JP2008244290A - Multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board having high reliability, even when if using an anisotropic conductive film. <P>SOLUTION: The multilayer printed wiring board is configured such that at least two printed wiring boards, each having an insulating substrate equipped with conductor circuits having different thicknesses on at least one surface of the front surface and the rear surface of the substrate are laminated, with the conductor circuits having different thicknesses made to face each other via the anisotropic conductive film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer printed wiring board, and more particularly to a multilayer printed wiring board using an anisotropic conductive film.

  Conventionally, a method of connecting terminals using an anisotropic conductive paste or an anisotropic conductive film is known. These were mainly intended only for connection between circuits via an anisotropic conductive paste or anisotropic conductive film between the protruding electrodes of the substrate.

  FIG. 6 shows such a conventional example. An anisotropic conductive film is provided between a substrate in which an interlayer connection electrode 602 is provided on an insulating substrate 601 and a substrate in which an interlayer connection electrode 602 is provided on the other insulating substrate 601. The printed circuit board 600 is laminated via a film 603 and is interlayer-connected by sandwiching conductive particles 604 between the interlayer connection electrodes 602 (see, for example, Patent Document 1).

FIG. 7 shows another conventional example. Thick circuits 702a and 702b and thin circuits 703a and 703b are formed on both surfaces of an insulating substrate 701, and the anisotropic conductive films 704a and 704b are formed on the upper and lower sides thereof. By forming the outer layer conductor circuits 706a and 706b, the conductive particles 705a and 705b are sandwiched between the inner layer thick conductor circuits 702a and 702b and the upper layer conductor circuits 706a and 706b, and conduction between the layers is obtained. This is a build-up substrate 700 (see, for example, Patent Document 2).
JP 2003-318502 A JP 2001-326469 A

  However, in the conventional example shown in FIG. 6 described above, the electrodes are merely used for interlayer connection, and are not used as a multilayer printed wiring board. In particular, it has not been assumed at all that a wiring circuit is formed on the same surface as the interlayer connection electrode.

  Further, in the conventional example shown in FIG. 7, there is a description of a build-up multilayer printed wiring board, and although the thick part of the conductive pattern of the core substrate is used as an interlayer connection, When an anisotropic conductive film is built up on a substrate, the pressure at the time of lamination does not work, so even if a thick conductive pattern is actually formed on the core substrate, stable conduction cannot be obtained. The problem that occurred. Further, when an anisotropic conductive film is used for the surface layer of the printed wiring board, there is a problem that the surface insulating layer does not have rigidity when the component is mounted and the surface is recessed when the component is mounted.

  In view of the above problems, an object of the present invention is to provide a multilayer printed wiring board having high connection reliability even when an anisotropic conductive film is used.

  In the present invention, at least two printed wiring boards each having an insulating substrate having conductor circuits with different thicknesses on at least one of the front and back surfaces face each other with the conductive circuits having different thicknesses interposed therebetween via an anisotropic conductive film. The above-mentioned problems are solved by a multilayer printed wiring board characterized by being laminated at least.

  Since the multilayer printed wiring board of the present invention has thick and thin portions of the conductor circuit on the upper and lower substrates via the anisotropic conductive film, a stable interlayer connection can be obtained between the thick portions of the conductor circuit. it can.

  In the present invention, among the conductor circuits arranged on the anisotropic conductive film side, a thin conductor circuit constitutes a wiring circuit, and a thick conductor layer constitutes an interlayer connection layer. It is characterized by that.

  Thereby, since a wiring circuit is also formed on the surface through the anisotropic conductive film, a higher-density circuit can be formed.

  Moreover, the present invention is characterized in that an insulating layer is formed between conductor circuits arranged on the anisotropic conductive film side.

  Thereby, since conductive particles do not enter between conductor circuits on the insulating substrate, insulation between circuits is maintained.

  Further, the present invention is characterized in that an insulating layer is formed on a conductor circuit disposed on the anisotropic conductive film side.

  Thereby, even if the thickness of the anisotropic conductive film is reduced, the insulation between the layers is maintained because the insulating layer is formed on the conductor circuit.

  Further, the present invention is characterized in that the outermost conductor circuit is made finer than the inner conductor circuit.

  In the present invention, since the outermost conductor circuit does not have a portion connected to the anisotropic conductive film, the outermost conductor circuit can be formed thinner, and thus can be made finer than the inner layer circuit.

  According to the present invention, even in a multilayer printed wiring board using an anisotropic conductive film, stable interlayer connectivity and insulation of a conductor circuit formed in the anisotropic conductive film can be ensured. Even if a component is mounted on the surface layer, the surface insulating layer does not have a recess, and a stable component mounting is possible.

  A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1D is a schematic cross-sectional explanatory view showing a first embodiment of the multilayer printed wiring board of the present invention.
In FIG. 1 (d), P1 is a four-layer multilayer printed wiring board according to the present invention, and is provided with a thick conductive circuit 101 and a thin conductive circuit 102 on one side of both sides of the insulating substrate. Two conductive layers 100 are laminated and arranged such that the thick conductive circuits 101 and the thin conductive circuits 102 face each other through an anisotropic conductive film 103.

  Further, the thin conductor circuit 102 constitutes a wiring circuit, while the thick conductor circuit 101 constitutes an interlayer connection layer.

Next, a method for manufacturing the multilayer printed wiring board P1 of the present invention will be described.
First, two double-sided substrates 100 shown in FIGS. 1A and 1C are prepared. Here, each double-sided board 100 includes a thick conductor circuit 101 and a thin conductor circuit 102 on one surface of the insulating substrate. Next, the anisotropic conductive film 103 shown in FIG. 1B is interposed between the double-sided substrates 100, and the thick conductive circuits 101 and the thin conductive circuits 102 of the double-sided substrate 100 are opposed to each other. By laminating the two double-sided boards 100, a four-layer printed wiring board P1 of the present invention shown in FIG.

The double-sided substrate 100 is obtained, for example, as follows.
First, a non-through hole is formed in a double-sided copper-clad laminate by laser processing, and a circuit is formed on the surface copper foil portion by a photographic method. Next, electroless copper plating is performed on the entire surface including the non-through holes, and a plating resist is formed by a photographic method except for the conductor portions that form the non-through holes and the interlayer connection. Next, electrolytic copper plating is formed on the exposed portions of the non-through holes and the plating resist. Next, the double-sided substrate 100 is obtained by removing the plating resist and flash-etching the electroless copper plating applied to the entire surface to form a circuit.

  The anisotropic conductive film 103 is made of an anisotropic conductive film, an anisotropic conductive paste, or the like, and a thermosetting resin or a thermoplastic resin is used as the binder. The conductive particles 105 contained are mainly nickel, nickel plated with gold, nickel plated with an insulating film, and the shape is spherical, flake shaped, needle And the like. In the case of a spherical shape, one having a diameter of 2 μm to 20 μm is preferably used.

As shown in FIG. 1 (d), the multilayer printed wiring board P1 of the present invention has a conductive circuit 101 portion in a stable state because the thick conductive circuit 101 portions are formed on the anisotropic conductive film 103 side. The conductor circuit 101 can be sandwiched and stable conduction can be obtained.
Moreover, the multilayer printed wiring board P1 of the present invention can obtain a rigid multilayer printed wiring board by using a reinforcing material such as glass cloth or glass fiber for the double-sided substrate 100.

  In addition, since the multilayer printed wiring board P1 of the present invention uses a laminated board as the outermost insulating layer, it does not dent even when components are mounted on the outermost conductor circuit. Further, since the upper and lower target structures are formed around the anisotropic conductive film 103, there is an effect of suppressing warpage of the substrate. In addition, since the outermost conductor circuit 106 does not have a portion connected to the anisotropic conductive film 103 and can be formed thinner, it can be made finer than the inner layer circuit.

  Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 2 (d) is a schematic cross-sectional explanatory view showing a second embodiment of the multilayer printed wiring board of the present invention.
In FIG. 2D, P2 is a four-layer multilayer printed wiring board of the present invention, except that an insulating layer 104 is formed between thin conductive circuits 102 arranged on the anisotropic conductive film 103 side. Is configured in the same manner as the multilayer printed wiring board P1 shown in FIG.

  In addition, as shown in FIGS. 2A to 2D, the multilayer printed wiring board P <b> 2 of the present invention is also laminated after an insulating layer 104 is formed in advance between the thin conductive circuits 102 of the double-sided substrate 100. The manufacturing method is the same as the manufacturing method shown in FIG.

  In the multilayer printed wiring board P1 according to the first embodiment, when the thickness of the anisotropic conductive film 103 becomes thin or the thin conductive circuit 102 on the anisotropic conductive film 103 side becomes fine In order to improve the insulation between the insulating layers between the conductor circuits and the layers, it is more desirable to provide the insulating layer 104 between the conductor circuits of the inner layer as in the second embodiment.

  Next, a third embodiment of the present invention will be described with reference to FIGS.

FIG. 3 (d) is a schematic cross-sectional explanatory view showing a third embodiment of the multilayer printed wiring board of the present invention.
3 (d), P3 is an 8-layer multilayer printed wiring board of the present invention, and the multilayer printed wiring board shown in FIG. 1 is used except that a four-layer board 200 is used instead of the double-sided board 100 of FIG. The configuration is the same as P1.

Moreover, the multilayer printed wiring board P3 of the present invention is manufactured as follows.
First, as shown in FIGS. 3A and 3C, two through four-layer substrates 200 are prepared. Here, each four-layer substrate 200 includes a thick conductor circuit 201 and a thin conductor circuit 202 on one surface of the insulating substrate. Next, the anisotropic conductive film 203 shown in FIG. 3B is interposed between the four-layer substrates 200, and the conductive circuits 201 having a large thickness and the conductive circuits 202 having a small thickness are disposed between the through-four-layer substrates 200. Are stacked so that two through-four-layer substrates 200 are laminated to obtain an 8-layer multilayer printed wiring board P3 of the present invention shown in FIG.

  The plated through hole of the through four-layer substrate 200 is filled with a conductive paste, a non-conductive paste, or a filler in which an insulating resin is filled, and is plated with a lid.

  According to the multilayer printed wiring board P3 of the present invention, the conductor thickness of the land in the through hole portion on the inner layer side is formed thick, and the conductive particles contained in the anisotropic conductive film 203 are sandwiched between the thick conductor portions. Therefore, stable conduction can be obtained.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS.

FIG. 4D is a schematic cross-sectional explanatory view showing a fourth embodiment of the multilayer printed wiring board of the present invention.
In FIG. 4D, P4 is an eight-layer multilayer printed wiring board of the present invention, and an insulating layer 204 is formed between and above the thin conductive circuit 202 disposed on the anisotropic conductive film 203 side. The multi-layer printed wiring board P3 shown in FIG.

  In addition, as shown in FIGS. 4A to 4D, the multilayer printed wiring board P4 of the present invention also has an insulating layer 204 applied in advance between and above the thin conductor circuit 202 of the four-layer board 200. After the formation, the manufacturing method is the same as the manufacturing method shown in FIG.

  In the multilayer printed wiring board P3 according to the third embodiment, when the anisotropic conductive film 203 is thin or the thin conductive circuit 202 on the anisotropic conductive film 203 side is fine In order to improve the insulation between the conductor circuits and the insulation between the layers, it is more preferable to provide the insulation layer 204 between the conductor circuits of the inner layer or in the upper part thereof as in the fourth embodiment.

  Next, a fifth embodiment of the present invention will be described with reference to FIGS.

FIG. 5 (f) is a schematic cross-sectional explanatory view showing a fifth embodiment of the multilayer printed wiring board of the present invention.
In FIG. 5 (f), P5 is a six-layer multilayer printed wiring board according to the present invention, except that three double-sided substrates 300 each having an insulating layer 304 formed between the thin conductor circuits 302 and above are laminated. Is configured in the same manner as the multilayer printed wiring board P1 shown in FIG.

The multilayer printed wiring board P5 of the present invention is manufactured as follows.
First, as shown in FIGS. 5A, 5C, and 5E, three double-sided substrates 300 are prepared. Here, the double-sided board 300 shown in FIGS. 5A and 5C includes a thick conductor circuit 301 and a thin conductor circuit 302 on one surface of the insulating substrate, and a thin conductor circuit. An insulating layer 304 is formed in advance between and above 302, and a double-sided board 300 shown in FIG. 5B has a thick conductor circuit 301 and a thin conductor circuit on both front and back surfaces of the insulating board. 302, and an insulating layer 304 is formed in advance between and above the thin conductor circuit 302. Next, the anisotropic conductive film 303 shown in FIGS. 5B and 5D is interposed between the double-sided substrates 300, and the thick conductive circuits 301 of the double-sided substrates 300 and the thin conductive circuits are provided. The multilayer printed wiring board P5 of the present invention having six layers shown in FIG. 5 (f) is obtained by laminating the three double-sided substrates 300 with the 302s facing each other.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic cross-sectional process explanatory drawing which shows the 1st manufacture example of this invention multilayer printed wiring board. The schematic cross-sectional process explanatory drawing which shows the 2nd manufacturing example of this invention multilayer printed wiring board. FIG. 6 is a schematic cross-sectional process explanatory diagram showing a third production example of the multilayer printed wiring board of the present invention. FIG. 10 is a schematic cross-sectional process explanatory diagram showing a fourth production example of the multilayer printed wiring board of the present invention. FIG. 10 is a schematic cross-sectional process explanatory diagram illustrating a fifth production example of the multilayer printed wiring board of the present invention. Schematic cross-sectional explanatory drawing of the conventional multilayer printed wiring board. The schematic cross-section explanatory drawing of another conventional multilayer printed wiring board.

Explanation of symbols

100, 300: Double-sided substrate 101, 201, 301: Thick conductor circuit 102, 202, 302: Thin conductor circuit 103, 203, 303: Anisotropic conductive film 104, 204, 304: Insulating layer 105: Conductive Particle 106: outermost conductor circuit 200: four-layer substrate P1, P2: multilayer printed wiring board of the present invention (four layers)
P3, P4: Multilayer printed wiring board of the present invention (8 layers)
P5: Multilayer printed wiring board of the present invention (six layers)
600: Conventional printed circuit board 601, 701: Insulating substrate 602: Electrodes 603, 704a, 704b: Anisotropic conductive films 604, 705a, 705b: Conductive particles 700: Conventional build-up substrates 702a, 702b: Thick conductor circuits 703a, 703b: thin conductor circuits 706a, 706b: outermost conductor circuits

Claims (5)

  At least two printed wiring boards having an insulating substrate provided with conductor circuits having different thicknesses on at least one surface of the front and back surfaces are arranged so that the conductor circuits having different thicknesses face each other through an anisotropic conductive film. A multilayer printed wiring board characterized by being made.   The thin conductor circuit among the conductor circuits arranged on the anisotropic conductive film side constitutes a wiring circuit, and the thick conductor circuit constitutes an interlayer connection layer. Item 11. A multilayer printed wiring board according to Item 1.   The multilayer printed wiring board according to claim 1, wherein an insulating layer is formed between conductor circuits arranged on the anisotropic conductive film side.   The multilayer printed wiring board according to claim 1, wherein an insulating layer is formed on the conductor circuit disposed on the anisotropic conductive film side.   The multilayer printed wiring board according to any one of claims 1 to 4, wherein the outermost conductor circuit is made finer than the inner layer conductor circuit.

Images