JP2009141297A - Multilayer wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer wiring board which has high connection reliability, is optimum for making copper wiring layers small, and has interlayer connection portions excellent in productivity; and to provide its manufacturing method. <P>SOLUTION: The multilayer wiring board 1 comprises an insulating layer 2, a copper wiring upper layer 3 and a copper wiring lower layer 4 laminated on both sides of the insulating layer 2, a through-hole 5 penetrating the insulating layer 2 and at least the one copper wiring layer, and a solder conductor 6 filled in the through-hole 5 and connecting and making conductive the copper wiring upper layer 3 and the copper wiring lower layer 4. The solder-exposing surfaces exposed to the outmost surfaces with a part of the solder conductor 6 contacting with the copper wiring upper layer 3 and the copper wiring lower layer 4, and surfaces of the copper wiring upper layer 3 and the copper wiring lower layer 4 are integrally covered and connected with a plating film 8 composed of a metal. The plating film 8 composed of the metal is composed of a metal having a larger ionization tendency than the solder conductor 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wiring board on which various surface-mount type electronic components are mounted, and particularly to a multilayer wiring board having high connection reliability and a method for manufacturing the same.

  In recent years, with the reduction in size and weight and higher functionality of electronic devices, the wiring density of wiring boards used tends to further increase. As means for increasing the wiring density of this wiring board, there is a limit only by miniaturization of the copper wiring layer. Therefore, a multilayer wiring board in which copper wiring layers are stacked, an interlayer connection portion is provided in an insulating layer between copper wiring layers, the copper wiring layers are three-dimensionally connected, and the wiring density is further increased is drawing attention.

  Conventionally, multilayer wiring boards have different characteristics depending on the difference in the insulating layers used. For example, when the most popular glass cloth impregnated epoxy resin base material (hereinafter abbreviated as a glass epoxy base material) is used as the insulating layer, the cost can be reduced, and an electrically insulating film represented by polyimide can be used. When used, it is possible to reduce the thickness and weight. Although it is a multilayer wiring board having various characteristics due to the difference in the insulating layer, basically the same technique is used for the interlayer connection method. This interlayer connection method will be described below by taking a multilayer wiring board using a polyimide film as an example.

  In the method, a through-hole which is a through-hole is provided in a copper-clad double-sided substrate in which copper foil is laminated on both sides of an insulating layer made of polyimide film, and a copper plating film is formed on the wall surface of the through-hole. A copper foil is three-dimensionally interconnected (for example, refer to Patent Document 1).

  This interlayer connection method is called a plated through hole method and is the most common interlayer connection method. This manufacturing method is composed of two major steps: a step of converting the wall surface of the through-hole that is insulative into a conductor by electroless plating and a step of performing thick plating of copper by electrolytic plating. As a feature, since the thermal expansion coefficient of the copper plating film in the through hole and the insulating layer made of the polyimide film is substantially the same, the connection reliability against heat is excellent.

  However, when copper thick plating is applied, not only the thickness of the copper plating film in the through hole, but also the thickness of the copper foil formed on both surfaces of the insulating layer is increased, and the copper wiring layer by the subsequent etching process It becomes difficult to miniaturize. In addition, the process is lengthy, and productivity remains a problem.

  As a method of interlayer connection to solve these problems, a method of printing a solder paste in a through hole and melting and solidifying it (for example, see Patent Document 2) has been proposed. As a feature of this method, since it can be manufactured by a simple process compared to the plated through hole method described above, the productivity is high, and since the interlayer connection is performed after the formation of the copper wiring layer, there is no influence on the thickness of the copper foil in the process. Does not hinder the miniaturization of the copper wiring layer.

  However, the thermal expansion coefficient of the solder is larger than that of the insulating layer made of polyimide film, and when heated, the solder in the through hole expands more than the insulating layer, and the bonding interface between the copper wiring layer and the solder on the surface of the insulating layer peels off. There is a risk. As described above, the method using solder has a problem that connection reliability by heat is not sufficient.

The above problems are common to the multilayer wiring boards of glass epoxy base materials obtained by the same interlayer connection method.
JP-A-5-175636 JP-A-7-176847

  As described above, the interlayer connection of the multilayer wiring board by the conventional plated through-hole method is excellent in connection reliability, but there are problems in miniaturization of the copper wiring layer and improvement in productivity, and a method using solder However, there is a problem in connection reliability, although the above-described problem can be achieved by miniaturization of the copper wiring layer and improvement of productivity.

  Therefore, in interlayer connection of multilayer wiring boards, a multilayer wiring board having high productivity capable of achieving both high connection reliability and miniaturization of a copper wiring layer has been required.

  In view of the above problems, an object of the present invention is to provide a multilayer wiring board having an interlayer connection portion having high connection reliability, optimum for miniaturization of a copper wiring layer, and excellent in productivity, and a manufacturing method thereof. .

  In order to solve the above problems, a multilayer wiring board according to the present invention includes an insulating layer, a copper wiring layer laminated on both surfaces of the insulating layer, and a through-hole penetrating the insulating layer and at least one of the copper wiring layers. And a multilayer wiring board comprising a solder conductor filled in the through-hole and connected and conductive between the copper wiring layers, wherein a part of the solder conductor is in contact with the copper wiring layer and exposed to the outermost surface. The exposed surface of the solder and the surface of the copper wiring layer are coated and integrated with a metal plating film, and the metal plating film is made of a metal having a higher ionization tendency than the solder conductor. It is a thing.

  In addition, in order to solve the above problems, the method of manufacturing a multilayer wiring board according to the present invention includes the copper wiring layer and the insulating layer at a predetermined interlayer connection position of a double-sided wiring board in which a copper wiring layer is formed on both surfaces of the insulating layer. A solder conductor is formed by press-fitting a substantially spherical solder ball, and a part of the solder conductor is in contact with the copper wiring layer and exposed to the outermost surface. The solder exposed surface and the surface of the copper wiring layer are electroplated with a nickel plating film to conduct electricity between the copper wiring layers.

  Here, since this metal plating film is electrodeposition on the metal surfaces having different ionization tendencies, that is, solder and copper, a local battery is formed between the solder and copper as soon as it is immersed in a normal acidic plating solution. Using the electromotive force of the battery as a driving force, solder having a higher ionization tendency is ionized and dissolved in the liquid, and the corrosion of the solder proceeds. It is very difficult to form a metal plating film on the corroding solder surface. The solder here is tin or a tin alloy containing tin as a main component.

  Therefore, the present inventors have conducted intensive research on electrodeposition on metal surfaces having different ionization tendencies, and can be realized by selecting a metal plating film having a greater ionization tendency than solder as the metal plating film. I came to find. In other words, in order to suppress this solder corrosion, electrodeposition is performed in a plating solution in which a metal whose ionization tendency is larger than that of the solder is dissolved, so that the metal plating film is formed on the surface while preventing corrosion due to ionization of the solder. As a result, only the metal plating film having a higher ionization tendency than the solder conductor can be integrated and joined.

  As a result, an integrated structure in which the surface of the solder conductor used for the interlayer connection and the copper wiring layer is covered with the metal plating film can be realized, and the metal plating film regulates the solder conductor that expands when heated, and the thermal stress Therefore, the bonding between the solder conductor and the copper wiring layer can be sufficiently secured, and high connection reliability can be obtained.

  In addition, this metal plating film is not the role of electrical wiring as in the conventional plating through-hole method, but is mainly intended to regulate thermally expanded solder conductors. The film thickness can be reduced. Therefore, in the manufacturing method, a nickel plating film, which is a thin metal plating film, is formed for interlayer connection after the copper wiring layer is formed, so that the influence on the copper wiring layer is small and suitable for miniaturization of the copper wiring layer. . Furthermore, since the interlayer connection is performed by a very simple process of filling the solder conductor and metal plating, high productivity can be secured.

  According to the multilayer wiring board according to claim 1 of the present invention, the exposed solder surface and the copper wiring layer surface in which a part of the filled solder conductor is in contact with the copper wiring layer and exposed on the outermost surface, Since the interlayer connection part has an integrated structure coated with a metal plating film that has a higher ionization tendency than solder, it is possible to cover the solder and copper surfaces by selecting a metal plating film that has a higher ionization tendency than solder. The metal plating film has an effect of suppressing the stress of the solder conductor thermally expanded and obtaining a multilayer wiring board having high connection reliability.

  According to the multilayer wiring board according to claim 2 of the present invention, since copper having good thermal expansion coefficient matching with the insulating layer is included in the core portion of the solder conductor, the thermal expansion coefficient of the entire solder conductor is reduced. There is an effect that a multilayer wiring board which is effectively optimized and has high connection reliability can be obtained.

  According to the multilayer wiring board according to claim 3 of the present invention, since the ionization tendency is larger than that of the solder and a relatively hard nickel or nickel alloy is used as the metal plating film, the metal plating is applied to the solder and the copper surface. The film can be covered, and the stress of the solder conductor in which the metal plating film is thermally expanded can be surely suppressed, so that there is an effect that a multilayer wiring board having higher connection reliability can be obtained.

  According to the multilayer wiring board of the present invention, the dissimilar metal plating film is formed on the surface of the metal plating film that covers and protects the surface of the solder conductor and the surface of the copper wiring layer. Because it can be selected from ordinary plating metal without being restricted by ionization tendency and the surface plating coating can be selected according to the product, it is possible to obtain a multilayer wiring board with a high degree of freedom in product design. is there.

  According to the multilayer wiring board of claim 5 of the present invention, since the metal plating film is partially plated only in the region including the interlayer connection portion, the metal plating film is not formed on the surface of the other copper wiring layer, Since there is no influence on the copper wiring layer in the process, there is an effect that a multilayer wiring board with high connection reliability excellent in miniaturization of the copper wiring layer can be obtained.

  According to the method for manufacturing a multilayer wiring board according to claim 6 of the present invention, since the nickel plating film is formed thinly for interlayer connection after the copper wiring layer is formed, there is little influence on the copper wiring layer, and the copper wiring layer It is suitable for miniaturization of solder, and since the interlayer connection is performed by a very simple process of filling the solder conductor and metal plating, it is possible to manufacture a multilayer wiring board with a fine wiring layer with high productivity. There is.

  According to the method for manufacturing a multilayer wiring board according to claim 7 of the present invention, since a single-sided wiring board having a very fine copper wiring layer is used as a process material, a multilayer wiring board having a further fine copper wiring layer is provided. There is an effect that it can be manufactured.

  According to the method for manufacturing a multilayer wiring board according to claim 8 of the present invention, since the blind via hole is used for interlayer connection, there is an effect that a multilayer wiring board having higher connection reliability can be manufactured.

  According to the method for manufacturing a multilayer wiring board according to claim 9 of the present invention, by using a copper core solder ball instead of a solder ball that fills through holes and blind via holes and serves as a solder conductor for interlayer connection, Multi-layer wiring with high connection reliability because the thermal expansion coefficient of the entire solder conductor is effectively optimized because copper with good thermal expansion coefficient matching with the insulating layer is included in the core of the solder conductor. There is an effect that a plate is obtained.

  The multilayer wiring board according to claim 1 of the present invention includes an insulating layer, a copper wiring layer laminated on both surfaces of the insulating layer, a through-hole penetrating the insulating layer and at least one of the copper wiring layers. A multilayer wiring board comprising a solder conductor filled in the through-hole and connecting and conducting between the copper wiring layers, wherein a part of the solder conductor is in contact with the copper wiring layer and exposed on the outermost surface. The exposed solder surface and the copper wiring layer surface are coated and integrated with a metal plating film, and the metal plating film is made of a metal having a higher ionization tendency than the solder conductor. Is. With this configuration, since a metal having a higher ionization tendency than solder is used as the metal plating film, the metal plating film can be coated on the solder and the copper surface, and the stress of the solder conductor in which the metal plating film is thermally expanded can be suppressed. It has the action.

  The multilayer wiring board according to claim 2 of the present invention is the multilayer wiring board according to claim 1, wherein the solder conductor has a copper piece smaller than the diameter of the through hole in the core portion, and the surface is a solder metal layer. It is provided with being covered. With this configuration, copper having good thermal expansion coefficient matching with the insulating layer is included in the core portion of the solder conductor, so that the thermal expansion coefficient of the entire solder conductor can be optimized and heat generated by the difference in thermal expansion can be achieved. It has the effect that stress can be relaxed.

  A multilayer wiring board according to a third aspect of the present invention is the multilayer wiring board according to the first and second aspects, wherein the metal plating film includes at least one of nickel and a nickel alloy. This configuration has a higher ionization tendency than solder and uses relatively hard nickel or nickel alloy among the metal materials as the metal plating film, so the metal plating film can be coated on the solder and copper surfaces, and the metal plating film is thermally expanded. It has the effect | action that the stress of the solder conductor which carried out can be suppressed reliably.

  A multilayer wiring board according to a fourth aspect of the present invention is the multilayer wiring board according to the first to third aspects, further comprising laminating at least one kind of different metal plating film on the surface of the metal plating film. is there. With this configuration, the dissimilar metal plating film is formed on the surface of the metal plating film that covers and protects the surface of the solder conductor and the copper wiring layer, so that the metal plating film serves as a barrier layer and is restricted by ionization tendency. And has the effect of being able to select from ordinary plated metals.

  A multilayer wiring board according to a fifth aspect of the present invention is the multilayer wiring board according to the first to fourth aspects, wherein the metal plating film is partially plated only in a region including at least a range filled with a solder conductor. It is equipped with. With this configuration, since the metal plating film is covered only in the region including the interlayer connection portion, the metal plating is not formed on the surface of the other copper wiring layer.

  According to a sixth aspect of the present invention, there is provided a method for manufacturing a multilayer wiring board, wherein the copper wiring layer and the insulating layer are penetrated at a predetermined interlayer connection position of a double-sided wiring board in which a copper wiring layer is formed on both surfaces of the insulating layer. After forming the through-hole, a solder conductor is formed by press-fitting a substantially spherical solder ball, and a part of the solder conductor is in contact with the copper wiring layer and exposed on the outermost surface. Conduction between the copper wiring layers is provided by electrodepositing a nickel plating film on the exposed solder surface and the copper wiring layer surface by electrolytic nickel plating. With this configuration, a thin copper plating film is formed after the copper wiring layer is formed, so that the effect on the copper wiring layer is small, and the process of interlayer connection such as filling of the solder conductor and metal plating can be greatly simplified. It has the action.

  A method for manufacturing a multilayer wiring board according to claim 7 of the present invention is the method for manufacturing a multilayer wiring board according to claim 6, wherein two single-sided wiring boards having a copper wiring layer formed on one side of an insulating layer are provided. The double-sided wiring board is formed by bonding the copper wiring layer through an adhesive layer in the direction in which the copper wiring layer becomes the outermost layer. With this configuration, a single-sided wiring board can be made finer than a double-sided wiring board, and a double-sided wiring board is obtained by laminating this single-sided wiring board. It has the effect | action that a board is obtained.

  The method for manufacturing a multilayer wiring board according to claim 8 of the present invention is such that the copper wiring layer and the insulating layer are penetrated at a predetermined interlayer connection position of the single-sided wiring board in which the copper wiring layer is formed on one side of the insulating layer. Forming a through-hole, and laminating via a bonding layer on the copper wiring layer surface of another single-sided wiring board in a direction in which the copper wiring layer of the single-sided wiring board becomes the outermost layer, A solder exposed surface is formed by press-fitting a substantially spherical solder ball into a blind via hole to form a solder conductor, and a part of the solder conductor is in contact with the copper wiring layer and exposed on the outermost surface. And the copper wiring layer surface are electroplated by electrolytic nickel plating to provide electrical conduction between the copper wiring layers. With this configuration, a solder ball is press-fitted into a blind via hole that is non-penetrating and has a wiring layer on the bottom surface to deform the metal layer on the surface and take interlayer conduction. The bonding area with the copper wiring layer increases and the adhesion strength between the two increases.

  A method for producing a multilayer wiring board according to claim 9 of the present invention is the method for producing a multilayer wiring board according to claims 6 to 8, wherein the solder ball has a copper piece smaller than the diameter of the through hole in the core portion. And the surface is covered with a solder metal layer. With this configuration, copper having good thermal expansion coefficient matching with the insulating layer is included in the core portion of the solder conductor, so that the thermal expansion coefficient of the entire solder conductor can be optimized and heat generated by the difference in thermal expansion can be achieved. It has the effect that stress can be relaxed.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted. The numerical values shown in the embodiments are examples that can be selected in various ways, and are not limited thereto.

(Embodiment)
A multilayer wiring board according to an embodiment of the present invention will be described below. First, the multilayer wiring board of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a main part of a multilayer wiring board according to an embodiment of the present invention. In the embodiment of the present invention, a multilayer wiring board using an electrically insulating film is mainly described. However, since the multilayer wiring board of a glass-epoxy base material is basically the same, the multilayer wiring board is basically the same here. Detailed description is omitted.

  In FIG. 1, reference numeral 1 denotes a multilayer wiring board in which a copper wiring upper layer 3 and a copper wiring lower layer 4 are formed on both sides of an insulating layer 2 made of a polyimide film, and each copper conductor is filled with a solder conductor 6 filled in a through hole 5. Interlayer connection of wiring layers is performed. Here, the solder conductor 6 is formed by pressurizing and deforming solder balls 7 in the thickness direction of the insulating layer 2. Further, the surface of the filled solder conductor 6 and the surface of each copper wiring layer are covered with a plating film 8.

  As shown in FIG. 1, the solder conductor 6 that performs interlayer connection of the multilayer wiring board 1 can be formed in a state in which the solder ball 7 is in close contact with the through hole 5 by press-fitting and deforming the solder ball 7. It is joined to the copper wiring upper layer 3 and the copper wiring lower layer 4. Further, the surface of the solder conductor 6 and the surface of each copper wiring layer are covered and integrated with a plating film 8, and the plating film 8 regulates the solder conductor 6 that expands when heated, thereby suppressing thermal stress. It has become.

  Here, the plating film 8 is made of a metal having a higher ionization tendency than solder. This is the reason for using a metal having a higher ionization tendency than solder, but since the present invention is electrodeposition on the metal surface with different ionization tendency of solder and copper, the solder and copper are immediately immersed in an ordinary acidic plating solution. A local battery is formed between the solder and the solder having a larger ionization tendency, and the corrosion of the solder proceeds. In order to suppress this solder corrosion, a plating film is formed on the surface while preventing corrosion due to ionization of the solder by performing electrodeposition in a plating solution in which a metal whose ionization tendency is larger than that of the solder is dissolved. As a result, it is possible to cover only with a plating film having a higher ionization tendency than the solder conductor. The solder here is tin or a tin alloy containing tin as a main component, that is, it can be coated only with a metal plating film having a higher ionization tendency than tin.

  As a result, when a conductor composed only of solder was heated, which was the biggest problem of using solder for interlayer connection, the solder in the through hole expanded beyond the insulating layer, and the copper wiring layer on the surface of the insulating layer and the solder This solves the problem that the bonding interface with the surface is peeled off and the connection reliability by heat cannot be ensured. Therefore, high reliability of connection can be obtained by this structure.

  The solder conductor 6 may be filled with a copper core solder ball having a copper piece smaller than the through-hole 5 in the core portion and having the surface covered with a solder metal layer. This is because copper having good thermal expansion coefficient matching with the insulating layer 2 is included in the core portion of the solder conductor 6, so that the thermal expansion coefficient of the entire solder conductor 6 can be optimized and The generated thermal stress can be relaxed, and higher connection reliability can be obtained. Either may be used as appropriate. Further, the solder composition of the solder conductor 6 may be any suitable one such as eutectic solder, high temperature solder, lead-free solder and the like.

  Insulating layer 2 includes an electrically insulating film such as polyimide film, PET (polyethylene terephthalate) film, PEN (polyethylene naphthalate) film, polyester film, polyamideimide film, PEI (polyetherimide) film, PEEK (polyethylene). Ether ether ketone) film, PES (polyethersulfone) film, PPS (polyphenylene sulfide) film, aramid film, LCP film, PTFE (polytetrafluoroethylene) film, etc. can be used. May be. Among these, it is most preferable to use a polyimide film excellent in heat resistance, dimensional stability, and mechanical properties. Furthermore, when a glass epoxy substrate is used as the insulating layer 2, a resin material including a phenol resin, a melamine resin, a polyester resin, a diethyl phthalate resin, an epoxy resin, and a modified resin thereof can be used as the thermosetting resin. Paper, cloth, glass cloth, and non-woven fabric (synthetic, natural, inorganic, and organic fibers may be used) can be used in the thermosetting resin, and any of these may be used as appropriate. .

  Further, examples of the plating film 8 having a higher ionization tendency than solder include nickel, nickel alloy, zinc, and zinc-based alloy, but it is most preferable to use at least one of nickel or nickel alloy. This is because a relatively hard nickel or nickel alloy among the metal materials is used as the plating film 8, so that the stress of the solder conductor 6 in which the metal plating film is thermally expanded can be reliably suppressed, and higher connection reliability can be obtained.

  Further, a dissimilar metal plating film may be formed on the surface of the plating film 8. Since this dissimilar metal plating film is formed on the surface of the plating film 8 that covers and protects the surface of the solder conductor 6 and the surface of each copper wiring layer, the plating film 8 serves as a barrier layer and restricts the ionization tendency. Without receiving, it can be selected from ordinary plating metal. Therefore, the plating coating on the surface can be selected according to the product, and the design flexibility of the product can be increased. Here, examples of the dissimilar metal plating film include gold, silver, palladium, tin, copper, and alloys thereof, and any of them may be used as appropriate.

  Alternatively, the plating film 8 may be partially plated only in a region including the interlayer connection portion. The coating of the plating film 8 that limits this range has no effect on the copper wiring layer in the process because the plating film 8 is not formed on the surface of the other copper wiring layer, and is a structure suitable for miniaturization of the copper wiring layer. It becomes. Therefore, it is possible to obtain a multilayer wiring board having high connection reliability and excellent in miniaturization of the copper wiring layer.

  Next, a method of manufacturing such a multilayer wiring board having high connection reliability will be described in more detail with reference to FIGS. 2 to 4 using copper core solder balls. The same reference numerals as those in FIG. 1 are basically the same in FIG. 2 to FIG.

  Initially, the manufacturing method of the multilayer wiring board in one embodiment of this invention is demonstrated using FIG. 2A is a cross-sectional view of the main part of a double-sided copper-clad laminate that is a raw material in one embodiment of the present invention, and FIG. 2B is a double-sided surface on which a copper wiring layer is formed in one embodiment of the present invention. Fig. 2 (c) is a cross-sectional view of the main part of the wiring board, Fig. 2 (c) is a cross-sectional view of the main part of the double-sided wiring board in which the through hole is formed in the embodiment of the present invention, and Fig. FIG. 2E is a cross-sectional view of the main part of the double-sided wiring board after the copper core solder ball is press-fitted and deformed in one embodiment of the present invention. FIG. 2 (f) is a cross-sectional view of the main part of the double-sided wiring board on which a plating film is formed in one embodiment of the present invention, and FIG. 2 (g) is a multilayer wiring board after interlayer connection in one embodiment of the present invention. FIG.

  In FIG. 2, 9 is a double-sided copper-clad laminate in which copper foils 10 are directly formed on both sides of the insulating layer 2, and 11 is a double-sided wiring board in which the double-sided copper-clad laminate 9 is etched to form a copper wiring layer. is there. Reference numeral 12 denotes a punching die for processing through holes. Reference numeral 13 denotes a copper core solder ball having a copper piece 14 in the core portion. Reference numerals 15 and 16 denote an upper pressure plate and a lower pressure plate for press-fitting and deforming the copper core solder ball 13. Reference numeral 17 denotes a plating bath for forming the plating film 8, and 18 denotes a counter electrode for plating.

  First, as shown in FIG. 2A, a double-sided copper-clad laminate 9 in which copper foils 10 are directly formed on both sides of an insulating layer 2 is prepared. In addition, in one embodiment of the present invention, a two-layer type without an adhesive layer between the insulating layer 2 and the copper foil 10 is cited, but a three-layer type with an adhesive layer can also be used, Any one of them may be used as appropriate and is not limited thereto.

  Next, as shown in FIG. 2 (b), a mask material is formed on the surface of the copper foil 10, and an etching process is performed using an etching solution of copper such as iron chloride or copper chloride. A double-sided wiring board 11 on which the wiring lower layer 4 is formed is obtained.

  Further, as shown in FIG. 2C, the through hole 5 is formed by punching using a punching die 12. In the embodiment of the present invention, punching is used, but drilling, laser processing, and etching can be used depending on the type of insulating layer 2 and the size and accuracy of the through hole. Any one may be used as appropriate, and the present invention is not limited to this.

  Further, as shown in FIG. 2D, after the copper core solder ball 13 having the copper piece 14 at the core portion is arranged at the position of the through hole 5, the copper core solder ball 13 is pressed against the pressure upper plate 15 and the pressure lower plate. In the plate 16, press-fitting deformation into the through hole 5 is started. As a method for arranging the copper core solder balls 13, a conventionally known method of mounting solder balls on a semiconductor package called BGA can be used. Specifically, a suction plate having a suction hole smaller in diameter than the copper core solder ball 13 at a position corresponding to the through hole 5 is prepared and connected to a vacuum pump for adjusting the pressure in the suction hole. Using this suction plate, the copper core solder ball 13 is sucked into the suction hole, aligned with the upper portion of the through hole 5, the copper core solder ball 13 is dropped, and the copper core solder ball 13 is placed at the through hole position. It is also possible to use equipment called a ball mounter that performs the above operations. Here, an example of mounting the copper core solder ball 13 by vacuum suction is shown, but other methods such as electrostatic suction may be used.

  Next, as shown in FIG. 2 (e), the copper conductor solder ball 13 is press-fitted and deformed into the through hole 5 by the pressurizing upper plate 15 and the pressurizing lower plate 16, and the solder conductor 6 filled in the through hole 5. Is formed. Here, since the copper core solder balls 13 are made of a soft metal made of a solder alloy, the copper core solder balls 13 are sequentially deformed along with the press-fitting and deformed along the inner wall of the through-hole 5 so that there is no gap in the through-hole 5. The solder conductor 6 can be completely filled. By this solder conductor 6, the copper wiring upper layer 3 and the copper wiring lower layer 4 are electrically connected.

  Further, as shown in FIG. 2 (f), the double-sided wiring board 11 filled with the solder conductor 6 is immersed in a plating bath 17, energized using the counter electrode 18, and made of a metal having a high ionization tendency. A plated film 8 is formed on the surface of the exposed solder where a part of the solder conductor 6 is exposed on the outermost surface and the surface of each copper wiring layer, and as shown in FIG. Between the copper wiring layers is made conductive by the solder conductor 6 filled in, and the surface of the solder conductor 6 having the copper piece 14 in the core portion and the surface of each copper wiring layer are integrally covered with the plating film 8. A multilayer wiring board 1 having high connection reliability is obtained.

  Here, the plating film 8 is not used as an electric wiring as in the conventional plating through-hole method, but mainly for the regulation of the thermally expanded solder conductor 6, so that the plating film 8 is plated compared to the plating through-hole method. The film thickness can be reduced. Therefore, in the manufacturing method, since a thin plating film is formed for interlayer connection after the copper wiring layer is formed, there is little influence on the copper wiring layer and it is suitable for miniaturization of the copper wiring layer. Furthermore, before the plating film 8 is formed, masking that exposes the vicinity of the interlayer connection portion is performed, and a partial plating method in which the plating film 8 is not formed on the surface of another copper wiring layer can be used. According to this method, since the plating film 8 is not formed on the surface of another copper wiring layer, the manufacturing method is suitable for further miniaturization of the copper wiring layer.

  In the production method of this production method, a plurality of products are arranged on a hoop-shaped or sheet-shaped raw material, each process is performed, and the product outer shape can be cut out in the final process. Among these, the hoop treatment is the most desirable because it is a production form with good productivity.

  The method for manufacturing a multilayer wiring board in one embodiment of the present invention obtained as described above has the following characteristics. First, since the surface of the solder conductor for interlayer connection and the copper wiring layer are covered with a plating film and have an integral structure, the stress caused by the difference in thermal expansion can be suppressed and high connection reliability can be obtained. Furthermore, since a thin plating film for interlayer connection is formed after the copper wiring layer is formed, there is little influence on the copper wiring layer, which is suitable for miniaturization of the copper wiring layer. Finally, interlayer connection can be performed by a very simple process of solder ball filling and metal plating, and the number of processes is small compared to other interlayer connection methods, and the productivity is greatly improved. Therefore, according to the present invention, it is possible to obtain a multilayer wiring board having high connection reliability, optimal for miniaturization of a copper wiring layer, and having interlayer connection excellent in productivity.

  Next, a method for manufacturing a multilayer wiring board according to an embodiment of the present invention, which is further excellent in connection reliability and miniaturization of a copper wiring layer, will be described with reference to FIG. FIG. 3A is a cross-sectional view of an essential part of a single-sided copper-clad laminate with an adhesive layer, which is a raw material in one embodiment of the present invention, and FIG. 3B is formed by a copper wiring layer in one embodiment of the present invention. FIG. 3C is a cross-sectional view of the main part of the single-sided wiring board with an adhesive layer formed, FIG. 3C is a cross-sectional view of the main part of the single-sided wiring board with the adhesive layer in which the through hole is formed in one embodiment of the present invention ) Is a cross-sectional view of the main part of the multilayer wiring board in which the blind via hole in one embodiment of the present invention is formed, and FIG. 3 (e) is a diagram illustrating both surfaces of the copper core solder ball according to the embodiment of the present invention after the press-fitting deformation. Fig. 3 (f) is a cross-sectional view of the main part of the multilayer wiring board after the interlayer connection formed with the plating film according to the embodiment of the present invention.

  In FIG. 3, reference numeral 19 denotes a single-sided copper-clad laminate with an adhesive layer in which a copper foil 10 is formed on one side of the insulating layer 2 and an adhesive layer 20 is formed on the other side. Reference numeral 21 denotes a single-sided wiring board with an adhesive layer obtained by etching the single-sided copper-clad laminate 19 with an adhesive layer to form a copper wiring upper layer 3. Reference numeral 23 denotes another single-sided wiring board laminated with the single-sided wiring board 21 with an adhesive layer. Reference numeral 24 denotes a multilayer wiring board in which the single-sided wiring boards 21 and 23 with an adhesive layer are laminated and a blind via hole 22 is formed for interlayer connection. Reference numeral 25 denotes a multilayer wiring board having the solder conductor 6 filled in the blind via hole 22 and integrally covering the surface of the solder conductor 6 and the surface of the copper wiring upper layer 3 with a plating film 8.

  First, as shown in FIG. 3A, a single-sided copper-clad laminate 19 with an adhesive layer in which the copper foil 10 is directly formed on one side of the insulating layer 2 and the adhesive layer 20 is formed on the other side is prepared. As shown in FIG.3 (b), the copper wiring upper layer 3 is formed by an etching process, and the single-sided wiring board 21 with an adhesive layer is obtained. The copper wiring upper layer 3 of the single-sided wiring board 21 with an adhesive layer obtained here can be further miniaturized because it can be etched on one side suitable for miniaturization compared to the copper wiring layer of the double-sided wiring board. It has become.

  The reason is described below. Normally, when forming a copper wiring layer on a double-sided wiring board, the copper foil on both sides of the double-sided copper-clad laminate is etched simultaneously, so it is necessary to apply the etching solution uniformly from the top and bottom of the double-sided copper-clad laminate. is there. However, when the etching solution is sprayed under pressure from above and below the double-sided copper clad laminate, there is a problem that the etching solution after spraying on the upper surface accumulates on the upper surface and the etching uniformity cannot be maintained. Therefore, in the double-sided wiring board, the etching conditions become unstable, and it is difficult to form a very fine copper wiring layer. On the other hand, in forming a copper wiring layer of a single-sided wiring board, spraying from the lower side is sufficient, so that the etching liquid cannot be pooled. Therefore, the optimum range of etching conditions can be widened and suitable for miniaturization of the copper wiring layer. .

  Next, as shown in FIG. 3 (c), punching using a punching die 12 is performed on the single-sided wiring board 21 with an adhesive layer to form a through hole 5, and as shown in FIG. 3 (d), The single-sided wiring board 21 with the adhesive layer and the other single-sided wiring board 23 on which the copper wiring lower layer 4 is formed are bonded via the adhesive layer 20, and the multilayer wiring board 24 in which the blind via hole 22 for interlayer connection is formed. obtain. Since the multilayer wiring board 24 obtained here has a single-sided wiring board having a fine copper wiring layer, the copper wiring layer becomes finer than the wiring layer of the double-sided wiring board. In addition, although the multilayer wiring board 24 is mentioned as a lamination | stacking method of the single-sided wiring board in one embodiment of this invention, it puts two single-sided wiring boards through an adhesive layer in the direction where a copper wiring layer becomes an outermost layer. Even if the laminated double-sided wiring board is formed, the copper wiring layer can be miniaturized. Any of the lamination methods may be used as appropriate and is not limited thereto.

  Further, as shown in FIG. 3E, a solder conductor 6 is formed by press-fitting and deforming a copper core solder ball into the blind via hole 22. Since the solder conductor 6 obtained here is filled in the blind via hole 22 having the copper wiring lower layer 4 on the bottom surface, the bonding area between the solder conductor 6 and the copper wiring lower layer 4 is smaller than that of the through hole. The adhesion strength between the two increases. Therefore, even when various external stresses are applied, the connection interface between the copper wiring lower layer 4 and the solder conductor 6 does not peel off, and higher connection reliability can be obtained.

  Finally, as shown in FIG. 3 (f), a solder exposed surface in which a part of the solder conductor 6 is exposed on the outermost surface of the plating film 8 made of a metal having a large ionization tendency by electrodeposition of the plating bath. And the surface of the solder conductor 6 having the copper piece 14 in the core portion, and the copper conductor layer 6 are electrically connected to each other by the solder conductor 6 filled in the blind via hole 22. A multilayer wiring board 25 in which the surface of the wiring layer is integrally covered with the plating film 8 is obtained.

  The method for manufacturing a multilayer wiring board according to one embodiment of the present invention obtained as described above is for laminating a single-sided wiring board, so that the copper wiring layer is finer than a copper wiring layer of a double-sided wiring board. Become. Further, since the solder conductor is filled in the blind via hole by press-fitting and deforming the copper core solder ball, higher connection reliability can be obtained as compared with the through hole. Therefore, according to the present invention, it is possible to obtain a multilayer wiring board having high connection reliability, optimum for miniaturization of a copper wiring layer, and having interlayer connection excellent in productivity.

  Finally, a multilayer wiring board according to an embodiment of the present invention in which the above-described multilayer wiring board is further laminated will be described with reference to FIG. FIG. 4A is a cross-sectional view of the main part of the multilayer wiring board after lamination in one embodiment of the present invention, and FIG. 4B is the main part of another multilayer wiring board after lamination in one embodiment of the present invention. FIG.

  In FIG. 4, reference numeral 26 denotes a multilayer wiring board in which the multilayer wiring board 1 and the multilayer wiring board 25 are laminated via the adhesive layer 20. First, as shown in FIG. 4A, the multilayer wiring board 1 and the multilayer wiring board 25 manufactured according to the above-described embodiment of the present invention are further laminated via the adhesive layer 20, and the number of copper wiring layers is determined. An increased multilayer wiring board 26 is obtained. The multilayer wiring board 26 obtained here has high connection reliability because the multilayer wiring board 1 and the multilayer wiring board 25 which are constituent materials have high connection reliability and a fine copper wiring layer. Excellent in miniaturization.

  Also, as shown in FIG. 4B, the multilayer wiring board 27 is obtained by laminating the multilayer wiring board 1 and the plating film 8 of the multilayer wiring board 25 so as to be in contact with each other. Here, since the plating film 8 is a metal layer, each wiring layer can be electrically connected. Further, when a solder plating film is laminated on the surface of the plating film 8, when the solder plating films are brought into contact with each other and heated and cooled, the solder plating films are melted and solidified and easily joined together to improve connection reliability.

  The multilayer wiring board according to one embodiment of the present invention obtained as described above has high connection reliability and is formed by further laminating multilayer wiring boards having fine copper wiring layers. High and excellent in miniaturization of the copper wiring layer. Therefore, according to the present invention, it is possible to obtain a multilayer wiring board having high connection reliability, optimum for miniaturization of a copper wiring layer, and having interlayer connection excellent in productivity.

  According to the present invention, it is possible to provide a multilayer wiring board having high connection reliability, optimal for miniaturization of a copper wiring layer, and having an interlayer connection excellent in productivity, and a manufacturing method thereof.

Sectional drawing of the principal part of the multilayer wiring board in one embodiment of this invention (A) The principal part sectional drawing of the double-sided copper clad laminated board which is a raw material in one embodiment of this invention, (b) The principal part cross section of the double-sided wiring board in which the copper wiring layer in one embodiment of this invention was formed FIG. 3C is a cross-sectional view of a main part of a double-sided wiring board in which a through hole is formed in one embodiment of the present invention. FIG. 3D is a double-sided wiring board before a copper core solder ball is press-fitted in one embodiment of the present invention. (E) Cross-sectional view of the main part of the double-sided wiring board after the copper core solder ball in one embodiment of the present invention is press-fitted and deformed, (f) Plating film in one embodiment of the present invention is formed Cross-sectional view of the principal part of the double-sided wiring board inside, (g) Cross-sectional view of the principal part of the multilayer wiring board after interlayer connection in one embodiment of the present invention (A) Main part sectional drawing of the single-sided copper clad laminated board with the adhesive layer which is a raw material in one embodiment of this invention, (b) One side with the adhesive layer in which the copper wiring layer in one embodiment of this invention was formed Cross-sectional view of the main part of the wiring board, (c) Cross-sectional view of the main part of the single-sided wiring board with an adhesive layer in which the through hole is formed in the embodiment of the present invention, (d) Blind via in the embodiment of the present invention Cross-sectional view of the main part of the multilayer wiring board in which holes are formed, (e) Cross-sectional view of the main part of the double-sided wiring board after the copper core solder ball is press-fitted and deformed in one embodiment of the present invention, (f) One of the present invention Cross-sectional view of main parts of multilayer wiring board after interlayer connection on which plating film is formed in the embodiment (A) Main part sectional drawing of the multilayer wiring board after lamination in one embodiment of the present invention, (b) Main part sectional view of another multilayer wiring board after lamination in one embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer wiring board 2 Insulation layer 3 Copper wiring upper layer 4 Copper wiring lower layer 5 Through-hole 6 Solder conductor 7 Solder ball 8 Plating film 9 Double-sided copper clad laminated board 10 Copper foil 11 Double-sided wiring board 12 Punching die 13 Copper core solder ball DESCRIPTION OF SYMBOLS 14 Copper piece 15 Pressure upper plate 16 Pressure lower plate 17 Plating bath 18 Counter electrode 19 Single-sided copper clad laminated board with an adhesive layer 20 Adhesive layer 21 Single-sided wiring board with an adhesive layer 22 Blind via hole 23 Other single-sided wiring boards 24 Multilayer wiring Board 25 Multi-layer wiring board 26 Multi-layer wiring board 27 Multi-layer wiring board

Claims (9)

An insulating layer, a copper wiring layer laminated on both surfaces of the insulating layer, a through hole penetrating the insulating layer and at least one of the copper wiring layers, and a conductive connection between the copper wiring layers filled in the through hole A multilayer wiring board comprising a solder conductor, wherein a solder exposed surface in which a part of the solder conductor is in contact with the copper wiring layer and exposed at an outermost surface, and the copper wiring layer surface is a metal plating film A multilayer wiring board, wherein the metal plating film is made of a metal having a higher ionization tendency than the solder conductor. 2. The multilayer wiring board according to claim 1, wherein the solder conductor has a copper piece smaller than the diameter of the through hole in the core portion, and the surface is covered with a solder metal layer. The multilayer wiring board according to claim 1 or 2, wherein the metal plating film contains at least one of nickel or a nickel alloy. 4. The multilayer wiring board according to claim 1, wherein at least one kind of different metal plating film is laminated on the surface of the metal plating film. 5. The multilayer wiring board according to claim 1, wherein the metal plating film is partially plated only in a region including at least a range filled with the solder conductor. After forming a through hole that penetrates the copper wiring layer and the insulating layer at a predetermined interlayer connection position of a double-sided wiring board in which a copper wiring layer is formed on both surfaces of the insulating layer, a substantially spherical solder ball is press-fitted A solder conductor is formed by filling, and nickel plating is performed by electrolytic nickel plating on the solder exposed surface in which a part of the solder conductor is in contact with the copper wiring layer and exposed on the outermost surface. A method for producing a multilayer wiring board, comprising conducting a film between the copper wiring layers by electrodepositing a film. The double-sided wiring board is formed by bonding two single-sided wiring boards each having a copper wiring layer formed on one side of an insulating layer with an adhesive layer in an orientation in which the copper wiring layer becomes an outermost layer. Item 7. A method for producing a multilayer wiring board according to Item 6. A through-hole penetrating the copper wiring layer and the insulating layer is formed at a predetermined interlayer connection position of the single-sided wiring board having a copper wiring layer formed on one side of the insulating layer, and the copper wiring layer of the single-sided wiring board After forming a blind via hole by laminating via an adhesive layer on the surface of the copper wiring layer of another single-sided wiring board in the direction to become the outermost layer, a substantially spherical solder ball is press-fitted into the blind via hole. A solder conductor is formed on the surface of the copper wiring layer by electrolytic nickel plating between the exposed surface of the solder that is in contact with the copper wiring layer and exposed on the outermost surface. The method for producing a multilayer wiring board is characterized in that electrical conduction is obtained between the copper wiring layers by analyzing. 8. The method of manufacturing a multilayer wiring board according to claim 6, wherein the solder ball has a copper piece smaller than the diameter of the through hole in the core portion, and the surface is covered with a solder metal layer. A method for manufacturing a wiring board.

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