JPH0669655A - Circuit board and its manufacture - Google Patents

Abstract

PURPOSE:To provide a circuit board on which high-density mounting can be performed and soldering can be performed in a stable state by using a reflow furnace. CONSTITUTION:The title circuit board is composed of a multilayered substrate formed by joining a plurality of substrates to each other and constituted to high-density mounting in such a way that blind through holes 14 are formed through substrates 11 and 13 on the external surface at the parts of connection lands 25 so as to connect the lands 25 to a wiring pattern 26 on the other surface. At the same time, excellent soldering can be performed on the circuit board with a reflow furnace by respectively forming the holes 14 or dummy blind through holes 27 at the connection lands 25 connected to electrodes 24 at both ends of parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board and a method for manufacturing the same, and in particular, a circuit part is mounted on the circuit board and electrically connected through a wiring pattern to form a predetermined circuit. The present invention relates to a circuit board and a manufacturing method thereof.

[0002]

2. Description of the Related Art Circuit boards having wiring patterns are widely used to form various electronic circuits. A wiring pattern is formed on a circuit board made of an insulating material, and connection lands to be connected to electrodes of circuit components are formed. Therefore, a predetermined electronic circuit is formed by mounting the circuit component on the surface of the circuit board so that the electrode is connected to such a connection land.

[0003]

With the miniaturization of electronic equipment, high-density mounting is required to densely mount a large number of components on a circuit board. In an electronic circuit that requires high-density mounting, a multilayer board is used to improve the density of the circuit board.

For high-density mounting, not only the surface area of the wiring must be reduced, but also the area occupied by the through holes must be reduced. However, there is a limit to reducing the diameter of the through hole, and the area of the through hole hinders high-density mounting. That is, there is a limit to high-density mounting simply by forming a multilayer board.

The present invention has been made in view of the above problems, and in particular, the area occupied by the through holes is reduced as much as possible in the case where the substrate is made to have a multi-layer structure, thereby enabling higher density mounting. An object of the present invention is to provide a circuit board and a manufacturing method thereof.

[0006]

According to a first aspect of the present invention, a circuit board is mounted on which a circuit component is mounted and electrically connected through a wiring pattern to form a predetermined circuit. The circuit component is mounted on the surface of the circuit board so that the electrode of the circuit component is connected to the connection land on the surface, and a blind through hole is formed in the connection land. The present invention relates to a circuit board, wherein the connection land is connected to a wiring pattern on the other surface of the circuit board.

A second invention is the same as the first invention,
The present invention relates to a circuit board characterized in that a dummy blind through hole is formed in a connection land that is not connected to a wiring pattern on the other surface of the connection land on the outer surface of the circuit board.

A third aspect of the present invention is a method for manufacturing a circuit board, which is formed by joining a plurality of boards having wiring patterns,
A through hole is formed in the substrate arranged so as to face the outer surface, the inner peripheral surface of the through hole is plated, and then the through hole is filled with resin to form a blind through hole. The substrates are joined, a through hole is formed so as to penetrate through the plurality of joined substrates, the inner peripheral surface of the through hole is plated, and the blind through hole filled with the resin at this time is formed. The present invention relates to a method for manufacturing a circuit board, characterized in that the surface is plated.

[0009]

According to the first aspect of the invention, the blind through hole is formed in the connecting land to which the electrode of the circuit component is connected, and the blind through hole connects the connecting land to the wiring pattern on the other surface of the circuit board. It is supposed to be done. Therefore, the space for providing the blind through hole can be obtained for the connection land,
There is no waste of space due to the independent formation of blind through holes.

According to the second invention, dummy blind through holes are formed in the connection lands that are not connected to the wiring pattern on the other surface, and the dummy blind through holes provide the non-dummy blind through holes. By making the connection lands and thermal capacities approximately the same, the tombstone phenomenon (part standing) during reflow soldering can be suppressed.

According to the third aspect of the invention, the blind through hole is filled with resin after the inner peripheral surface of the blind through hole is plated, and the blind through hole is formed on the inner peripheral surface of the through hole that penetrates the plurality of bonded substrates. When plating is performed, the surface of the blind through hole filled with the resin is plated, and this plating constitutes at least a part of the connection land.

[0012]

1 and 2 show an initial process for manufacturing a circuit board according to an embodiment of the present invention.
That is, the circuit board according to this embodiment includes three boards 11,
Use 12 and 13. Blind through holes 14 are formed in advance on the upper substrate 11 and the lower substrate 13, respectively. Blind through hole 1
Reference numeral 4 is a through hole formed in these substrates 11 and 13, and as shown in FIG. . Then, these blind through holes 14 are filled with the resin 15 after the plating 15 is applied.

If the blind through holes 14 are formed on the upper and lower substrates 11 and 13 in this manner, respectively,
As shown in FIGS. 3 and 4, the three substrates 11 to 13 are
The adhesive layers 19 are bonded to each other to form a five-layer structure including the adhesive layer 19. Then, the through holes 20 are formed in the joined state as shown in FIG. Through hole 2
0 is formed so as to penetrate the three substrates 11 to 13 and the adhesive layer 19 interposed therebetween. Then, plating 21 is applied to the inner peripheral surface of the through hole 20, so that the upper and lower surfaces of the substrates 11, 12, and 13 are electrically connected. Moreover, when the plating 21 is applied to the inner peripheral surface of the through hole 20, the blind through hole 1 is filled with the resin 16 on the outer surfaces of the upper and lower substrates 11 and 13.
Plating 21 is also applied to the outer surface of 4.

6 and 7 show the connection state of the circuit board thus formed. 6 and 7
Is a wiring pattern formed on the upper and lower surfaces of the three substrates 11, 12, and 13 for convenience sake, and the first layer 31 and the second layer 32 are the upper and lower surfaces of the substrate 11. It is a wiring pattern formed in. The third layer 33
And the fourth layer 34 are wiring patterns formed on the upper and lower surfaces of the intermediate substrate 12. The fifth layer 35 and the sixth layer 36 are wiring patterns formed on the upper and lower surfaces of the lower substrate 13, respectively.

The wiring patterns of these 6 layers are connected to each other by the plating 21 of the through holes 20. Moreover, the first layer 31 and the second layer 32 are connected by the plating 15 of the blind through hole 14. Further, the fifth layer 35 and the sixth layer 36 are connected by the plating 15 of the blind through hole 14. A dummy blind through hole 27 may be formed between the first layer and the second layer or between the fifth layer and the sixth layer, if necessary.

FIGS. 8 and 9 show a state in which the circuit component 23 is mounted on such a multilayer circuit board. The electrodes 24 at both ends of the circuit component 23 are provided on the upper surface. The connection lands 25 are connected to each other. Moreover, as shown in FIGS. 8 and 9, a blind through hole 14 is formed substantially in the center of the connecting land 25, and the blind through hole 14 is connected to the wiring pattern 26 on the lower surface of the substrate 11. Has become. 8 and 9, the connection land 25 on the right side is the through hole 20.
The dummy blind through hole 27 is formed below the connection land 25 because it is connected to the plating 21.

FIG. 10 shows another example of mounting the circuit component 23. In this example, the electrodes 24 at both ends of the circuit component 23 are both connected to the connecting lands 25, and blind through holes 14 are formed below the connecting lands 25, respectively. The hole 14 is connected to the wiring pattern 26 formed on the lower surface of the substrate 11. The wiring pattern 26 corresponds to the second layer 32 in FIGS. 6 and 7.

As shown in FIGS. 6 and 7, in a substrate having a six-layer wiring pattern, the first layer 31 and the sixth layer 36 form the component mounting surface. The second layer 32 and the fifth layer 35 connected to the first layer and the sixth layer by the blind through hole 14 and the through hole 20 form a wiring layer. On the other hand, the intermediate third
The layer 33 and the fourth layer 34 are configured as a power supply GND layer.

For example, the blind through hole 1 is provided between the first layer 31 and the second layer without using the usual through hole 20.
4 allows connection to be made, so that the blind through hole 14 is formed on the lower sixth layer 36.
It becomes possible to freely mount a completely different component directly under the position.

The method of manufacturing the circuit board in which the blind through hole 14 and the normal through hole 20 are mixed as described above has the first layer 31 and the second layer 32 as described above.
Further, the substrate 11 having the blind through hole 14 and the substrate 12 having the third layer 33 and the fourth layer 34
And the substrate 13 having the fifth layer 35 and the sixth layer 36 and provided with the blind through holes 14 are prepared in advance as shown in FIGS. 1 and 2, respectively.
And by making a hole as shown in FIG. 4 and forming a through hole 20 as shown in FIG. The through holes 20 are the substrates 11 and 1 joined together.
A vertical hole is made in the circuit board consisting of 2 and 13. On the other hand, for the blind through hole 14, it is also possible to form the through hole by bonding the three substrates 11 to 13 and then forming a hole corresponding to the depth and plating. The former method is described in the above embodiment.

When the former method is used, the first layer 31
The inner surface of the blind through hole 14 formed on the substrate 11 having the second layer 32 and the substrate 13 having the fifth layer 35 and the sixth layer 36 is plated in advance with 1
5 is applied, and moreover, it is filled with the resin 16 so as to be filled. Then, after that, the three substrates 11 and 13 are joined to form a through hole 20 penetrating as a multilayer structure, and plating 21 is applied to the inner surface thereof. At this time, at the same time, the resin 16
Plating 21 is also applied to the portion covered with. Then, the blind through hole 1 with this plating 21
The outer surface of 4 is used as at least a part of the connection land 25 for mounting the circuit component 23.

According to such a circuit board, the blind through hole 14 is provided inside the connection land 25, whereby the blind through hole 1 is formed.
No special space is needed to provide 4. That is, the blind through holes 14 can be formed in the mount land 25 of the component 23 without taking up space, and higher density mounting is possible.

Further, when the size of the circuit component 23 connected by the connecting land 25 becomes small, when the thermal capacity of the connecting land 25 is different at the time of soldering by the reflow furnace, the melting time of the solder is different, which is preferable. This can cause a tombstone phenomenon that causes parts to stand up and a top plastic that cannot be soldered properly. Therefore, in particular, as shown in FIG. 10, the blind through holes 14 are provided in the connecting lands 25 on both sides. When the blind through hole 14 on one side is unnecessary, a dummy blind through hole 27 is formed as shown in FIG. This allows good soldering with a reflow oven.

As described above, the circuit board according to the present embodiment relates to the circuit board in which the blind through hole 14 for connecting only a specific layer is provided together with the through hole 20 which normally penetrates. The blind through hole 14 for connecting between the layer 31 and the second layer 32 or between the fifth layer 35 and the sixth layer 36 is provided on the connecting land 25 of the circuit component 23 for surface mounting. is there. Further, the blind through holes 14 in the connection land 25 are always provided on both sides of the circuit component 23 so that the heat capacities are the same.

According to this structure, by using the blind through hole 14, it is possible to provide a circuit board capable of extremely high-density mounting close to the ultimate mounting whose surface area is almost equal to the surface area of the component. become.
Further, by providing the blind through holes 14 on the connecting lands 25 on both sides without fail or by providing the dummy blind through holes 27, it becomes possible to improve the solderability by the reflow furnace.

[0026]

According to the first aspect of the present invention, blind through holes are formed in the connecting lands, and the connecting lands are connected to the wiring pattern on the other surface of the circuit board by the blind through holes. Therefore, a special space for providing a through hole for connecting to the wiring pattern on the other surface is not required, and a circuit board capable of high-density mounting can be provided.

A second invention is such that a dummy blind through hole is formed in a connection land which is not connected to a wiring pattern on another surface. Therefore, such a dummy blind through hole can have the same heat capacity as that of the connection land having the normal blind through hole, and the solderability by the reflow furnace can be improved.

According to a third aspect of the present invention, a through hole is formed in a substrate arranged so as to face the outer surface, the inner peripheral surface of the through hole is plated, and then the through hole is filled with resin to perform blind through. After forming a hole, a plurality of boards are joined together, a through hole is formed so as to penetrate the plurality of joined boards, and the inner peripheral surface of the through hole is plated. The surface of the filled blind through hole is plated.

According to such a method, it is possible to provide a circuit board having blind through holes and normal through holes, and it becomes possible to perform high-density mounting by using such a circuit board.

[Brief description of drawings]

FIG. 1 is an external perspective view showing a plurality of substrates before bonding.

FIG. 2 is a vertical sectional view of the plurality of substrates.

FIG. 3 is an external perspective view of a state in which a plurality of substrates are joined together.

FIG. 4 is a vertical sectional view of the same.

FIG. 5 is a vertical sectional view showing a state where a through hole is formed.

FIG. 6 is a perspective view showing a state in which a wiring pattern of the joined circuit boards is shown by a surface.

FIG. 7 is a vertical sectional view of the same.

FIG. 8 is a vertical cross-sectional view of a circuit board on which circuit components are mounted.

FIG. 9 is a plan view of the same.

FIG. 10 is a vertical cross-sectional view of a circuit board on which another circuit component is mounted.

[Explanation of symbols]

 11-13 Substrate 14 Blind Through Hole 15 Plating 16 Filling Resin 19 Adhesive Layer 20 Through Hole 21 Plating 23 Circuit Component 24 Electrode 25 Connection Land 26 Wiring Pattern 27 Dummy Blind Through Hole 31 First Layer 32 Second Layer 33 Third 3rd layer 34 4th layer 35 5th layer 36 6th layer

Claims (3)

[Claims] 1. A circuit board, on which a predetermined circuit is formed by mounting a circuit component thereon and electrically connecting the circuit component through a wiring pattern, wherein the circuit component is mounted on a connection land on an outer surface. The circuit component is mounted on the surface of the circuit board so that electrodes are connected, and a blind through hole is formed in the connection land, and the wiring pattern on the other surface of the circuit board is formed by the blind through hole. A circuit board, wherein the connection land is connected to. 2. A dummy blind through hole is formed in a connection land that is not connected to a wiring pattern on the other surface of the connection land on the outer surface of the circuit board. The described circuit board. 3. A method for manufacturing a circuit board, which comprises bonding a plurality of boards each having a wiring pattern, wherein a through hole is formed in a board arranged so as to face an outer surface, and an inner peripheral surface of the through hole is formed. After plating, the through hole is filled with resin to form a blind through hole, the plurality of boards are joined, and a through hole is formed so as to penetrate the plurality of joined boards. A method of manufacturing a circuit board, wherein the inner peripheral surface of the hole is plated, and at the same time, the surface of the blind through hole filled with the resin is plated.