Resin plating material and method for producing the same

Abstract

Provided is a resin plating material which, compared to prior art, has enhanced adhesive strength between a base material and a plating layer, without unevenness being substantially provided on the surface of the base material.　This resin plating material comprises: a base material that contains an insulating resin material; a microporous layer that is formed from the surface of the base material to a depth of 20 nm or more, contains voids having a nanometre order size, and supports a catalyst; and an electroless plating layer that is formed on the upper layer of the base material. A portion of the electroless plating layer enters the microporous layer, which is located in a region between the surface of the base material and a depth position of 20 nm or more from the surface of the base material.

Description

Resin-plated material and its manufacturing method

[0001] The present invention relates to a resin-plated product and a method for producing the same.

[0002] A wiring board having a wiring pattern formed on the surface of an insulating resin material is known. Conventionally, this wiring board is obtained by forming an electroless plating layer called a seed layer on the resin base material, and then forming an electrolytic plating layer on top of that.

[0003] To obtain stable electrical properties, the resin and the electroless plating layer (seed layer) must be firmly adhered to each other. A conventional method for improving adhesion involves roughening the surface of the resin to create irregularities, and then forming a seed layer on the irregular surface of the resin. The anchor effect resulting from the presence of irregularities firmly fixes the resin and seed layer together.

[0004] Incidentally, the 5G communication system, which has been under development in recent years, utilizes extremely high-frequency electrical signals. Such high-frequency currents flow only through the surface layer of the conductor, with difficulty flowing through the center of the conductor due to a phenomenon known as the skin effect. If the surface of the conductor is uneven, the signal transmission path becomes longer, resulting in increased transmission loss. Therefore, wiring boards, particularly 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 present inventors have proposed the techniques of Patent Documents 1 and 2 below.

[0006] JP 2023-080480 A JP 2023-080489 A

[0007] An object of the present invention is to provide a resin-plated product in which the adhesive strength between the substrate and the plating layer is improved compared to conventional products without providing substantial irregularities on the surface of the substrate, and to provide a method for producing such a resin-plated product.

[0008] The resin-plated product according to the present invention comprises a substrate containing an insulating resin material, a microporous layer formed from the surface of the substrate to a depth of 20 nm or more, containing voids of nanometer order size, and carrying a catalyst, and an electroless plating layer formed on the upper layer of the substrate, wherein a portion of the electroless plating layer penetrates into the microporous layer located in a region between the surface of the substrate and a depth of 20 nm or more from the surface of the substrate.

[0009] According to the above configuration, a portion of the electroless plating layer penetrates into the microporous layer formed in the surface region of the substrate to a depth of 20 nm or more, thereby creating a nano-level anchor effect between the substrate and the electroless plating 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 upper 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 progress 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 product with a TEM (transmission electron microscope).

[0013] However, if the depth of the region where the electroless plating layer penetrates into the microporous layer is too deep, when wiring is formed using this resin-plated material, a high proportion of 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 that is formed within the microporous layer is expected to have unevenness compared to the upper surface of the substrate, i.e., the region that is formed on the surface of the electroless plating layer. Therefore, when a high-frequency current is passed through it, a small amount of transmission loss may occur.

[0014] 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.

[0015] The microporous layer may be formed to a depth of 30 nm or more from the surface of the substrate.

[0016] This makes it easier to support the catalyst in the microporous layer during production.

[0017] As described above, the microporous layer is a layer containing voids generated by cleavage of some of the polymer chains of the resin material constituting the substrate. Therefore, if the thickness of the microporous layer is too large, the proportion of low-molecular-weight regions in the substrate increases, which may reduce the strength of the substrate itself.

[0018] From this viewpoint, the microporous layer may be formed in a region within a range between the surface of the substrate and a depth position of 200 nm or less from the surface of the substrate.

[0019] The method for manufacturing a resin-plated product according to the present invention is characterized by comprising the steps of: (a) preparing the substrate exhibiting thermosetting properties; (b) heating the substrate at a temperature higher than 100°C and lower than the glass transition temperature of the substrate; (c) irradiating the surface of the substrate with ultraviolet light having a dominant wavelength of 200 nm or less after the step (b), thereby forming voids of nanometer order size in the substrate over a depth region of 20 nm or more from the surface of the substrate, thereby forming the microporous layer in a portion of the substrate; (d) supporting the catalyst on the surface of the substrate and on the region of the substrate where the microporous layer is formed; and (e) forming an electroless plating layer on the surface of the substrate via the catalyst.

[0020] The strength of the substrate is increased by heating the substrate at a temperature higher than 100°C but lower than the glass transition temperature of the substrate. Then, ultraviolet light or a plasma-containing gas is irradiated to form a microporous layer near the surface of the substrate whose strength has been increased. Therefore, an electroless plating layer is then formed via the supported catalyst, and the electroless plating layer that has penetrated into the microporous layer is stably bonded to the substrate.

[0021] In particular, by heating the substrate at a temperature below the glass transition temperature, the substrate can be cured while maintaining the molecular network of the resin material that constitutes the substrate in a low-density state, and by subsequently irradiating it with ultraviolet light, the substrate can be modified not only on the surface but also to a certain depth, thereby ensuring the thickness of the microporous layer.

[0022] In this specification, the term "dominant wavelength" refers to the wavelength with the highest light intensity in the spectrum of light emitted from a light source.

[0023] The method for manufacturing a resin-plated product according to the present invention is characterized by comprising the steps of: (a) preparing the substrate; (b) heating the substrate at a temperature higher than 50°C and lower than the glass transition temperature of the substrate; (c) performing the step (b) and irradiating the surface of the substrate with ultraviolet light having a dominant wavelength of 200 nm or less to form voids of nanometer order size in the substrate over a depth region of 20 nm or more from the surface of the substrate, thereby forming the microporous layer in a portion of the substrate; (d) supporting the catalyst on the surface of the substrate and on the region of the substrate where the microporous layer is formed; and (e) forming an electroless plating layer on the surface of the substrate via the catalyst.

[0024] According to the above method, ultraviolet light is irradiated onto the substrate while heating it. Heating the substrate activates the molecular activity of the functional groups of the resin material that constitutes the substrate. When ultraviolet light is irradiated, the bonds of the molecules that constitute the resin material located on the surface are broken and the molecules are reduced in molecular weight, resulting in a replacement between the low molecular weight molecules present on the surface and the high molecular weight molecules present deeper than the surface. As a result, ultraviolet light is irradiated onto a large amount of the resin material in the depth direction of the substrate, allowing the microporous layer to be thickened.

[0025] Furthermore, since the microporous layer is heated while it is being formed, the strength of the microporous layer itself is improved, which in turn improves the adhesion between the subsequently formed electroless plated layer and the substrate.

[0026] If the heating temperature is low, such as below 50°C, the reaction will mainly occur with the side chains of the polymers constituting the resin material, rather than the main chains. In this case, even if ultraviolet light is irradiated while heating, voids will only be formed on the surface of the substrate, and the thickness of the microporous layer will not be ensured. From this perspective, heating is performed at a temperature higher than 50°C in step (b).

[0027] The step (a) may include a step of heating the substrate at a lower temperature than the step (b).

[0028] According to the above method, it is possible to remove in advance the residue of the organic solvent used in the production of the substrate.

[0029] According to the present invention, a resin-plated product is realized in which the adhesive strength between the substrate and the plating layer is improved compared to conventional products, without providing the substrate surface with substantial irregularities.

[0030] 5 is a cross-sectional view schematically showing the structure of a first embodiment of a resin-plated product of the present invention. FIG. 6 is a drawing schematically showing the structure of a microporous layer. FIG. 7 is a cross-sectional view schematically showing the structure of a resin-plated product including a patterned electrolytic plated layer. FIG. 8 is a drawing schematically showing the results of an elemental analysis by EDS of a cross-sectional image of the surface vicinity of a substrate included in the resin-plated product obtained using STEM-EDX. FIG. 9 is an example of the results of an element distribution analysis by EDS of a cross-sectional image of the surface vicinity of a substrate included in the resin-plated product obtained using STEM-EDX. FIG. 10 is a drawing showing the fitting of the results of FIG. 5 with a curve subjected to 10-point smoothing processing. FIG. 11 is a flowchart showing a manufacturing method of a first embodiment of a resin-plated product. FIG. 12 is a drawing schematically showing one step in the manufacturing method of a first embodiment of a resin-plated product. FIG. 13 is a drawing schematically showing one step in the manufacturing method of a first embodiment of a resin-plated product. FIG. 14 is a flowchart showing another manufacturing method of a second embodiment of a resin-plated product. 1 is a graph showing the results of mass spectrometry of substances with lower molecular weights than the constituent material of the substrate, performed by a TOF-SIMS method, for each of the samples of Example 1 and Example 5.

[0031] Embodiments of a resin-plated product and a method for manufacturing the same according to the present invention will be described below with reference to the accompanying drawings. The drawings are schematic illustrations, and the dimensional ratios in the drawings do not necessarily correspond to the actual dimensional ratios. Furthermore, the dimensional ratios between the drawings may not match each other.

[0032] First Embodiment A first embodiment of a resin-plated product and a method for producing the same according to the present invention will be described.

[0033] 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 substrate 3 and an electroless plating layer 9 formed on the +Z side surface of the substrate 3.

[0034] 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 a 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. Furthermore, 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.

[0035] In this embodiment, the base material 3 is an insulating and thermosetting resin material. Specific examples include polyimide resin, polyurethane, phenolic resin, and epoxy resin. The base material 3 may be a sheet-like film or a plate-like member.

[0036] The substrate 3 has a microporous layer 5 formed from the surface 3a of the substrate 3 to a depth D1. The microporous layer 5 is a layer formed by modifying the substrate 3, as described below. The depth D1 is 20 nm or more, more preferably 30 nm or more, and particularly preferably 70 nm or more. The depth D1 is preferably 190 nm or less.

[0037] FIG. 2 is a diagram schematically illustrating the structure of the microporous layer 5. The substrate 3 is formed of a polymeric resin material. As described below, 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. Oligomerization of the polymeric material forms spaces (voids 4) 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.

[0038] 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 effect (hereinafter referred to as a "catalytic compound"), and typically a substance containing Pd is used, but Ni, Ag, etc. can also be used.

[0039] 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 on top of 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.

[0040] 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.

[0041] As described above, the catalyst 7 is supported within the microporous layer 5. Therefore, at a position within the microporous layer 5, 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.

[0042] That is, with 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.

[0043] 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 product 1 shown in Fig. 1. After the electrolytic plated layer 11 has been formed on the top surface of the electroless plated layer 9 of the resin-plated product 1 shown in Fig. 1, a patterning step according to the wiring pattern is performed. As a result, a predetermined region A1 is etched in the depth direction, exposing the substrate 3.

[0044] Here, near the +Z side surface (surface 3 a) of substrate 3, electroless plated layer 9 penetrates into substrate 3, more specifically, into microporous layer 5. Therefore, during etching, the proportion of electroless plated layer 9 that is etched increases, and the amount of etching of substrate 3 made of a resin material can be reduced. As a result, a decrease in adhesion between substrate 3 and electroless plated layer 9 can be prevented when forming a wiring pattern.

[0045] 1 , the explanation will be continued. The thickness (i.e., depth D1) of the microporous layer 5 formed near the surface 3 a of the substrate 3 and the depth D2 to which the electroless plating layer 9 penetrates into the microporous layer 5 can both be confirmed by analyzing images of the resin-plated product 1 taken with a scanning transmission electron microscope (STEM). More specifically, these can be confirmed by photographing the resin-plated product 1 using an STEM equipped with an energy dispersive X-ray spectrometer (EDX) or an electron energy loss spectrometer (EELS) and understanding the change in elemental composition in the depth direction.

[0046] 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.

[0047] 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, in order to grow the electroless plating layer 9. Therefore, 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 results of the STEM-EDX analysis that the depth position corresponding to the peak value of the Pd signal intensity corresponds to the depth position on the surface 3a of the substrate 3. At this time, the electroless plating layer 9 is formed shallower than the surface 3a.

[0048] 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 the microporous layer 5 containing voids 4 for supporting Pd does not exist. 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.

[0049] 4, the presence of Cu signals is observed even deeper than the surface 3a of the substrate 3. This suggests that an electroless plating 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 plating layer 9 has penetrated into the substrate 3, more specifically, into the microporous layer 5 formed by modifying the substrate 3.

[0050] Within the microporous layer 5, the Cu signal intensity attenuates as the Cu signal advances in the depth direction, eventually reaching the detection limit. It can be inferred that the depth position at which the Cu signal reaches the detection limit is the position at which the formation of the electroless plated layer 9 has no longer 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 confirmed 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.

[0051] However, the detection limit 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 plating layer 9 embedded in the substrate 3 were determined by smoothing the results of elemental analysis using STEM-EDX at 10 points using a simple moving average method. Specifically, in the curves 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 plating layer 9 was determined from the depth position where the Pd signal intensity peaked to the position where the Cu signal intensity was 1% of the peak value. 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 at which the signal intensity was 2% of the peak value of the Pd signal intensity.

[0052] 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 a 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 shows a similar trend to the graph shown schematically in FIG. 4.

[0053] 6 is a graph in which the depth (thickness) D1 of the microporous layer 5 and the depth (thickness) D2 of the electroless plated layer 9 that penetrates into the substrate 3 are specified using the 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).

[0054] From the above viewpoint, in this specification, the thickness D1 of the microporous layer 5 and the thickness D2 of the electroless plated layer 9 penetrating into the substrate 3 are defined as values ​​measured for the resin-plated material 1 using the following method.

[0055] 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 the JEM-ARM200F (manufactured by JEOL Ltd.), but the apparatus is not limited to this example as long as it has a similar function.

[0056] More specifically, for example, the following method can be used. 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 an 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 is a graph obtained using this method.

[0057] 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.

[0058] Next, in the Cu curve obtained by the smoothing process, a position Cu1 showing the Cu peak value and a 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 by the thickness (Cu2 - Pd1) between the Pd peak position Pd1 and the Cu termination position Cu2.

[0059] 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%.

[0060] 7 is a flowchart showing an example of a method for manufacturing the resin-plated product 1 according to this embodiment. In the following description, the step numbers in FIG. 7 will be referred to as appropriate.

[0061] (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).

[0062] In step #1, the substrate 3 may be heated at a temperature lower than that in step #2 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.

[0063] (Step #2) Next, the substrate 3 is heated. The heating temperature is higher than 100°C and lower than the glass transition temperature of the resin material that constitutes the substrate 3. The heating temperature is preferably lower than 160°C. A typical example of heating conditions is 140°C for 30 minutes.

[0064] Step #2 increases the hardness of the resin that constitutes 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.

[0065] As a specific embodiment of step #2, for example, the substrate 3 may be placed in a chamber including a heater and heated for a predetermined time. Alternatively, the substrate 3 may be placed on the upper surface of a stage equipped with a heating mechanism for a predetermined time.

[0066] This step #2 corresponds to process (b).

[0067] (Step #3) Next, as shown in Fig. 9, the substrate 3 is irradiated with ultraviolet light L1 having a dominant wavelength of 200 nm or less. In this embodiment, the light source of the ultraviolet light L1 is arbitrary, but is preferably a Xe excimer lamp. As another example, the light source may be a solid-state light source such as an LED or laser diode that can emit ultraviolet light L1 having a dominant wavelength of 200 nm or less.

[0068] 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 air atmosphere, part of the ultraviolet light L1 is absorbed by O2 in the air, and the ground state atomic oxygen O( 3 P) is generated. The left side of equation (1) conveniently expresses the absorption of ultraviolet light with wavelength λ by O2, and μ indicates the frequency of wavelength λ. O2 + hν → 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 formula (2): O( 3 P) + O2 → O3 (2)

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

[0071] When ultraviolet light L1 is irradiated onto the surface 3a of the substrate 3, part of the ultraviolet light L1 is absorbed by oxygen in the atmosphere present 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. C m 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 3 a of the substrate 3, modifying it into low-molecular-weight oligomers. As a result, the region near the surface 3 a of the substrate 3 is modified into a microporous layer 5 containing voids 4, as described above with reference to FIG.

[0074] As described above, in step #2, the substrate 3 is heated in advance. Moreover, the heating temperature is lower than the glass transition temperature of the substrate 3. As a result, the substrate 3 is cured while maintaining the molecular network of the resin material constituting the substrate 3 in a low-density state. Then, by irradiating the substrate 3 with ultraviolet light L1, the substrate 3 can be modified into a microporous layer 5 not only on the surface 3a of the substrate 3 but also from the surface 3a to a depth D1.

[0075] This step #3 corresponds to process (c).

[0076] (Step #4) Next, the 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.

[0077] In step #3, a microporous layer 5 containing voids 4 is formed on the substrate 3 from the surface 3a to a depth 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.

[0078] This step #4 corresponds to process (d).

[0079] (Step #5) Next, as shown in Fig. 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.

[0080] Through this process, an electroless plating 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 plating layer 9 also grows within the microporous layer 5. As a result, part of the electroless plating layer 9 penetrates into the interior of the substrate 3, more specifically, into the microporous layer 5.

[0081] This step #5 corresponds to process (e).

[0082] (Post-Processing) After that, post-processing is carried out, including the step of forming electrolytic plated layer 11 on top of electroless plated layer 9 .

[0083] [Second Embodiment] A second embodiment of the resin-plated product and its manufacturing method according to the present invention will be described, focusing on differences from the first embodiment. Fig. 11 is a flowchart showing an example of a manufacturing method of the resin-plated product 1 according to the second embodiment, following the example of Fig. 7.

[0084] In comparison with the first embodiment, this embodiment has the same structure as the resin-plated product 1, but the manufacturing method thereof is different.

[0085] (Step #1) As in the first embodiment, the substrate 3 is prepared. In this embodiment, the material of the substrate 3 is not limited to a thermosetting resin as long as it is a resin that exhibits insulating properties. 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.

[0086] (Step #6) Next, the substrate 3 is irradiated with ultraviolet light L1 while being heated. For example, the substrate 3 is placed on a stage including a heating mechanism, and ultraviolet light L1 from a light source is irradiated onto the substrate 3. As another example, the substrate 3 may be placed in a chamber that houses a heater and a light source, and heating of the substrate 3 and irradiation of the ultraviolet light L1 may be performed in parallel within the chamber.

[0087] In step #6, the heating temperature is higher than 50°C and lower than the glass transition temperature of the resin material constituting the substrate 3. The heating temperature is preferably lower than 160°C. An example of a typical heating condition is 100°C for 30 minutes. The heating time may be changed as appropriate depending on the type of resin material, and may be, for example, about 1 minute.

[0088] This step #6 modifies the substrate 3 into a microporous layer 5 from the surface 3a to a depth D1. In particular, irradiation with ultraviolet light L1 while heating activates the molecular activity of the functional groups of the resin material constituting the substrate, facilitating exchange between low-molecular-weight molecules present at the surface 3a and high-molecular-weight molecules present at positions deeper than the surface 3a. As a result, ultraviolet light L1 is irradiated onto a larger portion of the resin material in the depth direction, increasing the thickness of the microporous layer 5. Furthermore, this fragile microporous layer 5 can be hardened, which also has the effect of improving adhesion between the substrate 3 and the electroless plating layer 9.

[0089] If the heating temperature is set to less than 50°C, the reaction will mainly occur with the side chains of the polymers constituting the resin material, rather than the main chains. In this case, even if ultraviolet light is irradiated while heating, voids will only be formed on the surface of the substrate, making it difficult to ensure the thickness of the microporous layer 5. From this perspective, the heating temperature is set to a temperature higher than 50°C.

[0090] This step #6 corresponds to the steps (b) and (c). Note that the steps performed after the end of step #6 are the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0091] [Another embodiment] As described above, the resin-plated product 1 includes a substrate 3, a microporous layer 5 formed from the surface 3a of the substrate 3 to a depth D1 of 20 nm or more, and an electroless plating layer 9 formed on the substrate 3, with a portion of the electroless plating layer 9 extending into the microporous layer 5 to a depth D2 of 20 nm or more. The present invention covers a resin-plated product 1 having such a structure, but its manufacturing method is not limited to the above. For example, in the first embodiment, step #2, which corresponds to the heating step, can be omitted by increasing the irradiance of the ultraviolet light L1 in step #3. However, to accurately manufacture the resin-plated product 1, it is preferable to perform step #2 or step #6, which corresponds to the heating step.

[0092] Specific examples will be shown below to explain the present invention in more detail, but the present invention is not limited to these examples.

[0093] (Verification 1: Adhesion Strength) A number of samples were produced in which the depth to which the electroless plated layer 9 penetrated into the microporous layer 5 was varied, and the adhesion strength of each was measured.

[0094] Example 1 A COP resin (100 μm ZeonorFilm (registered trademark), manufactured by Nippon Zeon Co., Ltd.) defined by the following formula (5) was prepared as a sample of the substrate 3. The resin was irradiated with light at an illuminance of 1,200 mJ / cm using a light irradiation device (SVC 232 Series, manufactured by Ushio Inc., peak wavelength 172 nm). 2 The surface of the substrate 3 was irradiated with ultraviolet light for 60 seconds.

[0095]

[0096] The substrate 3 was then immersed in a conditioner solution M1 to perform a degreasing treatment and adjust the surface potential of the substrate 3 to a cation. After a water rinse, the substrate 3 was immersed in a catalyst imparting solution M3 to impart a catalyst complex to the surface of the substrate 3. After a water rinse, the substrate 3 was immersed in an activation treatment solution M4 to reduce the catalyst complex to a metal. After a water rinse, the substrate 3 was immersed in an electroless metal plating solution M5 to reduce the metal ions via the catalyst, thereby forming an electroless plating layer 9 on the substrate 3.

[0097] When the substrate 3 was immersed 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.

[0098] The chemical solutions used were as follows: Conditioner solution M1: PB-102 and EC-B (both manufactured by JCU Corporation) Catalyst application solution M3: A mixture of AISL-ACT (manufactured by JCU Corporation) and hydrochloric acid Activation treatment solution M4: A mixture of PCBA and PB-570B (both manufactured by JCU Corporation) Electroless metal plating solution M5: A mixture of PCBA, PB-570MU, PB-570B, and PB-570C (all manufactured by JCU Corporation)

[0099] For samples in which an electroless plating layer 9 was formed on a substrate 3, the thickness D1 of the microporous layer 5 and the thickness D2 of the electroless plating layer 9 penetrating into the microporous layer 5 were determined using the method described above with reference to Figures 5 and 6.

[0100] In addition, a stud pin was attached to the surface of the electroless plating layer 9 and pulled at a constant load rate to measure the adhesion strength of the sample using a method conforming to the stud pull peel strength test method (MIL-SID-883). The adhesion strength was 400 kg / cm 2 ] or above is rated A, 120 [kg / cm 2 ] or more 400[kg / cm 2 ] or less is rated B, 120 [kg / cm 2 ] or less was rated as C.

[0101] (Example 2) UV irradiance: 1,800 mJ / cm 2 A sample was prepared in the same manner as in Example 1, except for the above, and the thickness D1 of the microporous layer 5, the thickness D2 of the electroless plated layer 9 that had penetrated into the microporous layer 5, and the adhesion strength were measured.

[0102] (Comparative Example 1) UV irradiance: 500 mJ / cm 2A sample was prepared in the same manner as in Example 1, except for the above, and the thickness D1 of the microporous layer 5, the thickness D2 of the electroless plated layer 9 that had penetrated into the microporous layer 5, and the adhesion strength were measured.

[0103] (Example 3) A sample was prepared in the same manner as in Example 2, except that the substrate 3 was heated to 100°C using a heater while being irradiated with ultraviolet light L1, and the thickness D1 of the microporous layer 5, the thickness D2 of the electroless plating layer 9 penetrating into the microporous layer 5, and the adhesion strength were each measured.

[0104] (Examples 4 to 6) Samples were prepared using the same method as in Example 3, with the illuminance of ultraviolet light L1 varied, and the thickness D1 of the microporous layer 5, the thickness D2 of the electroless plating layer 9 that had penetrated into the microporous layer 5, and the adhesion strength were measured.

[0105] (Example 7) A liquid crystal polymer resin defined by the following formula (3) was used as a sample of the substrate 3. The illuminance of ultraviolet light was 500 mJ / cm 2 A sample was prepared in the same manner as in Example 1, except that the following chemical solutions were used in each treatment, and the substrate 3 was immersed in a pre-dip solution M2 before being immersed in a catalyst application solution M3 to adjust the surface potential of the substrate 3 to anion, and the thickness D1 of the microporous layer 5, the thickness D2 of the electroless plating layer 9 penetrating into the microporous layer 5, and the adhesion strength were each measured.

[0106] The chemical solutions used were as follows: Conditioner solution M1: Top LECS Conditioner (manufactured by Okuno Pharmaceutical Industries Co., Ltd.) Pre-dip solution M2: Top LECS Pre-dip M (manufactured by Okuno Pharmaceutical Industries Co., Ltd.) Catalyst application solution M3: Mixed solution of Top LECS Catalyst A and Top LECS Catalyst C (both manufactured by Okuno Pharmaceutical Industries Co., Ltd.) Activation treatment solution M4: Mixed solution of Top LECS Accelerator (manufactured by Okuno Pharmaceutical Industries Co., Ltd.) and boric acid Electroless metal plating solution M5: Mixed solution of Top LECS Copper A, Top LECS Copper M, Top LECS Copper C and Electroless Copper RN (all manufactured by Okuno Pharmaceutical Industries Co., Ltd.)

[0107]

[0108] (Comparative Example 2) UV irradiance: 200 mJ / cm 2 A sample was prepared in the same manner as in Example 7, except for the above, and the thickness D1 of the microporous layer 5, the thickness D2 of the electroless plated layer 9 that had penetrated into the microporous layer 5, and the adhesion strength were measured.

[0109] (Results) The results are shown in Table 1.

[0110]

[0111] According to Table 1, it is confirmed that in Examples 1 to 7, in which the thickness D2 of the electroless plated layer 9 penetrating into the microporous layer 5 is 20 nm or more, the adhesion strength between the substrate 3 and the electroless plated layer 9 is increased compared to Comparative Examples 1 and 2, in which the thickness D2 is 5 nm. In particular, it is confirmed that in Examples 3 to 6, in which the thickness D2 is 35 nm or more, the adhesion strength between the substrate 3 and the electroless plated layer 9 is further increased.

[0112] In particular, when comparing Example 2 and Example 3, the adhesion strength of the former is 220 kg / cm 2 The adhesive strength of the latter was 400 kg / cm 2 This is thought to be due not only to the magnitude of thickness D2 but also to the fact that the heating step performed in producing the sample of Example 3 improved the strength of microporous layer 5 itself, allowing electroless plated layer 9 to penetrate into microporous layer 5 with improved strength.

[0113] (Verification 2: Effect of introducing oxygen functional groups by heating) When the substrate 3 is irradiated with ultraviolet light L1, as described above, some of the polymer chains that make up the substrate 3 are cleaved, and low-molecular-weight substances are secondarily produced. For this reason, it is expected that by performing mass analysis using TOF-SIMS on the substrate 3 after irradiation with ultraviolet light L1, substances different from the polymer material that makes up the substrate 3 will be detected. Furthermore, if the ultraviolet light L1 reaches only the vicinity of the surface 3a of the substrate 3, it is expected that low-molecular-weight substances will be detected only in this region.

[0114] For the sample of Example 1, which was irradiated with ultraviolet light L1 without heating, and the sample of Example 5, which was irradiated with ultraviolet light L1 while being heated to 100°C, mass analysis was performed by TOF-SIMS while sputtering the surface of the substrate 3 with an Ar gas cluster ion beam (Ar-GCIB). Both sputtering and mass analysis were performed using a TOF.SIMS5 manufactured by ION-TOF. For mass analysis, normalization was performed using the spectral intensity of CHO, which is presumed to be obtained by cleavage of some molecular chains of the COP resin defined by formula (5). The results are shown in Figure 12.

[0115] 12, signals derived from CHO are observed at extremely deep positions in Example 5 compared to Example 1. This confirms that by irradiating the substrate with ultraviolet light L1 while heating, oxygen functional groups are introduced even in regions extending significantly in the depth direction from the surface 3a of the substrate 3. This suggests that the thickness D1 of the microporous layer 5 can be increased by irradiating the substrate with ultraviolet light L1 while heating.

[0116] Furthermore, based on the above verification, it is inferred that the thickness D1 of the microporous layer 5 can be increased not only by performing ultraviolet light L1 and heating in parallel, but also by the method described above in the first embodiment, in which ultraviolet light L1 is irradiated after heating.

[0117] REFERENCE SIGNS LIST 1: Resin plated material 3: Base material 3a: Surface of base material 4: Void 5: Microporous layer 7: Catalyst 9: Electroless plated layer 11: Electrolytic plated layer L1: Ultraviolet light

Claims

1. A resin plated product comprising: a substrate containing an insulating resin material; a microporous layer formed to a depth of 20 nm or more from the surface of the substrate, containing voids of nm order size, and carrying a catalyst; and an electroless plating layer formed on the upper layer of the substrate, wherein a portion of the electroless plating layer penetrates into the microporous layer located in a region between the surface of the substrate and a depth of 20 nm or more from the surface of the substrate.

2. The resin-plated product according to claim 1, wherein the depth range of the region where part of the electroless plating layer penetrates into the microporous layer is 100 nm or less.

3. The resin-plated product according to claim 1 or 2, wherein the microporous layer is formed to a depth of 30 nm or more from the surface of the base material.

4. A resin-plated product as described in claim 1 or 2, characterized in that the microporous layer is formed in a region within a range from the surface of the base material to a depth position of 190 nm or less from the surface of the base material.

5. A method for producing a resin-plated product as described in claim 1, comprising the steps of: (a) preparing the substrate exhibiting thermosetting properties; (b) heating the substrate at a temperature higher than 100°C and lower than the glass transition temperature of the substrate; (c) irradiating the surface of the substrate with ultraviolet light having a dominant wavelength of 200 nm or less after the step (b), thereby forming voids of a size on the order of nm in the substrate over a depth region of 20 nm or more from the substrate surface, thereby forming the microporous layer in a portion of the substrate; (d) supporting the catalyst on the substrate surface and on the region of the substrate where the microporous layer is formed; and (e) forming an electroless plating layer on the substrate surface via the catalyst.

6. A method for producing a resin-plated product as described in claim 1, comprising the steps of: (a) preparing the substrate; (b) heating the substrate at a temperature higher than 50°C and lower than the glass transition temperature of the substrate; (c) which is carried out in conjunction with the step (b), irradiating the surface of the substrate with ultraviolet light having a dominant wavelength of 200 nm or less to form voids of a size on the order of nm in the substrate over a depth region of 20 nm or more from the substrate surface, thereby forming the microporous layer in a portion of the substrate; (d) supporting the catalyst on the substrate surface and on the region of the substrate where the microporous layer is formed; and (e) forming an electroless plating layer on the substrate surface via the catalyst.

7. The method for producing a resin-plated product according to claim 5, wherein the step (a) includes a step of heating the base material at a lower temperature than the step (b).

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