JP6925814B2 - Resin and resin manufacturing method - Google Patents

Description

The present invention relates to a resin used for forming a printed circuit or a device circuit, and a method for producing the same.

Fluororesin has a low dielectric constant, excellent high frequency characteristics, and excellent heat resistance and electric resistance. Therefore, a printed circuit and a device circuit are provided together with resins such as polyimide resin, polyester resin, polyolefin resin, and epoxy resin. It is expected to be used not only in circuit boards mounted on various electric and electronic devices such as industrial machines, automobiles, communication devices, and home appliances, but also in more markets in the future.

As a method for forming a conductor layer on these resin surfaces, the following methods have been conventionally proposed. That is, a rolling bonding method (see, for example, Patent Document 1) in which a Cu foil having a roughened surface is bonded to a resin substrate by thermal rolling, and a copper sputtering method (for example, a patent) in which a Cu layer is formed by using a vacuum plasma film forming technique. Reference 2).

Japanese Unexamined Patent Publication No. 2014-1988885 Japanese Unexamined Patent Publication No. 2012-169412

However, since the rolling and bonding method uses an expensive Cu foil, the material cost is high. In addition, it is difficult for a substrate manufacturer to produce Cu foil in-house, and it cannot be said that it is suitable for procuring the required amount at the required timing.

Further, in the copper sputtering method, high-purity copper is used as the sputtering target, and copper is formed by high-vacuum plasma, so that the cost of the target and plasma equipment becomes high.

Therefore, instead of the rolling and bonding method and the copper sputtering method, it is conceivable to adopt a plating method that does not cost much. However, the plating method can be applied to epoxy resin or polyolefin resin substrates by using the anchor effect, but when the plating method is applied to fluororesin substrates, the fluororesin has chemical stability. Since the surface free energy is high (the surface free energy is small), the plating layer cannot be formed even if the anchor effect is used.

On the other hand, in addition to the increasing miniaturization and higher performance of electronic devices and semiconductor devices, users are demanding the development of circuit boards capable of high-speed transmission (high frequency) of electrical signals. In order to suppress the generation of noise due to high frequency, there is a demand for a substrate material in which the interface between a resin and a metal is flattened. Further, it is expected that a fluororesin, a polyimide resin, and a polyester resin having high heat resistance and insulating properties will be applied as the substrate material due to the increase in high frequency. However, a fluororesin having a flattened interface with a metal cannot form a plating layer.

Further, although the polyimide resin and the polyester resin can form a plating layer, they are easily damaged by the plating solution because the resin easily absorbs water and is weak in alkalinity. Therefore, the plating method cannot be adopted for these resins either.

Under these circumstances, these resins, especially fluororesins with high heat resistance and insulation (high frequency characteristics), are particularly required as substrate materials for highly reliable products such as communications, in-vehicle circuit boards, and radars in the future. , Expected. Further, in fields other than such communication-related fields, fluororesins are expected from the viewpoint of heat resistance.

However, as described above, the fluororesin has a small surface free energy and poor adhesion to the plating layer (conductor layer), so that it is essentially possible to obtain sufficient adhesion between the resin and the plating layer. difficult.

Therefore, according to the present invention, even if the plating method is applied to a resin having a small surface free energy such as a fluororesin and poor adhesion to the plating layer, sufficient adhesion between the resin and the plating layer can be secured. An object of the present invention is to provide a resin manufacturing technology capable of producing the same.

The formation of a plating layer using a plating method on the surface of an epoxy resin or the like is generally performed by the following method. That is, first, palladium (Pd) having excellent oxidation resistance is adsorbed on the surface of the resin by using a catalytic adsorption method. After that, when electroless plating or electrolytic plating of copper (Cu) is performed, Cu is precipitated by acting as a catalyst with Pd as a nucleus, and a plating layer having a predetermined thickness is formed.

As described above, the fluororesin whose interface with the metal is flattened cannot utilize the anchor effect, and because the surface free energy is small, it is poorly hydrophilic and has poor wettability to the plating solution. The interface between the fluororesin and the plating layer is not sufficiently adhered at the micro level.

Therefore, the present inventor can improve the wettability with the plating solution by increasing the surface free energy of the fluororesin, and can apply the plating method. Further, the fluororesin and palladium can be used. It is considered that if a functional group to be brought into close contact can be imparted to the resin surface, a sufficient adhesive force can be secured between the fluororesin and the plating layer, and as a means of doing so, a hydrophilic functional group is provided on the surface of the resin. I came up with the idea of surface modification of the resin to be introduced. That is, by introducing a hydrophilic functional group into the fluororesin, the adhesion between Pd, which is the core of the plating layer formation, and the fluororesin is increased, and the adhesion with the resin substrate is improved (conductor layer). I thought that I could form.

As a result of various experiments and studies, it was found that when an amino group was introduced as a hydrophilic functional group on the surface of the fluororesin, the adhesion to the plating layer was remarkably improved. When a high-frequency vacuum plasma is used to introduce the amino group, for example, in a fluororesin, the fluorine atom (F) connected to the carbon (C) atom serving as the skeleton is replaced with the amino group, and a sufficiently large number of amino groups are used. It turned out that can be introduced. Since a sufficiently large number of amino groups can be introduced, the surface free energy of the fluororesin becomes large, and the fluororesin can be made hydrophilic with respect to the catalyst solution. Furthermore, it was found that the adhesion was sufficiently improved by binding the amino group to a metal catalyst such as palladium. Further, it was found that the introduction of the amino group is suitable in terms of cost because it can be carried out under a moderate degree of vacuum without requiring a high vacuum. Then, it was found that this method can be applied not only to the above-mentioned fluororesin but also to all of the above-mentioned various resins, and the present invention has been completed. Since this method is a dry process and does not require treatment of waste liquid, it is possible to reduce costs with sufficient productivity.

That is, the present invention
A method for manufacturing a resin used for manufacturing a circuit board for high-speed communication in the GHz band.
A material gas containing an amino group is supplied into the chamber of the high-frequency decompression plasma apparatus to perform high-frequency decompression plasma treatment to generate plasma under a decompression of 1 to 100,000 Pa, and a carbon skeleton on the surface of the resin set in the chamber is performed. introducing said amino group comprises an amino group step of applying said resin, the surface roughness JIS B 0601-1982 in defined as the arithmetic average roughness Ra at 1μm or less of the fluorine resin der Ru resin It is a manufacturing method of.

In addition, the present invention
It is a resin in which an amino group is introduced and imparted to the carbon skeleton on the surface.

According to the present invention, even if the plating method is applied to a resin having a small surface free energy such as fluororesin and poor adhesion to the plating layer, sufficient adhesion between the resin and the plating layer can be ensured. It is possible to provide a resin manufacturing technique capable of producing the resin.

It is a figure which shows the manufacturing process of a resin substrate. It is a conceptual diagram which shows the carbon skeleton and the polymer chain in a fluororesin. It is a conceptual diagram which shows the reaction mechanism of amino group addition. It is a schematic diagram which shows an example of a high frequency plasma apparatus. It is a schematic diagram which shows an example of a high frequency plasma apparatus. It is a schematic diagram which shows an example of a high frequency plasma apparatus. It is a conceptual diagram which shows the precipitation state of Pd (upper part) and the precipitation mechanism of Cu by electroless plating (lower part). It is a conceptual diagram which shows the structure of the plating layer formed on the resin substrate. It is a perspective view which shows the test method of the plating strength peel test. It is an SEM image of the interface portion between a resin substrate and a Cu plating layer. It is an SEM image of the interface portion between a resin substrate and a Cu plating layer. It is an SEM image of the interface portion between a resin substrate and a Cu plating layer. It is an SEM image of the interface portion between a resin substrate and a Cu plating layer. It is an SEM image of the interface portion between a resin substrate and a Cu plating layer. It is a figure which shows the test result of the plating strength peel test. It is an SEM image of the Cu side peeling surface and the PTFE side peeling surface of a resin substrate. It is the XPS spectrum of the Cu side peeling surface and the PTFE side peeling surface of the resin substrate.

[Explanation of Embodiments of the Present Invention]
First, the contents of the embodiments of the present invention will be listed and described. In the following, a specific description will be given by taking the production of a circuit board as an example.

(1) The present invention
A method for manufacturing a resin used for manufacturing a circuit board for high-speed communication in the GHz band.
A material gas containing an amino group is supplied into the chamber of the high-frequency decompression plasma apparatus to perform high-frequency decompression plasma treatment to generate plasma under a decompression of 1 to 100,000 Pa, and a carbon skeleton on the surface of the resin set in the chamber is performed. introducing said amino group comprises an amino group step of applying said resin, the surface roughness JIS B 0601-1982 in defined as the arithmetic average roughness Ra at 1μm or less of the fluorine resin der Ru resin It is a manufacturing method of.

As described above, when an amino group is introduced as a hydrophilic functional group on the surface of the resin, the adhesion is remarkably improved. When a high-frequency vacuum plasma is used to introduce the amino group, for example, in a fluororesin, the fluorine atom (F) connected to the carbon (C) atom serving as the skeleton is replaced with the amino group, and a sufficiently large number of amino groups are used. Since the above can be introduced, the surface free energy of the resin is increased, and the adhesion is sufficiently improved. As a result, even if the plating method is applied to a resin having a small surface free energy such as fluororesin and poor adhesion to the conductor layer, the surface of the resin is made hydrophilic with respect to the plating solution, so that a metal catalyst, for example, Palladium is applied to the resin surface. Furthermore, since the adhesion is increased by the amino group binding to palladium, sufficient adhesion is secured between the resin and the plating layer (conductor layer), enabling high-speed transmission (high frequency) of electrical signals. Circuit board can be manufactured.

As a technique for introducing an amino group, in addition to the high-frequency decompression plasma described above, there is a wet treatment with metallic Na and ammonia, but the high-frequency decompression plasma can be treated by a dry process that does not generate waste liquid, so it is a simpler process. , And it can be processed at low cost, which is preferable.

(2) Then, in the present invention, the high-frequency low-pressure plasma treatment is preferably the high frequency low-pressure plasma treatment in which plasma is generated under a reduced pressure of 1～1000Pa.

By generating plasma under reduced pressure in the above range, a circuit board capable of high-speed transmission (high frequency) of electric signals by ensuring a sufficient adhesion between the resin and the plating layer (conductor layer) can be obtained. Can be manufactured.

(3) In the present invention, it is preferable to use ammonia or gaseous hydrazine as the material gas containing the amino group in the amino group addition step.

Since these gases have an amino group in the molecular structure, when these gases are used as the material gas, they can be ionized during plasma discharge to supply an amino group having high reaction activity to the resin surface. It is preferable. Among these gases, ammonia is particularly preferable because of its ease of handling.

(4) Further, in the present invention, the catalyst solution is brought into contact with the surface of the resin substrate to which the amino group is attached, and a metal catalyst for growing copper plating is applied to the surface of the resin substrate via the amino group. It is preferable to have a step of imparting.

When a metal catalyst is further applied to the surface of the resin to which the amino group is added by using high-frequency decompression plasma, the metal catalyst functions as a catalyst in the subsequent copper plating step, so that the metal catalyst has sufficient adhesion to the resin. The copper-plated layer having the above can be formed as a conductive layer.

Preferred metal catalysts include metal catalysts having a characteristic of autocatalytic ability to promote plating growth by redox reaction without using electricity, and specific examples thereof include palladium, nickel, and zinc.

(5) Further, in the present invention, it is preferable that the metal catalyst is palladium.

When the metal catalyst is palladium, a copper-plated layer having more sufficient adhesion to the resin can be formed as the conductive layer.
(6) Further, the present invention includes a copper plating step of forming an electroless plating layer and further forming an electrolytic copper plating layer having a predetermined thickness on the electroless plating layer by using electrolytic plating. It is preferable to have.

As described above, when the surface of palladium is electrolessly copper-plated, the palladium adheres to the amino group on the resin, so that sufficient adhesion to the electroless copper plating is exhibited. As a result, a copper-plated layer having a predetermined thickness can be efficiently formed on the resin substrate with sufficient adhesion as a conductive layer.

Conventionally, as a technique for forming a copper-plated layer on the surface of palladium, a graft method (Yu Sato et al., "Atmospheric pressure open type plasma", which improves adhesion with a copper-plated layer by growing another resin on a fluororesin Surface modification by treatment and polymer graft polymerization-Formation of Ag film on fluororesin- ", published on July 04, 2014, Proceedings of the Kansai Regional Periodic Academic Lecture of the Japan Society for Precision Engineering Volume: 2014 pp. 18-19 (See) and a direct plating method (see JP-A-2007-16283) in which electrolytic copper plating is performed directly on palladium.

However, the graft method is not a simple method because it requires two steps. On the other hand, electroless plating and electrolytic plating are preferable because a copper layer can be formed in one step.

Further, the direct plating method has a problem that the cost is high because the conductive layer is formed only with palladium. On the other hand, the technique according to the present embodiment uses a minimum amount of palladium and is preferable because it can be plated by an inexpensive copper plating process.

That is, Pd is excellent in catalysis and oxidation resistance, but is expensive and inferior in conductivity to copper. Therefore, it is preferable to reduce the amount of palladium used as much as possible and form a copper-plated layer having excellent conductivity on the layer. By doing so as described above, the amount of Pd used can be reduced and the material cost can be reduced. While suppressing it, it is possible to form a conductor layer having a predetermined conductivity with a thinner copper plating thickness.

(7) Further, in the present invention, the copper plating step is performed.
An electroless plating step of forming a copper plating layer by using electroless plating on the metal catalyst, and
It is preferable to have an electrolytic plating step of forming a copper plating layer by using electrolytic plating on a copper plating layer precipitated by electroless plating.

When forming a copper plating layer on palladium, the most efficient plating can be achieved if copper plating of the required thickness can be performed directly by electrolytic copper plating, but in reality, a palladium plating layer that can adsorb a large amount of palladium and allow current to flow. The amount of expensive palladium used is large and the cost is high.

Therefore, the minimum required amount of palladium is adsorbed on the resin surface, and electroless copper plating is grown from the palladium to perform electroless plating to a thickness at which conductivity can be obtained, and then switching to electrolytic plating is performed for plating. Therefore, a method of efficiently forming the copper plating layer is preferable for circuit formation from the viewpoint of cost. Further, it is preferable to perform a heat treatment after the plating treatment because the plating is stable.

Fluororesin, heat resistance a low dielectric constant and excellent power handling properties, Ru suitable der as the electrically insulating substrate of the printed circuit board.

By using a resin whose surface roughness Ra is smoothed to 1 μm or less as a substrate, it is possible to manufacture a circuit board sufficiently adaptable to high-speed transmission (GHz band).

( 8 ) The present invention
This is a method for manufacturing a circuit board in which a circuit board is manufactured using the resin manufactured by the above-mentioned resin manufacturing method.

By manufacturing a circuit board using the resin substrate manufactured by the above resin manufacturing method, a circuit board having a low dielectric constant and excellent heat resistance and electric resistance can be manufactured, and it can be sufficiently adapted to high-speed transmission. Circuit board can be provided.

( 9 ) The present invention
An amino group is introduced and imparted to the carbon skeleton of the surface, and the surface roughness is a fluororesin having an arithmetic average roughness Ra of 1 μm or less specified in JIS B 0601-1982 .

As described above, the resin in which an amino group is introduced and imparted to the carbon skeleton on the surface has a large surface free energy, and the adhesion to the conductive layer (copper plating layer) is sufficiently improved. Therefore, it is preferable as a resin for producing a circuit board which can be formed by closely adhering a conductive layer (copper plating layer) to the surface of the resin at a micro level without gaps and which can be sufficiently adapted to high-speed transmission.

As described above, the fluororesin has a low dielectric constant and is excellent in heat resistance and electric resistance, and is therefore suitable as a resin for an electrically insulating substrate of a printed circuit board.

( 10 ) Further, in the present invention, it is preferable that a metal catalyst is added on the amino group.

As described above, since the metal catalyst is applied, the metal catalyst can function as a catalyst during copper plating, and a plating layer having sufficient adhesion can be formed as a conductive layer.

( 11 ) Further, in the present invention, it is preferable that the metal catalyst is palladium.

By adding palladium, it is possible to make palladium exert a function as a catalyst during copper plating and to form a plating layer having more sufficient adhesion as a conductive layer.

( 12 ) Further, in the present invention, it is preferable that a copper plating layer having a predetermined thickness is formed on the palladium.

As described above, when a copper-plated layer is formed on palladium with a predetermined thickness, Pd acts as a catalyst to exert its function, and the copper-plated layer having a predetermined thickness is used as a conductive layer to provide sufficient adhesion to the resin substrate. It can be formed efficiently. Then, the amount of Pd used can be reduced to reduce the material cost, and an electrolytic copper plating layer having a predetermined conductivity can be formed on the electroless copper plating, and there is no gap on the surface of the resin at a micro level. The copper plating layer (conductive layer) can be formed in close contact with each other.

( 13 ) The present invention
It is a circuit board manufactured by using the resin.

Since the resin according to the present embodiment can form a copper-plated layer as a conductive layer with sufficient adhesion, it is possible to provide a circuit board sufficiently adaptable to high-speed transmission.

( 14 ) The present invention
It is a circuit board in which a circuit pattern is formed by using a copper plating layer formed on the surface of the resin.

By forming a circuit pattern using a copper-plated layer formed as a conductive layer having sufficient adhesion on a resin substrate, it is possible to provide a circuit board that can be sufficiently adapted to high-speed transmission.

[Details of Embodiments of the present invention]
Next, the details of the embodiment of the present invention will be described by taking the production of a circuit board as an example. In the following, palladium will be used as the metal catalyst, but the description is not limited to this.

1. 1. Outline of the circuit board manufacturing process First, the outline of the circuit board manufacturing process will be described. FIG. 1 is a diagram showing a manufacturing process of a circuit board. As shown in FIG. 1, in the production of a circuit board, first, an amino group is imparted to the surface of a resin (resin substrate) formed into a substrate by high-frequency reduced pressure plasma treatment, and the surface of the resin substrate is modified. .. Next, Pd is imparted to the surface of the resin substrate to which the amino group is imparted by catalytic adsorption. Next, the resin substrate to which Pd is imparted to the surface is _{immersed in a dilute sulfuric acid (H 2} SO ₄ ) solution to activate Pd. Finally, an electroless plating or a combination of electroless plating and electrolytic plating is used to form a Cu plating layer on the surface of the resin substrate.

2. Details of Manufacturing Circuit Boards Next, details of manufacturing circuit boards will be described in order of steps.

(1) Surface modification (amino group addition) step of the resin substrate (a) Preparation of the resin substrate First, the resin substrate is prepared.

As the resin substrate, a resin substrate conventionally used for manufacturing a printed circuit or a device circuit, or a resin substrate whose use is being considered in the future can be used.

Specifically, fluororesin substrates such as polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluorinated ethylene / hexafluoropropylene copolymer (FEP), and fragrance. Select from polyimide resin substrates such as group polyimide (PI) resin, polyester resin substrates such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resin substrates such as polypropylene (PP), and epoxy resin substrates. be able to.

At this time, it is preferable that the surface on the side to which the amino group is applied is subjected to a smoothing treatment in advance so that the surface roughness Ra is 1 μm or less. By smoothing the surface of the resin substrate in this way, it is possible to manufacture a circuit board that can be sufficiently adapted to high-speed transmission.

(B) High-frequency decompression plasma treatment (amino group addition) step In this step , amino-group plasma is generated by high-frequency decompression plasma treatment, and the generated plasma is used to replace the carbon skeleton on the surface of the resin substrate with fluorine. Introduce and impart amino groups in the form. FIG. 2A is a conceptual diagram showing a polymer chain of a fluororesin, and FIG. 2B is a conceptual diagram showing a reaction mechanism of amino group addition.

As shown in FIG. 2A, fluorine is bonded to the carbon skeleton in the fluororesin, but as shown in FIG. 2B, ammonia gas is introduced and high-frequency decompression plasma treatment is performed to generate amino group plasma (NH _2-). When this is done, the fluorine bonded to the carbon skeleton is replaced and an amino group is introduced into the carbon skeleton and imparted (fluorine becomes HF and leaves the carbon skeleton).

In the above, the amino group plasma ^{introduces ammonia gas at a flow rate of 1 sccm (standard cm 3} / min) or more, and in an atmosphere where the process pressure is maintained at 1 to 1,000 Pa, a high frequency of 1 to 100 MHz is 0. It is produced by applying at a power density of .01 to 3 W / cm ² and performing high-frequency depressurized plasma treatment.

As the high-frequency plasma processing device, a high-frequency plasma processing device capable of simultaneously processing a plurality of resin substrates by one plasma treatment is preferably used. 3A, 3B, and 3C are schematic views showing an example of a high-frequency plasma apparatus. In FIGS. 3A and 3B, 1 is a high frequency plasma device, 2 is a high frequency power supply device, 3 is a vacuum chamber, 4 is a process gas supply device, 5 is a vacuum exhaust device, and 6 is a vacuum exhaust device. It is a resin substrate of a plasma processing object.

As shown in FIGS. 3A and 3B, the high-frequency plasma apparatus has at least a RIE mode in which the resin substrate 6 which is a plasma processing object is arranged on the cathode side as a plasma mode. A mixed gas of a rare gas and an amino group-containing gas (for example, the above-mentioned ammonia gas) can be introduced into the vacuum chamber 3 by the process gas supply device 4, and plasma is formed in the atmosphere of the mixed gas. ..

As described above, the high-frequency plasma device 1 introduces ammonia gas at a flow rate of 1 sccm or more, and under an atmosphere in which the process pressure is maintained at 1 to 1,000 Pa, a high frequency of 1 to 100 MHz is 0.01 to 3 W / cm ² Amino group plasma can be generated by applying high-frequency reduced pressure plasma treatment by applying at the power density of. Since a high frequency, which is lower in frequency than microwaves, is applied, the active species (plasma) are likely to be accelerated, the kinetic energy of the active species becomes large, and the average free process is performed with respect to the resin substrate 6 which is the object of plasma processing. It can be irradiated with long active species.

In particular, in the RIE mode, unlike the PE mode, the resin substrate 6 exposed to high-frequency plasma is maintained below the heat-resistant temperature of the resin substrate, and the surface treatment is performed with a sheath layer in which the active species (amino group) vibrates in the vertical direction. Therefore, the amino group can be efficiently introduced and added to the carbon skeleton.

At this time, the gas pressure P is adjusted in the range of at least 1 to 1,000 Pa, and the plasma power density W is adjusted in the range of at least 0.01 to 3 W / cm ² .

(2) Addition of Pd (precipitation of Pd) and activation step of Pd In this step, Pd is precipitated on the surface of the resin substrate to which the amino group is imparted to the surface in the above step.

Known catalyst adsorption is used to impart Pd. Specifically, for example, a method of imparting Pd by adsorbing nanometer-sized Pd-Sn colloidal particles (nanoparticles) using a catalyst-acceleration method can be mentioned.

The upper part of FIG. 4 is a conceptual diagram showing the precipitation state of Pd. As shown in the upper part of FIG. 4, these nanoparticles are strongly adsorbed on the amino group by Sn.

Next, it is immersed in an active liquid such as dilute sulfuric acid to elute Sn on the surface side to expose Pd and activate the function as a catalyst for electroless plating Cu. As a result, as shown in the lower part of FIG. 4, Pd having a thickness close to the ideal is formed in a state of being firmly adhered to the surface to be plated.

(3) Forming Step of Cu Plating Layer In this step, a Cu plating layer is formed on the surface of the resin substrate whose surface is activated in the above. The Cu plating layer is formed by electroless plating or a combination of electroless plating and electrolytic plating.

(A) Electroless plating Cu electroless plating is performed using a known plating method. Specifically, for example, in an alkaline bath using formaldehyde as a reducing agent, a plating bath containing Rochelle salt and EDTA as a complexing agent and whose pH is adjusted with NaOH is used, for example, plating is performed at a bath temperature of 10 to 80 ° C. As a result, as shown in the lower part of FIG. 4, Cu is precipitated with Pd as a core, and a Pd—Cu plating layer is formed. Note that FIG. 4 is a conceptual diagram showing a Cu precipitation mechanism by electroless plating.

(B) Electrolytic plating Next, if necessary, Cu plating is performed on the Pd-Cu plating layer using electrolytic plating. Electrolytic plating of Cu is performed using a known plating method. For example, a plating method generally used for strike plating on non-electrolytic (chemical) plating, specifically, an acidic plating bath containing copper sulfate is used, and the current density is 3 at a bath temperature of 15 to 30 ° C. Plating at ~ 6A / dm ² . As a result, as shown in FIG. 5, a resin substrate in which an electroless Cu plating layer and a Cu plating layer are sequentially formed on a PTFE resin substrate via Pd can be obtained. Note that FIG. 5 is a conceptual diagram showing the configuration of the plating layer formed on the resin substrate.

3. 3. Manufacture of Circuit Board A circuit board is manufactured by forming a circuit pattern by subjecting the conductive layer (copper plating layer) formed on the resin substrate obtained above to a method such as etching. At this time, since the conductive layer has sufficient adhesion to the resin substrate, it is possible to form a circuit pattern with high accuracy, and it is possible to provide a circuit board that can be sufficiently adapted to high-speed transmission. ..

Hereinafter, the present invention will be described in more detail based on Examples.

1. 1. Experiment 1
In this experiment, a resin substrate having a Cu plating layer having a thickness of 30 μm formed on a PTFE resin substrate having a surface roughness Ra of 0.5 μm was produced by using the above-mentioned plating method, and the plating peel strength was measured. , The degree of adhesion was examined by observing the cross section of the interface between the resin substrate and the plating layer.

[1] Preparation of Resin Substrate A resin substrate on which a conductive layer was formed was manufactured by the following procedure according to each step shown in FIG.

(1) Preparation of Resin Substrate First, as a resin substrate, a resin substrate made of PTFE resin having a surface roughness Ra smoothed to 0.5 μm was prepared in advance.

(2) Surface Modification of Resin Substrate (Amino Group Addition) Next, under the plasma treatment conditions shown in Table 1, amino groups are imparted to the surface of the resin substrate by high-frequency reduced pressure plasma treatment to modify the surface of the resin substrate. Quality treatment was performed.

(3) Formation of Pd (precipitation of Pd)
Next, Pd was precipitated on the surface of each resin substrate to which the amino group was added by catalytic adsorption.

(4) Dilute Sulfuric Acid Immersion Activation Step After that, the resin substrate on which Pd was precipitated on the surface was immersed in a dilute sulfuric acid (H ₂ SO ₄ ) solution to activate Pd. Here, the catalyst was adsorbed by Sn-Pd colloidal plating.

(5) Step of Forming Cu Plating Layer Finally, a Cu plating layer was formed on the surface of the resin substrate by electroless plating.

Table 2 shows the procedures for electroless plating of Pd (Sn-Pd colloid plating: palladium catalyst adsorption), electroless plating of Cu, and electrolytic plating.

[2] Test method and results (1) Degree of adhesion The SEM images of the interface between the resin substrate and the Cu plating layer are shown in FIGS. 7A to 7E. From FIGS. 7A to 7E, it was confirmed that the resin substrate and the Cu plating layer were in close contact with each other at a micro level without any gaps.

Note that FIG. 7B is an SEM image in which the portion of region B in FIG. 7A is magnified 3000 times, and FIG. 7C is an SEM image in which the portion of region B in FIG. 7A is magnified 8000 times. Further, FIG. 7D is an SEM image in which the portion of region A in FIG. 7A is magnified 3000 times, and FIG. 7E is an SEM image in which the portion of region A in FIG. 7A is magnified 8000 times.

(2) Plating peel strength The plating peel strength test conforms to JIS Z 0237-2009, and after fixing each test sample S on the horizontal table of the test apparatus 8 as shown in FIG. 6, it is applied to the plating layer. Two parallel cuts were made at predetermined intervals (test piece width), and one end of the plating layer sandwiched between the cuts was sandwiched by a chuck and pulled upward. Specific test conditions are shown in Table 3.

As a result of the peel strength test, the resin substrate could not be produced by the conventional plating method, whereas according to the present invention, the resin substrate can be produced by the plating method, and the peel strength is 3. It was found to be 0 N / cm. Then, it was confirmed that the resin substrate and the Cu plating layer were in close contact with each other at a micro level without any gaps.

2. Experiment 2
[1] Preparation of resin substrate Based on the results of Experiment 1, the conditions for plasma treatment were set. Specifically, the processing pressure and the processing power were expanded to 30 to 70 Pa and 500 to 1000 W, respectively, and plasma treatment was performed to prepare a resin substrate.

Specifically, a resin substrate was prepared in the same manner as the plasma processing conditions in Table 1 except that the processing pressure was 30 Pa and the processing power was 500 W (0.13 W / cm ^2). Further, each of processing power 500W at process pressure ^{50Pa (0.13W / cm 2),} 750W (0.16W / cm 2), except that a 1000W (0.26W / cm ²⁾ and the plasma treatment conditions of Table 1 A resin substrate was produced in the same manner. Further, each of processing power 500W at process pressure ^{70Pa (0.13W / cm 2),} 750W (0.16W / cm 2), except that a 1000W (0.26W / cm ²⁾ and the plasma treatment conditions of Table 1 A resin substrate was produced in the same manner.

[2] Test method and test results

The results of the peel strength test are shown in FIG. 8 together with the results of Experiment 1. From FIG. 8, it was found that the peel strength was 1.0 N / cm or more and reached a plateau at 3.0 N / cm. Next, the peeled surface was observed to investigate the peeling mechanism between the resin substrate and the plating layer.

9 and 10 are SEM images and XPS spectra of the Cu-side peeling surface and the PTFE-side peeling surface of the resin substrate, respectively. In FIGS. 9 and 10, it was confirmed that CF (cohesive fracture) was present on the peeled surface on the Cu side. This result indicates that the PTFE was broken at the time of peeling, and from this result, the resin substrate was broken even though the resin substrate and the Cu plating layer were in close contact with each other with a strength exceeding the breaking strength of the resin substrate. It was found that the peel strength had reached a plateau.

3. 3. Experiment 3
On the other hand, in the case of a printed circuit board, a peel strength of 6.5 N / cm or more is generally preferable. Therefore, a resin substrate was prepared using a resin substrate made of PFA having a stronger strength, and the peel strength was examined. Specifically, a resin substrate having a Cu plating layer having a thickness of 30 μm formed on a PFA resin substrate having a surface roughness Ra of 0.2 μm was produced by using the plating method described in Experiment 1, and the plating peel strength was measured. bottom.

[1] Preparation of Resin Substrate Table 4 shows the plasma treatment conditions.

Table 5 shows the procedures for forming Pd (Sn-Pd colloid: palladium-catalyzed adsorption), electroless plating of Cu, and electrolytic plating.

[2] Test method and result The number of samples was set to 3, and the plating peel strength test was carried out by the same method as in Experiment 1. The width of the test piece was 5 mm. The test results are shown in Table 6. The test results were converted into 1 cm width and shown.

From Table 6, it was found that according to the present invention, a resin substrate plated with a peel strength that surely clears 6.5 N / cm, which is preferable for a printed circuit board, can be obtained.

4. Experiment 4
In this experiment, based on the results obtained in Experiments 1 to 3 described above, the adhesion between the resin substrate and the copper-plated layer in the resin substrate in which the copper-plated layer was formed on the various resin substrates shown in Table 7 was investigated. rice field. The surface roughness Ra of each resin substrate was set to 0.2 μm, and the thickness of the plating layer was set to 30 μm.

[1] Preparation of Resin Substrate Under the treatment conditions shown in Table 8, amino groups were added to the surface of each resin substrate prepared by high-frequency reduced pressure plasma treatment, and the surface modification treatment of each resin substrate was performed.

Then, in order to confirm that the resin was hydrophilized by the addition of the amino group, the change in the contact angle before and after the treatment in each resin was measured. The results are shown in Table 9.

From Table 9, it can be seen that the contact angle of each of the resins is small after the plasma treatment, and the hydrophilicity is improved (the surface free energy is large).

Next, according to the procedure shown in Table 10, Pd was applied and activated, and an electroless Cu plating layer was formed.

[2] Test method and test results By observing the surface of the prepared sample on the side where the copper plating layer was formed and checking for the presence or absence of defects where Cu has not been implanted, the resin substrate and the electroless copper plating layer The adhesion with was evaluated. The case where there was no defect was considered good.

In addition, the adhesive strength (tape peeling) was evaluated by the tape peeling method. Specifically, the cellophane tape was pressed against the plating layer, attached, and then peeled off, and at that time, the strength of adhesion was evaluated by examining whether or not the plating was peeled off. The case where it did not peel off was considered good.

The test results are shown in Table 11.

From Table 11, it was found that all the resins of PTFE, FEP, PI, PET, PEN, and PP had good adhesion and tape peeling, and the same results as in Experiments 1 to 3 were obtained for these resin substrates. By using these resin substrates, it is possible to provide a high-quality resin substrate with excellent adhesion between the resin substrate and the plating layer in electroless copper plating, and a circuit board that can be sufficiently adapted to high-speed transmission. Can be provided.

In the case of imide-based resin, polyester-based resin, and olefin-based resin, the water absorption rate is higher than that of fluororesin, and the fluororesin may be peeled off after plating due to a hydrolysis reaction with acid or alkali. For resins other than the above, more desirable results can be obtained by performing dry water removal treatment after electroless plating and electrolytic plating to ensure the adhesion strength.

5. Experiment 5
In this experiment, it was tested how the adhesion (peel strength) is improved when the polyimide resin in Experiment 4 described above is heated and dried after plating. The experimental conditions and the like other than heat-drying are the same as in Experiment 4 above.

(1) Heat-drying conditions Heat-drying: Performed twice, after electroless plating and after electrolytic plating Heat-drying conditions: 120 ° C. 30 minutes oven treatment

(2) Evaluation results Table 12 shows the evaluation results. The unit is N / cm.

From Table 12, when the polyimide resin was not heat-dried after plating, the peel strength was 0 N / cm because the resin absorbed water and peeled off at the interface, whereas it was heat-dried after plating. It was found that the peel strength was improved to 1.8 because such peeling due to water absorption did not occur, and it was confirmed that the polyimide resin needs to be heat-dried after electrolytic plating.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. Within the same and equal scope as the present invention, various modifications can be made to the above embodiments.

The resin substrate manufacturing technology shown in this embodiment is a printed circuit board suitable for high-speed transmission, and is a technology that enables the provision of a high-quality resin substrate having excellent adhesion between the resin substrate and the plating layer, and is of even higher quality. It can greatly contribute to the practical use of the circuit board.

1 High-frequency plasma device 2 High-frequency power supply device 3 Vacuum chamber 4 Process gas supply device 5 Vacuum exhaust device 6 Resin substrate 8 Test device A, B Area S Test sample

Claims (14)

A method for manufacturing a resin used for manufacturing a circuit board for high-speed communication in the GHz band.
A material gas containing an amino group is supplied into the chamber of the high-frequency decompression plasma apparatus to perform high-frequency decompression plasma treatment to generate plasma under a decompression of 1 to 100,000 Pa, and a carbon skeleton on the surface of the resin set in the chamber is performed. introducing said amino group comprises an amino group step of applying said resin, the surface roughness JIS B 0601-1982 in defined as the arithmetic average roughness Ra at 1μm or less of the fluorine resin der Ru resin Manufacturing method. The high-frequency vacuum plasma treatment, a manufacturing method of a resin according to claim 1, wherein the high-frequency low-pressure plasma treatment in which plasma is generated under a reduced pressure of 1～1000Pa. The method for producing a resin according to claim 1 or 2, wherein ammonia or gaseous hydrazine is used as the material gas containing the amino group in the amino group addition step. The first aspect of the present invention includes a step of bringing a catalyst solution into contact with the surface of the resin substrate to which the amino group is applied and imparting a metal catalyst for growing copper plating to the surface of the resin substrate via the amino group. The method for producing a resin according to any one of claims 3. The method for producing a resin according to claim 4, wherein the metal catalyst is palladium. The fourth or fifth aspect of the present invention, which comprises a copper plating step of forming an electroless plating layer and further forming an electrolytic copper plating layer having a predetermined thickness on the electroless plating layer by using electrolytic plating. Resin manufacturing method. An electroless plating step of forming a copper plating layer by using electroless plating on the metal catalyst, and
The method for producing a resin according to claim 6, further comprising an electrolytic plating step of forming a copper plating layer by using electrolytic plating on a copper plating layer precipitated by electroless plating. A method for manufacturing a circuit board, which manufactures a circuit board using the resin manufactured by the resin manufacturing method according to any one of claims 1 to 7. A fluororesin in which an amino group is introduced and imparted to the carbon skeleton on the surface, and the surface roughness is 1 μm or less in arithmetic average roughness Ra specified in JIS B 0601-1982 . The resin according to claim 9 , wherein a metal catalyst is added on the amino group. The resin according to claim 10 , wherein the metal catalyst is palladium. The resin according to claim 11 , wherein a copper-plated layer having a predetermined thickness is formed on the palladium. A circuit board manufactured by using the resin according to any one of claims 9 to 12. The circuit board according to claim 13 , wherein a circuit pattern is formed by using a copper-plated layer formed on the surface of the resin.

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