JP2004221432A - Circuit board and interlayer connection method of multilayer wiring circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To electrically connect conductors together disposed on both surfaces of an insulating layer with sure, with a conductive paste which is in uncured state before a heating process being hard to drop off, and to establish electrical continuity between circuit layers. <P>SOLUTION: A circuit board (1) electrically connects conductors (8) and (9) disposed on both surfaces of an insulating layer (2) with a through hole (5) formed in the insulating layer (2) in between, through a conductive paste (7) which is packed in the through hole (5) and cured. A core member (6) that contacts at least to one of the conductors (8) and (9) is provided in the through hole (5). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circuit board that can be used to form, for example, a printed circuit board having a multilayer wiring structure, that is, a multilayer wiring circuit board, and to an interlayer connection method for the multilayer wiring circuit board.
[0002]
[Prior art]
Generally, paste IVH (Interstitial Via Hole), which uses a conductive resin to connect between adjacent circuit layers of a multilayer wiring circuit board, is lower in cost and shorter delivery time than a conventional plating method (PTH, LVH). A multilayer wiring circuit board can be manufactured, and a via-on-via (Via on Via) and pad-on-via (Pad on Via) structure can be realized, which greatly contributes to higher density of wiring and mounting.
[0003]
FIG. 12 shows an example of a manufacturing process of the multilayer wiring circuit board 220 using the paste IVH. As shown in FIG. 12, a hole (IVH) 225 having the circuit layer 223 as a bottom surface is formed in the insulating layer 222 of the laminate 221 having the circuit layer 223 on one surface of the insulating layer 222, and a conductive layer is formed in the hole (IVH) 225. The paste 227 is filled, a plurality of laminated boards 221 are stacked so that the holes are vertically overlapped, and a heat treatment is performed while pressing, so that the circuit layers 223 through the conductive paste 227 of each laminated board 221 are formed. 223,... Are conducted.
[0004]
[Patent Document 1]
JP-A-2002-94233 [0005]
[Patent Document 2]
Japanese Patent Application Laid-Open No. 7-147664
[Problems to be solved by the invention]
However, the conductive paste 227 before the laminating / heating step is in an uncured state and is in contact only with the inner peripheral surface of the hole (IVH) 225 in the height direction. 13, for example, as shown in FIG. 13, a part of the upper portion of the conductive paste 227 filled in the hole (IVH) 225 easily falls off. When even a part of the conductive paste 227 falls off, the amount of the conductive paste 227 necessary for establishing conduction between the circuit layers 223, 223,... There was a problem that caused.
[0007]
An object of the present invention is to eliminate the above-mentioned problems of the conventional one, and the conductive paste in the uncured state before the heating step does not easily fall off, thereby allowing the conductors arranged on both surfaces of the insulating layer to be separated. To provide a circuit board capable of reliably and electrically connecting the circuit boards to each other, and a method for connecting layers of a multilayer wiring circuit board capable of ensuring reliable conduction between circuit layers.
[0008]
[Means for Solving the Problems]
The present invention solves the above-mentioned problem, and the invention according to claim 1 fills a conductor disposed on both surfaces of the insulating layer with a through-hole formed in the insulating layer therebetween in the through-hole. A circuit board electrically connected to each other via a conductive paste cured by curing, wherein a core member in contact with at least one of the conductors is provided in the through hole.
[0009]
The invention according to claim 2 is to form a through hole in contact with a conductor of the circuit layer in an insulating layer having a circuit layer on one surface, fill the conductive paste, and stack another conductor on an open end of the through hole. In a circuit board that electrically connects the two conductors via the conductive paste by curing the conductive paste, a circuit board provided with a core member in contact with the conductor of the circuit layer in the through hole. is there.
[0010]
The invention according to claim 3 is the circuit board according to claim 1 or 2, wherein the core member is formed at a height substantially equal to a thickness of the insulating layer.
[0011]
The invention according to claim 4 is a method for connecting circuit layers of a multilayer wiring circuit board in which at least two laminated boards each having a circuit layer on one side of an insulating layer are laminated, wherein the insulating layer of the laminated board has a circuit layer. With the bottom as a bottom, an annular hole having a core near the center is formed, and the conductive paste is filled in the annular hole until the upper surface thereof is higher than the upper surface of the insulating layer. This is an interlayer connection method for a multilayer wiring circuit board in which circuit layers are stacked, and a heat treatment is performed while pressing both laminated boards, so that the circuit layers are electrically connected via a conductive paste that is hardened in the annular holes.
[0012]
The invention according to claim 5 is a method for connecting circuit layers of a multilayer wiring circuit board in which at least two laminated boards each having a circuit layer on one side of an insulating layer are laminated, wherein the insulating layer of the laminated board has a circuit layer. Is formed as a bottom surface, an annular hole having a core having a height substantially equal to the thickness of the insulating layer is formed near the center, and the conductive paste is filled in the annular hole until the upper surface is higher than the upper surface of the insulating layer. Then, a conductive paste is also placed on the upper surface of the core, a circuit layer of another laminated board is laminated on the open end of the annular hole, and heat treatment is performed while pressing both laminated boards. And an interlayer connection method for a multilayer wiring circuit board for electrically connecting between circuit layers via a conductive paste which is cured on the upper surface of the core.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing an embodiment of a circuit board according to the present invention. The circuit board 1 has conductors arranged on both sides of an insulating layer 2 with a through hole 5 formed in the insulating layer 2 interposed therebetween. 8 and 9 are electrically connected to each other via a conductive paste 7 filled and cured in the through hole 5, and a core member 6 in contact with at least one of the conductors 8 in the through hole 5. Is provided.
[0014]
Specifically, as shown in FIGS. 2 and 3, the circuit board 1 is formed by forming a through-hole 5 in contact with a conductor 8 of the circuit layer 3 in an insulating layer 2 having a circuit layer 3 on one surface and forming a conductive paste 7 on the insulating layer 2. Is filled, another conductor 9 is overlapped on the open end of the through-hole 5, and the conductive paste 7 is cured, thereby electrically connecting the conductors 8 and 9 via the conductive paste 7. In the through hole 5, a core member 6 which is in contact with the conductor 8 of the circuit layer 3 is provided. The core member 6 is preferably formed at a height substantially equal to the thickness of the insulating layer 2, but may be slightly lower. When the conductive paste 7 is filled in the through holes 5, a film 10 such as a masking tape made of PET (polyethylene terephthalate) is pasted on the upper surface of the insulating layer 2 and the upper surface of the core member 6, and after filling, By peeling 10, the conductive paste 7 is filled until the upper surface is higher than the upper surface of the insulating layer 2. Then, while another conductor 9 is placed on the upper surface of the conductive paste 7 and pressed, a heat treatment is performed to cure the conductive paste 7.
[0015]
As described above, since the core member 6 is provided in the through hole 5 of the circuit board 1, the through hole 5 and the core member 6 can be collectively referred to as the annular hole 4. Therefore, it can be said that the insulating layer 2 of the circuit board 1 has the circuit layer 3 as the bottom surface and the annular hole 4 including the through hole 5 and the core member 6.
[0016]
In order to form such an annular hole 4 in the insulating layer 2, as shown in FIG. 4, the annular hole 4 is left by machining such as laser or chemical processing such as etching while leaving the core member 6 near the center. Can be formed directly (instead of forming the core member 6 after the formation of the through-hole 5). In this case, if a film 10 such as a masking tape made of PET (polyethylene terephthalate) is attached to the surface of the insulating layer 2 before processing, an annular hole is also formed in the film 10 in the processing step of the annular hole 4. This can be used as it is as the film 10 when the conductive paste 7 is filled.
[0017]
In order to form the annular hole 4 in the insulating layer 2, as shown in FIG. 5, a through hole 5 is first formed in the insulating layer 2 by appropriate processing, and a photosensitive resin 11 is applied to the By performing the development processing, the core member 6 made of the photosensitive resin 11 can be formed at a predetermined position in the through hole 5. Further, as shown in FIG. 6, by exposing and developing the photosensitive resin 11 using the photosensitive resin 11, the annular hole 4 can be directly formed at the same time as forming the insulating layer 2 itself.
[0018]
To form the annular hole 4 in the insulating layer 2, as shown in FIG. 7, a through hole 5 is first formed in the insulating layer 2 by appropriate processing, and a core made of a columnar resin formed by punching or the like. The member 6 can be attached to the circuit layer 3 at a predetermined position in the through hole 5.
[0019]
Such a circuit board 1 can be configured independently and can be applied to, for example, mounting of electronic components and the like, and a multilayer wiring circuit board can be configured by stacking several layers. Therefore, a method of connecting the layers of the multilayer wiring circuit board will be described below, and a method of manufacturing the circuit board 1 will also be described, although the method partially overlaps the above description using FIG.
[0020]
FIG. 8 is an explanatory view showing an example of a method for connecting layers of a multilayer wiring circuit board using the circuit board 1. The multilayer wiring circuit board 20 includes at least two laminated boards 21 substantially identical to the circuit board 1. The layers are laminated.
[0021]
That is, the laminated plate 21 includes the circuit layer 23 on one surface of the insulating layer 22. First, the insulating layer 22 of the laminated plate 21 has the circuit layer 23 as a bottom surface and a core (core member) 26 near the center. An annular hole 24 is formed. For forming the annular hole 24 including the through hole 25 and the core member 26, a method as shown in FIGS. 4 to 7 can be used.
[0022]
Next, the annular hole 24 is filled with the conductive paste 27 until the upper surface thereof is higher than the upper surface of the insulating layer 22. Specifically, a film 30 such as a masking tape made of PET (polyethylene terephthalate) is adhered to the upper surface of the insulating layer 22 and the upper surface of the core (core member) 26, and the annular hole 24 is filled with the conductive paste 27 in this state. After that, by peeling the film 30, the filling can be made higher than the upper surface of the insulating layer 22 by an amount corresponding to the thickness of the film 30. The same applies to the case where the conductive paste 7 is filled in the annular hole 4 of the circuit board 1.
[0023]
The circuit layer 23 of another laminated plate 21 is positioned and laminated on the open end of the annular hole 24 from the laminated plate 21 thus prepared, and heat treatment is performed while pressing both laminated plates 21, 21. By doing so, the circuit layers 23 are electrically connected via the conductive paste 27 that is hardened in the annular hole 24. The same applies to a case where another conductor 9 is overlapped on the open end of the annular hole 4 of the circuit board 1 and the conductors 8 and 9 are electrically connected via the conductive paste 7.
[0024]
The conductive paste 27 filled in the annular hole 24 not only contacts the inner peripheral surface of the through hole 25 but also contacts the outer peripheral surface of the core (core member) 26. The contact area with the laminated plate 21 is larger than in the case where it is in contact only with the inner peripheral surface of the substrate. Avoidance. Thereby, electrical connection (interlayer connection) between the circuit layers 23, 23 is reliably realized. This is the same in the case of electrically connecting both conductors 8 and 9 by the conductive paste 7 of the circuit board 1.
[0025]
Further, the amount of the conductive paste 27 required to realize the electrical connection (interlayer connection) between the circuit layers 23 and 23 is determined by the height of the conductive paste 27 protruding from the upper surface of the insulating layer 22 (that is, the film 30). Therefore, by properly selecting the thickness of the film 30 to be used, the reliability of the interlayer connection between the circuit layers 23 and 23 is guaranteed. This also applies to the height of the conductive paste 7 protruding from the upper surface of the insulating layer 2 of the circuit board 1 (thickness of the film 10 to be used) and the reliability of the electrical connection between the conductors 8 and 9. It is.
[0026]
FIG. 9 is an explanatory view showing another example of the interlayer connection method of the multilayer wiring circuit board. This multilayer wiring circuit board 120 is almost the same as the multilayer wiring circuit board 20 of FIG. Better connection reliability. Therefore, by configuring the circuit board 101 that is substantially the same as the laminated board 121 used for the multilayer wiring circuit board 120, the reliability of the electrical connection between the conductors 108 and 109 can be further improved as compared with the circuit board 1. Is possible. A description will be given of a method of connecting the layers of the multilayer wiring circuit board 120 together with the method of manufacturing the circuit board 101.
[0027]
This multilayer wiring circuit board 120 is configured by laminating at least two laminated boards 121 each having a circuit layer 123 on one surface of an insulating layer 122. First, the insulating layer 122 of the laminated board 121 has the circuit layer 123 as a bottom surface. An annular hole 124 having a core (core member) 126 having a height substantially equal to the thickness of the insulating layer 122 is formed near the center. The method shown in FIGS. 4 to 7 can be used to form the annular hole 124 including the through hole 125 and the core member 126.
[0028]
Next, the annular hole 124 is filled with the conductive paste 127 until the upper surface thereof is higher than the upper surface of the insulating layer 122. Specifically, a film 130 such as a masking tape made of PET (polyethylene terephthalate) is stuck on the upper surface of the insulating layer 122 except for the core (core member) 126, and in this state, the annular hole 124 is filled with the conductive paste 127. At this time, since the film 130 is not stuck on the upper surface of the core (core member) 126, the conductive paste 127 is applied to the upper surface of the core (core member) 126 in addition to the annular hole 124 and the film thickness above it. Is filled higher than the upper surface of the insulating layer 122 by an amount corresponding to the thickness of the film 130. Therefore, in the through hole 125 of the annular hole 124, a projection A made of the conductive paste 127 corresponding to the film thickness is formed on the upper surface of the core (core member) 126. In addition, since the height of the core (core member) 126 is substantially equal to the thickness of the insulating layer 122, the protrusion A of the conductive paste 127 on the core (core member) 126 is It will surely protrude upward from the upper surface. The same applies to the case where the conductive paste 107 is filled in the annular hole 104 of the circuit board 101.
[0029]
When the filling of the conductive paste 127 is completed in this manner, the film 130 is peeled off, and the circuit layer 123 of another laminated plate 121 is positioned and laminated on the laminated plate 121 at the open end of the annular hole 124. By performing a heat treatment while pressing the plates 121, 121, the circuit layers 123, 123 are electrically connected to each other via the conductive paste 127 that is hardened in the annular hole 124 and on the upper surface of the core (core member) 126. At this time, the conductive paste 127 filled in the annular hole 124 is not only in contact with the inner peripheral surface of the through hole 125 but also with the outer peripheral surface of the core member 126. The contact area with the laminated plate 121 is larger than in the case where it is in contact only with the peripheral surface, and therefore, for example, the behavior is kept stable even in the transport process, and the inconvenience that the upper part is partially dropped is substantially eliminated. Be avoided. In addition, the protrusion A of the conductive paste 127 on the core (core member) 126 projecting upward from the upper surface of the insulating layer 122 is securely and tightly joined to the circuit layer 123 of another laminated board 121 to be laminated. 11, the conductivity is greatly improved as compared with the case where the conductive paste 127 on the core (core member) 126 is not present, and therefore, for example, as shown in FIG. Even if there is a problem that the conductive paste 127 located above the annular hole 124 partially falls off, as long as there is a protrusion A by the conductive paste 127 on the core (core member) 126, the circuit The reliability of the electrical connection (layer connection) between the layers 123, 123 is guaranteed. This is the same in the case of the circuit board 101 in which the protrusion A of the conductive paste 107 on the core member 106 protrudes upward from the upper surface of the insulating layer 102.
[0030]
【The invention's effect】
As described above, according to the present invention, the conductors arranged on both surfaces of the insulating layer with the through hole formed in the insulating layer therebetween are electrically connected to each other via the conductive paste filled in the through hole and cured. In the circuit board to be connected to, the core member in contact with at least one of the conductors is provided in the through hole, so that the conductive paste in an uncured state before the heating step does not easily fall off, thereby There is an effect that the conductors arranged on both sides of the layer can be reliably electrically connected to each other.
[0031]
The present invention also provides an insulating layer of a laminate having a circuit layer on one surface of an insulating layer, wherein the circuit layer is formed as a bottom surface, an annular hole having a core is formed near the center, and a conductive paste is insulated on the annular hole. Filled to a level higher than the upper surface of the layer, laminated the circuit layer of another laminated board on the open end of the annular hole, and heat-treated while pressing both laminated boards, through the conductive paste that hardens in the annular hole As a result, the conductive paste in an uncured state before the heating step does not easily fall off, thereby providing an effect that reliable conduction between the circuit layers can be obtained. is there.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a partially expanded cross section of an embodiment of a circuit board according to the present invention.
FIG. 2 is a sectional view specifically showing the circuit board of FIG. 1 together with a manufacturing process.
FIG. 3 is a plan view of the circuit board of FIG. 2 in a manufacturing process.
FIG. 4 is a cross-sectional view illustrating a method of forming an annular hole.
FIG. 5 is a cross-sectional view showing another method for forming an annular hole.
FIG. 6 is a sectional view showing still another method of forming the annular hole.
FIG. 7 is a cross-sectional view showing another method for forming an annular hole.
FIG. 8 is an explanatory diagram showing in cross section an example of a method of connecting layers of a multilayer wiring circuit board according to the present invention.
FIG. 9 is an explanatory view showing a cross section of another example of the interlayer connection method of the multilayer wiring circuit board according to the present invention, and also shows a manufacturing process of a circuit board substantially the same as the laminated board used therein.
FIG. 10 is a plan view of the manufacturing process of the laminate / circuit board of FIG. 9;
FIG. 11 is a cross-sectional view assuming that a part of the conductive paste has dropped off in the manufacturing process of the laminate / circuit board of FIG. 9;
FIG. 12 is an explanatory view showing in cross section an example of a conventional interlayer connection method for a multilayer wiring circuit board.
FIG. 13 is a cross-sectional view showing a state in which a conductive paste has partially dropped off in the manufacturing process of the laminated board of FIG.
[Explanation of symbols]
1,101 circuit board 2,22,102,122 insulating layer 3,23,103,123 circuit layer 4,24,104,124 annular hole 5,25,105,125 through hole 6,26,106,126 core ( Core material)
7, 27, 107, 127 Conductive paste 8, 9, 108, 109 Conductor 10, 30, 110, 130 Film 11 Photosensitive resin 20, 120 Multilayer wiring circuit board 21, 121 Laminated board

Claims (5)

A circuit board that electrically connects conductors disposed on both surfaces of the insulating layer with a through hole formed in the insulating layer therebetween through a conductive paste that is filled into the through hole and cured.
A circuit board, wherein a core member in contact with at least one of the conductors is provided in the through hole. Forming a through-hole in contact with a conductor of the circuit layer in an insulating layer having a circuit layer on one side, filling the conductive paste, and overlaying another conductor on the open end of the through-hole to cure the conductive paste. In a circuit board that electrically connects the two conductors via the conductive paste,
A circuit board, wherein a core member in contact with a conductor of the circuit layer is provided in the through hole. The circuit board according to claim 1, wherein the core member is formed at a height substantially equal to a thickness of the insulating layer. A method for connecting between circuit layers of a multilayer wiring circuit board in which at least two laminated boards each having a circuit layer on one surface of an insulating layer are laminated,
In the insulating layer of the laminate, the circuit layer is a bottom surface, an annular hole having a core near the center is formed,
Fill the annular hole with conductive paste until its upper surface is higher than the upper surface of the insulating layer,
By laminating a circuit layer of another laminated board on the open end of the annular hole, and heating the two laminated boards while pressing them, the circuit layers are electrically connected via a conductive paste which hardens in the annular hole. Do
An interlayer connection method for a multilayer wiring circuit board, characterized in that: A method for connecting between circuit layers of a multilayer wiring circuit board in which at least two laminated boards each having a circuit layer on one surface of an insulating layer are laminated,
In the insulating layer of the laminate, the circuit layer is formed as a bottom surface, and an annular hole having a core having a height substantially equal to the thickness of the insulating layer is formed near the center,
By filling the annular hole with conductive paste until the upper surface thereof is higher than the upper surface of the insulating layer, the conductive paste is also arranged on the upper surface of the core,
By laminating a circuit layer of another laminated board on the open end of the annular hole, and by performing a heat treatment while pressing both laminated boards, between the circuit layers via a conductive paste that is cured in the annular hole and on the upper surface of the core. Electrical connection,
An interlayer connection method for a multilayer wiring circuit board, characterized in that:

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