Method for manufacturing resin plating material, and electroless plating apparatus

Abstract

To provide a method for manufacturing a resin plating material with controllability higher than a conventional method without substantially providing unevenness on the surface of a base material.SOLUTION: A method for manufacturing a resin plating material includes: a step (a) of preparing a base material having an insulating resin material; a step (b) of irradiating the surface of the base material with ultraviolet light of a wavelength of 200 nm or less in the atmosphere having an oxygen concentration of 0.01-10 vol.%, and modifying a treatment object region containing the surface of the base material into a microporous layer having a gap of a nm order; a step (c) of coupling a catalyst to the microporous layer; and a step (d) of forming an electroless plating layer on the upper surface of the base material through the catalyst after the step (c).SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a resin-plated material, which is obtained by forming a plating on a substrate containing a resin material. The present invention also relates to an electroless plating apparatus suitable for manufacturing such a resin-plated material. [Background technology]

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

[0003] To obtain stable electrical properties, the resin and the seed layer must be firmly bonded. Conventionally, a method has been known to improve adhesion by roughening the surface of the resin to create irregularities, and then forming the seed layer on the surface of the resin where the irregularities have been formed. The resin and the seed layer are firmly fixed together by the anchoring effect resulting from the presence of the irregularities.

[0004] Incidentally, the 5G communication system, which has been under development in recent years, utilizes extremely high-frequency electrical signals. Due to a phenomenon called the skin effect, such high-frequency currents flow less easily through the center of a conductor and only flow through the surface layer. If there are irregularities on the surface of the conductor, the signal transmission path becomes longer, resulting in increased transmission loss. Therefore, wiring boards that are intended to handle particularly high-frequency signals are required to have as few irregularities as possible on the surface of the conductors.

[0005] Patent Document 1, described below, describes a method of finely roughening a resin material by irradiating it with ultraviolet light in an oxygen atmosphere, using ultraviolet light and ozone. This method is said to be able to roughen the material more finely than the conventional roughening method known as desmear treatment. [Prior art documents] [Patent Documents]

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, as a result of the verification by the present inventors, it has been found that the base material containing the resin material is easily embrittled according to the method of Patent Document 1. In other words, in the case of the method of Patent Document 1, extremely delicate control is required to modify the surface without embrittling the base material, so there are practical problems.

[0008] An object of the present invention is to provide a method for producing a resin plating material in which a plating material is applied to a resin by a method that is substantially free of unevenness on the surface of the base material and has higher controllability than conventional methods. Another object of the present invention is to provide an electroless plating apparatus suitable for use in this method.

Means for Solving the Problems

[0009] The method for producing a resin plating material according to the present invention includes: step (a) of preparing a base material containing an insulating resin material; step (b) of irradiating the surface of the base material with ultraviolet light having a wavelength of 200 nm or less in an atmosphere having an oxygen concentration of 0.01% by volume to 10% by volume to modify a treatment target region including the surface of the base material into a microporous layer containing voids having a size on the order of nm; step (c) of bonding a catalyst to the microporous layer; and having step (d) of forming an electroless plating layer on the upper surface of the base material via the catalyst after step (c).

[0010] Regarding the reason why the base material is easily embrittled by the method described in Patent Document 1, the present inventors推测 as follows.

[0011] When forming a plating layer on the upper surface of a substrate, it is important to improve the adhesion between the substrate and the plating layer. The challenge of improving adhesion between the substrate and the layer above it is common whether an adhesive layer (adhesive sheet) is formed on top of the substrate or a plating layer is formed on top of the substrate. With this background in mind, the following will first explain the challenges that may arise when forming an adhesive sheet on top of a substrate.

[0012] Conventionally, when a resin substrate is irradiated with ultraviolet light, it was believed that the contact angle of the substrate surface would decrease monotonically with increasing ultraviolet light exposure, as schematically shown in Figure 1. A smaller contact angle means that the adhesive strength between the substrate and another layer would increase when another layer is bonded to the substrate surface. Therefore, as schematically shown in Figure 2, it was believed that the adhesive strength would increase monotonically with increasing ultraviolet light exposure.

[0013] In other words, it was believed that stably adhering another layer to the surface of a substrate could be achieved by irradiating the substrate with an ultraviolet radiation dose greater than the point where the curve showing the change in contact angle shows an inflection point, that is, an irradiation dose greater than or equal to Q1 in Figure 1.

[0014] However, through diligent research by the inventors, when measuring the relationship between irradiation dose and adhesive strength while irradiating the substrate with ultraviolet light in an atmospheric environment, it was confirmed that as the irradiation dose increased, the adhesive strength tended to decrease after reaching a peak value, as shown in Figure 3. Figure 3 is a schematic graph newly confirmed by the inventors, showing the relationship between the amount of ultraviolet light irradiated onto the substrate and the adhesive strength between the substrate surface and other layers.

[0015] In other words, as shown in Figure 3, it is necessary to adjust the amount of ultraviolet light irradiation within a limited range (Qr1) in order to impart high adhesive strength to the surface of the substrate.

[0016] Figure 4 shows the relationship between UV irradiation time and the contact angle on the substrate surface, and the relationship between the irradiation time and adhesive strength, measured and graphed by irradiating the surface of a substrate with ultraviolet light at a predetermined intensity in an atmospheric environment. In Figure 4, the horizontal axis represents UV irradiation time, the left vertical axis represents adhesive strength, and the right vertical axis represents the contact angle. Figure 4 is a graph created based on the results measured using the following method.

[0017] Polyimide resin (Kapton 100EN-C, manufactured by Toray DuPont) was prepared as a substrate sample (Kapton is a registered trademark of the company). Ultraviolet light was irradiated onto the surface of this sample from a distance (separation) of 3 mm using an ultraviolet irradiation device (SVC 232 Series, peak wavelength 172 nm, manufactured by Ushio Inc.).

[0018] After irradiating each sample with ultraviolet light for varying irradiation times, the contact angle of the sample surface was measured using a contact angle measuring device (DMo-501, manufactured by Kyowa Interface Science Co., Ltd.).

[0019] Next, each sample was irradiated with ultraviolet light for varying irradiation times. Then, the irradiated surfaces of the same samples were bonded together using an adhesive sheet (Aron Mighty AF-700, manufactured by Toagosei Co., Ltd.) and laminated at 100°C (Aron Mighty is a registered trademark of the same company). Subsequently, a compression treatment was performed at 180°C for 30 minutes while pressing with a pressure of 2 MPa to 3 MPa. The adhesive strength of the bonded samples obtained after compression was measured according to the method conforming to JIS K 6854-3 (Adhesives - Test methods for peel adhesion strength Part 3: T-type peel). However, in Figure 4, the adhesive strength is shown as a relative value.

[0020] As shown in Figure 4, the graph illustrating the relationship between adhesive strength and irradiation time confirms that, above the peak value, the adhesive strength tends to decrease as the irradiation time increases. When the ultraviolet irradiance is constant, the irradiation time is proportional to the irradiation amount. In other words, Figure 3 schematically illustrates the trend shown in Figure 4.

[0021] The results in Figures 3 and 4 show that when irradiating a substrate with ultraviolet light using conventional methods, the conditions for irradiation doses that exhibit high adhesive strength are extremely limited. In other words, high adhesive strength cannot be achieved unless the amount of ultraviolet light irradiation is controlled with extremely high precision. As shown in Figure 4, it can be understood that the adhesive strength decreases even if the irradiation time is extended by only 1 to a few seconds. However, while the relationship between adhesive strength and irradiation time (irradiation dose) as shown in Figure 4 shows a narrow range of peak values, which is common to all resins, the actual optimal irradiation dose differs depending on the resin. As a result, the substrate is irradiated with ultraviolet light exceeding the optimal dose, leading to low adhesive strength on the substrate surface.

[0022] On the other hand, if you try to adjust the irradiation time so as not to exceed the desired irradiation dose, it may result in not reaching the irradiation dose necessary for the adhesive strength to reach its peak value. In this case as well, it is not possible to impart high adhesive strength to the substrate.

[0023] The above explanation assumed the case where an adhesive sheet is formed on the upper surface of the substrate. However, when irradiating the surface of the substrate with ultraviolet light to achieve high adhesion when forming a plating layer on the upper surface of the substrate, it is understood that the same problems as when forming an adhesive sheet may arise. In other words, when attempting to irradiate the substrate with ultraviolet light to form a plating layer on the upper surface of the substrate, there is a concern that the adhesive strength of the substrate surface will decrease if the ultraviolet light is irradiated to the substrate in an amount exceeding the desirable amount. Conversely, if one attempts to adjust the irradiation time so as not to exceed the desirable amount, it may result in not reaching the irradiation amount necessary for the adhesive strength to reach its peak value.

[0024] Figure 5 is a graph showing the absorption spectra of oxygen (O2) and ozone (O3). For reference, the emission spectrum of a Xe excimer lamp is superimposed in Figure 5. In Figure 5, the horizontal axis represents wavelength, the left vertical axis represents the relative light intensity of the excimer lamp, and the right vertical axis represents the absorption coefficients of oxygen (O2) and ozone (O3).

[0025] Patent Document 1 states that, regarding the wavelength of ultraviolet light, 150nm to 400nm is preferred, 150nm to 350nm is more preferred, and 150nm to 300nm is even more preferred. According to the example in Patent Document 1, an ultraviolet irradiation device (SSP-16: manufactured by Sen Special Light Source Co., Ltd.) is used for surface treatment of the resin, and it is clear from the company's catalog that this light source exhibits peak emission spectral values ​​at 185nm and 254nm. From this, it can be understood that Patent Document 1 plans to use a low-pressure mercury lamp as a light source for surface treatment of the substrate.

[0026] Low-pressure mercury lamps emit ultraviolet light with extremely short peak wavelengths of half-width near 185 nm and 254 nm. As shown in Figure 5, ultraviolet light near 185 nm is readily absorbed by oxygen. Therefore, when ultraviolet light from a low-pressure mercury lamp is irradiated onto a resin substrate in an atmospheric environment, some of the ultraviolet light is absorbed by oxygen in the atmosphere, and the ground state atomic oxygen O(O) is released according to equation (1) below. 3 P) is generated. O2+ hν (185nm) → O( 3 P) + O( 3 P) ... (1)

[0027] This atomic oxygen O( 3 P) reacts with oxygen (O2) in the atmosphere to produce ozone (O3) according to equation (2) below. O( 3 P) + O2 → O3 (2)

[0028] As shown in Figure 5, ozone (O3) exhibits the property of absorbing ultraviolet light. When ultraviolet light from a low-pressure mercury lamp is absorbed by ozone (O3), the atomic oxygen in the excited state is expressed according to equation (3) below. 1 D) is generated. O3+ hν (185nm, 254nm) → O2+ O( 1 D) ... (3)

[0029] Atomic oxygen O( 1D) is extremely reactive. Therefore, it acts on the polymer (C m H n O k ) that constitutes the base material, cutting the molecular chains. In the following formula (4), m, m', n, n, k, and k' are all integers, and m > m', n > n', and k > k'. However, it should be noted that formula (4) schematically shows the reaction and is different from an exact chemical reaction formula. C m H n O k + O( 1 D) → H2O, CO, CO2+ C m' H n' O k' ···(4)

[0030] The polymer (C m H n O k ) that constitutes the resin and the intermediate products generated by the reaction of formula (4) are also partially cleaved by direct irradiation with ultraviolet light in addition to the action of O( 1 D).

[0031] Since the ultraviolet light emitted from a low-pressure mercury lamp contains a long-wavelength component of 254 nm, the ultraviolet light is more likely to penetrate into the base material in the depth direction than the short-wavelength component of 200 nm or less. Therefore, as shown in FIG. 6, a part of the ultraviolet light L90 from the low-pressure mercury lamp 90 travels in the depth direction with respect to the base material 3. That is, energy derived from the ultraviolet light L90 is input to the region from the surface 3a of the base material 3 to the location that has traveled d90 in the depth direction.

[0032] Then, due to the above circumstances, the ultraviolet light L90 itself or the highly reactive O( 1 D) obtained in formula (3) acts on a sufficiently deep location from the surface 3a of the base material 3. As a result, in a sufficiently deep location from the surface 3a of the base material 3, the polymer (C m H n O kThe bonds between the molecules are broken, resulting in a breakdown into smaller molecules. As a result, the smaller molecular chains overlap, which is thought to weaken the substrate 3.

[0033] Figure 7 is a schematic diagram showing the molecular chains of the polymer material constituting the substrate 3. As described above, in the deeper parts of the substrate 3, ultraviolet light and mainly O( 1 When D) acts on the material, the molecular chain is cleaved at many points, generating low-molecular-weight substances (see Figure 8). Figure 8 schematically illustrates the state in which the constituent material of substrate 3 shown in Figure 7 is cleaved and reduced to low molecular weight.

[0034] In other words, the ultraviolet L90 emitted from a low-pressure mercury lamp has wavelength components of 185 nm and 254 nm. While this modifies the surface 3a of the substrate 3, the longer wavelength components cause damage to the substrate 3 in the depth direction. As a result, the strength of the substrate 3 decreases.

[0035] Therefore, the inventors considered using a xenon (Xe) excimer lamp, which emits ultraviolet light with fewer wavelength components above 200 nm, as a light source instead of a low-pressure mercury lamp, and irradiating the substrate with ultraviolet light from the said light source. However, as described above and shown in Figure 4, the amount of ultraviolet light that can impart high adhesive strength to the substrate is limited.

[0036] The inventors considered that the limited amount of ultraviolet irradiation required to impart high adhesive strength to the substrate is due to the extremely rapid reaction. In particular, in the case of ultraviolet light with a peak wavelength of less than 185 nm, such as that from a Xe excimer lamp (peak wavelength around 172 nm), when a portion of it is absorbed by oxygen in the atmosphere, the excited atomic oxygen O(O) is released according to equation (5) below. 1 D) is generated. O2+ hν (172nm) → O( 1 D) + O( 3 P) ... (5)

[0037] Note that the atomic oxygen obtained by equation (5) O( 3 As described above, a portion of P is converted to excited atomic oxygen O( through equations (2) and (3)). 1 It changes to D).

[0038] In other words, the shorter the wavelength of the ultraviolet light irradiated onto the substrate, the more the reaction occurs only on the surface of the substrate, resulting in almost no damage in the depth direction, and the more reactive O( 1 The rate of D) formation is increased. Therefore, it is thought that the rate of cleaving the molecular chains of the polymer material constituting the substrate is increased.

[0039] To efficiently modify the surface of the substrate, it is preferable to cleave only the molecular chains of the polymer material present near the surface of the substrate, thereby creating voids. This is because, when a catalyst is subsequently applied to adhere other layers, compounds containing molecules or atoms that exhibit a catalytic effect (hereinafter referred to as "catalyst-contributing compounds") can be introduced into these voids. However, as described above, if the reaction that cleaves the molecular chains of the polymer material proceeds at high speed, the same phenomenon occurs not only on the surface of the substrate but also in deeper regions, weakening the substrate. In other words, the limited irradiation dose that can impart high adhesive strength to the substrate, as described above with reference to Figures 3 and 4, is an irradiation dose sufficient to cleave only the molecular chains of the polymer material present near the surface of the substrate.

[0040] In the method according to the present invention, the atmosphere irradiated with ultraviolet light is set to 0.01% to 10% by volume, resulting in an extremely low oxygen concentration compared to the atmosphere. As a result, the above O( 1 Because the generation rate of D) is reduced, the range of irradiation doses that can impart high adhesive strength to the substrate is expanded, increasing the degree of control and improving controllability. Here, "control" refers to the control performed to realize a production process that can obtain stable adhesive strength (plating strength).

[0041] Figure 9 is a schematic graph, following Figure 3, showing the relationship between the amount of ultraviolet radiation irradiated onto the substrate and the adhesive strength between the substrate surface and other layers, under conditions of low oxygen concentration. For comparison, Figure 9 also includes a graph showing the results under atmospheric conditions.

[0042] As shown in Figure 9, when the atmosphere is at a low oxygen concentration, the range of ultraviolet irradiation doses (Qr2) that can impart high adhesive strength to the substrate surface is significantly wider compared to the case of an atmospheric environment (Qr1). When ultraviolet irradiation is performed within this range (Qr2), polymer chains near the surface of the substrate are broken, and voids are formed. In other words, only the area near the surface of the substrate is modified into a layer containing voids (microporous layer).

[0043] Figure 10 shows the relationship between UV irradiation time and the contact angle on the substrate surface, and the relationship between irradiation time and adhesive strength, measured and graphed after irradiating the substrate surface with ultraviolet light at a predetermined intensity under a low-oxygen atmosphere. The graphing method is the same as in Figure 4, except that the oxygen concentration of the atmosphere is different. In Figure 10, the oxygen concentration of the atmosphere was set to 0.1 volume% (1000 ppm).

[0044] As shown in Figure 10, even when UV irradiation is extended by several tens to a hundred seconds compared to the irradiation time at which the adhesive strength peaks, the adhesive strength does not decrease significantly compared to Figure 4. In other words, Figure 10 schematically illustrates the trend shown in Figure 9.

[0045] Figure 11 is a schematic diagram, following Figure 6, showing the propagation of ultraviolet light L10 when ultraviolet light L10 from the Xe excimer lamp 10 is irradiated onto the substrate 3. The ultraviolet light L10 from the Xe excimer lamp 10 has a peak wavelength near 172 nm. As shown in Figure 11, the ultraviolet light L10 propagates a distance d10 in the depth direction from the surface of the substrate 3. The ultraviolet light L10 from the Xe excimer lamp 10 has a shorter wavelength band than the ultraviolet light L90 emitted from the low-pressure mercury lamp. Therefore, the distance d10 is extremely short compared to the propagation distance d90 (Figure 6) when ultraviolet light L90 from the low-pressure mercury lamp 90 is irradiated. In other words, the ultraviolet light L10 acts only near the surface of the substrate 3.

[0046] By setting the atmosphere 1, to which ultraviolet light L10 is irradiated, to a low oxygen concentration, the range of ultraviolet light L10 irradiation doses that can impart high adhesive strength to the surface 3a of the substrate 3 is expanded, as described above. When ultraviolet light L10 is irradiated to the surface 3a of the substrate 3 at such doses, only a portion of the polymer chains constituting the substrate 3 is cleaved and oligomerized. At this time, spaces (voids 4) are formed between the oligomers (see Figure 12). Figure 12 schematically illustrates, following Figure 8, how a portion of the polymer chains constituting the substrate 3 is cleaved and voids 4 are formed.

[0047] In other words, according to the methods of carrying out steps (a) and (b) above, voids 4 are formed near the surface 3a of the substrate 3. Therefore, by subsequently performing step (c) in which the catalyst is applied, the catalyst-contributing compound can be introduced into the voids 4 without roughening the surface 3a of the substrate 3. Consequently, by subsequently performing step (d) in which an electroless plating layer is formed, an electroless plating layer with high adhesion to the surface 3a of the substrate 3 is formed.

[0048] In other words, in this specification, the "microporous layer" is a layer containing voids 4 created by the cleavage of a portion of the polymer chains constituting the substrate 3, and these voids 4 are on the order of nanometers (1 nm to several nanometers).

[0049] The presence and thickness of the microporous layer can be confirmed by observing a cross-section using a TEM (transmission electron microscope) after adhering another layer to the surface of the substrate. Further details will be described later.

[0050] The above explanation uses the case where the peak wavelength of ultraviolet light is around 172 nm as an example, but a similar explanation is possible for wavelengths below 200 nm. In the case of ultraviolet light with wavelengths longer than 172 nm and below 200 nm, atomic oxygen (O()) is present compared to ultraviolet light with a peak wavelength of 172 nm. 1 Although the generation rate of D) is expected to be somewhat slower, when irradiated in an atmospheric environment, the adhesive strength decreases significantly if the irradiation time is extended by a few seconds, just as in the case of a wavelength of 172 nm. However, when the wavelength of ultraviolet light exceeds 200 nm, for the reasons mentioned above, the proportion of ultraviolet light that penetrates in the depth direction of the substrate is gradually increased, making the substrate more brittle.

[0051] Step (c) can be any method that allows the catalyst-contributing compound to penetrate into the microporous layer. A typical example is to adjust the surface potential of the substrate as needed, and then immerse the substrate in a chemical solution containing the catalyst-contributing compound. After that, an activation treatment is performed as needed.

[0052] Step (d) can be any method that can form an electroless plating layer on the upper surface of the substrate in which the catalyst contributing compound is bonded to the microporous layer. A typical example is a step in which the substrate is immersed in an electroless metal plating solution after performing step (c).

[0053] In other words, according to the method of the present invention, it is possible to manufacture a resin plating material that exhibits stable adhesion between the substrate and the plating material, while being a method that does not substantially form irregularities on the surface of the substrate.

[0054] In the method for manufacturing the resin plated material, ultrasonic vibration may be applied when performing step (d).

[0055] Conventionally, a method is known in which palladium (Pd) is used as a catalyst to reduce Ni ions with sodium hypophosphite to form an electroless Ni coating (electroless plating layer) on a resin surface. In this method, a substrate including a surface to which Pd particles as a catalyst are attached is immersed in an electroless plating solution, and an electroless plating layer made of Ni2P is formed on the resin surface through the reaction mechanism shown in equations (6) to (8) below. H2er 2- + H2O → HPO3 2- + H + + (1 / 2)H2+ e - …(6) Ni 2+ + 2e - → 2Ni …(7) 2Ni 2+ H2er2 - + 2H + + 5e - → Ni2P + 2H2O …(8)

[0056] However, as a result of diligent research by the inventors, they discovered that minute pores (pinholes) exist at the interface between the electroless plating layer formed by conventional electroless plating methods and the substrate, causing plating defects. The inventors surmise that the cause lies in the following points.

[0057] According to equation (6) above, hydrogen (H2) is inevitably generated during the reaction process. Therefore, during the process of immersing the substrate in the electroless plating solution, bubbles originating from hydrogen gas are generated and adhere to the surface of the substrate. If an electroless plating layer is formed on the surface of the substrate in this state, the bubbles will remain on the surface of the substrate while the electroless plating layer is formed. As a result, pinholes originating from the bubbles are formed in the resulting resin plated material, causing plating defects.

[0058] Furthermore, as a result of the inventor's diligent research, it has been confirmed that even resin-plated materials manufactured through the above steps (a) to (d) may sometimes develop minute pinholes. From this point as well, it can be inferred that the cause of pinhole formation is unrelated to ultraviolet irradiation.

[0059] In contrast, the above method applies ultrasonic vibrations during the formation of the electroless plating layer, which allows hydrogen gas-derived bubbles adhering to the surface of the substrate to be detached from the substrate. This further improves the adhesion between the substrate and the electroless plating layer.

[0060] The processing area may also be defined as the area between the surface and a region where the processing has progressed 3 nm to 50 nm in a depth direction perpendicular to the surface.

[0061] As described above, after step (b), step (c) is performed to bond the catalyst to the microporous layer. Since the outer diameter of the compound containing molecules or atoms that exert a catalytic effect (catalyst-contributing compound) is about 3 nm, if the thickness of the area to be treated is less than 3 nm, the catalyst-contributing compound will not penetrate sufficiently into the voids, and its effect of increasing adhesive strength will be limited. On the other hand, in areas where the treatment has progressed more than 50 nm in depth from the surface, it acts in a direction that weakens the substrate itself, which leads to a decrease in the adhesive strength between the resin and the plating layer.

[0062] The surface modification method may further include a step (e) after step (b) and before step (c) to remove low molecular weight components contained in the substrate.

[0063] As mentioned above, when ultraviolet light is irradiated onto the substrate, the ultraviolet light itself or atomic oxygen O( 1 As a result of D), the polymer constituting the substrate is cleaved. In this process, molecular chains with extremely low molecular weight compared to the resin constituting the substrate may be generated as a by-product. If a catalyst is introduced after step (b), the catalyst is incorporated into these low molecular chains. However, the catalyst incorporated into the low molecular chains does not contribute to improving the adhesive strength.

[0064] As described above, by performing step (e) to remove low molecular weight components contained in the substrate, much of the catalyst introduced thereafter can be incorporated into the voids within the microporous layer. In other words, this method makes it possible to achieve high adhesive strength while reducing the amount of catalyst used.

[0065] Step (e) for removing low molecular weight components includes, for example, alkaline washing, hot water washing, and drying. Of these, alkaline washing is particularly preferred.

[0066] In other words, step (e) may be a step of immersing the substrate after step (b) in an alkaline solution.

[0067] The type of alkaline solution used in this process is not particularly limited, but for example, one or more solutions belonging to the group consisting of sodium hydroxide, lithium hydroxide, and potassium hydroxide can be suitably used.

[0068] The electroless plating apparatus according to the present invention is A pretreatment unit that irradiates a substrate containing an insulating resin material with ultraviolet light of a wavelength of 200 nm or less, A catalyst treatment unit includes a first storage tank in which a solution containing a catalyst is stored, and the substrate, after being irradiated with ultraviolet light by the pretreatment unit, is placed in the first storage tank. A plating treatment unit comprising a second storage tank in which a plating solution is stored, and the substrate after being removed from the catalyst treatment unit is placed in the second storage tank, The pretreatment unit includes a nitrogen gas source, and is characterized in that it irradiates the substrate located within the irradiation area with ultraviolet light while adjusting the oxygen concentration of the atmosphere in the irradiation area to 0.01 volume% to 10 volume% by introducing nitrogen from the nitrogen gas source into the irradiation area to which the ultraviolet light is irradiated.

[0069] According to the electroless plating apparatus described above, it is possible to increase the degree of freedom in controlling the amount of ultraviolet radiation irradiated onto the substrate in the pretreatment unit, and to form a plating layer on the surface of the substrate with high adhesion without forming substantial irregularities on the surface of the substrate.

[0070] The plating unit may include an ultrasonic generator capable of transmitting ultrasonic waves to the plating solution in the second storage tank, and the substrate, after being removed from the catalyst treatment unit, may be positioned in the second storage tank while ultrasonic waves generated from the ultrasonic generator are transmitted to the plating solution.

[0071] The electroless plating apparatus comprises a transport path connecting the pretreatment unit, the catalyst treatment unit, and the plating treatment unit. The substrate may be moved along the transport path while the pretreatment unit, the catalyst treatment unit, and the plating treatment unit each perform their respective processes. [Effects of the Invention]

[0072] According to the present invention, a resin plated material can be manufactured by applying a plating material to the surface of a substrate in a more controllable manner than conventional methods, without creating substantial irregularities on the surface of the substrate. [Brief explanation of the drawing]

[0073] [Figure 1] This graph schematically shows the relationship between the amount of ultraviolet light irradiated onto a substrate and the contact angle on the substrate surface, as previously assumed. [Figure 2] This graph schematically illustrates the conventional relationship between the amount of ultraviolet radiation applied to the substrate and the adhesive strength between the substrate surface and other layers. [Figure 3] This graph schematically shows the relationship between the amount of ultraviolet radiation irradiated onto a substrate in an atmospheric environment and the adhesive strength between the substrate surface and other layers, as derived from the inventors' verification. [Figure 4]This graph shows the relationship between the ultraviolet irradiation time and the contact angle on the substrate surface, and the relationship between the irradiation time and the adhesive strength, when ultraviolet light is irradiated onto the surface of the substrate at a predetermined intensity in an atmospheric environment. [Figure 5] This graph shows the emission spectrum of a Xe excimer lamp superimposed with the absorption spectra of oxygen (O2) and ozone (O3). [Figure 6] This diagram schematically illustrates the progression of ultraviolet light when ultraviolet light from a low-pressure mercury lamp is irradiated onto a substrate. [Figure 7] This diagram schematically shows the molecular chains of the polymer material that constitutes the substrate. [Figure 8] This diagram schematically illustrates how the molecular chains of the polymer material constituting the substrate are significantly cleaved and reduced in molecular size. [Figure 9] This graph schematically shows the relationship between the amount of ultraviolet light irradiated onto the substrate and the adhesive strength between the substrate surface and other layers, when the atmosphere is set to a low oxygen concentration. [Figure 10] This graph shows the relationship between the UV irradiation time and the contact angle on the substrate surface, and the relationship between the irradiation time and the adhesive strength, when the substrate surface is irradiated with UV light at a predetermined intensity under a low-oxygen atmosphere. [Figure 11] This diagram schematically shows the progression of ultraviolet light when ultraviolet light from a Xe excimer lamp is irradiated onto a substrate. [Figure 12] This diagram schematically illustrates how a portion of the molecular chains of the polymer material constituting the substrate are broken, creating voids. [Figure 13] This is a schematic functional block diagram showing the configuration of the electroless plating apparatus according to the present invention. [Figure 14] This is a schematic block diagram showing the configuration of one embodiment of an electroless plating apparatus. [Figure 15] This is a schematic block diagram showing the configuration of another embodiment of an electroless plating apparatus. [Figure 16] This is a schematic cross-sectional view showing an example of the configuration of a pre-processing unit. [Figure 17] This is a schematic cross-sectional view showing another example configuration of the pre-processing unit. [Figure 18] This is a schematic cross-sectional view showing another example configuration of the pre-processing unit. [Figure 19] This graph shows the relationship between UV irradiation time and the peak value of adhesive strength when the surface of a substrate is irradiated with UV light at a predetermined intensity, for different atmospheric oxygen concentrations. [Figure 20] This graph explains the "ratio," which is an indicator used to evaluate the level of controllability. [Figure 21] This is a schematic cross-sectional view showing a state in which an electroless plating layer is formed on the surface of a substrate on which a microporous layer has been formed. [Figure 22] This graph shows the results of TEM-EDS analysis performed on a substrate with an electroless plating layer formed on its upper surface, while the analysis progresses in the depth direction from the interface with the electroless plating layer toward the substrate. [Figure 23] This graph shows the results of mass spectrometry analysis performed using TOF-SIMS on both UV-irradiated and unirradiated substrates to identify substances with lower molecular weights than the constituent materials of the substrates. [Figure 24A] This graph shows the results of MSE testing performed on substrates irradiated with ultraviolet light and those that were not irradiated. [Figure 24B] This graph shows the results from Figure 24A with an approximation line added. [Figure 25] This graph compares the adhesive strength of the substrate surface when alkaline cleaning is performed on the substrate after irradiation with ultraviolet light, and when it is not. [Modes for carrying out the invention]

[0074] In the following, embodiments of the method for manufacturing a resin plated material and the electroless plating apparatus according to the present invention will be described with reference to the drawings as appropriate. However, the following 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 may not correspond to each other even between drawings.

[0075] Furthermore, in the following drawings, elements identical to those in Figure 11 are given the same reference numerals, and their explanations are simplified.

[0076] The present invention relates to a method for manufacturing a resin-plated material, comprising the steps of (a) preparing a substrate 3 containing an insulating resin material, and (b) irradiating the surface of the substrate 3 with ultraviolet light L10 with a wavelength of 200 nm or less in an atmosphere 1 with an oxygen concentration of 0.01 volume% to 10 volume%. Step (b) is a step of modifying the treatment target area (an area within a distance d10 in the depth direction), including the surface 3a of the substrate 3, into a microporous layer 4a (see Figure 21) containing voids 4 (see Figure 12) of the order of nanometers.

[0077] Furthermore, the method for manufacturing a resin plated material according to the present invention includes, after step (b), a step (c) of bonding a catalyst to the microporous layer 4a, and a step (d) of forming an electroless plating layer on the upper surface of the substrate via the catalyst.

[0078] The base material 3 is not limited to any type of insulating resin material, and examples include polyimide resin, liquid crystal polymer, polystyrene, polyphenylene sulfide, polyether ether ketone, polyethylene naphthalate, cycloolefin polymer, cyclic olefin copolymer, polytetrafluoroethylene, or epoxy resin. The base material 3 may be a sheet-like film or a plate-like member.

[0079] Figure 13 is a schematic block diagram showing an example of the configuration of an electroless plating apparatus suitable for use with the resin plating material manufacturing method according to the present invention. The electroless plating apparatus 70 includes a pretreatment unit 71, a catalyst treatment unit 73, and a plating treatment unit 75.

[0080] The pretreatment unit 71 is a unit that irradiates a substrate 3 containing an insulating resin material with a predetermined amount of ultraviolet light. By passing through the pretreatment unit 71, a microporous layer 4a (see Figure 21), which will be described later, is formed near the surface of the substrate 3.

[0081] The catalyst treatment unit 73 is a unit that applies a catalyst to a substrate 3 in which a microporous layer 4a is formed near the surface. The catalyst is bonded to the microporous layer 4a by passing through the catalyst unit 73.

[0082] The plating unit 75 is a unit that applies plating material to the substrate 3 to which the catalyst is bonded. By passing through the plating unit 75, an electroless plating layer is formed on the surface of the substrate 3, and a resin plating material is obtained.

[0083] Figure 14 is a schematic block diagram showing the configuration of one embodiment of an electroless plating apparatus 70. The electroless plating apparatus 70 shown in Figure 14 forms an electroless plating layer on the surface of the substrate 3 while transporting the substrate 3 to be processed along the transport path 40 under the drive of the transport roller 41. The configuration in Figure 14 is assumed to be, for example, a case where the substrate 3 is in the shape of a film. In Figure 14, a part of the substrate 3 is exaggerated in the illustration for ease of understanding.

[0084] The pretreatment unit 71 includes a light source device 5 and irradiates the surface of the substrate 3, which is transported along the transport path 40, with ultraviolet light L10. After passing through the pretreatment unit 71, the substrate 3 is sent to the catalyst treatment unit 73. The catalyst treatment unit 73 includes a first storage tank 61 in which a solution containing a catalyst (catalyst-granulating liquid) 61a is stored. The substrate 3 sent to the catalyst treatment unit 73 is immersed in the catalyst-granulating liquid 61a stored in the first storage tank 61.

[0085] After passing through the catalyst treatment unit 73, the substrate 3 is sent to the plating treatment unit 75. The plating treatment unit 75 includes a second storage tank 62 in which the plating solution 62a is stored. The substrate 3 sent to the plating treatment unit 75 is immersed in the plating solution 62a stored in the second storage tank 62.

[0086] In this embodiment, the plating unit 75 is equipped with an ultrasonic generator 81 capable of generating ultrasonic waves 81a. While the substrate 3 is immersed in the plating solution 62a, ultrasonic waves 81a emitted from the ultrasonic generator 81 are transmitted to the substrate 3 via the plating solution 62a.

[0087] Although not shown in Figure 14, the electroless plating apparatus 70 may also include units other than the catalyst treatment unit 73 and the plating treatment unit 75. For example, a unit for adjusting the surface potential of the substrate 3, a unit for rinsing the substrate 3 with water after treatment, a unit for activating the substrate 3, etc., may be provided as needed.

[0088] Figure 14 illustrates a configuration in which the pretreatment unit 71, catalyst treatment unit 73, and plating unit 75 process the substrate 3 in a single line. However, one or more of these processing units may process the substrate 3 in a batch manner. Figure 15 is a schematic diagram showing a configuration in which the catalyst treatment unit 73 and the plating unit 75 process the substrate 3 in a batch manner. When the substrate 3 is a plate-like body, the batch processing method shown in Figure 15 is suitably utilized.

[0089] As shown in Figure 15, a holder 66 connected to a support member 65 may be provided, and the base material 3 fixed by this holder 66 may be immersed in the catalyst-applying liquid 61a in the first storage tank 61 provided in the catalyst treatment unit 73 by the movement of the holder 66. In this case, after a predetermined time has elapsed, the base material 3 is removed from the first storage tank 61 by the movement of the holder 66 and transferred to a subsequent treatment unit (in this case, a plating treatment unit 75).

[0090] Similarly, in the plating unit 75, the substrate 3 is immersed in the plating solution 62a in the second storage tank 62 for a predetermined time by the movement of the holder 66, and then the substrate 3 is removed from the second storage tank 62. While the substrate 3 is immersed in the plating solution 62a, ultrasonic waves 81a emitted from the ultrasonic generator 81 are transmitted to the substrate 3 via the plating solution 62a.

[0091] Figure 16 is a schematic diagram showing one example configuration of the pre-treatment unit 71. The pre-treatment unit 71 shown in Figure 16 performs surface treatment on the substrate 3 while transporting it along the transport path 40.

[0092] The pre-processing unit 71 includes a light source device 5, which includes a Xe excimer lamp 10. The light source device 5 is equipped with an irradiation window 6, and ultraviolet light L10 from the Xe excimer lamp 10 is irradiated to the transport path 40 side through the irradiation window 6. The irradiation window 6 can be made of any material that transmits ultraviolet light L10, for example, synthetic quartz glass. The light source device 5 may also be configured such that nitrogen gas is sealed in the space in which the Xe excimer lamp 10 is installed. In the example shown in Figure 16, nitrogen gas is introduced from a nitrogen gas source 34 into the space in which the Xe excimer lamp 10 is installed. In this example, an exhaust port 35 is provided, and it is assumed that nitrogen gas is continuously flowing from the nitrogen gas source 34 during processing. However, this configuration is merely an example.

[0093] The substrate 3, placed on the transport path 40, moves along the transport path 40 in the dX direction, is taken in through the entrance 18, and approaches the point where it faces the irradiation window 6. Thereafter, the substrate 3 continues to move in the dX direction, is irradiated with ultraviolet light L10 through the irradiation window 6, and is removed to the outside through the exit 19. After that, the substrate 3 is sent to the subsequent processing unit (catalyst processing unit 73, etc.) described above.

[0094] If the base material 3 is a plate-like body, the transport path 40 can be structured to include, for example, multiple transport rollers. If the base material 3 is a sheet-like film, the transport path 40 can be structured to have, for example, a sheet-like film stretched between an unwinding roll and a winding roll, and wound from the unwinding roll to the winding roll.

[0095] The light source device 5 is positioned such that the irradiation window 6 is close to the substrate 3 on the transport path 40 with respect to the optical axis of the ultraviolet light L10. Specifically, the distance between the irradiation window 6 and the substrate 3 is preferably 1 mm to 50 mm, and more preferably 2 mm to 10 mm.

[0096] In this explanation, we assume that the ultraviolet light source provided by the light source device 5 is a Xe excimer lamp 10. However, as mentioned above, any light source that emits ultraviolet light with a peak wavelength of 200 nm or less is acceptable, and is not limited to a Xe excimer lamp 10. For example, solid-state light sources such as LEDs or laser diodes may also be used.

[0097] The pretreatment unit 71 comprises a nitrogen gas source 31, an oxygen-containing gas source 32, and a gas mixer 33. The nitrogen gas source 31 is a gas source containing nitrogen gas. The oxygen-containing gas source 32 is a gas source containing oxygen-containing gas, and a typical example is CDA (clean dry air). The gas mixer 33 mixes the nitrogen gas from the nitrogen gas source 31 and the oxygen-containing gas from the oxygen-containing gas source 32 while adjusting the flow rate ratio to generate and deliver a gas for the treatment space. This gas for the treatment space delivered from the gas mixer 33 constitutes the atmosphere 1 of the substrate 3. Figure 16 illustrates a case where the direction of flow of this gas for the treatment space is the same as the direction of flow of the substrate 3 (dX direction), but it may be reversed. In other words, the processing space gas, which is a mixed gas of nitrogen gas from the nitrogen gas source 31 and oxygen-containing gas from the oxygen-containing gas source 32, may be introduced against the flow of the substrate 3, or in other words, from the downstream side to the upstream side in the conveying direction of the conveying path 40.

[0098] As mentioned above, if the pre-treatment unit 71 is equipped with a nitrogen gas source 34, the nitrogen gas source 34 may be shared with the nitrogen gas source 31.

[0099] Furthermore, an oxygen concentration detector (not shown) is installed in the space through which the substrate 3 passes, and the gas mixer 33 may be feedback controlled so that the oxygen concentration of the atmosphere 1 in the space becomes a predetermined constant value. The same applies to the pretreatment unit 71 shown in Figure 17, which will be described later.

[0100] The gas mixer 33 is adjusted to a mixing ratio such that the atmosphere 1 of the substrate 3 has a low oxygen concentration. Specifically, the oxygen concentration of atmosphere 1 is 0.01% to 10% by volume, more preferably 0.01% to 5% by volume, and particularly preferably 0.1% to 5% by volume.

[0101] The pre-treatment unit 71 preferably includes sub-chambers 21 and 22. The sub-chambers 21 and 22 forcibly exhaust gases leaking from the processing space through the inlet 18 or outlet 19 to the outside.

[0102] According to the pretreatment unit 71, as the substrate 3 moves along the transport path 40, it is irradiated with ultraviolet light L10, and the area near the surface of the substrate 3 is modified into a microporous layer 4a (see Figure 21) containing voids 4 (see Figure 12).

[0103] In the configuration of the pre-treatment unit 71 shown in Figure 16, the space containing the Xe excimer lamp 10 (light source device 5) and the space through which the substrate 3 passes were separated. However, as shown in Figure 17, both may be arranged in the same space (processing space 8). Figure 17 is a schematic diagram illustrating another example of a system for implementing the surface modification method according to the present invention, following Figure 16.

[0104] In the pretreatment unit 71 shown in Figure 17, the gas for the treatment space, which is sent from the gas mixer 33, is supplied into the treatment space 8 via the gas supply pipe 16. In the case of the pretreatment unit 71 shown in Figure 17, it is preferable to provide a gas outlet 17 for forcibly exhausting the gas in the treatment space 8 to the outside. At the start of the treatment, the gas in the treatment space 8 is first discharged via the gas outlet 17, and then a low-oxygen-concentration mixed gas sent from the gas mixer 33 is supplied into the treatment space 8 via the gas supply pipe 16, thereby making the atmosphere 1 of the substrate 3 a low-oxygen concentration.

[0105] In this case, as shown in Figure 17, it is preferable to provide the sub-chambers 21 and 22 at two locations, above and below the transport path 40.

[0106] The surface treatment of the substrate 3 does not necessarily need to be performed while it is being transported. That is, even in the case of the pretreatment unit 71 shown in Figures 16 and 17, the substrate 3 may be transported to a location where ultraviolet light L10 from the Xe excimer lamp 10 is irradiated, and then the transport path 40 may be stopped while the ultraviolet light L10 is irradiated.

[0107] Alternatively, as shown in Figure 18, the substrate 3 may be irradiated with ultraviolet light L10 within a closed chamber 7. In the pretreatment unit 71 shown in Figure 18, similar to the pretreatment unit 71 shown in Figure 16, the space 7a where the Xe excimer lamp 10 is housed and the space 7b on which the substrate 3 is placed are separated. A low-oxygen concentration treatment space gas, delivered from the gas mixer 33, is supplied to the space 7b on which the substrate 3 is placed. In addition, nitrogen gas is introduced into the space 7a where the Xe excimer lamp 10 is housed from the nitrogen gas source 34, similar to the configuration illustrated in Figure 16. In this case as well, it is preferable to provide a gas outlet 17 for forcibly exhausting the gas in space 7b. The nitrogen gas source 34 may be shared with the nitrogen gas source 31.

[0108] After irradiation with ultraviolet light L10 by the pretreatment unit 71 illustrated in Figures 16 to 18, the substrate 3 is modified in the vicinity of the surface 3a by cleaving the polymer chains constituting the substrate 3, resulting in a microporous layer 4a (see Figure 21) containing voids 4 (see Figure 12). At this time, in some areas near the surface 3a, molecular chains with extremely low molecular weight compared to the resin constituting the substrate 3 may be generated as a by-product. Therefore, the substrate 3 after irradiation with ultraviolet light L10 may be removed and subjected to alkaline washing, hot water washing, or drying to remove these low molecular weight components. Among these, alkaline washing is particularly preferred.

[0109] As an alkaline cleaning treatment, a method can be employed in which the substrate 3, after irradiation with ultraviolet light L10, is immersed in an alkaline solution such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. The alkali concentration of this alkaline solution is preferably 4% to 20%, and more preferably 8% to 12%. The temperature of the alkaline solution is preferably 40°C to 80°C, and particularly preferably 60°C to 70°C. If the temperature of the alkaline solution is below 40°C, the cleaning ability will not be fully realized, and if it exceeds 80°C, the alkaline components will easily vaporize. The immersion time of the substrate 3 in the alkaline solution is not particularly limited, but typically, a immersion time of 10 seconds or more is expected to be effective in removing low molecular weight materials.

[0110] In other words, when performing alkaline cleaning treatment, an alkaline cleaning unit (not shown) may be provided between the pre-treatment unit 71 and the catalyst treatment unit 73. This alkaline cleaning unit, like the catalyst treatment unit 73, should be equipped with a storage tank containing a predetermined chemical solution (in this case, the alkaline solution described above) and should be configured to allow the substrate 3, after passing through the pre-treatment unit 71, to be immersed in the alkaline solution. [Examples]

[0111] The following are specific test examples to further explain the present invention, but the present invention is not limited to the embodiments of these test examples.

[0112] (Verification 1: Oxygen concentration in the atmosphere) Referring to Figure 10, the relationship between the irradiation time of ultraviolet light L10 and the adhesive strength of substrate 3 was measured using the same method as described above. That is, the verification method is as follows.

[0113] As a sample of substrate 3, polyimide resin (Toray DuPont: Kapton 100EN-C) was prepared. Using a light irradiation device (Ushio Inc.: SVC 232 Series, peak wavelength 172 nm), ultraviolet light L10 was irradiated onto the surface of the sample from a distance (separation distance) of 3 mm, under seven different oxygen concentration conditions: 0.01 vol%, 0.1 vol%, 0.5 vol%, 1 vol%, 5 vol%, 10 vol%, and 21 vol%. The atmosphere with an oxygen concentration of 21 vol% corresponds to air 100 shown in Figure 6. The light irradiation device is equipped with a Xe excimer lamp 10.

[0114] After irradiating each sample with UV L10 for varying irradiation times, the irradiated surfaces of the same samples were bonded together using an adhesive sheet (Aron Mighty AF-700, manufactured by Toagosei Co., Ltd.) and laminated at 100°C. Subsequently, a compression treatment was performed at 180°C for 30 minutes while applying pressure of 2 MPa to 3 MPa. The peak value of the adhesive strength of the bonded samples obtained after compression was measured according to the method conforming to JIS K 6854-3.

[0115] Figure 19 is a graph in which the relative value of the peak adhesive strength is plotted on the vertical axis and the irradiation time of ultraviolet L10 is plotted on the horizontal axis.

[0116] As shown in Figure 19, the rate of decrease in adhesive strength due to longer irradiation time is mitigated when UV L10 is irradiated in a low-oxygen atmosphere compared to when UV L10 is irradiated in an atmospheric atmosphere. Specifically, in the case of an atmospheric atmosphere, the adhesive strength reached its maximum value at an irradiation time of approximately 6 seconds, and the adhesive strength decreased to less than 50% of the peak value when the irradiation time was extended by another 6 seconds.

[0117] In contrast, in an atmosphere with an oxygen concentration of 10% by volume or less, even if ultraviolet L10 irradiation is continued for an additional 20 seconds after the irradiation time at which the adhesive strength reaches its peak value, the adhesive strength remains at 50% or more of the peak value. In particular, as shown in the results in Figure 19, it can be seen that the lower the oxygen concentration, the more the decrease in adhesive strength associated with longer irradiation times is suppressed.

[0118] The results in Figure 19 show that by reducing the oxygen concentration of the atmosphere from atmospheric (21%), the allowable irradiation time for ultraviolet light L10 to achieve an adhesive strength close to the peak value can be extended. In other words, the higher the ratio of the allowable irradiation time to the irradiation time required to achieve the peak adhesive strength, the greater the flexibility in the irradiation time of ultraviolet light L10 to impart high adhesive strength to the substrate 3. That is, the higher the ratio, the better the controllability when performing the modification treatment on the substrate 3. Therefore, the level of controllability can be evaluated based on the value of this ratio.

[0119] Figure 20 is a graph illustrating the "ratio" used as an indicator to evaluate the degree of controllability. Generally, the acceptable degree of variation when discussing adhesive strength is considered to be 5%. Therefore, the degree of controllability can be evaluated by the ratio (τ95 / tp) of the allowable irradiation time τ95 (the time required to irradiate the substrate 3 to achieve an adhesive strength close to the peak value (i.e., 95% or more of the peak value) to the irradiation time tp required to achieve the peak adhesive strength of the substrate 3. Alternatively, if the irradiation time tp required to achieve the peak adhesive strength of the substrate 3 is 10 seconds or more, a deviation of 10 seconds or more in irradiation time is acceptable, indicating high controllability.

[0120] Table 1 below shows the results of evaluating the level of controllability of the surface treatment on substrate 3 based on the ratio (τ95 / tp) calculated according to the oxygen concentration of the atmosphere using the method described above, based on the results in Figure 19. In Table 1, a ratio (τ95 / tp) of 0.3 or higher indicates high controllability and is rated as "Evaluation A," while low controllability is rated as "Evaluation C."

[0121] [Table 1]

[0122] According to Table 1, by lowering the oxygen concentration of the atmosphere compared to that of the atmosphere, the ratio (τ95 / tp) can be made 0.5 or higher, or the allowable time τ95 can be made 10 seconds or higher. As a result, it becomes possible to modify only the vicinity of the surface 3a of the substrate 3 without precisely controlling the irradiation time.

[0123] (Verification 2: Confirmation of the microporous layer) After irradiation with ultraviolet light L10, a catalyst is applied to the substrate 3, and then an electroless plating layer is formed, thereby creating a conductive layer on the insulating surface of the substrate 3. Figure 21 is a schematic cross-sectional view showing the state in which the electroless plating layer 50 is formed on the surface of the substrate 3 (i.e., "resin plating material 51").

[0124] By irradiating the surface of the substrate 3 with ultraviolet light L10 using the method described above, the area near the surface 3a of the substrate 3 is modified, and a microporous layer 4a containing voids 4 (see Figure 12) is formed. When a catalyst is applied in this state, it is thought that the catalyst-contributing compound is incorporated into the voids 4 within the microporous layer 4a.

[0125] Therefore, as shown in Figure 21, if a substance originating from the catalyst can be detected inside the substrate 3 when analyzing the cross-section of the substrate 3 while moving in the depth direction dZ toward the substrate 3 side from the surface 3a (the interface between the substrate 3 and the electroless plating layer 50), it proves that a void 4 existed near the surface 3a of the substrate 3, or in other words, that a microporous layer 4a was formed.

[0126] Under an atmosphere of 0.1% oxygen concentration (atmosphere 1), the substrate 3 was irradiated with ultraviolet light L10 in the same manner as in Verification 1, and then an electroless plating layer 50 was formed using the following method. However, in this verification, an epoxy resin was used as the substrate 3.

[0127] After irradiation with ultraviolet light L10, the substrate 3 was immediately immersed in conditioner solution M1 to degrease it and adjust its surface potential to a cationic state. Next, after rinsing with water, the substrate 3 was immersed in pre-dip solution M2 to adjust its surface potential to anionic state. Next, the substrate 3 was immersed in catalyst-granting solution M3 to impart a catalyst complex to its surface. Next, after rinsing with water, the substrate 3 was immersed in activation solution M4 to reduce the catalyst complex to metal. Next, after rinsing with water, the substrate 3 was immersed in electroless metal plating solution M5 to reduce metal ions via the catalyst and form an electroless metal film on the surface of the substrate 3. The step of immersing the substrate 3 in catalyst-granting solution M3 corresponds to step (c), and the step of immersing the substrate 3 in electroless metal plating solution M5 corresponds to step (d). The step of preparing the substrate 3 corresponds to step (a), and the step of irradiating the substrate 3 with ultraviolet light L1 corresponds to step (b). In other words, the resin plating material 51 is manufactured from the base material 3 through processes (a) to (d).

[0128] When immersing the base material 3 in each chemical solution, the base material 3 was dipped in the chemical solution pod containing the respective chemical solution for a predetermined time (several seconds to several minutes) before being removed. For the water rinsing process, the base material 3 was dipped in the washing pod containing washing water (pure water) for a predetermined time (several seconds to several minutes) before being removed.

[0129] The chemical solutions used were as follows: • Conditioner liquid M1: OPC-370 Condiclean ELA (manufactured by Okuno Pharmaceutical Co., Ltd.) • Predip solution M2: A mixture of OPC Predip 49L (manufactured by Okuno Pharmaceutical Co., Ltd.) and 98% sulfuric acid. • Catalyst-inducing solution M3: A mixture of OPC-50 inducer AM and OPC-50 inducer CM (both manufactured by Okuno Pharmaceutical Co., Ltd.) • Activation treatment solution M4: A mixture of OPC-150 Cristar RW (manufactured by Okuno Pharmaceutical Co., Ltd.) and boric acid. • Electroless metal plating solution M5: A mixture of ATS Adcopper IW-A, ATS Adcopper IW-M, ATS Adcopper IW-C, and electroless copper RN (all manufactured by Okuno Pharmaceutical Co., Ltd.)

[0130] Figure 22 is a graph showing the results of TEM-EDS (JEM-2100PLUS, manufactured by JEOL Ltd.) analysis of the interface between the substrate 3 and the electroless plating layer 50. In Figure 22, the horizontal axis represents the propagation distance (nm) from the interface between the substrate 3 and the electroless plating layer 50 to the depth dZ. In Figure 22, the vertical axis represents the value obtained by dividing the number of detected palladium (Pd), a substance constituting the catalyst, by the effective time (cps / ROI). A larger value indicates a higher amount of Pd.

[0131] Figure 22 shows that catalyst-derived Pd is present in a region 30 nm deep in the dZ direction toward the substrate 3 from the interface between the substrate 3 and the electroless plating layer 50. From the results in Figure 22, it is estimated that the thickness of the microporous layer 4a formed by the voids 4 in the substrate 3 is in the range of 30 nm to 40 nm.

[0132] Incidentally, when the substrate 3 is irradiated with ultraviolet light L10, as described above, some of the polymer chains constituting the substrate 3 are cleaved, and a low molecular weight substance is secondarily generated. Therefore, it is expected that by mass spectrometry of the substrate 3 after irradiation with ultraviolet light L10 using TOF-SIMS, a substance different from the polymer material constituting the substrate 3 will be detected. Furthermore, if the ultraviolet light L10 only reaches the vicinity of the surface 3a of the substrate 3, it is expected that the low molecular weight substance will be detected only in this region.

[0133] As substrate 3, a liquid crystal polymer resin defined by the following formula (9) was prepared, and substrate 3 was irradiated with ultraviolet light L10 under an atmosphere 1 with an oxygen concentration of 0.1 volume% in the same manner as above. Next, mass spectrometry was performed by TOF-SIMS while sputtering was carried out on the surface of substrate 3 using an Ar gas cluster ion beam (Ar-GCIB). Both sputtering and mass spectrometry were performed using TOF.SIMS5 manufactured by ION-TOF. For comparison, mass spectrometry was performed on substrate 3 made of the same material using the same method without irradiation with ultraviolet light L10.

[0134] For mass spectrometry, the spectral intensity of C6H5O, which is presumed to be obtained by the cleavage of some molecular chains in the liquid crystal polymer resin defined by equation (9), was used for normalization. The results are shown in Figure 23.

[0135] [ka]

[0136] For substrate 3 that is not irradiated with ultraviolet light L10, no signal originating from C6H5O is generated in principle. On the other hand, as shown in the results in Figure 23, it is confirmed that the intensity of the signal originating from C6H5O generated from substrate 3 irradiated with ultraviolet light L10 decreases as it progresses in the depth direction. Furthermore, when the intensity of the signal originating from C6H5O generated from substrate 3 irradiated with ultraviolet light L10 reaches a depth where it is about the same as the intensity of the signal originating from C6H5O from substrate 3 that is not irradiated with ultraviolet light L10, it is suggested that ultraviolet light L10 is no longer substantially irradiated to regions deeper than this point.

[0137] In other words, the results in Figure 23 suggest that the substrate 3 was modified into a microporous layer 4a over a region extending approximately 50 nm in depth from the surface 3a.

[0138] As described above, when the substrate 3 is irradiated with ultraviolet light L10, some of the polymer chains constituting the substrate 3 are cleaved. Therefore, it is thought that the strength near the surface of the substrate 3 decreases compared to before irradiation with ultraviolet light L10. For this reason, the strength in the depth direction of the substrate 3 was evaluated by MSE (Micro Slurry-jet Erosion) testing.

[0139] The MSE test is an impact abrasion test using solid microparticles. A fixed amount of microparticles is projected onto the same spot on the surface of a test specimen to induce erosion abrasion due to impact, and the depth of the abrasion is measured. When depth measurement and shape measurement are repeated and a graph is created, if layers of different hardness exist on the substrate surface, the rate of abrasion progression will change, resulting in graphs with different slopes.

[0140] As base material 3, polyimide resin (Toray DuPont: Kapton 100EN-C) was prepared, the same as that used in Verification 1. This base material 3 was irradiated with ultraviolet light L10 under an atmosphere 1 with an oxygen concentration of 0.1 volume%, using the same method as described above. Next, a slurry jet containing alumina particles was locally sprayed onto the surface of base material 3 using a spraying device, and the maximum wear depth of the localized area formed by the spray was measured with a shape measuring instrument. The erosion rate (= maximum wear depth μm / amount of projected particles g) was then calculated from the ratio of the degree of wear (depth) to the amount of projected particles at the sprayed localized area. The amount of projected particles was a value calculated based on the slurry flow rate, using a pre-defined relationship for alumina slurry containing alumina particles.

[0141] The equipment used for the verification was as follows: • Injection device: Slurry local injection abrasion device (Parmeso, MSE-A), nozzle diameter 1mm x 1mm, projection distance 4mm • Shape measuring instrument: Stylus-type shape measuring instrument (manufactured by Kosaka Research Institute, PU-EU1), stylus tip radius R=2μm, load 80μN, magnification 20,000, length measurement 1mm, measurement speed 0.1mm / sec

[0142] Figure 24A is a graph in which the vertical axis represents depth (erosion depth) and the horizontal axis represents the erosion rate. For the verification, three types of substrate 3 were used: (b) when the irradiation time of ultraviolet L10 was 25 seconds, (c) when the irradiation time was 120 seconds, and (a) when ultraviolet L10 was not irradiated for comparison.

[0143] From the above definition, a high erosion rate means that the depth of wear is greater for the same amount of projected particles, and therefore the mechanical strength of the substrate 3 in the depth direction region to which the slurry jet was sprayed during that time is weak. Conversely, a low erosion rate means that the depth of wear is shallower for the same amount of projected particles, and therefore the mechanical strength of the substrate 3 in the depth direction region to which the slurry jet was sprayed during that time is strong. For ease of understanding, the "strength" of mechanical strength is schematically indicated in Figure 24A.

[0144] According to Figure 24A, the graph (b,c) corresponding to substrate 3 irradiated with ultraviolet light L10 shows a slope near the surface, and after progressing to a certain depth, it shows almost the same slope as the graph (a) corresponding to substrate 3 not irradiated with ultraviolet light L10. This result means that the intensity near the surface of substrate 3 tends to decrease compared to deeper areas after irradiation with ultraviolet light L10. In other words, it is suggested that a microporous layer 4a is formed near the surface 3a of substrate 3 after irradiation with ultraviolet light L10.

[0145] Furthermore, even when not irradiated with UV L10, a slight decrease in strength is observed in areas very close to surface 3a, which is thought to be due to the resin manufacturing process.

[0146] Figure 24B shows the graph in Figure 24A with approximation lines superimposed. Approximation line k1 is the approximation line for the test results corresponding to the original strength of substrate 3 (polyimide resin) that was not irradiated with ultraviolet light L10. Approximation lines k2 and k3 correspond to the approximation lines in the graph of the results for substrate 3 that was irradiated with ultraviolet light L10, where the slope is significantly inverted compared to approximation line k1.

[0147] By comparing approximation line k1 with approximation lines k2 and k3, it can be understood that the depth regions indicated by approximation lines k2 and k3 represent the regions where the intensity of the substrate 3 decreased due to irradiation with ultraviolet light L10, i.e., the regions where the microporous layer 4a is formed. Therefore, it can be concluded that in the substrate 3 irradiated with ultraviolet light L10 for 25 seconds, the microporous layer 4a is formed up to the depth region at the intersection of approximation line k1 and approximation line k2. Similarly, in the substrate 3 irradiated with ultraviolet light L10 for 120 seconds, it can be concluded that the microporous layer 4a is formed up to the depth region at the intersection of approximation line k1 and approximation line k3.

[0148] According to the results in Figure 24B, when polyimide resin is used as the substrate 3 and irradiated with ultraviolet light L10 for 25 seconds, it can be estimated that the substrate 3 is modified into a microporous layer 4a over a region of approximately 30 nm in depth from the surface 3a. Similarly, when polyimide resin is used as the substrate 3 and irradiated with ultraviolet light L10 for 120 seconds, it can be estimated that the substrate 3 is modified into a microporous layer 4a over a region of approximately 50 nm in depth from the surface 3a.

[0149] (Verification 3: Cleaning with alkaline solution) The effect of treating substrate 3 with UV L10 followed by alkaline cleaning was verified. The same material as in Verification 1 was used as the sample for substrate 3.

[0150] The surface of the sample was irradiated with ultraviolet light L10 from a distance of 3 mm using an ultraviolet irradiation device (Ushio Inc.: SVC 232 Series, peak wavelength 172 nm) in an atmosphere with an oxygen concentration of 0.2 volume%. Subsequently, the peak value of the adhesive strength was measured in the same manner as in Verification 1 without alkaline cleaning treatment, and this was designated as Example 8. The peak value of the adhesive strength was measured in the same manner as in Verification 1 after alkaline cleaning treatment, and this was designated as Example 9, and the adhesive strengths were compared. The results are shown in Figure 25. For comparison, the peak value of the adhesive strength of the sample that was not irradiated with ultraviolet light L10 is shown as Comparative Example 2 in Figure 25.

[0151] In Example 9, the alkaline cleaning treatment was performed using the following method.

[0152] The sample (substrate 3) after irradiation with ultraviolet light L10 was immersed for 2 minutes in a 2.5 mol / L (10% by mass) NaOH aqueous solution heated to 65°C. After removing the sample, it was washed by immersion in pure water for 1 minute. This alkaline washing process corresponds to step (e).

[0153] As shown in Figure 25, it can be seen that the adhesive strength of substrate 3 is further increased by performing alkaline cleaning after treating it with ultraviolet light L10. In the case of the sample in Example 8, where alkaline cleaning was not performed, the molecules of the adhesive contained in the adhesive sheet bind to the low molecular weight chains that are incidentally generated by irradiation with ultraviolet light L10. These adhesive molecules do not contribute to adhesion during bonding. In other words, it is presumed that the adhesive strength was lower than in Example 9 because some of the introduced adhesive did not contribute to the adhesion between substrate 3 and other layers.

[0154] In Example 9, after treating the substrate 3 with ultraviolet light L10, alkaline cleaning is performed to remove low molecular weight chains from the surface of the substrate 3, and then bonding is carried out via an adhesive sheet. As a result, most of the introduced adhesive can be incorporated into the voids 4 (see Figure 12) within the microporous layer 4a (see Figure 21) created by the ultraviolet light L10 treatment. This is thought to have resulted in an even greater increase in adhesive strength compared to Example 8.

[0155] From this perspective, it is believed that removing low-molecular-weight materials by methods other than alkaline cleaning after treatment with ultraviolet light can similarly enhance adhesive strength.

[0156] In this Verification 3, adhesive strength was verified using an adhesive. However, from the perspective of bonding the material necessary for adhesion into the voids 4 within the microporous layer 4a, the same discussion as in the case of catalyst-based adhesion is possible. In other words, even when forming an electroless plating layer, it is presumed that performing an alkaline cleaning treatment beforehand will further enhance the adhesive strength.

[0157] (Verification 4: Plating process with ultrasonic vibration) The effect of applying ultrasonic waves 81a during the plating process in the plating unit 75 was verified.

[0158] Example 10: Under an atmosphere 1 with an oxygen concentration of 0.1%, the substrate 3 was irradiated with ultraviolet light L10, and then an electroless plating layer 50 was formed in accordance with the method of Verification 2. However, the same polyimide resin (Toray DuPont: Kapton 100EN-C) as in Verification 1 was used as the substrate 3. Therefore, the chemicals used during the plating process differed from those in Verification 2 and were as follows. • Conditioner liquid M1: Top SAPINA Pre-conditioner (manufactured by Okuno Pharmaceutical Co., Ltd.) • Predip Solution M2: A mixture of Top SAPINA Predip (manufactured by Okuno Pharmaceutical Co., Ltd.) and 98% sulfuric acid. • Catalyst-granting solution M3: A mixture of Top SAPINA Catalyst A and Top SAPINA Catalyst C (both manufactured by Okuno Pharmaceutical Co., Ltd.) • Activation treatment solution M4: A mixture of Top SAPINA accelerator (manufactured by Okuno Pharmaceutical Co., Ltd.) and boric acid. • Electroless metal plating solution M5: A mixture of TopSAPINA Copper A, TopSAPINA Copper B, TopSAPINA Copper C, TopSAPINA Copper D (all manufactured by Okuno Pharmaceutical Co., Ltd.) and 25% ammonia water.

[0159] However, in this verification 4, when immersing the substrate 3 in the electroless metal plating solution M5, the ultrasonic generator 81 was driven to transmit ultrasonic waves 81a to the electroless metal plating solution M5. The ultrasonic generator 81 used was an MCS-2 manufactured by AS ONE Corporation, and ultrasonic waves 81a were input at a frequency of 40 kHz for 5 minutes.

[0160] Example 11: Plating treatment was performed on the substrate 3 in the same manner as in Example 10, except that the ultrasonic generator 81 was not driven. Comparative Example 3: Plating treatment was performed on the substrate 3 in the same manner as in Example 10, except that irradiation with ultraviolet light L10 as a pretreatment was not performed. Comparative Example 4: Plating treatment was performed on the substrate 3 in the same manner as in Comparative Example 3, except that the ultrasonic generator 81 was not driven.

[0161] The surfaces of the resin-plated materials obtained using the substrates of Example 10, Example 11, Comparative Example 3, and Comparative Example 4 were observed under a microscope while illuminated. The results are shown in Table 2.

[0162] [Table 2]

[0163] Multiple pinholes were observed on the plated surface of the resin plated material in Comparative Example 3. Furthermore, the plating on the resin plated material in Comparative Example 4 was peeling off the surface, indicating a plating defect.

[0164] No pinholes were observed in the resin plating material of Example 10. Pinholes were observed in the resin plating material of Example 11, similar to Comparative Example 3. However, as described below, the resin plating material of Example 11 had stronger plating adhesion than Comparative Example 3, and therefore exhibited superior performance as a resin plating material compared to Comparative Example 3.

[0165] For both the resin-plated materials of Example 11 and Comparative Example 3, an electrolytic copper plating layer was formed using a known method, and then the peel strength was measured according to test method A specified in JIS C 6471:1995 (Test method for copper-clad laminates for flexible printed wiring boards). As a result, the peel strength of the resin-plated material of Example 11 was 9.5 N / cm, while that of the resin-plated material of Comparative Example 3 was 8.0 N / cm.

[0166] When ultrasonic waves 81a are transmitted to the electroless metal plating solution M5 using the ultrasonic generator 81, the frequency of the ultrasonic waves 81a is preferably 10kHz to 200kHz, and more preferably 20kHz to 100kHz. If ultrasonic waves 81a with a frequency exceeding 200kHz are transmitted to the electroless metal plating solution M5, catalyst particles and their aggregates adsorbed on the resin plating material may be removed, and the electroless plating layer 50 (see Figure 21) may not be formed. On the other hand, if the frequency of the ultrasonic waves 81a is low, below 10kHz, the vibration energy may not be sufficient, and it may not be possible to remove bubbles adhering to the surface of the substrate 3.

[0167] In the above embodiment, the case in which ultrasonic waves 81a are applied during the step (d) of forming the electroless plating layer was described, but the case in which ultrasonic waves 81a are not applied is also within the scope of the present invention. [Explanation of Symbols]

[0168] 1: Atmosphere 3: Base material 3a: Surface of the substrate 4 :Void 4a: Microporous layer 5:Light source device 6: Irradiation window 7: Chamber 7a: Space inside the chamber 7b: Space within the chamber 8: Processing space 10: Xe Excimer Lamp 16: Gas supply pipe 17: Gas outlet 18: Loading entrance 19:Export exit 21: Subchamber 22: Subchamber 31: Nitrogen gas source 32: Oxygen-containing gas source 33: Gas mixer 34: Nitrogen gas source 35: Exhaust vent 40: Conveyor path 41: Conveyor roller 50: Electroless plating layer 51: Resin plating material 61: First storage tank 61a: Catalyst-granting liquid 62: Second storage tank 62a: Plating solution 65: Support member 66: Holder 70: Electroless plating equipment 71: Pre-processing unit 73: Catalyst treatment unit 75: Plating Unit 81: Ultrasonic generator 81a: Ultrasound 90: Low-pressure mercury lamp 100: Atmosphere L10: Ultraviolet light L90: Ultraviolet light

Claims

1. (a) A step of preparing a substrate containing an insulating resin material, (b) A step of irradiating the surface of the substrate with ultraviolet light with a wavelength of 200 nm or less in an atmosphere with an oxygen concentration of 0.01 volume% to 10 volume%, thereby modifying the area to be treated, including the surface of the substrate, into a microporous layer containing voids of the order of nanometers in size. (c) A step of bonding the catalyst to the microporous layer, A method for manufacturing a resin plating material, characterized by having a step (d) after step (c) in which an electroless plating layer is formed on the upper surface of the substrate via the catalyst.

2. A method for manufacturing a resin plated material according to claim 1, characterized in that ultrasonic vibrations are applied when performing step (d).

3. The method for manufacturing a resin plated material according to claim 1 or 2, characterized in that the processing target area is the area between the surface and a location that has progressed 3 nm to 50 nm in a depth direction perpendicular to the surface from the surface.

4. A method for producing a resin plating material according to claim 1 or 2, further comprising a step (e) after step (b) and before step (c) of removing low molecular weight components contained in the substrate, which have a lower molecular weight than the resin material constituting the substrate.

5. The method for manufacturing a resin plating material according to claim 4, characterized in that step (e) is a step of immersing the substrate after performing step (b) in an alkaline solution.

6. A pretreatment unit that irradiates a substrate containing an insulating resin material with ultraviolet light of a wavelength of 200 nm or less, A catalyst treatment unit includes a first storage tank in which a solution containing a catalyst is stored, and the substrate, after being irradiated with ultraviolet light by the pretreatment unit, is placed in the first storage tank. The system includes a plating treatment unit which includes a second storage tank in which a plating solution is stored, and which positions the substrate after it has been removed from the catalyst treatment unit into the second storage tank, The electroless plating apparatus is characterized in that the pretreatment unit includes a nitrogen gas source, and the oxygen concentration of the atmosphere in the irradiation area is adjusted to 0.01 volume% to 10 volume% by introducing nitrogen from the nitrogen gas source into the irradiation area to which the ultraviolet light is irradiated, and the ultraviolet light is irradiated onto the substrate located in the irradiation area.

7. The electroless plating apparatus according to claim 6, wherein the plating treatment unit includes an ultrasonic generator capable of transmitting ultrasonic waves to the plating solution in the second storage tank, and the substrate, after being removed from the catalyst treatment unit, is positioned in the second storage tank while ultrasonic waves generated from the ultrasonic generator are transmitted to the plating solution.

8. The system includes a transport path connecting the pretreatment unit, the catalyst treatment unit, and the plating treatment unit. The electroless plating apparatus according to claim 6 or 7, characterized in that the substrate moves along the transport path while the processes in the pretreatment unit, the catalyst treatment unit, and the plating treatment unit are performed.

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