JP5465512B2 - Circuit board manufacturing method - Google Patents

Description

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

  In the electronic devices such as portable information terminal devices such as mobile phones; computers and peripheral devices; 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 density of electric circuits, a method of accurately forming wiring of an electric circuit having a narrower line width and line interval (width of a portion between adjacent electric circuits) Is required. In high-density circuit wiring, short-circuiting or migration between wirings is likely to occur. Further, as the number of stacked layers increases, the unevenness generated on the circuit formation surface increases, making it difficult to form fine circuits.

  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) the metal foil other than the portion (circuit forming portion) where the electric circuit on the surface of the metal foil-clad laminate is to be formed. On the other hand, the additive method is a method of forming a predetermined circuit by performing electroless plating only on a portion where a circuit on an insulating substrate is formed.

  The subtractive method is a method in which a thick metal foil is etched to leave only a portion where the electric circuit is to be formed (circuit formation portion), 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, the additive method can form a metal wiring by electroless plating only on 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.

  This invention is made | formed in view of this situation, Comprising: It aims at providing the circuit board by which the highly accurate electric circuit was formed on the insulating base material. It is another object of the present invention to provide a circuit board manufacturing method capable of easily forming a highly accurate electric circuit on an insulating substrate.

  A circuit board according to an aspect of the present invention forms a resin film on a surface, and forms a recess having a depth exceeding the thickness of the resin film on the basis of the outer surface of the resin film. An insulating base material formed by forming a circuit groove having a depth, depositing a plating catalyst or a precursor thereof on the surface of the circuit groove and the surface of the resin film, and peeling the resin film; An electroless plating film formed on the circuit groove by performing electroless plating on the substrate, and the thickness of the electroless plating film is 0.5 or less with respect to the depth of the circuit groove It is characterized by being.

  According to the above configuration, after forming the resin film, a circuit groove having a predetermined pattern is formed by using laser processing or the like, and the portion where the plating film is not formed is protected by the resin film. The plating catalyst or its precursor is deposited on the surface and the surface of the resin coating, and then the resin coating is removed, leaving the plating catalyst or its precursor only in the portion where the plating film is to be formed. From the portion, an insulating substrate from which the plating catalyst or its precursor has been removed is obtained. By electroless plating on the insulating substrate, the plating catalyst or a precursor thereof is a portion where the plating film is to be formed, that is, an electroless plating film formed only on the circuit groove. An electric circuit is obtained.

  Therefore, a circuit board having a highly accurate electric circuit formed on the insulating base material can be obtained. That is, a circuit board in which the outline of the formed circuit is maintained with high accuracy can be obtained. As a result, for example, even when a plurality of circuits are formed at regular intervals, it is possible to suppress the remaining pieces of the electroless plating film between the circuits, and thus suppress the occurrence of short circuits and migration. . In addition, a circuit having a desired depth can be formed.

  In addition, since the thickness of the electroless plating film is smaller than the depth of the circuit groove as described above, the electroless plating film does not easily form a protrusion protruding from the circuit forming surface, and the number of stacked layers Even if this increases, the unevenness generated on the circuit formation surface is small, and a fine circuit can be easily formed.

  Therefore, also from this point, a circuit board having a highly accurate electric circuit formed on the insulating base material can be obtained.

  Moreover, it is preferable that the thickness of the said plating film is 0.25 or more with respect to the depth of the said circuit groove. According to this configuration, it is possible to obtain a circuit board in which a more accurate electric circuit is formed on the insulating base material while suppressing the occurrence of defects.

  Moreover, it is preferable that the thickness of the said plating film is 0.1-10 micrometers. According to this configuration, a circuit board on which a highly accurate electric circuit is formed on the insulating base material can be obtained.

  Moreover, it is preferable that the depth of the said circuit groove is 1-5 micrometers. According to this configuration, a circuit board on which a highly accurate electric circuit is formed on the insulating base material can be obtained.

  The circuit board manufacturing method according to an aspect of the present invention includes a film forming step of forming a resin film on the surface of an insulating base, and a depth exceeding the thickness of the resin film on the basis of the outer surface of the resin film. A circuit groove forming step of forming a circuit groove having a desired shape and depth on the insulating base, and forming a plating catalyst or a precursor thereof on the surface of the circuit groove and the surface of the resin film. A catalyst deposition step for depositing, a coating removal step for removing the resin coating from the insulating substrate, and electroless plating on the insulating substrate from which the resin coating has been removed to form an electroless plating film A plating treatment step, wherein in the plating treatment step, the electroless plating film is formed such that the thickness of the electroless plating film is 0.5 or less with respect to the depth of the circuit groove. And

  According to such a manufacturing method, after forming a resin film on an insulating base material, a circuit groove having a predetermined pattern is formed using laser processing or the like, and a portion where a plating film is not formed is protected by the resin film. In this state, a plating catalyst or a precursor thereof is deposited on the surface of the circuit groove and the surface of the resin film. Thereafter, by removing the resin film from the insulating substrate, the plating catalyst or its precursor is easily left only in the portion where the plating film is to be formed, and the plating catalyst or its precursor is removed from other portions. Can be removed. Therefore, by performing a plating treatment step for forming an electroless plating film, an electroless plating film having a predetermined thickness can be easily formed only on a portion where the plating catalyst or its precursor remains, which is a portion where the plating film is to be formed. Can be formed.

  Therefore, a highly accurate electric circuit can be easily formed on the insulating substrate. That is, the outline of the formed circuit can be maintained with high accuracy. As a result, for example, even when a plurality of circuits are formed at regular intervals, it is possible to suppress the remaining pieces of the electroless plating film between the circuits, and thus suppress the occurrence of short circuits and migration. . In addition, a circuit having a desired depth can be formed.

  In addition, since the thickness of the electroless plating film is smaller than the depth of the circuit groove as described above, the electroless plating film does not easily form a protrusion protruding from the circuit forming surface, and the number of stacked layers Even if this increases, the unevenness generated on the circuit formation surface is small, and a fine circuit can be easily formed.

  In the plating process, it is preferable to form the electroless plating film so that the thickness of the electroless plating film is 0.25 or more with respect to the depth of the circuit groove. According to this configuration, it is possible to easily form a more accurate electric circuit on the insulating base material while suppressing the occurrence of defects.

  Further, the step of removing the resin film from the insulating substrate after the film removal step swells the resin film with a predetermined liquid or dissolves a part of the resin film with a predetermined liquid. It is preferable that According to such a manufacturing method, the resin film can be easily peeled from the insulating base material. Therefore, a highly accurate electric circuit can be more easily formed on the insulating substrate.

  Moreover, it is preferable that the swelling degree with respect to the said liquid of the said resin film is 50% or more. By using a resin film having such a swelling degree, the resin film can be easily peeled from the insulating substrate. Therefore, a highly accurate electric circuit can be more easily formed on the insulating substrate. In addition, the said resin film has a large degree of swelling with respect to the said liquid, and what melt | dissolves with respect to the said liquid is also contained.

  Further, the catalyst deposition step includes a step of treating in an acidic catalyst metal colloid solution, the predetermined liquid in the coating removal step is an alkaline solution, and the resin coating swells with respect to the acidic catalyst metal colloid solution. The degree is preferably less than 50%, and the degree of swelling with respect to the alkaline solution is preferably 50% or more.

  According to such a manufacturing method, the resin film is hardly peeled off in the catalyst deposition process treated under acidic conditions, and is easily peeled off in the film removal process treated with an alkaline solution after the catalyst deposition process. Therefore, the resin coating is selectively peeled off in the coating removal step. Accordingly, the portion where the electroless plating film is not formed can be accurately protected in the catalyst deposition step, and the resin coating can be easily peeled off in the coating removal step after deposition of the plating catalyst or its precursor. For this reason, more accurate circuit formation becomes possible.

  Moreover, it is preferable that the said film removal process is a process of dissolving and removing the said resin film with a predetermined | prescribed liquid. According to such a manufacturing method, the resin film can be easily removed from the insulating base material. Therefore, a highly accurate electric circuit can be more easily formed on the insulating substrate.

  Moreover, it is preferable that the said resin film is a resin film formed by apply | coating an elastomer suspension or emulsion to the said insulating base material surface, and drying. If such a resin film is used, the resin film can be easily formed on the surface of the insulating substrate. Therefore, a highly accurate electric circuit can be more easily formed on the insulating substrate.

  Moreover, it is preferable that the said resin film is a resin film formed by transcribe | transferring the resin film formed on the support substrate to the said insulating base material surface. The resin film used for this transfer is more preferably a resin film formed by applying an elastomer suspension or emulsion to the surface of the support substrate and then drying. If such a resin film is used, a large number of resin films can be prepared in advance, which is preferable from the viewpoint of excellent mass productivity.

  The elastomer is preferably selected from the group consisting of a diene elastomer, an acrylic elastomer, and a polyester elastomer having a carboxyl group. The diene elastomer is more preferably a styrene-butadiene copolymer. According to such an elastomer, it is possible to easily form a resin film having a desired degree of swelling by adjusting the degree of crosslinking or the degree of gelation. In addition, the degree of swelling of the liquid used in the film removal step can be increased, and a resin film that dissolves in the liquid can be easily formed.

  Moreover, as the resin film, a film mainly composed of a resin composed of an acrylic resin having a carboxyl group with an acid equivalent of 100 to 800 is also preferably used.

  In addition, as the resin film, (a) at least one monomer of carboxylic acid or acid anhydride having at least one polymerizable unsaturated group in the molecule, and (b) the (a) single monomer It is preferable to consist of a polymer resin obtained by polymerizing at least one kind of monomer that can be polymerized with a polymer or a resin composition containing the polymer resin. If such a resin film is used, the resin film can be easily formed on the surface of the insulating substrate. Therefore, a highly accurate electric circuit can be more easily formed on the insulating substrate. In addition, many of these resin films can be dissolved by the liquid used in the film removal step, and not only peeling and removal but also dissolution and removal can be used effectively.

  Moreover, it is preferable that the acid equivalent of the said polymer resin is 100-800 in the said resin film.

  The thickness of the resin coating is preferably 10 μm or less from the viewpoint that a fine circuit can be formed with high accuracy.

  In addition, it is preferable that the circuit groove has a width of 20 μm or less because an antenna circuit or the like that requires fine processing can be formed.

  Further, when the circuit groove forming step is a step of forming a circuit groove by laser processing, it is preferable because a finer circuit can be formed with high accuracy. Further, it is preferable in that the cutting depth and the like can be easily adjusted by changing the laser output and the like, and thus the depth of the formed circuit groove can be easily adjusted. Further, by using laser processing, a through hole used for interlayer connection can be formed, or a capacitor can be embedded in an insulating base material.

  Further, when the circuit groove forming step is a step of forming a circuit groove using a mold pressing method, it is preferable because the circuit groove can be easily formed by stamping a mold.

  In the circuit groove forming step, it is preferable that a through hole is formed in the insulating base material when the circuit groove is formed. According to such a manufacturing method, it is possible to form a through hole that can be used for a via hole or an inner via hole when forming a circuit groove. A via hole or an inner via hole is formed by electroless plating the formed through hole.

  Moreover, it is also a preferable embodiment that the insulating base material has a step surface formed in a step shape, and the surface of the insulating base material is the step surface. That is, the insulating base material has a step surface formed in a step shape, and the coating film forming step, the circuit groove forming step, the catalyst deposition step, the coating film removing step, and the plating treatment are formed on the step surface. It is also a preferable form to perform the process. According to such a manufacturing method, a circuit that can overcome a step can be easily formed.

  Moreover, it is preferable that the said resin film contains a fluorescent substance, and after the said film removal process, it further has the test process for test | inspecting a film removal defect using the light emission from the said fluorescent substance. In the manufacturing method as described above, when the line width and the line interval become extremely narrow, the resin film that should originally be removed is completely removed between adjacent circuit grooves. There is also concern that it will remain slightly. Further, there is a concern that the resin film fragments removed during the formation of the circuit groove may enter and remain in the formed circuit groove. When the resin film remains between the circuit grooves, an electroless plating film is formed at the portion, which may cause migration or short circuit. In addition, if a resin film fragment remains in the formed circuit groove, it may cause poor heat resistance and propagation loss of the electric circuit. In such a case, the resin film is made to contain a fluorescent substance as described above, and after the film removal step, only a portion where the resin film remains by irradiating a predetermined light source on the surface from which the film has been removed. By emitting light with the fluorescent substance, it is possible to inspect the presence or absence of the film removal failure or the location of the film removal failure.

  A circuit board according to another embodiment of the present invention is obtained by the method for manufacturing a circuit board. According to such a configuration, a circuit board on which a highly accurate electric circuit is formed on the insulating base material can be obtained.

  According to the present invention, an object is to provide a circuit board in which a highly accurate electric circuit is formed on an insulating base material. Further, it is possible to provide a circuit board manufacturing method capable of easily forming a highly accurate electric circuit on an insulating substrate. That is, the outline of the electric circuit formed by the electroless plating film can be maintained with high accuracy. Thereby, it can suppress that the fragment | piece etc. of an unnecessary electroless plating film | membrane remain in parts other than a circuit formation part, and, thereby, generation | occurrence | production of a short circuit, migration, etc. can be suppressed.

It is a schematic cross section for explaining each process in a manufacturing method of a circuit board concerning a 1st embodiment. In 1st Embodiment, it is drawing for demonstrating the state of the insulation base material 1 after the said circuit groove formation process and the said plating process process. It is explanatory drawing for demonstrating the test | inspection process for making a resin film contain a fluorescent substance and test | inspecting a film removal defect using the light emission from a fluorescent substance. 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.

[First Embodiment]
The circuit board according to the present embodiment forms a resin film on the surface, and forms a recess having a depth exceeding the thickness of the resin film with reference to the outer surface of the resin film, thereby obtaining a desired shape and depth. An insulating substrate formed by depositing a plating catalyst or a precursor thereof on the surface of the circuit groove and the surface of the resin coating, and peeling off the resin coating, and the insulating substrate An electroless plating film is formed on the circuit groove, and the thickness of the electroless plating film is 0.5 or less with respect to the depth of the circuit groove. It is characterized by.

  First, a method for manufacturing a circuit board according to the first embodiment of the present invention will be described. Specifically, the insulating group is formed by forming a resin film on the surface of the insulating substrate, and forming a recess having a depth exceeding the thickness of the resin film with reference to the outer surface of the resin film. A circuit groove forming step for forming a circuit groove having a desired shape and depth in the material, a catalyst deposition step for depositing a plating catalyst or a precursor thereof on the surface of the circuit groove and the surface of the resin film, and the insulation A coating removal step for removing the resin coating from the substrate; and a plating treatment step for forming an electroless plating film by performing electroless plating on the insulating substrate from which the resin coating has been removed. In the manufacturing method, the electroless plating film is formed so that the thickness of the electroless plating film is 0.5 or less with respect to the depth of the circuit groove.

  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 in the circuit board manufacturing method 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.

  Next, as shown in FIG. 1B, a circuit groove 3 having a depth equal to or greater than the thickness of the resin coating 2 is formed with the outer surface of the resin coating 2 as a reference. Moreover, you may drill the hole for forming the through-hole 4 as a part of the said circuit groove 3 in the said insulating base material 1 as needed. The circuit groove 3 defines a portion where an electroless plating film is formed by electroless plating, that is, a portion where an electric circuit is formed. This step corresponds to a circuit groove forming step.

  Next, as shown in FIG. 1C, a plating catalyst or its precursor 5 is deposited on the surface of the circuit groove 3 and the surface of the resin film 2 on which the circuit groove 3 is not formed. This step corresponds to a catalyst deposition step.

  Next, as shown in FIG. 1D, the resin film 2 is removed from the insulating base material 1. By doing so, a plating catalyst or its precursor 5 can be made to remain only on the surface of the insulating substrate 1 where the circuit groove 3 is formed. On the other hand, the plating catalyst or its precursor 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 removal process.

  Next, electroless plating is performed on the insulating substrate 1 from which the resin coating 2 has been removed. By doing so, the electroless plating film 6 is formed only in the portion where the plating catalyst or its precursor 5 remains. That is, as shown in FIG. 1E, an electroless plating film to be an electric circuit 6 is formed in the portion where the circuit groove 3 is formed. And this electric circuit 6 may consist of this electroless-plated film, or the electroless-plated film is further thickened by further electroless plating (fill-up plating). There may be. Specifically, the electroless plating film 6 may be formed so that the thickness of the electroless plating film 6 is 0.5 or less with respect to the depth of the circuit groove 3. That is, the electroless plating film 6 may be formed so that the thickness of the electroless plating film 6 / the depth of the circuit groove 3 is 0.5 or less. The electroless plating film 6 is preferably formed so that the thickness of the electroless plating film 6 is 0.25 or more with respect to the depth of the circuit groove 3. That is, it is preferable to form the electroless plating film 6 so that the thickness of the electroless plating film 6 / the depth of the circuit groove 3 is 0.25 or more. 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 is obtained by forming the electric circuit 6 on the insulating base material 1 with high accuracy.

  In the circuit board manufacturing method as described above, the shape and size of the circuit groove 3 and the electroless plating film (electric circuit) 6 are as follows. FIG. 2 is a drawing for explaining the state of the insulating substrate 1 after the circuit groove forming step and after the plating step. 2A shows after the circuit groove forming step, and FIG. 2B shows after the plating step.

  First, the shape of the circuit groove 3 is not particularly limited. Specifically, for example, the cross section perpendicular to the longitudinal direction of the circuit groove 3 may be a rectangular shape or a U shape as shown in FIG. The U-shape is preferable from the viewpoint that the length of the circumference of the wiring with respect to the cross-sectional area of the wiring (electric circuit) becomes long and propagation loss, particularly propagation loss of a high frequency signal can be reduced.

  Further, the thickness T of the electroless plating film 6 is not particularly limited as long as it satisfies a predetermined relationship with the depth D of the circuit groove 3. Specifically, the thickness is not particularly limited as long as T / D is 0.5 or less. Further, the thickness T of the electroless plating film 6 is preferably such that T / D is 0.25 or more.

  If the thickness T of the electroless plating film 6 is too thin, the electric resistance of the electric circuit (wiring) tends to increase. On the other hand, if the thickness T of the electroless plating film 6 is too thick, the above-described merit that the propagation loss, particularly the propagation loss of a high-frequency signal can be reduced tends to be reduced.

  If the thickness T (T / D) of the electroless plating film 6 with respect to the depth D of the circuit groove 3 is too small, the electrical resistance of the electric circuit (wiring) increases and there is a risk of open failure due to thermal history or the like. There is a tendency to increase. On the other hand, if T / D is too large, the above-described merit that propagation loss, particularly propagation loss of a high-frequency signal can be reduced tends to be reduced.

  Moreover, although the specific thickness T of the said electroless-plating film 6 changes with the depth D of the said circuit groove 3, it is preferable that it is 0.1-10 micrometers, for example.

  The depth D of the circuit groove 3 is not particularly limited as long as the above T / D relationship is satisfied. Specifically, for example, the depth D is preferably 1 to 5 μm.

  Further, the size of the circuit groove 3 and the electroless plating film (electric circuit) 6 is specifically set to the circuit groove when, for example, the specific thickness T of the electroless plating film 6 is 5 μm. 3 may have a depth D of 20 μm or 10 μm. The T / D at this time is 0.25 or 0.5.

  The sizes of the circuit groove 3 and the electroless plating film (electric circuit) 6 can be measured by, for example, observing a cross section perpendicular to the longitudinal direction of the circuit groove 3 with an SEM.

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

<Film formation process>
As described above, the film forming process is a process of forming the resin film 2 on the surface of the insulating substrate 1.

(Insulating base material)
The insulating base material 1 used in the film forming step is not particularly limited as long as it can be used for manufacturing a circuit board. Specifically, for example, a resin substrate containing a resin can be used.

  As the resin substrate, various organic substrates that can be used for manufacturing a circuit board, for example, a multilayer circuit board, can be used without any particular limitation. Specific examples of organic substrates include those conventionally used in the manufacture of multilayer circuit boards, such as epoxy resins, acrylic resins, polycarbonate resins, polyimide resins, polyphenylene sulfide resins, polyphenylene ether resins, cyanate resins, benzoxazine resins, bis Examples include a substrate made of maleimide resin or the like.

  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 a phenolic hydroxyl group, triglycidyl isocyanurate, alicyclic epoxy resins, and the like. Furthermore, the epoxy resin, nitrogen-containing resin, and silicone-containing resin that are brominated or phosphorus-modified to impart flame retardancy are also included. Moreover, as said epoxy resin and resin, said each epoxy resin and 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 cyanate resins. As said phenol type hardening | curing agent, a novolak type, an aralkyl type, a terpene type etc. are mentioned, for example. Further examples include phosphorus-modified phenolic resins or phosphorus-modified cyanate resins for imparting flame retardancy. 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.

  Although not particularly limited, it is preferable to use a resin or the like having a good laser light absorption rate in the wavelength region of 100 to 400 nm because a circuit pattern is formed by laser processing. For example, specifically, a polyimide resin or the like can be given.

  The insulating base material (insulating layer) may contain a filler. The filler may be inorganic fine particles or organic fine particles, and is not particularly limited. By containing the filler, the filler is exposed to the laser processed portion, and it is possible to increase the adhesion between the plating due to the unevenness of the filler and the resin.

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. Although not particularly limited, it is preferable to use a filler having an average particle diameter equal to or smaller than the thickness of the insulating layer, more preferably 0.01 to 10 μm, and still more preferably a filler having an average particle diameter of 0.05 μm to 5 μm. Is good.

  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. The silane coupling agent is not particularly limited. Specific examples include silane coupling agents such as epoxy silane, mercapto silane, amino silane, vinyl silane, styryl silane, methacryloxy silane, acryloxy silane, and titanate. 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. The dispersant is not particularly limited. Specific examples include dispersants such as alkyl ether, sorbitan ester, alkyl polyether amine, and polymer. As said dispersing agent, the said dispersing agent may be used independently, and may be used in combination of 2 or more type.

(Resin coating)
The resin film 2 is not particularly limited as long as it can be removed in the film removal step. Specifically, for example, a soluble resin that can be easily dissolved in an organic solvent or an alkaline solution, a swellable resin film made of a resin that can be swollen with a predetermined liquid (swelling liquid) described later, and the like. Among these, a swellable resin film is particularly preferable because accurate removal is easy. Moreover, as said swelling resin film, it is preferable that the swelling degree with respect to the said liquid (swelling liquid) is 50% or more, for example. The swellable resin film is not limited to the resin film that does not substantially dissolve in the liquid (swelling liquid) and easily peels off from the surface of the insulating substrate 1 due to swelling. A resin film that swells with respect to the swelling liquid), dissolves at least partly and easily peels off from the surface of the insulating substrate 1 due to the swelling or dissolution, or dissolves in the liquid (swelling liquid). Moreover, the resin film which peels from the said insulating base material 1 surface easily by the melt | dissolution is also contained.

  A method for forming the resin coating 2 is not particularly limited. Specifically, for example, it is formed by applying a liquid material capable of forming a resin film on the surface of the insulating base material 1 and then drying it, or by applying the liquid material to a support substrate and then drying it. And a method of transferring the resin film to be transferred onto the surface of the insulating substrate 1. 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. If the thickness of the resin coating 2 is too thick, the accuracy of circuit grooves and through-holes formed by laser processing or machining in the circuit groove forming process 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. Furthermore, a resin film having a swelling degree with respect to the swelling liquid of 100% or more 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 removal process.

  The formation method of the said swellable resin film is not specifically limited, What is necessary is just the method similar to the formation method of the resin film 2 mentioned above. Specifically, for example, a liquid material capable of forming a swellable resin film is applied to the surface of the insulating base material 1 and then dried, or the liquid material is applied to a support substrate and then dried. And a method of transferring the swellable resin film formed by the method to the surface of the insulating substrate 1.

  Examples of the liquid material that can form the swellable resin film include an elastomer suspension or emulsion. 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 removal step, so that the 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 removal step.

  More specifically, for example, the catalyst deposition step includes a step of treating in an acidic plating catalyst colloid solution (acid catalytic metal colloid solution) having a pH in the range of 1-3, for example, and the coating removal step has a pH of 12-12. When the step of swelling the swellable resin film in an alkaline solution in the range of 14 is provided, the swelling degree of the swellable resin film with respect to the acidic plating catalyst colloid solution is less than 50%, and further 40% or less. The resin film preferably has a degree of swelling with respect to the alkaline solution 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 large, 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.

  The resin coating includes (a) at least one monomer of carboxylic acid or acid anhydride having at least one polymerizable unsaturated group in the molecule and (b) the monomer (a). And a polymer resin obtained by polymerizing at least one monomer that can be polymerized with or a resin composition containing the polymer resin.

  As the resin composition, the polymer resin may be an essential component as a main resin, and at least one of oligomers, monomers, fillers, and other additives may be added. The main resin is preferably a linear polymer having thermoplastic properties. In order to control fluidity, crystallinity, etc., it may be grafted and branched. As the molecular weight, it is about 1000-500000 in a weight average molecular weight, and 5000-50000 are preferable. If the molecular weight is too small, the flexibility of the film and the resistance to the plating nucleation solution (acid resistance) tend to decrease. Moreover, when molecular weight is too large, there exists a tendency for the sticking property at the time of using alkali peelability or a dry film to worsen. Furthermore, a cross-linking point may be introduced for improving the resistance to plating nucleus chemicals, suppressing thermal deformation during laser processing, and controlling flow.

  As described above, the composition of the polymer resin as the main resin includes (a) a carboxylic acid or acid anhydride monomer having at least one polymerizable unsaturated group in the molecule, and (b) the above ( a) It is obtained by polymerizing a monomer that can be polymerized with the monomer. Examples of known techniques include those described in JP-A-7-281437, JP-A-2000-231190, and JP-A-2001-201851.

  Examples of (a) include (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, maleic acid half ester, butyl acrylate, etc., alone or in combination of two or more May be combined.

  Examples of (b) are generally non-acidic and have (one) polymerizable unsaturated group in the molecule, but are not limited thereto. It is selected so as to maintain various properties such as resistance in the plating process and flexibility of the cured film. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert. -Butyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylates. Further, there are esters of vinyl alcohol such as vinyl acetate, (meth) acrylonitrile, styrene or polymerizable styrene derivatives. It can also be obtained by polymerization of only a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Furthermore, a monomer having a plurality of unsaturated groups is selected as a monomer used in the polymer so that it can be three-dimensionally cross-linked, such as an epoxy group, a hydroxyl group, an amino group, an amide group, a vinyl group in the molecular skeleton. Reactive functional groups can be introduced. The amount of the carboxyl group contained in the resin is preferably 100 to 2000, preferably 100 to 800, as an acid equivalent. Here, the acid equivalent means the weight of the polymer having 1 equivalent of a carboxyl group therein. When the acid equivalent is too low, there is a tendency that compatibility with a solvent or other composition is lowered or plating pretreatment solution resistance is lowered. Moreover, when an acid equivalent is too high, there exists a tendency for peelability to fall. Moreover, the composition ratio of (a) monomer is 5-70 mass%.

  Any monomer or oligomer may be used as long as it is resistant to plating nucleation chemicals and can be easily removed with alkali. Further, in order to improve the sticking property of the dry film (DFR), it can be considered that it is used as a tackifier as a plasticizer. Further, a crosslinking agent is added to increase various resistances. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert. -Butyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylates. Further, there are esters of vinyl alcohol such as vinyl acetate, (meth) acrylonitrile, styrene or polymerizable styrene derivatives. It can also be obtained by polymerization of only a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Furthermore, a polyfunctional unsaturated compound may be included. Any of the above monomers or oligomers obtained by reacting the monomers may be used. In addition to the above monomers, it is possible to include two or more other photopolymerizable monomers. Examples of monomers include 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polyoxyethylene Polyoxyalkylene glycol di (meth) acrylate such as polyoxypropylene glycol di (meth) acrylate, 2-di (p-hydroxyphenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, dipentaerythritol penta (meth) Acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether tri (meth) acrylate, 2,2-bis (4-methacryloxy) Pointer ethoxyphenyl) propane, there is a polyfunctional (meth) acrylate containing urethane groups. Any of the above monomers or oligomers obtained by reacting the monomers may be used.

  Furthermore, you may contain a filler. The filler is not particularly limited, but silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, clay, kaolin, titanium oxide, barium sulfate, alumina, zinc oxide, talc, mica, glass, potassium titanate, wollastonite, sulfuric acid Magnesium, aluminum borate, an organic filler, etc. are mentioned. Moreover, since the resist thickness is generally as thin as 1 to 10 μm, a small filler size is preferable. Although it is preferable to use a material having a small average particle size and cut coarse particles, the coarse particles can be crushed during dispersion or removed by filtration.

  Other additives include, for example, photopolymerizable resins (photopolymerization initiators), polymerization inhibitors, colorants (dyes, pigments, coloring pigments), thermal polymerization initiators, and crosslinking agents such as epoxies and urethanes. Can be mentioned.

  In the printed board processing process of the present invention, for example, laser processing may be used, but in the case of laser processing, it is necessary to impart a laser ablation property to the resist material. As the laser processing machine, a carbon dioxide laser, excimer laser, UV-YAG laser, or the like is selected. These laser processing machines have various intrinsic wavelengths, and productivity can be improved by using a material having a high absorption rate for these wavelengths. Among them, the UV-YAG laser is suitable for fine processing, and the laser wavelength is 3rd harmonic 355 nm and 4th harmonic 266 nm. Therefore, it is desirable that the absorption rate is high with respect to these wavelengths. On the other hand, a material having a somewhat low absorption rate may be preferable. Specifically, for example, when a resist having a low UV absorption rate is used, the UV light transmits through the resist, so that energy can be concentrated on the underlying insulating layer processing. That is, since the advantages differ depending on the absorption rate of laser light, it is preferable to use a resist in which the absorption rate of the laser beam of the resist is adjusted according to the situation.

  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.

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

  Moreover, as said resin film, in addition to the above, the following are mentioned. For example, the following are mentioned as a resist material which comprises the said resin film.

  Properties required for the resist material constituting the resin coating include, for example, (1) resistance to a liquid (plating nucleation chemical) in which an insulating substrate on which the resin coating is formed is immersed in a catalyst deposition step described later. (2) The film coating process described later, for example, the resin film (resist) can be easily removed by the step of immersing the insulating base material on which the resin film is formed in alkali, and (3) High film formability. (4) easy dry film (DFR) formation, (5) high storage stability, and the like.

  As the plating nucleating chemical solution, as will be described later, for example, in the case of an acidic Pd—Sn colloid catalyst system, all are acidic (pH 1-2) aqueous solutions. Moreover, in the case of an alkaline Pd ion catalyst system, the catalyst imparting activator is a weak alkali (pH 8 to 12), and the others are acidic. From the above, it is necessary to withstand pH 1 to 11, and preferably pH 1 to 12, as the resistance to the plating nucleating solution. Note that being able to withstand is that when a sample on which a resist is formed is immersed in a chemical solution, swelling and dissolution of the resist are sufficiently suppressed, and the resist serves as a resist. The immersion temperature is generally room temperature to 60 ° C., the immersion time is 1 to 10 minutes, and the resist film thickness is generally about 1 to 10 μm, but is not limited thereto.

  As the alkali stripping chemical used in the film removal step, as will be described later, for example, an aqueous NaOH solution or an aqueous sodium carbonate solution is common. Its pH is 11 to 14, and it is desirable that the resist film can be easily removed preferably at pH 12 to 14. The NaOH aqueous solution concentration is generally about 1 to 10%, the processing temperature is room temperature to 50 ° C., the processing time is 1 to 10 minutes, and the immersion or spray treatment is generally performed, but is not limited thereto.

  Since a resist is formed on an insulating material, film formability is also important. A uniform film formation without repelling or the like is necessary. Moreover, although it is made into a dry film for the simplification of a manufacturing process, reduction of material loss, etc., the flexibility of a film is required in order to ensure handling property. Also, a dry film resist is pasted on the insulating material with a laminator (roll, vacuum). The pasting temperature is room temperature to 160 ° C., and the pressure and time are arbitrary. Thus, adhesiveness is required at the time of pasting. For this reason, the resist formed into a dry film is generally used as a three-layer structure sandwiched by a carrier film and a cover film to prevent dust from adhering, but is not limited thereto.

  The best preservation is that it can be stored at room temperature, but it must also be refrigerated or frozen. As described above, it is necessary to prevent the composition of the dry film from being separated at low temperatures or to be cracked due to a decrease in flexibility.

  The resin composition of the resist material may include a main resin (binder resin) as an essential component, and at least one of oligomers, monomers, fillers, and other additives may be added.

  The main resin is preferably a linear polymer with thermoplastic properties. In order to control fluidity and crystallinity, it may be branched by grafting. The molecular weight is about 1,000 to 500,000 in terms of number average molecular weight, preferably 5,000 to 50,000. If the molecular weight is too small, the flexibility of the film and the resistance to the plating nucleation solution (acid resistance) tend to decrease. Moreover, when molecular weight is too large, there exists a tendency for the sticking property at the time of using alkali peelability or a dry film to worsen. Furthermore, a crosslinking point may be introduced to improve resistance to plating nucleus chemicals, suppress thermal deformation during laser processing, and control flow.

  As the composition of the main resin, (a) a carboxylic acid or acid anhydride monomer having at least one polymerizable unsaturated group in the molecule and (b) (a) a monomer that can be polymerized with the monomer It is obtained by polymerizing. Examples of known techniques include those described in JP-A-7-281437, JP-A-2000-231190, and JP-A-2001-201851. Examples of (a) include, for example, (meth) acrylic acid, fumaric acid, cinnamic acid, crotonic acid, itaconic acid, maleic anhydride, maleic acid half ester, butyl acrylate, etc., alone or 2 More than one type may be combined. Examples of (b) are generally non-acidic and have (one) polymerizable unsaturated group in the molecule, but are not limited thereto. It is selected so as to maintain various properties such as resistance in the plating process and flexibility of the cured film. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert. -Butyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylates, etc. are mentioned. Further, esters of vinyl alcohol such as vinyl acetate, (meth) acrylonitrile, styrene, or a polymerizable styrene derivative may be used. It can also be obtained by polymerization of only a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Furthermore, a monomer having a plurality of unsaturated groups is selected as a monomer used in the polymer so that it can be three-dimensionally cross-linked, such as an epoxy group, a hydroxyl group, an amino group, an amide group, a vinyl group in the molecular skeleton. Reactive functional groups can be introduced. When the carboxyl group is contained in the resin, the amount of the carboxyl group contained in the resin is preferably 100 to 2000, preferably 100 to 800, as an acid equivalent. Here, the acid equivalent means the weight of the polymer having 1 equivalent of a carboxyl group therein. When the acid equivalent is too low, there is a tendency that compatibility with a solvent or other composition is lowered or plating pretreatment solution resistance is lowered. Moreover, when an acid equivalent is too high, there exists a tendency for peelability to fall. Moreover, the composition ratio of (a) monomer is 5 to 70% by weight.

  Any monomer or oligomer may be used as long as it is resistant to plating nucleation chemicals and can be easily removed with alkali. In order to improve the sticking property of the dry film (DFR), it can be considered that it is used as a plasticizer as a tackifier. Further, a crosslinking agent is added to increase various resistances. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert. -Butyl (meth) acrylate, 2-hydroxylethyl (meth) acrylate, 2-hydroxylpropyl (meth) acrylates, etc. are mentioned. In addition, esters of vinyl alcohol such as vinyl acetate, (meth) acrylonitrile, styrene, or a polymerizable styrene derivative are also included. It can also be obtained by polymerization of only a carboxylic acid or acid anhydride having one polymerizable unsaturated group in the molecule. Furthermore, a polyfunctional unsaturated compound may be included. Any of the above monomers or oligomers obtained by reacting the monomers may be used. In addition to the above monomers, it is possible to include two or more other photopolymerizable monomers. Examples of this monomer include 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Polyoxyalkylene glycol di (meth) acrylate such as polyoxyethylene polyoxypropylene glycol di (meth) acrylate, 2-di (p-hydroxyphenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, dipentaerythritol penta (Meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether tri (meth) acrylate, 2,2-bis (4-methyl) Methacryloxy pentaethoxy phenyl) propane, a polyfunctional (meth) acrylate containing urethane groups. Further, any of the above monomers or oligomers obtained by reacting the monomers may be used.

  Furthermore, you may contain a filler. The filler is not particularly limited. Specifically, for example, silica, aluminum hydroxide, magnesium hydroxide, calcium carbonate, clay, kaolin, titanium oxide, barium sulfate, alumina, zinc oxide, talc, mica, glass, titanic acid. Examples include potassium, wollastonite, magnesium sulfate, aluminum borate, and an organic filler. Moreover, since the resist thickness is generally as thin as 1 to 10 μm, a small filler size is preferable. Although it is preferable to use a material having a small average particle size and cut coarse particles, the coarse particles can be crushed during dispersion or removed by filtration.

  Other additives include, for example, photopolymerizable resins (photopolymerization initiators), polymerization inhibitors, colorants (dyes, pigments, coloring pigments), thermal polymerization initiators, and crosslinking agents such as epoxies and urethanes. Can be mentioned.

  In the printed board processing process of the present invention, for example, laser processing may be used, but in the case of laser processing, it is necessary to impart a laser ablation property to the resist material. As the laser processing machine, a carbon dioxide laser, excimer laser, UV-YAG laser, or the like is selected. These laser processing machines have various intrinsic wavelengths, and productivity can be improved by using a material having a high absorption rate for these wavelengths. Among them, the UV-YAG laser is suitable for fine processing, and the laser wavelength is 3rd harmonic 355 nm and 4th harmonic 266 nm. Therefore, it is desirable that the absorption rate is high with respect to these wavelengths. On the other hand, a material having a somewhat low absorption rate may be preferable. Specifically, for example, when a resist having a low UV absorption rate is used, the UV light transmits through the resist, so that energy can be concentrated on the underlying insulating layer processing. That is, since the advantages differ depending on the absorption rate of laser light, it is preferable to use a resist in which the absorption rate of the laser beam of the resist is adjusted according to the situation.

<Circuit groove forming process>
The circuit groove forming step is a step of forming the circuit groove 3 in the insulating base material 1.

  A method for forming the circuit groove 3 is not particularly limited. Specifically, for example, on the insulating base material 1 on which the resin coating 2 is formed, from the outer surface side of the resin coating 2, machining such as laser processing and dicing processing, and mechanical processing such as embossing processing, etc. The method of forming the circuit groove 3 of a desired shape and depth by giving is mentioned. In the case of forming a highly accurate fine circuit, it is preferable to use laser processing. According to laser processing, the cutting depth or the like can be freely adjusted by changing the output of the laser or the like. Further, as the stamping process, for example, a stamping process using a fine resin mold used in the field of nanoimprinting can be preferably used.

  Moreover, a through hole 4 for forming a via hole or the like may be formed as a part of the circuit groove 3.

  By this step, the shape and depth of the circuit groove 3 and the diameter and position of the through hole 4 are defined. The circuit groove forming step may be performed by digging more than the thickness of the resin coating 2, or may be performed by digging the thickness of the resin coating 2 or exceeding the thickness of the resin coating 2.

  The width of the circuit groove 3 formed in the circuit groove forming step is not particularly limited. When laser processing is used, a fine circuit having a line width of 20 μm or less can be easily formed. The depth of the circuit groove is the depth of the electric circuit formed in the present embodiment when the step is eliminated between the electric circuit and the insulating base material by fill-up plating.

<Catalyst deposition process>
The catalyst deposition step is a step of depositing a plating catalyst or a precursor thereof on the surface of the circuit groove 3 and the surface of the resin coating 2. At this time, when the through hole 4 is formed, the plating catalyst or its precursor is also applied to the inner wall surface of the through hole 4.

  The plating catalyst or its precursor 5 is a catalyst that is applied to form an electroless plating film only in a portion where it is desired to form an electroless plating film 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 removing the resin film. 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 of depositing the plating catalyst or its precursor 5 include a method of treating with an acidic Pd—Sn colloidal solution treated under acidic conditions of pH 1 to 3 and then treating with an acid solution. It is done. 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%. Then, Pd and Sn are aggregated and adsorbed by further immersing in an acidic plating catalyst 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 plating catalyst colloid solution, a well-known acidic Pd-Sn colloid catalyst solution etc. can be used, and the commercially available plating process using an acidic plating catalyst colloid solution may be used. Such a process is systematized and sold by Rohm & Haas Electronic Materials Co., Ltd., for example.

  By such a catalyst deposition process, the plating catalyst or its precursor 5 can be deposited on the surface of the circuit groove 3, the inner wall surface of the through hole 4, and the surface of the resin coating 2.

<Film removal process>
The coating removal step is a step of removing the resin coating 2 from the insulating base material 1 subjected to the catalyst deposition step.

  The method for removing the resin coating 2 is not particularly limited. Specifically, for example, after the resin film 2 is swollen with a predetermined solution (swelling liquid), the resin film 2 is peeled off from the insulating substrate 1, or the resin with a predetermined solution (swelling liquid). A method of removing the resin film 2 from the insulating substrate 1 after the film 2 is swollen and further partially dissolved, and a method of removing the resin film 2 by dissolving it with a predetermined solution (swelling liquid) Etc. The swelling liquid is not particularly limited as long as it can swell the resin film 2. The swelling or dissolution is performed by immersing the insulating base material 1 covered with the resin coating 2 in the swelling liquid for a predetermined time. And removal efficiency may be improved by irradiating with ultrasonic waves during the 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 used without substantially decomposing or dissolving the insulating substrate 1 and the plating catalyst or its precursor 5. Any liquid that can be swollen or dissolved can be used without particular limitation. Moreover, the liquid which can swell so that the said swellable resin film 2 can be peeled easily is preferable. Such a swelling liquid can be appropriately selected depending on the type and thickness of the swellable resin film 2. Specifically, for example, the swelling resin film is an elastomer such as a diene elastomer, an acrylic elastomer, and a polyester elastomer, or (a) a carboxylic acid or an acid having at least one polymerizable unsaturated group in the molecule. A polymer resin obtained by polymerizing at least one monomer of an anhydride and (b) at least one monomer that can be polymerized with the monomer (a) or the polymer resin In the case where the resin composition is formed from a carboxyl group-containing acrylic resin, an alkaline aqueous solution such as a sodium hydroxide aqueous solution having a concentration of about 1 to 10% 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 degree of swelling of less than 50%, preferably 40% or less under acidic conditions. Yes, such that the degree of swelling is 50% or more under alkaline conditions, for example, elastomers such as diene elastomers, acrylic elastomers, and polyester elastomers, (a) at least one polymerizable unsaturated group in the molecule Polymer resin obtained by polymerizing at least one monomer of carboxylic acid or acid anhydride having at least one monomer and (b) at least one monomer that can be polymerized with monomer (a) Alternatively, it is preferably formed from a resin composition containing the polymer resin and a carboxyl group-containing acrylic resin. 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.

<Plating process>
The plating process is a process of performing an electroless plating process on the insulating substrate 1 after the resin film 2 is removed.

  As a method of the electroless plating treatment, the insulating base material 1 partially coated with the plating catalyst or its precursor 5 is immersed in an electroless plating solution, and the plating catalyst or its precursor 5 is applied. For example, a method of depositing an electroless plating film (plating layer) only on the portion 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.

  By the plating process, an electroless plating film is deposited only on the portion where the plating catalyst or its precursor 5 remains on the surface of the insulating substrate 1. 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.

<Inspection process>
In the method for manufacturing a circuit board according to the present embodiment, the resin coating 2 contains a fluorescent material, and after the coating removal step, the coating removal failure is inspected using light emitted from the fluorescent material. An inspection process may be further included. That is, by including a fluorescent substance in the resin film 2, the film removal failure is caused by using light emitted from the fluorescent substance by irradiating the inspection target surface with ultraviolet light or near ultraviolet light after the film removal step. It is possible to inspect the presence or absence of the film and the location where the film removal is defective. In the manufacturing method of the present embodiment, an electric circuit having an extremely narrow line width and line interval can be formed.

  In the case where an electric circuit having an extremely narrow line width and line interval is formed, for example, as shown in FIG. 3, a resin film is completely formed between adjacent electric circuits 8 formed on the surface of the insulating base 1. There is a concern that it will remain without being removed. In such a case, an electroless plating film is formed in that portion, which may cause migration or short circuit. Even in such a case, if the inspection step is provided, it is possible to inspect the presence / absence of a film removal failure and the location of the film removal failure. FIG. 3 is an explanatory diagram for explaining an inspection process for inspecting defective film removal by using a light emission from the fluorescent substance by adding a fluorescent substance to the resin film.

  The fluorescent substance that can be contained in the resin film 2 used in the inspection step is not particularly limited as long as it exhibits light emission characteristics when irradiated with light from a predetermined light source. Specific examples thereof include Fluoresceine, Eosine, Pyroline G, and the like.

  The portion where light emission from the fluorescent material is detected by this inspection process is a portion where the residue 2a of the resin film 2 remains. Therefore, by removing the portion where luminescence is detected, it is possible to suppress the formation of an electroless plating film on that portion. Thereby, generation | occurrence | production of a migration, a short circuit, etc. can be suppressed beforehand.

<Desmear treatment process>
The circuit board manufacturing method according to the present embodiment further includes a desmear treatment step of performing a desmear treatment after the plating treatment step, specifically, before or after the fill-up plating. May be. By applying desmear treatment, unnecessary resin adhered to the electroless plating film can be removed. Further, when assuming a multilayer circuit board provided with the obtained circuit board, the surface of the insulating base material where the electroless plating film is not formed is roughened, and the adhesion with the upper layer of the circuit board is improved. Can be improved. Further, a desmear process may be performed on the via bottom. By doing so, unnecessary resin adhered to the via bottom can be removed. Moreover, it does not specifically limit as said desmear process, A well-known desmear process can be used. Specifically, the process etc. which are immersed in a permanganic acid solution etc. are mentioned, for example.

  Through the steps as described above, a circuit board 10 as shown in FIG. 1E is formed.

[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, a method for manufacturing the three-dimensional circuit board according to the second embodiment will be described.

  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. 4B, a circuit groove 3 having a depth equal to or greater than the thickness of the resin coating 2 is formed with the outer surface of the resin coating 2 as a reference. The method for forming the circuit groove 3 is not particularly limited. Specifically, for example, the same formation method as in the first embodiment can be used. The circuit groove 3 defines a portion where an electroless plating film is formed by electroless plating, that is, a portion where an electric circuit is formed. This step corresponds to a circuit groove forming step.

  Next, as shown in FIG. 4C, a plating catalyst or its precursor 5 is deposited on the surface of the circuit groove 3 and the surface of the resin film 2 on which the circuit groove 3 is not formed. The method for depositing the plating catalyst or its precursor 5 is not particularly limited. Specifically, for example, the same method as in the first embodiment can be used. This step corresponds to a catalyst deposition step. By such a catalyst deposition treatment, the plating catalyst or its precursor 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 removed from the three-dimensional insulating base material 51. By doing so, the plating catalyst or its precursor 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 plating catalyst or its precursor 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. The method for removing the resin film 2 is not particularly limited. Specifically, for example, the same method as in the first embodiment can be used. This process corresponds to a film removal process.

  Next, as shown in FIG. 4E, electroless plating is performed on the three-dimensional insulating base material 51 from which the resin film 2 has been removed. By doing so, the electroless plating film 6 is formed only in the portion where the plating catalyst or its precursor 5 remains. That is, an electroless plating film 6 that becomes an electric circuit is formed in a portion where the circuit groove 3 and the through hole 4 are formed. The formation method of the electroless plating film 6 is not particularly limited. Specifically, for example, the same formation method as in the first embodiment can be used. 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 can form an electric circuit with high accuracy even if the line width and line interval of the electric circuit formed on the insulating base material are narrow. In addition, the circuit board according to the present embodiment is 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
A 2 μm thick styrene-butadiene copolymer (SBR) film was formed on the surface of a 100 μm thick epoxy resin substrate (R1766 manufactured by Panasonic Electric Works Co., Ltd.). The coating is formed on the main surface of the epoxy resin base material with methyl ethyl ketone (MEK) suspension (manufactured by Nippon Zeon Co., Ltd., acid equivalent 600, particle diameter 200 nm, solid content) of styrene-butadiene copolymer (SBR). 15%) was applied and dried at 80 ° C. for 30 minutes.

  And the groove | channel formation process of the shape as shown to FIG. 1 (B) of width 20 micrometers and depth 20 micrometers was performed with respect to the epoxy resin base material in which the film was formed by laser processing. For laser processing, MODEL 5330 manufactured by ESI equipped with a UV-YAG laser was used.

  Next, the epoxy resin base material in which the groove was formed was immersed in a cleaner conditioner (surfactant solution, pH <1: C / N 3320 manufactured by Rohm & 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. And the pre-dip process was performed using PD404 (Shipley Far East Co., Ltd. product, pH <1). Then, by immersing in an acidic Pd-Sn colloidal solution (CAT44, manufactured by Shipley Far East Co., Ltd.) having a pH of 1 containing stannous chloride and palladium chloride, the palladium serving as the core of electroless copper plating is tin-palladium. It was made to adsorb | suck to an epoxy resin base material in the state of a colloid.

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

  An electroless copper plating film having a thickness of 5 μm was deposited by the electroless copper plating treatment. When the surface of the epoxy base material treated with electroless copper plating was observed with an SEM (scanning microscope), an electroless plating film was accurately formed only on the cut portion.

  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)
Instead of methyl ethyl ketone (MEK) suspension (manufactured by Nippon Zeon Co., Ltd., acid equivalent 600, particle size 200 nm, solid content 15%) of styrene-butadiene copolymer (SBR), a carboxyl group-containing polymer (Nippon Zeon Co., Ltd.) ), Acid equivalent 500, weight average molecular weight 25000, solid content 20%).

  At this time, the degree of swelling with respect to a 5% aqueous solution of sodium hydroxide at pH 14 was 1000%. On the other hand, the degree of swelling with respect to a 5% hydrochloric acid aqueous solution at pH 1 was 30%.

  As described above, when the manufacturing method according to the present embodiment is used, the plating catalyst can be deposited only on the portion of the substrate surface where the circuit is to be formed by peeling the swellable resin film. Therefore, an electroless plating film is accurately formed only on the portion where the plating catalyst is deposited. Further, since the swellable resin film can be easily peeled off by the swelling action, the film removal step can be easily and accurately performed.

  And the cross section perpendicular | vertical with respect to the longitudinal direction of the formed circuit groove | channel of the circuit board obtained by making it above was observed using SEM (scanning microscope). The formed electroless plating film had a thickness T of about 5 μm and a circuit groove depth D of about 20 μm. At this time, T / D was about 0.25.

DESCRIPTION OF SYMBOLS 1,21 Insulation base material 2,22 Resin film 3,23 Circuit groove 4 Through-hole 5 Plating catalyst or its precursor 6 Electroless plating film (electric circuit)
DESCRIPTION OF SYMBOLS 10 Circuit board 11 Filler 51 Three-dimensional insulation base material 60 Circuit board

Claims (17)

A film forming step of forming a resin film on the surface of the insulating substrate;
Forming a recess having a depth exceeding the thickness of the resin coating on the basis of the outer surface of the resin coating, thereby forming a circuit groove having a desired shape and depth on the insulating substrate; and
A catalyst deposition step of depositing a plating catalyst or a precursor thereof on the surface of the circuit groove and the surface of the resin coating;
A film removing step for removing the resin film from the insulating substrate;
An electroless plating is performed on the insulating base material from which the resin coating has been removed, and a plating treatment step of forming an electroless plating film is provided.
The film removal step is a step of peeling the resin film from the insulating substrate after the resin film is swollen with an alkaline solution or after part of the resin film is dissolved with an alkaline solution,
The catalyst deposition step comprises a step of treating in an acidic catalyst metal colloid solution,
The resin film has a swelling degree with respect to the acidic catalyst metal colloid solution of less than 50%, and a swelling degree with respect to the alkaline solution is 50% or more,
In the plating process, the electroless plating film is formed so that the thickness of the electroless plating film is 0.5 or less with respect to the depth of the circuit groove. .   2. The circuit board manufacture according to claim 1, wherein in the plating step, the electroless plating film is formed such that a thickness of the electroless plating film is 0.25 or more with respect to a depth of the circuit groove. Method.   The method for manufacturing a circuit board according to claim 1, wherein the coating film removing step is a step of dissolving and removing the resin coating film with the alkaline solution. Wherein the resin coating, wherein after the elastomer suspension or emulsion was coated on an insulating surface of a substrate, method of manufacturing a circuit board according to any one of claims 1 to 3, which is a resin film formed by drying . The resin coating method for producing a circuit board according to the resin coating formed on the supporting substrate in any one of claims 1 to 3, which is a resin film formed by transferring to the insulating substrate surface . The method for producing a circuit board according to claim 4 , wherein the elastomer is selected from the group consisting of a diene elastomer, an acrylic elastomer, and a polyester elastomer having a carboxyl group. The method for producing a circuit board according to claim 6 , wherein the diene elastomer is a styrene-butadiene copolymer. The method for manufacturing a circuit board according to any one of claims 1 to 7 , wherein the resin coating includes a resin composed of an acrylic resin having a carboxyl group with an acid equivalent of 100 to 800 as a main component. The resin coating comprises (a) at least one monomer of carboxylic acid or acid anhydride having at least one polymerizable unsaturated group in the molecule, and (b) polymerizing with the (a) monomer. The production of a circuit board according to any one of claims 1 to 3 , comprising a polymer resin obtained by polymerizing at least one monomer capable of being polymerized or a resin composition containing the polymer resin. Method. The method for producing a circuit board according to claim 9 , wherein an acid equivalent of the polymer resin is 100 to 800. The thickness of the resin coating method for producing a circuit board according to any one of claims 1-10 is 10μm or less. Method of manufacturing a circuit board according to any one of claims 1 to 11, the width of the circuit groove has a following portion 20 [mu] m. The circuit groove forming step, the manufacturing method of the circuit board according to any one of claims 1 to 12, which is a step of forming a circuit grooves by laser processing. The circuit groove forming step, circuit substrate manufacturing method according to any one of claims 1 to 12, which is a step of forming a circuit groove with a mold押法. The method for manufacturing a circuit board according to any one of claims 1 to 14 , wherein in the circuit groove forming step, a through hole is formed in the insulating base material when the circuit groove is formed. It said insulating substrate has a stepped surface formed in a stepped shape, manufacturing method of circuit board according to any one of claims 1 to 15, wherein the insulating substrate surface is the stepped surface. The resin coating contains a fluorescent substance,
After the film removing step, the manufacturing method of the circuit board according to any one of claims 1 to 16, further comprising an inspection step for inspecting the film removal failure by using a light emitted from the fluorescent substance.

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