JP2631641B2 - Printed wiring board - Google Patents

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 having, for example, a printed wiring pattern for a large current and a printed wiring pattern for a small signal on a substrate surface.

[0002]

2. Description of the Related Art FIG. 2 is a circuit diagram of a large current control element and a small signal control element. In FIG. 2, reference numerals 2 and 4 denote transistors as high current control elements, respectively.
Reference numeral 6 denotes a transistor as a small-signal control element;
Is an emitter resistance.

FIG. 3 is a plan view of a printed wiring board on which the circuit element of FIG. 2 is mounted. On the substrate surface 12 of the printed wiring board 10 shown in FIG. 3, printed wiring patterns 14, 16 for mounting the large current control transistors 2, 4 and printed wiring patterns for mounting the small signal control transistor 6 are provided. 18
And the small-signal printed wiring pattern 2 which becomes the emitter resistor 8
0, a printed wiring pattern 22 for a large current to be a power supply line
Are formed to have the same thickness and a corresponding pattern width and shape by a well-known printed wiring technique.

[0004]

By the way, the thickness of each printed wiring pattern is t, and the printed wiring pattern for small signal 2 is
0 is the pattern width of W1, and the large current printed wiring pattern 22
, The cross-sectional area S1 of the small-signal printed wiring pattern 20 is represented by W1 × t, and the cross-sectional area S2 of the large-current printed wiring pattern 22 is represented by W2 × t.

In this case, the small signal printed wiring pattern 20
Is the cross-sectional area S1 corresponding to the resistance value of the emitter resistor 8, whereas the large-current printed wiring pattern 22 is the cross-sectional area S2 corresponding to the zero DC resistance value. W2 >> W1, so that the large-current printed wiring pattern 22 necessarily has a large pattern width W2, and occupies most of the area on the substrate surface 12 as shown in FIG.

For this reason, the conventional printed wiring board 10 has a problem that the mounting density of electronic components on the board surface is extremely low.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to reduce the area occupied by a large-current printed wiring pattern on a substrate surface and to increase the mounting density of electronic components. And

[0008]

In order to achieve the above object, in a printed wiring board according to the present invention, a first wiring pattern and a second wiring pattern having a smaller resistance value than the first wiring pattern are provided. Wiring pattern on the substrate surface,
The width of the second wiring pattern is made substantially equal to the width of the first wiring pattern by increasing the thickness dimension of the wiring pattern of the first and second wiring patterns. the continuous connection, further, that with the said first wiring pattern and the second wiring pattern
The configuration is such that branch wiring patterns branching from each are provided.

[0009] According to the above configuration, the second resistance value is reduced.
Since the width of the wiring pattern is also substantially equal to the width of the first wiring pattern, the area occupied by the second wiring pattern on the printed wiring board is reduced, and the electronic component The mounting density can be increased.

Further, since the first wiring pattern and the second wiring pattern are continuously connected, the arrangement of the first and second wiring patterns and further, the branch wiring pattern can be simplified.

In addition, since the second wiring pattern is not wide, a large number of branch wiring patterns can be formed from the second wiring pattern without any trouble.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing a cross section of a main part of a printed wiring board according to an embodiment of the present invention. In FIG. 1, the same portions as those in FIG. 3 according to the conventional example are denoted by the same reference numerals, and the description of the portions corresponding to the same reference numerals is omitted.

In the printed wiring board 23 of this embodiment,
The product of the groove width substantially equal to the pattern width W1 of the small signal printed wiring pattern 20 as the first wiring pattern on the substrate surface 12 and the large current as the second wiring pattern in FIG. Area W2 of printed wiring pattern 22
It is characterized in that a groove 24 having a groove depth d substantially equal to × t is formed, and a large-current printed wiring pattern 22 is formed in the groove 24. From the small-signal printed wiring pattern 20 and the large-current printed wiring pattern 22, printed wiring patterns 14, 16, and 18 as branch wiring patterns are formed in a branched manner.

The large current printed wiring pattern 22
Is to apply a conductive paste such as Ag-Pd to the grooves 2.
It is obtained by baking after pouring into 4.

The other structure of this embodiment is the same as that of the conventional example.

In the printed wiring board 23 of the present embodiment having the above-described configuration, the groove 24 having a cross-sectional area of a large-current printed wiring pattern 22 having a cross-sectional area having a DC resistance value of substantially zero. And the groove width of the groove 24 is substantially equal to the pattern width of the small-signal printed wiring pattern, so that the occupied area of the large-current printed wiring pattern 22 in the printed wiring board 23 is significantly reduced. Become. As a result, the mounting density of electronic components on the printed wiring board 23 can be increased. Further, when the groove width of the large current printed wiring pattern 22 is formed to be large in a structure having a small groove depth, the pattern is likely to bulge or protrude, thereby making it difficult for the cross-sectional area to be constant. According to the method, the swelling or protrusion of the pattern is unlikely to occur, so that the cross-sectional area is maintained at a predetermined value, whereby a large-current printed wiring pattern 22 having a stable resistance value can be obtained.

Further, as the wiring board, the groove width of the large current printed wiring pattern 22 can be reduced, so that the spacing between the patterns can be widened when the wiring board space is constant, thereby improving the frequency characteristics. In particular, high frequency characteristics are improved. Further, since the large-current printed wiring pattern 22 and the small-signal printed wiring pattern 20 have substantially the same pattern width, the pattern design of the wiring board can be easily performed with a simple wiring pattern. The mounting operation of the circuit element to the device can be easily performed by a simple operation.

[0018]

As is apparent from the above description, according to the present invention, for example, the area occupied on the substrate surface of the second wiring pattern formed for a large current can be reduced, and the mounting density of electronic components can be increased. Will be able to

Further, according to the present invention, since the width of the second wiring pattern can be reduced, the spacing between the patterns can be widened when the wiring board space is constant, thereby providing the wiring board with frequency characteristics, In particular, a device with improved high-frequency characteristics can be obtained.

In addition, since the first wiring pattern and the second wiring pattern are continuously connected, the arrangement of the first and second wiring patterns, and further, the branch wiring pattern can be simplified. Thus, the pattern design on the substrate can be easily performed, and the mounting operation of the circuit element on the substrate can be easily performed by a simple operation.

In addition, since the second wiring pattern is not wide, a large number of branch wiring patterns can be formed from the second wiring pattern without any trouble. This also increases the degree of freedom in pattern design. The mounting density can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view of a main part of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a circuit element mounted on a printed wiring board.

FIG. 3 is a plan view of a printed wiring board according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Printed wiring board 12 ... Substrate surface 20 ... Small signal printed wiring pattern (first wiring pattern) 22 ... High current printed wiring pattern (second wiring pattern)

Claims (1)

(57) [Claims] 1. A first wiring pattern and a second wiring pattern having a smaller resistance value than the first wiring pattern are provided on a substrate surface, and the thickness of the second wiring pattern is increased. Thereby, the width of the second wiring pattern is made substantially equal to the width of the first wiring pattern, and the first wiring pattern and the second wiring pattern are continuously connected. printed wiring board of characterized by comprising providing each branch wiring patterns branching from each of the wiring pattern and the second wiring pattern.