JP2007242872A - Multilayer printed wiring board, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board and a manufacturing method thereof which can be manufactured by a cheap and simple method and with a high yield. <P>SOLUTION: A double-sided flexible printed circuit board 1 for inner layers has conductor-circuit layers whereon conductor circuits 10 are formed. Also, bumps 8 of conductor members connected electrically with the conductor circuits 10 are formed to protrude them from the conductor circuits 10. Further, the double-sided flexible printed circuit board 1 and other conductor-circuit layers 22 are laminated via adhesive agents 23. The adhesive agent 23 is an anisotropic conductive adhesive agent containing conductive micro-particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multilayer printed wiring board used as a component of an electronic device and a method for manufacturing the same.

  In recent years, in the field of electronic equipment, with the increase in the density of electronic equipment, multilayered printed wiring boards used as parts of electronic equipment have progressed. As such multilayer printed wiring boards, flexible prints having a multilayer structure have been developed. A wiring board or a rigid flex printed wiring board that is a composite substrate of a flexible printed wiring board and a rigid printed wiring board is used.

  Here, conventionally, various methods have been proposed for manufacturing these multilayer printed wiring boards. For example, a step of pressurizing and heating a copper foil via a resin layer on a surface of a circuit board on which a conductor circuit with a predetermined conductor pattern and a connection pad are formed on a base material, and laminating the connection pad A step of selectively removing the copper foil at a corresponding position to form a connection land, and a step of using a laser to open a via hole in a resin layer at a position corresponding to the connection pad and exposing the connection pad And by applying metal plating (electrolytic copper plating) to the via hole, the metal plating layer is deposited, and the connection land and the connection pad are electrically connected. By repeating these steps, the circuit layer A method for manufacturing a build-up type multilayer printed wiring board formed by stacking layers is disclosed (for example, see Patent Document 1).

Further, the first copper foil is etched to form a predetermined conductor pattern, and the surface of the conductor pattern of the composite metal foil provided between the first and second copper layers is filled with a filler. Irradiating the thermosetting insulating resin and the organic film with a laser, a step of forming a thermosetting insulating resin layer containing the composition, a step of providing a peelable organic film on the surface of the thermosetting insulating resin layer, Forming a via hole reaching the surface of the conductor pattern, filling the via hole with a conductive paste, creating a multilayer wiring board material, peeling the organic film, and forming a through hole. Stack the inner layer circuit board so that the thermosetting insulating resin layer of the multilayer wiring board material is in contact with it, align the connection position of the conductive paste and the inner layer circuit board, and press and heat to integrate the layers. From the process Ri, by repeating these steps, the production method of the buildup type multilayer printed wiring board formed by stacking a circuit layer is disclosed (e.g., see Patent Document 2).
JP-A-8-279678 JP-A-11-261219

  However, in the manufacturing method described in Patent Document 1, when the circuit layers are stacked and formed, it is necessary to form a metal plating layer and a connection land for electrically connecting each circuit layer. There has been a problem that the structure of the multilayer printed wiring board becomes complicated. In addition, the circuit layer stacking process by pressurization and heating and the process of forming the metal plating layer and the connection land must be repeated many times, which complicates the manufacturing process and increases the cost. there were.

  In addition, in the manufacturing method described in Patent Document 2, it is necessary to form via holes for filling the conductive paste. When the circuit layers are stacked and formed, the via holes are formed and filled with the conductive paste. Therefore, the manufacturing process is complicated and the cost is increased.

  Furthermore, in the above-described conventional manufacturing method, if a patterning failure occurs in any of the manufacturing processes, the entire multilayer printed wiring board on which the patterning failure portion is laminated becomes a defective product. There was a problem that the yield in the process would decrease.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a multilayer printed wiring board that can be manufactured by a low-cost and simple method and that can be manufactured at a high yield, and a manufacturing method thereof. .

  In order to achieve the above object, the invention according to claim 1 is a multilayer printed wiring comprising a plurality of conductor circuit layers in which conductor circuits are formed, and the plurality of conductor circuit layers are laminated via an adhesive layer. In the board, the adhesive layer is an anisotropic conductive adhesive containing conductive fine particles, and a conductor member electrically connected on the conductor circuit is formed on the surface of the conductor circuit layer so as to protrude. It is characterized by that.

  According to this configuration, it is possible to conduct conductive connection between a large number of conductor members (or between conductor circuits and conductor members) by the anisotropic conductive adhesive containing conductive fine particles. Therefore, unlike the prior art described above, there is no need to form a metal plating layer and a connection land for electrically connecting each conductor circuit layer and a via hole for filling a conductive paste. As a result, since the structure of the multilayer printed wiring board is simplified, the multilayer printed wiring board can be manufactured by an inexpensive and simple process. Further, since the connection of the conductor circuit and the adhesion of the conductor circuit layer can be made with the same member, the manufacturing cost can be further reduced.

  In addition, since the presence or absence of a defective portion can be inspected before laminating each conductor circuit layer via the adhesive layer, only good products can be laminated at once. Therefore, a multilayer printed wiring board can be manufactured with a high yield. Furthermore, when laminating each conductor circuit layer via an adhesive layer by heating and pressurization, it is possible to correct the height variation of the conductor member and electrically connect each conductor circuit. Become.

  A second aspect of the present invention is the multilayer printed wiring board according to the first aspect, wherein the conductive fine particles are oriented in the thickness direction of the adhesive layer. According to this configuration, the low conductive resistance in the thickness direction of the anisotropic conductive adhesive is maintained while maintaining insulation between adjacent conductor members by the high conductive resistance in the surface direction of the anisotropic conductive adhesive and preventing a short circuit. Thus, a large number of conductor members (or conductor circuit-conductor members) can be electrically conductively connected to each other at a low pressure, and at a time.

  Invention of Claim 3 is the multilayer printed wiring board of Claim 1 or Claim 2, Comprising: Conductive microparticles have a metal single-piece | unit with magnetism, 2 or more types of alloys which have magnetism, and magnetism It is one of a composite containing an alloy of a metal and another metal and a metal having magnetism.

  According to this configuration, the magnetic metals attract each other, so that the conductive material is easily gathered into the conductive material sandwiched between the conductor members during the melt flow, and as a result, the conductivity is improved. Become.

  In addition, the conductive fine particles of the present invention are any one of nickel, iron, cobalt, and two or more of these alloys from the viewpoint of improving conductivity and availability, as in the invention described in claim 4. It is preferable that

The invention according to claim 5 is a method for producing a multilayer printed wiring board, comprising the following steps.
a. A step of etching a conductor circuit layer formed on at least one surface of a substrate to form a conductor circuit.
b. Forming a conductive member electrically connected to the conductor circuit on the surface of the conductor circuit layer by projecting outward from the conductor circuit layer;
c. The printed circuit board for the inner layer manufactured in steps a and b and another conductor circuit layer are laminated and integrated by heating and pressurizing via an anisotropic conductive adhesive containing conductive fine particles. Process.
d. A process of etching another conductor circuit layer to form another conductor circuit.

  According to this configuration, it is possible to electrically connect a large number of conductor members with the anisotropic conductive adhesive containing conductive fine particles. Therefore, unlike the prior art described above, there is no need to form a metal plating layer and a connection land for electrically connecting each conductor circuit layer and a via hole for filling a conductive paste. As a result, since the structure of the multilayer printed wiring board is simplified, the multilayer printed wiring board can be manufactured by an inexpensive and simple process. Further, since the connection of the conductor circuit and the adhesion of the conductor circuit layer can be made with the same member, the manufacturing cost can be further reduced.

  In addition, since the presence or absence of a defective portion can be inspected before laminating each conductor circuit layer via the adhesive layer, only good products can be laminated at once. Therefore, a multilayer printed wiring board can be manufactured with a high yield. Furthermore, when laminating each conductor circuit layer via an adhesive layer by heating and pressurization, it is possible to correct the height variation of the conductor member and electrically connect each conductor circuit. Become.

  Invention of Claim 6 is a manufacturing method of the multilayer printed wiring board of Claim 5, Comprising: Conductive microparticles are orientating in the thickness direction of anisotropic conductive adhesive, It is characterized by the above-mentioned. . According to this configuration, the low conductive resistance in the thickness direction of the anisotropic conductive adhesive is maintained while maintaining insulation between adjacent conductor members by the high conductive resistance in the surface direction of the anisotropic conductive adhesive and preventing a short circuit. Thus, a large number of conductor members (or conductor circuit-conductor members) can be electrically conductively connected to each other at a low pressure, and at a time.

  The invention according to claim 7 is the method for manufacturing a multilayer printed wiring board according to claim 5 or 6, wherein the conductor member is formed by a plating method. According to this configuration, since the conductor member can be formed by a simple method, the manufacturing process of the multilayer printed wiring board can be further simplified.

  According to the present invention, a multilayer printed wiring board can be manufactured by an inexpensive and simple method and at a high yield.

  Hereinafter, a preferred embodiment of the present invention will be described. FIG. 1 is a cross-sectional view for explaining a method for producing a multilayer printed wiring board in an embodiment of the present invention, and in particular, a double-sided circuit board for an inner layer of the multilayer printed wiring board according to the present invention and a method for producing the same. FIG. FIG. 2 is a cross-sectional view for explaining a method for producing a multilayer printed wiring board according to an embodiment of the present invention, and more particularly, a diagram for explaining the multilayer printed wiring board of the present invention and the method for producing the same. .

  As a manufacturing method of the multilayer flexible printed wiring board of this invention, as shown in FIG. 1, the double-sided flexible printed circuit board 1 for inner layers is manufactured first. More specifically, as shown to Fig.1 (a), the base material 4 which provided the conductor circuit layer 3 on both surfaces of the flexible resin film 2, for example is prepared. In addition, although it is good also as a structure which provides the conductor circuit layer 3 through an adhesive bond layer (not shown), considering the flexibility and flexibility of the flexible printed circuit board 1, it is resin without using an adhesive bond layer. The conductive circuit layer 3 is preferably provided on both surfaces of the film 2.

  As the resin film 2 constituting the substrate 4, a film made of a resin material having excellent flexibility is used. As such a resin film, for example, any resin film having versatility for a flexible printed wiring board, such as a polyester film, can be used. In particular, it is preferable to have high heat resistance in addition to flexibility in consideration of the pressurization and heating process described later. As such a resin film, for example, a polyamide-based resin film, A polyimide resin film such as polyimide or polyamideimide is preferably used. Moreover, as a metal foil which comprises the conductor circuit layer 3, a copper foil is used suitably.

Next, as shown in FIG. 1B, a through hole (hereinafter referred to as “through hole”) 5 is formed in the base material 4 using a drill, a CO ₂ laser (YAG laser), or the like. Next, as shown in FIG. 1C, by providing a plating resist 6 on the surface of the conductor circuit layer 3 and performing a plating treatment, the through hole 5 is formed as shown in FIG. The plating part 7 is formed on a part of the inner surface and the surface of the conductor circuit layer 3, and the conductor circuit layer 3 provided on both surfaces of the resin film 2 is electrically connected, and on the surface of the conductor circuit layer 3, A bump 8 that is a conductor member is formed. That is, in the present embodiment, the bumps 8 are formed at the same time as the plating part 7 by a plating process for forming the plating part 7.

  In addition, as a formation method of the plating part 7 and the bump 8, for example, an electrolytic copper plating method or an electroless copper plating method can be used. At this time, the bumps 8 are formed so as to protrude from the surface of the conductor circuit layer 3. More specifically, as shown in FIG. 1 (d), it is formed to protrude outward from the conductor circuit layer 3 provided on both surfaces of the resin film 2.

  Further, as the conductor member, for example, copper, nickel, gold, an alloy of tin and lead (for example, solder containing 95 wt% or more of tin) or the like can be used. By using these metals, it is possible to form the bumps 8 for electrical connection with a material that is highly versatile and easily available.

  Next, as shown in FIG. 1 (e), an etching resist 9 is provided, and etching is performed by an ordinary method to remove unnecessary portions of the conductor circuit layer 3, and a plurality of the resists shown in FIG. Conductor circuit 10 is formed. At this time, in the present embodiment, as shown in FIG. 1 (f), the bump 8, which is the above-described conductor member, is electrically connected on the conductor circuit 10.

  The double-sided flexible printed circuit board 1 for the inner layer is manufactured by the above process. Next, a multilayer printed wiring board is manufactured using the double-sided flexible printed circuit board 1 for the inner layer.

  Here, as a multilayer printed wiring board in which a plurality of conductor circuit layers on which conductor circuits are formed are laminated via an adhesive layer, here, two double-sided flexible printed circuit boards 1 for inner layers, and this double-sided flexible printed circuit A multilayer flexible printed wiring board in which a conductor circuit layer is laminated on the surface of the substrate 1 will be described as an example.

  First, as shown in FIG. 2A, an adhesive layer 23 is provided between two double-sided flexible printed circuit boards 1 for inner layers and between the double-sided flexible printed circuit board 1 and another conductor circuit layer 22. Pinch. Next, as shown in FIG. 2B, the double-sided flexible printed circuit board 1 and the other conductor circuit layer 22 are laminated via the adhesive layer 23 by heating and pressing. Then, as shown in FIG. 2 (c), the other conductor circuit layer 22 laminated on the double-sided flexible printed circuit board 1 is etched to form another conductor circuit 24, whereby the multilayer flexible print of the present invention is formed. The wiring board 20 is manufactured.

  Here, in this embodiment, as shown in FIG. 3, an anisotropic conductive adhesive containing conductive fine particles 25 is used as the adhesive layer 23. As the conductive fine particles 25 used for the anisotropic conductive adhesive, for example, spherical metal fine particles or spherical resin particles plated with a metal can be used. It is also possible to use metal fine particles having a shape connected in a chain shape or a needle shape, that is, a shape having a so-called large aspect ratio.

  As the adhesive layer 23, an anisotropic conductive adhesive containing conductive fine particles 25 is used, and as described above, a conductor electrically connected to the surface of the conductor circuit layer 3 on the conductor circuit 10 By forming the bumps 8 that are members to protrude (to protrude outward from the conductor circuit layer 3), the anisotropic conductive adhesive containing the conductive fine particles 25 can be used between the bumps 8 (or The conductive circuit 24 and the bump 8) can be conductively connected.

  Therefore, unlike the prior art described above, there is no need to form a metal plating layer and a connection land for electrically connecting each conductor circuit layer and a via hole for filling a conductive paste. As a result, since the structure of the multilayer flexible printed wiring board 20 is simplified, the multilayer flexible printed wiring board 20 can be manufactured by an inexpensive and simple process.

  Moreover, since the connection of each conductor circuit 10 and 24 and adhesion | attachment of each conductor circuit layer 3 and 22 can be performed with the same member (namely, adhesive bond layer 23), it becomes possible to aim at reduction of manufacturing cost.

  In addition, since the presence or absence of a defective portion can be inspected before the conductor circuit layers 3 and 22 are laminated through the adhesive layer 23, it is possible to laminate only non-defective products at once. Therefore, the multilayer flexible printed wiring board 20 can be manufactured with a high yield.

  Further, when the conductor circuit layers 3 and 22 are laminated through the adhesive layer 23 by heating and pressurization, the height variation of the bumps 8 is corrected, and the conductor circuits 10 and 24 are electrically connected. It becomes possible to connect to.

  Further, as shown in FIG. 3, by passing the conductive fine particles 25 through a magnetic field applied in the thickness direction of the anisotropic conductive adhesive at the time of forming the anisotropic conductive adhesive, the thickness direction ( It can also be used by being oriented in the magnetic field direction (direction indicated by arrow X in FIG. 3).

  By arranging the conductive fine particles 25 in such an orientation, the anisotropic conductive adhesive is maintained while maintaining insulation of the bumps 8 adjacent to each other by a high conductive resistance in the surface direction of the anisotropic conductive adhesive and preventing a short circuit. Due to the low conductive resistance in the thickness direction, a large number of bumps 8 (or between the conductor circuit 24 and the bumps 8) can be electrically conductively connected at a time and independently with a small applied pressure.

  Further, as the conductive fine particles 25 to be used, metal fine particles can be used, and the metal fine particles preferably include a magnetic substance in a part thereof, a single metal having magnetism, two or more kinds of alloys having magnetism, It is preferably any one of an alloy of a metal having magnetism and another metal and a composite containing a metal having magnetism. This is because the metal having magnetism attracts each other, so that the conductive substance is likely to gather in the conductive substance sandwiched between the electrodes during the melt flow, and as a result, the conductivity is improved. . For example, from the viewpoints of improvement in conductivity and availability, nickel, iron, cobalt, and two or more kinds of alloys, etc., having a linearly connected shape can be exemplified.

  In the present embodiment, as described above, the bumps 8 are formed at the same time as the plating portion 7 by the plating process for forming the plating portion 7. By using such a method, since the conductor member can be formed by a simple method, the manufacturing process of the multilayer printed wiring board can be further simplified.

  In addition, this invention is not limited to the said embodiment, A various design change is possible based on the meaning of this invention, and they are not excluded from the scope of the present invention.

  For example, in the above-described embodiment, the double-sided flexible printed circuit board 1 in which the conductor circuit layer 3 is provided on both surfaces of the base material 4 is used as the circuit board for the inner layer, but at least one surface of the base material 4 Alternatively, a single-sided circuit board on which a conductor circuit layer is formed may be used.

  In the above-described embodiment, a flexible printed wiring board having a multilayer structure has been described as an example of the multilayer printed wiring board. However, the present invention can be applied to multilayer printed wiring boards having other laminated structures. Needless to say. For example, the present invention can be applied to a rigid flex printed wiring board that is a composite substrate of a flexible printed wiring board and a rigid printed wiring board.

  Examples of utilization of the present invention include a multilayer printed wiring board used as a component of an electronic device and a manufacturing method thereof.

1A to 1F are cross-sectional views for explaining a method for producing a multilayer printed wiring board in an embodiment of the present invention, and in particular, a double-sided circuit board for an inner layer of the multilayer printed wiring board of the present invention. It is a figure for demonstrating and its manufacturing method. 2A to 2C are cross-sectional views for explaining a method for producing a multilayer printed wiring board in an embodiment of the present invention, and in particular, a multilayer printed wiring board according to the present invention and a method for producing the same. FIG. It is the schematic for demonstrating the electroconductive fine particles used for the anisotropic conductive adhesive of the multilayer printed wiring board in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Double-sided flexible printed circuit board, 2 ... Resin film, 3 ... Conductor circuit layer, 4 ... Base material, 5 ... Through-hole (through hole), 6 ... Resist, 7 ... Plating part, 8 ... Bump, 9 ... Resist, DESCRIPTION OF SYMBOLS 10 ... Conductor circuit, 20 ... Multilayer flexible printed wiring board, 22 ... Conductor circuit layer, 23 ... Adhesive layer, 24 ... Conductor circuit, 25 ... Conductive microparticle

Claims (7)

In a multilayer printed wiring board comprising a plurality of conductor circuit layers in which conductor circuits are formed, and the plurality of conductor circuit layers are laminated via an adhesive layer,
The adhesive layer is an anisotropic conductive adhesive containing conductive fine particles, and a conductor member electrically connected to the conductor circuit is formed on the surface of the conductor circuit layer so as to protrude. A multilayer printed wiring board characterized by that.   The multilayer printed wiring board according to claim 1, wherein the conductive fine particles are oriented in a thickness direction of the adhesive layer.   The conductive fine particles are any of a simple metal having magnetism, two or more kinds of alloys having magnetism, an alloy of a metal having magnetism with another metal, and a composite containing a metal having magnetism. The multilayer printed wiring board according to claim 1 or 2.   The multilayer printed wiring board according to claim 3, wherein the conductive fine particles are any one of nickel, iron, cobalt, and two or more kinds of alloys thereof. The manufacturing method of the multilayer printed wiring board characterized by including the following processes.
a. A step of etching a conductor circuit layer formed on at least one surface of a substrate to form a conductor circuit.
b. Forming a conductor member electrically connected to the conductor circuit on the surface of the conductor circuit layer by projecting outward from the conductor circuit layer;
c. The printed circuit board for the inner layer manufactured in steps a and b and another conductor circuit layer are laminated and integrated by heating and pressurizing via an anisotropic conductive adhesive containing conductive fine particles. Process.
d. Etching the other conductor circuit layer to form another conductor circuit.   6. The method for producing a multilayer printed wiring board according to claim 5, wherein the conductive fine particles are oriented in the thickness direction of the anisotropic conductive adhesive.   The method for manufacturing a multilayer printed wiring board according to claim 5, wherein the conductor member is formed by a plating method.

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