JPWO2005104638A1 - Wiring board and manufacturing method thereof - Google Patents

Abstract

Provided are a wiring substrate having high adhesion between a substrate and a conductive layer, and a method for manufacturing the wiring substrate. A transfer sheet having a concavo-convex surface with a predetermined surface roughness is formed integrally with the substrate so that the concavo-convex surface is transferred to the substrate surface, and then the transfer sheet is removed from the substrate to perform the first roughening treatment. . Next, a second roughening process is performed in which the substrate surface roughened by the first roughening process is chemically roughened by using an etchant. Next, a conductive layer is formed on the substrate surface that has been subjected to the first and second roughening treatments, preferably by an additive method.

Description

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

  Along with the recent reduction in size and weight of electronic / electrical devices, printed wiring boards incorporated therein tend to be thinner, and various improvements have been attempted in their manufacturing methods.

  For example, Japanese Laid-Open Patent Publication No. 5-136575 proposes a method for manufacturing a multilayer printed board that can reduce the thickness of the multilayer printed board and reduce warping and twisting during component mounting. In this method, as shown in FIGS. 8A and 8B, after a resin film 25 with a protective film 26 is disposed on the surface of the inner layer base material 5 having a predetermined inner layer circuit 4, a laminate is formed. 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 the outer layer circuit 70 is formed on the exposed resin film 25 using an additive method. Thereby, a multilayer printed board as shown in FIG. 8D is obtained. In the figure, reference numerals 71 and 72 are through-hole plating and blind via holes for electrically connecting the inner layer circuit 4 and the outer layer circuit 70.

  In the multilayer printed board manufactured in this way, the insulating layer can be formed thin by using the resin film 25, and the fine pattern can be formed by adopting the additive method. However, there is still room for improvement in the adhesion of the outer layer circuit 70, and there is another problem that the use of the resin film 25 causes a reduction in rigidity of the multilayer printed board.

  Therefore, a main object of the present invention is to provide a method of manufacturing a wiring board that can achieve high adhesion strength of a conductive layer and can flexibly cope with requests for improvement in insulation reliability and improvement in rigidity. is there.

  That is, the manufacturing method of the present invention is roughened by the first roughening treatment and the first roughening treatment, which physically roughen the surface of the substrate mainly composed of the electrically insulating resin composition. A second roughening treatment for chemically roughening the surface of the substrate obtained by using an etching solution, and a step of forming a conductive layer on the roughened substrate surface by the second roughening treatment. It is characterized by that.

  A further object of the present invention is to provide a wiring board obtained by the above-described manufacturing method, in which the material constituting the conductive layer is made of a first roughening treatment and a second roughening. It has an interface structure between the conductive layer and the substrate formed so as to bite into the unevenness of the surface roughened by the treatment.

  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 held on the substrate by the anchor effect of the conductive layer material on the unevenness of the substrate surface. High adhesion of the conductive layer can be achieved.

  In the above-described invention, the first roughening treatment includes a step of integrally forming a sheet having an uneven surface having a predetermined surface roughness with the substrate so that the uneven surface is transferred to the substrate surface, and removing the sheet from the substrate. It is preferable to include a step of obtaining a physically roughened substrate surface. In particular, the sheet is made of a metal such as copper, and the sheet is removed by etching to obtain a physically roughed substrate surface, or a sheet coated with a release agent containing an inorganic filler. It is preferred to employ any one of the steps of using and peeling the sheet from the substrate to obtain a physically roughened substrate surface.

  In the case of adopting the first roughening treatment described above, the high uniformity of the treatment effect is more reliable than the case of performing the roughening treatment by a technique such as grinding or sandblasting. Can be reproduced well.

  In the above-described invention, 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 roughening treatment is performed by the first roughening treatment. It is preferable to carry out by preferentially dissolving the particles distributed near the surface of the roughened substrate with an etching solution.

  In this case, by changing the blending amount, shape, and dimensions of the dispersed particles, the amount, shape, and size of the unevenness introduced to the substrate surface by the second roughening treatment can be controlled. When implemented in combination with the first roughening treatment, even when a thin printed wiring board is manufactured, the optimum roughening is achieved from the viewpoints of improving the adhesion of the conductive layer and ensuring electrical insulation. Processing can be carried out efficiently.

  The first and second roughening treatments are performed so that 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 that When the thickness of a substrate such as a prepreg produced by impregnating a fibrous base material with an electrically insulating resin composition is thin, the depth of the wiring substrate when Rz exceeds 15 μm or Ra exceeds 1.0 μm Insulation reliability in the direction may be reduced. Also, when Rz is less than 3 μm or Ra is less than 0.1 μm, the effect of improving the adhesion strength of the conductive layer tends to be small.

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

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

(A)-(e) is a schematic process drawing of the two-step roughening process concerning preferable embodiment of this invention. It is a SEM photograph of the substrate surface before the first roughening treatment. It is a SEM photograph of the substrate surface after the first roughening treatment. It is a SEM photograph of the substrate surface after the 2nd roughening process. It is a schematic sectional drawing which shows an example of the transfer sheet used for a 1st roughening process. (A)-(d) is a schematic process drawing which shows the manufacturing method of the printed wiring board concerning preferable embodiment of this invention. (A)-(g) is a schematic process drawing which shows the manufacturing method of another printed wiring board concerning preferable embodiment of this invention. (A)-(d) is a schematic process drawing which shows the manufacturing method of the conventional printed wiring board.

  Hereinafter, a wiring board and a manufacturing method thereof according to the present invention will be described in detail based on preferred embodiments with reference to the accompanying drawings.

  The board | substrate used for this invention contains an electrically insulating resin composition as the main component. Although this resin composition is not specifically limited, For example, epoxy resins, such as a phosphorus containing epoxy resin, a brominated epoxy resin, a cresol novolak type epoxy resin, can be used. The resin composition includes a curing agent such as dicyandiamide, a curing accelerator such as 2-ethyl-4-methylimidazole, and a filler such as silica and an organic solvent such as dimethylformamide (DMF) as necessary. May be blended.

  Moreover, when using as a board | substrate the prepreg produced by impregnating a fibrous base material with an electrically insulating resin composition, the rigidity of a printed wiring board can be obtained highly with a fibrous base material. Moreover, 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) manufactured by Nittobo Co., Ltd., “WEA1078” (a glass cloth having a thickness of 0.04 mm), or the like can be used. In addition, although the thickness of a fibrous base material is suitably set according to the thickness dimension of a board | substrate, 0.019 mm (19 micrometers) can be set as a minimum of the thickness, for example. After impregnating the fibrous base material with the resin composition, the resulting impregnated body is heated and dried with a dryer to obtain a prepreg in a semi-cured B-stage state.

  Further, in order to effectively carry out the second roughening treatment described later, particles made of a material preferentially dissolved by the etching solution used in the second roughening treatment are dispersed in the resin composition. Is preferred. FIG. 1A shows a flat surface state of the substrate 1 before the first roughening treatment, and the particles 20 are uniformly dispersed in the substrate 1. Moreover, the SEM photograph of FIG. 2 shows that the substrate surface before the first roughening treatment is flat.

  Next, the 1st roughening process which physically roughens the surface of the board | substrate 1 is implemented. As the first roughening treatment, a transfer sheet 8 having a concavo-convex surface having a predetermined surface roughness is integrally formed with the substrate so that the concavo-convex surface is transferred to the surface of the substrate 1 in view of the uniformity of processing efficiency and processing effect. It is preferable to include a step (FIG. 1 (b)) of performing a step of obtaining a physically roughened surface of the substrate by removing the transfer sheet 8 from the substrate 1 (FIG. 1 (c)). Specifically, there are a method in which the substrate 1 and the transfer sheet 8 are integrally formed and then the transfer sheet is etched and removed, and a method in which the transfer sheet is peeled and removed.

  When the transfer sheet 8 is dissolved and removed to roughen the substrate, a release metal foil such as an electrolytic copper foil can be used as the transfer sheet 8. In this case, the surface of the electrolytic copper foil joined to the substrate 1 preferably has 4 to 12 μm Rz (10-point average roughness) and 0.3 to 0.7 m Ra (arithmetic average roughness). The surface roughness of the transfer sheet is transferred to the substrate 1. An existing copper etching solution is used for dissolving the transfer sheet.

  Moreover, when peeling the transfer sheet 8 and roughening the board | substrate 1, a transfer sheet can be produced by apply | coating the mold release agent containing an inorganic filler to a sheet material, for example. 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 polypropylene (PP) or the like is produced. The transfer sheet 8 can be produced by blending 5 to 15% by mass of the inorganic filler 10 such as crushed silica with the release agent 11 and applying this blend 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 10 μm. Moreover, the surface which apply | coated the mold release agent 11 containing the inorganic filler 10 may have Rz (10 point average roughness) of 4-12 micrometers, and Ra (arithmetic average roughness) of 0.3-0.7 m. Preferably, irregularities on this surface are transferred to the substrate surface.

  FIG. 1B shows a state in which the transfer sheet 8 is integrally formed on the surface of the substrate 1, and FIG. 1C shows the unevenness on the surface of the transfer sheet by peeling the transfer sheet. It shows how it is transferred to the surface. FIG. 3 is an SEM photograph of the substrate surface after the transfer sheet is peeled off. It can be seen that irregularities of several microns are uniformly formed on the substrate surface. According to the first roughening treatment using the transfer sheet 8 described above, it is possible to achieve an excellent adhesion improving effect and its reliability compared to the case of roughening by grinding or sandblasting. That is, when the substrate surface is roughened by grinding, the substrate material in the vicinity of the surface is crushed, so even if a conductive layer is formed on it, the conductive layer is peeled off together with the crushed substrate material. There is a risk that the adhesion improvement as expected cannot be obtained. In addition, when the surface of the substrate is mechanically roughened by sandblasting or the like, the sprayed particles may remain on the surface of the substrate and adversely affect the adhesion of the conductive layer formed thereafter. Furthermore, the roughening process by grinding or sandblasting tends to cause variations in processing effects.

  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 easily controlled, and even when the substrate processing area is large, the substrate There is an advantage that a uniform treatment effect can be achieved throughout. For this reason, it is particularly preferable to perform the first roughening treatment of the present invention by removing the transfer sheet 8 from the substrate 1.

  Next, a second roughening process is performed in which the substrate surface roughened by the first roughening process is chemically roughened by using an etchant. As the second roughening treatment, a substrate in which the particles 20 are dispersed inside is used, and the particles 20 distributed near the surface of the substrate roughened by the first roughening treatment are given priority by the etching solution. It is particularly preferable to carry out by dissolving the solution.

  As the particles 20 that are preferentially dissolved in the etching solution, for example, a crosslinked elastomer such as a butadiene-acrylonitrile copolymer, polyvinyl acetal, or the like can be used. Although the compounding quantity of particle | grains can be set suitably, for example, it is preferable that the compounding quantity of a particle component shall be 1-20 mass% with respect to the resin composition whole quantity. Moreover, the average particle diameter of the particle | grains 20 melt | dissolved by a 2nd roughening process is 0.1-2 micrometers from a viewpoint of forming fine unevenness | corrugation effectively in the surface to which the 1st roughening process was performed. It is preferable to be in the range.

  As an etching solution for dissolving the particles 20, an etching solution containing at least one of an acid and an oxidizing agent can be used. For example, “Circuposit MLB211” manufactured by Shipley Co., “Enplate MLB497” manufactured by Meltex, “ A combination of three types of “enplate MLB-791M” can be used as an etching solution. Here, “Circuposit MLB211” has an ethylene glycol aqueous solution as a main component and has a function of swelling the resin. “Emplate MLB497” is mainly composed of a potassium permanganate aqueous solution (oxidant) and a potassium hydroxide aqueous solution, and has a function of dissolving a resin, particularly a dissolved component. Permanganates such as potassium permanganate act as strong oxidants under basic conditions. As a solution having a function of dissolving the resin, a solution mainly composed of a sodium permanganate aqueous solution (oxidant) and a sodium hydroxide aqueous solution may be used. “Enplate MLB-791M” is mainly composed of a sulfuric acid aqueous solution (acid) and a hydrogen peroxide aqueous solution, and has a function of neutralizing a basic state.

  When the second roughening treatment is performed, the particles 20 existing in the vicinity of the uneven surface of the substrate 1 transferred by the first roughening treatment are preferentially dissolved by the etching solution, as shown in FIG. Further finer irregularities are formed on the irregular surface of the substrate. FIG. 4 is an SEM photograph of the substrate surface after the second roughening process is performed on the first roughened surface of FIG. 3, and as is apparent from the comparison between FIG. 3 and FIG. A number of fine irregularities are formed by the second roughening process on each of the irregularities formed by the first roughening process. Thus, the surface area of a board | substrate can be increased notably by implementation of the 2nd roughening process following a 1st roughening process. In addition, when only the 2nd roughening process was implemented to the board | substrate which has a flat surface, 1-5 micrometers Rz (10-point average roughness) and 0.03-0.4m Ra ( As described above, Rz (10-point average roughness) and 0.3 to 0.7 m Ra are preferably formed. When combined with the first roughening treatment for forming relatively rough (arithmetic average roughness), the surface roughness after the second roughening treatment is expressed as Rz (10-point average roughness). 3) to 15 μm and Ra (arithmetic mean roughness) to 0.1 to 1.0 μm.

  Next, the 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 is formed by the material constituting the conductive layer biting into the irregularities on the surface roughened by the first roughening treatment and the second roughening treatment (anchor effect). To form). According to the interface structure between the conductive layer 7 and the substrate 1 obtained in this manner, the contact area between the conductive layer and the substrate can be remarkably increased, and the surface of the substrate of the conductive layer material can be increased. The conductive layer is firmly held on the substrate by the anchor effect on the unevenness. 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, but it is particularly preferable to employ an additive method as described later. The additive method includes a full additive method and a semi-additive method, and any method may be used in the present invention.

  As described above, according to the present invention, the surface of the substrate is physically roughened by transferring the unevenness of the transfer sheet to the base material in particular by the combination of the physical roughening treatment and the chemical roughening treatment. A combination of the first roughening treatment and the second roughening treatment in which the particles dispersed inside the substrate are preferentially etched away and the substrate surface is chemically roughened, so that the gap between the conductive layer and the substrate is reduced. High adhesion can be realized with high reliability.

  Next, an example of the manufacturing method of the multilayer printed wiring board of this invention is demonstrated concretely.

  As shown in FIG. 6A, a prepreg 30 produced by impregnating a fibrous base material 3 with an electrically insulating resin composition 2 on an inner layer substrate 5 on which predetermined inner layer circuits 4 are formed in advance on both sides. Further, after the transfer sheet 8 is arranged on the prepreg 30, as shown in FIG. 6B, these are integrally laminated and formed by a forming method such as a multistage vacuum press. The inner layer substrate 5 can be manufactured, for example, by laminating and forming a necessary number of prepregs 30 and the inner layer circuit 4 can be formed by an additive method or a subtractive method. Moreover, you may form a circuit in laminated boards, such as a commercially available copper clad laminated board. Alternatively, the prepreg 30 may be disposed only on one side of the inner layer substrate 5 and laminated. Prior to the lamination molding, the inner layer circuit 4 of the inner layer substrate 5 may be subjected to a roughening process such as a black oxidation process (blackening process).

  Next, as shown in FIG. 6C, by removing the transfer sheet 8, the insulating layer 6 is formed by the prepreg 30, and at the same time, the unevenness of the transfer sheet is transferred to the prepreg surface. As described above, since the roughening treatment of the insulating layer can be performed simultaneously with the formation of the insulating layer, the manufacturing efficiency can be improved. The roughening treatment by the transfer sheet 8 is intended to increase the surface area of the prepreg 30 by the unevenness formed on the prepreg 30 (insulating layer 6), and the depth of the formed unevenness is , Determined according to the thickness of the prepreg. For example, when a thin prepreg is used to reduce the thickness of the wiring board, the insulation reliability in the thickness direction may be lowered if the unevenness formed by the roughening process is excessively deep. For example, when the surface is roughened by sandblasting or the like, the thickness of the prepreg may be reduced when the processing time is extended, and there may be a problem in insulation reliability. By simply using a transfer sheet with a rough surface, the prepreg with the same surface roughness can be provided with good reproducibility, quality control becomes easy, and defects that occur during the pretreatment process are eliminated. It can be reduced to improve the yield.

  Next, a second roughening process is performed using the etching solution. The second roughening treatment can be performed by immersing the laminate shown in FIG. 6C 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 to 40 to 90 ° C., and the immersion time can be set to 1 to 30 minutes. In addition, when using the above-mentioned three types of “Circuposit MLB211”, “Enplate MLB497”, and “Enplate MLB-791M” as an etching solution as a set, first, the laminate is “Circuposit MLB211”. And swell the resin, then immerse the laminate in “Enplate MLB497” to dissolve the resin, and finally immerse the laminate in “Enplate MLB-791M” to change the basic state. By neutralizing, the second roughening treatment can be performed. In this way, it is ideal to perform the second roughening process by etching after the first roughening process by using the transfer sheet, but the first roughening process is performed by a method other than the transfer sheet. It does not exclude performing the second roughening process after the operation.

  Thereafter, the outer layer circuit 70 is formed on the surface of the first and second roughened insulating layers 6 by an additive method, and the inner layer circuit 4 and the outer layer circuit 70 on the insulating layer 6 are connected as necessary. Therefore, by forming the through-hole plating 71, 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, but the present invention is not limited to this, and the above-mentioned four-layer board is used as the inner-layer substrate 5 and the multilayer is further processed through the same steps. The printed wiring board which consists of can be manufactured.

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

  First, in the laminate shown in FIG. 7A subjected to the second roughening treatment, as shown in FIG. 7B, through holes 50 for forming through-hole plating and blind via holes are formed. A hole 52 reaching the inner layer circuit 4 is formed by a drill or the like. The laminate shown in FIG. 7A can be manufactured in the same manner as in FIG.

  Next, as shown in FIG.7 (c), the plating layer 40 is formed in the surface of the insulating layer 6 comprised with the prepreg 30 by performing electroless plating. Next, as shown in FIG. 7D, a plating resist 60 is formed in a portion where the formation of the outer layer circuit 70 is not required. Furthermore, as shown in FIG. 7E, an electrolytic plating process such as electrolytic copper plating is performed to form an electrolytic plating layer 43 in a portion where the plating resist 60 is not formed.

  Next, as shown in FIG. 7 (f), after the electroless plating 40 is exposed by removing the plating resist 60, this is removed by quick etching (flash etching), as shown in FIG. 7 (g). A multilayer printed wiring board on which such an outer layer circuit 70 is formed can be obtained. By forming the electroless plating 40 and the electrolytic plating 43 on the inner surfaces of the through hole 50 and the hole 52, a through hole plating 71 and a blind via hole 72 for electrically connecting the inner layer circuit 4 and the outer layer circuit 70 are formed. . In addition, after cure is performed as appropriate.

Hereinafter, the present invention will be specifically described based on examples.
<Preparation of varnish>
In this example, the components were mixed in the blending amounts as shown in Table 1 to prepare three types of varnishes “1” to “3”.
The phosphorus-containing epoxy resin used to prepare varnish “1” was obtained as follows. First, a stirrer and a condenser tube were attached to a three-necked flask having a capacity of 300 ml, and then a predetermined amount of dimethylformamide (DMF) and methoxypropanol (MP) was added to the flask. "Epicron 850S" 53 parts by mass and "Epicron N690" 13 parts by mass) were added. Epoxy equivalents of “Epicron 850S” and “Epicron N690” are 190 and 220, respectively.

  Then, when the obtained mixture was heated in an oil bath and reached 80 ° C., 16 parts by mass of a phosphorus compound (manufactured by Sanko Chemical Co., Ltd.) represented by the following [Chemical Formula 1] was added and further heated. When the temperature reached 100 ° C., triphenylphosphine was added at a rate of 0.2 mass% with respect to the total solid content, and the phosphorus compound and the epoxy resin were reacted. Then, when the predetermined epoxy equivalent was reached, the reaction was terminated to obtain a phosphorus-containing epoxy resin solution. The progress of the reaction was confirmed by measuring the epoxy equivalent based on JIS K 7236-1995.

  The brominated epoxy resin used for the preparation of varnishes “2” and “3” is “YDB-500” manufactured by Toto Kasei Co., Ltd., and the cresol novolac type epoxy resin is “Epicron N690” manufactured by Dainippon Ink & Chemicals, Inc. is there. Dicyandiamide (molecular weight 84, theoretically active hydrogen equivalent 21) was used as the curing agent, and 2-ethyl-4-methylimidazole was used as the curing accelerator. Further, silica (“SFP-10X” manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as a filler, and dimethylformamide (DMF) was used as an organic solvent.

  In addition, as a component that is preferentially dissolved and removed by the etching solution in the second roughening treatment, a crosslinked elastomer of a butadiene-acrylonitrile copolymer (“XER-91” manufactured by JSR Corporation: particle size of 0.1 μm or less) and A polyvinyl acetal resin (“6000R” manufactured by Denki Kagaku Kogyo Co., Ltd.) was used.

(Preparation of prepreg)
In this example, the three types of varnish shown in Table 1 and the fibrous base material are “WEA1116” manufactured by Nittobo Co., Ltd., which is a glass cloth having a thickness of 0.08 mm, and a glass cloth having a thickness of 0.04 mm. Using “WEA1078” manufactured by Nittobo Co., Ltd., impregnating the glass cloth with the varnish and glass cloth shown in Table 2, and then drying by heating at 170 ° C. with a dryer, it is in a semi-cured B stage state. A prepreg was prepared.

(Example 1)
Using a prepreg produced using varnish “1” and glass cloth “WEA1116”, a printed wiring board was produced as follows. First, as shown in FIGS. 6A and 6B, a prepreg 30 is disposed on the surface of the inner layer substrate 5 on which the inner layer circuit 4 (“R-1566” manufactured by Matsushita Electric Works) is formed in advance. An electrolytic copper foil (“3EC-III” manufactured by Mitsui Kinzoku Co., Ltd., thickness: 18 μm) as a transfer sheet 8 was stacked on 30 and laminated and formed integrally by a multistage vacuum press method. Lamination molding was performed by changing the heating and pressing conditions in the following order (1) to (7).
(1) Hold at a pressure of 0.5 MPa (5 kgf / cm ² ) and a hot platen temperature of 30 ° C. for 30 minutes.
(2) The pressure was raised to 0.5 MPa (5 kgf / cm ² ) and the hot platen temperature was raised to 120 ° C. The heating rate is 20 ° C / min.
(3) Hold at a pressure of 0.5 MPa (5 kgf / cm ² ) and a hot platen temperature of 120 ° C. for 5 minutes.
(4) Holding at a pressure of 2.0 MPa (20 kgf / cm ² ) and a hot platen temperature of 120 ° C. for 20 minutes.
(5) The pressure is 2.0 MPa (20 kgf / cm ² ) and the hot platen temperature is raised to 160 ° C. The heating rate is 3 ° C / min.
(6) Hold at a pressure of 2.0 MPa (20 kgf / cm ² ) and a hot platen temperature of 160 ° C. for 30 minutes.
(7) Cooling with cooling water at a pressure of 2.0 MPa (20 kgf / cm ² ) and a hot platen temperature of 50 ° C. or lower.

Next, as shown in FIG.6 (c), after lamination | stacking shaping | molding, the 1st roughening process was performed by removing the transfer sheet 8 by an etching. Furthermore, the 2nd roughening process was performed following the 1st roughening process. The second surface roughening treatment was performed in the following order (1) to (3).
(1) The laminate is dipped in “Circuposit MLB211” solution manufactured by Shipley Co., Ltd. at 75 ° C. for 6 minutes.
(2) Next, it was immersed in the “Emplate MLB497” solution manufactured by Meltex for 10 minutes at 80 ° C.
(3) Immerse in “Emplate MLB-791M” manufactured by Meltex for 5 minutes at 40 ° C.

  Then, after forming the outer layer circuit 70 by an additive method, aftercuring was performed at 170 ° C. for 120 minutes with a dryer, a four-layer printed wiring board of Example 1 as shown in FIG. 6D was obtained. The outer layer circuit 70 was formed by performing an electroless copper plating process, drying at 120 ° C. for 60 minutes, and further performing an electrolytic copper plating process. The plating thickness is 20 ± 2 μm.

(Example 2)
Example 1 except that a prepreg produced using varnish “1” and glass cloth “WEA1078” was used, and a peel-off type transfer sheet 8 was used instead of the etching-removed type transfer sheet of 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 this example is a sheet obtained by bonding a film-like polyethylene terephthalate (PET) 13 having a thickness of 12 μm to an aluminum foil 15 having a thickness of 25 μm with a dry adhesive 14. A material 12 is prepared, and then 10% by mass of crushed silica (“FS-20” manufactured by Denki Kagaku Kogyo Co., Ltd.) is blended with polypropylene (PP). Was prepared by coating so as to be 2 μm.

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

Example 4
A 4-layer printed wiring board of Example 4 was obtained in the same manner as in Example 2 except that a prepreg produced 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 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 produced by the following method. First, as shown in FIGS. 8A and 8B, the resin sheet 25 with the protective film 26 is provided on the surface of the same inner layer substrate 5 used in Example 1, and the surface of the resin sheet 25 is provided on the inner layer substrate 5. After overlapping so as to be in contact, they were integrally laminated by a vacuum laminating method.

  The resin film 25 with the protective film 26 used in this comparative example was varnished to a polyethylene terephthalate (PET) film having a thickness of 40 μm using a multi coater (“M400” manufactured by Hirano Techseed Co., Ltd.). “1” was applied, dried at a temperature of 100 ° C. while being transported at a transport speed of 20 cm / min, and further coated with a polyethylene (PE) film having a thickness of 20 μm. The PE film was peeled off before lamination molding.

  Next, as shown in FIG. 8C, after the protective film 26 is peeled off, the outer layer circuit 70 is formed on the exposed resin sheet using an additive method, and after-curing is performed at 170 ° C. for 120 minutes using a dryer. As a result, a four-layer printed wiring board as shown in FIG. 8D was obtained. The outer layer circuit 70 was formed by performing an electroless copper plating process, drying at 120 ° C. for 60 minutes, and further performing an electrolytic copper plating process. The plating thickness is 20 ± 2 μm.

  Regarding the printed wiring boards of Examples 1 to 5 and Comparative Examples 1 and 2 prepared as described above, (1) Peel strength of plating, (2) Elastic modulus measurement, and (3) Insulation reliability were evaluated. Further, the surface roughness (Rz and Ra) of the substrate before plating was measured with an ultra-deep surface shape measuring microscope VK-8500 manufactured by Keyence Corporation.

(1) Peel strength The peel strength of the outer layer circuit 70 (copper plating width 10 mm) was measured. The evaluation sample number (n) was 5, and the average value was defined as the peel strength. The results are shown in Table 2.

(2) Elastic Modulus Eight prepregs used in each example were stacked and laminated to form a sample for elastic modulus evaluation. In Comparative Example 2, eight resin films 24 from which the protective film 26 was peeled were stacked, and those obtained by lamination molding were used as samples for evaluation. Using these samples, the elastic modulus (25 ° C.) was measured by the DMA method. The results are shown in Table 2.

(3) Insulation reliability An insulation reliability test was performed by the following method. First, the resistance value before the test of the insulating layer formed of a prepreg or a resin sheet was measured by applying a direct current of 20 V to the printed wiring board in an atmosphere at a temperature of 130 ° C./85% relative humidity. Next, this printed wiring board was allowed to stand for 150 hours while applying DC 20V in an atmosphere of 130 ° C./85% relative humidity, and then the resistance value after the test of the insulating layer was measured by applying DC 20V. . And, the ratio of the resistance value after the test to the resistance value before the test is less than 50% as “×”, 50% or more as “◯”, the number of evaluation samples as 3, and the insulation reliability by the number of ○. Judged. The results are shown in Table 2.

  As can be seen from the results in Table 2, the first and second roughened surfaces are compared with Comparative Example 1 in which the first roughening treatment is not performed and in Comparative Example 2 in which the first and second roughening treatments are not performed. It turns out that Examples 1-5 by which the chemical conversion process was implemented show high adhesiveness. In Comparative Example 1, since a sheet containing no crushed silica was used, the unevenness was not transferred to the prepreg surface, which is considered to be a cause of a decrease in adhesion. Moreover, in the comparative example 2, since the fibrous base material is not used, rigidity is also low.

  In Example 4, since the prepreg does not contain particles that are preferentially dissolved by the etching solution in the second surface roughening treatment, the effect of the second surface roughening treatment on the adhesiveness of Examples 1 to 3 is achieved. It is slightly lower than the case of. In Example 5, very high adhesion was obtained, but since the blended amount of crushed silica contained in the transfer sheet 8 was as large as 20% by mass, the unevenness transferred to the prepreg became too deep, and the experimental conditions of this time In this case, sufficient insulation reliability could not be obtained. This suggests that the amount of unevenness (surface roughness) transferred to the prepreg must be appropriately determined according to the thickness of the prepreg in order to improve the adhesion and ensure insulation reliability. is doing. In the present invention, it is relatively easy to control the surface roughness of the transfer sheet in the first roughening treatment and the size of the particles dissolved in the second roughening treatment. It is possible to flexibly cope with the manufacture of plates, and to reproduce the optimum irregularities on the prepreg surface with high reliability.

  As described above, according to the method for manufacturing a wiring board of the present invention, an optimum surface state can be provided with high reproducibility and relatively easily in order to achieve high adhesion and insulation reliability. It is also expected as a technology that is highly applicable to a method of manufacturing a printed wiring board that tends to be thin.

Claims (13)

A first roughening treatment for physically roughening a surface of a substrate mainly composed of an electrically insulating resin composition;
A second roughening treatment for chemically roughening the surface of the substrate roughened by the first roughening treatment by using an etchant;
Forming a conductive layer on the surface of the substrate roughened by the second roughening treatment. In the manufacturing method of Claim 1, the said board | substrate is a prepreg produced by impregnating a fibrous base material with an electrically insulating resin composition. The manufacturing method according to claim 1, wherein the first roughening treatment is a step of integrally forming a sheet having a concavo-convex surface having a predetermined surface roughness with a substrate so that the concavo-convex surface is transferred to the substrate surface; Removing the sheet from the substrate to obtain a physically roughened substrate surface. In the manufacturing method of Claim 3, the said sheet | seat is produced by apply | coating the mold release agent containing an inorganic filler to the surface of a sheet | seat material. 2. The manufacturing method according to claim 1, wherein the first and second roughening treatments have a substrate surface roughness of 3 to 15 μm in Rz (10-point average roughness) and 0.1 in Ra (arithmetic average roughness). It is carried out to be ~ 1.0 μm. 2. 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 the second roughening treatment includes the first roughening treatment. This is performed by preferentially dissolving the particles distributed near the surface of the substrate roughened by the surface treatment with the etching solution. 7. The manufacturing method according to claim 6, wherein the material constituting the particles includes a crosslinked elastomer of a butadiene-acrylonitrile copolymer and a polyvinyl acetal resin. 2. The manufacturing method according to claim 1, wherein the conductive layer is formed on a substrate surface roughened by a second roughening treatment by an additive method. 2. The manufacturing method according to claim 1, wherein an inner layer material having a circuit formed on a surface thereof is connected to the substrate so that the circuit contacts a surface of the substrate opposite to a surface on which a first roughening treatment is performed. A step of bonding. A first roughening treatment that physically roughens the surface of the substrate containing the electrically insulating resin composition, and the surface of the substrate roughened by the first roughening step is made of an etching solution. A wiring board obtained by a manufacturing method including a second roughening treatment that is chemically roughened by use, and a step of forming a conductive layer on the surface of the substrate roughened by the second roughening treatment. The wiring board includes a conductive layer and a substrate formed so that the 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 interfacial structure. The wiring board according to claim 10, wherein the first roughening treatment is a step of integrally forming a sheet having a concavo-convex surface having a predetermined surface roughness with the substrate so that the concavo-convex surface is transferred to the substrate surface; Removing the sheet from the substrate to obtain a physically roughened substrate surface. The wiring board according to claim 10, wherein the board includes particles made of a material dispersed in the electrically insulating resin composition and preferentially dissolved by the etching solution, and the second roughening treatment includes the first roughening treatment. This is performed by preferentially dissolving the particles distributed near the surface of the substrate roughened by the surface-forming step with the etching solution. 11. The wiring board according to claim 10, wherein the substrate surface roughened by the first and second roughening treatments has an Rz (10-point average roughness) of 3 to 15 μm and an Ra (arithmetic average roughness) of 0.1. It has a surface roughness of ˜1.0 μm.