TWI437939B - Printed circuit board and manufacturing method thereof - Google Patents

Description

Printed circuit board and method of manufacturing same

The invention of the present invention relates to a printed circuit board and a method of manufacturing the same.

Multilayer printed circuit boards are usually fabricated on a printed circuit board (Fig. 3, B, 1), directly laminated (in response to the required copper foil) prepreg (Fig. 3, B, 3), followed by hot pressing. (Fig. 3, B, 4) is executed. By the hot pressing, the prepreg system is completely cured while being pressed against the printed circuit board (Fig. 3, C, 7).

However, the conventional prepreg-covered multilayer printed circuit board thus manufactured is only embossed in the circuit thickness (Fig. 3, C, 5) on the circuit (Fig. 3, C, 2), and lacks flatness. Sex. Further, the prepreg cannot be sufficiently filled in every corner of the root of the circuit, and voids or voids are generated in this portion (Fig. 3, C). As a result, the obtained multilayer printed circuit board has a problem of poor electrical reliability.

Here, in order to solve such a problem, the following manufacturing method is performed. That is, first, the undercoat ink is completely applied to the surface of the printed circuit board (Fig. 4, B, 1) (Fig. 4, B, 8). Next, the coating ink is completely cured (Fig. 4, C, 9). At this time, the portion of the fully hardened layer on the circuit is raised only by the thickness of the circuit (Fig. 4, C, 5), so that the entire hardened layer is completely polished and the printed circuit board is flattened until the circuit is exposed (Fig. 4) D) (Fig. 4 of Patent Document 1, etc.). Thereafter, the prepreg (Fig. 4, 3) is laminated on the surface of the printed circuit board which has been previously flattened, and hot pressing is applied (Fig. 4, 4). By hot pressing, the prepreg system is completely cured while being pressed against the fully hardened layer (Fig. 4, F, 9) (Fig. 4, F, 7). In this way, the flattened prepreg is coated to cover the multilayer printed circuit board (Fig. 4F).

However, in such a manufacturing method, the following problems occur due to surface polishing. In other words, when the surface is polished, the circuit polished to the surface of the circuit is damaged or worn, and the dimensional change of the printed circuit board is increased, and the productivity is lowered.

[Advanced technical literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-108163

In view of the above circumstances, the present invention has an object of producing a flattened prepreg covering a printed circuit board without surface grinding.

In order to achieve the above object, the inventors of the present invention carefully studied the results and completed the following invention.

That is, the first invention of the present invention provides a method of manufacturing a printed circuit board, comprising at least the following engineering composition (I) coating a thermosetting resin ink or a light-and-thermal two-stage hardening type resin ink on a surface of a printed circuit board. a process of semi-hardening the coating ink after at least the convex portion and/or the concave portion; (II) a process of placing the member on the semi-hardened resin in such a manner that the flat surface of the member comes onto the semi-hardened resin; (III) A process in which the member and the printed circuit board are pressure-bonded under heating by a softening temperature of the semi-hardened resin until the semi-hardened resin is completely cured.

According to a second aspect of the invention, there is provided a method of producing a printed circuit board according to the first aspect of the invention, wherein the thermosetting resin ink comprises: an epoxy resin, an acid anhydride, and a thermal hardener; and the optical and thermal two-stage hardening resin ink contains: ethylene-containing Unsaturated double bond bonding compound, photoreaction initiator, epoxy resin and thermal hardener.

According to a third aspect of the invention, there is provided a method of manufacturing a printed circuit board according to the first aspect or the second aspect of the invention, wherein the convex portion is a circuit and the concave portion is an inter-circuit.

According to a fourth aspect of the invention, there is provided a method of manufacturing a printed circuit board according to the third aspect of the invention, wherein the circuit is a copper circuit having a circuit thickness of 35 μm or more.

According to a fifth aspect of the invention, there is provided a method of manufacturing a printed circuit board according to any one of the first invention to the fourth aspect, wherein the member is a prepreg, a copper foil, a copper foil prepreg, and a laminate of the two Any of the above.

According to a sixth aspect of the invention, there is provided a printed circuit board produced by the method of manufacturing a printed circuit board according to any one of the first to fifth aspects of the invention.

According to the present invention, it is possible to produce a flattened prepreg covering the printed circuit board without performing surface grinding. As a result, it is possible to prevent damage or abrasion of the circuit, dimensional change of the printed circuit board, and deterioration in productivity.

Hereinafter, the present invention will be described in detail using the drawings.

In the manufacturing method of the invention of the present invention, first, the engineering (I) is a thermosetting resin ink or a two-stage hardening (first-stage photo-curing + second-stage thermosetting) type resin ink (Fig. 1B, 10). Coating (Fig. 1B) is applied to at least the convex portions (Fig. 1B, 2) and/or the concave portions (Fig. 1 and B, 13) on the surface of the printed circuit board (Fig. 1B, 1). The cloth ink is semi-hardened (Fig. 1 C, 11).

In the item (I), the thermosetting resin ink may include an epoxy resin, an acid anhydride, and a heat curing agent.

In the thermosetting resin ink, specific examples of the epoxy resin include a novolac type epoxy resin compound [phenol phenol resin type epoxy resin, cresol novolac type epoxy resin, etc.], and a bisphenol type epoxy resin. Compound [bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, etc.], triphenylmethane epoxy resin, N-epoxypropyl epoxy resin, alicyclic One or more of epoxy resins.

In the thermosetting resin ink, specific examples of the acid anhydride include a dibasic acid anhydride [maleic anhydride, succinic anhydride, itaconic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, and hexahydroortylene). Formic anhydride, methyl phthalic anhydride, endomethylene tetrahydrophthalic anhydride, methyl endethylene tetrahydrophthalic anhydride, chloro-bromic anhydride, methyl tetrahydrophthalic anhydride, etc., aromatic Group polycarboxylic acid anhydride [trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, etc.], polycarboxylic anhydride derivative [5-(2,5-dioxotetrahydrofuran)-3-methyl-3-cyclohexane One or more of ene-1,2-dicarbonate, etc.

In the thermosetting resin ink, specific examples of the thermosetting agent include amine compounds, imidazole compounds, carboxylic acids, phenols, fourth-order ammonium salts, methylol-containing compounds, and dicyandiamide. And one or more of diaminotriazine compounds.

In the thermosetting resin ink, one or more of a filler, a pigment for coloring, an adhesion imparting agent, an antifoaming agent, a homogenizing agent, a solvent, and an anti-sagging agent are contained as other additives.

In the composition of the thermosetting resin, when the epoxy resin is 100 parts by weight, each of the acid anhydride is preferably 1 to 10 (especially 2 to 5) parts by weight, and the thermosetting agent is preferably 1 to 30 (especially 4 to 10 parts by weight). .

In the work (I), the two-stage hardening type resin ink in the light and heat may be a compound containing an ethylenically unsaturated double bond bond, a photoreaction initiator, an epoxy resin, and a heat hardener.

In the light-and-hot two-stage resin ink, the (meth) propylene-based resin may be mentioned as the ethylenically unsaturated double bond compound. Examples of the (meth)acryl-based resin include polymers composed of (meth)acrylic acid and/or (meth)acrylic acid esters (also referred to as (meth)acrylic acid esters), and A polymer composed of (meth)acrylic acid (ester) and "other monomer".

Among the (meth)acryl-based resins, specific examples of (meth)acrylic acid (meth)acrylic acid, methyl (meth)acrylate or ethyl acrylate, (A) Base) lauryl acrylate, octadecyl (meth) acrylate, dimethoxy (meth) acrylate, iso (meth) acrylate, benzyl (meth) acrylate, ethylene glycol (meth) acrylate Ester or ethylene glycol monoethyl acrylate, ethylene glycol dimethacrylate, ethylene glycol diethoxy methacrylic acid, triglyceride (meth) acrylate, trimethylolpropane (meth) acrylate, ( Methyl)acrylic acid dipentaerythritol hexapropyl ester, (meth) allylate ethoxyethyl ester, hydroxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, ε-(meth) acrylate Lactone denatured tetrahydrofurfuryl acrylate, dimethylamine ethyl (meth)acrylate, decyl (meth)acrylate, (meth) acrylamide, diacetone acrylamide, N-methylol acrylamide, One or more of N-butoxymethyl acrylamide, carbitol (meth) acrylate, 2-carboxyethyl methacrylate or propyl group, and glyceryl (meth) acrylate.

Among the (meth) propylene-based resins, specific examples of the "other monomer" include divinylbenzene, α-methylstyrene, vinyltoluene, p-chlorostyrene, butadiene, and isoprene. One or more of diene, chloroprene, methacryl ketone, vinyl acetate, VeoVa (shell chemical), vinyl propionate, trimethyl vinyl acetate, (meth) acrylonitrile, and the like.

The weight average molecular weight of the (meth)acryl-containing resin is preferably, for example, 500 to 10,000 (especially 1,000 to 3,000).

Examples of the other ethylenically unsaturated double bond-bonding compound include a (meth)acryl-containing monomer. The (meth)acryl-based monomer may specifically be the above-mentioned (meth)acrylic acid or the like.

In the light-and-thermal two-stage curable resin ink, examples of the photoreactive initiator include alcohol ketones, biphenyl dimethyl dimethyl ketones, mercapto phosphine oxides, and amine ketones. Benzoin ethers, benzamidine compounds, benzophenones, thioxanthones, biimidazoles, dimethylaminobenzoate, triarylsulfonates, terpenes, acridones, anthraquinones One or more of a pyridine, a carbazole, a titanium complex, and the like.

In the case of the heat-curable resin ink, the epoxy resin and the heat-curing agent are specifically exemplified in the above-mentioned thermosetting resin ink.

Examples of the other additives include a sensitizer, a superposition inhibiting agent, and the above-mentioned thermosetting resin ink.

In the composition of the light-and-hot two-stage hardening type resin ink, when the weight ratio of the ethylenically unsaturated double bond-bonding compound 100 is 100, the photoreactive initiator is 0.1 to 10 (especially 1 to 5) parts by weight. The epoxy resin is preferably used in an amount of 10 to 100 (especially 20 to 50) parts by weight and 1 to 20 parts by weight (particularly 2 to 10 parts by weight).

In the case of the project (I), the convex portion may specifically include a circuit, a wafer component, a surface-mounted bare crystal, or the like. The effect of the present invention (especially, the flatness of the printed circuit board) is such that the thickness of the convex portion (the height from the surface of the substrate) is larger and more prominent. Examples of such a convex portion include a circuit (a copper circuit or the like) having a thick wall (specifically, a circuit thickness of 35 μm or more, typically 50 to 600 μm).

In the case of the project (I), the recessed portion may be a gap between the convex portion and the convex portion (such as between circuits) or a hole (a via hole, a through hole, or the like).

In the engineering (I), at least the convex portion (all or part of) and/or the concave portion (all or part of) are coated. Specifically, the coating is applied to all of the convex portions and all the concave portions (including the entire coating of the printed circuit board) (first drawing), one of the convex portions and the concave portion (second FIG. A), and the convex portion. All of (only) (Fig. 2B) or recesses (only) (Fig. 2C) are performed. When the coating amount is applied to all of the convex portions and the entire concave portion, for example, when the convex portion is a circuit, the circuit is 5 to 50 (especially 10 to 30) μm, and the circuit is 0.7 to 1.0 of the circuit thickness (especially The thickness is preferably 0.8 to 0.9 times. When the coating amount is too large, the amount of exposure from the peripheral portion at the time of the pressure-bonding member increases, and when it is too small, sufficient flatness cannot be obtained. Coating can be performed by, for example, screen printing, metal mask printing, roll coating printing, bar coating printing, and the like.

In the work (I), the coating ink is semi-hardened. "Semi-hardening" also includes incomplete hardening of a single-stage hardening type resin, and hardening of a multi-stage hardening type resin in the middle. The semi-hardening of the thermosetting resin ink is carried out by, for example, heating at 80 to 130 (especially 100 to 120) ° C for 10 to 60 (especially 20 to 30) minutes. The semi-hardening (first-stage photocuring) of the above-mentioned light- and heat-stage hardening type resin ink is performed by a wavelength of 300 to 500 (especially 350 to 450) nm, and an irradiation amount of 0.1 to 5 (especially 0.5 to 2) J/cm ² The light is irradiated.

Next, in the item (II), the members (Figs. D and 3) are placed on the semi-cured resin (Figs. D and 11) so that the flat surface of the member comes to the semi-hardened resin surface.

In the engineering (II), the member is at least one side flat, such as a film, a sheet or a flat plate. Specific examples of the member include a prepreg, a copper foil, a copper foil prepreg, and a laminate of two or more of them.

In the work (II), the member is placed on the semi-hardened resin. At this time, the member is placed on the semi-hardened resin in such a manner that the flat surface of the member comes to the semi-hardened resin surface, that is, the flat surface of the member and the surface of the semi-hardened resin face each other.

Next, in the item (III), the member (Fig. 1 and D) is pressed against the printed circuit board (Fig. 1, D, 1) under heating of the softening temperature of the semi-hardened resin (Fig. 1D). 4) The semi-hardened resin (Fig. 1 and D, 11) is completely cured (Fig. 1 and E).

In the work (III), the following steps are specifically carried out. That is, first, the semi-hardened resin is softened by heating. Accordingly, the semi-hardened resin is forced to be uniform in surface by the pressure of the flat surface of the member, and becomes flat. Then, in this state, the semi-hardened resin is crimped to the member and completely cured. As a result, a member (prepreg or the like) is laminated on the flattened fully cured resin, so that a printed circuit board having a high degree of flatness is produced.

In the work (III), the heating is performed at a temperature higher than the softening temperature of the semi-hardened resin. The softening temperature of the semi-hardened resin is preferably from 80 to 160 (especially from 120 to 150) °C. When the softening temperature is too low, the semi-hardened resin is exposed from the end surface, and the printed circuit board or the press is contaminated. When the softening temperature is too high, the flattening is insufficient. The viscosity at the time of softening of the semi-hardened resin is 10000 mPa applied at a frequency of 1 Hz when measured by an ammeter (that is, heated while applying a fine vibration of a sine wave, and the viscosity is calculated from the resistance at this time). When the stress is ‧ s, it is better to use 1~1000 (especially 10~100) Pa‧s. When the viscosity value is too small, the fluidity is too high. However, when it is exposed from the substrate, when it is too large, there is a case where the fluidity is insufficient and sufficient flattening cannot be obtained.

In the work (III), the heating is preferably carried out at a temperature higher than the complete hardening temperature of the semi-hardened resin. In terms of the complete softening temperature of the semi-hardened resin, it is preferably 150 to 200 (especially 160 to 180) °C.

In the work (III), the crimping is performed until the semi-hardened resin is completely cured by the above heating. When the member is a prepreg of the B table, it is preferable to press the prepreg until it is completely cured (Fig. 1 and Fig. 1). The crimping can be carried out in particular by vacuum stamping or the like. In terms of crimping conditions, the pressure is 0.1 to 5 (especially 2 to 3) MPa by heating, for example, at 100 to 250 (especially 130 to 190) ° C, 10 to 200 (especially 90 to 120) minutes. .

As described above, when the thermosetting resin ink or the optical or thermal two-stage curable resin ink is applied to all of the convex portions on the surface of the printed circuit board and all the concave portions, the flat surface shown in FIG. The prepreg covers the printed circuit board.

Similarly, when applied to one of the convex portions and the concave portion, when applied to all of the convex portions (only) in FIG. 2A, the second FIG. B' and the concave portion (only In all cases, a flattened prepreg printed circuit board as shown in Fig. 2C' is produced.

According to the manufacturing method of the present invention, a prepreg having a surface unevenness of 5 μm or less can be produced to cover a printed circuit board.

[Examples]

Hereinafter, the invention will be specifically described by way of examples.

[Pre-impregnation covering printed circuit board manufacturing]

‧Example 1

Thermosetting resin ink composition (parts by weight): bisphenol A type epoxy resin (100), tetrahydrophthalic anhydride (20), barium sulfate powder (120), "Ajicure PN-23" (Japan Ajinomoto Fine) Manufactured by Techno, a heat hardener) (6), eucalyptus oil (1).

The above-mentioned thermosetting resin ink was entirely applied by screen printing to a printed circuit board on which a copper circuit (circuit thickness: 70 μm, L/S 100 μm) was formed. The coating thickness was 25 μm on the circuit and 60 μm between the circuits. After coating, the printed circuit board was placed in a dryer and heated at 110 ° C for 60 minutes to semi-harden the coating ink.

Next, a prepreg ("R-1551") manufactured by Panasonic Electric Co., Ltd., having a thickness of 0.1 mm) was placed on the semi-cured resin layer.

Next, the prepreg and the printed circuit board are pressure-bonded and integrated by vacuum pressing. The stamping conditions were 180 ° C, and the pressure was 3 MPa under heating for 120 minutes.

The prepreg-covered printed circuit board thus manufactured was subjected to a surface roughness meter ("Surfcom 130R" manufactured by Tokyo Precision Manufacturing Co., Ltd.), and the surface unevenness was 5 μm or less. When the cross section was observed with a stereoscopic microscope (50 times), the root portion of the circuit was observed. No gaps at all.

‧Example 2

Light and heat two-stage hardening resin ink composition (parts by weight): phenolic phenolic resin type epoxy resin and acrylic acid reactant (100), trimethylolpropane triacrylate (100), "IIRGACURE-907" (Cibageigy Manufactured, bisphenol A type epoxy resin (60), Ajicure PN-23" (manufactured by Ajinomoto Fine Techno Co., Ltd.) (6), eucalyptus oil (1), cerium oxide powder (200).

The above-mentioned optical and thermal two-stage curable resin ink is applied in the same manner as described above, and is printed on the printed circuit board on which the copper circuit is formed. After the application, the printed circuit board was irradiated with light at a wavelength of 365 nm and an irradiation amount of 0.6 J/cm ² to semi-harden the coating ink.

Next, in the same manner as described above, the prepreg was covered with the semi-hardened resin layer, and the prepreg and the printed circuit board were pressure-bonded by vacuum pressing under heating.

With respect to the prepreg-covered printed circuit board thus produced, the surface unevenness was 5 μm as a result of investigation of the surface roughness meter, and when the cross section was observed by the stereoscopic microscope, there was no void at all.

‧Comparative example 1

Two resin films ("ABF-GX3"), manufactured by Ajinomoto Fine techno Co., Ltd., having a film thickness of 50 μm and a softening temperature of 130 ° C, were placed over the printed circuit board on which the copper circuit was formed.

Next, the resin prepreg and the printed circuit board were integrally formed by vacuum press bonding. The stamping conditions were 180 ° C, and the pressure was 3 MPa under heating for 120 minutes.

With respect to the resin-covered printed circuit board thus produced, there was no void as a result of the above-described physical microscope investigation. However, at the time of press, the resin film is softened and softened by hot pressing, and flows out from the side surface of the printed circuit board. As a result, not only the thickness of the resin film on the circuit is unstable, but also the printed circuit board or the press machine is contaminated.

‧Comparative example 2

A resin-coated printed circuit board was produced except that the stamping temperature was changed from 180 ° C to 150 ° C except that it was the same as in Comparative Example 1.

At the time of pressing, the resin film did not become liquid. However, with respect to the manufactured resin-covered printed circuit board, the surface unevenness was 20 μm or more as a result of the above-described surface roughness investigation. As a result of the above-described physical microscope investigation, the prepreg could not be sufficiently filled to the corners of the connecting portion of the circuit. , a gap is created in this portion.

‧Comparative example 3

A prepreg-covered printed circuit board was produced in the same manner as in Comparative Example 1, except that a prepreg ("R-1551", thickness: 0.1 mm) was used instead of the resin film ("ABF-GX3").

With respect to the printed circuit board covered with the prepreg thus produced, the difference in surface unevenness was 40 μm or more as a result of the above-described surface roughness measurement.

1. . . Printed circuit board

2. . . Convex (circuit)

3. . . Component (B table prepreg)

4. . . Crimp (hot press)

5. . . Uplift

6. . . Void

7. . . Component (completely hardened prepreg)

8, 10. . . Unhardened coating resin

9,12. . . Completely hardened coating resin

11. . . Semi-hardened coating resin

13. . . Concave (inter-circuit)

Fig. 1 is a cross-sectional view showing the construction of a printed circuit board according to the present invention.

Fig. 2 is a cross-sectional view showing another aspect of a method of manufacturing a printed circuit board relating to the present invention.

A to C each indicate a state in which a resin ink is applied onto the surface of a printed circuit board. Each of A' to C' represents a printed circuit board which is flattened.

Fig. 3 is a cross-sectional view showing the construction of a conventional printed circuit board.

Fig. 4 is a cross-sectional view showing another aspect of the conventional method for manufacturing a printed circuit board.

1. . . Printed circuit board

2. . . Convex (circuit)

3. . . Component (B table prepreg)

4. . . Crimp (hot press)

7. . . Component (completely hardened prepreg)

10. . . Unhardened coating resin

12. . . Completely hardened coating resin

11. . . Semi-hardened coating resin

13. . . Concave (inter-circuit)

Claims (6)

A method of manufacturing a printed circuit board, characterized in that at least a convex portion of a surface of a printed circuit board is coated with a thermosetting resin ink or a photo-curable two-stage hardening type resin ink at least from the following engineering configuration (I) And/or after the recess, the semi-hardening of the coating ink; (II) the process of placing the member on the semi-hardened resin in such a manner that the flat surface of the member comes to the semi-hardened resin surface; and (III) The member and the printed circuit board are pressed under the heating of the softening temperature of the semi-hardened resin until the semi-hardened resin is completely hardened. In the above-mentioned item (III), the viscosity at the softening of the semi-hardened resin is applied at a frequency of 1 Hz. When the stress is 10000 mPa‧s, it is 1~1000 Pa‧s. The method for producing a printed circuit board according to the first aspect of the invention, wherein the thermosetting resin ink comprises: an epoxy resin, an acid anhydride, and a thermal curing agent, and the optical and thermal two-stage hardening resin ink contains: ethylene-containing Saturated double bond bonding compound, photoreaction initiator, epoxy resin and thermal hardener. The method of manufacturing a printed circuit board according to the first or second aspect of the invention, wherein the convex portion is a circuit and the concave portion is an inter-circuit. The method of manufacturing a printed circuit board according to the third aspect of the invention, wherein the circuit is a copper circuit having a circuit thickness of 35 μm or more. The method of manufacturing a printed circuit board according to the first aspect of the invention, wherein the member is a prepreg, a copper foil, a copper foil prepreg, and a laminate of the two or more. A printed circuit board manufactured by the method of manufacturing a printed circuit board according to any one of claims 1 to 5.