JP5350138B2 - Electric circuit manufacturing method and electric circuit board obtained by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing an electric circuit capable of maintaining high mechanical strength and adhesion strength even when the electric circuit with narrow line width and line interval are formed. <P>SOLUTION: The method of producing an electric circuit includes a film-forming step of forming a resin film 2 on the surface of an insulative substrate 1, a circuit pattern forming step of forming grooves and/or holes having desired shape and depth by performing laser processing or mechanical processing to the insulative substrate from the outer surface of the resin film to form a circuit pattern part, a catalyst-depositing step of depositing a plating catalyst or its precursor on the surface of the circuit pattern part of the insulative substrate and the surface of the resin film 2 coating the insulative substrate 1, a film-peeling step of peeling the resin film from the insulative substrate, and a plating processing step of performing electroless deposition to the insulative substrate from which the resin film is peeled, and in the circuit pattern forming step, a method for plating reinforcement structure at least at a part of the circuit pattern part is used. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

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

  2. Description of the Related Art In recent years, functions of mobile information terminal devices such as mobile phones, computers and peripheral devices, and various information home appliances have been rapidly increasing in functionality. Accordingly, there is an increasing demand for increasing the density of electric circuits in electric circuit boards mounted on these electric devices. In order to realize such high density of the electric circuit board, a method for forming an electric circuit having a narrower line width and line spacing is required.

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

  The subtractive method is a method in which the metal foil on the surface of the metal foil-clad laminate is etched to leave only the portion where the electric circuit is to be formed, and the other portion is removed. This method is disadvantageous in terms of manufacturing costs because it wastes part of the metal that is removed. On the other hand, in the additive method, a conductive layer is formed only on a circuit formation portion using electroless plating. This method is preferable because there is no waste of resources.

  An outline of a method of forming a metal wiring by a full additive method, which is a typical representative additive method, will be described with reference to process cross-sectional views of FIGS. 6A to 6E.

  First, as shown in FIG. 6A, the plating catalyst 102 is deposited on the surface of the insulating base material 100 provided with the through holes 101. Note that the surface of the insulating substrate 100 is roughened in advance. Next, as shown in FIG. 1B, a photoresist layer 103 is formed. Next, as shown in FIG. 1C, exposure is performed through a photomask 110 in which a predetermined circuit pattern is formed on the surface of the photoresist layer 103. Next, as shown in FIG. 1D, the circuit pattern is developed. Then, as shown in FIG. 1E, the metal wiring 104 is formed by performing electroless copper plating on the circuit pattern portion and the through hole formed by development. An electric circuit is formed on the surface of the insulating substrate 100 by such a process.

  According to the conventional general additive method as described above, since the plating catalyst 102 is deposited on the entire surface of the insulating base material 100, the following problems occur. That is, when the photoresist layer 103 is developed with high accuracy in accordance with the pattern of the photomask, it is possible to accurately form plating only on the portion not protected by the photoresist. However, when the photoresist layer 103 is not developed with high accuracy, the plating catalyst 102 is deposited on the entire surface of the insulating base material 100, so that the original plating as shown in FIG. Unnecessary plated portions 105 may remain in portions that are not desired. Such an unnecessary plated portion 105 causes a short circuit or migration between adjacent circuits. Such a short circuit or migration is more likely to occur when an electric circuit having a narrow line width and line interval is formed.

  Patent Document 1 below 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. Then, after the first and second photosensitive resin layers are exposed through a photomask having a predetermined circuit pattern, the first and second photosensitive resin layers are developed. And after making a catalyst adsorb | suck to the whole surface containing the recessed part produced by image development, only an unnecessary catalyst is removed by dissolving alkali-soluble 2nd photosensitive resin with an alkaline solution. And the method of forming a circuit correctly only in the part in which a catalyst exists by performing electroless plating after that is described. However, according to such a method, 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, an alkaline solution is further added. The manufacturing process is very complicated, such as the need to dissolve the second photosensitive resin.

  Patent Document 2 below discloses the following method. First, a protective film of resin is coated on the insulating substrate (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, after forming an activation layer on the entire surface of the insulating substrate, the protective film is peeled off to remove the activation layer on the insulating substrate and leave the activation layer only on the inner wall surfaces of the trench and the through hole (third Process). 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 (fourth step).

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

  When an electric circuit having a narrow line width and line interval is formed in order to realize high density of the electric circuit using the conventional methods for manufacturing various electric circuits as described above, the following problems occur. That is, there is a problem that the strength of the metal wiring constituting the electric circuit becomes weaker as the line width and the line interval of the electric circuit become narrower. Such a decrease in the strength of the metal wiring causes a decrease in the reliability of the electronic device.

  Specifically, a problem that may occur in an electric circuit board mounted on a portable information terminal device such as a mobile phone will be described as an example. A relatively large LSI (Large Scale Integration) is mounted on an electric circuit board mounted on a portable information terminal device. Such an LSI is bonded to the land portion formed as a part of the circuit of the electric circuit board by solder bumps. Since the portable information terminal device is carried, there are many opportunities to receive an impact. When such an impact is applied, a force is applied to the mounted LSI, and the metal wiring constituting the land portion may be cut and damaged. Similarly, on the LSI side, the contact portion of the LSI substrate may be peeled off and damaged. As the line width and line spacing of an electrical circuit become narrower, such circuit damage is likely to occur.

  In order to solve such a problem, a method of reinforcing the metal wiring by partially increasing the line width of the circuit line can be considered. However, such a method cannot increase the density of the circuit. Further, in the circuit obtained by the subtractive method, the thickness of the metal wiring depends on the thickness of the copper foil, so that the metal wiring cannot be reinforced by increasing the film thickness.

  In order to solve such problems, the present invention provides an electrical circuit manufacturing method capable of maintaining high mechanical strength and adhesion strength even when an electrical circuit having a narrow line width and line spacing is formed. For the purpose.

  The method for producing an electric circuit of the present invention comprises a film forming step of forming a resin film on the surface of an insulating substrate, and a desired shape and laser processing or machining from the outer surface side of the resin film to the insulating substrate. A circuit pattern forming step for forming a circuit pattern portion by forming grooves and / or holes having a depth, and a plating catalyst on the surface of the circuit pattern portion of the insulating base and the surface of the resin film covering the insulating base Or a catalyst deposition process for depositing the precursor, a film peeling process for peeling the resin film from the insulating base, and a plating process for electroless plating the insulating base from which the resin film has been peeled. In the circuit pattern forming step, a plating reinforcement structure is formed on at least a part of the circuit pattern portion. According to such a manufacturing method, a circuit pattern portion having a desired depth and shape can be formed by laser processing or the like from the outer surface of the resin film formed on the insulating substrate. And after giving a plating catalyst to the whole surface of the insulating base material coat | covered with the resin film in which the circuit pattern was formed, the plating catalyst only of a circuit pattern part surface remains by peeling a resin film. Then, by applying electroless plating to the insulating base material, plating is formed only on the surface of the circuit pattern portion. In this case, an uneven shape that exhibits an anchor effect is formed on the surface of the circuit pattern portion, or a thick film plating is partially formed by deeply forming a groove only in a portion to be reinforced. By providing a dimensional reinforcing portion, it is possible to increase the mechanical strength and adhesion strength of a portion that is easily damaged by an electric circuit.

  Further, in the method for manufacturing an electric circuit, the circuit pattern portion includes at least one land portion for surface-mounting an electronic component and a circuit line portion formed integrally with the land portion. It is preferable that the shape is given to the land portion surface. A land portion on which an electronic component such as an LSI is mounted is a portion that is particularly easily cut or peeled by an impact. By imparting an uneven shape to the surface of the land portion that is vulnerable to such an impact, the adhesion of the metal wiring of the land portion is improved, thereby improving the mounting strength when an LSI or the like is mounted.

  In the method of manufacturing an electric circuit, the circuit pattern portion includes at least one land portion for surface mounting an electronic component and a circuit line portion formed integrally with the land portion, and the plating It is preferable that the reinforcing structure is formed by giving the groove depth of the land portion so as to be deeper than the groove depth of the circuit line portion. When an electric circuit board receives an impact with electronic components mounted, in a circuit pattern having a circuit line portion formed integrally with the land portion and the land portion, in the vicinity of the connection portion between the land portion and the circuit line portion. Cutting is easy to occur. In such a case, by providing a plating reinforcing structure so that the groove depth of the land portion is deeper than the groove depth of the circuit line portion, the plating formed on the land portion is plated on the circuit line portion. It can be formed thicker. Thereby, the connection part of a land part and a circuit wire part can be reinforced.

  In the method of manufacturing an electric circuit, the circuit pattern portion includes at least one land portion for surface mounting an electronic component and a circuit line portion formed integrally with the land portion, and the plating It is preferable that the reinforcing structure is formed by providing a protrusion shape on the groove outer periphery of the land portion. By imparting a protrusion shape to the outer periphery of the groove of the land portion, the mounting strength when mounting LSI or the like is further improved.

  The electric circuit board of the present invention has an electric circuit obtained by the manufacturing method.

  According to the manufacturing method of the present invention, an electric circuit capable of maintaining high mechanical strength and adhesion strength can be obtained even when an electric circuit having a narrow line width and line spacing is formed. In particular, the electrical circuit can be partially reinforced.

FIG. 1 is a process diagram for explaining a manufacturing method according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining a plating reinforcement structure formed in the manufacturing method according to the embodiment of the present invention. FIG. 3 is a schematic diagram for explaining another plating reinforcement structure formed in the manufacturing method according to the embodiment of the present invention. FIG. 4 is a schematic diagram for explaining another plating reinforcement structure formed in the manufacturing method according to the embodiment of the present invention. FIG. 5 is a schematic diagram for explaining a method of forming a plating reinforcement structure formed by the manufacturing method according to the embodiment of the present invention by embossing. FIG. 6 is a process diagram for explaining circuit pattern formation by a conventional typical additive method. FIG. 7 is an explanatory diagram for explaining a contour shape of a circuit formed by a conventional additive method. FIG. 8 is a schematic view showing an example of the surface irregularity shape. FIG. 9 is a schematic view showing another example of the surface uneven shape. FIG. 10 is a schematic diagram illustrating another example of the surface uneven shape. FIG. 11 is a schematic diagram illustrating another example of the surface uneven shape. FIG. 12 is a schematic view showing another example of the surface uneven shape.

[First Embodiment]
The electric circuit manufacturing method of the present embodiment includes a film forming step of forming a resin film on the surface of the insulating base, and a desired shape by laser processing or machining the insulating base from the outer surface side of the resin film. And forming a circuit pattern part by forming grooves and / or holes having a depth, and plating the surface of the circuit pattern part of the insulating base and the surface of the resin film covering the insulating base A catalyst deposition step for depositing a catalyst or a precursor thereof, a coating stripping step for stripping the resin coating from the insulating substrate, and a plating treatment step for performing electroless plating on the insulating substrate from which the resin coating has been stripped And in the circuit pattern forming step, a plating reinforcing structure is formed on at least a part of the circuit pattern portion.

  Hereinafter, the manufacturing method of this embodiment is demonstrated, referring drawings.

  FIG. 1 is a process diagram for explaining the manufacturing method of the present embodiment. In FIG. 1, 1 is an insulating substrate, 2 is a resin film, 3 is a circuit pattern portion, 4 is a plating catalyst, and 5 is electroless plating. Reference numeral 3a denotes an uneven plating reinforcing structure provided on a part of the surface of the circuit pattern 3.

  In the manufacturing method of this embodiment, as shown in FIG. 1A, first, a resin film 2 is formed on the surface of the substrate 1.

  As the insulating base 1, various organic substrates that can be used for manufacturing an electric circuit board are used. As specific examples of the organic substrate, an epoxy resin sheet, an acrylic resin sheet, a polycarbonate resin sheet, a polyimide resin sheet, and the like can be used without any particular limitation. In addition to the resin sheet, a molded body for forming a prepreg or a three-dimensional circuit board in which a fiber substrate is impregnated with a thermosetting resin can be preferably used. Although the thickness of the insulating base material 1 is not specifically limited, For example, it is preferable that it is about 10-200 micrometers, and also about 20-100 micrometers.

  The resin film 2 is formed by applying a liquid material to the main surface of the insulating base material 1 and then drying or bonding a previously formed resin film to the main surface of the insulating base material 1.

  As the resin film 2, a resin film that can be easily removed from the surface of the insulating base material 1 by swelling or dissolving with a predetermined liquid in a film removal step described later can be preferably used. Specifically, for example, a soluble resin that can be easily dissolved by an organic solvent or an alkaline solution, and a swellable resin that can be swollen by a predetermined solvent. Among these, a swellable resin is particularly preferable because accurate removal is easy.

  As the swellable resin film, a resin film having a degree of swelling with respect to the swelling liquid of 50% or more, more preferably 100% or more and 1000% or less can be preferably used. When the degree of swelling is too low, the swellable resin film tends to be difficult to peel, and when it is too high, the film strength is reduced, and the film tends to be difficult to peel due to tearing when peeling. There is. Such a swellable resin insulates the film formed by applying an elastomeric suspension or emulsion to the main surface of the insulating substrate 1 and then drying, or applying the suspension to the support substrate and then drying. It can be formed by transferring to the main surface of the substrate 1.

  Specific examples of such elastomers include diene elastomers such as styrene-butadiene copolymers, acrylic elastomers such as acrylic ester copolymers, and polyester elastomers. According to such an elastomer, a swellable resin film having a desired swelling degree can be easily formed by adjusting the degree of crosslinking or gelation of the elastomer resin particles dispersed as a suspension or emulsion.

  The coating method is not particularly limited, and conventionally known spin coating methods, bar coater methods, and the like can be used without particular limitation.

  The thickness of the resin film 2 is 10 μm or less, further 5 μm or less, preferably 0.1 μm or more, and more preferably 1 μm or more. When the thickness of the resin film 2 is too thick, the accuracy of grooves and / or holes formed by laser processing or machining tends to decrease. When the thickness is too thin, the thickness of the uniform film It tends to be difficult to form a resin film.

  Next, as shown in FIG. 1B, a circuit pattern is formed by forming a groove and / or a hole having a desired shape and depth by laser processing or machining the insulating base material 1 from the outer surface side of the resin film 2. Part 3 is formed. At this time, the plating reinforcing structure 3 a is formed on at least a part of the surface of the circuit pattern portion 3. (Circuit pattern formation process).

  For example, when forming an electric circuit having a land portion for surface mounting an electronic component such as an LSI and a circuit line portion formed integrally with the land portion, the land portion on which the electronic component is mounted is , Cutting and peeling tend to occur easily due to impact. In such a case, the mounting strength when the electronic component is mounted can be improved by providing the plating reinforcement structure on the land portion that is vulnerable to impact. According to the method of the present embodiment, it is possible to easily form the plating reinforcement structure 3a that can partially reinforce the electric circuit.

  For the formation of the circuit pattern portion 3, mechanical processing such as laser processing, dicing processing, and embossing processing is used. In order to form a fine circuit with high accuracy, it is preferable to use laser processing. Further, as the stamping process, a stamping process using a fine resin mold as used in the field of nanoimprinting can be preferably used.

  An example of the plating reinforcement structure formed in at least a part of the circuit pattern portion 3 is shown in FIGS.

  FIG. 2 shows a plated reinforcing structure having a surface concavo-convex shape 20 formed for the purpose of imparting an anchor effect. 2A is an enlarged top view when plating is formed on the circuit pattern having the land portion 21 and the circuit line portion 22 formed integrally with the land portion 21, and FIG. 2B is an AA ′ view of FIG. 2A. It is a schematic diagram of a cross section. By forming such a surface concavo-convex shape 20 when forming a circuit pattern on an insulating substrate, the adhesion of plating formed in an electroless plating process described later can be improved by an anchor effect.

  As the surface unevenness shape 20 as shown in FIG. 2, it is preferable to form unevenness such that, for example, the ten-point average roughness (Rz) is about 0.1 to 20 μm, and further about 1 to 10 μm. By forming such a concavo-convex shape 20 on the surface of the portion of the circuit pattern portion to be reinforced, the wiring circuit of the portion can be sufficiently reinforced.

  Here, Rz is a ten-point average roughness defined by JIS B 0601: 2001. As the measuring method, for example, it can be measured using a scanning confocal laser microscope, a surface roughness measuring machine, an atomic force microscope, and the like. Specifically, it can be measured using a scanning confocal laser microscope (LEXT OLS3000 manufactured by Olympus Corporation) or the like.

  FIG. 3 shows a plated reinforcing structure having a structure 30 for forming a thick plating by increasing the groove depth of a portion to be reinforced of the electric circuit to be formed. 3A is an enlarged top view when plating is formed on a circuit pattern having a land portion 31 and a circuit line portion 32 formed integrally with the land portion 31, and FIG. 3B is an AA ′ view of FIG. 3A. It is a schematic diagram of a cross section. When the circuit pattern is formed on the insulating substrate, by increasing the groove depth of the portion to be reinforced, the plating of the portion to be reinforced can be thickened and the adhesion of the plating of the portion can be improved.

  Further, as shown in FIG. 3, the structure in which the groove depth of the portion to be reinforced is deepened to form a thick plating is 1 to 10 compared with the thickness of the portion of the reinforced portion where the plating thickness is not reinforced. It is preferable to form the film so as to have a thickness that is twice or even about 2 to 5 times. By forming the groove so that the plating thickness of the portion to be reinforced becomes thick in this way, the wiring circuit of the portion can be sufficiently reinforced.

  FIG. 4 is an enlarged top view when plating is formed on a circuit pattern having a land portion 41 and a circuit line portion 42 formed integrally with the land portion 41, and a protrusion 40 is formed on the land portion 41. FIG. The protruding portion 40 improves the adhesion of the land portion 41.

  The above-described plating reinforcement structure can be formed when a circuit pattern is formed using laser processing or machining. Specifically, when the plating reinforcement structure as shown in FIG. 2 is formed using laser processing, a circuit pattern portion having a land portion 21 and a circuit line portion 22 formed integrally with the land portion 21. 3 is formed, only the surface of the formed land portion 21 can be intermittently irradiated with a laser to give the uneven shape 20. In the case of using embossing, as shown in FIG. 5, from the outer surface side of the resin film 2 using a male mold 50 for forming a circuit pattern having an uneven shape 20 in one region of the surface. By embossing toward the insulating substrate 1, the concavo-convex shape 20 is imparted.

  Further, the shape of the surface uneven shape 20 is not particularly limited as long as it is an uneven shape capable of providing an anchor effect, but the shape of the concave portion of the surface uneven shape 20 is circular when viewed from above the surface of the groove. It is preferable that it is at least any one of a 1 stroke drawing shape. That is, it is preferable that the concave portions do not intersect (do not contact).

  When the shape of the concave portion of the surface concavo-convex shape 20 is a shape in which the concave portions intersect with each other, the concave portion tends not to be suitably formed. In particular, when the plating reinforcement structure as shown in FIG. 2 is formed by using laser processing, the laser processing is performed twice or more on the same portion of the surface of the land portion 21. Specifically, for example, in the case of a lattice shape, the location of the lattice point is subjected to laser processing twice, and the depth of that portion is about twice that of the portion other than the lattice point. Depending on the thickness of the insulating substrate 1, there is a risk of penetration. Moreover, even if it is a case where the plating reinforcement structure as shown in FIG. 2 is formed by embossing using the male mold 50, the vicinity of the portion where the recesses intersect if the recesses intersect. The shape of the film tends to be complicated, and there is a tendency that it is not suitably formed.

  Therefore, if the shape of the concave portion of the surface uneven shape 20 is a shape in which the concave portions do not intersect with each other, the surface uneven shape 20 can be suitably formed.

  Next, a specific example of a suitable shape of the concave portion of the surface uneven shape 20 will be described.

  Specific examples of the shape of the concave portion of the surface concavo-convex shape 20 include the shapes shown in FIGS. 8 to 12 are schematic views showing examples of surface irregularities. 8A to 12A are enlarged top views of the insulating base material on which the uneven surface shape 20 is formed, and FIGS. 8B to 12B are schematic views of AA ′ cross sections of FIGS. 8A to 12A, respectively. It is. Further, the shape of the surface uneven shape 20 is not limited to the shape shown here.

  As an example (first example) of the surface uneven shape 20, as shown in FIG. 8, the concave portion 21 a is circular when viewed from above the surface of the groove, and the circular concave portion 20 a And a plurality of zigzag-shaped ones. Further, FIG. 8 is a schematic view, and the number of the recessed portions 20a formed is larger than that shown in FIG. 8, and the number of the recessed portions 20a is such that the uneven surface shape 20 can provide an anchor effect. It only has to be done. Specifically, for example, it is preferable to form irregularities such that the surface irregularity shape 20 has a ten-point average roughness (Rz) of about 0.1 to 20 μm, more preferably about 1 to 10 μm. More specifically, for example, it is preferable that the number of the recesses 20a is 1 to 30 μm in diameter and the distance between the centers is 5 to 100 μm.

  As another example (second example) of the shape of the surface concavo-convex shape 20, as shown in FIG. 9, the concave portion 21a has a spiral shape when viewed from above the surface of the groove. FIG. 9 is a schematic view, and the width and the number of turns of the spiral recess 20a may be any number as long as the surface recess / protrusion shape 20 can be provided with an uneven shape capable of providing an anchor effect. The width of 20a is smaller than that shown in FIG. 9, and the number of turns of the spiral recess 20a is larger than that shown in FIG. Specifically, for example, it is preferable to form irregularities such that the surface irregularity shape 20 has a ten-point average roughness (Rz) of about 0.1 to 20 μm, more preferably about 1 to 10 μm.

  As another example (third example) of the shape of the surface concavo-convex shape 20, as shown in FIG. 10, the concave portion 21a is linear when viewed from above the surface of the groove, and the linear concave portion. The thing in which the said recessed part 20a is formed in multiple numbers so that the extending direction of 20a may become parallel is mentioned. Further, FIG. 10 is a schematic view, and the number of the recessed portions 20a formed is larger than that shown in FIG. 10, and the number of the recessed portions 20a is formed so that the surface uneven shape 20 can provide an anchor effect. It only has to be done. Specifically, for example, it is preferable to form irregularities such that the surface irregularity shape 20 has a ten-point average roughness (Rz) of about 0.1 to 20 μm, more preferably about 1 to 10 μm. More specifically, for example, it is preferable that the number of the recesses 20a is 1 to 30 μm and the distance between the centers is 5 to 100 μm.

  As another example (fourth example) of the shape of the surface concavo-convex shape 20, as shown in FIG. 11, two types of recesses are formed, and when viewed from above the surface of the groove, one recess 20b However, it is linear and the other recessed part 20c is circular. A plurality of the linear recesses 20b are formed so that the extending directions of the linear recesses 20b are parallel to each other, and the circular recess 20c has a linear recess with the adjacent linear recess 20b. Plural pieces are formed in a portion between 20 b and 20 b so as to be parallel to the extending direction of the linear recess 20 b. Further, FIG. 11 is a schematic diagram, and the number of the linear recesses 20b formed and the circular recesses 20c are larger than those shown in FIG. It is only necessary that the number or number of irregularities that can provide an effect be formed. Specifically, for example, it is preferable to form irregularities such that the surface irregularity shape 20 has a ten-point average roughness (Rz) of about 0.1 to 20 μm, more preferably about 1 to 10 μm. More specifically, for example, the linear recess 20b has a width of 1 to 30 μm and a center-to-center distance of 5 to 100 μm, and the diameter of the circular recess 20c is as follows. It is preferable that the number is 1 to 30 μm and the distance between the centers is 5 to 100 μm.

  As another example (fifth example) of the shape of the surface irregularity shape 20, as shown in FIG. 12, when the concave portion 21a is viewed from above the surface of the groove, it has a meander shape. FIG. 12 is a schematic diagram, and the width of the concave portion 20a and the distance between the centers of adjacent parallel portions of the concave portion 20a are formed so that the surface uneven shape 20 has an uneven shape capable of providing an anchor effect. The width of the recess 20a and the distance between the centers of adjacent parallel portions of the recess 20a are smaller than those shown in FIG. Specifically, for example, it is preferable to form irregularities such that the surface irregularity shape 20 has a ten-point average roughness (Rz) of about 0.1 to 20 μm, more preferably about 1 to 10 μm. More specifically, for example, it is preferable that the width of the recess 20a is 1 to 30 μm, and the distance between the centers of adjacent parallel portions of the recess 20a is 5 to 100 μm.

  In addition, the plating reinforcement structure as shown in FIG. 3 also uses a laser mold to increase the groove depth of the reinforcing portion, or uses a male mold that increases the groove depth of the reinforcing portion in a mold using embossing. By doing so, it can be easily formed.

  Also, the plating reinforcement structure as shown in FIG. 4 uses a laser processing to provide a protrusion on the circuit outline, or uses a male mold having a protrusion on the outline of the reinforcing portion in a mold using embossing. Can be formed more easily.

  With such a plated reinforcing structure, the formed electric circuit can be partially reinforced.

  The holes provided as necessary in the circuit pattern forming process become via holes or inner via holes for conducting electrical conduction between layers in the electric circuit board by forming plating on the surface in the plating process described later.

  And after forming the circuit pattern 3, you may perform the well-known desmear process using the potassium permanganate solution etc. for the purpose of removing chips.

  Next, as shown in FIG. 1C, the plating catalyst 4 is deposited on the entire surface of the circuit pattern portion 3 formed on the insulating substrate 1 and the entire surface of the resin film 2 covering the insulating substrate 1 (catalyst deposition). Process).

  The plating catalyst 4 is a catalyst applied to form electroless plating only on a portion where the catalyst is activated in a plating process described later, or a precursor thereof, and is known as a catalyst for electroless plating. If there is no particular limitation, it can be used. Specific examples thereof include, for example, metallic palladium (Pd), platinum (Pt), silver (Ag), etc., or precursors that generate these.

Examples of the method for depositing the plating catalyst 4 include the following methods. The insulating substrate 1 on which the circuit pattern 3 is formed is washed with hot water in a surfactant solution for a predetermined time to remove oil and the like adhering to the surface. Next, the insulating substrate 1 is immersed in a stannous chloride aqueous solution having a concentration of about 0.1% to adsorb stannous chloride, and then further immersed in a palladium chloride aqueous solution having a concentration of about 0.01%. To adsorb palladium chloride. Then, metallic palladium is formed by an oxidation-reduction reaction (SnCl ₂ + PdCl ₂ → SnCl ₄ + Pd ↓) between the adsorbed stannous chloride and palladium chloride.

  1C, the plating catalyst 4 is deposited on the surface of the circuit pattern portion 3 formed on the insulating base material 1 and the surface of the resin film 2 covering the insulating base material 1. Is done.

  Next, as shown in FIG. 1D, the resin film 2 is removed by swelling or dissolving with a predetermined liquid (film removal step). According to this step, the plating catalyst 4 can be left only on the surface of the circuit pattern portion 3 by removing the resin film 2.

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

  Next, as shown in FIG. 1E, electroless plating is performed on the insulating substrate 1 from which the film has been removed (plating process). By this step, the electroless plating 5 can be deposited only on the formed circuit pattern portion 3.

  As a method of forming the electroless plating 5, a method of depositing electroless plating only on the circuit pattern portion 3 by immersing the insulating base material 1 after the film removal step in an electroless plating solution may be used.

  Examples of the metal used for electroless plating include Cu (copper), Ni (nickel), Co (cobalt), and Al (aluminum). Among these, plating containing Cu as a main component is preferable from the viewpoint of excellent conductivity, and when Ni is contained, it is preferable from the viewpoint of excellent corrosion resistance and adhesion to solder or the like.

  By such a plating process, the electroless plating 5 is deposited only on the circuit pattern portion 3 obtained by forming the groove and / or the hole having the desired shape and depth formed in the insulating substrate 1. be able to. Thereby, the electric circuit 10 is formed on the insulating substrate 1.

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

  According to the method for manufacturing an electric circuit described above, even when an electric circuit having a narrow line width and line interval is formed, the surface is partially provided with a concavo-convex shape or a deep groove is partially formed. By doing so, it is possible to reinforce the metal wiring in the easily damaged part. Further, since the electric circuit to be formed is formed by depositing the plating catalyst only on the portion where the metal wiring is to be formed, a circuit with high shape accuracy can be obtained. By using such an electric circuit manufacturing method, the wiring width and the wiring interval are narrow, and it is suitable for applications such as an IC substrate, a printed wiring board for a mobile phone, a three-dimensional wiring board, etc. The single-sided, double-sided, multi-layered type electric circuit board used can be manufactured.

DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Resin film 3 Circuit pattern part 3a Plating reinforcement structure 4,102 Plating catalyst 5 Electroless plating 10 Electrical circuit 20 Surface uneven | corrugated shape 21 Land part 22 Circuit line part 30 Plating reinforcement structure 31 and 41 land part from which thickness differs 32, 42 Circuit line part 40 Projection part 50 Male mold 100 Insulating base material 101 Through hole 103 Photoresist layer 104 Metal wiring 105 Unnecessary plating part 110 Photomask

Claims (6)

A film forming step of forming a resin film on the surface of the insulating substrate, and grooves and / or holes having a desired shape and depth by laser processing or machining the insulating substrate from the outer surface side of the resin film. Forming a circuit pattern portion to form a circuit pattern portion; and a catalyst coating for depositing a plating catalyst or a precursor thereof on the surface of the circuit pattern portion of the insulating substrate and the surface of the resin film covering the insulating substrate. An adhesion process, a film peeling process for peeling the resin film from the insulating base material, and a plating process step for performing electroless plating on the insulating base material from which the resin film has been peeled,
In the circuit pattern forming step, a plating reinforcing structure is formed on at least a part of the circuit pattern portion.   The method of manufacturing an electric circuit according to claim 1, wherein the plating reinforcement structure is formed by providing an uneven shape on a surface of the groove.   The circuit pattern portion has at least one land portion for surface-mounting an electronic component and a circuit line portion formed integrally with the land portion, and the uneven shape is imparted to the surface of the land portion. Item 3. A method for manufacturing an electric circuit according to Item 2.   The circuit pattern portion has at least one land portion for surface mounting an electronic component and a circuit line portion formed integrally with the land portion, and the plating reinforcement structure has a groove depth of the land portion. The method of manufacturing an electric circuit according to any one of claims 1 to 3, wherein the circuit line portion is formed so as to be deeper than a groove depth of the circuit line portion.   The circuit pattern part has at least one land part for surface mounting an electronic component and a circuit line part formed integrally with the land part, and the plating reinforcement structure is provided on the outer periphery of the groove of the land part. The method for manufacturing an electric circuit according to claim 1, wherein the electric circuit is formed by providing at least one protrusion.   An electric circuit board provided with the electric circuit obtained by the manufacturing method of any one of Claims 1-5.

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