JP2005238520A - Prepreg and multilayered printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg excellent in moldability such as circuit filling properties or the like. <P>SOLUTION: The prepreg 1 is formed by impregnating a base material with a resin 3 and drying the impregnated base material. Unevenness 4 is formed on one side or both sides of the prepreg 1 and the curing time of the resin of the part 7 having the unevenness 4 formed thereto at 170°C is shorter than the curing time of the resin of another part 8 by 5-50 sec. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a prepreg as a material for a printed wiring board and a multilayer printed wiring board manufactured using the prepreg.

  A printed wiring board used for electronic / electrical devices is generally manufactured by forming a conductor circuit made of copper foil or the like on one or both sides of a plate-like insulating layer. In recent years, with the demand for miniaturization and high performance of electronic and electrical devices, it has been desired to increase the density of printed wiring boards used in these devices. On the other hand, as a method of ensuring the electrical connection between layers in these printed wiring boards, a through hole by a drill is formed at a desired position of the printed wiring board, and metal is deposited by plating inside thereof, or a conductive paste or the like There is a method of securing the connection between the layers by filling the conductive material. In recent years, the diameters of these through holes have been reduced along with the demand for higher density.

  As one of the methods for achieving higher density of the printed wiring board, there is a manufacturing method of a multilayer printed wiring board by a so-called build-up method in which the occupied area is reduced by multilayering the substrate.

  When manufacturing a multilayer printed wiring board by the build-up method, after drilling a through hole in a board such as a copper-clad laminate, etc., as a method of ensuring electrical continuity between conductor circuits of different layers A method of forming a through via hole (also referred to as a via hole) for electrically connecting conductor circuits of different layers by forming a conductive layer on the inner surface of the through hole and further forming a conductor circuit on both surfaces of the substrate. Has been done. The through-via hole is generally processed using a drill, and a hole having a diameter of about 100 μm is generally processed by a drill.

  In order to achieve further higher density, in recent years, a non-through hole (non-through via hole) is provided between the layers to be electrically connected, and the hole is filled with a conductive material, through which the electrical layer is electrically connected. The construction method that secures the connection is attracting attention. Various construction methods have been proposed so far for securing the connection between the layers through the non-penetrating via hole.

  In order to ensure the conduction between the upper and lower layers through these holes, a method that deposits a conductive substance inside the hole by plating or the like is currently performed.

  In this way, when conducting further multi-layering after securing conduction, there are generally many systems in which multi-layering is performed by placing a prepreg outside the substrate having these holes. Yes.

  In this case, the functions required of the prepreg include the function of forming an insulating layer (circuit filling property) without sticking to the surface layer circuit existing on the surface of the inner layer substrate and leaving a void due to bubbles, and the function of the prepreg. The function of filling non-through holes and through holes with prepreg resin is also required.

  In this case, from the viewpoint of filling the surface layer circuit, it is advantageous that the resin of the prepreg is easy to flow, but from the viewpoint of filling the resin into the hole, the resin flows around the substrate at the time of molding as the resin of the prepreg easily flows. Therefore, there is a tendency that the resin that can be used for filling the hole is reduced and disadvantageous.

As a method for solving these problems, as described in JP-A-8-283433 (Patent Document 1), a method of advancing the degree of curing of only the surface portion of the prepreg has been proposed. The outflow of the resin during molding is prevented, and the productivity of the multilayer printed wiring board is improved.
JP-A-8-283433

  However, in recent years, voids (voids due to bubbles) are easily generated inside the printed wiring board due to further reduction in the diameter of holes and increase in non-through holes. Therefore, the prepreg is required to be more excellent in moldability such as circuit filling than ever.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a multilayer printed wiring board free from prepregs and voids excellent in moldability such as circuit filling properties.

  The prepreg according to claim 1 of the present invention is the prepreg 1 formed by impregnating the base material 2 with the resin 3 and drying it, and the prepreg 1 is provided with irregularities 4 on one or both sides thereof. The curing time at 170 ° C. of the resin 3 in the portion 7 where 4 is formed is shorter than the curing time of the resin 3 in the other portion 8 by 5 to 50 seconds.

  According to a second aspect of the present invention, in the first aspect, the thickness of the portion 7 where the irregularities 4 are formed is 5 to 30% of the total thickness of the prepreg 1, and the depth direction of the concave portions 5 and the convex portions 6 is The height difference is 5 to 40 μm.

  According to a third aspect of the present invention, in the first or second aspect, the interval between the adjacent convex portions 6 and 6 is 30 to 600 μm.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the unevenness 4 is not crushed even when a pressure of less than 2.94 MPa (30 kg / cm ² ) is applied to the surface of the prepreg 1 at a temperature of 150 ° C. or lower. It is characterized by.

  A multilayer printed wiring board according to claim 5 of the present invention has at least one of a through hole 9 and a non-through hole 10 on the surface on which the unevenness 4 of the prepreg 1 according to any one of claims 1 to 4 is formed. The prepreg 1 and the inner layer substrate 11 are laminated and formed opposite to the surface of the inner layer substrate 11 having one side.

  According to the prepreg according to claim 1 of the present invention, an air escape path can be ensured by the gap due to the unevenness, and high moldability such as circuit filling property can be obtained.

  According to invention of Claim 2, the filling property of the resin to a through hole and a non-through hole can be obtained highly.

  According to invention of Claim 3, the filling property of the resin to a through hole and a non-through hole can be obtained further higher.

  According to the invention of claim 4, the unevenness formed on the prepreg at the time of lamination molding is not immediately crushed but gradually crushed. -The communication state with the inside of the non-through hole can be secured.

  According to the multilayer printed wiring board concerning Claim 5 of this invention, the multilayer printed wiring board which does not have a void can be obtained easily.

  Embodiments of the present invention will be described below.

  A prepreg 1 according to the present invention uses a prepreg 12 formed by impregnating a base material 2 with a resin 3 and drying it (hereinafter referred to as “prepreg 12 before forming irregularities”) as shown in FIG. Can be manufactured.

  Although it does not specifically limit as the base material 2 of the prepreg 12 before uneven | corrugated formation, For example, a glass cloth etc. can be used. Specific examples of the glass cloth include “WEA 1078” and “WEA 7628” manufactured by Nitto Boseki Co., Ltd.

  The resin 3 of the prepreg 12 before forming irregularities is not particularly limited. For example, an epoxy resin, an imide resin, a PPO resin, or the like can be used.

  The prepreg 12 before forming the irregularities can be obtained by impregnating the base material 2 with the resin 3 and drying it at 100 to 200 ° C. for 1 to 10 minutes. A commercially available prepreg may be used as it is as the prepreg 12 before forming the unevenness.

  Although the thickness of the prepreg 12 before forming the unevenness is not particularly limited, it can be set to, for example, 20 to 250 μm by selecting the base material 2 having an appropriate thickness and adjusting the amount of impregnation of the resin 3. it can.

  In manufacturing the prepreg 1 according to the present invention using the prepreg 12 before forming the unevenness, as shown in FIG. 1A, a metal plate 14 having the unevenness 13 formed on the surface can be used. . As a specific example of the metal plate 14, an iron plate etc. can be mentioned, for example. In forming the irregularities 13 on the surface of the metal plate 14, for example, etching, polishing, blasting, or the like can be performed. By adjusting the processing conditions, it is possible to adjust the height difference in the depth direction between the concave and convex portions of the concave and convex portions 13 and the interval between adjacent convex portions. The surface on which the unevenness 13 is thus formed (hereinafter referred to as “unevenness forming surface”) is preferably treated with a release agent. As the release agent, for example, a silicone resin release agent or the like can be used. And the metal plate 14 is preheated to 80-150 degreeC, and as shown to Fig.1 (a), the unevenness formation surface of the metal plate 14 is made to oppose the surface of the prepreg 12 before unevenness formation, and both are arrange | positioned.

Next, as shown in FIG.1 (b), the prepreg 12 before uneven | corrugated formation and the metal plate 14 are press-contacted by the pressure of 0.0490-0.196MPa (0.5-2kg / cm < ² >). Thereby, the shape of the unevenness 13 formed on the metal plate 14 is transferred to the surface of the prepreg 12 before forming the unevenness. At the same time, the heat of the metal plate 14 is transmitted to the prepreg 12 before forming the unevenness, and this heat causes the degree of cure of the resin in the portion in contact with the metal plate 14 in the prepreg 12 before forming the unevenness to the resin of other portions (for example, The process proceeds as compared with the degree of curing of the internal resin 3).

After 2 to 15 seconds have elapsed since the press-contact between the prepreg 12 before forming the unevenness and the metal plate 14, the prepreg 1 according to the present invention is obtained by peeling the metal plate 14 as shown in FIG. be able to. Asperities 4 are formed on one surface of the prepreg 1, and the curing time at 170 ° C. of the resin 3 of the portion 7 (hereinafter also referred to as “surface layer 7”) where the unevenness 4 is formed is the other portion. 8 (hereinafter also referred to as “inner layer 8”) is 5 to 50 seconds shorter than the curing time of the resin 3. When the degree of cure of the resin 3 of the surface layer 7 is not advanced as compared with the degree of cure of the resin 3 of the inner layer 8, the surface layer 7 may be heated with a heater or the like after the irregularities 4 are formed. The degree of cure of the resin 3 of the surface layer 7 can be advanced as compared with the degree of cure of the resin of the inner layer 8 by heating the surface layer 7 with a laser. Further, the unevenness 4 formed as described above has a strength that does not collapse even when a pressure of less than 2.94 MPa (30 kg / cm ² ) is applied to the surface of the prepreg 1 at a temperature of 150 ° C. or less. Yes. When pressure is applied at a temperature exceeding 150 ° C. or pressure of 2.94 MPa (30 kg / cm ² ) or more is applied, the unevenness 4 formed on the prepreg 1 is crushed and flattened. In addition, when the uneven | corrugated formation surface of the metal plate 14 is previously processed with a mold release agent as described above, the metal plate 14 can be peeled smoothly and the unevenness 4 of the prepreg 1 is damaged during the peeling. Can be prevented.

  The prepreg 1 according to the present invention can also be manufactured as shown in FIG.

  That is, in this case, as shown in FIG. 2 (a), the two metal plates 14 having the irregularities 13 formed on the surface can be used, and these metal plates 14 are preheated to 80 to 150 ° C. Then, the three members are arranged with the concavo-convex forming surfaces of the respective metal plates 14 facing both surfaces of the prepreg 12 before forming the concavo-convex portions.

Next, as shown in FIG.2 (b), the prepreg 12 before uneven | corrugated formation and the two metal plates 14 are press-contacted by the pressure of 0.0490-0.196MPa (0.5-2kg / cm < ² >). Thereby, the shape of the unevenness | corrugation 13 formed in each metal plate 14 is transcribe | transferred on both surfaces of the prepreg 12 before unevenness | corrugation formation. At the same time, the heat of each metal plate 14 is transmitted to the prepreg 12 before forming the unevenness, and this heat causes the degree of cure of the resin 3 in the portion in contact with the metal plate 14 in the prepreg 12 before forming the unevenness to the resin in the other portions. 3 (e.g., internal resin 3) is hardened compared to the degree of curing.

After 2-15 seconds have passed since the press contact between the prepreg 12 before forming the unevenness and the two metal plates 14, the two metal plates 14 are peeled off as shown in FIG. The prepreg 1 which concerns on can be obtained. Concavities and convexities 4 are formed on both surfaces of the prepreg 1, and the curing time at 170 ° C. of the resin 3 in the portion 7 where the irregularities 4 are formed is 5 times longer than the curing time of the resin 3 in the other portions 8. ~ 50 seconds shorter. When the degree of cure of the resin 3 of the surface layer 7 is not advanced as compared with the degree of cure of the resin 3 of the inner layer 8, the surface layer 7 may be heated with a heater or the like after the irregularities 4 are formed. By heating the surface layer 7 with a laser, the degree of cure of the resin 3 of the surface layer 7 can be advanced compared to the degree of cure of the resin 3 of the inner layer 8. Further, the unevenness 4 formed as described above has a strength that does not collapse even when a pressure of less than 2.94 MPa (30 kg / cm ² ) is applied to the surface of the prepreg 1 at a temperature of 150 ° C. or less. Yes. When pressure is applied at a temperature exceeding 150 ° C. or pressure of 2.94 MPa (30 kg / cm ² ) or more is applied, the unevenness 4 formed on the prepreg 1 is crushed and flattened. In addition, if the uneven | corrugated formation surface of the metal plate 14 is processed with a mold release agent in advance, the metal plate 14 can be peeled smoothly and the unevenness 4 of the prepreg 1 is prevented from being damaged during the peeling. Is something that can be done.

  In the prepreg 1 according to the present invention, the thickness of the portion 7 where the irregularities 4 are formed, the height difference in the depth direction between the concave and convex portions, and the interval between adjacent convex portions are not particularly limited, Each is preferably set to a predetermined value. This will be specifically described below with reference to FIG.

  FIG. 3 (a) shows a prepreg 1 according to the present invention in which irregularities 4 are formed on one surface. In this prepreg 1, the thickness (D) of the portion 7 where the irregularities 4 are formed is prepreg. It is preferable that it is 5-30% of the thickness (T) of 1 whole, and the height difference (D) of the recessed part 5 and the convex part 6 in the depth direction is 5-40 micrometers. As will be described later, the unevenness 4 formed on the prepreg 1 is to secure an air escape path, but when the thickness (D) of the surface layer 7 is smaller than 5% of the total thickness (T) of the prepreg 1, If the thickness (D) of the surface layer 7 is larger than 30% of the total thickness (T) of the prepreg 1, the air will not be able to escape sufficiently. There is a possibility that the surface smoothness of the obtained printed wiring board and the circuit filling property of the resin 3 of the prepreg 1 may be adversely affected. Further, if the height difference (D) in the depth direction between the concave portion 5 and the convex portion 6 is smaller than 5 μm, the air can easily escape and there is a risk that the air cannot be sufficiently released. If the height difference (D) in the depth direction of the convex portion 6 is larger than 40 μm, the surface smoothness of the finally obtained printed wiring board and the circuit filling property of the resin 3 of the prepreg 1 may be adversely affected. . In addition, the height difference (D) of the depth direction of the recessed part 5 and the convex part 6 can be confirmed by observing the cross section of the prepreg 1 with a microscope.

  Moreover, it is preferable that the space | interval (W) between the adjacent convex parts 6 and 6 is 30-600 micrometers. It is technically difficult to form the unevenness 4 so that the interval (W) between the adjacent convex portions 6 and 6 is smaller than 30 μm, and conversely, the interval (W between the adjacent convex portions 6 and 6 ) Is larger than 600 μm, the surface smoothness of the finally obtained printed wiring board may be adversely affected. In addition, the space | interval (W) between the adjacent convex parts 6 and 6 can be confirmed by observing the surface of the prepreg 1 with a microscope.

FIG. 3B shows the prepreg 1 according to the present invention in which the unevenness 4 is formed on both surfaces. In the prepreg 1, the thickness of the portion where the unevenness 4 is formed (D ₁ + D ₂ ). Is 5 to 30% of the total thickness (T) of the prepreg 1, and the height difference (D ₁ and D ₂ ) in the depth direction between the concave portion 5 and the convex portion 6 is preferably 5 to 40 μm. As will be described later, the unevenness 4 formed on the prepreg 1 secures an air escape path, but the thickness (D ₁ + D ₂ ) of the surface layer 7 is more than 5% of the total thickness (T) of the prepreg 1. If it is small, the air detachability is poor, and there is a possibility that the air cannot be sufficiently released. Conversely, the thickness (D ₁ + D ₂ ) of the surface layer 7 is more than 30% of the total thickness (T) of the prepreg 1. If it is large, the surface smoothness of the finally obtained printed wiring board and the circuit filling property of the resin 3 of the prepreg 1 may be adversely affected. On the other hand, if the height difference (D ₁ and D ₂ ) in the depth direction between the concave portion 5 and the convex portion 6 is smaller than 5 μm, there is a possibility that the air is not easily released and the air cannot be sufficiently released. When the height difference (D ₁ and D ₂ ) in the depth direction between the concave portion 5 and the convex portion 6 is larger than 40 μm, the surface smoothness of the finally obtained printed wiring board and the circuit filling of the resin 3 of the prepreg 1 May adversely affect sex. Incidentally, the height difference between the depth of the recess 5 and the convex portion 6 (D ₁ and D _2), by observing a cross section of the prepreg 1 with a microscope, can be confirmed.

  Moreover, it is preferable that the space | interval (W) between the adjacent convex parts 6 and 6 is 30-600 micrometers. It is technically difficult to form the unevenness 4 so that the interval (W) between the adjacent convex portions 6 and 6 is smaller than 30 μm, and conversely, the interval (W between the adjacent convex portions 6 and 6 ) Is larger than 600 μm, the surface smoothness of the finally obtained printed wiring board may be adversely affected. In addition, the space | interval (W) between the adjacent convex parts 6 and 6 can be confirmed by observing the surface of the prepreg 1 with a microscope.

  And the multilayer printed wiring board based on this invention can be manufactured as shown in FIG. 4 using the prepreg 1 obtained as mentioned above. In FIG. 4, reference numeral 11 denotes an inner layer substrate. The inner layer substrate 11 is not particularly limited as long as it has at least one of the through hole 9 and the non-through hole 10. Although not shown, the inner layer substrate 11 itself uses, for example, a commercially available double-sided copper-clad laminate as a core material, and laminates and forms a copper foil on both sides of the core material via a commercially available prepreg, This can be obtained by forming the through hole 9 and the non-through hole 10 by drilling / laser processing and then forming the circuit 15 on the outer copper foil. In this case, the inner layer substrate 11 is a four-layer plate. Each of the through hole 9 and the non-through hole 10 is a through via hole / non-through via hole for establishing conduction between different layers, but the inner layer substrate 11 shown in FIG. The circuit of the inner layer is not shown. Moreover, although the diameter of the through-hole 9 and the non-through-hole 10 is not specifically limited, For example, it is 50-600 micrometers.

  First, as shown to Fig.4 (a), metal foils 16, such as copper foil, are arrange | positioned through the prepreg 1 which concerns on this invention on both sides of the inner layer board | substrate 11. As shown in FIG. At this time, the surface where the unevenness 4 of the prepreg 1 according to the present invention is formed and the surface where the through hole 9 and the non-through hole 10 of the inner layer substrate 11 are opened are made to face each other.

Next, as shown in FIG.4 (b), it heat-presses on the conditions of 150-220 degreeC, 2.94-4.90 MPa (30-50 kg / cm < ² >), 30-120 minutes, and laminate-molding. The pressing direction is indicated by a white arrow. Since the pressurization is performed by applying a pressure of 2.94 MPa (30 kg / cm ² ) or more, the unevenness 4 formed on the prepreg 1 is crushed, but the degree of cure of the surface layer 7 is higher than that of the inner layer 8 of the prepreg 1. Since it is advanced, the unevenness 4 formed on the prepreg 1 is not immediately crushed but gradually crushed, and until it is completely crushed, through the gaps between the unevenness 4 and the outside, through holes 9 and non-through holes 10 can be kept in communication with the inside. That is, until the lamination molding is completed, the unevenness 4 formed in the prepreg 1 can secure an air escape path for escaping the air inside the through hole 9 and the non-through hole 10 to the outside. . This air flow is indicated by solid arrows in FIG. Thus, as the air inside the through hole 9 and the non-through hole 10 sews the gap by the irregularities 4 and escapes to the outside, the resin 3 of the prepreg 1 is filled inside the through hole 9 and the non-through hole 10. It will be done. In particular, the thickness (D) of the portion 7 where the irregularities 4 are formed, the height difference (D) in the depth direction between the concave portions 5 and the convex portions 6, and the interval (W) between the adjacent convex portions 6 and 6 are described above. When the prepreg 1 set to the predetermined value is used, the filling property of the resin 3 into the through hole 9 and the non-through hole 10 can be obtained high. In the case where the unevenness 4 is not formed at all on the surface of the prepreg 1, the entire surface of the prepreg 1 is the surface of the inner substrate 11 before all the air inside the through holes 9 and the non-through holes 10 escapes to the outside. Since it adheres to the whole, it is impossible to secure an air escape path and to prevent the generation of voids.

  When the lamination molding is completed, as shown in FIG. 4 (c), a multilayer laminated board 17 having no voids can be obtained, and then a circuit is formed on the outer metal foil 16 by a subtractive method or the like. A multilayer printed wiring board free from voids can be easily produced. Moreover, in the prepreg 1 according to the present invention, the curing time at 170 ° C. of the resin 3 of the surface layer 7 is shorter by 5 to 50 seconds than the curing time of the resin 3 of the inner layer 8. The outflow of the resin 3 is prevented, the moldability such as the circuit filling property can be obtained, and the productivity of the multilayer printed wiring board can be improved. If the difference between the curing time of the resin 3 of the surface layer 7 of the prepreg 1 and the curing time of the resin 3 of the inner layer 8 is shorter than 5 seconds, the outflow of the resin 3 at the time of laminate molding cannot be prevented, and the multilayer printed wiring On the contrary, if the difference between the curing time of the resin 3 of the surface layer 7 of the prepreg 1 and the curing time of the resin 3 of the inner layer 8 is longer than 50 seconds, unevenness will occur during lamination molding. 4 cannot be crushed completely, and voids remain.

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

<Pre-preg before forming irregularities>
As the substrate 2, two types of glass cloth “WEA1078” and “WEA7628” manufactured by Nitto Boseki Co., Ltd. were used.

  As the resin 3, the following FR-4 resin was used. That is, “Epicoat 828” (100 parts by mass) manufactured by Japan Epoxy Resin Co., Ltd. as a main agent, dicyandiamide (5.5 parts by mass) as a curing agent, and “2E4MZ” as a curing accelerator, “2E4MZ” ( 0.04 parts by mass) was dissolved in methyl ethyl ketone (MEK) to obtain the above FR-4 resin.

  Then, “WEA1078” was impregnated with FR-4 resin and dried at 160 ° C. for 6 minutes to obtain a prepreg 12 having an actual thickness of 75 μm before the formation of irregularities. Further, “WEA7628” was impregnated with FR-4 resin and dried at 160 ° C. for 6 minutes to obtain a prepreg 12 having an actual thickness of 200 μm before the formation of irregularities.

<Inner layer substrate>
An FR-4 grade double-sided copper-clad laminate “R-1766” manufactured by Matsushita Electric Works, Ltd. (copper foil thickness 18 μm, overall laminate thickness 0.2 mm) is used as a core material on both sides of the core material. A copper foil (thickness 18 μm) is placed and laminated through a commercially available prepreg “R-1661EG” (nominal thickness 60 μm) manufactured by Matsushita Electric Works, Ltd., and through holes 9 (diameter are formed by drilling / laser processing. 0.5 mm) and 300 non-through holes 10 (diameter 0.08 mm) are formed, and then a circuit 15 is formed on the outer copper foil, whereby an inner substrate 11 (four layers) as shown in FIG. Plate).

<Examples 1-9>
The metal plate 14 (iron plate) having the unevenness 13 formed on the surface is preheated to 150 ° C., and the unevenness forming surface of the metal plate 14 is opposed to the surface of the prepreg 12 before forming the unevenness, as shown in FIG. Both were arranged.

Next, as shown in FIG.1 (b), the prepreg 12 before unevenness formation and the metal plate 14 were press-contacted by the pressure of 0.0981 MPa (1 kg / cm < ² >). In addition, the uneven | corrugated formation surface of the metal plate 14 was processed with the mold release agent beforehand.

After 3 seconds have passed since the press-contact between the prepreg 12 and the metal plate 14 before forming the unevenness, the metal plate 14 is peeled off as shown in FIG. Obtained. Concavities and convexities 4 are formed on one side of the prepreg 1 thus obtained, and any concavities and convexities 4 exert a pressure of less than 2.94 MPa (30 kg / cm ² ) on the surface of the prepreg 1 at a temperature of 150 ° C. or less. It was confirmed that it has a strength that does not collapse even when it is applied. The curing time at 170 ° C. of the resin 3 of the surface layer 7, the curing time at 170 ° C. of the resin 3 of the inner layer 8, the height difference in the depth direction between the concave portion 5 and the convex portion 6, and the spacing between the adjacent convex portions 6 and 6. It is shown in the following [Table 1]. The curing time of the resin 3 of the surface layer 7 at 170 ° C. and the curing time of the resin 3 of the inner layer 8 at 170 ° C. are obtained by scraping and recovering the resin 3 of the surface layer 7 and the resin 3 of the inner layer 8 respectively. It was measured by carrying out a test method based on 6521.

  And as shown to Fig.4 (a), the metal foil 16 (18-micrometer-thick copper foil) was arrange | positioned through the prepreg 1 of Examples 1-9 on the both sides of the inner layer board | substrate 11. FIG.

Next, as shown in FIG.4 (b), it heat-pressed on 170 degreeC, 2.94 MPa (30 kg / cm < ² >), and the conditions for 60 minutes, and laminate-molded.

  When the lamination molding was completed, a multilayer laminated board 17 as shown in FIG. 4C was obtained.

<Comparative example>
In the process shown in FIG. 1, a multilayer laminate 17 was obtained in the same manner as in Examples 1 to 9 except that an iron plate having a flat surface was used instead of the metal plate 14 having the unevenness 13 formed on the surface. .

<Evaluation method>
By observing the cross section of the multilayer laminate 17 using a metal microscope, the filling property of the resin 3 in the through holes 9 and the non-through holes 10 was confirmed. The ratio of the through holes 9 in which the resin 3 is completely filled with respect to the 300 through holes 9 is shown in the column of “0.5 mm through hole” in [Table 1] below. The ratio of the non-through holes 10 completely filled with the resin 3 is shown in the column of “0.08 mm non-through holes” in [Table 1] below. Moreover, the presence or absence of a void was confirmed by observing the surface of the multilayer laminated board 17 using a metal microscope. The results are shown in the column “Presence / absence of voids after molding” in [Table 1] below.

  Since there are no voids in the multilayer laminates 17 of Examples 1 to 9, all of the prepregs 1 used to produce these multilayer laminates 17 are excellent in moldability such as circuit filling properties. It is confirmed.

An example of the manufacturing process of the prepreg which concerns on this invention is shown, (a)-(c) is sectional drawing. The other example of the manufacturing process of the prepreg which concerns on this invention is shown, (a)-(c) is sectional drawing. BRIEF DESCRIPTION OF THE DRAWINGS The prepreg which concerns on this invention is shown, (a) is sectional drawing of the prepreg in which the unevenness | corrugation was formed in one side, (b) is sectional drawing of the prepreg in which the unevenness | corrugation was formed in both surfaces. An example of the manufacturing process of the multilayer printed wiring board which concerns on this invention is shown, (a)-(c) is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Prepreg 2 Base material 3 Resin 4 Concavity and convexity 5 Concave part 6 Convex part 7 The part (surface layer) in which the unevenness | corrugation is formed
8 Other parts (inner layer)
9 Through-hole 10 Non-through-hole 11 Inner layer substrate

Claims (5)

  In the prepreg formed by impregnating the base material with resin and drying it, unevenness is formed on one or both sides of the prepreg, and the curing time at 170 ° C. of the resin in the portion where the unevenness is formed A prepreg characterized by being 5 to 50 seconds shorter than the curing time of the resin in the portion.   The thickness of the portion where the unevenness is formed is 5 to 30% of the thickness of the entire prepreg, and the height difference in the depth direction between the concave portion and the convex portion is 5 to 40 µm. The prepreg as described.   The prepreg according to claim 1 or 2, wherein an interval between adjacent convex portions is 30 to 600 µm. The prepreg according to any one of claims 1 to 3, wherein the unevenness does not collapse even when a pressure of less than 2.94 MPa (30 kg / cm ² ) is applied to the surface of the prepreg at a temperature of 150 ° C or lower. 5. The prepreg and the inner layer substrate, wherein the surface on which the unevenness of the prepreg according to claim 1 is formed is opposed to the surface of the inner layer substrate having at least one of a through hole and a non-through hole. A multilayer printed wiring board characterized by being formed by laminating.

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