WO2005104638A1

WO2005104638A1 - Wiring board and method for producing the same

Info

Publication number: WO2005104638A1
Application number: PCT/JP2005/007548
Authority: WO
Inventors: Yasuo Fukuhara; Kenji Ogasawara; Tomoaki Watanabe; Keiko Kashihara
Original assignee: Matsushita Electric Works, Ltd.
Priority date: 2004-04-23
Filing date: 2005-04-20
Publication date: 2005-11-03
Also published as: JPWO2005104638A1; TWI290816B; TW200603705A

Abstract

A wiring board exhibiting high adhesion between a substrate and a conductive layer, and its production method. A transfer sheet (8) having a protruding/recessed surface of specified surface roughness is formed integrally with the substrate such that the protruding/recessed surface is transferred to the surface of the substrate (1), and then the transfer sheet is removed from the substrate, thus performing first surface roughening. The substrate surface roughened by the first surface roughing is then chemically roughened using etching liquid, thus performing second surface roughening. Subsequently, a conductive layer (7) is formed on the substrate surface subjected to first and second surface roughening preferably by an additive method.

Description

Specification

Wiring board and method of manufacturing the same

Technical field

The present invention relates to a wiring substrate and a method for manufacturing the same, and more particularly to a substrate surface roughening treatment performed before forming a conductive layer.

Background art

[0002] With the recent trend toward smaller and lighter electronic Z-electric devices, there is a tendency for printed wiring boards incorporated therein to be thinner, and various improvements have been made in manufacturing methods thereof.

[0003] For example, Japanese Patent Application Laid-Open No. 5-136575 proposes a method of manufacturing a multilayer printed board that can reduce the thickness of a multilayer printed board and reduce warpage and twist during component mounting. In this method, as shown in FIGS. 8A and 8B, a resin film 25 with a protective film 26 is arranged on the surface of an inner layer base material 5 having a predetermined inner layer circuit 4 to form a laminate. After the formation, the laminate is integrally formed using a vacuum laminator. In this case, the resin film 25 functions as an insulating layer. Next, as shown in FIG. 8C, the protective film 26 is peeled off, and an outer layer circuit 70 is formed on the exposed resin film 25 by using an additive method. Thus, a multilayer printed board as shown in FIG. 8D is obtained. In the drawing, reference numerals 71 and 72 denote through-hole plating and blind via holes for electrically connecting the inner layer circuit 4 and the outer layer circuit 70.

[0004] In the multilayer printed board manufactured in this manner, the use of the resin film 25 allows the insulating layer to be formed thin, and the fine pattern can be formed by employing the additive method. . However, there is still room for improvement in the adhesion of the outer layer circuit 70, and there is also a problem that the use of the resin film 25 lowers the rigidity of the multilayer printed board.

Disclosure of the invention

[0005] Therefore, a main object of the present invention is to achieve a high adhesion strength of the conductive layer and to flexibly cope with demands for improved insulation reliability and improved rigidity. An object of the present invention is to provide a method for manufacturing a line substrate.

[0006] That is, the production method of the present invention comprises a first roughening treatment for physically roughening the surface of a substrate containing an electrically insulating resin composition as a main component, and a first roughening treatment. A second roughening process for chemically roughening the roughened substrate surface by using an etchant; and forming a conductive layer on the substrate surface roughened by the second roughening process. And a process.

[0007] A further object of the present invention is to provide a wiring board obtained by the above-described manufacturing method. In this wiring board, the material constituting the conductive layer is formed by a first roughening treatment and a second roughening treatment. It is characterized by having an interface structure between a substrate and a conductive layer formed so as to penetrate the unevenness of the surface roughened by the roughening treatment.

[0008] According to the present invention, the contact area between the conductive layer and the substrate can be remarkably increased, and the conductive layer is firmly attached to the substrate by the effect of anchoring the conductive layer material to the irregularities on the substrate surface. Therefore, high adhesion of the conductive layer can be achieved.

[0009] In the above invention, the first roughening treatment includes a step of integrally forming a sheet having an uneven surface with a predetermined surface roughness with the substrate such that the uneven surface is transferred to the substrate surface; Removing the sheet from the substrate to obtain a physically roughened substrate surface. In particular, a process in which a sheet is made of a metal such as copper and the sheet is removed by etching to obtain a physically roughened substrate surface, or a sheet coated with a release agent containing an inorganic filler on the surface. It is preferable to employ any one of the steps of using the sheet and peeling off the sheet to obtain a physically roughened substrate surface.

[0010] When the first surface roughening treatment described above is employed, the uniformity of the treatment effect is higher than when the surface roughening treatment is performed by a method such as grinding or sandblasting, and therefore, a higher! Therefore, the adhesion can be reproduced with high reliability.

[0011] In the above invention, the substrate includes particles made of a material dispersed in the electrically insulating resin composition and preferentially dissolved by the etching solution. It is preferable that the etching is performed by preferentially dissolving the particles distributed near the surface of the substrate roughened by the surface roughening treatment with an etching solution.

In this case, by changing the amount, shape, and size of the dispersed particles, the second coarse The amount, shape, and size of the irregularities introduced into the substrate surface by the surface roughening process can be controlled, especially when the thin surface printed wiring board is manufactured in combination with the first surface roughening process described above. Even in this case, the optimum surface roughening treatment can be efficiently performed from both viewpoints of improving the adhesion of the conductive layer and securing the electrical insulation.

In the first and second roughening treatments, the surface roughness of the substrate is 3 to 15 μm in Rz (10-point average roughness) and 0.1 to 1.0 μm in Ra (arithmetic average roughness). It is preferred to be implemented to be m! / ,. When the thickness of a substrate such as a pre-preparer made by impregnating a fibrous base material with an electrically insulating resin composition is small, if the Rz exceeds 15 / zm or the Ra exceeds 1.0 m, the wiring substrate There is a possibility that insulation reliability in the depth direction of the semiconductor device may decrease. When Rz is less than or Ra is less than 0.1 / zm, the effect of improving the adhesion strength of the conductive layer tends to decrease.

[0014] The conductive layer is preferably formed by an additive method. The interface structure described above can be formed with high reliability, and a fine pattern can be easily formed.

[0015] Further objects and effects of the present invention will be more clearly understood from the following best mode for carrying out the invention.

Brief Description of Drawings

[FIG. 1] (a) to (e) are schematic process diagrams of a two-step surface roughening treatment which is performed by a preferred embodiment of the present invention.

FIG. 2 is an SEM photograph of a substrate surface before a first surface roughening treatment.

FIG. 3 is an SEM photograph of the substrate surface after the first roughening treatment.

FIG. 4 is an SEM photograph of the substrate surface after the second roughening treatment.

FIG. 5 is a schematic cross-sectional view showing one example of a transfer sheet used for a first roughening treatment.

FIGS. 6 (a) to 6 (d) are schematic process diagrams showing a method for manufacturing a printed wiring board, which is preferred according to an embodiment of the present invention.

[FIG. 7] (a) to (g) are schematic process diagrams showing another method for producing a printed wiring board, which is useful for preferred embodiments of the present invention.

8 (a) to 8 (d) are schematic process diagrams showing a conventional method for manufacturing a printed wiring board. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a wiring board of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

The substrate used in the present invention contains an electrically insulating resin composition as a main component. The resin composition is not particularly limited, but for example, an epoxy resin such as a phosphorus-containing epoxy resin, a brominated epoxy resin, or a cresol novolak type epoxy resin can be used. In addition, the resin composition may contain a curing agent such as dicyandiamide, a curing accelerator such as 2-ethyl-4-methylimidazole, and, if necessary, a filler such as silica or dimethylformamide (DMF). Organic solvents may be blended.

When a prepreg produced by impregnating a fibrous base material with the electrically insulating resin composition is used as a substrate, the fibrous base material can increase the rigidity of the printed wiring board. . It is preferable to use a fibrous base material having a thickness of 0.1 mm or less in order to reduce the size and thickness of the printed wiring board while maintaining appropriate rigidity. Specifically, "WEA1116" (a glass cloth having a thickness of 0.08 mm) and "WEA1078" (a glass cloth having a thickness of 0.04 mm) manufactured by Nittobo can be used. The thickness of the fibrous base material is a force appropriately set according to the thickness dimension of the substrate. The lower limit of the thickness can be set to, for example, 0.019 mm (19 ^ m). After impregnating the fibrous base material with the resin composition, the obtained impregnated body is heated and dried by a drier to obtain a semi-cured B-stage prepreg.

[0020] Further, in order to effectively perform the second surface roughening treatment described below, particles made of a material preferentially dissolved by the etching solution used in the second surface roughening treatment are contained in the resin composition. It is preferable to disperse them in FIG. 1A illustrates a flat surface state of the substrate 1 before the first roughening treatment, and the above-described particles 20 are uniformly dispersed in the substrate 1. Further, the SEM photograph of FIG. 2 shows that the substrate surface before the first surface roughening treatment is flat.

Next, a first roughening process for physically roughening the surface of the substrate 1 is performed. In the first roughening treatment, a transfer sheet 8 having an uneven surface with a predetermined surface roughness is integrally formed with the substrate such that the uneven surface is transferred to the surface of the substrate 1 from the viewpoint of processing efficiency and uniformity of the processing effect. (FIG. 1 (b)) and a step of removing the transfer sheet 8 from the substrate 1 to obtain a physically roughened surface of the substrate (FIG. 1 (c)). . Specifically, transfer to substrate 1 There are a method of etching and dissolving and removing the transfer sheet after integrally forming the sheet 8, and a method of peeling and removing the transfer sheet.

When the substrate is roughened by dissolving and removing the transfer sheet 8, a release metal foil such as an electrolytic copper foil can be used as the transfer sheet 8, for example. In this case, the surface to be engaged against the substrate 1 of the electrolytic copper foil, and 4 to 12 _i um of Rz (10-point mean roughness), good to have a Ra (arithmetic average roughness) of 0.3~0.7m The surface roughness of this transfer sheet is transferred to the substrate 1. The existing copper etching solution is used to dissolve the transfer sheet.

When the transfer sheet 8 is peeled to roughen the substrate 1, for example, a transfer sheet can be prepared by applying a release agent containing an inorganic filler to the sheet material. The release agent facilitates peeling of the transfer sheet after lamination molding. Specifically, as shown in FIG. 5, first, a film-like polyethylene terephthalate (PET) 13 is adhered to an aluminum foil 15 with an adhesive 14 to produce a sheet material 12, and then a sheet of polypropylene (PP) or the like is formed. The transfer sheet 8 can be prepared by mixing 5 to 15% by mass of the inorganic filler 10 such as crushed silica with the release agent 11 and applying the mixture to the surface of the aluminum foil 15 of the sheet material 12. . The average particle size of the inorganic filler 10 is not particularly limited, but is preferably 1 to LO / zm. The surface coated with a release agent 11 containing the inorganic filler 10 is to be closed with 4 to 12 _i um of Rz (10-point mean roughness), 0.3～0.7M of Ra (arithmetic mean roughness) The unevenness on this surface is transferred to the substrate surface.

FIG. 1 (b) illustrates a state in which the transfer sheet 8 is integrally formed on the surface of the substrate 1, and FIG. 1 (c) illustrates a state in which the transfer sheet 8 is peeled off. The appearance of the irregularities being transferred to the substrate surface is depicted. FIG. 3 is a SEM photograph of the substrate surface after the transfer sheet was peeled off, and it can be seen that irregularities of several microns were uniformly formed on the substrate surface. According to the first surface roughening treatment using the transfer sheet 8 described above, it is possible to achieve an excellent adhesiveness improvement effect and its reliability, which are superior to the case where the surface is roughened by grinding or sandblasting. In other words, when the substrate surface is roughened by grinding, the substrate material near the surface is crushed, so even if a conductive layer is formed thereon, the conductive layer is peeled off together with the crushed substrate material. As a result, there is a possibility that the expected improvement in adhesion cannot be obtained. Also, when mechanically roughening the substrate surface by sandblasting, etc. In some cases, the sprayed particles may remain on the substrate surface and adversely affect the adhesion of a conductive layer formed thereafter. In addition, surface roughening by grinding or sandblasting tends to cause variations in processing effects.

[0025] On the other hand, according to the first roughening treatment using the transfer sheet, the size and shape of the unevenness to be formed on the substrate can be controlled immediately and when the processing area of the substrate is large. However, there is an advantage that a uniform processing effect can be achieved over the entire substrate. For this reason, it is particularly preferable to carry out the first roughening treatment of the present invention by removing the transfer sheet 8 from the substrate 1.

Next, a second surface roughening process for chemically roughening the substrate surface roughened by the first surface roughening process by using an etchant is performed. In the second surface roughening treatment, a substrate in which the particles 20 are dispersed is used, and the particles 20 distributed near the surface of the substrate roughened by the first surface roughening treatment are etched. U, particularly preferred to do by preferential dissolution.

As the particles 20 that are preferentially dissolved in the etching solution, for example, a crosslinked elastomer such as a butadiene-acrylo-tolyl copolymer, a polyvinyl acetal, or the like can be used. The blending amount of the particles can be appropriately set. For example, the blending amount of the particle components is preferably 1 to 20% by mass based on the total amount of the resin composition. In addition, the average particle size of the particles 20 dissolved by the second surface roughening treatment is 0.1 to 2/2 from the viewpoint of effectively forming fine irregularities on the surface subjected to the first surface roughening treatment. It is preferable to be in the range of zm.

[0028] As an etching solution for dissolving the particles 20, a solution containing at least one of an acid and an oxidizing agent can be used. For example, "Circuposit MLB211" manufactured by Shipley Co., Ltd., "Enplate MLB497" manufactured by Meltex Co., Ltd., and Meltex Co., Ltd. A set of three types of “Enplate MLB-791M” manufactured by the company can be used as an etching solution. Here, "Circuit MLB211J has an ethylene glycol aqueous solution as a main component and has a function to swell the resin." Enplate MLB497 "has a potassium permanganate aqueous solution (oxidizing agent) and a potassium hydroxide aqueous solution as main components. And has the function of dissolving fats, especially soluble components. Under the basic condition, permanganate such as potassium permanganate acts strongly as an oxidizing agent. As a solution having the function of dissolving fat, sodium permanganate aqueous solution (acid And an aqueous solution of sodium hydroxide and sodium hydroxide. "The ENPLATE MLB-791MJ is composed mainly of an aqueous solution of sulfuric acid (acid) and an aqueous solution of hydrogen peroxide, and has a function to neutralize a basic condition.

When the second surface roughening process is performed, the particles 20 near the uneven surface of the substrate 1 transferred by the first surface roughening process are preferentially dissolved by the etching solution, and FIG. 1 (d) As shown in FIG. 7, finer irregularities are formed on the irregular surface of the substrate. FIG. 4 is an SEM photograph of the substrate surface after performing the second surface roughening treatment on the surface subjected to the first surface roughening treatment in FIG. 3, and as apparent from the comparison between FIG. 3 and FIG. Many fine irregularities are formed by the second surface roughening treatment on each of the irregularities formed by the first surface roughening treatment. As described above, by performing the second surface roughening treatment subsequent to the first surface roughening treatment, the surface area of the substrate can be significantly increased. Note that if implemented only the second roughening a substrate having a flat surface, the base plate surface, l~5 _i um and Rz (10-point mean roughness) of, 0.03～0.4M of Ra ( A force that only forms relatively fine irregularities (arithmetic average roughness) As noted above, preferably, Rz (10-point average roughness) of 4-12 / ζπι and R of 0.3-0.7 m _{a When} combined with the first roughening process for forming (rough! /,) concave and convex with relatively large (arithmetic mean roughness), the surface roughness after the second 1¾ (10 points average roughness) 3-15! ^ And Ra (arithmetic mean roughness) can be 0.1 to 1.Ο μm.

Next, a conductive layer 7 is formed on the surface of the substrate 1 roughened by the second roughening treatment. As shown in FIG. 1 (e), the conductive layer 7 causes the material constituting the conductive layer to bite into the unevenness of the surface roughened by the first roughening treatment and the second roughening treatment (anchor). Effect). According to the interface structure between the conductive layer 7 and the substrate 1 obtained in this way, the contact area between the conductive layer and the substrate can be significantly increased, and the substrate surface of the conductive layer material can be increased. The conductive layer is firmly held on the substrate by the anchor effect on the irregularities. The method for forming the conductive layer is not particularly limited as long as it is a method suitable for forming the above-described interface structure. However, as described later, it is particularly preferable to employ an additive method. In addition, the additive method includes a full additive method and a semi-additive method. In the present invention, a deviation method may be used!

[0031] As described above, according to the present invention, the combination of the physical surface roughening treatment and the chemical surface roughening treatment is performed. In particular, the first surface roughening treatment for transferring the irregularities of the transfer sheet to the substrate to physically roughen the substrate surface, and the etching and removal of the particles dispersed inside the substrate by preferential etching. A high adhesion between the conductive layer and the substrate can be reliably achieved by a combination with the second surface roughening treatment for roughening the surface.

Next, an example of the method for manufacturing a multilayer printed wiring board of the present invention will be specifically described.

As shown in FIG. 6 (a), the fibrous base material 3 is impregnated with the electrically insulating resin composition 2 on the inner substrate 5 on which the predetermined inner circuit 4 is formed on both sides. After placing the prepreg 30 produced in this manner and further arranging the transfer sheet 8 on the prepreg 30, as shown in FIG. 6 (b), these are integrally laminated by a molding method such as a multi-stage vacuum press. Mold. The inner layer substrate 5 can be manufactured, for example, by laminating and forming a required number of pre-predaders 30, and the inner layer circuit 4 can be formed by an additive method or a subtractive method. Further, the circuit may be formed on a laminate such as a commercially available copper-clad laminate. Alternatively, the pre-predator 30 may be disposed only on one side of the inner layer substrate 5 and laminated and formed. Further, prior to lamination molding, the inner layer circuit 4 of the inner substrate 5 may be subjected to a surface roughening treatment such as a black oxide treatment.

Next, as shown in FIG. 6 (c), the transfer sheet 8 is removed, so that the insulating layer 6 is formed by the pre-reader 30, and at the same time, the unevenness of the transfer sheet is transferred to the surface of the pre-reader. As described above, since the surface of the insulating layer can be roughened simultaneously with the formation of the insulating layer, manufacturing efficiency can be improved. The surface roughening treatment by the transfer sheet 8 is intended to increase the surface area of the pre-preda 30 by the unevenness formed on the pre-preda 30 (insulating layer 6). The length is determined according to the thickness of the pre-preda. For example, when a thin pre-preda is used to reduce the thickness of a wiring board, if the depth of the irregularities formed by the surface roughening treatment is excessively deep, insulation reliability in the thickness direction may be reduced. For example, when the surface is roughened by sand blasting or the like, if the processing time becomes longer, the thickness of the pre-preda becomes thinner, which may cause a problem in insulation reliability. By simply using a transfer sheet with an uneven surface roughness, it is possible to provide a pre-preda with the same surface roughness with good reproducibility, facilitate quality control, and reduce defects that occur during the pretreatment process. Reduce and increase yield You can do it.

Next, a second surface roughening treatment is performed using an etching solution. The second surface roughening treatment can be performed by immersing the laminate shown in FIG. 6 (c) in an etching solution, and can be performed a plurality of times by changing the type of the etching solution. For example, the temperature of the etching solution can be set at 40 to 90 ° C, and the immersion time can be set at 1 to 30 minutes. When using the three types of circuposit MLB211, eneplate MLB497 and eneplate MLB-791MJ as an etching solution as a set, first immerse the laminate in circuposit MLB211. The resin is swelled, and then the laminate is immersed in “Enplate MLB497” to dissolve the resin. Finally, the laminate is immersed in “Enplate MLB-79 1M” to neutralize the basic condition. By performing the sum, the second roughening treatment can be performed. Ideally, after the first surface roughening treatment using the transfer sheet is performed, the second surface roughening treatment using etching is ideally performed. Does not exclude performing the second surface roughening process after performing.

Thereafter, the outer layer circuit 70 is formed on the surface of the first and second roughened insulating layer 6 by the additive method, and the outer layer circuit on the inner layer circuit 4 and the insulating layer 6 as necessary. By forming through-hole plating 71 for connecting 70, a multilayer printed wiring board as shown in FIG. 6D is obtained. The printed wiring board shown in FIG. 6 (d) is a four-layer board. The present invention is not limited to this. The above-mentioned four-layer board is used as the inner-layer board 5, and further multilayered through the same process. A printed wiring board can be manufactured.

Next, an example of a method for manufacturing a printed wiring board when a semi-additive method is used as a method for forming the outer layer circuit 70 will be described.

First, as shown in FIG. 7 (b), a through-hole 50 for forming a through-hole plating and a blind-by hole are formed on the laminated body shown in FIG. A hole 52 reaching the inner layer circuit 4 for forming a hole is formed by a drill or the like. Note that the laminated body shown in FIG. 7A can be manufactured in the same manner as in FIG. 6C, and a duplicate description will be omitted.

Next, as shown in FIG. 7 (c), a plating layer 40 is formed on the surface of the insulating layer 6 composed of the pre-predader 30 by performing electroless plating. Next, as shown in Fig. 7 (d), the outer layer A plating resist 60 is formed in a portion where the formation of the path 70 is not required. Further, as shown in FIG. 7 (e), an electrolytic plating process such as electrolytic copper plating is performed to form an electrolytic plating layer 43 on a portion where the plating resist 60 is formed.

Next, as shown in FIG. 7 (f), after exposing the electroless plating 40 by removing the plating resist 60, this is removed by quick etching (flash etching). A multilayer printed wiring board on which the outer layer circuit 70 is formed as shown in g) can be obtained. By forming the electroless plating 40 and the electrolytic plating 43 on the inner surface of the through-hole 50 52 hole 52, the through-hole plating 71 for electrically connecting the inner layer circuit 4 and the outer layer circuit 70 and the blind via are provided. Hole 72 is formed. Incidentally, after-curing is appropriately performed.

Example

Hereinafter, the present invention will be specifically described based on examples.

In this example, three types of pastes, 1, 1, ..., 3, were prepared by mixing the components in the amounts shown in Table 1.

The phosphorus-containing epoxy resin used for preparing the varnish “Γ” was obtained as follows. First, a 300 ml three-necked flask was equipped with a stirrer and a condenser, and then the flask was dimethylated. After a predetermined amount of formamide (DMF) and methoxypropanol (MP) were added, epoxy resin (53 parts by mass of “Epiclone 850S” and 13 parts by mass of “Epiclone N690” manufactured by Dainippon Ink and Chemicals, Inc.) was added. The epoxy equivalents of "Epiclone 850S" and "Epiclone N690" are 190 and 220, respectively.

[0042] Thereafter, when the obtained mixture was heated in an oil bath to reach 80 ° C, 16 parts by mass of a phosphorus compound (manufactured by Sanko Chemical Co., Ltd.) represented by the following [Chemical Formula 1] was charged, and further heated. did. When the temperature reached 100 ° C., triphenylphosphine was added at a rate of 0.2% by mass based on the total solid content, and the phosphorous conjugate was reacted with the epoxy resin. Then, when a predetermined epoxy equivalent was reached, the reaction was terminated to obtain a phosphorus-containing epoxy resin solution. Incidentally, ₀ which Make by measuring the epoxy equivalent weight based on the progress ί Contact IS K 7236- 1995 of the reaction [0043] [Formula 1]

[0044] The brominated epoxy resin used for the preparation of varnishes "2" and "3" was "Y DB-500" manufactured by Toto Kasei Co., Ltd., and the cresol novolak type epoxy resin was obtained from Dainippon Ink & Chemicals, Inc. "Epiclon 690" Dicyandiamide (molecular weight 84, theoretically active hydrogen equivalent 21) was used as a curing agent, and 2-ethyl-4-methylimidazole was used as a curing accelerator. Further, silica (“SFP-10—” manufactured by Denki Kagaku Kogyo KK) was used as a filler, and dimethylformamide (DMF) was used as an organic solvent.

[0045] In addition, as a component that is preferentially dissolved and removed by the etching solution in the second surface roughening treatment, a crosslinked elastomer of a butadiene-acrylonitrile copolymer ("ΧΕR-91J: particle size 0" manufactured by JSR Corporation) may be used. .: M or less) and polybutylacetal resin (“6000R” manufactured by Denki Kagaku Kogyo KK).

[Table 1]

Compound torn (parts by mass) Varnish number

one two Three

Phosphorus-containing epoxy resin 82 0 0

Brominated epoxy resin 0 49 49

Cresol nopolak epoxy resin 0 9 9

Dicyanjiad 3 2 2

2-Ethyl 4-methylimidazole 0.1 0.1 0.1 Silica 10 10 10

DMF 0 25 25

Crosslinked elastomer 1 10 10 0

Polyvinyl acetal resin 5 5 0

110.1 110.1 95.1

(Preparation of Pre-Preda)

In this example, three kinds of varnishes shown in Table 1 were used, and as a fibrous base material, Nitto Boseki's "WEA1116" which is 0.08 mm thick glass cloth and 0.04 mm thick glass cloth were used. A certain Nittobo `` WEA1078 '' was used to impregnate the glass cloth with the varnish and glass cloth combinations shown in Table 2 and then dried by heating at 170 ° C with a dryer to obtain semi-cured B. A pre-preda in a stage state was produced.

(Example 1)

Using the varnish "1" and the glass cloth "WEA1116", the printed wiring board was manufactured as follows, using the pre-preparer prepared in the following manner. First, as shown in FIGS. 6 (a) and 6 (b), the pre-predder 30 is placed on the surface of the inner layer substrate 5 on which the inner layer circuit 4 (“R-1566” manufactured by Matsushita Electric Works) has been formed by force. Further, an electrolytic copper foil (“3EC-III” manufactured by Mitsui Kinzoku Co., Ltd., thickness: 18 μm) was laminated as a transfer sheet 8 on the pre-predator 30 and integrally laminated and formed by a multi-stage vacuum press method. Lamination molding was performed by changing the heating and pressing conditions in the following order (1) to (7).

(1) Pressure 0.5MPa (5kgfZcm ² ), hot platen temperature 30. Hold at C for 30 minutes.

(2) Pressure 0.5MPa (5kgfZcm ² ), heating plate temperature increased to 120 ° C. The heating rate is 20 ° CZ min.

(3) Pressure 0.5MPa (5kgfZcm ^2), held for 5 minutes at heating platen temperature 120 ° C. ⁽⁴⁾ Pressure 2.0MPa ^⁽² 0kgfZcm ^2), heating platen temperature 1 ² 〇. Hold at C for ² minutes.

(5) Pressure 2.0MPa (20kgfZcm ² ), heating plate temperature raised to 160 ° C. The heating rate is 3 ° CZ minutes.

(6) Pressure 2.0MPa (20kgfZcm ² ), hot platen temperature 160. Hold at C for 30 minutes.

(7) Pressure 2.0MPa (20kgfZcm ² ), cool the hot platen temperature to below 50 ° C with cooling water.

Next, as shown in FIG. 6 (c), after lamination molding, the transfer sheet 8 was removed by etching to perform a first surface roughening treatment. Further, following the first surface roughening treatment, a second surface roughening treatment was performed. The second roughening treatment was performed in the following order (1) to (3).

(1) The laminate was immersed in Shipley's "Circuposit MLB211" solution at 75 ° C for 6 minutes.

(2) Next, it was immersed for 10 minutes at 80 ° C in Meltex's “Enplate MLB497” solution.

(3) Immerse in “Mentex MLB-791M” solution at 40 ° C for 5 minutes.

Thereafter, after the outer layer circuit 70 was formed by the additive method, after-curing was performed at 170 ° C. for 120 minutes using a drier to form a four-layer print of Example 1 as shown in FIG. 6 (d). A wiring board was obtained. The outer layer circuit 70 was formed by performing electroless copper plating, drying at 120 ° C. for 60 minutes, and further performing electrolytic copper plating. The plating thickness is 20 ± 2 m.

(Example 2)

Example 1 was repeated except that a prepreg prepared using varnish "1" and glass cloth "WEA1078" was used, and a transfer sheet 8 of a peeling type was used in place of the transfer sheet of the etching removal type of the example 1. Similarly, a four-layer printed wiring board of Example 2 was obtained.

As shown in FIG. 5, the transfer sheet 8 used in the present example is a film-like polyethylene terephthalate (PET) 13 having a thickness of 12 m and a 25 μm-thick aluminum接着 Adhered to a foil 15 to form a sheet material 12, then 10% by mass of crushed silica (“FS-20” manufactured by Denki Kagaku Kogyo Co., Ltd.) was blended with polypropylene (PP). It was prepared by applying it to a surface of 12 aluminum foil 15 so as to have a thickness of 2 m.

(Example 3)

A four-layer printed wiring board of Example 3 was obtained in the same manner as in Example 2, except that a pre-preparer manufactured using varnish “2” and glass cloth “WEA1078” was used.

(Example 4) A four-layer printed wiring board of Example 4 was obtained in the same manner as in Example 2 except that a pre-preparer manufactured using varnish “3” and glass cloth “WEA1078” was used.

(Example 5)

As the transfer sheet 8, a four-layer printed wiring board of Example 5 was obtained in the same manner as in Example 2, except that the blending amount of the crushed silica was 20% by mass.

(Comparative Example 1)

A four-layer printed wiring board of Comparative Example 1 was obtained in the same manner as in Example 2, except that a sheet containing no crushed silica was used as the transfer sheet 8.

(Comparative Example 2)

The printed wiring board of Comparative Example 2 was manufactured by the following method. First, as shown in FIGS. 8 (a) and 8 (b), a resin sheet 25 with a protective film 26 and a resin sheet 25 are formed on the surface of an inner substrate 5 of the same kind as that used in Example 1. After being overlapped so as to be in contact with the inner layer substrate 5, they were integrally laminated and formed by a vacuum lamination method.

[0058] The resin film 25 with the protective film 26 used in this comparative example was formed on a polyethylene terephthalate (PET) film having a thickness of 40 m using a multi-coater ("M400" manufactured by Hirano Tecseed Co., Ltd.). Apply varnish "1" to a thickness of about 60 m, dry it at a temperature of 100 ° C while transporting it at a transport speed of 20 cm Z, and coat the applied surface with polyethylene (PE) with a thickness of 20 m. It was made by coating with a film. The PE film was peeled off before lamination molding.

Next, as shown in FIG. 8 (c), after the protective film 26 was peeled off, an outer layer circuit 70 was formed on the exposed resin sheet using an additive method, and dried at 170 ° C. By performing after-curing for 120 minutes, a four-layer printed wiring board as shown in FIG. 8 (d) was obtained. The outer layer circuit 70 was formed by performing electroless copper plating, drying at 120 ° C. for 60 minutes, and performing electrolytic copper plating. The plating thickness is 20 ± 2 m.

[0060] Regarding the printed wiring boards of Examples 1 to 5 and Comparative Examples 1 and 2 produced as described above, (1) peel strength of plating, (2) measurement of elastic modulus, and (3) insulation reliability evaluated. In addition, the surface roughness (Rz and Ra) of the substrate before plating was measured with an ultra-depth surface shape measuring microscope VK-8500 manufactured by Keyence Corporation. [0061] (1) Peel strength

The peel strength of the outer layer circuit 70 (copper plating width 10 mm) was measured. The number of evaluation samples (n) was set to 5, and the average value was defined as the peel strength. Table 2 shows the results.

[0062] (2) Elastic modulus

Eight pre-predas used in each example were superimposed, and a laminate obtained by laminating them was used as a sample for elastic modulus evaluation. In Comparative Example 2, eight resin films 24 each having the protective film 26 peeled off S were superposed, and a laminate obtained by laminating the resin films 24 was used as an evaluation sample. Using these samples, the elastic modulus (25 ° C.) was measured by the DMA method. Table 2 shows the results.

[0063] (3) Insulation reliability

An insulation reliability test was performed by the following method. First, by applying a direct current of 20 V to the printed wiring board in an atmosphere of a temperature of 130 ° C. and a relative humidity of 85%, the resistance value before the test of the insulating layer formed by the pre-preda or the resin sheet was measured. Next, the printed wiring board was left for 150 hours while applying a DC voltage of 20 V in an atmosphere of a temperature of 130 ° CZ and a relative humidity of 85%, and the resistance value of the insulating layer after the test was measured by applying a DC voltage of 20 V. . When the ratio of the resistance after the test to the resistance before the test is less than 50%, `` X '', when the ratio is 50% or more, `` 〇 '', the number of evaluation samples is 3, and the insulation reliability is determined by the number of 〇. Was determined. Table 2 shows the results.

[Table 2]

Example Comparative example

1 2 3 4 5 1 2 Varnish number 1 1 2 3 1 1 1 Glass cloth (WEA No.) 1116 1078 1078 1078 1078 1078 ... Lamination method of insulating layer Multi-stage vacuum press Vacuum la 5 Nominator Elastic modulus (25 ° C) (kgf / mm ² ) 1189 908 903 973 899 903 522

(MPa) 11660 8904 8855 9610 8810 8855 5116 Peel strength (kgf / cm) 0.88 0.85 0.86 0.68 0.89 0.59 0.59 (n = 5 average) (N / cm) 8.6 8.3 8.4 6.7 8.7 5.8 5.8 5.8 Surface roughness Rz (μιη) 1 1.9 7.2 9.7 3.9 17.1 2.7 2.6

(After the second roughening treatment) Ra (μπι) 0.54 0.29 0.46 0.19 1.30 0.08 0.07 Insulation reliability (Test time: 200 hours) 〇〇〇〇〇〇 ΟΟΟ ΟΟΟ XXX 〇〇〇 ΟΧ Χ

[0065] As can be seen from Table 2, the results were compared with Comparative Example 1 in which the first surface roughening treatment was performed and Comparative Example 2 in which the first and second surface roughening treatments were not performed. It can be seen that Examples 1 to 5 in which the first and second surface roughening treatments were performed exhibit high adhesion. In Comparative Example 1, since a sheet containing no crushed silica was used, no irregularities were transferred to the surface of the pre-predator, which is considered to be the cause of the decrease in adhesion. In Comparative Example 2, the rigidity was low because the fibrous base material was not used.

In Example 4, particles preferentially dissolved by the etchant in the second surface roughening treatment were contained in the pre-preda. Therefore, the effect of the second surface roughening treatment on the adhesion was considered. Is slightly lower than in Examples 1-3. In Example 5, since the blending amount of the crushed silica contained in the force transfer sheet 8 with very high adhesion was as large as 20% by mass, the irregularities transferred to the pre-predator became too deep, and Was unable to obtain sufficient insulation reliability. This suggests that in order to improve adhesion and ensure insulation reliability, it is necessary to appropriately determine the amount of unevenness (surface roughness) transferred to the pre-preda according to the thickness of the pre-preda. are doing. In the present invention, since it is relatively easy to control the surface roughness of the transfer sheet in the first roughening treatment and the size of the particles to be dissolved in the second roughening treatment, It can flexibly cope with the production of printed wiring boards with different thicknesses and can reliably reproduce the optimum unevenness on the pre-predator surface with high reliability.

As described above, according to the method for manufacturing a wiring board of the present invention, it is possible to relatively easily provide an optimum surface state with good reproducibility and high adhesion and insulation reliability. Therefore, it is expected that the technique for manufacturing a printed wiring board, which tends to be thinner in recent years, has high applicability.

Claims

The scope of the claims

[1] a first roughening treatment for physically roughening the surface of the substrate mainly comprising the electrically insulating resin composition;

A second surface roughening process for chemically roughening the surface of the substrate roughened by the first surface roughening process by using an etchant;

Forming a conductive layer on the substrate surface roughened by the second surface roughening treatment.

[2] In the production method according to claim 1, the substrate is a pre-preda prepared by impregnating a fibrous base material with an electrically insulating resin composition.

[3] In the manufacturing method according to claim 1, in the first surface roughening treatment, a sheet having an uneven surface with a predetermined surface roughness is integrally formed with the substrate so that the uneven surface is transferred to the substrate surface. And removing the sheet from the substrate to obtain a physically roughened substrate surface.

[4] In the production method according to claim 3, the sheet is produced by applying a release agent containing an inorganic filler to the surface of the sheet material.

[5] In the manufacturing method according to claim 1, the first and second roughening treatments are performed with a surface roughness of 1 力 (10-point average roughness) of 3 to 15! ^ And Ra (arithmetic mean roughness) is implemented to be 0.1 ~ 1.0 / ζπι.

[6] The manufacturing method according to claim 1, wherein the substrate includes particles made of a material dispersed in the electrically insulating resin composition and preferentially dissolved by the etching solution, and a second surface roughening treatment is performed. Is carried out by preferentially dissolving, with the etching solution, the particles distributed near the surface of the substrate roughened by the first roughening treatment.

[7] In the production method according to claim 6, the material constituting the particles includes a crosslinked elastomer of a butadiene-attali-mouth-tolyl copolymer and a polybutylacetal resin.

[8] In the manufacturing method according to claim 1, the conductive layer is formed on a substrate surface roughened by a second roughening process by an additive method.

[9] In the manufacturing method according to claim 1, the inner layer material having a circuit formed on the surface is so contacted that the circuit is in contact with the surface of the substrate opposite to the surface subjected to the first roughening treatment. , With the above substrate Including a joining step.

[10] A first roughening treatment for physically roughening the surface of the substrate containing the electrically insulating resin composition, and the surface of the substrate roughened by the first roughening step And a step of forming a conductive layer on the substrate surface roughened by the second surface roughening treatment by chemically roughening the surface by using an etchant. The wiring board is provided so that a material constituting the conductive layer bites into the unevenness of the surface roughened by the first roughening treatment and the second roughening treatment. It has an interface structure between the formed conductive layer and the substrate.

11. The wiring substrate according to claim 10, wherein the first surface-roughening treatment integrally forms a sheet having an uneven surface with a predetermined surface roughness such that the uneven surface is transferred to the substrate surface. And removing the sheet from the substrate to obtain a physically roughened substrate surface.

12. The wiring substrate according to claim 10, wherein the substrate includes particles made of a material dispersed in the electrically insulating resin composition and preferentially dissolved by the etching solution, and the second surface roughening treatment. Is carried out by preferentially dissolving, with the etching solution, the particles distributed near the surface of the substrate roughened in the first roughening step.

[13] In the wiring board according to claim 10, the substrate surface roughened by the first and second roughening treatments is 1¾ (10-point average roughness) of 3 to 15! It has a surface roughness of 0.1 to 1.0 m in Ra (arithmetic mean roughness).