JPH07302963A - Printed-wiring board for surface mounting - Google Patents

Abstract

PURPOSE:To obtain a printed-wiring board which can be utilized effectively when pads for a surface mounting component are wired on the board by a method wherein a conductor circuit is formed in an unused terminal part for the surface mounting component and an insulating layer is interposed between the conductor circuit and the unused terminal. CONSTITUTION:In a printed-wiring board 10, a pad 11 is not formed in a part with which an unused terminal 22 for a surface mounting component 20 on the board is faced, and, instead, a conductor circuit 12 which is not the pad 11 on which the surface mounting component 20 is mounted is formed on the printed-wiring board 10. Then, after the conductor circuit 12 has been formed, an insulating layer 13 is formed, and the conductor circuit 12 is covered with the insulating layer 13 so as to be insulated. Thereby, the printed-wiring board which can be utilized effectively when pads 11 for the surface mounting component 20 on the board are wired and whose wiring efficiency can be enhanced is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a printed wiring board,
In particular, the present invention relates to a surface mounting printed wiring board having pads for mounting surface mounting components.

[0002]

2. Description of the Related Art Generally, electronic parts such as surface mount parts have many terminals for mounting them on a board, but these terminals are not used for various reasons. Things exist. For example, a terminal that is normally formed on a surface mount component and is called non-connection (hereinafter, simply referred to as NC terminal (22) or unused terminal (22)) has a role as a normal terminal. Without it, it is not used anywhere in the circuit design. As shown in FIG. 5, there are several NC terminals (22) in a normal surface mount component currently used. Further, in the surface mount component, there is a terminal which is not used in the circuit design although it has a role as a so-called terminal. For example, it is a terminal of a surface mount component for a gate.

On the other hand, on the printed wiring board side on which such surface mount components are mounted, pads for mounting the surface mount components have been formed corresponding to each terminal of the surface mount components. That is, among the pads formed on the printed wiring board, the pads corresponding to the NC terminals (22) of the above-mentioned surface mount component are not actually used, but
As shown in FIG. 4, on the conventional printed wiring board (30), all pads (31) (32) are formed orderly corresponding to the terminals (21) (22) of the surface mount component (20). -ing In FIG. 4 illustrated here, the pads (31) and (32) and the wiring (34) shown by solid lines are located on the front surface side of the substrate,
The wiring (34) shown by the broken line is located on the back side of the substrate.

As shown in FIG. 4, the pads (31) (32)
When the wiring pattern (34) is arranged in an orderly manner, the wiring (34) coming out of the pad (31) will be a through hole () when the wiring surrounded by the pads (31) and (32) is used. 33) and the back surface through the wiring, and the wiring (3
4) will have to be routed to the outside in a detoured state. In addition, the wiring (34) that only passes through the inside surrounded by the pads (31) (32) cannot pass through the pads (31) (32) on the surface of the substrate, so that the through hole ( 33) must be formed and wired on the back surface of the substrate, so in the printed wiring board (30), the inefficient wiring pattern (34) as shown in FIG. That is, the wiring pattern has a major obstacle in realizing the above.

Moreover, the unused pad (3
The existence of 2) runs counter to the recent increase in the number of surface mount components (20) that should be mounted on a printed wiring board (flow of double-sided mounting) and the trend of shrinking the board on which components are mounted. The existence of such an unused pad (32) makes it extremely difficult to route the wiring (34) on the substrate.
If the above-mentioned high-density mounting is attempted while allowing the existence of such unused pads (32), the cost of enlarging the outer shape of the board and increasing the number of layers of the board will also occur. Of.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the problem to be solved is to improve the wiring efficiency of a printed wiring board mounting a surface mount component (20). The cost is high due to the badness, the enlargement of the board outline and the increase in the number of layers.

The object of the present invention is to eliminate the above-mentioned problems of the prior art by not forming pads corresponding to unused terminals of the surface mount component (20) on the substrate. A conductor circuit is positively formed in a part, and an insulating layer is interposed between the conductor circuit and the unused terminals to effectively use the wiring between the pads for the surface mount component (20) of the board. It is an object of the present invention to provide a surface-mounting printed wiring board capable of ensuring high reliability of the board by improving wiring efficiency, reducing the board size accordingly, non-multilayering, and reducing through holes.

[0008]

Means adopted by the present invention to solve the above problems will be described with reference to FIGS. 1 to 3 corresponding to the embodiments. A surface mount printed wiring board having a pad row in which pads (11) connected to terminals are aligned and a surface mount component (20) mounting portion (a space (R) in the figure) surrounded by the pad row. Wiring from the outside of the surface mount component (20) mounting portion to the inside of the surface mount component (20) mounting portion through a portion corresponding to the unused terminal (22) of the surface mount component (20) of the one pad row, The surface mount component (20) through the portion corresponding to the unused terminal (22) of the surface mount component (20) of the other pad row.
While being wired to the outside of the mounting portion, at least a portion of the surface mount component (20) corresponding to the unused terminal (22) has a conductor circuit (12) covered with an insulating layer (13). Printed wiring board (10) ".

That is, in this printed wiring board (10), the pad (11) is not formed at a portion of the board where the unused terminals (22) of the surface mount component (20) face each other. Instead of the pad (11) for mounting the surface mount component (20), a conductive circuit (12) is positively formed on the substrate of the printed wiring board (10), so that each pad (11) It enables the effective use of the space (R) surrounded by. Of course, this surface mount component (2
It is not necessary to cover the part of the conductor circuit (12) other than the pad (11) for mounting (0) with the insulating layer (13) so as not to make electrical contact with other parts. is there.

[0010]

The present invention has the following actions by adopting the above means. Printed wiring board according to the present invention
In case of (10), surface mount components on the board (20)
Since the pad (11) is not formed in the portion where the unused terminals (22) of the (12) face each other, it is natural that an alternative to this portion, that is, the conductor circuit (12) required in the present invention. ) Can be formed, and three conductor circuits (12) are actually formed.

Thus, the printed wiring board according to the present invention
In (10), the space surrounded by each pad (11)
It is possible to route each conductor circuit (12) using the inside of (R), and the conventional printed wiring board (30) shown in FIG. 4 is used.
As described above, it is not necessary to form each wiring through the through hole (33).

Then, the conductor circuit (12) is a conductor circuit (12) connected to the pad (11) for the surface mount component (20) on the printed wiring board (10), and the surface mount component (20) ) Through-holes are provided because they extend inward from the mounting part (“space (R)” in the figure), pass through, and are wired to the outside of the mounting part of the surface mount component (20). Wiring can be performed without newly providing and without making a detour, and high density and low cost can be achieved.

Further, in this manner, the conductor circuit (1) is provided on the portion of the substrate where the unused terminals (22) of the surface mount component (20) face each other.
Since 2) is formed and then the insulating layer (13) is formed thereon, each conductor circuit (12) formed in the relevant portion has another portion, for example, the surface mount component (20). Even if the unused terminals (22) and the like are placed, it does not cause any problem. The present invention will now be described in detail according to the specific embodiments shown and shown in the drawings.

[0014]

First, in order to understand the present invention, the structure of a conventional printed wiring board (30) will be described with reference to FIG. In FIG. 4, the shaded pads are unused pads (32) corresponding to unused terminals (22) of the surface mount component (20). Due to the presence of the unused pad (32), in this printed wiring board (30), a certain pad (31) is located on the front surface side of the board and in the space (R) surrounded by each pad (31). The wired conductor circuit (34) cannot be easily routed.

That is, when the conductor circuit (34) wired in the space (R) is to be taken out of the space (R), it cannot interfere with each pad (31). , It is something that must be routed by using the through hole (33). Also, if you try to wire from outside the space (R) through the space (R) to the outside of the space (R) again, if you try to wire on the surface side of the board,
Since it is necessary to pass over two of the pads (31) or the unused pads (32), it is necessary to form two or more through holes (33) in order to avoid this.

On the other hand, the printed wiring board according to the present invention
In (10), it is as follows. That is, as shown in FIGS. 1 and 2, pads are not formed at the portions corresponding to the unused terminals (22) in the surface mount component (20) of the printed wiring board (10). Instead, the conductor circuit (12) is positively formed in the portion where the pad is not formed, and the insulating layer (13) is formed on the surface thereof. In the printed wiring board (10) shown in FIG. 1,
For comparison, a conductor circuit (12) was formed at a position corresponding to each conductor circuit (34) formed on the conventional printed wiring board (30).

In the printed wiring board (10) according to the present invention, the conductor circuit (12) connected to each pad (11) passes through the space (R) as it is, and from this space (R) The printed wiring board (10) is pulled out to the outside through the surface of the substrate as it is. Further, the conductor circuit (12) coming from the outside of the space (R) enters the space (R) through the part where the pad is not formed, and another pad is formed again from this space (R). It goes out from inside the space (R) through the unopened part. Therefore, the through holes (33) required in the conventional printed wiring board (30) are not required in the printed wiring board (10) at all.

Further, as shown in FIG. 3, an insulating layer (13) is formed on each portion of the printed wiring board (10) where no pad is formed, after each conductor circuit (12) is formed. The insulating layer (13) covers and insulates each conductor circuit (12) in the relevant portion. That is, an insulating layer (usually a solder resist is often used) on the part corresponding to each pad (11).
Is not formed, and the insulating layer (13) which is a solder resist is formed on the upper portion of each conductor circuit (12) shown in FIG. This allows each conductor circuit (12) and surface mount component (20)
This prevents electrical contact with the unused terminal (22), that is, short circuit. The part surrounded by the dotted line in FIG. 2 shows the insulating layer (13), that is, the part where the solder resist is not applied.

[0019]

As described in detail above, in the printed wiring board (10) according to the present invention, as illustrated in the above embodiment, "the pad (which is connected to the terminal of the surface mount component (20) ( 11)
A surface mounting printed wiring board having a pad row in which are aligned and a surface mounting component (20) mounting portion (a space (R) in the figure) surrounded by the pad row, wherein the surface mounting component (20) is mounted. The surface mount component of the other pad row is wired from the outside to the inside of the surface mount component (20) mounting portion through a portion corresponding to the unused terminal (22) of the surface mount component (20) of the one pad row. A portion of the (20) corresponding to the unused terminal (22) is wired to the outside of the surface mount component (20) mounting portion, and at least a portion of the surface mount component (20) corresponding to the unused terminal (22). Has a conductor circuit (12) covered with an insulating layer (13) '', which enables the wiring between the pads for surface mounting components (20) of the board to be routed. Effective utilization, improvement of wiring efficiency, accompanying reduction of board size, Thus, it is possible to provide a surface-mounting printed wiring board (10) capable of ensuring high reliability of the substrate due to layering and further reduction of through holes.

That is, according to the printed wiring board (10), the space (R) surrounded by the pads (11) can be effectively used, and the conductor circuits (12) can be formed without passing through the through holes. ) Can be formed, so that the wiring density of the substrate can be improved. Further, since the through hole is hardly required, the manufacturing thereof is easy and the reliability of conduction of the substrate can be improved.

Further, in manufacturing the printed wiring board (10) according to the present invention, when designing each wiring pattern, a conductor circuit is provided on a portion of the substrate corresponding to the unused terminal (22) of the surface mount component (20). It is only necessary to form (12), conventional equipment can be used as it is, and printed wiring board (1
The cost of 0) can be reduced.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view of a printed wiring board according to the present invention.

FIG. 2 is a partially enlarged plan view of a II-II line portion of FIG.

FIG. 3 is a partially enlarged side view of the printed wiring board according to the present invention.

FIG. 4 is a partially enlarged plan view of a conventional printed wiring board.

FIG. 5 is an enlarged plan view showing an example of a surface mount component.

[Explanation of symbols]

10 ... Printed wiring board, 11 ... Pad, 12 ... Conductor circuit, 13 ...
Insulation layer, 20 ... Surface mount component, 21 ... Terminal, 22 ... Unused terminal, 30 ... (Conventional) printed wiring board, 31 ... Pad,
32 ... Unused pad, 33 ... Through hole, 34 ... Conductor circuit, R ... Space

Claims (1)

[Claims] 1. A surface mounting printed wiring board having a pad row in which pads connected to terminals of the surface mounting component are aligned, and a surface mounting component mounting portion surrounded by the pad row, wherein the surface mounting component is mounted. Wiring from the outside through the portion corresponding to the unused terminal of the surface mount component of the one pad row to the inside of the surface mount component mounting portion and through the portion corresponding to the unused terminal of the surface mount component of the other pad row A printed wiring board having a conductor circuit which is wired to the outside of the surface mount component mounting portion and at least a portion of the surface mount component corresponding to the unused terminal is covered with an insulating layer.