JPH10215048A - Printed wiring board and mounting structure of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the thickness of the entire printed wiring board, wherein a sub-printed wiring board is mouthed, by forming a recess part or a hole part in the surface of a main printed wiring board, and embedding the sub- printed wiring board into the recess or hole part. SOLUTION: A sub-printed wiring-board mounting recess part 11a is provided at the specified position on the predetermined surface of a main printed wiring board 11. A sub-printed wiring board 12 is embedded flush into the recess part 11a formed in this main printed wiring board 11. Thus, the thickness of the entire printed wiring board 11, on which the sub-printed wiring board 12 is mounted, can be made small. Therefore, mounting into the narrow space in a frame can be readily performed. At the same time, it is not required to provide high error accuracy in each printed wiring board 11 and a positioning mechanism. The positioning of the sub-printed wiring board 12 can be readily performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board applied to various electronic devices such as a personal computer and a portable information device, and a mounting structure thereof.

[0002]

2. Description of the Related Art In electronic devices such as personal computers and portable information devices, hardware functions peculiar to the devices are realized by using a printed wiring board on which chip parts and other circuit elements are mounted and connected to a circuit. ing.

In this type of printed wiring board, when it is desired to arbitrarily increase or change some of the functional circuits in accordance with, for example, a model change or a function change, another small printed circuit is required in a partial area of the printed wiring board. A technique for mounting a wiring board is used.
8 and 9 show a conventional wiring board mounting technique at this time.

The mounting means shown in FIG. 8 is provided with a group of electrode pads for mounting the sub-printed wiring board 02 on one side of the main printed wiring board 01 in advance. Ball bump 03 on pad
The sub-printed wiring board 02 is mounted on the main printed-wiring board 01 by soldering the sub-printed wiring board 02 with the interposition.

In the mounting means shown in FIG. 9, connectors 04a and 04b are provided on both the main printed wiring board 01 and the sub printed wiring board 02, respectively.
The sub-printed wiring board 02 is mounted on the main printed wiring board 01 by connecting a and 04b.

By using the sub-printed wiring board mounting means as described above, a sub-printed wiring board having an arbitrary functional circuit can be selectively mounted on the main printed wiring board.

However, in the above-described conventional sub-printed wiring board mounting means, since the thickness of the entire printed wiring board in the height direction is greatly increased,
A large storage space must be ensured in the limited space inside the housing, and therefore it is often difficult to apply to equipment that requires miniaturization and thinning. Had left the problem.

Further, the mounting means for soldering and mounting the sub-printed wiring board via the ball bumps on the sub-printed wiring board mounting electrode pads on the main printed wiring board includes:
As the circuit density increases and the pitch between soldered terminals becomes narrower, the sub-printed wiring board must be positioned on the main printed wiring board with higher error accuracy, and each printed wiring board and positioning mechanism have a higher error. Since precision is required, there are inconveniences in manufacturing and cost, and there is also a problem in reliability due to a bridge between terminals and the like. Also, the mounting means using the connector involves an increase in the number of components, and therefore has a problem in terms of manufacturing and cost.

[0009]

As described above, in the conventional sub-printed wiring board mounting means, since the entire thickness of the printed wiring board is greatly increased, a large storage space is required in a limited space in the housing. A space must be ensured, and therefore, it is often difficult to apply the device to a device that is required to be reduced in size and thickness, which leaves a problem in terms of a mounting space. Furthermore, in the mounting means for soldering and mounting the sub-printed wiring board with ball bumps interposed between the sub-printed wiring board mounting electrode pads on the main printed wiring board, each printed wiring board, and a positioning mechanism, Since high error accuracy is required for each, there are inconveniences in manufacturing and cost, and there is also a problem in reliability due to a bridge between terminals and the like. Also, the mounting means using the connector involves an increase in the number of components, and therefore has a problem in terms of manufacturing and cost.

The present invention has been made in view of the above circumstances,
In the printed wiring board mounting structure in which the sub printed wiring board is mounted on the main printed wiring board, the thickness of the entire printed wiring board on which the sub printed wiring board is mounted is reduced,
An object of the present invention is to provide a printed wiring board and a mounting structure of the printed wiring board which can be easily mounted in a narrow space in a housing.

Further, the present invention provides a printed wiring board mounting structure for mounting a sub printed wiring board on a main printed wiring board, wherein the thickness of the entire printed wiring board on which the sub printed wiring board is mounted is reduced. It can be easily mounted in a narrow space in the housing, and does not require very high error accuracy for each printed wiring board and positioning mechanism, and easily mounts the sub-printed wiring board on the main printed wiring board with an inexpensive configuration. It is an object of the present invention to provide a printed wiring board and a mounting structure of the printed wiring board that can be used.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a printed wiring board mounting structure for mounting a sub-printed wiring board on a main printed wiring board, wherein a concave portion or a hole is formed in the board surface of the main printed wiring board. A structure in which a sub-printed wiring board is embedded in the concave portion or the hole. With such a structure, the thickness of the entire printed wiring board on which the sub-printed wiring board is mounted is reduced, and The sub-printed wiring board can be easily mounted in a narrow space in the body, and the sub-printed wiring board can be easily mounted on the main printed wiring board with an inexpensive configuration without requiring a very high error accuracy for each printed wiring board and positioning mechanism. Can be.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a basic configuration of a printed wiring board according to a first embodiment of the present invention.

In the drawing, reference numeral 11 denotes a main printed wiring board, and a sub printed wiring board mounting recess 11a for mounting the sub printed wiring board at a predetermined position on a surface.
Is provided.

Reference numeral 12 denotes a sub-printed wiring board embedded and mounted in the sub-printed wiring board mounting concave portion 11a formed in the main printed wiring board 11, and has, for example, a higher wiring density than the main printed wiring board 11. . Here, an example is shown in which the sub-printed wiring board 12 is embedded in the recess 11a so as to be flush with the main printed wiring board 11.

As described above, the sub-printed wiring board 12 is embedded in the sub-printed wiring board mounting recessed portion 11a of the main printed wiring board 11, and the sub-printed wiring board 12 is mounted on the main printed wiring board 11. The thickness of the entire wiring board can be reduced to approximately the same as the thickness of the main printed wiring board 11, so that it can be easily mounted in a narrow space in the housing.

FIG. 2 shows an example of circuit connection (1) between substrates (wiring boards) in the above embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. I do. Here, electrode pads 11p and 11 for circuit connection are provided at a predetermined edge portion around the sub-printed wiring board mounting concave portion 11a provided on the main printed wiring board 11 and a predetermined edge portion of the sub-printed wiring board 12, respectively.
, 12p, 12p,..., and the corresponding electrode pads 11p-12p are connected to each other by soldering 13 by soldering.

In such a circuit connecting means between the main printed wiring board 11 and the sub printed wiring board 12, the sub printed wiring board 12 is fitted into the recess 11a of the main printed wiring board 11 so that the sub printed wiring board 12 is fitted. Since the mounting position of the sub-printed wiring board 12 is determined, the positioning of the sub-printed wiring board 12 is extremely easy. A printed wiring board can be mounted.

FIG. 3 shows a circuit connection example (part 2) between substrates (wiring boards) in the above embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. I do. Here, electrode pads 11p, 11p,..., 12p, 12p for circuit connection are respectively provided on the bottom surface of the concave portion 11a for mounting the sub-printed wiring board of the main printed wiring board 11 and the front surface in the embedding direction of the sub-printed wiring board 12.
Are provided, and the corresponding electrode pads 11p to 12p are connected to each other by welding with solder 13 or bonding with a conductive adhesive. In this case, as the solder welding means, reflow soldering for heating from the bottom surface of the recessed portion of the main printed wiring board 11 or reflow soldering for blowing hot air into a gap formed between the wiring boards in the recessed portion 11a for heating. And any other welding means.

In such a circuit connecting means between the main printed wiring board 11 and the sub printed wiring board 12, the sub printed wiring board 12 is fitted into the concave portion 11a of the main printed wiring board 11 so that the sub printed wiring board 12 is fitted. Since the mounting position of the sub-printed wiring board 12 is determined, the positioning of the sub-printed wiring board 12 is extremely easy. A printed wiring board can be mounted. Further, in this case, since the circuit connection portion between the main printed wiring board 11 and the sub-printed wiring board 12 is accommodated in the recess 11a, the board surface of the main printed wiring board 11 can be further flattened. Can be integrated by sealing the void portion with resin.

FIG. 4 shows a circuit connection example (part 3) between substrates (wiring boards) in the above embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. I do. Here, between the main printed wiring board 11 and the sub printed wiring board 12, at the bottom surface of the sub printed wiring board mounting concave portion 11a of the main printed wiring board 11, an inner copper foil 11s exposed on the bottom surface, Wiring board 12
A circuit connection such as a ground connection is made by the through hole 12t provided in the main printed wiring board 11, and the electrode pad 11 of the main printed wiring board 11 is formed on the surface pattern surface.
, and the electrode pads 12p, 12p,... of the sub-printed wiring board 12 are connected to each other via a solder 13 or a circuit component 14, such as a chip component. In the figure,
B is an adhesive for resin sealing.

In such a circuit connecting means between the main printed wiring board 11 and the sub printed wiring board 12, the sub printed wiring board 12 is fitted into the concave portion 11a of the main printed wiring board 11 so that the sub printed wiring board 12 is fitted. Since the mounting position of the sub-printed wiring board 12 is determined, the positioning of the sub-printed wiring board 12 is extremely easy. Therefore, each printed wiring board and the positioning mechanism do not require high error accuracy and can be easily mounted on the main printed wiring board with an inexpensive configuration. A printed wiring board can be mounted. Further, in this case, since the circuit connection portion between the main printed wiring board 11 and the sub-printed wiring board 12 can be made both in the concave portion 11a and in the surface layer pattern surface, for example, the through hole 1 is formed in the concave portion 11a.
With 2t, a current circuit such as a ground (GND) and a Vcc power supply can be easily formed, and the gap between electrode pads, the number of wirings, etc. can be easily increased.

FIG. 5 shows an application example of the above embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Here, the circuit component 14 mounted on the sub-printed wiring board 12 is connected to the inner layer copper foil 11s exposed on the bottom surface of the sub-printed wiring board mounting concave portion 11a provided on the main printed wiring board 11, and Part 14
The heat generated due to the internal loss generated in step (1) is radiated through the inner copper foil 11s.

Thus, for example, when a circuit element such as a CPU chip that generates heat due to internal loss during operation is mounted on the sub-printed wiring board 12, the heat generated by the circuit element is transferred to the inner layer copper of the main printed wiring board 11. Heat can be efficiently radiated through the foil 11s. In the figure, B is an adhesive for sealing the resin.

FIG. 6 is a side sectional view showing a basic structure of a printed wiring board according to a second embodiment of the present invention. In the figure, 2
Reference numeral 1 denotes a main printed wiring board, in which a hole 21a for mounting a sub printed wiring board is formed on a predetermined board surface. Reference numeral 22 denotes a sub-printed wiring board which is embedded in a hole 21 a for mounting the sub-printed wiring board formed on the main printed wiring board 21 and mounted on the main printed wiring board 21. Consists of density. Here, the holes 2 are formed such that the sub-printed wiring board 22 is flush with the main printed wiring board 21.
The example embedded in 1a is shown.

As described above, the sub-printed wiring board 22 is embedded in the sub-printed wiring board mounting hole 21 a of the main printed wiring board 21, and the sub-printed wiring board 22 is mounted on the main printed wiring board 21. ,
The thickness of the entire printed wiring board is determined by the main printed wiring board 21.
The thickness can be reduced to approximately the same as the thickness of the housing, and it can be easily mounted in a narrow space in the housing.

Incidentally, the circuit connection between the substrates (wiring boards) at this time can be easily realized by using, for example, the circuit connecting means as shown in FIG. Also in this case, the main printed wiring board 2
Since the mounting position of the sub-printed wiring board 22 is determined by fitting the sub-printed wiring board 22 into the one hole 21a, the positioning of the sub-printed wiring board 22 is extremely easy. The sub-printed wiring board can be easily mounted on the main printed wiring board with an inexpensive configuration without requiring high error accuracy.

FIG. 7 is a side sectional view showing a modification of the printed wiring board according to the second embodiment. In this example, a step is formed in the hole 21a of the main printed wiring board 21, the opening of the plate surface in the front of the sub-printed wiring board 22 in the fitting direction is narrowed, and formed at the opening edge of the hole 21a. The electrode pads 21p, 2p corresponding to the electrode pads 22p, 22p,.
Are provided, and the corresponding electrode pads 21p-2 are provided.
The circuits 2p are connected to each other by reflow soldering or a conductive adhesive as described above.

Even in such a configuration, the mounting position of the sub-printed wiring board 22 is determined by fitting the sub-printed wiring board 22 into the hole 21a provided in the main printed wiring board 21, so that the sub-printed wiring board 22 is fixed. The positioning of the printed wiring board 22 is extremely easy. Therefore, the sub-printed wiring board can be easily mounted on the main printed wiring board with an inexpensive configuration without requiring high error accuracy for each printed wiring board and positioning mechanism.

In each of the above-described embodiments, an example is shown in which one sub-printed wiring board is embedded and mounted in one main printed wiring board. A configuration in which one or a plurality of sub-printed wiring boards are embedded and mounted, or a recess and a hole for mounting a sub-printed wiring board are separately provided in one main printed wiring board, and the recesses and the holes are provided. The mounting structure may be a combination of various combinations, such as a configuration in which a sub-printed wiring board is embedded and mounted in each.
Also, for circuit connection between substrates (wiring boards), various circuit connection means such as a combination of the above-described circuit connection examples or a circuit connection using, for example, a side wall of a concave portion for mounting a sub-printed wiring board can be applied. It is.

[0031]

As described above in detail, according to the present invention, in a printed wiring board mounting structure in which a sub-printed wiring board is mounted on a main printed wiring board, a recess is formed on the board surface of the main printed wiring board. And, by adopting a printed wiring board mounting structure in which the sub printed wiring board is embedded in the concave portion, the thickness of the entire printed wiring board on which the sub printed wiring board is mounted is reduced, and the printed wiring board is mounted in a narrow space in the housing. The sub-printed wiring board can be easily mounted on the main printed wiring board with an inexpensive configuration without requiring a very high error accuracy for each printed wiring board and the positioning mechanism.

According to the present invention, in a printed wiring board mounting structure for mounting a sub-printed wiring board on a main printed wiring board, a hole is formed in a board surface of the main printed wiring board, and the hole is formed. The printed wiring board mounting structure with the sub-printed wiring board embedded in it reduces the thickness of the entire printed wiring board on which the sub-printed wiring board is mounted, making it easy to mount in a narrow space inside the housing. The sub-printed wiring board can be easily mounted on the main printed wiring board with an inexpensive configuration without requiring a very high error accuracy for each printed wiring board and positioning mechanism.

Further, according to the present invention, in a printed wiring board having a sub-printed wiring board mounted on a main printed wiring board, a concave portion formed in a partial surface area of the main printed wiring board; A sub-printed wiring board that is at least partially embedded and mounted on the main printed wiring board, thereby reducing the thickness of the entire printed wiring board and reducing the space inside the housing. The sub-printed wiring board can be easily mounted on the main printed wiring board with an inexpensive configuration without requiring a very high error accuracy for each printed wiring board and positioning mechanism.

Further, according to the present invention, in a printed wiring board in which a sub printed wiring board is mounted on a main printed wiring board, the main printed wiring board is formed in a partial area of the main printed wiring board. And a sub-printed wiring board at least partially embedded in the hole and mounted on the main printed wiring board, thereby reducing the thickness of the entire printed wiring board. It can be easily mounted in a narrow space inside the housing, and does not require very high error accuracy for each printed wiring board and positioning mechanism. Board can be mounted.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a basic configuration of a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing a circuit connection example (part 1) between substrates (wiring boards) in the embodiment.

FIG. 3 is a side sectional view showing a circuit connection example (part 2) between substrates (wiring boards) in the embodiment.

FIG. 4 is a side sectional view showing a circuit connection example (part 3) between substrates (wiring boards) in the embodiment.

FIG. 5 is a side sectional view showing an application example of the embodiment.

FIG. 6 is a side sectional view showing a basic configuration of a printed wiring board according to a second embodiment of the present invention.

FIG. 7 is a side sectional view showing a modified example of the printed wiring board in the second embodiment.

FIG. 8 is a side sectional view showing the structure of a printed wiring board using a conventional wiring board mounting technique.

FIG. 9 is a side sectional view showing the structure of a printed wiring board using a conventional wiring board mounting technique.

[Explanation of symbols]

 11: Main printed wiring board, 11a: Sub-print wiring board mounting recess, 11p: Electrode pad, 11s: Inner layer copper foil, 12: Sub-printed wiring board, 12p: Electrode pad, 12t: Through hole, 13: Solder, 14 ... Circuit components, 21 ... Main printed wiring board, 21a ... Sub printed wiring board mounting hole, 21p ... Electrode pad, 22 ... Sub printed wiring board, 22p ... Electrode pad, B ... Adhesive.

Claims (9)

[Claims] 1. A printed wiring board mounting structure in which a recess is formed in a board surface of a main printed wiring board and a sub printed wiring board is embedded in the recess. 2. A printed wiring board mounting structure in which a hole is formed in a board surface of a main printed wiring board, and a sub printed wiring board is embedded in the hole. 3. The printed wiring board mounting structure according to claim 1, wherein the main printed wiring board and the sub printed wiring board have different wiring densities. 4. The printed wiring board mounting structure according to claim 1, wherein the wiring density of the sub printed wiring board is higher than the wiring density of the main printed wiring board. 5. A main printed wiring board, a recess formed in a partial surface area of the main printed wiring board, and a subprint mounted on the main printed wiring board at least partially embedded in the recess. A printed wiring board, comprising: a wiring board. 6. A main printed wiring board, a hole formed in a partial surface area of the main printed wiring board, and at least a part embedded in the hole and mounted on the main printed wiring board. A printed wiring board, comprising: a sub-printed wiring board. 7. The printed circuit according to claim 5, wherein an electrode pad is provided on at least one side or one side of the sub-printed wiring board, and the sub-printed wiring board is connected to the main printed wiring board by the electrode pads. Wiring board. 8. A predetermined circuit connection is made between the sub printed wiring board and the main printed wiring board by connecting an inner layer circuit pattern of the main printed wiring board to a through hole of the sub printed wiring board. Or 6 or 7
The printed wiring board as described. 9. The printed wiring board according to claim 5, wherein a chip component is mounted on at least one surface of the sub-printed wiring board in advance.