JP5399803B2 - Circuit board manufacturing method - Google Patents

Description

  The present invention relates to a circuit board and a method for manufacturing the circuit board.

  In mobile information terminal devices such as mobile phones, computers and peripheral devices, and electrical devices such as various information home appliances, high functionality is rapidly progressing. Accordingly, circuit boards mounted on these electric devices are required to have higher density of electric circuits. In order to satisfy such a demand for higher circuit density, there is a method capable of accurately forming wiring of an electric circuit with a narrower line width and line interval (width of a portion between adjacent electric circuits). It has been demanded. In high-density circuit wiring, short-circuiting or migration between wirings is likely to occur.

  As a method for manufacturing a circuit board, a method of forming an electric circuit on an insulating substrate by a subtractive method or an additive method is known. The subtractive method is a method of forming an electric circuit by removing (subtractive) a metal foil other than a portion where the electric circuit on the surface of the metal foil-clad laminate is desired to be formed. On the other hand, the additive method is a method of forming an electric circuit by performing electroless plating only on a portion where a circuit on an insulating substrate is to be formed.

  The subtractive method is a method in which the metal foil on the surface of the metal foil-clad laminate is etched to leave only the portion where the electric circuit is to be formed, and the other portion is removed. This method is disadvantageous from the viewpoint of manufacturing cost because the portion of the metal to be removed is wasted. On the other hand, in the additive method, metal wiring can be formed by electroless plating only in a portion where an electric circuit is desired to be formed. For this reason, metal is not wasted and resources are not wasted. Also from such a point, the additive method is a preferable circuit forming method.

  A method of forming an electric circuit made of metal wiring by a full additive method, which is one of conventional representative additive methods, will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view for explaining each step of forming a metal wiring by a conventional full additive method.

  First, as shown in FIG. 5A, a plating catalyst 102 is deposited on the surface of the insulating base material 100 on which the through holes 101 are formed. Note that the surface of the insulating substrate 100 is roughened in advance. Next, as shown in FIG. 5B, a photoresist layer 103 is formed on the insulating base material 100 on which the plating catalyst 102 is deposited. Next, as shown in FIG. 5C, the photoresist layer 103 is exposed through a photomask 110 on which a predetermined circuit pattern is formed. Next, as shown in FIG. 5D, the exposed photoresist layer 103 is developed to form a circuit pattern 104. Then, as shown in FIG. 5E, by performing electroless plating such as electroless copper plating, the metal wiring 105 is formed on the surface of the circuit pattern 104 and the inner wall surface of the through hole 101 formed by development. . By performing each process as described above, a circuit made of the metal wiring 105 is formed on the insulating base material 100.

  In the conventional additive method described above, the plating catalyst 102 is deposited on the entire surface of the insulating substrate 100. As a result, the following problems have arisen. That is, when the photoresist layer 103 is developed with high accuracy, plating can be formed only on a portion that is not protected by the photoresist. However, when the photoresist layer 103 is not developed with high accuracy, an unnecessary plated portion 106 may remain in a portion where the plating is not originally formed as shown in FIG. This occurs because the plating catalyst 102 is deposited on the entire surface of the insulating substrate 100. The unnecessary plated portion 106 causes a short circuit or migration between adjacent circuits. Such a short circuit or migration is more likely to occur when a circuit having a narrow line width and line interval is formed. FIG. 6 is a schematic cross-sectional view for explaining the contour shape of a circuit formed by a conventional full additive method.

  Moreover, as a manufacturing method different from the manufacturing method of said circuit board, the manufacturing method of patent document 1 and patent document 2 etc. are mentioned, for example.

  Patent Document 1 discloses the following method as another additive method.

  First, a solvent-soluble first photosensitive resin layer and an alkali-soluble second photosensitive resin layer are formed on an insulating substrate (insulating base material). Then, the first and second photosensitive resin layers are exposed through a photomask having a predetermined circuit pattern. Next, the first and second photosensitive resin layers are developed. Next, after the catalyst is adsorbed on the entire surface including the concave portions generated by development, only the unnecessary catalyst is removed by dissolving the alkali-soluble second photosensitive resin with an alkali solution. Then, after that, electroless plating is performed to accurately form a circuit only in a portion where the catalyst exists.

  Patent Document 2 below discloses the following method.

  First, a protective film of resin is coated on an insulating substrate (insulating base material) (first step). Next, a groove and a through hole corresponding to the wiring pattern are drawn or formed on the insulating substrate coated with the protective film alone or simultaneously by machining or laser beam irradiation (second step). Next, an activation layer is formed on the entire surface of the insulating substrate (third step). Next, the protective film is peeled off, the activation layer on the insulating substrate is removed, and the activation layer is left only on the inner wall surface of the groove and the through hole (fourth step). Next, the insulating substrate is plated without using a plating protective film, and a conductive layer is selectively formed only on the inner surfaces of the activated grooves and through holes (fifth step).

JP-A-57-134996 JP 58-186994 A

  However, according to the method described in Patent Document 1, two types of photosensitive resin layers having different solvent solubility are formed, and also during development, after developing with two types of solvent and adsorbing the catalyst, Furthermore, the manufacturing process is very complicated, such as the need to dissolve the second photosensitive resin with an alkaline solution.

  Patent Document 2 describes that after a thermosetting resin is coated on an insulating substrate as a protective film and heated and cured, the protective film and the insulating substrate are cut according to a predetermined wiring pattern, or the surface of the insulating substrate is heated. It is described that the curable resin is removed with a solvent (Patent Document 2, page 2, lower left column, line 16 to lower right column, line 11).

  About the thermosetting resin used as a protective film described in patent document 2, the kind in particular is not described. Since general thermosetting resins have excellent solvent resistance, there is a problem that they are difficult to remove with a simple solvent. Also, such a thermosetting resin has too high adhesion to the resin substrate, and it is difficult to accurately remove only the protective film without leaving a fragment of the protective film on the surface of the resin substrate. there were. In addition, when a strong solvent is used for sufficient peeling or when the substrate is immersed for a long time, the plating catalyst on the surface of the substrate is also removed. In this case, the conductive layer is not formed in the portion where the plating catalyst is removed. In addition, if a strong solvent is used or if it is immersed for a long time, the protective film made of thermosetting resin may collapse so that the plating catalyst in the protective film is redispersed in the solvent. there were. Thus, the plating catalyst redispersed in the solvent may be reattached to the surface of the resin base material, and an unnecessary plating film may be formed in that portion. Therefore, according to a method such as the method disclosed in Patent Document 2, it is difficult to form a circuit having an accurate contour.

  Further, when an electric circuit with a narrow line width and line interval is formed in order to realize high density of the electric circuit using the conventional methods for manufacturing various circuit boards as described above, the following problems occur. . That is, as the line width and the line interval of the circuit are reduced, there is a problem that the metal wiring constituting the electric circuit is easily peeled from the circuit groove of the insulating base material. Such peeling of the circuit can cause a decrease in the reliability of the electronic device.

  Specifically, a problem that may occur in an electric circuit board mounted on a portable information terminal device such as a cellular phone will be described as an example.

  A relatively large LSI (Large Scale Integration) is mounted on an electric circuit board mounted on a portable information terminal device. Such an LSI is bonded to the land portion formed as a part of the circuit of the electric circuit board by solder bumps. Since the portable information terminal device is carried, there are many opportunities to receive an impact. When such an impact is applied, there is a risk that a force is applied to the mounted LSI and the metal wiring constituting the land portion is peeled off from the insulating base material.

  Furthermore, as the line width and line interval of the circuit are narrowed, there is a problem that the strength of the metal wiring constituting the circuit is also reduced. In the above example, due to this, there is a possibility that the metal wiring constituting the land portion may be cut and damaged due to the force applied to the LSI mounted on the LSI.

  That is, as the line width and the line interval of the electric circuit are narrowed, there is a problem that the circuit is easily damaged as described above.

  In order to solve the above problems, the circuit wiring is widened, the metal wiring is reinforced, the contact area between the metal wiring and the insulating base is increased, and the metal wiring and the insulating base are in close contact with each other. A method for improving the sex can be considered. However, such a method cannot increase the density of the circuit.

  The present invention has been made in view of such circumstances, and even if the line width and the line interval of the electric circuit formed on the insulating substrate are narrow, the adhesion between the insulating substrate and the electric circuit is high, An object of the present invention is to provide a circuit board in which an electric circuit is hardly damaged. Moreover, it aims at providing the manufacturing method of the said circuit board.

  The present inventors paid attention to the composition of the insulating base material in order to improve the adhesion between the insulating base material and the electric circuit. When an insulating base material that does not contain a filler is used, it is considered that the surface of the circuit groove formed by laser processing or machining does not contain a filler, and therefore tends to be smooth. In general, a circuit groove with a smooth surface is considered to be easier to form an electric circuit, and a filler that can reduce the smoothness of the surface of the circuit groove formed by laser processing or machining is not included. It is done.

  However, when using an insulating base material that does not contain a filler, the present inventors may apply electroless plating after depositing a catalytic metal on the surface of a circuit groove formed on the insulating base material. The present inventors have found that a phenomenon occurs in which a plating layer to be an electric circuit is not formed on a circuit groove or a formed plating layer is peeled off.

  The present inventors have inferred that this phenomenon is due to the following.

  First, since the surface of the circuit groove was smooth, it was considered that even if a catalyst metal was deposited on the surface of the circuit groove, it did not adhere sufficiently and dropped off.

  Furthermore, since the insulating base material did not contain a filler, it was considered that the thermal expansion coefficient was large. Specifically, it was considered that the insulating base material was easily deformed due to temperature change, and the stress applied to the electric circuit due to the deformation exceeded the adhesive force between the electric circuit and the insulating base material.

  When the circuit groove is formed by laser processing or machining, since the insulating base material does not contain a filler, the heat resistance of the insulating base material is low, melting due to heat occurs, and the shape of the circuit groove is distorted. Thought to be. That is, it was considered that the stress applied to the electric circuit became non-uniform due to this irregular shape, and a portion where the stress applied to the electric circuit exceeded the adhesive force between the electric circuit and the insulating base was formed.

  Therefore, the present inventors have conceived the present invention as described below by intentionally containing a filler capable of reducing the smoothness of the surface of the circuit groove formed by laser processing or machining. It was.

  A circuit board according to one aspect of the present invention forms a resin film on a surface, and forms a circuit groove having a desired shape and depth by laser processing or machining from the outer surface side of the resin film, Applying a catalytic metal to the surface of the circuit groove and the surface of the resin coating, and applying the electroless plating to the insulating substrate formed by peeling the resin coating from the insulating substrate. And the insulating base material contains a filler.

  According to the above configuration, even if the line width and line interval of the electric circuit formed on the insulating base material are narrow, the circuit between the insulating base material and the electric circuit has high adhesion and the electric circuit is not easily damaged. A substrate is obtained. In addition, the said electric circuit is specifically formed on the circuit groove | channel of an insulating base material by giving the said electroless plating.

  The effect of increasing the adhesion between the insulating base and the electric circuit described above is presumed to be due to the following mechanism.

  First, when forming the circuit groove, it is considered that the surface of the formed circuit groove is formed with minute irregularities derived from the filler by performing laser processing or machining on the insulating substrate. And, it is considered that the catalyst metal deposited on the surface of the circuit groove can be sufficiently suppressed by the minute unevenness. Therefore, it is considered that the occurrence of defects in the electric circuit formed on the circuit groove can be sufficiently suppressed by electroless plating.

  Furthermore, it is considered that the adhesion between the electric circuit formed on the circuit groove of the insulating base material and the insulating base material can be enhanced by the anchor effect due to the minute unevenness.

  Moreover, since the said insulating base material contains a filler, a thermal expansion coefficient becomes small. Therefore, the insulating base material is not easily deformed by a temperature change, and stress applied to the formed electric circuit is reduced. Therefore, it is considered that peeling of the electric circuit due to the stress applied to the electric circuit due to the deformation can be suppressed.

  Furthermore, when the circuit groove is formed by laser processing or machining, since the insulating base material contains a filler, the insulating base material has high heat resistance and is not easily melted by heat. Therefore, it is considered that the shape of the formed circuit groove can be sufficiently suppressed. That is, since it is suppressed that the shape of the circuit groove is distorted, it is considered that the stress applied to the electric circuit becomes uniform and peeling of the electric circuit can be suppressed.

  From the above, even if the line width and the line interval of the electric circuit formed on the insulating base material are narrow, a circuit board having high adhesion between the insulating base material and the electric circuit and being difficult to damage the electric circuit can be obtained. it is conceivable that.

  Moreover, it is preferable that content of the said filler is 10-90 mass% with respect to the said insulating base material. According to such a configuration, even if the line width and the line interval of the electric circuit are narrow, a circuit board with higher adhesion between the insulating base and the electric circuit can be obtained.

  Moreover, it is preferable that the average particle diameter of the said filler is 0.05-10 micrometers. According to such a configuration, even if the line width and the line interval of the electric circuit are narrow, a circuit board with higher adhesion between the insulating base and the electric circuit can be obtained.

  The average particle diameter of the filler is 0.25 with respect to the minimum value among the width of the circuit groove, the depth of the circuit groove, and the width of the portion between adjacent circuit grooves. It is preferably ˜50%. According to such a configuration, even if the line width and the line interval of the electric circuit are narrow, a circuit board with higher adhesion between the insulating base and the electric circuit can be obtained.

  The filler is preferably inorganic fine particles. According to such a configuration, even if the line width and the line interval of the electric circuit are narrow, a circuit board with higher adhesion between the insulating base and the electric circuit can be obtained. This is considered to be able to make a larger contribution due to the fact that, among the above mechanisms, for example, the thermal expansion coefficient of the insulating base material can be made smaller. That is, the insulating base material is less likely to be deformed due to the temperature change, and the stress applied to the formed electric circuit is reduced. Therefore, it is considered that the peeling of the electric circuit due to the stress applied to the electric circuit due to the deformation can be further suppressed.

  Further, it is preferable that the electric circuit includes a portion having a line width of at least 5 to 30 μm. In the case of an electric circuit including a portion having such a narrow line width, a circuit board having a sufficiently dense circuit can be obtained. In the case of such an electric circuit having a narrow line width, generally, the contact area between the electric circuit and the insulating substrate is narrow, the adhesion between the electric circuit and the insulating substrate is lowered, and the electric circuit is insulated from the insulating substrate. Easy to peel from the material. By adopting the above configuration, even in the case of an electric circuit with a narrow line width as described above, the adhesion between the electric circuit and the insulating base is sufficiently high, and the electric circuit from the insulating base is A circuit board capable of suppressing peeling is obtained.

  A circuit board manufacturing method according to another aspect of the present invention includes a film forming step of forming a resin film on the surface of an insulating base, and laser processing or mechanical processing on the insulating base from the outer surface side of the resin film. A circuit groove forming step of forming a circuit groove having a desired shape and depth by processing; a catalyst deposition step of depositing a catalyst metal on the surface of the circuit groove and the surface of the resin coating; and the insulating base material A coating peeling process for peeling the resin coating from the coating, and a plating treatment process for electroless plating on the insulating substrate from which the resin coating has been peeled. The coating forming step contains a filler as the insulating substrate. It is characterized by using what to do.

  According to the above configuration, even when an electric circuit with a narrow line width and line interval is formed on an insulating substrate, the circuit with high adhesion between the insulating substrate and the electric circuit and the electric circuit is not easily damaged. A substrate can be manufactured.

  ADVANTAGE OF THE INVENTION According to this invention, even if the line | wire width and line space | interval of the electric circuit formed on an insulating base material are narrow, a circuit board with high adhesiveness of an insulating base material and an electric circuit can be provided. A method for manufacturing the circuit board is also provided.

It is a schematic cross section for explaining each process of manufacturing a circuit board concerning a 1st embodiment. In 1st Embodiment, it is drawing for demonstrating the state of the insulating base material 1 after the said circuit groove formation process and the said plating process. It is drawing for demonstrating the state of the insulation base material 21 at the time of using the insulation base material 21 which does not contain a filler. It is a schematic cross section for explaining each process of manufacturing a three-dimensional circuit board concerning a 2nd embodiment. It is a schematic cross section for demonstrating each process of forming the metal wiring by the conventional full additive method. It is a schematic cross section for demonstrating the outline shape of the circuit formed by the conventional full additive method.

  Hereinafter, although the embodiment concerning the present invention is described, the present invention is not limited to these.

  The circuit board according to the present embodiment forms a circuit groove having a desired shape and depth by forming a resin film on the surface and laser processing or machining from the outer surface side of the resin film. Formed by depositing a catalytic metal on the surface of the resin and the surface of the resin coating, and peeling the resin coating from the insulating substrate, and applying electroless plating to the insulating substrate And the insulating base material contains a filler.

(First embodiment)
First, a method for manufacturing a circuit board according to the first embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view for explaining each step of manufacturing the circuit board according to the first embodiment.

  First, as shown in FIG. 1A, a resin coating 2 is formed on the surface of the insulating base 1. This process corresponds to a film forming process. The insulating substrate 1 contains a filler. Specifically, for example, a base material containing a resin and a filler can be used.

  Next, as shown in FIG. 1B, a desired shape and depth are obtained by laser processing or machining the insulating base material 1 on which the resin coating 2 is formed from the outer surface side of the resin coating 2. The circuit groove 3 is formed. The laser processing or machining for forming the circuit groove 3 is performed by cutting beyond the thickness of the resin coating 2 on the basis of the outer surface of the resin coating 2. Moreover, you may drill the hole for forming the through-hole 4 in the said insulating base material 1 as needed. This step corresponds to a circuit groove forming step.

  Next, as shown in FIG. 1C, a catalyst metal (plating catalyst) 5 is deposited on the surface of the circuit groove 3 and the surface of the resin film 2 where the circuit groove 3 is not formed. At this time, when the through hole 4 is formed in the insulating base material 1, the catalytic metal 5 is also deposited on the inner wall surface of the through hole 4. This step corresponds to a catalyst deposition step.

  Next, as shown in FIG. 1D, the resin film 2 is peeled from the insulating base material 1. By doing so, the catalyst metal 5 can remain only on the surface of the insulating substrate 1 where the circuit grooves 3 and the through holes 4 are formed. On the other hand, the catalytic metal 5 deposited on the surface of the resin film 2 is removed together with the resin film 2 while being supported on the resin film 2. This process corresponds to a film peeling process.

  Next, as shown in FIG. 1E, electroless plating is performed on the insulating base material 1 from which the resin film 2 has been peeled off. By doing so, the plating layer 6 is formed only in the portion where the catalyst metal 5 remains. That is, the plating layer 6 which becomes an electric circuit is formed in the portion where the circuit groove 3 and the through hole 4 are formed. The electric circuit may be composed of the plating layer 6 or may be a film obtained by further applying electroless plating (fill-up plating) to the plating layer 6 to make it thicker. . Specifically, for example, as shown in FIG. 1 (E), an electric circuit made of a plating layer 6 is formed so as to fill the entire circuit groove 3, and a step between the insulating substrate and the electric circuit is eliminated. You may do it. This process corresponds to a plating process.

  Through the above steps, a circuit board 10 as shown in FIG. 1E is formed. The circuit board 10 thus formed has high adhesion between the insulating substrate and the electric circuit even if the line width and the line interval of the electric circuit formed on the insulating substrate are narrow, and the electric circuit is damaged. Hateful.

  The effect of increasing the adhesion between the insulating base and the electric circuit described above is presumed to be due to the following mechanism.

  In addition, FIG. 2 is drawing for demonstrating the state of the insulation base material 1 after the said circuit groove formation process and the said plating process in 1st Embodiment. 2A shows the state of the insulating base material 1 after the circuit groove forming step, and FIG. 2B shows the state of the insulating base material 1 during the plating process.

  First, as shown in FIG. 2 (A), the insulating substrate 1 after the circuit groove forming step is formed with the circuit groove 3 by subjecting the insulating substrate 1 to laser processing or machining. Then, on the surface of the circuit groove 3, as shown in FIG. 2A, the filler 11 contained in the insulating base material 1 is partially exposed, or a bulge based on the filler 11 is formed. I think that. Therefore, it is considered that minute irregularities derived from the filler 11 are formed on the surface of the circuit groove 3. Then, it is considered that the catalyst metal deposited on the surface of the circuit groove 3 by the catalyst deposition step is unlikely to fall off due to the minute unevenness.

  Thereafter, after the resin film 2 is peeled off by the film peeling step, an electrocircuit is formed on the circuit groove 3 as shown in FIG. 2B by performing electroless plating in the plating treatment step. A plating layer 7 is formed. This plating layer 7 is considered to be able to be formed while sufficiently suppressing the occurrence of defects since the falling of the catalytic metal deposited on the surface of the circuit groove 3 is suppressed.

  Furthermore, it is considered that the adhesion between the electric circuit formed on the circuit groove of the insulating base material and the insulating base material can be enhanced by the anchor effect due to the minute unevenness.

  Moreover, since the said insulating base material contains a filler, a thermal expansion coefficient becomes small. Therefore, the insulating base material is not easily deformed by a temperature change, and stress applied to the formed electric circuit is reduced. Therefore, it is considered that peeling of the electric circuit due to the stress applied to the electric circuit due to the deformation can be suppressed.

  Furthermore, when the circuit groove is formed by laser processing or machining, since the insulating base material contains a filler, the insulating base material has high heat resistance and is not easily melted by heat. Therefore, it is considered that the shape of the formed circuit groove can be sufficiently suppressed. That is, since it is suppressed that the shape of the circuit groove is distorted, it is considered that the stress applied to the electric circuit becomes uniform and peeling of the electric circuit can be suppressed.

  From the above, even if the line width and the line interval of the electric circuit formed on the insulating base material are narrow, a circuit board having high adhesion between the insulating base material and the electric circuit and being difficult to damage the electric circuit can be obtained. it is conceivable that. That is, even if the plated layer 7 is subjected to fill-up plating, the obtained electric circuit is considered to be hardly peeled off from the insulating substrate.

  On the other hand, when the insulating base material 21 containing no filler is used, even if the electric circuit is formed by the same method as in this embodiment, the plating layer that becomes the electric circuit is formed on the circuit groove. The present inventors have found that there is a phenomenon in which no part or formed plating layer is peeled off. It is assumed that it is as follows.

  In addition, FIG. 3 is drawing in order to demonstrate the state of the insulation base material 21 at the time of using the insulation base material 21 which does not contain a filler. 3A and 3B are drawings corresponding to FIGS. 2A and 2B, respectively.

  First, since the surface of the circuit groove 23 formed on the insulating base material 21 is smooth by laser processing or machining, even if a catalyst metal is applied to the surface of the circuit groove 23, it is not sufficiently applied. , Is considered to fall out.

  Thereafter, even if electroless plating is performed after the resin film 22 is peeled off, the circuit is caused by a portion where the catalytic metal is not deposited on the surface of the circuit groove 23 as shown in FIG. It is considered that a portion 23 a where the plating layer 25 to be an electric circuit is not formed on the groove 23 is formed.

  Moreover, since the insulating base material 21 does not contain a filler, the coefficient of thermal expansion is increased. Therefore, the insulating base material 21 is easily deformed due to a temperature change, and the stress applied to the plating layer 25 due to the deformation exceeds the adhesive force between the plating layer 25 and the insulating base material 21, and the plating layer 25 is peeled off. It is considered that 25a is formed.

  When the circuit groove 23 is formed by laser processing or mechanical processing, since the insulating base material 21 does not contain a filler, the heat resistance of the insulating base material 21 is low, and melting due to heat occurs. The shape of this is thought to be distorted. Therefore, the stress applied to the plating layer 25 becomes non-uniform due to this irregular shape, and a portion where the stress applied to the plating layer 25 exceeds the adhesion between the plating layer 25 and the insulating substrate 21 can be formed. It is considered that a portion 25a from which 25 is peeled is formed.

  From the above, it is considered that the plating layer 25 to be an electric circuit is not formed on the circuit groove 23 of the insulating base material 21 or peels off. That is, it is considered that when the plated layer 25 is further subjected to fill-up plating, the obtained electric circuit is more easily peeled from the insulating base material 21.

  Hereinafter, each configuration of the present embodiment will be described.

  The insulating substrate 1 contains a filler. Specifically, for example, a base material containing a resin and a filler can be used.

  The resin can be used without particular limitation as long as it is a resin constituting various organic substrates that can be used in the manufacture of circuit boards. Specifically, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, a polyphenylene sulfide resin, and the like can be given.

  The epoxy resin is not particularly limited as long as it is an epoxy resin constituting various organic substrates that can be used for manufacturing a circuit board. Specifically, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, aralkyl epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin , Dicyclopentadiene type epoxy resins, epoxidized products of condensates of phenols and aromatic aldehydes having phenolic hydroxyl groups, triglycidyl isocyanurate, finger ring type epoxy resins and the like. Furthermore, in order to impart flame retardancy, the above-mentioned epoxy resin or the like that is brominated or phosphorus-modified is also included. Moreover, as said epoxy resin, said each epoxy resin may be used independently, and may be used in combination of 2 or more type.

  Moreover, when comprising a base material with said each resin, in order to make it harden | cure, a hardening | curing agent is generally contained. The curing agent is not particularly limited as long as it can be used as a curing agent. Specific examples include dicyandiamide, phenolic curing agents, acid anhydride curing agents, aminotriazine novolac curing agents, and the like. As said phenol type hardening | curing agent, a novolak type, an aralkyl type, a terpene type etc. are mentioned, for example. Moreover, as said hardening | curing agent, said each hardening | curing agent may be used independently, and may be used in combination of 2 or more type.

  The filler may be inorganic fine particles or organic fine particles, and is not particularly limited.

Specific examples of the material constituting the inorganic fine particles include aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), boron nitride (BN), aluminum nitride (AlN), silica (SiO ₂ ), High dielectric constant fillers such as barium titanate (BaTiO ₃ ) and titanium oxide (TiO ₂ ); magnetic fillers such as hard ferrite; magnesium hydroxide (Mg (OH) ₂ ), aluminum hydroxide (Al (OH) ₂ ), Antimony trioxide (Sb ₂ O ₃ ), antimony pentoxide (Sb ₂ O ₅ ), guanidine salts, zinc borate, molybdate compounds, zinc stannate, and other inorganic flame retardants; talc (Mg ₃ (Si ₄ O ₁₀₎ (OH) 2), barium sulfate (BaSO _4), calcium carbonate (CaCO _3), mica, and the like. As said inorganic fine particle, the said inorganic fine particle may be used independently, and may be used in combination of 2 or more type. Since these inorganic fine particles have high thermal conductivity, relative dielectric constant, flame retardancy, particle size distribution, color tone freedom, etc., when selectively exerting a desired function, appropriate blending and particle size design should be performed. And high filling can be easily performed.

  The inorganic fine particles may be surface-treated with a silane coupling agent in order to improve dispersibility in the insulating base material. The insulating base material may contain a silane coupling agent in order to increase the dispersibility of the inorganic fine particles in the insulating base material. Specific examples of the silane coupling agent include epoxy silane, mercapto silane, amino silane, vinyl silane, styryl silane, methacryloxy silane, acryloxy silane, titanate silane couplings, and the like. Agents and the like. As said silane coupling agent, the said silane coupling agent may be used independently, and may be used in combination of 2 or more type.

  The insulating base material may contain a dispersant in order to enhance the dispersibility of the inorganic fine particles in the insulating base material. Specific examples of the dispersant include alkyl ether-based, sorbitan ester-based, alkyl polyether amine-based, polymer-based dispersants, and the like. As said dispersing agent, the said dispersing agent may be used independently, and may be used in combination of 2 or more type.

  Specific examples of the organic fine particles include rubber fine particles.

  Among the above fillers, the filler is preferable from the viewpoint that the inorganic fine particles can easily achieve a high filling and can exhibit the anchor effect due to the uneven shape. Furthermore, among these, in addition to the above effects, silica fine particles can exhibit low expansion, low moisture absorption, low dielectric constant, low dielectric loss tangent, high strength, high elastic modulus, etc., and increase heat resistance. It is preferable because it can be used. Moreover, when it is necessary to improve the heat dissipation of the circuit board obtained, it is preferable to contain not only silica particles but also alumina particles and aluminum hydroxide particles together with silica particles.

  It is preferable that content of the said filler is 10-90 mass% with respect to the said insulating base material, it is preferable that it is 30-90 mass%, and it is preferable that it is 60-90 mass%. When the content of the filler is within the above range, it approaches the linear expansion coefficient of an electric circuit, for example, an electric circuit made of Cu, and low warpage and low stress can be realized. Moreover, when there is too little content of the said filler, there exists a tendency which cannot fully suppress generation | occurrence | production of the part in which a plating layer is not formed, or peeling of a plating layer. This is considered to be due to the fact that the fine irregularities derived from the filler as described above are hardly formed on the surface of the circuit groove or the through hole. Moreover, when there is too much content of the said filler, the smoothness of an insulation base material will fall, Therefore, when peeling the resin film in a film peeling process, malfunctions, such as damaging an insulation base material, generate | occur | produce. Tend.

  The average particle diameter of the filler is preferably 0.05 to 10 μm, and more preferably 0.1 to 7 μm. The average particle diameter of the filler is 0 with respect to the minimum value among the width W of the circuit groove, the depth D of the circuit groove, and the width of the portion between adjacent circuit grooves. It is preferably 25 to 50%, more preferably 0.5 to 40%. Here, the average particle diameter means a volume average particle diameter, and can be measured using a general particle size meter, for example, a particle size meter (SALD2100 manufactured by Shimadzu Corporation).

  If the filler is too small, there is a tendency that generation of a portion where the plating layer is not formed and peeling of the plating layer cannot be sufficiently suppressed. This is considered to be due to the fact that the fine irregularities derived from the filler as described above are hardly formed on the surface of the circuit groove or the through hole. On the other hand, if the filler is too large, there is a tendency that a desired circuit groove cannot be formed when forming a circuit with higher density, for example, a circuit having a line width and a line interval of 10 μm or less. Furthermore, there is a tendency that generation of a portion where the plating layer is not formed and peeling of the plating layer cannot be sufficiently suppressed. This is considered to be because if the filler is too large, the fine irregularities derived from the filler as described above are hardly formed.

  The average particle diameter of the filler is preferably 0.05 to 3 μm when the width of the circuit groove (trench width) is 10 μm or less, and 0.05 to 3 when the trench width is more than 10 μm and 20 μm or less. It is preferably 5 μm, preferably 0.05 to 7 μm when the trench width exceeds 20 μm and 30 μm or less, and preferably 0.05 to 10 μm when the trench width exceeds 30 μm.

  Further, the same relationship as the trench width is satisfied with respect to the width (inter-trench width) of the portion between the adjacent circuit grooves and the depth of the circuit groove (trench depth).

  And the minimum value among the said trench width, the said width between trenches, and the said trench depth determines the suitable range of the average particle diameter of a filler. Specifically, for example, when all of the trench width, the inter-trench width, and the trench depth are 20 μm, a filler having an average particle diameter of 0.05 to 5 μm is preferably used. On the other hand, if the trench width and the inter-trench width are both 20 μm, a filler having an average particle diameter of 0.05 to 3 μm is preferably used if the trench depth is 10 μm.

  Further, the form of the insulating substrate is not particularly limited. Specifically, a sheet | seat, a film, a prepreg, a molded object of a three-dimensional shape etc. are mentioned. The thickness of the insulating substrate 1 is not particularly limited. Specifically, in the case of a sheet, film, or prepreg, for example, the thickness is preferably 10 to 200 μm, and more preferably about 20 to 100 μm.

  The resin film 2 is not particularly limited as long as it can be removed in the film peeling step. Specifically, for example, a soluble resin that can be easily dissolved by an organic solvent or an alkaline solution, a resin film made of a swellable resin that can be swollen by a predetermined liquid (swelling liquid) described later, and the like. Among these, a swellable resin film is particularly preferable because accurate removal is easy. Examples of the swellable resin film include a resin film that does not substantially dissolve in a predetermined liquid (swelling liquid), which will be described later, and easily peels from the surface of the insulating base material 1 by swelling. .

  A method for forming the resin coating 2 is not particularly limited. Specifically, for example, a liquid material is applied to the main surface of the insulating base material 1 and then dried, or the resin coating 2 such as a resin film previously formed on the main surface of the insulating base material 1 is formed. The method of bonding what is obtained is mentioned. The method for applying the liquid material is not particularly limited. Specifically, for example, conventionally known spin coating method, bar coater method and the like can be mentioned.

  The thickness of the resin coating 2 is preferably 10 μm or less, and more preferably 5 μm or less. On the other hand, the thickness of the resin coating 2 is preferably 0.1 μm or more, and more preferably 1 μm or more. When the thickness of the resin coating 2 is too thick, the accuracy of grooves and holes formed by laser processing or machining tends to decrease. Moreover, when the thickness of the resin film 2 is too thin, it tends to be difficult to form a resin film having a uniform film thickness.

  Next, a swellable resin film suitable as the resin film 2 will be described as an example.

  As the swellable resin film, a resin film having a swelling degree with respect to the swelling liquid of 50% or more can be preferably used. Further, a resin film having a degree of swelling with respect to the swelling liquid of 100% or more is more preferable, and a resin film having 1000% or less is more preferable. In addition, when the said swelling degree is too low, there exists a tendency for a swelling resin film to become difficult to peel in the said film peeling process. Moreover, when the said swelling degree is too high, there exists a tendency for peeling to become difficult by tearing at the time of peeling, etc., when the film strength falls.

  The method for forming the swellable resin film is not particularly limited. Specifically, for example, a liquid material capable of forming a swellable resin film is applied to the main surface of the insulating base material 1 and then dried, or the liquid material is applied to a support substrate and then dried. For example, a method of transferring the coating film formed on the main surface of the insulating substrate 1 may be used.

  Examples of the liquid material capable of forming the swellable resin film include elastomer suspensions and emulsions. Specific examples of the elastomer include a diene elastomer such as a styrene-butadiene copolymer, an acrylic elastomer such as an acrylate ester copolymer, and a polyester elastomer. According to such an elastomer, it is possible to easily form a swellable resin film having a desired degree of swelling by adjusting the degree of crosslinking or gelation of the elastomer resin particles dispersed as a suspension or emulsion.

  The swellable resin film is particularly preferably a film whose degree of swelling changes depending on the pH of the swelling liquid. When such a coating is used, the liquid condition in the catalyst deposition step is different from the liquid condition in the coating stripping step, so that a swellable resin can be obtained at the pH in the catalyst deposition step. The coating maintains high adhesion to the insulating substrate, and the swellable resin coating can be easily peeled off at the pH in the coating peeling step.

  More specifically, for example, the catalyst deposition step includes a step of treating in an acidic catalyst metal colloid solution having a pH in the range of 1 to 3, for example, and the film peeling step is in an alkaline solution having a pH in the range of 12 to 14. When the step of swelling the swellable resin film is provided, the swellable resin film has a swelling degree with respect to the acidic catalyst metal colloid solution of 25% or less, further 10% or less, and a swelling degree with respect to the alkaline solution. It is preferable that the resin film has a thickness of 50% or more, more preferably 100% or more, and even more preferably 500% or more.

  Examples of such a swellable resin film include photocuring used for a sheet formed from an elastomer having a predetermined amount of carboxyl groups, a dry film resist (hereinafter also referred to as DFR) for patterning printed wiring boards, and the like. And a sheet obtained by curing the entire surface of a curable alkali-developing resist, and thermosetting or alkali-developing sheet.

  Specific examples of the elastomer having a carboxyl group include a diene elastomer such as a styrene-butadiene copolymer having a carboxyl group in the molecule by containing a monomer unit having a carboxyl group as a copolymerization component; acrylic acid Examples include acrylic elastomers such as ester copolymers; and polyester elastomers. According to such an elastomer, a swellable resin film having a desired alkali swelling degree can be formed by adjusting the acid equivalent, the degree of crosslinking or the degree of gelation of the elastomer dispersed as a suspension or emulsion. . The carboxyl group in the elastomer swells the swellable resin film with respect to the alkaline aqueous solution and acts to peel the swellable resin film from the surface of the insulating substrate. The acid equivalent is the polymer weight per equivalent of carboxyl groups.

  Specific examples of the monomer unit having a carboxyl group include (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, and the like.

  The content ratio of the carboxyl group in the elastomer having such a carboxyl group is preferably 100 to 2000, more preferably 100 to 800 in terms of acid equivalent. When the acid equivalent is too small, the compatibility with the solvent or other composition tends to decrease, whereby the resistance to the plating pretreatment liquid tends to decrease. Moreover, when an acid equivalent is too small, there exists a tendency for the peelability with respect to aqueous alkali solution to fall.

  The molecular weight of the elastomer is preferably 10,000 to 1,000,000, more preferably 20,000 to 60,000. When the molecular weight of the elastomer is too large, the releasability tends to decrease, and when it is too small, the viscosity decreases, so that it is difficult to maintain a uniform thickness of the swellable resin film, and plating pretreatment The resistance to the liquid also tends to deteriorate.

  In addition, as DFR, a photocurable resin containing a photopolymerization initiator containing a predetermined amount of a carboxyl group, an acrylic resin; an epoxy resin; a styrene resin; a phenol resin; A sheet of a resin composition can be used. As specific examples of such DFR, a dry film of a photopolymerizable resin composition as disclosed in JP 2000-231190 A, JP 2001-201851 A, and JP 11-212262 A is used. Sheets obtained by curing, and commercially available as an alkali development type DFR, for example, UFG series manufactured by Asahi Kasei Corporation can be mentioned.

  Furthermore, as another example of the swellable resin film, a resin containing a carboxyl group and containing rosin as a main component (for example, “NAZDAR229” manufactured by Yoshikawa Chemical Co., Ltd.) or a resin containing phenol as a main component (for example, LEKTRACHEM “104F”) and the like.

A swellable resin film is formed on a surface of an insulating substrate by applying a resin suspension or emulsion on the surface of the insulating substrate using a conventionally known application method such as a spin coat method or a bar coater method, and then drying it. The bonded DFR can be easily formed by pasting the DFR on the surface of the insulating substrate using a vacuum laminator or the like and then curing the entire surface.

  Further, the width of the circuit groove formed in the circuit groove forming step is not particularly limited. Specifically, for example, the circuit groove preferably includes a portion having a line width of at least 5 to 30 μm. The circuit groove 3 defines a portion where a plating layer is formed by electroless plating, that is, a portion where an electric circuit is formed. Specifically, for example, the width of the circuit groove formed here is the line width of the electric circuit formed in the present embodiment. That is, in the case of such an electric circuit with a narrow line width, a circuit board having a sufficiently high density circuit can be obtained. In the case of such an electric circuit having a narrow line width, generally, the contact area between the electric circuit and the insulating substrate is narrow, the adhesion between the electric circuit and the insulating substrate is lowered, and the electric circuit is insulated from the insulating substrate. Easy to peel from the material. By adopting the above configuration, even in the case of an electric circuit with a narrow line width as described above, the adhesion between the electric circuit and the insulating base is sufficiently high, and the electric circuit from the insulating base is A circuit board capable of suppressing peeling is obtained.

  Note that the depth of the circuit groove is the depth of the electric circuit formed in this embodiment when a step is eliminated between the electric circuit and the insulating base material by fill-up plating. In addition, when laser processing is used, a fine circuit having a line width of 20 μm or less can be easily formed.

  The plating catalyst 5 is a catalyst that is applied to form a plating layer only on a portion where it is desired to form a plating layer by electroless plating in the plating treatment step. Any plating catalyst can be used without particular limitation as long as it is known as a catalyst for electroless plating. Alternatively, a plating catalyst precursor may be deposited in advance, and the plating catalyst may be generated after the resin film is peeled off. Specific examples of the plating catalyst include, for example, metal palladium (Pd), platinum (Pt), silver (Ag), etc., or a precursor that generates these.

  Examples of the method for depositing the plating catalyst 5 include a method of treating with an acidic Pd—Sn colloid solution treated under acidic conditions of pH 1 to 3, and then treating with an acid solution. Specific examples include the following methods.

First, oil or the like adhering to the surface of the insulating base material 1 in which the circuit grooves 3 and the through holes 4 are formed is washed in hot water in a surfactant solution (cleaner / conditioner) for a predetermined time. Next, if necessary, a soft etching treatment is performed with a sodium persulfate-sulfuric acid based soft etching agent. And it pickles further in acidic solutions, such as sulfuric acid aqueous solution of pH 1-2, and aqueous hydrochloric acid. Next, a pre-dip treatment is performed in which a chloride ion is adsorbed on the surface of the insulating base material 1 by being immersed in a pre-dip solution mainly composed of a stannous chloride aqueous solution having a concentration of about 0.1%. Thereafter, Pd and Sn are aggregated and adsorbed by further dipping in an acidic catalytic metal colloid solution such as acidic Pd—Sn colloid having pH 1 to 3 containing stannous chloride and palladium chloride. Then, an oxidation-reduction reaction (SnCl ₂ + PdCl ₂ → SnCl ₄ + Pd ↓) is caused between the adsorbed stannous chloride and palladium chloride. Thereby, the metal palladium which is a plating catalyst precipitates.

  In addition, as an acidic catalyst metal colloid solution, a well-known acidic Pd-Sn colloid catalyst solution etc. can be used, You may use the commercial plating process using an acidic catalyst metal colloid solution. Such a process is systematized and sold by Rohm & Haas Electronic Materials Co., Ltd., for example.

  As a method for removing the resin film 2, a method in which the resin film 2 is dissolved or removed by swelling by immersing the insulating base material 1 coated with the resin film 2 in a liquid such as an alkaline solution for a predetermined time. Is mentioned. As the alkaline solution, for example, an aqueous sodium hydroxide solution having a concentration of about 1 to 10% can be used. Moreover, you may improve removal efficiency by irradiating an ultrasonic wave during immersion. In addition, when it swells and peels, you may peel off with a light force.

  The case where the swellable resin film is used as the resin film 2 will be described.

  As the liquid (swelling liquid) for swelling the swellable resin film 2, the swellable resin film 2 can be easily obtained without substantially decomposing or dissolving the insulating substrate 1, the swellable resin film 2 and the plating catalyst 5. Any liquid that can be swollen to such an extent that it can be peeled can be used without particular limitation. Such a swelling liquid can be appropriately selected depending on the type and thickness of the swellable resin film 2. Specifically, for example, when the swellable resin film is formed of an elastomer such as a diene elastomer, an acrylic elastomer, and a polyester elastomer, for example, sodium hydroxide having a concentration of about 1 to 10% An aqueous alkali solution such as an aqueous solution can be preferably used.

  In the case of using a plating process that is performed under acidic conditions as described above in the catalyst deposition step, the swelling resin film 2 has a swelling degree of 10% or less under acidic conditions, and under alkaline conditions. It is preferably formed from an elastomer such as a diene elastomer, an acrylic elastomer, and a polyester elastomer having a degree of swelling of 50% or more. Such a swellable resin film easily swells and peels off with an alkaline aqueous solution having a pH of 12 to 14, for example, a sodium hydroxide aqueous solution having a concentration of about 1 to 10%. In addition, in order to improve peelability, you may irradiate with an ultrasonic wave during immersion. Moreover, you may peel by peeling with a light force as needed.

  Examples of the method for swelling the swellable resin film 2 include a method of immersing the insulating base material 1 coated with the swellable resin film 2 in a swelling liquid for a predetermined time. Moreover, in order to improve peelability, it is particularly preferable to irradiate with ultrasonic waves during immersion. In addition, when not peeling only by swelling, you may peel off with a light force as needed.

  As a method of the electroless plating treatment, the insulating substrate 1 partially coated with the plating catalyst 5 is immersed in an electroless plating solution, and only the portion where the plating catalyst 5 is deposited is electroless plated film. A method of depositing (plating layer) may be used.

  Examples of the metal used for electroless plating include copper (Cu), nickel (Ni), cobalt (Co), and aluminum (Al). In these, the plating which has Cu as a main component is preferable from the point which is excellent in electroconductivity. Moreover, when Ni is included, it is preferable from the point which is excellent in corrosion resistance and adhesiveness with a solder.

  The film thickness of the electroless plating film 6 is not particularly limited. Specifically, for example, it is preferably about 0.1 to 10 μm, more preferably about 1 to 5 μm. In particular, by increasing the depth of the circuit groove 3, it is possible to easily form a metal wiring having a large thickness and a large cross-sectional area. In this case, it is preferable because the strength of the metal wiring can be improved.

  Through the plating process, an electroless plating film is deposited only on the portion of the surface of the insulating base 1 where the plating catalyst 5 remains. Therefore, it is possible to accurately form the conductive layer only in the portion where the circuit groove is to be formed. On the other hand, the deposition of the electroless plating film on the portion where the circuit groove is not formed can be suppressed. Therefore, even when a plurality of fine circuits having a narrow line width with a narrow pitch interval are formed, an unnecessary plating film does not remain between adjacent circuits. Therefore, the occurrence of a short circuit and the occurrence of migration can be suppressed.

(Second Embodiment)
In the first embodiment, the circuit board obtained by forming an electric circuit on a flat insulating base material has been described, but the present invention is not particularly limited thereto. Specifically, even when a three-dimensional insulating base material having a stepped three-dimensional surface is used as the insulating base material, a circuit board (stereoscopic circuit board) having an accurate electric circuit of wiring can be obtained.

  Hereinafter, the manufacturing method of the three-dimensional circuit board concerning 2nd Embodiment is demonstrated.

  FIG. 4 is a schematic cross-sectional view for explaining each step of manufacturing the three-dimensional circuit board according to the second embodiment.

  First, as shown in FIG. 4A, the resin coating 2 is formed on the surface of the three-dimensional insulating substrate 51 having a stepped portion. This process corresponds to a film forming process.

  As the three-dimensional insulating base 51, various resin molded bodies that can be used for manufacturing a three-dimensional circuit board known in the art can be used without any particular limitation. It is preferable from the viewpoint of production efficiency that such a molded body is obtained by injection molding. Specific examples of the resin material for obtaining the resin molding include polycarbonate resin, polyamide resin, various polyester resins, polyimide resin, polyphenylene sulfide resin, and the like.

  The method for forming the resin coating 2 is not particularly limited. Specifically, for example, the same formation method as in the first embodiment can be used.

  Next, as shown in FIG. 4 (B), a desired shape and depth are obtained by laser processing or machining the three-dimensional insulating substrate 51 on which the resin coating 2 is formed from the outer surface side of the resin coating 2. The circuit groove 3 is formed. The laser processing or machining for forming the circuit groove 3 is performed by cutting beyond the thickness of the resin coating 2 on the basis of the outer surface of the resin coating 2. This step corresponds to a circuit groove forming step.

  The circuit groove 3 defines a portion where a plating layer is formed by electroless plating, that is, a portion where an electric circuit is formed.

  Next, as shown in FIG. 4C, a catalytic metal (plating catalyst) 5 is deposited on the surface of the circuit groove 3 and the surface of the resin film 2 where the circuit groove 3 is not formed. This step corresponds to a catalyst deposition step. By such a catalyst deposition process, the catalyst metal 5 can be deposited on the surface of the circuit groove 3 and the surface of the resin coating 2 as shown in FIG.

  Next, as shown in FIG. 4D, the resin coating 2 is peeled from the three-dimensional insulating substrate 51. By doing so, the catalyst metal 5 can remain only on the surface of the portion of the three-dimensional insulating base 51 where the circuit groove 3 is formed. On the other hand, the catalytic metal 5 deposited on the surface of the resin film 2 is removed together with the resin film 2 while being supported on the resin film 2. This process corresponds to a film peeling process.

  Next, as shown in FIG. 4 (E), electroless plating is applied to the three-dimensional insulating substrate 51 from which the resin film 2 has been peeled off. By doing so, the plating layer 6 is formed only in the portion where the catalyst metal 5 remains. That is, the plating layer 6 which becomes an electric circuit is formed in the portion where the circuit groove 3 and the through hole 4 are formed. This process corresponds to a plating process.

  Through the above steps, a circuit board 60 in which the electric circuit 6 is formed on the three-dimensional solid insulating base 51 as shown in FIG. 4E is formed. The circuit board 60 formed in this way has high adhesion between the insulating substrate and the electric circuit even if the line width and the line interval of the electric circuit formed on the insulating substrate are narrow, and the electric circuit is damaged. Hateful. The circuit board according to the present embodiment is also accurately and easily formed on the surface of the three-dimensional circuit board having the stepped portion.

  Hereinafter, the manufacturing method of the present embodiment will be described more specifically with reference to examples. The scope of the present invention is not construed as being limited in any way by the following examples.

Example 1
First, silica particles having an average particle diameter of 0.5 μm (SO-C2 manufactured by Admatechs Co., Ltd.), bisphenol A type epoxy resin (850S manufactured by DIC Corporation), and dicyandiamide ( The base material which consists of Nippon Carbide Industries Co., Ltd. product DICY) was prepared. In addition, the said insulating base material was 30 mass% with respect to the said insulating base material, and the thickness of the said silica particle was a base material of 100 micrometers.

  Next, a 2 μm-thick styrene-butadiene copolymer (SBR) coating (resin coating) was formed on the surface of the insulating substrate. The coating was formed on the main surface of the insulating base material by methyl ethyl ketone (MEK) suspension (manufactured by Nippon Zeon Co., Ltd., acid equivalent 600, particle diameter 200 nm, solid content 15) of styrene-butadiene copolymer (SBR). %) Was applied and dried at 80 ° C. for 30 minutes.

  Then, a circuit groove having a substantially rectangular cross section having a width of 20 μm, a depth of 20 μm, and a length of 30 mm was formed on the insulating base material on which the resin coating was formed by laser processing. For laser processing, a laser beam irradiation device (MODEL 5330 manufactured by ESI) equipped with a UV-YAG laser was used.

  Next, the insulating base material on which the circuit grooves were formed was immersed in a cleaner conditioner (surfactant solution, pH <1: C / N 3320 manufactured by Rohm and Haas Electronic Materials Co., Ltd.), and then washed with water. . Then, soft etching treatment was performed with a sodium persulfate-sulfuric acid-based soft etchant having a pH <1. Then, a pre-dip process was performed using PD404 (manufactured by Shipley Far East Co., Ltd., pH <1). And palladium which becomes the nucleus (catalyst metal) of electroless copper plating by being immersed in the acidic Pd-Sn colloidal solution (CAT44, Shipley Far East Co., Ltd.) of pH 1 containing stannous chloride and palladium chloride. Was adsorbed on an insulating substrate in the form of a tin-palladium colloid.

  Next, palladium nuclei were generated by immersing in an accelerator chemical solution (ACC19E, manufactured by Shipley Far East Co., Ltd.) having a pH <1. Then, the insulating substrate was immersed for 10 minutes in a 5% aqueous sodium hydroxide solution of pH 14 while being subjected to ultrasonic treatment. As a result, the SBR coating on the surface swelled and peeled cleanly. At this time, no SBR coating fragments remained on the surface of the insulating base. Then, the insulating substrate was immersed in an electroless plating solution (CM328A, CM328L, CM328C, manufactured by Shipley Far East Co., Ltd.) to perform an electroless copper plating process.

A plating layer having a thickness of 5 μm was formed on the circuit groove by the electroless copper plating treatment. Furthermore, electroless copper plating treatment (fill-up plating) was performed until the circuit groove was filled. The swelling degree of the swellable resin film was determined as follows.

  The SBR suspension applied to form a swellable resin film on the release paper was applied and dried at 80 ° C. for 30 minutes. Thereby, a 2 μm thick resin film was formed. And the sample was obtained by forcibly peeling the formed film.

  And about 0.02 g of the obtained sample was weighed. The weight of the sample at this time is defined as the weight m (b) before swelling. The weighed sample was immersed in 10 ml of 5% aqueous sodium hydroxide solution at 20 ± 2 ° C. for 15 minutes. Similarly, another sample was immersed in 10 ml of a 5% aqueous hydrochloric acid solution (pH 1) at 20 ± 2 ° C. for 15 minutes.

  Then, centrifugation was performed at 1000 G for about 10 minutes using a centrifuge to remove moisture and the like attached to the sample. Then, the weight of the swollen sample after centrifugation was measured and set as the weight m (a) after swelling. From the obtained weight m (b) before swelling and weight m (a) after swelling, the formula “swelling degree SW = (m (a) −m (b)) / m (b) × 100 (%)” From this, the degree of swelling was calculated. Other conditions were performed in accordance with JIS L1015 8.27 (measurement method of alkali swelling degree).

  At this time, the degree of swelling with respect to a sodium hydroxide 5% aqueous solution at pH 14 was 750%. On the other hand, the degree of swelling with respect to a 5% hydrochloric acid aqueous solution at pH 1 was 3%.

(Example 2)
It is the same as Example 1 except having replaced the content of the said silica particle with the insulating base material of 50 mass% from the insulating base material of 30 mass%.

(Example 3)
Example 1 is the same as Example 1 except that the insulating base material containing silica particles having an average particle diameter of 0.5 μm is replaced with the insulating base material containing silica particles having an average particle diameter of 1.5 μm.

Example 4
Silica particles having an average particle diameter of 0.5 μm and containing 30 mass% of insulating base material, silica particles having an average particle diameter of 1.5 μm and containing 50 mass% of insulation Example 1 is the same as Example 1 except that the base material is replaced.

(Example 5)
Insulating silica particles having an average particle diameter of 0.5 μm, containing silica particles having an average particle diameter of 1.7 μm from an insulating base material having a content of 30% by mass, and having an insulating content of 75% by mass Example 1 is the same as Example 1 except that the base material is replaced.

(Example 6)
Example 1 is the same as Example 1 except that the insulating base material containing silica particles having an average particle diameter of 0.5 μm is replaced with the insulating base material containing silica particles having an average particle diameter of 0.05 μm.

(Example 7)
Insulating silica particles having an average particle diameter of 0.5 μm and containing silica particles having an average particle diameter of 0.05 μm from an insulating base material having a content of 30% by mass and an insulating content of 50% by mass. Example 1 is the same as Example 1 except that the base material is replaced.

(Comparative example)
As an insulating base material, an insulating base material [a base material made of bisphenol A type epoxy resin (850S manufactured by DIC Corporation) and dicyandiamide (DICY manufactured by Nippon Carbide Industries Co., Ltd.) as a curing agent] is used. It is the same as that of Example 1 except using.

  The said Examples 1-7 and the comparative example were evaluated as follows.

(Circuit groove shape)
First, the insulating base material after forming the circuit groove in a direction perpendicular to the direction in which the circuit groove extends,
7 places were cut. The cut surface was observed using a microscope (KH-7700 manufactured by Hilox Co., Ltd.). And it evaluated with the following evaluation criteria.

A: There was no place where resin elution was confirmed (0 places).
○: The location where resin elution was confirmed was 1 in 7 locations. Δ: The location where resin elution was confirmed was 2 locations in 7 locations. X: Elution of resin was confirmed. There were 3 or more locations in 7 locations.

(Not plated)
Before performing the fill-up plating on the plating layer formed on the circuit groove (width 20 μm, length 30 mm) of the insulating substrate by the electroless plating, a microscope (KH-7700 manufactured by Hilox Co., Ltd.) is used. Was used to observe the entire formed plating layer. And it evaluated with the following evaluation criteria.

A: There was no place where it was confirmed that the plating layer was not formed (it was 0 place).
○: The place where it was confirmed that the plating layer was not formed was one place. Δ: The place where it was confirmed that the plating layer was not formed was two places. ×: The plating layer was formed. There were three or more confirmed locations.

(Plating peeling)
Before performing fill-up plating on the plating layer formed on the circuit groove (width 20 μm, length 30 mm) of the insulating substrate by the electroless plating, a microscope (KH-7700 manufactured by Hilox Co., Ltd.) is used. Using, the whole plating layer formed was observed. And it evaluated with the following evaluation criteria.

A: There was no place where it was confirmed that the plating layer was peeled off (it was 0 place).
○: The place where it was confirmed that the plating layer was peeled was one place. Δ: The place where it was confirmed that the plating layer was peeled was two places. ×: The plating layer was peeled off. It was confirmed that there were three or more locations.

  The evaluation results are shown in Table 1.

  As can be seen from Table 1, when the insulating base material containing silica particles as the filler was used (Examples 1 to 7), the circuit groove was compared with the case where the insulating base material not containing the filler was used. When forming, elution of the resin generated in the circuit groove was suppressed. Furthermore, compared with the comparative example, Examples 1-7 had plating non-adherence and plating peeling suppressed. From these, it was found that according to Examples 1 to 7, a circuit board having high adhesion between the electric circuit and the insulating base material can be obtained.

DESCRIPTION OF SYMBOLS 1,21 Insulation base material 2,22 Resin film 3,23 Circuit groove 4 Through-hole 5 Catalytic metal 6 Plating layer (electric circuit)
7 Plating Layer 10 Circuit Board 11 Filler 51 Three-Dimensional Insulating Base Material 60 Circuit Board

Claims (1)

A film forming step of forming a resin film on the surface of the insulating substrate;
A circuit groove forming step of forming a circuit groove of a desired shape and depth by laser processing or machining the insulating base material from the outer surface side of the resin coating;
A catalyst deposition step of depositing a catalyst metal on the surface of the circuit groove and the surface of the resin coating;
A film peeling step for peeling the resin film from the insulating substrate;
A plating process step of performing electroless plating on the insulating base material from which the resin film has been peeled off,
The film forming step uses a material containing inorganic fine particles as a filler as the insulating base material,
The average particle diameter of the filler is 0.5 to 50 with respect to the minimum value among the width of the circuit groove, the depth of the circuit groove, and the width of the portion between adjacent circuit grooves. %
Content of the said filler is 10-90 mass% with respect to the said insulating base material, The manufacturing method of the circuit board characterized by the above-mentioned.

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