JP2003338691A - Circuit board and multilayer board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology to eliminate the increase of the thickness of a local area in the vicinity of a land when multiple layers are laminated on a circuit board which includes via holes and so-called inner via holes filled with conductive resin compounds for wiring to connect conductor circuits of front and rear surfaces and is formed in the multiple layers by the lamination of a plurality of layers. <P>SOLUTION: There is provided a circuit board 11 wherein a land 4, which is connected to a projected portion 106 of a conductive resin composition 105 filling a hole 104 formed in the circuit board 101 laminated on a conductor circuit 3, is included to the conductor circuit 3 on the board 2 composed of an insulating material, and a projected portion absorbing part 5 in the structure of a recess to accommodate the projected portion 106 is also provided at the land 4 or its neighboring area. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board (or package board) on which electronic components are mounted, and a multilayer board in which two or more circuit boards are laminated in order to improve surface mounting density.

[0002]

2. Description of the Related Art As electronic devices have become lighter, thinner and smaller, semiconductor chips have become smaller, and terminals have a narrower pitch, the mounting area of electronic components and the fineness of wiring have been promoted even in printed circuit boards. There is. At the same time, in information-related equipment, it is required to shorten the distance of the wiring that connects the parts in response to the widening of the signal frequency, and the multilayered circuit board to achieve high density and high performance. Is becoming an indispensable technology.

In such a multi-layer substrate, a key technique is to form a circuit for electrically connecting the layers, which is not present in the conventional planar circuit. As a means for interlayer connection in this multilayer substrate, there is a method of forming via holes by plating. However, in the case of the via hole formed by this plating, it takes a long time to form the via hole and the productivity is poor.

Therefore, an increasing number of circuit boards have adopted a method of filling a via hole with a conductive resin composition (conductive paste) (Japanese Patent Laid-Open No. 06-302957, etc.). This conductive resin composition can be filled in via holes at high speed by a printing method, and has significantly higher productivity than forming via holes by plating.

[0005]

However, when the method of filling the via hole with the conductive resin composition is adopted, the via hole protruding from the lower surface of the upper circuit board when the circuit boards are bonded to each other to form a multilayer structure. The conductive resin composition portion filled in is bonded to the land portion on the upper surface of the lower circuit board, but at this time, the thickness in the vicinity of the land portion becomes large, and the smoothness of the multilayer substrate after lamination is poor. There was a problem. When the thickness near the land part increases locally, the force that pulls the circuit board around the land part acts,
There is also a problem that the reliability of the electrical connection portion is low due to the misalignment of the circuit boards that are bonded to each other above and below.
In addition, the conductive resin composition extruded from the land portion to the periphery does not come into contact with the adjacent land portion or the non-connecting portion of the wiring portion to cause electrical conduction, so that the land portion and the wiring portion are electrically connected. It was necessary to take measures such as securing a sufficient distance between them. In view of the above problems, the present invention provides a circuit board having a via hole or a so-called inner via hole filled with a conductive resin composition, and when a plurality of layers are laminated to facilitate smoothness of the multilayer board after lamination. An object is to provide a circuit board and a multilayer board that can be secured.

[0006]

In order to achieve the above object, the present invention employs the following configurations. A circuit board according to the present invention is the circuit board of a conductive resin composition, wherein a conductor circuit is formed on one surface or both surfaces of a substrate made of an insulating material, and a through wiring of the circuit board laminated on the conductor circuit is formed. A circuit board having a land portion connected to a protruding portion protruding from the land portion or an adjacent portion thereof, the protruding portion absorbing portion having a hollow structure for accommodating the protruding portion of the conductive resin composition is provided. It is characterized by being As the protruding portion absorbing portion, any one of a structure having an opening size larger than the maximum outer diameter of the protruding portion of the conductive resin composition and a structure having a volume larger than the volume of the protruding portion of the conductive resin composition. It is preferable to employ one or both. Further, as the protruding portion absorbing portion, it is also possible to adopt a configuration in which at least a part of the protruding portion absorbing portion is located on a conductor forming a land portion, or a configuration formed in a mortar-shaped hollow structure. A multilayer board according to the present invention is characterized by being formed by laminating a plurality of circuit boards including the circuit board according to the present invention.

According to the present invention, the protruding portion of the conductive resin composition protruding from the surface (lower surface) of another circuit board to be laminated (hereinafter, may be simply referred to as “protrusion portion”) is laminated. Is accommodated in the protrusion part of the recess structure provided in the land part or its adjacent part on the circuit board of the present invention,
It is electrically connected to the land portion. Therefore, it is possible to prevent the thickness in the vicinity of the land portion from increasing when the circuit boards are attached to each other. Further, since the increase in the thickness in the vicinity of the land portion is prevented, the circuit board is not pulled near the land portion. Further, it is possible to surely prevent the inconvenience that the conductive resin composition pressed against the land portion comes into contact with another land portion or a non-connection portion of the wiring portion. That is, the smoothness of the multi-layer substrate in which a plurality of circuit boards are bonded together is improved, and advantages such as improvement in electrical reliability of the connection portion can be obtained.

The "land portion or a portion adjacent to the land portion", which indicates the formation position of the protruding portion absorbing portion, will be described. In the protruding portion absorbing portion provided on the "land portion", the entire protruding portion absorbing portion of the hollow structure is the land. It is formed on the inner side of the portion, and refers to the protruding portion absorbing portion having a configuration in which the entire outer periphery is surrounded by the land portion. On the other hand, the protrusion absorbing portion provided in the “adjacent portion” is formed on the circuit board outside the land portion, and faces a part of the outer peripheral portion of the land portion on the circuit board ( (Adjacent) refers to a configuration that has a hollow structure.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a circuit board of the present invention and a multilayer board using the circuit board will be described below with reference to the drawings. In the following description, the upper side will be referred to as "upper" and the lower side will be referred to as "lower" in the drawings. The circuit boards (circuit boards according to the present invention, and circuit boards laminated on the conductor circuits of the circuit boards) in the respective embodiments described below are all base materials for forming a multilayer board. , An FPC (flexible printed circuit board) made of a single-sided copper-clad resin film. That is, the circuit board uses a resin film (hereinafter, referred to as an “insulating resin film”) made of a flexible insulating material such as polyimide or polyethylene terephthalate as a substrate and has one surface (hereinafter, also referred to as an upper surface) on the substrate. , A thin conductor such as a copper foil having a circuit pattern having a land portion formed thereon (a conductor circuit, which is made of copper foil here) is attached, and the other surface is made of thermoplastic polyimide or the like. It has a basic structure in which an adhesive layer made of is formed. The circuit pattern including the land portion can be formed by etching or the like. However, the adhesive layer is not necessary when the insulating resin film itself provided with the conductor circuit has an adhesive function.

Further, each circuit board has a conductive resin composition (hereinafter, the conductive resin composition is also referred to as a conductive paste) filled in a hole (hereinafter, also referred to as a via hole or a through hole) penetrating the entire circuit board. And a surface of the circuit board opposite to the conductor circuit (hereinafter, also referred to as a lower surface. If an adhesive layer is provided, an outer surface of the adhesive layer) is attached to one surface of the board (conductor circuit). ), A conductive paste filled in a hole (hereinafter, also referred to as an inner via hole or a non-through hole), and a circuit of the conductive paste filled in the hole (the above-mentioned through hole or non-through hole). It is configured to have a protruding portion that is a portion protruding from the lower surface of the substrate. The conductive paste can be embedded in the holes of the circuit board by screen printing or the like from the non-copper foil side (the surface on which the copper foil is not attached).

The projecting portion absorbing portion of the circuit board proposed by the present invention has a recess structure for absorbing the projecting portion of the conductive paste in the land portion or the adjacent portion thereof. Each of the circuit boards constituting the multilayer board of this embodiment is one in which the projecting portion absorbing portion is formed in advance before stacking, and the multilayer board of the embodiment stacks a plurality of such circuit boards. Formed by. The protrusion absorbing portion has an opening size larger than the maximum outer diameter of the protrusion of the conductive paste.
Therefore, it is easy to insert the protrusion into the protrusion absorbing portion when stacking the circuit boards, and it is also easy to position the protrusion so that the protrusion absorbing portion can be inserted.
On the other hand, the protruding dimension of the conductive paste on the circuit board side laminated on the conductor circuit from the circuit board is larger than the thickness of the land portion. The protrusion pressed against the bottom of the swells in the lateral direction and fills the protrusion absorbing portion. Here, the land part is
The thickness of the land, which is a part of the conductive circuit on the circuit board, is the thickness of the conductive layer forming the conductive circuit.

The protruding portion of the conductive paste is preferably sized to have a volume of about 50 to 100% with respect to the volume of the protruding portion absorbing portion. Each of the embodiments of the invention described below is performed. The volume of the protruding portion of the conductive paste shown in the above form is 50 to 100% of the volume of the protruding portion absorbing portion. The volume of the protruding portion of the conductive paste is slightly reduced by heating when thermocompression-bonded to the land portion as described later, so the volume (volume before heating in the case of thermocompression bonding) is smaller than the volume of the protruding portion absorbing portion. If it is 100% or less, the whole is absorbed by the protruding portion absorbing portion without overflowing from the protruding portion absorbing portion. As a result, it is possible to surely prevent disadvantages such as an increase in the thickness of the multilayer substrate at the connecting portion between the land portion and the protruding portion, and to obtain a smooth multilayer substrate. If the volume of the protruding portion of the conductive paste is 50% or more of the volume of the protruding portion absorbing portion, there is a problem that the electrical connection with the land portion becomes insufficient due to insufficient filling of the conductive paste in the protruding portion absorbing portion. Can be avoided.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. Figure 1
2, reference numeral 11 is a circuit board, 2 is a board (insulating resin film) of the circuit board 11, 3 is a conductor circuit formed on the upper surface 2a of the board 2, 4 is a land portion, and 5 is a protruding portion absorbing portion. , 6 are adhesive layers formed on the lower surface 2b of the substrate 2. The projecting portion absorbing portion 5 is a recess that penetrates the central portion of the land portion 4 and reaches the upper surface 2 a of the substrate 2. Further, the protrusion absorbing portion 5 has an inner diameter φ (opening size, see FIG. 2) larger than the maximum outer diameter of the protrusion 106 described below. Although the land portion 4 having a circular contour shape is illustrated in FIG. 2, the shape of the land portion is not particularly limited, and various types such as a rectangular shape can be adopted, and the shape of the protrusion absorbing portion is also the protrusion portion. There is no particular limitation on the specific shape as long as the shape and dimensions allow the insertion of 106. This is common to other embodiments described later. There is no particular limitation on the method of forming the land portion 4 having the protruding portion absorbing portion 5, and for example, it is formed collectively when forming the conductor circuit 3 by etching or the like from a thin metal material such as a copper foil or a conductor. Circuit 3
It is possible to form the land portion 4 by laser processing, etching or the like after the formation. This also applies to each embodiment described later.

On the other hand, reference numeral 101 is a circuit board which is laminated on the conductor circuit 3 of the circuit board 11, and like the circuit board 11, a substrate 102 made of an insulating resin film and a lower surface 10 thereof.
2b, and the adhesive layer 103 laminated on 2b. Further, the circuit board 101 is formed with a hole 104 opening to the lower surface 101b of the circuit board 101, and the inside of the hole 104 is filled with a conductive paste 105. The hole 104 is a through hole penetrating the circuit board 101, or the lower surface 101b of the circuit board 101, that is, the surface (lower surface) of the adhesive layer 103 to the adhesive layer 103.
And a non-through hole that penetrates through the substrate 102 and reaches a conductor circuit (not shown) attached to the upper surface of the substrate 102. In addition, the circuit board 101 has a conductive paste 105.
Has a protruding portion 106 that is a portion that protrudes downward from the lower surface 101 b of the circuit board 101.

In the figure, the holes (through holes or non-through holes) of the circuit board 11 and the protruding portion absorbing portions of the circuit board 101 are not shown. Hereinafter, similarly, in each of the embodiments described later, illustration of the holes and the protrusion absorbing portions of the circuit boards to be laminated may be omitted.

FIG. 1 (b) shows a state in which the circuit boards 11 and 101 are thermocompression bonded in a vacuum atmosphere (hereinafter, "thermocompression bonding" means thermocompression bonding in a vacuum atmosphere). Formed). That is, the circuit board 11 is configured such that the protruding portion 106 of the conductive paste 105 of the circuit board 101 is accommodated in the protruding portion absorbing portion 5 of the land portion 4 of the circuit board 11.
The circuit board 101 is arranged above the
102 are overlapped and thermocompression-bonded. As a result, the circuit board 11 and the circuit board 101 are bonded to each other via the adhesive layer 103, the projecting portion 106 is embedded in the projecting portion absorbing portion 5, and the land portion 4 and the projecting portion 106 are integrated,
A multilayer substrate in which the conductor circuit 3 and the conductive paste 105 are electrically connected to each other is configured. The protrusion 106 has a larger volume than that of the protrusion 106, and thus the protrusion 106 has a large volume.
Therefore, the smoothness of the multi-layer substrate can be secured without the disadvantage that the connection portion between the land portion 4 and the conductive paste 105 rises after the storage to increase the thickness of the multi-layer substrate. Further, the conductive paste of the protrusion 106 does not protrude from the protrusion absorbing portion 5 of the circuit board 11.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 3 (a) and 3 (b). In FIGS. 3A and 3B, the circuit board 12 is the circuit board 1 in the first embodiment in which the through holes 7 are formed as via holes. The through hole 7 penetrates the substrate 2 from the lower surface 12b of the circuit board 12, that is, the surface (lower surface) of the adhesive layer 6 here, reaches the projecting portion absorbing portion 5, and is opened. A conductive paste 8 is filled inside the through hole 7, and the conductive paste 8 has a protruding portion 8 a protruding downward from the lower surface of the circuit board 12, that is, protruding below the surface of the adhesive layer 6. There is. On the other hand, the upper end of the conductive paste 8, that is, the end opposite to the protruding portion 8a (hereinafter, also referred to as the upper end) is at a position almost reaching the protruding portion absorbing portion 5. In FIG. 3A, the upper end of the conductive paste 8 is shown flush with the substrate upper surface 2 a, but the upper end position of the conductive paste 8 is the conductive paste of the protruding portion that is accommodated and filled in the protruding portion absorbing portion 5. It suffices that they can be integrated with and electrically connected to, and may be slightly displaced upward or downward from the substrate upper surface 2a.

FIG. 3B shows a plurality of circuit boards 101, 1
2 shows a state in which the two are superposed and thermocompression-bonded (a state in which a multilayer substrate is formed). In FIG. 3B, the laminated circuit boards are bonded to each other via the adhesive layer 6. In addition, the protruding portions of the conductive paste of the circuit boards 101 and 12 are embedded in the protruding portion absorbing portion 5 of the land portion of the circuit board that is laminated thereunder, and are electrically connected to the land portions 4. This is the same as that of the first embodiment, but it is also integrated with the conductive paste 8 of the lower circuit board and electrically connected so as to be electrically conductive. As a result, a through wiring penetrating over a plurality of circuit boards is formed.

Specifically, FIG. 3B shows the circuit board 10.
The lower side of the circuit board 12 joined to the lower side of the circuit board 1 is further connected to the circuit board 12 (for convenience of description, two circuit boards 12 are denoted by different reference numerals 12-1 and 12-2 in FIG. 3B). Are joined). The joining of these circuit boards is thermocompression bonding. Between the joined circuit boards 12, the protruding portion 8a of the conductive paste 8 of the upper circuit board 12-1 is
It is embedded in the projecting portion absorbing portion 5 of the land portion 4 on the lower circuit board 12-2 and is electrically connected to the land portion 4, and further, the conductive paste 8 for the via hole of the circuit board 12-2. Both are electrically connected to each other. As a result, through wirings are formed so as to extend over three (or more) circuit boards including the circuit board 101. In addition, if the number of stacked circuit boards 12 is further increased, it is possible to form a through wiring connecting the conductive pastes 8 of the via holes of three or more circuit boards 12.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b). In FIGS. 4A and 4B, the circuit board indicated by reference numeral 13 is a recess in which the protruding portion absorbing portion 51 formed in the land portion 4 does not reach the substrate upper surface 2 a, and the protruding portion absorbing portion 51.
Is different from the circuit board 11 of the first embodiment in that it is located on the conductor (conductor thin material) forming the land portion 4. Other configurations are the same as those of the circuit board 11. In addition,
For convenience of description, in FIGS. 4A and 4B, the land portion 4 in which the protruding portion absorbing portion 51 is formed may be described with reference numeral 41.

Since the circuit board 13 has a conductor for forming the land 41 on the entire bottom of the protrusion absorbing portion 51, as shown in FIG. 4B, the circuit board 13 and this circuit board 13 are provided. When the protrusion 106 is embedded in the protrusion absorbing portion 51 of the circuit board 13 by bonding with the circuit board 101 arranged above by thermocompression bonding (a multilayer substrate is formed), the conductive paste of the protrusion 106 is formed. Can be reliably brought into contact with the conductor of the land portion 41, and the conductive paste of the via hole of the circuit board 101 and the conductor circuit 3 of the circuit board 13 can be made.
The electrical connection between the and can be reliably ensured.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIGS. 5 (a) and 5 (b). In FIGS. 5A and 5B, the circuit board 14 has a structure in which the holes 71 as inner via holes are formed in the circuit board 13 of the third embodiment. The hole 71
Is a land portion 4 that penetrates the substrate 2 from the lower surface 14b of the circuit board 14, that is, the surface (lower surface) of the adhesive layer 6 here.
1 has been reached. However, this hole 71 is
1 is a non-through hole that is not penetrated. A conductive paste 8 is filled inside the hole 7, and the conductive paste 8 has a protruding portion 8 a protruding downward from the lower surface 14 b of the circuit board, that is, protruding below the surface of the adhesive layer 6. On the other hand, the upper end of the conductive paste 8, that is, the protruding portion 8
An end portion (hereinafter, also referred to as an upper end) on the opposite side to a reaches the land portion 41 and is electrically connected to the land portion 41.

As shown in FIG. 5B, the protrusion 106 is formed in the protrusion absorbing portion 51 of the circuit board 14 by thermocompression bonding of the circuit board 14 and the circuit board 101 arranged on the circuit board 14. When embedded, the conductive paste 105 on the circuit board 101 side is electrically connected to the conductor circuit 3 on the circuit board 14 by the connection between the conductive paste of the protruding portion 106 and the land portion 41, and further, the land portion is further connected. Vias 41 are connected to the conductive paste 8 in the inner via holes of the circuit board 14 so as to be electrically conductive, and a through wiring penetrating over the plurality of circuit boards 14 and 101 is formed.

Further, in FIG. 5B, the circuit board 14 is provided below the circuit board 14 (hereinafter, for convenience of description, different reference numerals 14-1 and 14-2 are given to the two circuit boards 31 in the figure. (Sometimes described separately) may be arranged to form a multilayer substrate by thermocompression bonding. In this case, similarly to the connection between the conductive pastes 8 and 105 of the circuit boards 14 and 101, the protruding portion 8a of the conductive paste 8 on the circuit board 14-1 side is connected to the land portion of the conductor circuit 3 on the circuit board 14-2. By embedding it in the projecting portion absorbing portion 51 of 41, the conductive pastes 8 in the inner via holes 71 of the circuit boards 14-1 and 14-2 are separated from each other by the land portion 4 of the circuit board 14-2.
Since it is electrically conductively connected via 1, it is possible to form a through wiring having a shape penetrating over a larger number of circuit boards. The number of circuit boards 14 stacked is not particularly limited, and may be three or more.

(Modification) FIGS. 5A and 5B exemplify a configuration in which the entire protrusion absorbing portion 51 formed in the land portion 4 is a recess that does not reach the upper surface 2a of the substrate. However, in the present invention, it is also possible to adopt a configuration in which a part of the recess of the protrusion absorbing portion reaches the substrate upper surface 2a. Also,
The portion of the recess of the protruding portion absorbing portion that reaches the substrate upper surface 2a communicates with the hole 71 of the circuit board, and the conductive paste of the protruding portion 106 protruding on the lower surface of the circuit substrate 101 is the protruding portion absorbing portion. It is also possible to employ a configuration in which the conductive paste 8 in the hole 71 is directly contacted with the conductive paste 8 to be electrically connected when filled.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIGS. 6 (a) and 6 (b). In FIGS. 6A and 6B, the circuit board indicated by reference numeral 15 is replaced with the projecting part absorbing part 5 of the circuit board 11 of the first embodiment, and the land part 4 has a mortar-shaped projecting part absorbing part 52. Is formed. Other configurations are similar to those of the circuit board 11 of the first embodiment. In addition, the protrusion absorbing portion 52
Hereinafter, the land portion 4 in which the mark is formed may be described with reference numeral 42.

The mortar-shaped protruding portion absorbing portion 52 is a tapered hole (recess) having a shape that expands from the substrate 2 side of the land portion 42 toward the upper surface side of the land portion 42, and here, the land portion 42. There is a curved inner side surface 52a (inner surface) in which the inclination angle with respect to the substrate upper surface 2a gradually decreases from the upper surface side to the substrate upper surface 2a to become a flat surface close to the substrate upper surface 2a. It is a tapered through hole that penetrates the land portion 42 and reaches the upper surface 2a of the substrate. Further, since the inner diameter of the opening of the protruding portion absorbing portion 52 on the upper surface side of the land portion 42 is larger than the maximum outer diameter of the protruding portion 106, the insertion of the protruding portion 106 is not hindered. The curved inner surface 52a of the protruding portion absorbing portion 52 can be formed by etching the land portion 4 or the like.

As shown in FIG. 6B, the circuit board 15 and the circuit board 101 arranged on the circuit board 15 are joined by thermocompression bonding, and the protruding portion absorbing portion 52 of the circuit board 15 is joined.
When the protrusion 106 is embedded in the inside (in the state where the multilayer substrate is formed), contact between the lower end of the protrusion 106 and the inner side surface 52a of the protrusion absorption unit 52, that is, the protrusion due to the mortar shape of the protrusion absorption unit 52 The conductive paste 106 can be surely brought into contact with the land portion 42, and the circuit board 101
The electrical connection between the conductive paste 105 of the via hole and the conductor circuit 3 of the circuit board 15 can be ensured. In the case of the mortar-shaped protruding portion absorbing portion 52, the volume of the protruding portion 106 is smaller than the volume of the protruding portion absorbing portion 52 (volume before heating for thermocompression bonding, volume comparison). Or
Even if the volume of the projecting portion 106 is smaller than the volume of the projecting portion absorbing portion 52 due to a reduction in the volume of the projecting portion 106 due to heating during thermocompression bonding, the conductive paste of the projecting portion 106 and the conductor of the land portion 42 The electrical connection of can be surely secured. In addition, the volume of the protrusion 106 is equal to that of the protrusion absorber 5.
Even if the volume is smaller than the volume of 2, the adhesive layer 103 on the lower surface of the circuit board 101 enters the protruding portion absorbing portion 52 and the protruding portion absorbing portion 5 is formed by thermocompression bonding between the circuit boards.
Since 2 is filled, the circuit boards are brought into close contact by thermocompression bonding. This is common to the other embodiments.

By the way, in the present invention, "mortar shape"
The projecting portion absorbing portion may be a hole (recess) formed in a tapered shape that expands from the substrate side of the land portion to the upper surface side of the land portion. 6 (a) and 6 (b) are not limited to those having the curved inner side surface 52a, for example, FIG.
Like the projecting portion absorbing portion 53 shown in (a) and (b), since it reaches the land upper surface while inclining at a constant angle with respect to the substrate upper surface, the slanted inner surface 53a extending linearly in cross section.
In FIGS. 7 (a) and 7 (b), the land portion having the projecting portion absorbing portion 53 has the reference numeral 43, and the circuit board having the land portion 43 has the reference numeral 15A. Various structures can be adopted, such as those having an inner surface (inner side surface) having a shape having unevenness such as a step in the middle. It should be noted that the inner surface 53a of the protruding portion absorbing portion 53 of the circuit board 15A shown in FIGS. 7A and 7B, which has a shape that reaches the upper surface of the land portion 43 by inclining at a constant angle with respect to the upper surface 2a of the substrate,
For example, it can be formed by laser machining of the conductor forming the land portion 4.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described with reference to FIGS. Figure 8 ~
In FIG. 9, a circuit board indicated by reference numeral 16 replaces the protruding portion absorbing portion 5 of the circuit board 11 of the first embodiment, and absorbs the protruding portion of the recess structure on the substrate 2 adjacent to the land portion. The portion 54 is formed. Other configurations are similar to those of the circuit board 11 of the first embodiment. The land portion adjacent to the protruding portion absorbing portion 54 may be described with reference numeral 44.

In FIGS. 8 to 9, the protrusion absorbing portion 5 is provided.
4 is the land portion 44 and the land portion 44 on the substrate 2.
Insertion of the protruding portion 106 of the conductive paste 105 of the circuit board 101, which is an inner area surrounded by the dam portion 55 made of synthetic resin formed at a position adjacent to the above, and is laminated on the conductor circuit 3 of the circuit board 16. The hollow structure has a shape and size that can be accommodated. The dam portion 55 is formed in a ridge shape by etching a synthetic resin layer formed on the substrate 2, printing a synthetic resin, or the like, and both ends in the extending direction reach and are connected to the land portion 44, As shown in FIG. 9B, when the circuit boards 16 and 101 are bonded to each other by thermocompression bonding, the protruding portion 10 housed in the protruding portion absorbing portion 54.
The conductive paste 6 is prevented from leaking outside from the projecting portion absorbing portion 54. Further, when the circuit boards 16 and 101 are thermocompression-bonded and integrated with each other to form a multilayer board, the conductive paste of the protruding section 106 inserted and filled in the protruding section absorbing section 54 of the circuit board 16 is the land section 44. The conductive paste in the hole 104 of the circuit board 101 and the conductor circuit 3 of the circuit board 16 are electrically connected to each other by being brought into contact with.

In the fifth and sixth embodiments, the hole-shaped (recessed structure) protruding portion absorbing portion which penetrates the land portion and reaches the substrate is illustrated. Without being limited thereto, for example, a configuration in which the land portion is formed in a recess shape that does not reach the substrate from the top surface of the land portion, that is, a configuration in which the protruding portion absorption portion 51 of the third embodiment is formed in a mortar shape, etc. Can also be adopted. Although not shown, as a circuit board having a mortar-shaped protruding portion absorbing portion, a via hole penetrating the protruding portion absorbing portion is formed, or a land portion on the upper surface side is reached from the lower surface side of the circuit board (however, A structure in which an inner via hole is formed such as a hole not opened in the land portion, that is, absorption of the protruding portion of the circuit board illustrated in the second embodiment or the fourth embodiment (and its modification). It goes without saying that a configuration in which the part is shaped like a mortar can also be adopted.

In the above-described embodiments of the present invention, the circuit board, which is a single-sided copper clad resin film, and the multilayer board configured by laminating a plurality of the circuit boards have been described. The present invention is not limited to this, and a double-sided copper-clad resin film can also be used as the circuit board. In addition,
The circuit board according to the present invention is not necessarily limited to those having the above-mentioned holes (holes that open to the lower surface, such as through holes and non-through holes), and those that do not have such holes can also be adopted. Is. The specific shape of the recess forming the protrusion absorbing portion, the relationship between the volume of the protrusion of the conductive paste and the volume of the protrusion absorbing portion, etc. are not limited to those described above,
It goes without saying that it can be changed.

[0034]

EFFECTS OF THE INVENTION According to the present invention, a via hole (or an inner via hole) of a circuit board, which is formed by filling a via hole (or an inner via hole) with a conductive resin composition, is laminated to form a via hole of the circuit board. The protrusion of the conductive resin composition is inserted and filled in the land portion or the adjacent portion of the land portion to which the protrusion portion from the filled portion of the conductive resin composition filled in the inner via hole is electrically connected. By providing the protruding portion absorbing portion having the hollow structure described above, the smoothness of the laminated multilayer substrate is improved, and the electrical reliability of the connection portion between the land portion and the protruding portion of the conductive resin composition can be improved. Such an excellent effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention, a projecting portion absorbing section on a circuit board, and a projecting section of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

FIG. 2 is a perspective view showing a protrusion absorbing portion provided on a land portion of the present invention.

FIG. 3 is a protrusion absorption portion on a circuit board according to a second embodiment of the present invention, and a protrusion portion of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

FIG. 4 is a protrusion absorption portion on a circuit board according to a third embodiment of the present invention, and a protrusion portion of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

FIG. 5 is a protrusion absorption portion on a circuit board according to a fourth embodiment of the present invention, and a protrusion portion of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

FIG. 6 is a protrusion absorption portion on a circuit board according to a fifth embodiment of the present invention, and a protrusion portion of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

FIG. 7 is a protrusion absorption portion on a circuit board according to a sixth embodiment of the present invention, and a protrusion portion of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

FIG. 8 is a perspective view showing a protrusion absorbing portion provided on a circuit board according to a seventh embodiment of the present invention.

FIG. 9 is a protrusion absorption portion on a circuit board according to a seventh embodiment of the present invention, and a protrusion portion of a conductive paste filled in a hole of a circuit board laminated on a conductor circuit of the circuit board. 3A and 3B are cross-sectional views showing the relationship between FIG. 2A and FIG. 2A, where FIG.

[Explanation of symbols]

2 ... Insulating material substrate, 3 ... Conductor circuit, 4, 411-
44 ... Land portion, 5, 51-54 ... Projection absorbing portion,
11, 12, 12-1, 12-2, 13, 14, 14-
1, 14-2, 15, 15A, 16 ... Circuit board, 10
DESCRIPTION OF SYMBOLS 1 ... Circuit board, 104 ... Hole, 105 ... Conductive resin composition, 106 ... Projection part.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Okamoto             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Sotani Mizutani             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Shoji Ito             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Pompampani Annan             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office F-term (reference) 5E317 AA07 BB03 BB12 GG03 GG11                       GG20                 5E346 AA12 AA15 AA32 AA43 CC10                       CC32 FF18 FF22 HH33 HH40

Claims (6)

[Claims] 1. A hole (10) formed in a circuit board (101) having a conductor circuit (3) formed on one or both sides of a substrate (2) made of an insulating material and laminated on the conductor circuit.
A circuit board having land portions (4, 41 to 44) connected to a protruding portion (106) protruding from the circuit board of the conductive resin composition (105) filled in 4). Part or its adjacent part, the protruding part absorbing part (5, 51 to 5) having a hollow structure for accommodating the protruding part of the conductive resin composition.
4) is provided, the circuit board (1
1, 12, 12-1, 12-2, 13, 14, 14-
1, 14-2, 15, 15A, 16). 2. The circuit board according to claim 1, wherein the protrusion absorbing portion has an opening size larger than a maximum outer diameter of the protrusion of the conductive resin composition. 3. The circuit board according to claim 1, wherein the protruding portion absorbing portion has a volume larger than that of the protruding portion of the conductive resin composition. 4. The circuit board according to claim 1, wherein at least a part of the protrusion absorbing portion is located on a conductor forming a land portion. 5. The circuit board according to claim 1, wherein the protruding portion absorbing portion is formed in a mortar shape. 6. A multilayer board formed by stacking a plurality of circuit boards including the circuit board according to any one of claims 1 to 5.