Method for producing resin-plated material

Abstract

To provide a method for producing a resin-plated material by which the adhesive strength between a base material and a plating layer can be made higher than that in the conventional method without substantially forming ruggedness on the surface of the base material.SOLUTION: The method includes a step (a) of preparing a base material made of an insulating resin material, a step (b) of irradiating a surface of the base material with ultraviolet rays in an atmosphere containing oxygen to modify a region from the surface of the base material to a predetermined depth into a microporous layer including pores having a size of nm order in the base material, and a step (c) of performing a plasma treatment on the base material to remove a part of the microporous layer. The method includes a step (d) of imparting a hydrophilic functional group to the surface of a base material, a step (e) of supporting a catalyst on the base material after the step (d), and a step (f) of forming an electroless plating layer on the surface of the base material via the catalyst after the step (e).SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin-plated product. [Background technology]

[0002] Conventionally, wiring boards have been known in which a wiring pattern is provided on the surface of an insulating resin material. Conventionally, such wiring boards have been obtained by providing an electroless plating layer called a seed layer on a resin base material, and then providing an electrolytic plating layer on top of that.

[0003] To obtain stable electrical properties, the resin and the electroless plating layer (seed layer) must adhere firmly to each other. A conventional method for improving adhesion is to roughen the surface of the resin to create irregularities, and then form a seed layer on the surface of the resin with the irregularities formed. The anchor effect resulting from the existence of the irregularities firmly fixes the resin and seed layer together.

[0004] Incidentally, the 5G communications system, which has been under development in recent years, will utilize extremely high-frequency electrical signals. Such high-frequency currents flow only on the surface of the conductor, with difficulty flowing through the center due to a phenomenon known as the skin effect. If the surface of the conductor is uneven, the signal transmission path will become longer, resulting in increased transmission loss. Therefore, wiring boards, especially those intended to handle high-frequency signals, are required to minimize the unevenness of the conductor surface.

[0005] In light of the above circumstances, the following technologies of Patent Documents 1 and 2 have been proposed in the past. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-080480 [Patent Document 2] Japanese Patent Publication No. 2023-080489 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide a method for producing a resin-plated product that makes it possible to improve the adhesive strength between a substrate and a plating layer compared to conventional methods without creating substantial irregularities on the surface of the substrate. [Means for solving the problem]

[0008] The method for producing a resin-plated product according to the present invention comprises the steps of: A step (a) of preparing a substrate made of an insulating resin material; a step (b) of irradiating the surface of the substrate with ultraviolet light in an oxygen-containing atmosphere to modify a region from the surface of the substrate to a predetermined depth into a microporous layer containing voids of nanometer order size in the substrate; (c) subjecting the substrate to a plasma treatment to remove a portion of the microporous layer; a step (d) performed after or together with the step (c) of providing hydrophilic functional groups on the surface of the substrate; After the step (d), a step (e) of supporting a catalyst on the substrate; The method is characterized by comprising, after the step (e), a step (f) of forming an electroless plating layer on the surface of the base material via the catalyst.

[0009] According to the above method, a portion of the electroless plated layer penetrates into the microporous layer formed on the surface region of the substrate, thereby creating a nano-level anchor effect between the substrate and the electroless plated layer, firmly fixing them together.

[0010] When using a resin-plated material as a package substrate and forming fine wiring on the top surface of this package substrate, the semi-amidative method is generally used. In this method, the resist formed in the wiring area is removed, and then a wiring pattern is formed in the wiring area. Then, the resist formed in areas other than the wiring area is removed, and the electroless plating layer formed in areas other than the wiring area is etched. At this time, catalyst residue is also removed to ensure insulation properties.

[0011] In the above configuration, since the electroless plating layer is formed on the surface of the substrate, the catalyst residue is largely contained in the electroless plating layer rather than in the resin substrate, so that catalyst removal and etching can be performed only on the electroless plating layer, which can suppress the progression of etching on the resin substrate and prevent a decrease in adhesion between the substrate and the electroless plating layer.

[0012] In this specification, the term "microporous layer" refers to a layer containing voids generated by partial cleavage of the polymer chains of the resin material constituting the substrate. These voids are on the order of nanometers (1 nm to several nanometers) in size. The presence and thickness of the microporous layer can be confirmed by observing the cross section of the resin-plated material with a TEM (transmission electron microscope).

[0013] As described above, the microporous layer is formed for the purpose of firmly fixing the substrate and the electroless plating layer by allowing a portion of the electroless plating layer to penetrate in. Step (b) is performed for the purpose of forming such a microporous layer in the surface region of the substrate.

[0014] On the other hand, since the microporous layer is a layer containing voids generated by cleavage of some of the polymer chains of the resin material constituting the substrate, its strength is relatively weaker than that of the region of the substrate where the microporous layer is not formed. Therefore, if the thickness of the microporous layer is too thick, the proportion of the region of the substrate that has been depolymerized increases, which may reduce the strength of the substrate itself.

[0015] In contrast, according to the above method, after step (b), a plasma treatment is performed on the substrate in step (c), which removes a portion of the microporous layer, thereby reducing the thickness of the microporous layer and suppressing the phenomenon of a decrease in the strength of the substrate due to the presence of the microporous layer.

[0016] Furthermore, by carrying out step (d), hydrophilic functional groups are additionally imparted to the surface of the substrate, thereby further improving the adhesion between the electroless plating layer formed on the surface of the substrate and the substrate.

[0017] However, because the plasma treatment merely involves spraying a plasma-containing gas onto the surface of the substrate, the treatment alone does not have the effect of forming a microporous layer inside the substrate. The method of the present invention achieves the extremely novel effect of forming a microporous layer in a region extending from the surface of the substrate to a predetermined depth by carrying out step (b), reducing the thickness of the microporous layer by carrying out step (c), and further imparting hydrophilic functional groups to the surface of the substrate by carrying out step (d), thereby strengthening the adhesion between the substrate and the electroless plating layer while maintaining the strength of the substrate.

[0018] The main purpose of step (c) is to irradiate the surface of the substrate with plasma to etch a part of the microporous layer near the surface. From this viewpoint, step (c) is performed, for example, at a plasma density of 1×10 10 / cm 3 ~1×10 12 / cm 3 It is preferable to spray a gas containing a relatively high density of plasma onto the surface. An HCD plasma generator using hollow cathode discharge is suitable for generating such high density plasma. Other examples of such devices include CCP, ECR, and ICP. The plasma treatment may be performed in a medium vacuum environment or a substantial vacuum environment with a pressure of 100 Pa or less, or in an atmospheric pressure environment.

[0019] The purpose of step (d) is to provide hydrophilic functional groups to the surface of the substrate. One example of step (d) is a method of performing an oxidative plasma treatment on the surface of the substrate. More specifically, a method can be employed in which a plasma-containing gas obtained by generating a discharge in a gas containing one or more selected from the group consisting of oxygen, nitrogen, hydrogen, argon, etc. is converted into plasma, and the plasma-containing gas is irradiated onto the surface of the substrate.

[0020] As an alternative method for step (d), a method of contacting a solution containing a self-assembled monolayer-forming material with the substrate (liquid phase method) or a method of subjecting the substrate surface to corona discharge may be used.

[0021] The resin material constituting the substrate is not particularly limited as long as it exhibits insulating properties. Specific examples of the resin material include one or more selected from the group including polyimide resin, liquid crystal polymer, polystyrene, polyphenylene sulfide, polyether ether ketone, polyethylene naphthalate, cycloolefin polymer, cyclic olefin copolymer, polytetrafluoroethylene, polyurethane, phenolic resin, and epoxy resin.

[0022] The ultraviolet light irradiated in step (b) may have a light output at a wavelength of 200 nm or less. More preferably, the ultraviolet light irradiated in step (b) may have a main peak wavelength or a sub-peak wavelength of 200 nm or less.

[0023] Here, the "main peak wavelength" refers to the wavelength with the highest light intensity in the spectrum of light emitted from a light source. Furthermore, the "sub-peak wavelength" refers to a wavelength with a lower light intensity than the main peak wavelength, but with a higher light intensity than the wavelengths before and after the sub-peak wavelength. For example, a wavelength around 185 nm in the spectrum of ultraviolet light emitted from a low-pressure mercury lamp corresponds to the sub-peak wavelength. On the other hand, a wavelength around 172 nm in the spectrum of ultraviolet light emitted from a Xe2 excimer lamp corresponds to the main peak wavelength.

[0024] To reiterate, the main purpose of step (c) is to irradiate the surface of the substrate with plasma to etch a portion of the microporous layer near the surface. From the viewpoint of achieving this purpose, there are no particular limitations on the type of gas used to generate the plasma. In other words, step (c) may be a reducing plasma treatment or an oxidizing plasma treatment. For example, if in step (c) the surface of the substrate is irradiated with plasma obtained by generating a discharge in a gas containing hydrogen, a reducing plasma treatment is performed on the surface of the substrate. Also, if in step (c) the surface of the substrate is irradiated with plasma obtained by generating a discharge in a gas containing oxygen, an oxidizing plasma treatment is performed on the surface of the substrate.

[0025] Here, by performing an oxidative plasma treatment in step (c), hydrophilic functional groups can be imparted to the surface of the substrate. In other words, in this case, step (d) is performed concomitantly with step (c), which makes it possible to simplify the process.

[0026] The region where a portion of the electroless plated layer penetrates into the microporous layer is preferably a region between the surface of the base material and a depth of 20 nm or more from the surface of the base material.

[0027] However, if the depth of the region where the electroless plating layer penetrates into the microporous layer is too deep, when a wiring is formed using this resin-plated material, a high proportion of the current flows through the portion of the electroless plating layer that penetrates into the microporous layer when the wiring is energized. The region of the electroless plating layer formed within the microporous layer contains a metal catalyst such as palladium, which has a lower electrical conductivity than copper, so the flow of high-frequency current may lead to increased conductor loss.

[0028] From this perspective, the depth range of the region where part of the electroless plated layer penetrates into the microporous layer may be 100 nm or less.

[0029] In view of the above, the thickness of the microporous layer obtained after step (b) is 30 nm to 190 nm; The step (c) is a step of reducing the thickness of the microporous layer obtained in the step (b), and may be a step of reducing the thickness of the microporous layer to 20 nm to 100 nm. [Effects of the Invention]

[0030] According to the present invention, a resin-plated product can be obtained in which the adhesive strength between the substrate and the plating layer is improved without providing substantial irregularities on the surface of the substrate. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a cross-sectional view schematically showing the structure of one embodiment of a resin-plated product of the present invention. [Figure 2] 1 is a diagram schematically illustrating the structure of a microporous layer. [Figure 3] FIG. 1 is a cross-sectional view schematically showing the structure of a resin-plated product including a patterned electroplated layer. [Figure 4] 1 is a diagram schematically showing the results of an elemental analysis performed by EDS on a cross-sectional image of the vicinity of the surface of a substrate included in a resin-plated product, obtained using STEM-EDX. [Figure 5] This is an example of the results of a cross-sectional image of the surface vicinity of a base material included in a resin-plated product obtained using STEM-EDX, and element distribution was determined using EDS. [Figure 6] This is a diagram showing the results of fitting the results of Figure 5 with a curve that has been subjected to 10-point smoothing processing. [Figure 7] 1 is a flowchart showing the steps of one embodiment of a method for producing a resin-plated product. [Figure 8] 1 is a diagram schematically illustrating one procedure in a method for producing a resin-plated product. [Figure 9] 1 is a diagram schematically illustrating one procedure in a method for producing a resin-plated product. [Figure 10] 1 is a diagram schematically illustrating one procedure in a method for producing a resin-plated product. [Figure 11] 1 is a diagram schematically illustrating one procedure in a method for producing a resin-plated product. [Figure 12] 10 is a flowchart showing the steps of another embodiment of a method for producing a resin-plated product. [Figure 13A] 10 is a graph corresponding to the results of verification 1. [Figure 13B] 1 is a graph showing the relationship between the presence or absence of plasma treatment, the plasma treatment time, and the water contact angle. [Figure 14] The graph shows the results of ATR-FTIR analysis of an untreated substrate and a substrate that was irradiated with ultraviolet light without plasma treatment. [Figure 15] The graph shows the results of ATR-FTIR analysis of an untreated substrate and a substrate that was plasma-treated without UV irradiation. [Figure 16] The graph shows the results of ATR-FTIR analysis of a substrate that was irradiated with ultraviolet light without plasma treatment, and a substrate that was irradiated with ultraviolet light and then plasma treated. DETAILED DESCRIPTION OF THE INVENTION

[0032] An embodiment of the method for manufacturing a resin-plated product according to the present invention will be described below with reference to the accompanying drawings. The drawings are schematic illustrations, and the dimensional ratios shown in the drawings do not necessarily correspond to the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings may not correspond to each other.

[0033] For convenience of explanation, the structure of a resin-plated product obtained through the manufacturing method of this embodiment will be explained first, and then the manufacturing method of this embodiment will be explained.

[0034] [Structure of resin-plated materials] 1 is a cross-sectional view showing a schematic structure of a resin-plated product 1. As shown in FIG. 1, the resin-plated product 1 includes a base material 3 and an electroless plating layer 9 formed on the +Z side surface of the base material 3.

[0035] In the following drawings, the Z direction refers to the direction perpendicular to the main surface of the substrate 3. The main surface of the substrate 3 refers to the surface that is much larger in area than the other surfaces that make up the substrate 3. Of the main surfaces of the substrate 3, the surface on the +Z side, i.e., the surface on which the electroless plating layer 9 is formed, may be referred to as the "surface 3a" of the substrate 3 for convenience. The direction from the surface 3a of the substrate 3 toward the substrate 3 side (-Z direction) may be referred to as the "depth direction" for convenience.

[0036] In this embodiment, the substrate 3 is made of an insulating resin material. Specific examples of materials for the substrate 3 include polyimide resin, liquid crystal polymer, polystyrene, polyphenylene sulfide, polyether ether ketone, polyethylene naphthalate, cycloolefin polymer, cyclic olefin copolymer, polytetrafluoroethylene, polyurethane, phenolic resin, and epoxy resin, and a mixture of these materials may also be used. The substrate 3 may be a sheet-like film or a plate-like member.

[0037] The substrate 3 includes a microporous layer 5 formed from the surface 3a of the substrate 3 to a thickness D1. The microporous layer 5 is a layer formed by modifying the substrate 3, as described below. The thickness D1 is 20 nm or more, and more preferably 30 nm or more. The thickness D1 is preferably 100 nm or less. As will be described later in the description of the manufacturing method, the thickness D1 of the microporous layer 5 is adjusted by etching a portion of the microporous layer 5 after the microporous layer 5 is formed.

[0038] FIG. 2 is a diagram schematically illustrating the structure of the microporous layer 5. The substrate 3 is made of a polymeric resin material. As will be described later, the microporous layer 5 corresponds to a layer formed when the substrate 3 is irradiated with ultraviolet light, resulting in cleavage of some of the polymer chains of the resin material and oligomerization. When the polymeric material is oligomerized, spaces (voids 4) are formed between the oligomers. The microporous layer 5 corresponds to a layer containing voids 4 as a result of modifying a portion of the substrate 3 in this manner. The voids 4 are on the order of nanometers (1 nm to several nanometers) in size.

[0039] As shown in Fig. 1, a catalyst 7 is supported within a microporous layer 5 provided on a substrate 3 of a resin-plated product 1. The catalyst 7 may be any compound containing molecules or atoms that exhibit catalytic effects (hereinafter referred to as a "catalytic compound"), and typically a substance containing Pd is used, but Ni, Ag, etc. can also be used.

[0040] As shown in FIG. 1, the electroless plated layer 9 is formed on the +Z side surface of the substrate 3, and more specifically, is located above the microporous layer 5. As shown in FIG. 1, a portion of the electroless plated layer 9 penetrates into the microporous layer 5 in the depth direction. More specifically, the electroless plated layer 9 penetrates into the microporous layer 5 from the surface of the substrate 3 to a depth D2. The depth D2 is 20 nm or more, and more preferably 35 nm or more. Furthermore, the depth D2 is preferably 100 nm or less. Because this depth D2 is also the thickness of the electroless plated layer 9 that penetrates into the microporous layer 5, it may be referred to as "thickness D2" below.

[0041] The electroless plating layer 9 is typically a film made of a conductive material containing Cu, but may also be a film made of a conductive material containing other metal elements such as Ni.

[0042] As described above, the catalyst 7 is supported within the microporous layer 5. Therefore, at a position within the microporous layer 5, the electrons released when the reducing agent is decomposed on the catalyst 7 can be received by metal ions containing elements that constitute the electroless plated layer 9. As a result, the electroless plated layer 9 is also formed at a position within the microporous layer 5.

[0043] That is, according to the above configuration, the electroless plated layer 9 penetrates into the microporous layer 5 to a depth D2 of 20 nm or more. This creates a nano-level anchor effect between the substrate 3 and the electroless plated layer 9, firmly fixing them together. Details will be described later with reference to examples.

[0044] Fig. 3 is a cross-sectional view schematically showing a state in which a patterned electrolytic plated layer 11 has been formed on the resin-plated material 1 shown in Fig. 1. After the electrolytic plated layer 11 has been formed on the upper surface of the electroless plated layer 9 of the resin-plated material 1 shown in Fig. 1, a patterning step according to the wiring pattern is carried out. As a result, a predetermined region A1 is etched in the depth direction, and the base material 3 is exposed.

[0045] Here, near the +Z side surface (surface 3a) of the substrate 3, the electroless plated layer 9 penetrates into the substrate 3, more specifically, into the microporous layer 5. Therefore, during etching, the proportion of the electroless plated layer 9 that is etched increases, and the amount of etching of the substrate 3 made of a resin material can be reduced. As a result, it is possible to prevent a decrease in adhesion between the substrate 3 and the electroless plated layer 9 when forming a wiring pattern.

[0046] Returning to Figure 1, the explanation continues. The thickness D1 of the microporous layer 5 formed near the surface 3a of the substrate 3 and the depth D2 to which the electroless plated layer 9 penetrates into the microporous layer 5 can both be confirmed by analyzing images of the resin-plated material 1 taken with a STEM (Scanning Transmission Electron Microscope). More specifically, these can be confirmed by photographing the resin-plated material 1 using a STEM equipped with an EDX (Energy Dispersive X-ray Spectrometer) or EELS (Electron Energy Loss Spectrometer) and understanding the change in elemental composition in the depth direction.

[0047] 4 is a diagram showing the results of elemental analysis using STEM-EDX on the surface 3a and the vicinity of the substrate 3 of the resin-plated product 1. The vertical axis represents signal intensity, and the horizontal axis represents the distance traveled in the depth direction (-Z direction) from the side of the resin-plated product 1. In the following description, it is assumed that a material containing Cu is used for the electroless plating layer 9 and a material containing Pd is used for the catalyst 7.

[0048] As will be described later, the catalyst 7 is applied to the substrate 3 before the electroless plating layer 9 is formed by immersing the substrate 3 in a solution containing the catalyst 7 for the purpose of growing the electroless plating layer 9. For this reason, it is expected that the catalyst 7 will be supported at the highest rate on the surface 3a of the substrate 3. From this perspective, it can be determined from the STEM-EDX analysis results that the depth position corresponding to the peak value of the Pd signal intensity corresponds to the depth position in the surface 3a of the substrate 3. At this time, the electroless plating layer 9 is formed shallower than the surface 3a.

[0049] 4, the presence of a Pd signal is observed even deeper than the surface 3a of the substrate 3. This suggests that a microporous layer 5 containing voids 4 is formed near the surface 3a of the substrate 3, and Pd as a catalyst 7 is incorporated into the voids 4 within the microporous layer 5. The Pd signal intensity attenuates as the depth increases and eventually reaches the detection limit. The depth position at which the Pd signal reaches the detection limit can be inferred to be a position where there is no microporous layer 5 containing voids 4 for supporting Pd. From this perspective, the thickness D1 of the microporous layer 5 can be determined by the distance traveled in the depth direction from the depth position at which the Pd signal intensity peaks to the depth position at which the Pd signal intensity reaches the detection limit.

[0050] 4, the presence of Cu signals is observed even deeper than the surface 3a of the substrate 3. This suggests that an electroless plated layer 9 is formed in the microporous layer 5 via the catalyst 7 incorporated in the microporous layer 5. In other words, this indicates that the electroless plated layer 9 has penetrated into the substrate 3, more specifically, into the microporous layer 5 formed by modifying the substrate 3.

[0051] Within the microporous layer 5, the Cu signal intensity attenuates as the depth increases and eventually reaches the detection limit. The depth position at which the Cu signal reaches the detection limit can be inferred to be the position at which the formation of the electroless plated layer 9 has not yet been realized. From this perspective, the thickness D2 of the electroless plated layer 9 that penetrates into the substrate 3, in other words, the thickness D2 of the electroless plated layer 9 that penetrates into the microporous layer 5, can be determined by the distance traveled in the depth direction from the depth position at which the Pd signal intensity peaks to the depth position at which the Cu signal intensity reaches the detection limit.

[0052] However, the detection limits of the Pd and Cu signal intensities may vary depending on the measurement accuracy of the STEM-EDX device. From this perspective, the thickness D1 of the microporous layer 5 and the thickness D2 of the electroless plated layer 9 embedded in the substrate 3 were determined by using a curve obtained by smoothing the results of elemental analysis using STEM-EDX at 10 points using a simple moving average method. Specifically, in the curve obtained by smoothing 10 points at equal intervals of 1 mm, the thickness D1 of the microporous layer 5 was determined from the depth position where the Pd signal intensity peaked to the position where the signal intensity was 2% of the peak value. Furthermore, the thickness D2 of the electroless plated layer 9 was determined from the depth position where the Pd signal intensity peaked to the position where the signal intensity was 1% of the peak value of the Cu signal intensity. Because the Pd signal intensity is smaller than the Cu signal intensity, the noise ratio of the base portion to the peak intensity is large. Therefore, the thickness of the microporous layer 5 was determined to be the depth position where the signal intensity was up to 2% of the peak value of the Pd signal intensity.

[0053] Fig. 5 shows an example of the results of element distribution measurement by energy dispersive spectroscopy (EDS) using a STEM-EDX (JEM-ARM200F, manufactured by JEOL Ltd.) to obtain a cross-sectional image of the resin-plated product 1 at a position near the surface 3a of the substrate 3. It can be seen that the graph shown in Fig. 5 has a similar tendency to the graph shown schematically in Fig. 4.

[0054] 6 is a graph in which the thickness D1 of the microporous layer 5 and the thickness D2 of the electroless plated layer 9 that penetrates into the substrate 3 are specified using a method described below and added to the graph shown in FIG. 6. In the example of FIG. 6, the thickness D1 of the microporous layer 5 is 100 nm (a depth region from the Pd peak position of 110 nm to the Pd termination position of 210 nm), and the thickness D2 of the electroless plated layer 9 that penetrates into the substrate 3 is 50 nm (a depth region from the Pd peak position of 110 nm to the Pd termination position of 160 nm).

[0055] From the above perspective, in this specification, the thickness D1 of the microporous layer 5 and the thickness D2 of the electroless plated layer 9 that penetrates into the substrate 3 are each defined as values ​​measured for the resin-plated material 1 using the following method.

[0056] First, STEM-EDX is used to measure the element distribution near the interface of the resin-plated product 1. An example of an apparatus for measuring the element distribution is JEM-ARM200F (manufactured by JEOL Ltd.), but the apparatus is not limited to this example as long as it has a similar function.

[0057] More specifically, the following method can be used, for example. The resin-plated material 1 is cut into small pieces approximately 0.3 mm square, and then sliced ​​to a thickness of approximately 30 nm using an ultramicrotome (Leica EM UC7) to obtain a sample. This sample is then fixed to a sample holder in a STEM device. STEM-EDX measurement is then performed at an accelerating voltage of 200 kV, and element distribution intensity curves for Pd and Cu are obtained, with the horizontal axis representing depth and the vertical axis representing element distribution intensity. Figure 5 shows a graph obtained using this method.

[0058] Next, the element distribution intensity curves of Pd and Cu, as shown in Figure 5, are subjected to 10-point smoothing using the simple moving average method (see Figure 6). In the Pd curve obtained by this smoothing process, a position Pd1 indicating the peak value of Pd and a position Pd2 indicating an intensity value 2% of the peak value of Pd (where Pd2 > Pd1) are identified. The thickness D1 of the microporous layer 5 is then determined as the thickness (Pd2 - Pd1) between the Pd peak position PD1 and the Pd end position Pd2.

[0059] Next, in the Cu curve obtained by the smoothing process, the position Cu1 showing the Cu peak value and the Cu termination position Cu2 showing an intensity value 1% of the Cu peak value (where Cu2>Cu1) are identified. Then, the thickness D2 of the electroless plated layer 9 penetrating into the substrate 3 is determined as the thickness (Cu2-Pd1) between the Pd peak position Pd1 and the Cu termination position Cu2.

[0060] Any software can be used to perform the 10-point smoothing process, such as Igor Pro 9.02 (WaveMetrics). Figure 6 shows a curve obtained using the software, and even if different software is used to perform the 10-point smoothing, the variation in the thickness D1 and thickness D2 values ​​remains within a range of ±3%.

[0061] [Manufacturing method for resin-plated materials] Next, an example of a method for manufacturing the above-described resin-plated product 1 will be described with reference to Fig. 1. Fig. 7 is a flowchart showing an example of a method for manufacturing the resin-plated product according to this embodiment. In the following description, the step numbers in Fig. 7 will be referred to as appropriate.

[0062] (Step #1) As shown in Fig. 8, a base material 3 made of the above-mentioned resin material is prepared. This step #1 corresponds to the process (a).

[0063] In step #1, the substrate 3 may be heated at a predetermined temperature to remove the organic solvent residue adhering to the surface of the substrate 3. An example of the heating conditions is 100° C. for 30 minutes.

[0064] In addition to the above heating, the substrate 3 may be heated to a temperature higher than 100°C but lower than the glass transition temperature of the resin material constituting the substrate 3. The heating temperature is preferably lower than 160°C. A typical example of heating conditions is 140°C for 30 minutes. This heating step is carried out for the purpose of increasing the hardness of the resin constituting the substrate 3. However, if the heating temperature is too high, the substrate 3 becomes too hard, making it difficult to form the microporous layer 5 in the next step #3. Therefore, heating at a temperature lower than 160°C is preferable.

[0065] A specific method for performing the heat treatment on the base material 3 may be, for example, to place the base material 3 in a chamber including a heater and heat the base material 3 for a predetermined period of time. Another method may be to place the base material 3 on the upper surface of a stage equipped with a heating mechanism for a predetermined period of time. However, in this embodiment, it is optional whether or not to perform a heating step on the base material 3 before step #2, which will be described later.

[0066] (Step #2) Next, as shown in Fig. 9, ultraviolet light L1 is irradiated onto the substrate 3. The ultraviolet light L1 may be any light source as long as it has a light output at a wavelength of 200 nm or less. Preferably, the main peak wavelength or sub-peak wavelength of the ultraviolet light L1 is 200 nm or less.

[0067] The light source of the ultraviolet light L1 may be, for example, an Xe2 excimer lamp or a low-pressure mercury lamp. Alternatively, the light source of the ultraviolet light L1 may be a solid-state light source such as an LED or a laser diode.

[0068] Ultraviolet light with a wavelength of 200 nm or less, especially ultraviolet light with a wavelength of around 185 nm, is easily absorbed by oxygen (O2). Therefore, when ultraviolet light L1 is irradiated onto a resin substrate 3 in an atmospheric environment, part of the ultraviolet light L1 is absorbed by O2 in the atmosphere, and the ground state atomic oxygen O( 3 P) is generated. Note that the left side of equation (1) conveniently expresses the absorption of ultraviolet light of wavelength λ by O2, and μ represents the frequency of wavelength λ. O2+ hν(λ) → O( 3 P) + O( 3 P) ...(1)

[0069] Atomic oxygen O( 3 P) reacts with O2 in the atmosphere to produce ozone (O3) according to the following equation (2): O( 3 P) + O2 → O3...(2)

[0070] O3 has the property of absorbing ultraviolet light. When ultraviolet light is absorbed by O3, excited atomic oxygen O( 1 D) is produced. O3+ hν(λ) → O2+ O( 1 D) ...(3)

[0071] When ultraviolet light L1 is irradiated onto the surface 3a of the base material 3, part of the ultraviolet light L1 is absorbed by O2 in the atmosphere between the light source and the surface 3a, and the excited state atomic oxygen O( 1 D) is produced.

[0072] Atomic oxygen O( 1 D) has extremely high reactivity. m H n O k ) and cuts the molecular chain. In the following formula (4), m, m', n, n, k, and k' are all integers, with m>m', n>n', and k>k'. However, please note that formula (4) is a schematic representation of the reaction and is not an accurate chemical reaction formula. Cm H n O k + O( 1 D) → H2O, CO, CO2+ C m' H n' O k' ...(4)

[0073] The reaction breaks the polymer bonds of the resin material near the surface 3a of the substrate 3, modifying it into low-molecular-weight oligomers. As a result, the region near the surface 3a of the substrate 3 is modified into a microporous layer 5 containing voids 4, as described above with reference to FIG.

[0074] The thickness of the microporous layer 5 obtained in step #2 depends on the adhesion between the substrate 3 and the electroless plating layer 9 and From the viewpoint of ensuring the strength of the substrate itself, it is preferable that the thickness is set to 30 nm to 190 nm. The thickness of the microporous layer 5 can be appropriately set by adjusting the irradiation dose of the ultraviolet light L1.

[0075] This step #2 corresponds to process (b).

[0076] (Step #3) 10, the substrate 3 is subjected to a plasma treatment. More specifically, a plasma-containing gas PG1 is sprayed onto the surface of the substrate 3. As a result, a portion of the microporous layer 5 formed near the surface 3a of the substrate 3 is removed.

[0077] In this embodiment, it is assumed that the plasma-containing gas PG1 is an oxidizing gas, in which case hydrophilic functional groups 6 are additionally provided to the surface of the substrate 3 (the surface of the remaining microporous layer 5) while removing a portion of the microporous layer 5.

[0078] The reason why it is stated that the hydrophilic functional groups are "additionally added" here is that the hydrophilic functional groups are also added to the substrate 3 in the irradiation process of ultraviolet light L1 in step #2. For convenience of explanation, only the hydrophilic functional groups 6 added by spraying the oxidizing plasma-containing gas PG1 are shown in FIG.

[0079] More specifically, when the substrate 3 is irradiated with ultraviolet light L1, the ultraviolet light L1 travels into the substrate 3, imparting hydrophilic functional groups to the interior of the substrate 3. This is thought to be because, as described above, the microporous layer 5, i.e., the region where the reactive sites exist, is formed in step #2, and the hydrophilic functional groups imparted to the outermost surface of the substrate 3 are attracted in the depth direction where the reactive sites exist. In contrast, the plasma-containing gas PG1 does not penetrate into the substrate 3, so that only the outermost surface of the substrate 3 is treated in the plasma treatment of the substrate 3, and as a result, hydrophilic functional groups 6 are mainly imparted to the surface of the substrate 3.

[0080] The thickness of the microporous layer 5 remaining after step #3 is preferably set to 20 nm to 100 nm. The thickness of the remaining microporous layer 5 can be appropriately set by adjusting the plasma density in the plasma-containing gas PG1 and the plasma treatment time.

[0081] When the plasma-containing gas PG1 is an oxidizing gas, for example, a mixed gas of argon and oxygen can be used.

[0082] Step #3 is performed with the intention of etching the surface 3a of the substrate 3 to remove a portion of the microporous layer 5. From this perspective, it is preferable that the plasma-containing gas PG1 contains high-density plasma. Such high-density plasma can be suitably produced by a hollow cathode plasma (HCD plasma) generator. The HCD plasma generator is a device that generates plasma using, for example, a cylindrical cathode (hollow cathode), and can produce a high-density plasma jet.

[0083] The pressure inside the plasma generator may be atmospheric pressure or a pressure lower than atmospheric pressure, but is preferably a medium vacuum environment or a substantially vacuum environment of 0.01 Pa to 100 Pa. By performing hollow cathode discharge in an environment close to a vacuum, strong energy is imparted to the surface 3a of the substrate 3, achieving high etching efficiency. Note that by setting the pressure to 0.1 Pa to 100 Pa, the time required for pressure reduction can be made shorter than when a completely vacuum environment is achieved.

[0084] This step #3 corresponds to steps (c) and (d).

[0085] (Step #4) Next, as shown in Fig. 11, a catalyst 7 is applied to the substrate 3. As a specific example, the substrate 3 is immersed in a solvent containing a catalyst contributing compound.

[0086] In step #2, a microporous layer 5 containing voids 4 is formed on the substrate 3 from the surface 3a to a thickness D1. Therefore, by applying the catalyst 7 to such a substrate 3, the catalyst 7 is supported not only on the surface 3a of the substrate 3 but also in the microporous layer 5.

[0087] Furthermore, in step #3, hydrophilic functional groups 6 are additionally provided on the surface 3a of the substrate 3. Therefore, the catalyst 7 is attracted by the hydrophilic functional groups 6, and a large amount of the catalyst 7 is supported on the surface 3a of the substrate 3.

[0088] This step #4 corresponds to process (e).

[0089] (Step #5) 1, an electroless plated layer 9 is formed on the upper surface of the base material 3. As a specific example, the base material 3 is immersed in a plating solution containing the constituent materials of the electroless plated layer 9.

[0090] Through this process, an electroless plated layer 9 is formed on the upper surface of the substrate 3 via the catalyst 7. The plating solution also penetrates into the microporous layer 5, and because the catalyst 7 is also supported in this microporous layer 5, the electroless plated layer 9 also grows within the microporous layer 5. As a result, part of the electroless plated layer 9 penetrates into the interior of the substrate 3, more specifically, into the microporous layer 5.

[0091] This step #5 corresponds to process (f).

[0092] (post-process) Thereafter, post-processing is carried out, including a step of forming an electrolytic plated layer 11 on top of the electroless plated layer 9, whereby the resin-plated product 1 is obtained.

[0093] According to the above-described method, in step #3, the thickness D1 of the microporous layer 5, which has a relatively low strength, is reduced. This prevents a decrease in the strength of the resin-plated product 1 due to the presence of the microporous layer 5. Furthermore, the catalyst 7 is supported and the electroless plated layer 9 is formed in a state in which the hydrophilic functional groups 6 resulting from the plasma treatment are imparted to the surface 3a of the substrate 3 on which the microporous layer 5 is formed, thereby achieving the effect of firmly stabilizing the substrate 3 and the electroless plated layer 9.

[0094] [Another embodiment] 7, the plasma treatment in step #3 reduces the thickness D1 of the microporous layer 5 while additionally providing hydrophilic functional groups 6 to the surface of the substrate 3. However, the treatment for reducing the thickness D1 of the microporous layer 5 and the treatment for additionally providing hydrophilic functional groups 6 to the surface of the substrate 3 may be performed separately.

[0095] Fig. 12 is a flowchart showing the steps of another embodiment of the method for producing a resin-plated product. In the method shown in Fig. 12, after step #2, a plasma treatment using a reducing gas is performed to reduce the thickness D1 of the microporous layer 5 (step #3a), and then a plasma treatment using an oxidizing gas is performed to impart additional hydrophilic functional groups 6 to the surface of the substrate 3 (step #3b).

[0096] In this method, step #3b may have a lower plasma intensity than step #3a because it is not necessary to etch the surface of the substrate 3. In this method, step #3a corresponds to step (c), and step #3b corresponds to step (d). [Example]

[0097] Specific examples will be shown below to explain the present invention in more detail, but the present invention is not limited to these examples.

[0098] (Verification 1: Adhesion strength) The influence of the presence or absence of the plasma treatment in step #3 on the strength of the resulting resin-plated product was evaluated.

[0099] A COP resin (100 μm ZeonorFilm®, manufactured by Nippon SEON Co., Ltd.) defined by the following formula (5) was prepared as a sample of substrate 3. Using a light irradiation device (SVC 3 Series, manufactured by Ushio Inc., main peak wavelength 172 nm), ultraviolet light L1 was irradiated onto the surface of substrate 3 in a CDA (Clean Dry Air) atmosphere while the stage was being transported. The irradiation distance between the light source and substrate 3 was set to 5 mm. The irradiation dose of ultraviolet light L1 was measured using an illuminance meter (Ushio Inc., UIT-250 model) compatible with light with a wavelength of 172 nm.

[0100] [ka]

[0101] Next, using an HCD plasma generator (Shibaura Machine Co., Ltd., LPP-450), a plasma jet was generated under a pressure environment of 100 Pa or less and sprayed onto the surface 3a of the substrate 3. Specifically, the distance between the substrate 3 and the hollow cathode (electrode) was set to 150 mm, and a hollow cathode discharge was generated in a mixed gas of oxygen and argon (oxygen ratio of 90% by volume or more) to generate a plasma-containing gas PG1, which was then sprayed onto the surface 3a of the substrate 3. The spraying time of the plasma-containing gas PG1 (plasma treatment time) was set to 60 seconds or 120 seconds.

[0102] The substrate 3 was then immersed in a conditioner solution M1 to degrease the substrate and adjust the surface potential to a cation. After rinsing with water, the substrate 3 was immersed in a catalyst application solution M3 to apply a catalyst complex to the surface of the substrate 3. After rinsing with water, the substrate 3 was immersed in an activation treatment solution M4 to reduce the catalyst complex to a metal. After rinsing with water, the substrate 3 was immersed in an electroless metal plating solution M5 to reduce the metal ions via the catalyst, forming an electroless plating layer 9 on the substrate 3.

[0103] When immersing the substrate 3 in each chemical solution, the substrate 3 was dipped in a chemical solution pod storing the respective chemical solution for a predetermined time (several seconds to several minutes) and then removed. In addition, the water washing treatment was performed by dipping the substrate 3 in a cleaning pod storing cleaning water (pure water) for a predetermined time (several seconds to several minutes) and then removing it.

[0104] The chemicals used were as follows: Conditioner liquid M1: PB-102 and EC-B (both manufactured by JCU) Catalyst solution M3: A mixture of AISL-ACT (manufactured by JCU) and hydrochloric acid Activation treatment solution M4: A mixture of PCBA and PB-570B (both manufactured by JCU) Electroless metal plating solution M5: A mixture of PCBA, PB-570MU, PB-570B, and PB-570C (all manufactured by JCU).

[0105] For samples in which an electroless plating layer 9 was formed on a substrate 3, the adhesion between the substrate 3 and the electroless plating layer 9 was evaluated. Specifically, a stud pin was attached to the surface of the electroless plating layer 9 and pulled at a constant load rate, and the adhesion strength of the sample was measured using a method in accordance with the stud pull peel strength test method (MIL-SID-883).

[0106] (result) FIG. 13A is a graph corresponding to the results of Verification 1. In detail, FIG. 13A is a graph comparing the tensile strength of a sample that was not subjected to plasma treatment, a sample that was subjected to plasma treatment for 60 seconds, and a sample that was subjected to plasma treatment for 120 seconds. The ultraviolet light L1 irradiation treatment was performed at an illuminance of 600 mJ / cm. 2 was held.

[0107] The results in Figure 13A confirm that the adhesion strength of the samples (60s, 120s) in which the substrate 3 was irradiated with ultraviolet light L1 and then further subjected to plasma treatment was significantly increased compared to the sample (0s) in which the substrate 3 was irradiated with ultraviolet light L1 and then a catalyst was applied to form an electroless plating layer 9 without plasma treatment.

[0108] 13A, a sample that had been subjected to only plasma treatment without UV irradiation was prepared, and the tensile strength was measured using the same method as above. The adhesion strength was found to be lower than that of the sample that had been subjected to only UV irradiation. The reason for this is thought to be that although the plasma treatment provided hydrophilic functional groups 6 on the surface of the substrate 3, the absence of UV irradiation did not result in the formation of a microporous layer 5 inside the substrate 3 near its surface, and therefore the catalyst 7 was not incorporated into the substrate 3.

[0109] The reason why the adhesion strength between the substrate 3 and the electroless plating layer 9 was further increased by performing the ultraviolet irradiation treatment before the plasma treatment compared to the sample that had only been subjected to the plasma treatment is thought to be that the formation of a microporous layer 5 near the surface 3a of the substrate 3 allowed the catalyst 7 to be incorporated into the substrate 3, and that the additional addition of hydrophilic functional groups 6 to the surface of the substrate 3 allowed more of the catalyst 7 to be supported on the surface of the substrate 3.

[0110] 13B is a graph comparing the water contact angles of samples that were not plasma-treated after UV irradiation with those that were plasma-treated for a set time (30 seconds, 60 seconds, and 120 seconds). The water contact angles were measured using a water contact angle meter DMs-401FE manufactured by Kyowa Interface Science Co., Ltd.

[0111] 13B, it is confirmed that the water contact angle decreases rapidly when the plasma treatment is performed after the irradiation of ultraviolet light L1. This result indicates that the plasma treatment after the irradiation of ultraviolet light L1 on the substrate 3 promotes hydrophilization near the surface of the substrate 3, that is, the amount of hydrophilic functional groups near the surface of the substrate 3 increases.

[0112] Although not shown in Figure 13A, it was also confirmed that the adhesion strength of the sample subjected only to UV irradiation treatment was somewhat improved compared to the sample without any treatment, but the degree of improvement was limited. This is thought to be due to the fact that the formed microporous layer 5 was not thick enough, limiting the amount of catalyst 7 that could be incorporated into the substrate 3. By performing UV irradiation treatment to form a microporous layer 5 with a certain thickness, followed by plasma treatment, the residual thickness of the microporous layer 5, which causes a decrease in strength, is reduced while the amount of hydrophilic functional groups introduced is increased. As a result, the amount of catalyst 7 supported on the surface of the substrate 3 and inside the microporous layer 5 is increased, and the residual thickness of the microporous layer 5, which causes a decrease in strength, is reduced, dramatically improving the adhesion strength between the substrate 3 and the electroless plating layer 9.

[0113] (Verification 2: Effect of plasma treatment) As mentioned in Verification 1, one of the reasons why the adhesion strength was increased by performing plasma treatment after irradiating the substrate 3 with ultraviolet light L1 is thought to be that the microporous layer 5 formed on the surface 3a of the substrate 3 was etched, reducing the thickness of the microporous layer 5. The validity of this consideration was verified from another angle.

[0114] 14 shows the results of ATR-FTIR analysis of an untreated substrate 3 and a substrate 3 irradiated with ultraviolet light L1 without plasma treatment. The irradiation dose of ultraviolet light L1 was 600 mJ / cm. 2 The material of the substrate 3 was the same as that used in Verification 1. In FIG. 15, the horizontal axis indicates the wave number, and the vertical axis indicates the signal intensity. The signal intensity was measured at 2920 cm -1 The values ​​are expressed as relative values ​​normalized by the peak of CH stretching in the vicinity. This notation method is also used in Figs. 15 and 16 described later.

[0115] ATR-FTIR is a technique for obtaining an absorption spectrum near the surface of a sample by placing a crystal with a higher refractive index than the sample in close contact with the surface, irradiating the sample with infrared light from the crystal side, and measuring the total reflected light that penetrates and reflects near the surface. The measurement device used was a JASCO FT / IR-4600, and a Ge crystal was used as the high refractive index crystal. The angle of incidence of the infrared light was set to 45 degrees.

[0116] According to FIG. 14, when ultraviolet light L1 is irradiated, a wavelength of 3750 cm is emitted from the vicinity of the surface 3a of the base material 3. -1 ~3050cm -1 The signal corresponding to the OH stretching of 1720 cm -1 A signal corresponding to the nearby C=O stretching was confirmed with high intensity. From this result, it can be understood that the hydrophilic functional group was imparted to the resin substrate 3 by irradiating it with ultraviolet light L1.

[0117] Figure 15 shows the analysis results of ATR-FTIR measurements of an untreated substrate 3 and a substrate 3 that had been plasma-treated but not irradiated with ultraviolet light L1, performed in the same manner as in Figure 14. The plasma treatment times were set to 60 seconds and 120 seconds.

[0118] According to FIG. 15, by performing plasma treatment, the wave number of 1720 cm -1 It can be seen that the intensity of the signal corresponding to the C=O stretching near the base 3 increases. In other words, it can be seen that hydrophilic functional groups are also imparted by performing plasma treatment on the resin base 3. However, comparing Figures 14 and 15, it can be inferred that the amount of hydrophilic functional groups imparted is higher by UV light L1 irradiation treatment than by plasma treatment. From these results, it can be inferred that when UV light L1 is irradiated on the base 3, a microporous layer 5 is formed inside the base 3, and hydrophilic functional groups are imparted to the surface 3a of the base 3 and its vicinity. On the other hand, when only plasma treatment is performed on the base 3 without UV light L1 irradiation, hydrophilic functional groups are imparted only to the surface 3a of the base 3, resulting in a lower amount of hydrophilic functional groups imparted in the latter case than in the former case.

[0119] Figure 16 shows the results of ATR-FTIR analysis of a substrate 3 irradiated with ultraviolet light L1 without plasma treatment, and a substrate 3 irradiated with ultraviolet light L1 and then plasma treatment, using the same method as in Figure 14. The irradiation dose of ultraviolet light L1 was 600 mJ / cm. 2 The plasma treatment time was set to 60 seconds and 120 seconds.

[0120] According to FIG. 16, by performing plasma treatment after irradiation with ultraviolet light L1, the -1 ~3050cm -1 The intensity of the signal corresponding to the OH stretching of 1720 cm -1It can be seen that the intensity of the signal corresponding to the nearby C=O stretching decreased. This result suggests that a part of the microporous layer 5 formed by irradiation with ultraviolet light L1 was etched by plasma treatment, and the amount of hydrophilic functional groups present in the etched microporous layer 5 was reduced.

[0121] 14 to 16 show that a portion of the microporous layer 5 can be removed by irradiating the substrate 3 with ultraviolet light L1 and then performing a plasma treatment. This treatment reduces the thickness of the microporous layer 5, which has a relatively low strength, and thus prevents a decrease in the strength of the resin-plated product 1, which is formed by the substrate 3 and the electroless plated layer 9 in close contact with each other. Furthermore, by leaving the microporous layer 5 itself, the catalyst 7 can be supported within the microporous layer 5. This catalyst 7 then allows a portion of the electroless plated layer 9 to be incorporated into the substrate 3, thereby strengthening the adhesion strength between the substrate 3 and the electroless plated layer 9. This point was discussed above with reference to FIGS. 13A and 13B. [Explanation of symbols]

[0122] 1: Resin plating material 3: Base material 3a: Surface of the substrate 4 :Void 5: Microporous layer 6:Hydrophilic functional group 7: Catalyst 9: Electroless plating layer 11: Electroplated layer D1: Thickness of the microporous layer D2: Thickness of the electroless plating layer penetrating into the microporous layer L1: Ultraviolet light PG1: Plasma-containing gas

Claims

1. A step (a) of preparing a substrate made of an insulating resin material; a step (b) of irradiating the surface of the substrate with ultraviolet light in an oxygen-containing atmosphere to modify a region from the surface of the substrate to a predetermined depth into a microporous layer containing voids of nanometer order size in the substrate; (c) subjecting the substrate to a plasma treatment to remove a portion of the microporous layer; a step (d) performed after or together with the step (c) of providing hydrophilic functional groups on the surface of the substrate; After the step (d), a step (e) of supporting a catalyst on the substrate; A method for producing a resin-plated product, comprising, after the step (e), a step (f) of forming an electroless plating layer on the surface of the substrate via the catalyst.

2. The step (c) is a step of performing an oxidative plasma treatment on the substrate, 2. The method for producing a resin-plated product according to claim 1, wherein the step (d) is performed in association with the step (c).

3. the thickness of the microporous layer obtained after step (b) is 30 nm to 190 nm; 3. The method for producing a resin-plated product according to claim 1, wherein the step (c) is a step of reducing the thickness of the microporous layer obtained in the step (b), and the thickness of the microporous layer is set to 20 nm to 100 nm.

4. 3. The method for producing a resin-plated product according to claim 1, wherein the ultraviolet light irradiated in the step (b) has a light output of a wavelength of 200 nm or less.

5. 5. The method for producing a resin-plated product according to claim 4, wherein the ultraviolet light irradiated in the step (b) has a main peak wavelength or a sub-peak wavelength of 200 nm or less.

6. The step (b) is performed by adding Xe 2 6. The method for producing a resin-plated product according to claim 5, further comprising the step of irradiating the surface of the base material with the ultraviolet light from an excimer lamp.

7. 3. The method for producing a resin-plated product according to claim 1, wherein the step (c) is carried out using a hollow cathode plasma device.

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