TW201304634A - Circuit board production method, and circuit board obtained by production method - Google Patents

Abstract

Provided is a production method for a circuit board, that includes a step for forming a circuit pattern in a resist formed on the surface of an insulating substrate, wherein the production method involves forming a resin coating of uniform thickness on the surface of an asperate structure, and reduces material loss, as a result obtaining an exceptional circuit board of extremely high reliability. The provided production method for a circuit board includes a resist formation step in which a resin coating is formed on the surface of an insulating substrate, and a circuit formation step in which, using the outer surface of the resin coating as a reference, recessed portions of a depth at least equal to the resin coating thickness are formed to form a circuit pattern; wherein the production method for a circuit board involves formation of the resin coating by electrostatic atomization.

Description

Method for manufacturing circuit substrate, and circuit substrate obtained by the same Field of invention

The present invention relates to a method of manufacturing a circuit board and a circuit board obtained by the method.

Background of the invention

In recent years, the electric circuit of the electric field and the electric field has become denser, and the wiring is thinner and thinner, and the wiring interval is narrowing. However, the narrower the wiring interval, the more likely the short circuit and migration occur between adjacent wirings.

In order to cope with this problem, Patent Document 1 describes a method of manufacturing a circuit board as described below. First, a resin film (photoresist) is formed on the surface of the insulating substrate. Next, a recessed portion having a thickness equal to or greater than the thickness of the resin film is formed on the basis of the outer surface of the resin film to form a circuit pattern. Next, the surface of the circuit pattern and the surface of the resin film are coated with a plating catalyst or a precursor thereof. Next, the resin film is removed from the insulating substrate. Next, an electroless plating film is formed only at a portion where the plating catalyst or its precursor remains after the resin film is removed. According to such a manufacturing method, a high-precision electrical circuit can be formed on the insulating base material, and a circuit board that suppresses occurrence of short-circuit and migration can be obtained.

On the other hand, in the method of manufacturing such a circuit board, it is very important to form a resin film (film forming property) in a uniform thickness and to form a film (film forming property).

As far as the wiring formation on the planar body is known, it is known to be used. The method of forming the resin film is a method using a spin coating method (for example, Patent Document 2) and a dry film (for example, Patent Document 3).

Advanced technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2010-135768

Patent Document 2: Japanese Patent Laid-Open No. 2011-44722

Patent Document 3: Japanese Patent Laid-Open Publication No. 2005-266347

Summary of invention

However, although the spin coating method can form a certain degree of film, on the other hand, there are problems such as large material loss and difficulty in surface enlargement. Further, in the case of the three-dimensional circuit formation, even when the spin coating is applied, it is difficult to form a resin film layer having a uniform thickness on the surface of the uneven structure even if the viscosity of the liquid to be applied and the adjustment of the spin coating conditions are adjusted.

Further, when the convex apex portion of the structure is to be thick, it is considered to increase the viscosity of the resin liquid or to reduce the number of spin coating rotations, but in this case, liquid stagnation occurs at the lower edge portion of the convex structure. The problem. When there is a liquid stagnation, the photoresist is not removed and remains in the laser processing, so that only the portion of the circuit is not formed (open circuit), resulting in loss of function as an electrical circuit.

On the other hand, in order to prevent the liquid from stagnation, the method of reducing the viscosity of the liquid or increasing the number of rotations of the spin coating may be considered. However, in this case, the thickness of the apex portion of the convex body structure becomes extremely thin, depending on the situation. There will be no resin film formed, resulting in excessive plating (circuit short circuit) in many places, resulting in loss of work It is a function of an electrical circuit.

Furthermore, although it is also considered to use a spray coater (or a curtain coater), in this case, it is difficult to control the formation of the film, and the thickness unevenness is large due to the large particle size that is blown, which is difficult. The film is uniformly formed on the planar body and the uneven structure.

Even if a dry film method is used, it is costly to dry the film, and it is difficult to trace the uneven shape, and this is not applicable to the formation of the resin film of the uneven structure.

The present invention has been made in view of the above circumstances, and in order to solve the above problems, a resin film having a uniform thickness is formed on the surface of the uneven structure by using the resin film forming method described above, and the material loss is reduced, and as a result, the reliability is extremely high. High excellent circuit substrate.

The present inventors have intensively studied in order to solve the above problems, and as a result, have found that the above problems can be solved by the following means.

The method for manufacturing a circuit board according to a layout of the present invention includes: a step of forming a photoresist on a surface of an insulating substrate; and forming a thickness greater than a thickness of the resin film based on an outer surface of the resin film; A circuit forming step of forming a circuit pattern by the recess; and the resin film is formed by electrostatic spraying.

Furthermore, the circuit board of another layout of the present invention is manufactured by the above-described manufacturing method.

According to the present invention, in the formation of the resin film of the method for manufacturing a circuit board, the material is not wasted, and a resin film having a uniform thickness can be formed on the surface of the uneven structure body, and high reliability can be obtained with high productivity. Different circuit substrate.

Simple illustration

The first (A) to (E) drawings are process diagrams of a method of manufacturing a circuit board according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a state in which a plane is electrostatically sprayed.

Fig. 3 is a schematic view showing a state in which a three-dimensional surface is electrostatically sprayed.

Fig. 4 is a view showing the measurement point of the resin film thickness of the examples.

Form for implementing the invention

The method of manufacturing a circuit board according to the present embodiment includes a step of forming a photoresist on a surface of an insulating substrate, and forming a concave portion having a thickness equal to or greater than a thickness of the resin film based on an outer surface of the resin film. A circuit forming step of the circuit pattern; wherein the resin film is formed by electrostatic spraying.

The method of manufacturing the circuit board of the present embodiment has the above-described configuration, and the other steps are not particularly limited. Hereinafter, one of the embodiments will be specifically described using the first embodiment. In addition, the symbol of each element in the first figure and the second figure is as follows: 1. Insulation substrate, 2. Resin film (resistance), 3. Circuit groove (concave portion (circuit pattern)), 4. Through hole (recessed portion (circuit pattern)), 5. electroplating catalyst, 6. electrical circuit (electroless plating film), 10. circuit substrate, 11. nozzle.

First, as shown in FIG. 1, the method of manufacturing the circuit board 10 of the present embodiment includes a photoresist forming step (A), a circuit forming step (B), a catalyst coating step (C), and a film removing step ( D), and plating treatment step (E). The The photoresist forming step (A) forms a resin film (photoresist) 2 on the surface of the insulating base material 1. In the circuit forming step (B), the concave portions 3 and 4 having a thickness equal to or greater than the thickness component of the resin film 2 are formed by laser processing on the basis of the outer surface of the resin film 2 to form a circuit pattern. In the catalyst coating step (C), the plating catalyst 5 or its precursor is coated on the surface of the circuit pattern and the surface of the resin film 2. This film removing step (D) removes the resin film 2 from the insulating substrate 1. In the plating treatment step (E), the electroless plating film 6 is formed only at a portion where the plating catalyst 5 or its precursor remains after the resin film 2 is removed.

Then, as shown in Fig. 1(A), the photoresist forming step forms the resin film 2 on the surface of the insulating substrate 1.

Next, as shown in Fig. 1(B), the circuit forming step forms a circuit pattern by laser processing to form recesses 3 and 4 having a thickness equal to or greater than the thickness component of the resin film 2 based on the outer surface of the resin film 2. . The circuit pattern may be a recess reaching the surface of the insulating substrate 1, but from the viewpoint that the electrical circuit 6 obtained last is not easily detached, it is preferable to cut into the concave portion of the insulating substrate 1 as shown. .

In the figure, the component symbol 3 is a circuit groove constituting a circuit pattern, and the component symbol 4 is a through hole constituting the same circuit pattern. By using the circuit grooves 3 and the through holes 4, the portion where the electroless plating film 6 (i.e., the electric circuit) is formed is standardized. Hereinafter, the circuit pattern will be described mainly on the circuit groove 3, but the state of the through hole 4 is also the same.

Next, as shown in FIG. 1(C), in the catalyst coating step, the surface of the circuit trench 3 and the surface of the resin film 2 on which the circuit trench 3 is not formed are coated with the plating catalyst 5 or its precursor. .

Next, as shown in Fig. 1(D), in the film removing step, the resin film 2 is removed from the insulating base material 1. As a result, in the surface of the insulating base material 1, the plating catalyst 5 or its precursor remains on only the surface of the portion where the circuit groove 3 is formed. On the other hand, the plating catalyst 5 or its precursor coated on the surface of the resin film 2 is removed together with the resin film 2 in a state of being carried on the resin film 2.

Then, as shown in Fig. 1(E), in the plating treatment step, the insulating substrate 1 from which the resin film 2 has been removed is subjected to electroless plating. As a result, the electroless plating film 6 is formed only at the portion where the plating catalyst 5 or its precursor remains. That is, an electroless plating film to be the electrical circuit 6 is formed at a portion where the circuit trench 3 is formed. The electrical circuit 6 may be formed only of an electroless plating film, or may be further subjected to electroless plating (filling plating) to the electroless plating film, and the plating film may be further thickened. For example, the electric circuit 6 made of an electroless plating film may be formed so that the buried circuit groove 3 and the through hole 4 as a whole are removed, and the height difference between the insulating base material 1 and the electric circuit 6 may be released.

The circuit board 10 as shown in Fig. 1(E) is obtained in accordance with the above steps (A) to (E). This circuit board 10 forms a highly accurate electrical circuit 6 on the insulating base material 1, and the occurrence of short circuit and migration is suppressed.

Hereinafter, in the above-described respective steps, the film formation method of the material and the resin film will be specifically described in detail.

<Insulation substrate>

The insulating base material 1 is not particularly limited as long as it can be used for the production of a circuit board. For example, a resin substrate containing a resin or the like.

The resin substrate is removed before various organic substrates which can be used for the production of a circuit board (for example, a multilayer circuit board), and the rest can be used without particular limitation. Specific examples of the organic substrate are used in the manufacture of a multilayer circuit substrate, for example, an epoxy resin, an acrylic resin, a polycarbonate resin, a polyimide resin, a polyphenylene sulfide resin, a polyphenylene ether resin, Cyanate resin, benzo A substrate composed of a resin, a bis-butenylene imine resin, or the like.

The epoxy resin is used in various organic substrates which can be used for the production of a circuit board, and is not particularly limited as long as it belongs to the epoxy resin constituting the organic substrate. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, aralkyl epoxy resin, phenol novolac epoxy resin, alkylphenol novolac epoxy resin, Bisphenol type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, epoxide of phenol and condensate of phenolic hydroxyl group aromatic aldehyde, iso-trisocyanate Ester, alicyclic epoxy resin, etc. Further, in order to impart flame retardancy, for example, an epoxy resin modified with bromination or phosphorus, a resin containing nitrogen, a resin containing polyoxymethylene or the like may be used. These resins may be used singly or in combination of two or more.

When the base material is composed of each resin, it is generally hardened to contain a curing agent. The hardener is removed before it can be used as a hardener, and the rest is not particularly limited. For example: dicyandiamide, phenolic hardener, acid anhydride hardener, amine base three A phenolic curing agent, a cyanate resin, or the like. The phenolic curing agent may be, for example, a novolac type, an aralkyl type, a terpene type or the like. Further, in order to impart flame retardancy, for example, a phosphorus-modified phenol resin or a phosphorus-modified cyanate resin may be used. These hardeners may be used alone or in combination of two or more.

In addition, although the circuit pattern is formed by laser processing in the circuit forming step (B), it is preferable to use a resin having a high laser light absorption rate in a wavelength region of, for example, 100 to 400 nm. For example, polyimine resin or the like.

The insulating substrate 1 may also 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 in the laser processing portion, and the adhesion between the plating and the resin is obtained by the unevenness of the exposed filler.

The material constituting the inorganic fine particles may be, for example, alumina (Al ₂ O ₃ ), magnesium oxide (MgO), boron nitride (BN), aluminum nitride (AlN), cerium oxide (SiO ₂ ), barium titanate ( High dielectric constant filler such as BaTiO ₃ ), titanium oxide (TiO ₂ ), magnetic filler such as hard ferrite iron, magnesium hydroxide (Mg(OH) ₂ ), aluminum hydroxide (Al(OH) ₂ ), three Inorganic flame retardant such as antimony oxide (Sb ₂ O ₃ ), antimony pentoxide (Sb ₂ O ₅ ), antimony salt, zinc borate, molybdenum compound, zinc stannate, etc.; talc (Mg ₃ (Si ₄ O ₁₀ ) (OH ₂ ), barium sulfate (BaSO ₄ ), calcium carbonate (CaCO ₃ ), mica, and the like. These inorganic fine particles may be used singly or in combination of two or more. Since the inorganic fine particles have high thermal conductivity, relative dielectric constant, flame retardancy, particle size distribution, color tone degree, and the like, when the selectivity is exerted as desired, by appropriate blending and particle size design, High filling is easy. Further, although it is not particularly limited, it is preferably a filler having an average particle diameter of the insulating base material 1 or less, and for example, a filler having an average particle diameter of 0.01 to 10 μm, preferably 0.05 μm to 5 μm, is used.

In order to improve the dispersibility of the inorganic fine particles in the insulating substrate 1, the inorganic fine particles may be subjected to surface treatment using a decane coupling agent, or may be used in the insulating substrate 1. Blended with a decane coupling agent. The decane coupling agent is not particularly limited. For example, an epoxy decane type, a thiol decane type, an amino decane type, a vinyl decane type, a styryl decane type, a methacryloxy decane type, a propylene methoxy decane type, a titanate type, etc. Decane coupling agent and the like. These decane coupling agents may be used alone or in combination of two or more.

Further, in order to improve the dispersibility of the inorganic fine particles in the insulating base material 1, a dispersing agent may be blended in the insulating base material 1. The dispersant is not particularly limited. For example, an alkyl ether system, a sorbitan ester system, an alkyl polyether amine system, a dispersing agent such as a polymer system, and the like. These dispersing agents may be used alone or in combination of two or more.

<Resin film>

The resin film 2 is a photoresist that allows the plating catalyst 5 or its precursor to be coated only and remains in the laser-processed portion. The resin film 2 is a photoresist which can be formed by electrostatic spraying described later, and is not removed in the catalyst coating step (C), but may be removed in the film removing step (D), and the rest may be No special restrictions.

For example, a soluble resin which can be easily dissolved by using an organic solvent or an alkali solution, or a swellable resin film made of a resin which can be swollen by a swelling liquid (for example, an alkaline solution used in a film removal step) described later.

In addition, since the resin used for the resin film is formed by photoresist by electrostatic spraying described later, it is preferable to contain at least one type of solvent having a dielectric property of a dielectric constant of 2 or more. When the relative dielectric constant is 2 or more, electrostatic spraying can be performed without any problem, and a solvent having a relative dielectric constant of 4 or more, more preferably 8 or more is preferably used.

Further, the resin used in the resin film of the present embodiment preferably has a viscosity of 400 mPas or less. When the resin viscosity is 400 mPas or less, electrostatic spraying can be performed without any problem, and a resin having a viscosity of 200 mPas or less, more preferably 100 mPas or less is preferably used. The viscosity of such a resin can be adjusted according to the kind and amount of the solvent blended in the resin. Further, in the present embodiment, the viscosity is measured under conditions of 25 °C.

If the relative dielectric constant of the solvent is lower than the above or the resin viscosity is higher than the above, there is a possibility that the spraying will not be performed in the electrostatic spray, and the formation of the film may not be performed.

The thickness of the resin film 2 is preferably 5 μm or less, more preferably 3 μm or less. Further, the thickness of the resin film 2 is preferably 0.1 μm or more, more preferably 0.5 μm or more, and particularly preferably 1 μm or more. When the thickness of the resin film 2 is too large, the circuit pattern 3 formed by laser processing in the circuit forming step (B), the precision of the circuit pattern such as the through hole 4, or the like, or the resin film 2 having a uniform film thickness is difficult to form. Propensity. When the thickness of the resin film is too thin, when the plating catalyst 5 or its precursor is coated, the resin film 2 may be peeled off, and plating may be formed at an unnecessary portion.

In the present embodiment, the resin film 2 (photoresist) preferably has excellent properties such as laser processability, acid resistance, and alkali peelability. In the present embodiment, from this viewpoint, it is preferable to use a polymer component in which the photoresist 2 is composed of the following copolymer. The copolymerization system is composed of (i) a monomer containing a monomer unit having at least one carboxyl group, and (ii) a monomer copolymerizable with the monomer and having an unsaturated bond at a molecular terminal.

In the present embodiment, the laser processing property of the resin film 2 is considered to be an example. Such as to improve the adhesion of the resin film 2 to the insulating base material 1, and the polymer is likely to cause molecular cutting or the like.

In the present embodiment, the acid resistance of the resin film 2 is considered to be improved by, for example, improving the adhesion of the resin film 2 to the insulating base material 1 and having an acidic functional group to the polymer.

In the present embodiment, the alkali peelability of the resin film 2 is considered to be improved by, for example, a polymer having an acidic functional group, a polymer having an alkali solubility, and a polymer having a bulky functional group.

In the present embodiment, the polymer preferably contains 10 to 90% by mass of the α,β-unsaturated carbonyl group-containing monomer as the monomer (i), and as the monomer (ii). A copolymer of at least a binary system or more, which is copolymerizable with the monomer (i) and having a polymerizable unsaturated group at a molecular terminal, in an amount of from 10 to 90% by mass. The polymer having such a configuration can provide the resin film 2 excellent in laser workability, acid resistance, alkali peelability, and the like.

In the above polymer, the α,β-unsaturated carbonyl group-containing monomer (i) is preferably selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and the like. At least one of the constituent groups is selected. The laser processability, acid resistance, and alkali peelability of the obtained polymer will become more favorable.

In the above polymer, the monomer (ii) having a polymerizable unsaturated group at the molecular terminal is preferably at least one selected from the group consisting of styrene and a compound having a diene skeleton. The laser processability, acid resistance, and alkali peelability of the obtained polymer will become more favorable.

In the above polymer, the weight average molecular weight of the polymer is preferably from 5,000 to 1,000,000. Because the weight average molecular weight of the polymer is 1,000,000 or less, thus ensuring good peelability of the photoresist. Since the weight average molecular weight of the polymer is 5,000 or more, good acid resistance of the photoresist can be ensured.

One of the specific examples of the polymer having the above constitution is a ternary copolymerized polymer of, for example, an acrylic acid-styrene-alkyl acrylate. The polymer is a random copolymer. The ternary blending ratio may be, for example, 27% by mass of acrylic acid, 555% by mass of styrene, and 18% by mass of alkyl acrylate. The alkyl acrylate may be, for example, 2-ethylhexyl acrylate.

Further, the resin film 2 may contain a filler. The filler is not particularly limited, and specifically, for example, cerium oxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, clay, kaolin, titanium oxide, barium sulfate, aluminum oxide, zinc oxide, talc, mica, glass, titanium Potassium acid, strontium stone, magnesium sulfate, aluminum borate, organic filler, and the like. Further, the thickness of the photoresist is generally as thin as 1 to 10 μm, and therefore it is preferable that the size of the filler is also small. It is possible to use a smaller average particle size or a coarse-grained cut, and the coarse particles can be removed by pulverization and filtration during dispersion.

Other additives may be, for example, a photopolymerizable resin (photopolymerization initiator), a polymerization terminator, a colorant (dye, pigment, chromonic pigment), a thermal polymerization initiator, an epoxy, and a urethane. Joint agent and so on.

In the printing substrate processing process of the present invention, for example, laser processing is used, and in the case of performing laser processing, it is necessary to impart erosion resistance due to laser irradiation to the resin film material. Laser processing machines are selected, for example, from carbonated gas lasers, excimer lasers, UV-YAG lasers, and the like. These laser processing machines have various characteristic wavelengths, and productivity can be improved by setting a material having a high absorption rate for the wavelength. Among them, UV-YAG laser is suitable for fine processing because of laser light The base wavelength is 1064 nm, the third harmonic is 355 nm, and the fourth harmonic is 266 nm. Therefore, the resin film material preferably has a high absorption rate for the wavelengths. On the other hand, there is also a case where a material having a low absorption rate is preferable. Specifically, for example, if a resin film having a low UV absorption rate is used, since UV light penetrates the resin film, energy can be concentrated on the insulating layer processing of the underlayer. That is, according to the absorption rate of the laser light, the advantages are different, and therefore, the resin film of the laser light absorption rate of the adjusted resin film can also be used.

In the present embodiment, the resin film 2 is obtained by forming a liquid material in which the polymer (and other additives as needed) are blended in a solvent. As such a solvent, as described above, it is preferred to use at least one solvent containing at least one solvent having a dielectric constant of 2 or more. In addition, the resin used in the resin film is preferably from 400 mPas or less from the viewpoint of facilitating electrostatic spraying. Therefore, it is preferable to appropriately adjust the type and amount of the solvent to be blended in the resin so that the resin viscosity is 400 mPas or less. .

More specifically, examples of the solvent which can be used in the embodiment include hexane, benzene, toluene, diethyl ether, chloroform, ethyl acetate, tetrahydrofuran, dichloromethane, acetone, acetonitrile, and N,N-dimethyl. Base formaldehyde, dimethyl hydrazine, 1-butanol, 2-propanol, 1-propanol, ethanol, methanol, formic acid, water, and the like.

In addition, in the embodiment in which the viscosity of the resin is 400 mPas or less, the polymer can be used, for example, after forming a solution of an organic solvent (IPA or the like) having a solid content of 10 to 30%.

In the present embodiment, the resin film 2 is applied to the surface of the insulating base material 1, and a liquid material capable of forming the resin film 2 as described above is applied by electrostatic spraying. After the material is formed, it is dried.

In the present embodiment, the electrostatic spray method used to form the resin film is a method of forming a film by atomizing the spray particle diameter from a very fine nozzle by using a static electrode as shown in FIGS. 2 and 3 and the like. As shown in Fig. 2, the liquid material ejected from the nozzle 11 breaks the surface tension of the split liquid surface by electrostatic force, and the molecules repel each other, so that the resin film 2 is formed on the substrate 1 without agglomeration. In the second embodiment, the planar substrate 1 is subjected to electrostatic spraying. However, even if electrostatic spraying is applied to the three-dimensional surface substrate 1 as shown in Fig. 3, the liquid material does not aggregate and a uniform resin film is formed on the substrate. 2.

In addition, the electrostatic spray system can be used, for example, by a commercially available device, and a specific example can be an electrostatic spray device ("ZZ114-1") manufactured by Yamada Advanced Technology Co., Ltd., or the like.

<Circuit forming step>

The circuit forming step is a step of forming a circuit pattern such as the circuit groove 3 on the insulating substrate 1. As described above, the circuit pattern may not only reach the circuit groove 3, but also may be a recessed portion where the resin film 2 reaches the surface of the insulating base material 1, or may be a through hole 4.

The method of forming the aforementioned circuit pattern is not particularly limited. Specifically, for example, on the insulating substrate 1 on which the resin film 2 has been formed, a machine such as a laser processing or a cutting process or a die-casting process can be performed from the outer surface side of the resin film 2 A method or the like for forming the circuit groove 3 of a desired shape and depth by processing or the like. When forming a highly accurate and fine circuit, it is preferable to use laser processing. If using laser processing, by making The laser output can be adjusted freely by changing the output of the laser. Further, the press molding is preferably carried out by, for example, compression molding using a fine resin mold in the field of nanoimprinting.

In the case of laser processing, UV-YAG lasers are preferably used for fine processing, with a laser based wavelength of 1064 nm, a third harmonic of 355 nm, and a fourth harmonic of 266 nm.

A part of the circuit groove 3 may also form a through hole 4 for forming a via hole or the like.

By this step, the shape and depth of the circuit groove 3, and the shape of the circuit pattern such as the diameter and position of the through hole 4 are specified. The circuit forming step can be performed by digging the thickness of the resin film 2 or more, and the thickness component of the resin film 2 can be dug, and the thickness component of the resin film 2 can be excavated.

The width of the circuit pattern such as the circuit groove 3 formed by the circuit forming step is not particularly limited. Further, in the case of laser processing, a fine circuit such as a line width of 20 μm or less can be easily formed. Further, the depth of the circuit trench is the depth of the electrical circuit formed in the present embodiment when the height difference between the electrical circuit and the insulating substrate is removed by filling the plating.

<Catalyst Covering Step>

The catalyst coating step is a step of coating the surface of the circuit pattern such as the circuit groove 3 and the surface of the resin film 2 with the plating catalyst 5 or its precursor. At this time, in the case where the through hole 4 is formed, the plating catalyst or its precursor is also coated on the inner wall surface of the through hole 4.

The plating catalyst 5 or its precursor system is formed in the plating treatment step in order to impart a portion to be formed only by electroless plating to form an electroless plating film. Catalyst for electroless plating film. The plating catalyst is provided before being known as a catalyst for electroless plating, and the rest is not particularly limited. Further, the precursor coated with the plating catalyst may be removed in advance to remove the resin film, and then the plating catalyst may be formed. Specific examples of the plating catalyst may be, for example, metal palladium (Pd), platinum (Pt), silver (Ag), or the like, or formation of such precursors and the like.

The method of coating the plating catalyst 5 or its precursor can be, for example, a treatment using an acidic Pd-Sn colloid solution treated under acidic conditions of pH 1-3, followed by treatment with an acid solution. Specifically, it can be, for example, the following method.

First, the oil or the like adhering to the surface of the insulating base material 1 on which the circuit groove 3 and the through hole 4 have been formed is subjected to hot water washing for a predetermined period of time in the solution (cleaning and adjustment) of the surfactant. Next, a soft etching treatment is performed using a sodium persulfate-sulfuric acid soft etchant as needed. Then, pickling is carried out in an acidic solution such as an aqueous sulfuric acid solution or a hydrochloric acid aqueous solution such as pH 1-2. Next, it is immersed in a prepreg containing, for example, a stannous chloride aqueous solution having a concentration of about 0.1% as a main component, and a prepreg treatment in which chloride ions are adhered to the surface of the insulating base material 1 is applied. Then, by further immersing in an acidic plating catalyst colloidal solution such as an acidic Pd-Sn colloid containing stannous chloride and palladium chloride and having a pH of 1-3, Pd and Sn are aggregated and adsorbed. Then, a redox reaction (SnCl ₂ + PdCl ₂ → SnCl ₄ + Pd ↓) is initiated between the adsorbed stannous chloride and palladium chloride. Thereby, metal palladium which is an electroplating catalyst is precipitated.

Further, as the acidic plating catalyst colloidal solution, a known acidic Pd-Sn colloidal catalyst solution or the like may be used, or a commercially available electroplating process using an acidic plating catalyst colloidal solution may be employed. This type of process has been made by, for example, Robm and Haas Submaterials Co., Ltd. is systematic and sold.

By the catalyst coating treatment, the plating catalyst 5 or its precursor can be coated on the surface of the circuit groove 3, the inner wall surface of the through hole 4, and the surface of the resin film 2.

<film removal step>

The film removing step is a step of removing the resin film 2 from the insulating base material 1 on which the catalyst coating step has been carried out.

The method of removing the resin film 2 is not particularly limited. Specifically, for example, a method in which the resin film 2 is swelled by using a predetermined solution (swelling liquid), and then the resin film 2 is peeled off from the insulating base material 1; the resin film 2 is swelled by a predetermined solution (swelling liquid) Further, after partially dissolving a part thereof, a method of peeling the resin film 2 from the insulating base material 1 and a method of dissolving and removing the resin film 2 by a predetermined solution (swelling liquid) are used. The swelling liquid is not particularly limited as long as the resin film 2 can be swollen. In addition, the insulating base material 1 which has been covered by the resin film 2 is immersed or dissolved in the swelling liquid for a predetermined period of time. However, in this immersion, the removal efficiency can also be improved by performing ultrasonic irradiation. In addition, when swelling and peeling, it is also possible to use a light pull.

In addition, the resin film 2 is described with respect to the case where the above-mentioned swellable resin film is used.

When the liquid (swelling liquid) which swells the swelling resin film 2 is not decomposed or dissolved in the insulating base material 1 and the plating catalyst 5 or its precursor, the swellable resin can be obtained. Film 2 swelling or dissolving The liquid is taken up beforehand, and the rest can be used without particular limitation. Further, it is preferable that the swellable resin film 2 is swollen to a liquid which can be easily peeled off. Such a swelling liquid can be appropriately selected depending on the type and thickness of the swellable resin film 2. Specifically, for example, when the swellable resin film is an elastomer such as a diene-based elastomer, an acrylic elastomer, or a polyester-based elastomer, or contains at least one polymerizable property in the molecule (a). a polymer resin obtained by polymerizing at least one of a carboxylic acid or an acid anhydride having a saturated group and at least one monomer capable of polymerizing the monomer (a), or a polymer resin In the case where the resin composition or the carboxyl group-containing acrylic resin is formed, it is preferable to use an aqueous alkali solution such as a sodium hydroxide aqueous solution having a concentration of, for example, about 1 to 10%.

Further, in the catalyst coating step, when the electroplating process is carried out in accordance with the acidic conditions as described above, the swellable resin film 2 preferably has a degree of swelling under acidic conditions of less than 50%, preferably 40% or less. And the degree of swelling under alkaline conditions is 50% or more, such as an elastomer such as a diene elastomer, an acrylic elastomer, and a polyester elastomer; or (a) having at least 1 in the molecule a polymer resin obtained by polymerizing at least one of a polymerizable unsaturated group carboxylic acid or an acid anhydride and (b) at least one monomer capable of polymerizing the monomer (a) or A resin composition containing the above polymer resin or a carboxyl group-containing acrylic resin is formed. Such a swellable resin film can be easily swollen and peeled off by using an aqueous alkali solution having a pH of 12 to 14, for example, a sodium hydroxide aqueous solution having a concentration of about 1 to 10%. Further, in order to improve the peeling property, ultrasonic irradiation may be performed during the immersion. Moreover, it can also be peeled off by using a light force peeling as needed.

The method of swelling the swellable resin film 2 is, for example, a method in which the insulating base material 1 coated with the swellable resin film 2 is immersed in the swelling liquid for a predetermined period of time. Further, in order to improve the peeling property, it is more preferable to perform ultrasonic irradiation in the immersion. In addition, when it is only dependent on swelling and cannot be peeled off, it is also possible to use light force peeling as needed.

<plating process step>

The plating treatment step is a step of performing an electroless plating treatment on the insulating base material 1 after the removal of the resin film 2.

The electroless plating treatment method may be performed by immersing the insulating substrate 1 partially coated with the plating catalyst 5 or its precursor in an electroless plating solution so that only the plating catalyst 5 or its precursor is used. A method of depositing an electroless plating film (electroplating layer) at a portion where the coating is applied.

The metal used for electroless plating may be, for example, copper (Cu), nickel (Ni), cobalt (Co), aluminum (Al) or the like. Among these, from the viewpoint of excellent electrical conductivity, electroplating using Cu as a main component is preferred. Further, in the case where Ni is contained, it is preferable from the viewpoint of excellent corrosion resistance and adhesion to solder.

The film thickness of the electroless plated film 6 is not particularly limited. Specifically, it is preferably, for example, 0.1 to 10 μm, more preferably about 1 to 5 μm. In particular, by deepening the depth of the circuit trench 3, a thick metal plating can be formed, and a metal wiring having a large cross-sectional area can be easily formed. In this case, it is preferable from the viewpoint of improving the strength of the metal wiring.

By the plating treatment step, the electroless plating film is deposited only on the portion of the surface of the insulating substrate 1 where the plating catalyst 5 or its precursor remains. Therefore, it is possible to form the conductive layer only at the portion where the circuit pattern portion is to be formed. another On the other hand, it is possible to suppress the precipitation of the electroless plated film at the portion where the circuit pattern portion is not formed. Therefore, even in the case where a plurality of fine circuits having narrow pitches and narrow line widths form a plurality of strips, unnecessary plating films are not left between adjacent circuits. Therefore, occurrence of a short circuit and migration can be suppressed.

[Examples]

Hereinafter, the present invention will be more specifically described by way of examples. In addition, the scope of the invention is not to be construed as being limited by the following examples.

(Test Example 1: Formation of a flat resin film)

First, a test piece (insulating base material: developed by our company) whose surface is as flat as possible is used, and one side of each test piece is used: electrostatic spray method (manufactured by Yamada Advanced Technology Co., Ltd., electrostatic spray device "ZZ114" -1") (Example 1), spin coating method (manufactured by Mikasa Co., Ltd., 1H-2D, rotation speed: 300 rpm - 20 sec + 3000 rpm - 20 sec) (Comparative Example 1), spray coating method (Yamanaka Semiconductor Co., Ltd.) (Comparative Example 2) and dry film (Comparative Example 3), the resin film formation property to the flat surface was confirmed.

Further, the resin film material is a ternary copolymerized polymer containing styrene-styrene--2-ethylhexyl acrylate (mixing ratio: 27% by mass of acrylic acid, 55% by mass of styrene, 2-ethyl acrylate) A resin composition for a photoresist of 18% by mass of hexyl hexyl ester. Further, the solvent of the resist resin composition was isopropyl alcohol (relative dielectric constant 18) to form a solution having a viscosity of 10 mPas and a solid content of 10%. In the related dry film (Comparative Example 3), a dry film formed by applying and drying the PET film on the PET film was used.

The uniformity film property and film formability were evaluated, and the test piece after the resin film formation was observed by the cross section was evaluated.

Corresponding laser processing is performed after the resin film is formed, and after performing groove processing using a UV-YAG laser (5370 machine manufactured by ESI Corporation) (laser light wavelength: 355 nm), a digital microscope (KH- manufactured by Hirox Co., Ltd.) is used. 7700) Check if there is any processing failure.

The relevant assessment benchmarks are as follows.

Uniform film formation

Judging from the cross section of the film-forming sample. If the film-forming surface is flat, it is rated as "◎", and if it is not flat, it is rated as "X".

2. Film formability

Judging from the cross section of the film-forming sample. If a film having a thickness of 3 μm or less is formed, it is rated as "◎", and if it is 3 to 5 μm, it is rated as "○", and if it is 5 μm or more, it is rated as "X".

3. Laser processing is poor

The film-forming sample was subjected to groove processing using a UV-YAG laser. After the processing, the case where the resin film adhered to the groove portion was 0 was evaluated as "◎", and the case where 1 or 2 was evaluated was evaluated as "△". "," will be rated as "X" in three or more cases.

The results are shown in Table 1.

As is apparent from Table 1, when the electrostatic spray and the spin coating were used, the uniform film formation property, the film formation property, and the laser processing failure were all good. In the case of a dry film, it was found that although the film forming property was high, it was difficult to form a film of 5 μm or less.

Furthermore, if the electrostatic spray is compared with the spin coating, the electrostatic spray only sprays the material where it is not formed. In contrast, since the spin coating is blown and the excess material is removed, the film is formed, so that it is compared to the electrostatic spray. Underneath, material losses become very much. Therefore, it is considered that it is preferable to use an electrostatic spray for the formation of a flat resin film.

(Test Example 2: Formation of a three-dimensional resin film)

Next, the formation of a three-dimensional resin film is reviewed. A test piece (insulating base material: developed product of the company) having a projection of 60 μm on the upper side, 180 μm on the lower side, 100 μm in height, and 1 mm in length was produced. For the surface of each test piece, an electrostatic spray method (ZZ114-1 manufactured by Yamada Advanced Technology Co., Ltd.) (Example 2), a spin coating method (manufactured by Mikasa Co., Ltd., 1H-2D, rotation speed: 300 rpm) was used. 20 seconds + 750 rpm - 20 seconds) (Comparative Example 4) Spin coating method (manufactured by Mikasa Co., Ltd., 1H-2D, rotation speed: 300 rpm - 20 seconds + 3000 rpm - 20 seconds) (Comparative Example 5), spray method (Yamanaka) Semiconductor shares limited The company-made display machine (Comparative Example 6) and the dry film (Comparative Example 7) confirmed the formation property of the three-dimensional resin film.

Further, the same material as in Test Example 1 described above was used for the related resin film material.

With respect to the uniform film forming property and the film forming property, the test piece formed by the resin film was observed in a cross section, and the thickness measurement at the A to D point shown in Fig. 4 was performed.

Corresponding laser processing is performed after the resin film is formed, and after performing groove processing using a UV-YAG laser (5370 machine manufactured by ESI Corporation) (laser light wavelength: 355 nm), a digital microscope (KH- manufactured by Hirox Co., Ltd.) is used. 7700) Check if there is any processing failure.

In the related over-plating, after the resin film was formed, a plating core was formed on the entire surface, and the resin film was completely peeled off, and then plating treatment was performed to confirm the presence or absence of plating deposition.

The relevant assessment benchmarks are as follows.

Uniform film formation

Judging from the cross section of the film-forming sample. When the thickness variation of the measurement areas A to D is within 1 μm, it is rated as "◎", if it is 1 to 3 μm, it is evaluated as "△", and if it is 3 μm or more, it is evaluated as "×".

2. Film formability

Judging from the cross section of the film-forming sample. If a film having a thickness of 3 μm or less is formed, it is rated as "◎", and if it is 3 to 5 μm, it is rated as "○", and if it is 5 μm or more, it is rated as "X".

3. Laser processing is poor

The film-forming sample was subjected to groove processing using a UV-YAG laser. After the processing, the case where the resin film adhered to the groove portion was 0 was evaluated as "◎", and the case where 1 or 2 was evaluated was evaluated as "△". "," will be rated as "X" in three or more cases.

4. Overplating

When the plating deposition place is 0, it is rated as "◎", the case of 1 to 2 is rated as "△", and the case where it is more than 3 is rated as "X".

As is apparent from Table 2, when electrostatic spray is used, uniform film formation properties, film formation properties, laser processing defects, and over-plating are good in the case of forming a resin film by other methods. result.

Therefore, it is known that when a resin film is formed into a three-dimensional shape, it is preferable to use an electrostatic spray method.

(Test Example 3: Thickness of resin film)

Next, the relationship between the thickness of the three-dimensional resin film and the circuit formation property was examined.

Using the flat test piece (insulation substrate: developed product of the company) used in Test Example 1 and the test piece having the upper side of 60 μm, the lower side of 180 μm, the height of 100 μm, and the length of 1 mm, which were used in Test Example 2 (insulation substrate: Company's development products).

An electrostatic spray method (ZZ114-1, manufactured by Yamada Advanced Technology Co., Ltd.) was used for the surface of each test piece, and a resin film was formed so that the thickness of the resin film was 1 μm, 3 μm, and 5 μm, and the laser processing defects were evaluated. .

Further, the same material as in Test Example 1 described above was used for the related resin film material.

The evaluation of laser processing failure was performed after the resin film was formed, and after performing groove processing using a UV-YAG laser (5370 machine manufactured by ESI Corporation) (laser light wavelength: 355 nm), a digital microscope (KH- manufactured by Hirox Co., Ltd.) was used. 7700) Check if there is any processing failure.

The evaluation criteria for poor laser processing are as follows.

The film-forming sample was subjected to groove processing using a UV-YAG laser. After the processing, the case where the resin film adhered to the groove portion was 0 was evaluated as "◎", and the case where 1 or 2 was evaluated was evaluated as "△". "," will be rated as "X" in three or more cases.

As is clear from Table 3, if the thickness of the resin film is in the range of 1 to 3 μm, the laser processability is further improved.

As described above, the method of manufacturing a circuit board according to a layout of the present invention includes: a step of forming a photoresist on a surface of the insulating substrate; and forming a laser film on the outer surface of the resin film A circuit forming step of forming a circuit pattern with a recess having a depth greater than a thickness of the resin film; wherein the resin film is formed by electrostatic spraying.

According to this configuration, it is possible to obtain a circuit board which is excellent in uniform film formability, film formability, and laser processability, and which does not have material loss and has high reliability. In particular, when a resin film is formed in a stereoscopic manner, it is judged that an excellent effect can be obtained.

In addition, it is judged that the electrostatic resin spray can be more reliably performed by using a resist resin composition containing at least one solvent having a dielectric constant of 2 or more and a dielectric property of the resin film.

In addition, by using the resin composition for a photoresist having a viscosity of 400 mPas or less, the electrostatic resin spray can be more reliably performed, and it is judged that the above effect can be further enhanced.

Furthermore, the method of manufacturing the circuit board of the present invention is more effective when the circuit board belongs to a three-dimensional surface substrate.

The circuit board of another layout of the present invention is obtained in accordance with the aforementioned manufacturing method.

The present application is based on Japanese Patent Application No. 2011-111534, filed on May 18, 2011, the content of which is incorporated herein.

In order to demonstrate the present invention, the present invention will be appropriately and fully described in the above embodiments with reference to the drawings and the like, but It will be appreciated by those skilled in the art that changes and/or improvements may be made to the embodiments described above. Therefore, the modified form or the modified form implemented by those skilled in the art should be construed as covering the scope of the patent application without departing from the scope of the application claims. In the scope of rights.

Industrial availability

The present invention has a wide range of industrial applicability in the technical field of a circuit board and a method of manufacturing a circuit board.

1‧‧‧Insulating substrate

2‧‧‧ resin film (resistance)

3‧‧‧Circuit slot (recess (circuit pattern)

4‧‧‧through holes (recesses (circuit patterns)

5‧‧‧Electroplating catalyst

6‧‧‧Electrical circuit (electroless plating film)

10‧‧‧ circuit board

11‧‧‧Nozzles

The first (A) to (E) drawings are process diagrams of a method of manufacturing a circuit board according to an embodiment of the present invention.

Fig. 2 is a schematic view showing a state in which a plane is electrostatically sprayed.

Fig. 3 is a schematic view showing a state in which a three-dimensional surface is electrostatically sprayed.

Fig. 4 is a view showing the measurement point of the resin film thickness of the examples.

1‧‧‧Insulating substrate

2‧‧‧ resin film (resistance)

3‧‧‧Circuit slot (recess (circuit pattern)

4‧‧‧through holes (recesses (circuit patterns)

5‧‧‧Electroplating catalyst

6‧‧‧Electrical circuit (electroless plating film)

10‧‧‧ circuit board

Claims (6)

A method of manufacturing a circuit board, comprising the steps of: forming a photoresist film on a surface of an insulating substrate; and forming a circuit, forming a depth greater than a thickness of the resin film based on an outer surface of the resin film The recessed portion forms a circuit pattern; and the resin film is formed by electrostatic spraying. The method for producing a circuit board according to the first aspect of the invention, wherein the resin film is a resist resin composition containing at least one solvent having a dielectric property of a dielectric constant of 2 or more. The method for producing a circuit board according to the first aspect of the invention, wherein the resin film is a resin composition for a photoresist having a viscosity of 400 mPas or less. The method of manufacturing a circuit board according to the first aspect of the invention, wherein the circuit board is a substrate having a three-dimensional surface. The method of manufacturing a circuit board according to the first aspect of the invention, wherein the resin film has a thickness of 1 to 3 μm. A circuit board characterized in that it is manufactured in accordance with the manufacturing method of the first aspect of the patent application.