation factor of 0.008 or less, and an electroless copper plating layer laminated directly on at least one surface of the low dielectric resin film.

[0010] 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 the copper clad laminate has a peak area (P) of 282.0 eV to 290.0 eV of the low dielectric resin film 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. ａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) area ratio (P ａｒｅａ２ / P ａｒｅａ１ ) may be 1.25 or more and 2.00 or less.

[0011] Furthermore, in order to solve the above-mentioned problems, a method for manufacturing a copper clad laminate in one embodiment of the present invention is (10) a method for manufacturing a copper clad laminate produced 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 dissipation factor 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 side of the low dielectric resin film that has been surface modified by the vacuum plasma treatment.

[0012] According to the present invention, high adhesion can be ensured at the interface between the low dielectric film and the electroless copper plating layer while suppressing transmission loss.

[0013] 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) according to the present embodiment; FIG. 2 is a schematic diagram showing a copper clad laminate 20 (a low dielectric resin film 1 having an electrolytic copper plating layer 6 and an electroless copper plating layer 5 formed thereon) according to the present embodiment; FIG. 3 is a schematic diagram showing the interface state between the low dielectric resin film 1 and the electroless copper plating layer 5 in the copper clad laminate 10 according to the present embodiment; FIG. 4 is a schematic diagram showing the configuration of a vacuum plasma processing apparatus 100 according to the present embodiment; FIG. 5 is a schematic diagram showing XPS spectral changes due to vacuum plasma processing of SPS; FIG. 6 is a schematic diagram showing XPS spectral changes due to vacuum plasma processing of PFA; FIG. 7 is a schematic diagram showing a low dielectric resin film 1 to which catalyst cores 4 have been applied after undergoing plasma processing according to the present embodiment; and FIG. 8 is a flowchart showing methods for manufacturing the copper clad laminate 10, copper clad laminate 20, and flexible circuit board according to the present embodiment.

[0014] The copper clad laminate of this embodiment will be described below with reference to Figures 1 and 2. <Copper clad laminate> As shown in Figure 1, a copper clad laminate 10 of this embodiment has at least a low dielectric resin film 1 serving as a substrate, and an electroless copper plating layer 5 laminated on at least one surface of the low dielectric resin film 1. Furthermore, as shown in Figure 2, a copper clad laminate 20 of this embodiment may have an electrolytic copper plating layer 6 formed on the above-mentioned electroless copper plating layer 5.

[0015] In this embodiment, a low dielectric resin film having excellent electrical properties in the high frequency range is preferably used 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.

[0016] More specifically, known resin materials with low dielectric loss can be used as the low dielectric resin film 1. More specifically, among the low dielectric resin films 1 suitable for this embodiment, examples of fluorine-free, non-fluorine-based low dielectric resin films having a dielectric constant of less than 3.2 and a dielectric dissipation factor of 0.008 or less at a frequency of 10 GHz include cycloolefin copolymer (COC), cycloolefin polymer (COP), syndiotactic polystyrene (SPS), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). Examples of fluorine-containing, fluorine-based low dielectric resin films include polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA). Furthermore, among the low dielectric resin films 1 suitable for this embodiment, examples of fluorine-free, non-fluorine-based low dielectric resin films having a dielectric constant of 3.2 or more and a dielectric dissipation factor of 0.008 or less at a frequency of 10 GHz include liquid crystal polymer (LCP).

[0017] In addition to the above, films of polyimide resin, modified polyimide resin, epoxy resin, polytetrafluoroethylene resin, polyphenylene ether resin, etc. may also be used as the low dielectric resin film 1. The resins listed above may be monopolymers or copolymers. Furthermore, the resins may be used alone or as a composite obtained by blending multiple resins. Furthermore, there are no particular restrictions on the thickness of the low dielectric resin film 1, but in practice, a thickness of 5 μm to 100 μm is preferable.

[0018] The average surface roughness Ra of the low dielectric resin film 1 at the interface with the electroless copper plating layer 5 is preferably 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, transmission loss can be more suitably suppressed.

[0019] Next, the electroless copper plating layer 5 laminated directly 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 portion of the copper layer contacts the low dielectric resin film at the interface without the use of a known adhesive such as an epoxy resin or a urethane resin. That is, as shown in FIG. 1 and other figures, the electroless copper plating layer 5 of this embodiment is in contact with the low dielectric resin film 1 at the interface, although metallic palladium Pd constituting the catalyst nuclei 4 described below 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 an intermediate layer (the adhesive layer described above) other than the catalyst nuclei layer.

[0020] [Interfacial State Between Low Dielectric Resin Film and Electroless Copper Plating Layer] Next, the interfacial 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 film and the copper plating layer that is directly laminated thereon, the low dielectric resin film 1 is subjected to plasma treatment before lamination to form functional groups 2, and a Pd-supported layer 3 is formed to strengthen the adhesiveness of the catalyst nuclei 4 after the plasma treatment.

[0021] Specifically, as exemplified in the above-mentioned patent documents, conventionally, when forming an electroless copper plating layer on a low-dielectric resin film, surface modification using alkaline hydrolysis (wet process) has been performed. It has been found that surface modification of a low-dielectric resin film using this wet process does not necessarily result in satisfactory cleavage of molecules present on the resin surface and generation of functional groups, which may result in the subsequent inability to support a palladium catalyst on the film surface. This means that the Pd complex (catalytic nuclei 4), which serve as the precipitation nuclei for the electroless copper plating layer 5, cannot be supported on the film surface, and as is, a highly adhesive electroless copper plating layer 5 cannot be stably formed on the low-dielectric resin film 1. Based on this knowledge, the present disclosure has concluded that the surface modification of a low-dielectric resin film is performed using a dry process using vacuum plasma treatment, as described below.

[0022] As described above, the process of cleaving molecules present on the film to generate functional groups is important for achieving good adhesion between the film and the copper plating layer. Therefore, in this embodiment, the first surface modification treatment (described in detail later) involves the vacuum plasma treatment described below, which cleaves the molecules and adds functional groups. Figure 4 shows the configuration of a vacuum plasma treatment apparatus 100 suitable for this embodiment.

[0023] The vacuum plasma processing apparatus 100 may be a known vacuum plasma processing apparatus equipped with a high-frequency power supply 110, a pair of electrodes 120 formed with gas flow paths, a mounting table 130 on which a 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, as exemplified, for example, in Japanese Patent Application Laid-Open No. 2001-23958.

[0024] 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. As a result, the cleavage of the molecules on the surface of the low dielectric resin film 1 progresses and functional groups 2 are imparted.

[0025] Here, the output condition in the vacuum plasma treatment of this embodiment is 0.05 W / cm ２ ~2.00 W / cm ２ It is also preferable to change the type of gas supplied from the processing gas supply source 140 and the output conditions depending on the material of the low dielectric resin film 1 .

[0026] 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 plasma as the plasma treatment gas PG from the viewpoint of cleaving bond energy (C-H bonds, C-C bonds, etc.) and modifying (hereinafter also referred to as "generating") functional groups (hydroxyl groups and / or carboxyl groups).

[0027] Furthermore, for example, when the low dielectric resin film 1 is a fluorine-based resin (such as the above-mentioned PTFE or PFA), it is necessary to cut the C—F bond, which has high bond energy, and therefore it is preferable to use argon plasma as the plasma treatment gas PG.

[0028] [Analysis of Surface Properties of Low Dielectric Resin Film After Plasma Treatment Using XPS] As described above, in this embodiment, vacuum plasma treatment is performed depending on the type of low dielectric resin film 1, which causes the cleavage of the molecules on the surface of the low dielectric resin film 1 to proceed and provides functional groups 2. In the present disclosure, the surface properties of the low dielectric resin film at this time were identified by the following method using known XPS (X-ray photoelectron spectroscopy).

[0029] That is, in the present disclosure, although there are differences in the patterns of decomposition of the 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 by broadly classifying the resins into non-fluorinated resins (COC, SPS, PPS, PEEK, etc.) and fluorinated resins (PFA, PTFE, etc.).

[0030] (α) Non-fluorinated resin (COC, SPS, PPS, PEEK, etc.) Figure 5 shows an example of the change in the XPS spectrum of the above-mentioned non-fluorinated resin (SPS as an example) due to vacuum plasma treatment. 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 C-C bonds to the peak derived from CO-O bonds using the XPS spectra of the non-fluorinated resin (COC, SPS, PPS, PEEK, etc.) before and after plasma treatment.

[0031] In FIG. 5 , "FM1" indicates the low dielectric resin film before plasma treatment (in the present disclosure, the low dielectric resin film before plasma treatment is also referred to as the "raw sheet"), "FM2" indicates the low dielectric resin film after plasma treatment, "FM3" indicates a 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.

[0032] As an example, in the present disclosure, the surface properties are specified by defining the area ratio between the peak derived from the C—C bond and the peak derived from the COO bond in FM1 and FM3, but the surface properties may also be defined by the area ratio between the peak derived from the C—C bond and the peak derived from the COO bond in FM1 and FM2.

[0033] In this disclosure, the specific apparatus used for XPS analysis was a PHI5000 VersaProbe II manufactured by ULVAC-PHI, Inc., and the above-mentioned area ratios were calculated using the following procedure. First, as shown by (α) in Figure 5, zero correction was performed at positions 282 eV and 295 eV to define the baseline. This makes it possible to efficiently identify the peaks of the above-mentioned functional groups and their ratios.

[0034] Next, 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 spectra before and after vacuum plasma treatment.

[0035] Next, the area ratio AR is calculated based on the following formula 1 using the XPS spectra of the low dielectric resin film 1 before and after the vacuum plasma treatment.

[0036] AR = (P ａｒｅａ２ ) / (P ａｒｅａ１ ) ... (Equation 1) where P ａｒｅａ２ : The peak area P of the low dielectric resin film after vacuum plasma treatment at 282.0 eV to 290.0 eV in the peak obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) ａｒｅａ１ :P ａｒｅａ１ The upper limit is set to 290.0 eV because the peak area of ​​the raw sheet before vacuum plasma treatment is the same as that of the OH group, COOH group, COOOH group, and SO ３ H group, SO ２ In order to measure the peaks of functional groups such as H groups and SOH groups more accurately, the influence of aromatic rings and fluorine compounds that may appear in the range above 290 eV is eliminated.

[0037] The inventors conducted extensive experiments and studies using various low dielectric resin films and found that a copper clad laminate having 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.

[0038] That is, the copper clad laminate of the present disclosure has a peak area (P) of 282.0 eV to 290.0 eV of the low dielectric resin film 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 (a non-fluorinated resin 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) that has been subjected to the first surface modification treatment. ａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) area ratio (P ａｒｅａ２ / P ａｒｅａ１ ) is 0.90 or more and 2.00 or less. From the viewpoint of further improving the adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, it is one of the features of the present invention that 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.

[0039] Furthermore, in the copper clad laminate of the present disclosure, in the case where the low dielectric resin film that has undergone the first surface modification treatment is 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 at a frequency of 10 GHz and a dielectric loss tangent of 0.008 or less, in order to ensure high adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, the peak area (P ａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) area ratio (P ａｒｅａ２ / P ａｒｅａ１) is 1.25 or more and 2.00 or less. From the viewpoint of further improving the 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.

[0040] (β) Fluorine-Based Resin (PTFE, PFA, etc.) Figure 6 illustrates the change in the XPS spectrum of the above-mentioned fluorine-based resin (PFA as an example) due to vacuum plasma treatment. As can be seen from the figure, unlike non-fluorine-based resins, the C-F bonds of fluorine-based resins are cleaved by plasma treatment, resulting in a significant change in the spectrum. For this reason, in the present disclosure, the surface properties of the low dielectric resin film after the above-mentioned vacuum plasma treatment were identified without using the original film by defining the peak intensity ratio PIR (Peak Intensity Ratio) of the peak derived from the C-F bond to other peaks using the XPS spectrum of the fluorine-based resin after plasma treatment.

[0041] In FIG. 6, "FM1" indicates the low dielectric resin film (raw sheet) before the plasma treatment, "FM2" indicates the low dielectric resin film after the plasma treatment, "FM3" indicates a film obtained by forming an electroless copper plating layer 5 on the low dielectric resin film after the 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 the wet treatment described in the conventional method has been performed.

[0042] In addition, the surface properties of the fluororesin were also specified using the above-mentioned PHI5000 VersaProbe II manufactured by ULVAC-PHI, Inc., and the peak intensity ratio PIR by XPS of the low dielectric resin film after plasma treatment was calculated according to the following procedure.

[0043] 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 proportions 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 is that the peaks from the carbon chain (284.8 eV) to CF are corrected so that the bonds of carbon-based compounds can be detected in a relatively wide range. ３ This is to ensure that the range includes peaks up to the group (294 eV).

[0044] 6, the minimum intensity may be subtracted from the maximum intensity to normalize the maximum intensity so that the numerical value of the maximum intensity becomes 1. However, since the fluorine-based resin in the low dielectric resin film 1 is specified by the peak intensity ratio, normalization is not essential and may be omitted as appropriate.

[0045] Next, as shown by (γ) in FIG. 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 equation 2.

[0046] PIR = (maximum intensity I between 283.0 and 288.0 eV) ＭＡＸ２ ) / (Maximum intensity I from 290.0 to 295.0 eV ＭＡＸ１ ) ... (Equation 2) In Equation 2, "maximum intensity I ＭＡＸ２ " identifies functional groups that are affected by the main chain in the molecular structure of the film, and "maximum intensity I of 290.0 to 295.0 eV ＭＡＸ１ " identifies the functional groups that appear with the greatest intensity when a portion of the molecular structure is decomposed by vacuum plasma treatment.

[0047] The inventors have conducted extensive experiments and studies using various low dielectric resin films and have found that a copper clad laminate having 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 surface of the low dielectric resin film.

[0048] That is, as can be seen from FIG. 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.

[0049] In addition, the fluorine-based resin suitable for this embodiment is one having a peak maximum intensity (I ＭＡＸ２ ) and the peak maximum intensity between 290.0 eV and 295.0 eV (I ＭＡＸ１ ) and the intensity ratio (I ＭＡＸ２ / I ＭＡＸ１ From the viewpoint of further enhancing the adhesion at the interface between the low dielectric resin film and the electroless copper plating layer, it is preferable that the strength 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.

[0050] In this manner, in the present disclosure, by subjecting the surface of the low dielectric resin film 1 to vacuum plasma treatment, functional groups 2 (hydroxyl groups and / or carboxyl groups) are imparted to the interface between the low dielectric resin film 1 and the electroless copper plating layer 5 (see FIG. 3 ). Note that the "functional groups containing hydroxyl groups and / or carboxyl groups" imparted to the interface between the low dielectric resin film 1 and the electroless copper plating layer 5 are not limited to this form. Furthermore, as long as a "functional group containing a hydroxyl group" is imparted, a "functional group containing a carboxyl group" need not be imparted. The reverse is also possible. Furthermore, both a "functional group containing a hydroxyl group" and a "functional group containing a carboxyl group" may be imparted. In order to identify the surface properties of the low dielectric resin film 1 after plasma treatment, in the present disclosure, the properties are specified by the above-mentioned method using a known XPS spectrum.

[0051] 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-described electroless copper plating process. Note that this electroless copper plating layer 5 may also serve as a seed layer when manufacturing a flexible circuit board by a semi-additive process (SAP process or MSAP process), a subtractive process, a full-additive process, or the like.

[0052] In this embodiment, the electroless copper plating layer 5 may be a plating of Cu alone, or 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 considered to be 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.

[0053] 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 formed of a Cu—Ni alloy, the inclusion of Ni, which has a higher plating deposition rate than Cu, is preferable because it is believed that the internal stress in the plating layer is suppressed and therefore blisters are suppressed.

[0054] Note that if the Ni content in the Cu—Ni alloy exceeds 3 wt%, magnetism may occur in the Cu circuit, increasing transmission loss and complicating etching during copper wiring formation. Therefore, the Ni content in the Cu—Ni alloy is preferably 3 wt% or less. Furthermore, if the Ni content in the Cu—Ni alloy falls below 0.01 wt%, plating deposition properties deteriorate. The Ni content of the electroless copper plating layer 5 can be measured using known techniques such as an X-ray fluorescence analyzer (XRF) or an inductively coupled plasma (ICP) analyzer.

[0055] In the present embodiment, the electroless copper plating step for forming the electroless copper plated layer 5 on the low dielectric resin film 1 may use any known plating bath as long as it can form an electroless copper plated 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, or a triethanolamine bath. From the viewpoints of production efficiency and cost, the thickness of the electroless copper plated layer 5 in the present embodiment is preferably in the range of 50 nm to 1000 nm, more preferably 50 nm to 500 nm, and even more preferably 50 nm to 300 nm.

[0056] [Adhesion Strength Between Low Dielectric Resin Film and Electroless Copper Plated Layer] Next, a method (one example) for evaluating the adhesion strength of the electroless copper plated layer 5 formed on the low dielectric resin film 1 using the above-mentioned method will be described. That is, in this embodiment, the following tape peeling test is applied as a method for evaluating the above-mentioned adhesion strength. Note that this test conforms to the plating adhesion test method described in JIS H 8504 (1999), and is a known method for examining plating adhesion by applying adhesive tape to the plated surface and then rapidly and forcefully peeling it off.

[0057] The test tape is an adhesive tape specified in JIS Z 1522, and can be one with 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, after the electroless copper plating layer 5 is directly laminated on the low dielectric resin film 1 by the method of this embodiment, the test tape is attached to the electroless copper plating layer 5 and then quickly and forcefully peeled off.

[0058] The surface of the electroless copper plating layer 5 to which the test tape is adhered is the surface to be tested, and any plating remaining on the adhesive surface of the peeled test tape is evaluated as poor adhesion. From the test results using tape peeling described above, the adhesion strength between the low dielectric resin film 1 and the electroless copper plating layer 5 in this embodiment can be estimated to be 3.5 N / cm or more.

[0059] [Others] This embodiment may be implemented as a copper clad laminate 20 in which an electrolytic copper plating layer 6 is further formed on the above-described electroless copper plating layer 5, as shown in FIG. 2 . That is, for example, when a known flexible circuit board is manufactured by a semi-additive process, the above-described 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 copper pyrophosphate bath can be used as the electrolytic copper plating step for forming the electrolytic copper plating layer 6. Furthermore, the electrolytic plating conditions (e.g., pH, temperature, current density, immersion time) can be appropriately selected based on the desired thickness of the electrolytic plating layer, etc.

[0060] Furthermore, the copper clad laminate 10 in this embodiment is formed by laminating the electroless copper plating layer 5 directly on 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.

[0061] <Method for manufacturing copper clad laminate> Next, a method for manufacturing the copper clad laminate 10 of this embodiment will be described with reference to Figure 8. That is, in step 1, a vacuum plasma treatment is performed on the above-mentioned low dielectric resin film 1 as a first surface modification process. As an example, using the above-mentioned vacuum plasma treatment apparatus 100, a plasma treatment gas appropriate for the material of the low dielectric resin film is supplied to the film surface. As a result, 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.

[0062] In the subsequent step 2, a second surface modification step is performed by first 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 to the surface. By interposing such a Pd-supported layer 3 between the film and the electroless copper plating layer, it becomes possible to more reliably maintain the catalyst nuclei 4, which serve as the nuclei for plating deposition, on the film.

[0063] In the subsequent step 3, a catalyst adsorption step is performed in which catalytic nuclei 4 are adsorbed onto the low dielectric resin film 1 on which the Pd-supported 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.

[0064] By undergoing 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 laminated directly 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-fluorine-based resin, the peak area (P ａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) area ratio (P ａｒｅａ２ / P ａｒｅａ１ When the low dielectric resin film 1 is made of a fluorine-based resin, the copper clad laminate 10 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.

[0065] Furthermore, by undergoing the above process, a 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, can be obtained, 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 peak area (Pａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) area ratio (P ａｒｅａ２ / P ａｒｅａ１ ) is 1.25 or more and 2.00 or less.

[0066] In this embodiment, the description has been given up to the formation of the electroless copper plating layer 5 in step 4. 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) step of heating the copper clad laminate 10 on which the electroless copper plating layer 5 has been formed. Furthermore, after the heating (annealing) step of heating the copper clad laminate 10, the process may further include a resist patterning step of forming a resist on the electroless copper plating layer 5, an electrolytic copper plating step of forming an electrolytic copper plating layer 6 between the patterned resist, a resist removal step of removing the patterned resist, and the like.

[0067] As described above, the method for manufacturing a copper clad laminate in this embodiment is a method for manufacturing 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 loss tangent of 0.008 or less, and is characterized by including at least a first surface modification step of 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. Each step will be described in detail below.

[0068] [Plasma Treatment of Low Dielectric Resin Film: First Surface Modification Step] First, in the first surface modification step, 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 shown in Figure 4. The vacuum plasma treatment can be performed, for example, by preparing the low dielectric resin film 1, using the bonding 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 electrode and another electrode supported insulated to generate a glow discharge. During the vacuum plasma treatment, the grounded electrode takes the form of a cooling roll to prevent the temperature of the transported material from rising.

[0069] In the vacuum plasma treatment in the first surface modification step described above, the bonding surface of the low dielectric resin film 1 is subjected to vacuum plasma treatment using a plasma treatment gas (active gas or inert gas) under vacuum, which cleaves molecules present on the low dielectric resin film 1 to generate functional groups, thereby enabling 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.

[0070] Here, the output condition in the vacuum plasma treatment of this embodiment is 0.05 W / cm ２ ~2.00 W / cm ２ It is also preferable to change the type of gas supplied from the processing gas supply source 140 and the output conditions depending on the material of the low dielectric resin film 1 .

[0071] More specifically, for example, when the low dielectric resin film 1 is a non-fluorine-based resin (such as COC, COP, SPS, LCP, PPS, or PEEK), oxygen is preferably used as the plasma treatment gas from the viewpoint of cleaving bond energy (such as C-H bonds or C-C bonds) and generating functional groups (hydroxyl groups and / or carboxyl groups). In particular, when the low dielectric resin film 1 is a cycloolefin-based resin (such as the above-mentioned COC or COP), it is more preferable to perform oxygen plasma treatment with a relatively low output as the plasma treatment gas output condition, since the above-mentioned molecular cleavage does not require particularly strong energy. Furthermore, when the low dielectric resin film 1 is a resin containing an aromatic ring (such as the above-mentioned SPS, LCP, PPS, or PEEK), it is more preferable to perform oxygen plasma treatment with a relatively high output as the plasma treatment gas output condition, since the molecular cleavage of the aromatic ring requires relatively strong energy.

[0072] Furthermore, for example, when the low dielectric resin film 1 is a fluorine-based resin (such as the above-mentioned PTFE or PFA), it is necessary to cut the C—F bond, which has high bond energy, and therefore it is preferable to use argon (Ar) as the plasma treatment gas.

[0073] It is preferable that the above-described vacuum plasma processing apparatus 100 further be equipped with a magnetron mechanism capable of generating a magnetic field in any direction. In the method for producing a copper clad laminate according to this embodiment, by installing the magnetron mechanism, it is possible to locally confine the plasma on the surface of the low dielectric resin film 1, and the output of the plasma processing gas can be increased to 0.05 W / cm. ２ ~2.00 W / cm ２ At a low output, 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).

[0074] When the above-mentioned magnetron mechanism is installed, the output condition of the plasma processing gas is preferably 0.05 W / cm ２ ~1.50 W / cm ２ , and more preferably 0.05 W / cm ２ ~1.20 W / cm ２ , particularly preferably 0.10 W / cm ２ ~1.20 W / cm ２ It is preferable that the treatment time of the plasma treatment gas is 50 to 1500 seconds, more preferably 50 to 1350 seconds, and even more preferably 80 to 1350 seconds. Controlling the treatment time within the above range is preferable because it is possible to improve 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. On the other hand, if the output conditions and treatment time of the plasma treatment gas are below the lower limit of the above range, sufficient adhesion between the low dielectric resin film 1 and the electroless copper plating layer 5 cannot be obtained, which is not preferable. If the output conditions and treatment time exceed the upper limit of the above range, it is also not preferable because the smoothness or flatness of the surface of the low dielectric resin film 1 may be impaired, which may increase transmission loss.

[0075] [Adding Charge to Low Dielectric Resin Film After Plasma Treatment: Second Surface Modification Step] After the vacuum plasma treatment is performed on the low dielectric resin film 1 by the method described above, as shown in Fig. 3, a second surface modification step can be performed in which a Pd-supported layer 3 (positive and negative charges) is added to the side of the low dielectric resin film 1 that has been subjected to the first surface modification treatment. By adding 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, as described below.

[0076] That is, it is preferable that catalytic nuclei that serve as nuclei for plating deposition are present on the film in order to form the electroless copper plating layer 5 on the low dielectric resin film 1. From this perspective, in order for the 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 step.

[0077] Therefore, in the second surface modification step of this embodiment, it is preferable to apply a negative charge to the surface to which a positive charge has been applied after applying a positive charge to the surface of the low dielectric resin film 1. By going through these steps, it is possible to reliably attach a negative charge to the surface of the low dielectric resin film 1.

[0078] Specific methods for imparting 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.

[0079] Specific methods for providing a negative charge on the surface of the low dielectric resin film 1 include, for example, immersion in a known anionic surfactant or spraying the anionic surfactant into contact with the low dielectric resin film 1. By using the above methods, a Pd-supported layer 3 is formed on the functional groups 2 of the low dielectric resin film 1 that has been subjected to the vacuum plasma treatment, as shown in FIG.

[0080] [Providing 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 whose surface has been charged by the second surface modification process described above, as exemplified in FIG.

[0081] 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 Cu, Ni, Ag, and the like, in addition to the above-mentioned metallic palladium Pd. Furthermore, examples of the above-mentioned known catalytic liquid include tin-palladium-based or palladium colloid-based catalytic liquids.

[0082] In the above-mentioned catalyst adsorption treatment, the amount of catalyst applied to the low dielectric resin film 1 is 30 μg / dm in terms of metallic palladium. ２ The lower limit of the catalyst content is preferably 5 μg / dm or less, taking into consideration the etching process during circuit formation. However, it is necessary to add the catalyst to such an extent that the electroless copper plating layer is well formed. ２ In the above-described catalyst adsorption step, the low dielectric resin film may be immersed for several minutes in an aqueous solution (at 25° C., for example) containing 1 g / L of dimethylamine borane (DMAB) and 6 g / L of boric acid as a catalyst activator (reducing agent), thereby reducing the catalyst cores 4.

[0083] [Formation of Electroless Copper Plated 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 step of forming an electroless copper plated layer on the surface of the low dielectric resin film 1 to which the above-mentioned catalytic nuclei 4 are adsorbed, using a known electroless copper plating bath such as an EDTA bath, a Rochelle bath, or a triethanolamine bath.

[0084] 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 is 50 nm to 1000 nm. The plating layer formed in this electroless copper plating process is not limited to plating of simple Cu, but may also be plating of a copper alloy, such as a Cu—Ni alloy, a Cu—Zn alloy, or a Cu—Sn alloy. By performing the above steps, the copper clad laminate 10 of this embodiment is manufactured.

[0085] Next, the present invention will be described in more detail with reference to examples. Example 1 First, COC (Coxec TCS-1, Kurabo Industries, Ltd., thickness: 25 μm) was prepared as a 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.

[0086] Next, as a first surface modification step, oxygen (O ２ The plasma treatment was carried out under the conditions of a vacuum plasma treatment apparatus 100 equipped with a magnetron mechanism and an output of 0.30 W / cm ２ The treatment time was 90 seconds.

[0087] Next, as a second surface modification step, 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 anionic surfactant for 1 minute. In this way, positive charges were adsorbed, and then negative charges were adsorbed.

[0088] Next, in the catalyst adsorption step, palladium chloride (PdCl ２ The plate was immersed in an aqueous solution (2 g / L, pH 12, 40°C) of dimethylamine borane (DMAB) at 1 g / L and boric acid at 6 g / L as a catalyst activator (reducing agent) at 25°C for 5 minutes, and then immersed and rinsed with water.

[0089] Thereafter, in the electroless copper plating step, an electroless Cu—Ni plating layer was formed to a thickness of 200 nm in an electroless plating bath under the following electroless plating conditions:

[0090] [Electroless Plating Conditions] Bath composition: copper sulfate 7.5 g / L, sulfuric acid 0.6 g / L, nickel sulfate 0.006 g / L, Rochelle salt 20 g / L, IPA 0.5 g / L, sodium hydroxide 6.8 g / L, formaldehyde 2.2 g / L, pH: 12.5, bath temperature: 45° C.

[0091] In this example, a copper clad laminate 10 was produced by the above-described method, in which an electroless copper plating layer 5 was formed on a low dielectric resin film 1. Note that the heating (annealing) treatment for the obtained copper clad laminate 10 was omitted.

[0092] <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 of the obtained copper clad laminate 10 with a known dissolving agent (for example, a 30% nitric acid solution). The surface properties of this film after plasma treatment were analyzed using the above-mentioned XPS (X-ray polymer spectroscopy).

[0093] 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 ), and the peak area (P ａｒｅａ１ ) and their area ratio (P ａｒｅａ２ / P ａｒｅａ１ The result of the calculation was "1.39".

[0094] <Tape Peel Strength> A test tape (manufactured by Nichiban Co., Ltd., width: 25 mm) was applied to the surface of the electroless copper plating layer 5 of a copper clad laminate 10 having an electroless copper plating layer 5 formed thereon, and the tape was then peeled off in accordance with the "Test Method for Plating Adhesion" described in JIS H 8504 (1999), to conduct the tape peel test described above. The test tape used was an adhesive tape specified in JIS Z 1522, with a nominal width of 12 to 19 mm. The adhesive strength of this test tape was specified as approximately 8 N (i.e., 3.48 N / cm) per 25 mm width. After peeling, if plating adhesion was visually confirmed on the adhesive surface of the peeled test tape, the adhesion was evaluated as poor and the result was ×; if no plating adhesion was confirmed, the result was evaluated as ⊚ (estimated to be 3.5 N / cm or more); and if only partial plating adhesion (a level acceptable for practical use) was confirmed, the result was evaluated as ◯.

[0095] <Surface Roughness Ra After Peeling Off Electroless Copper Plated Layer 5> The electroless copper plated layer 5 was peeled off from the obtained copper clad laminate 10 (electroless copper plated 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 DimensionIcon) at a viewing angle of 10 μm × 10 μm.

[0096] <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 x 20 mm, and the SiO ２ The element concentration ratio in the depth direction was calculated in 10 nm increments in terms of weight percent, and the Cu concentration [Cu / (Cu+Ni)] among the metal elements (Cu, Ni) when the Cu element concentration was at its maximum was calculated in weight percent. The results are summarized in Tables 1, 2, and 4, respectively.

[0097] 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: the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, and the output was 0.09 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1 and 2, respectively.

[0098] 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, and the output was 0.60 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1, 2 and 4, respectively.

[0099] 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, and the output was 0.09 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1 and 2, respectively.

[0100] 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, and the output was 0.60 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1, 2 and 4, respectively.

[0101] 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, and the output was 0.30 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1 and 2, respectively.

[0102] 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, and the output was 0.60 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1, 2 and 4, respectively.

[0103] 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, and the output was 0.09 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1 and 2, respectively.

[0104] Example 9 The same procedure as in 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) and the plasma treatment conditions were as shown in Table 1. Specifically, in this example, the vacuum plasma treatment apparatus 100 was not equipped with the magnetron mechanism described above, and the output was set to 0.31 W / cm ２ The processing time was 1260 seconds. The results are summarized in Tables 1 and 2, respectively.

[0105] 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, as in Example 9, the vacuum plasma treatment apparatus 100 was not equipped with the magnetron mechanism described above, and the output was set to 0.09 W / cm ２ The treatment time was 420 seconds. The results are summarized in Tables 1, 2 and 4, respectively.

[0106] 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: a magnetron mechanism was installed in the vacuum plasma treatment device 100, and an output of 0.60 W / cm ２ The treatment time was 90 seconds.

[0107] In this example, a film (corresponding to "FM3" in FIG. 6) was produced by dissolving the electroless copper plating layer 5 of the obtained copper clad laminate 10 with a known solvent. The surface properties of this film after plasma treatment were analyzed using the above-mentioned XPS (X-ray polymer spectroscopy).

[0108] 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 ), and the peak maximum intensity between 290.0 eV and 295.0 eV (I ＭＡＸ１ ) was measured, and the peak intensity ratio (I ＭＡＸ２ / I ＭＡＸ１ The calculated value was 4.90. The results are summarized in Tables 1, 3 and 4, respectively.

[0109] 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 as follows: the vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, and the output was 0.15 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1 and 3, respectively.

[0110] 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 included a vacuum plasma treatment apparatus 100 equipped with a magnetron mechanism and an output of 0.60 W / cm. ２ The treatment time was 90 seconds. The results are summarized in Tables 1, 3 and 4, respectively.

[0111] 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 vacuum plasma treatment apparatus 100 was equipped with a magnetron mechanism, and the output was 0.15 W / cm ２ The treatment time was 90 seconds. The results are summarized in Tables 1 and 3, respectively.

[0112] Comparative Example 1 The same procedure as in Example 1 was carried out, except that the first surface modification treatment was a known wet treatment as disclosed in Patent Documents 3 to 6, instead of 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 onto both surfaces, followed by immersion and rinsing with water. The temperature of the mixed solution used was 45°C. The results are summarized in Tables 1 and 2.

[0113] Comparative Example 2 The same procedure as in Comparative 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). The results are summarized in Tables 1 and 2.

[0114] Comparative Example 3 The same procedure as in Comparative 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). The results are summarized in Tables 1 and 2.

[0115] Comparative Example 4 The same procedure as in Comparative Example 1 was carried out, except that the low dielectric resin film 1 was PEEK (EXPEEK, manufactured by Kurabo Industries, Ltd., thickness: 50 μm). The results are summarized in Tables 1 and 2.

[0116] 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.

[0117] Comparative Example 6 was carried out in the same manner as in Example 11, except that the first surface modification treatment was carried out by the known wet treatment described in Patent Documents 3 to 6 instead of the vacuum plasma treatment. The wet treatment was the same as in Comparative Example 1. The results obtained by summarizing the above are shown in Tables 1 and 3.

[0118] 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 Industry Co., Ltd., thickness: 50 μm). The results are summarized in Tables 1 and 3.

[0119] 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 formation of the electroless copper plating layer 5. The results are summarized in Tables 1 and 2.

[0120] Comparative Example 9 The same procedure as in Comparative Example 8 was carried out, except that the low dielectric resin film 1 was SPS (Oidys CN, manufactured by Kurabo Industries, Ltd., thickness: 50 μm). The results are summarized in Tables 1 and 2.

[0121] Comparative Example 10 The same procedure as in Comparative Example 8 was carried out, except that the low dielectric resin film 1 was PPS (TORELINA 3030, manufactured by Toray Industries, Inc., thickness: 50 μm). The results are summarized in Tables 1 and 2.

[0122] Comparative Example 11 The same procedure as in Comparative Example 8 was carried out, except that the low dielectric resin film 1 was PEEK (EXPEEK, manufactured by Kurabo Industries, Ltd., thickness: 50 μm). The results are summarized in Tables 1 and 2.

[0123] 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 formation of the electroless copper plating layer 5. The results are summarized in Tables 1 and 3.

[0124] 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 Industry Co., Ltd., thickness: 50 μm). The results are summarized in Tables 1 and 3.

[0125]

[0126]

[0127]

[0128]

[0129] The copper clad laminate of the present invention can suppress transmission loss while ensuring high adhesion at the interface between the low dielectric film and the electroless copper plating layer, and 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.

[0130] REFERENCE SIGNS LIST 1 Low dielectric resin film 2 Functional group 3 Pd-supported layer 4 Catalytic core 5 Electroless copper plating layer 6 Electrolytic copper plating layer 10, 20 Copper clad laminate

Claims

1. A copper clad laminate comprising: a low dielectric resin film 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; and an electroless copper plating layer laminated directly onto at least one surface of the low dielectric resin film.

2. 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, ａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) area ratio (P ａｒｅａ２ / P ａｒｅａ１ ) is 1.25 or more and 2.00 or less.

3. The peak area (P) of the low dielectric resin film at 282.0 eV to 290.0 eV in the peak obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS) on the surface of the low dielectric resin film ａｒｅａ２ ) and the peak area (P ａｒｅａ１ ) and the area ratio (P ａｒｅａ２ / P ａｒｅａ１ 2. The copper clad laminate of claim 1, wherein the coefficient of friction coefficient is 0.9 or more.

4. The copper clad laminate according to 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 peaks obtained by waveform separation of C (carbon) in X-ray photoelectron spectroscopy (XPS).

5. The maximum peak intensity (I ＭＡＸ２ ) and the peak maximum intensity between 290.0 eV and 295.0 eV (I ＭＡＸ１ ) and the intensity ratio (I ＭＡＸ２ / I ＭＡＸ１ 5. The copper clad laminate according to claim 4, wherein the coefficient of friction coefficient is 1.00 or more.

6. 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.

7. 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.

8. The copper clad laminate according to any one of claims 1 to 5, wherein the electroless copper plating layer has a thickness of 50 nm to 1000 nm.

9. 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.

10. 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, the method comprising: 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 side of the low dielectric resin film that has been surface modified by the vacuum plasma treatment.

11. A method for producing a copper clad laminate as described in claim 10, further comprising a second surface modification process for applying an electric charge to the side of the low dielectric resin film that has been subjected to the first surface modification process, and a catalyst adsorption process for adsorbing catalytic nuclei to the side to which the electric charge has been applied, wherein the electroless copper plating layer is formed on the side to which the catalytic nuclei have been adsorbed.

12. The method for producing a copper clad laminate according to claim 11, wherein the first surface modification step includes a step of imparting carboxyl groups and / or hydroxyl groups to the surface of the low dielectric resin film.

13. 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.

14. 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.

15. The method for producing a copper clad laminate according to claim 12, wherein the low dielectric resin film is made of a resin containing fluorine.

16. 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.

17. The output condition in the vacuum plasma treatment is 0.05 W / cm ２ ~2.00 W / cm ２ The method for producing a copper clad laminate according to any one of claims 10 to 16,

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