JP2001144451A - Laminated wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated wiring board which can be increased in degree of integration without increasing the number of laminated layers nor incorporating any useless part and can make signal lines having different characteristic impedances to be able to coexist in one substrate. SOLUTION: In a laminated wiring board 1, a conductor layer which is different from a conductor layer used as a ground layer in a certain block is used as a ground layer in another block. In other words, a conductor layer 11 which is different from a conductor layer 12 used as a ground layer 12A in a block A is used as a ground layer 11B in a block B. In addition, a conductor layer which is different from a conductor layer used as a signal line in a certain block is used as a signal line in another block. In other words, the conductor layer 12 which is different from the conductor layer 11 used as a signal line 11A in the bock A is used as a signal line 12B in the block B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated wiring board formed by laminating a conductor layer and an insulating layer. More specifically,
The present invention relates to a laminated wiring board in which a signal line as a part of a conductor layer has a specific characteristic impedance in relation to another conductor layer.

[0002]

2. Description of the Related Art Conventionally, in a laminated wiring board, a ground layer is arranged on both sides or one side in the thickness direction of a signal line so that the signal line has a specific characteristic impedance. Some of such wiring boards have different characteristic impedances for a plurality of signal lines in one board.

For example, a strip line shown in FIG. 16 and a microstrip line shown in FIG. 17 are examples. The strip lines in FIG.
02 and 103 are sandwiched between ground layers 104 and 105 which are provided on the upper and lower sides and are entirely solid. Each signal line and each ground layer are insulated from each other by insulating layers 106 and 107. The microstrip line in FIG. 17 is configured by arranging a solid ground layer 115 on one side of the signal lines 111, 112 and 113. Each signal line and the ground layer are mutually insulated by the insulating layer 117. In the strip line of FIG. 16, the characteristic impedance of each of the signal lines 101, 102, and 103 is made different by giving a difference in the signal line width while keeping the thickness of the insulating layer constant. The same applies to the microstrip line in FIG.

Alternatively, FIG. 18 (strip line),
As shown in FIG. 19 (microstrip line), the characteristic impedance of each signal line can also be different by making the line width constant and making a difference in the interlayer distance instead. That is, in the strip line of FIG.
The solid ground layers 124 and 125 and the signal lines 121 and
122, 123, a partial ground layer 128,
129 are provided. In the microstrip line shown in FIG. 19, the solid ground layer 135 and the signal line 1
31, 132, 133, a partial ground layer 1
38 and 139 are provided.

[0005]

However, the conventional technique for adjusting the characteristic impedance of the laminated wiring board has the following problems.

The problem with the stripline shown in FIG. 16 and the microstripline shown in FIG. 17 is that it is difficult to satisfy both design requirements and manufacturing requirements. The reason is as follows. That is, the line width of the signal lines 101 and 111 having a characteristic impedance of 75Ω is generally used frequently.
It is assumed that the interlayer distance and the like are set to 1 mm. Then, the signal lines 102 and 112 having a characteristic impedance of 50Ω
Is 0.25 mm thick and has a characteristic impedance of 28 mm.
0.6 mm for the line width of the Ω signal lines 103 and 113
Is required. For this reason, the area occupied by the signal lines in the plane of the board is large, which is an obstacle to high integration. This makes the design extremely difficult.

On the other hand, if the line width of the signal lines 103 and 113 having a characteristic impedance of 28Ω is set to 0.1 mm, which is easy to design, the line width of the signal lines 101 and 111 having a characteristic impedance of 75Ω is set to about 0.01 mm. Must be as small as This is difficult to manufacture. For this reason, if signal lines having different characteristic impedances coexist on a single substrate, it is difficult to satisfy both design requirements and manufacturing requirements.

On the other hand, the strip line shown in FIG.
The problem with the microstrip line is that the number of layers is large. Therefore, the number of steps in the manufacturing process is large. Also, the partial ground layers 128, 12
9, 138, 139 include blank areas of large area. The blank portion is a useless portion in the sense that the signal does not pass. It can be seen that this is an obstacle to high integration of wiring.

The present invention has been made to solve the above-mentioned problems of the conventional laminated wiring board. That is, the problem is that by changing the combination of conductor layers used as signal lines and ground layers for each block, high integration can be achieved without increasing the number of layers or incorporating unnecessary parts. Another object of the present invention is to provide a laminated wiring board that can easily coexist signal lines having different characteristic impedances in one substrate.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated wiring board comprising a conductor layer and an insulating layer, wherein a certain conductor layer is used as a signal line. Another conductor layer has a plurality of blocks used as its ground layer, and a conductor layer different from the conductor layer used as a ground layer in one block is used as a ground layer in another block, A conductor layer different from the conductor layer used as a signal line is used as a signal line in another certain block described above.

In this laminated wiring board, the combination of a conductor layer used as a signal line and a conductor layer used as a ground layer differs for each block. For this reason, it is difficult to design or manufacture such that the signal line has a desired characteristic impedance for each block or that the signal line has as many signal lines as possible with as few layers as possible. It is possible without it. That is, the degree of freedom in design is high. Note that the ground layer referred to in the present application includes a power supply layer.

In the laminated wiring board of the present invention, it is not necessary to have a solid ground layer on the entire surface. In other words, it suffices that a ground layer having a line width substantially equal to the line width of the signal line exists only above and below the signal line or only one of the signal lines. Therefore, the present invention is a laminated wiring board in which a conductor layer and an insulating layer are laminated, and has a block in which a certain conductor layer is used as a signal line and another certain conductor layer is used as a ground layer thereof. In a certain block, it is established that the width of the ground layer is in the range of 0.8 to 3 times the width of the signal line. Particularly preferred are 0.9 to 1.
It is within the range of 6 times.

The role of the ground layer is to cut off the interaction between the current flowing through the signal line and an external electromagnetic field, in addition to adjusting the characteristic impedance based on the arrangement relationship with the signal layer.
In the multilayer wiring board of the present invention, at least one conductor layer is used as a ground layer for each block. Therefore, even if there is no solid ground layer on the entire surface, one of the conductor layers exists as the ground layer in almost the entire area of the substrate.
Therefore, practically sufficient blocking performance is ensured.

The laminated wiring board of the present invention is particularly meaningful in that a conductor layer used as a signal line in a certain block is used as a ground in another certain block. Alternatively, it is meaningful to configure the characteristic impedance of the signal line and its ground layer to be different depending on the block.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the laminated wiring board of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view showing an example of an embodiment in which the present invention is embodied as a six-layer substrate. Laminated wiring board 1 shown in FIG.
Are conductor layers 11 to 1 insulated from each other by an interlayer insulating layer.
And six conductor layers. FIG. 1 shows a cross section of a portion extending over three blocks of blocks A, B, and C in the multilayer wiring board 1.

The conductor layer 11 includes a signal line 11A in the block A.
And a ground layer or a power layer (hereinafter simply referred to as a “ground layer”, the same applies to other ground layers) in block B.
1B, and block C forms a signal line 11C.
The conductor layer 12 forms a ground layer 12A in the block A,
The block B forms the signal line 12B, and the block C forms the signal line 12C. The conductor layer 13 forms the signal line 13A in the block A, and forms the ground layer 13B extending from the block B to the block C. In the conductor layer 14, the block A forms the signal line 14A, the block B forms the signal line 14B, and the block C forms the ground layer 14C. The conductor layer 15 forms a ground layer 15A extending from the block A to the block B, and the block C forms a signal line 15C. In the conductor layer 16, the block A forms the signal line 16A, the block B forms the signal line 16B, and the block C forms the signal line 16C.

In the laminated wiring board 1, a conductor layer different from a conductor layer used as a ground layer in a certain block is used as a ground layer in another block. For example, a conductor layer 11 different from the conductor layer 12 used as the ground layer 12A in the block A is used as the ground layer 11B in the block B. Further, a conductor layer different from a conductor layer used as a signal line in a certain block is used as a signal line in another certain block. For example, a conductor layer 12 different from the conductor layer 11 used as the signal line 11A in the block A is used as the signal line 12B in the block B. In addition, there is a conductor layer used as a signal line in a certain block and used as a ground layer in another certain block. For example, the conductor layer 11 is used as the signal line 11A in the block A and is used as the ground layer 11B in the block B. There is no solid ground layer on the entire surface.

The line width of each signal line is 0.1
mm. On the other hand, the block width of each block and the width of each ground layer are all three times 0.3 mm.
It is. In any of the blocks A, B, and C, there is always a conductor layer used as a ground layer.

In the multilayer wiring board 1, the signal lines 12B, 13A, 14A, 14B having a strip line structure and the signal lines 11A, 11C, 1 having a microstrip line structure are also provided.
2C, 15C, 16A, 16B, and 16C coexist. The characteristic impedance of each signal line is 11C,
13A, 14A and 16C are 50Ω, and 11A and 12C
28Ω for B, 12C, 14B, 15C, 16A, 16B
It is. That is, signal lines having different characteristic impedances coexist.

The outline of the manufacturing process of the laminated wiring board 1 is as follows. First, two double-sided copper-clad boards are prepared, and each copper foil is patterned on both sides. Then, an interlayer insulating layer is sandwiched between the two double-sided copper-clad boards, and further, a prepreg and a conductor layer are arranged outside the two double-sided copper-clad boards and pressed. Alternatively, as another manufacturing method, a method in which an interlayer insulating layer and a conductor layer are sequentially laminated on both surfaces of one double-sided copper-clad board may be used. Alternatively, there is a method in which three double-sided copper-clad boards are prepared, and a prepreg is sandwiched between the respective double-sided copper-clad boards and pressed.

As described above, in the laminated wiring board 11, as many as 11 signal lines are integrated in the area of 6 layers × 3 blocks.
In addition, signal lines having different characteristic impedances coexist on the same substrate. Nevertheless, since the line widths of the signal lines are all the same, there is no difficulty in designing or manufacturing. Further, since the ground layer exists in each block, the block performance is not so inferior as compared with the case where the entire surface has a solid ground layer.

FIG. 2 is a sectional view showing an example of an embodiment in which the present invention is embodied as a seven-layer substrate. In the laminated wiring board 2 shown in FIG. 2, the ground layers and the signal lines are alternately laminated in each block, and the order of the ground layers and the signal lines is switched between adjacent blocks. Thus, ten signal lines are integrated in the area of 7 layers × 3 blocks. If an attempt is made to realize a configuration similar to that of FIG. 2 on the premise of a solid ground layer as in the prior art, the result is as shown in FIG. In this case, 7 layers x
There are only nine signal lines in the area of three blocks. As described above, in the multilayer wiring board 2 of FIG. 2, the degree of integration is improved by changing the combination of the conductor layer used as the signal line and the ground layer for each block.

In the structure of FIG. 20, there are only three conductor layers used as signal lines, whereas in the structure of FIG. 2, all seven layers are used as signal lines. Therefore, a circuit having the structure shown in FIG. 2 can be used even for a circuit requiring four or more conductor layers used as signal lines. On the other hand, the structure shown in FIG. 20 cannot be used for such a purpose. Such applications include, for example, CSP
Signal extraction from a package is an example. Further, in the structure of FIG. 20, since other signal lines are arranged without sandwiching the ground layer beside the signal lines, mutual interference between the signal lines is likely to occur. In contrast, in the structure of FIG.
A ground layer is interposed between the signal line and another signal line arranged on the side of the signal line. Thereby, mutual interference between the signal lines is prevented.

[0024]

EXAMPLE According to the results of a test conducted by the present inventor through computer simulation, the laminated wiring board of the present invention has
Adjustment of the characteristic impedance by the line width of the signal line can be performed in the same manner as in the case of the conventional laminated wiring board. Also,
The characteristic impedance can be adjusted also by the width of the ground layer. And even though the ground layer is not a solid film, a slight displacement between the signal line and the ground layer does not have a great effect. The following describes these test results.

(Test 1) This test is a test on the relationship between the line width of the signal line and the characteristic impedance. This test was performed for the two types of structures shown in FIGS.
FIG. 3 shows a structure in which the signal line 30 is sandwiched between a solid ground layer 31 and a narrow ground layer 32. FIG. 4 shows that the signal line 30 has a narrow ground layer 32 at both the upper and lower sides.
33. The test conditions were two types, Table 1 and Table 2. The conditions in Table 1 are conditions in which the width G of the ground layers 32 and 33 is increased by 0.125 mm from the width S of the signal line 30. The conditions in Table 2 are such that the width G of the ground layers 32 and 33 is increased by 0.025 mm from the width S of the signal line 30.

[0026]

[Table 1]

[0027]

[Table 2]

The test results under the conditions of Table 1 are as shown in the graph of FIG. In this graph, the horizontal axis is the width S (mm) of the signal line 30, and the vertical axis is its characteristic impedance (Ω). In this graph, the curve labeled "basic" is for a structure in which a signal line is sandwiched between solid ground layers both above and below. According to this graph, in both the structure of FIG. 3 and the structure of FIG. 4, these characteristic impedances are inclined almost in parallel with a certain "basic" curve.
Further, the curve "Basic" is located very close to the curves of the structure of FIG. 3 and the structure of FIG. Therefore, adjustment of the characteristic impedance by the line width of the signal line
This can be performed in the same manner as in the case of a conventional laminated wiring board.

The test results under the conditions shown in Table 2 were as shown in the graph of FIG. In this case, the structure shown in FIG.
Both structures are inclined almost in parallel with the “basic”. Further, the curve "Basic" is located very close to the curves of the structure of FIG. 3 and the structure of FIG. This makes it possible to adjust the characteristic impedance according to the signal line width.
This can be performed in the same manner as in the case of a conventional laminated wiring board.

(Test 2) The next test is a test of the relationship between the width of the ground layer and the characteristic impedance. This test is
The three types of structures shown in FIGS. 7 to 9 were performed. In FIG. 7, the signal line 30 is sandwiched between a solid ground layer 31 and a narrow ground layer 34 from above and below, and the width of the narrow ground layer 34 is changed. FIG. 8 shows a case where the signal line 30 is sandwiched between ground layers 34 and 36 having a narrow width both above and below, and the width of only one of the ground layers 34 is changed. FIG. 9 shows a configuration in which the signal line 30 is sandwiched between ground layers 34 and 36 having a narrow width in both the upper and lower directions, and the width of both ground layers 34 and 36 is changed. Also, FIG.
In each of FIGS. 9A and 9B, narrow ground layers 35 are also arranged on the side of the signal line 30. Here, the width S of the signal line 30 is 0.1 mm, the width of the ground layer 35 is 0.125 mm, and the gap between the ground layer 35 and the signal line 30 is 0.1125 mm. The width G of the upper and lower ground layers having a fixed width is set to 0.125 mm. The width of the upper and lower ground layers whose width is changed is represented by a symbol G '. The test conditions were as shown in Table 3.

[0031]

[Table 3]

The test results under the above conditions were as shown in the graph of FIG. In this graph, the horizontal axis represents the width G ′ (mm) of the ground layer, and the vertical axis represents the characteristic impedance (Ω). According to this graph, FIGS.
All curves in the structure of the above are inclined substantially linearly. Further, these curves are located substantially close within the range shown. This indicates that the characteristic impedance can be adjusted by the width G 'of the ground layer within the range.

(Test 3) This test is a test for confirming how the characteristic impedance is affected by the displacement between the signal line and the ground layer. This test was performed for four types of structures shown in FIGS. FIG. 11 shows that the signal line 30 is sandwiched between a solid ground layer 31 and a narrow ground layer 34 from above and below.
Further, the position shift amount Δ of the ground layer 34 is changed. In FIG. 12, the signal line 30 is sandwiched between ground layers 34 and 36 having a narrow width in both the upper and lower directions, and the positional deviation amount Δ of only one of the ground layers 36 is changed. Further, FIG. 13 shows that the signal line 30 is sandwiched between the ground layers 34 and 36 having a narrow width at the top and bottom, and
4 and the position shift amount Δ of the ground layer 36 is changed in the same direction both vertically. Also, FIG.
The signal line 30 is sandwiched between the ground layers 34 and 36 having a narrow width both above and below.
Is changed in the vertical direction in the opposite direction.

11, 12, 13, and 14, the narrow ground layers 35, 35 are also provided beside the signal lines 30.
Has been arranged. Here, the width S of the signal line is 0.1 mm
And the width of the ground layer 35 is 0.125 mm.
Further, the gap between the ground layer 35 and the signal line 30 is 0.1125 mm. Also, the ground layers 34, 36
Has a width G of 0.125 mm. The displacement amount Δ is 0 to
It was changed by 0.02 mm in a range of 0.08 mm.

The test results under the above conditions are as shown in the graph of FIG. In this graph, the horizontal axis represents the amount of displacement Δ (mm) of the ground layer, and the vertical axis represents the characteristic impedance (Ω). Note that the test results of the structures in FIGS. According to this graph, in all of FIGS. 11, 12, 13, and 14, when the displacement amount Δ is within the range of 0.08 mm, the characteristic impedance is smaller than when the displacement amount Δ is 0 mm. There is no significant change.
Therefore, even if there is a slight displacement between the signal line 30 and the ground layers 34 and 36, the characteristic impedance is not so greatly affected.

As described in detail above, in the laminated wiring board 1 of the present embodiment, as shown in FIG. 1, the combination of the conductor layer used as the signal line and the conductor layer used as the ground layer is different for each block. Is different. Also,
Some conductor layers are used as signal lines in some blocks and as ground layers in some other blocks. As a result, signal lines having different characteristic impedances coexist on the same substrate. Also, since a ground layer exists in each block, it is not necessary to have a solid ground layer on the entire surface. In addition, if the width of the ground layer is within the range of 0.8 to 3 times the width of the signal line, and especially within the range of 0.9 to 1.6 times, the solid ground layer is entirely solid. Without this, practically sufficient blocking performance is ensured. Therefore, in the laminated wiring board 1, higher integration is achieved as compared with the conventional one.

The present embodiment is merely an example, and does not limit the present invention in any way. Therefore, naturally, the present invention can be variously modified and modified without departing from the gist thereof. For example, the specific arrangement of the signal lines and the ground layers need not be the one shown in FIGS.

[0038]

As is apparent from the above description, according to the present invention, by changing the combination of the conductor layers used as the signal lines and the ground layers for each block, the number of layers can be increased or unnecessary parts can be built in. There has been provided a multilayer wiring board that can be highly integrated without causing any trouble and that can easily coexist signal lines having different characteristic impedances on one substrate.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an embodiment embodied as a six-layer substrate.

FIG. 2 is a sectional view showing an example of an embodiment embodied as a seven-layer substrate.

FIG. 3 is a diagram showing a configuration of a laminated wiring board in Test 1.

FIG. 4 is a diagram showing a configuration of a laminated wiring board in Test 1.

5 is a graph showing the results of a test 1 performed under the conditions shown in Table 1. FIG.

6 is a graph showing a result of a test 1 performed under the conditions shown in Table 2. FIG.

FIG. 7 is a view showing a configuration of a laminated wiring board in Test 2;

FIG. 8 is a diagram showing a configuration of a laminated wiring board in Test 2;

FIG. 9 is a diagram showing a configuration of a laminated wiring board in Test 2.

FIG. 10 is a graph showing the results of performing test 2.

FIG. 11 is a view showing a configuration of a laminated wiring board in Test 3;

FIG. 12 is a view showing a configuration of a laminated wiring board in Test 3;

FIG. 13 is a diagram showing a configuration of a laminated wiring board in Test 3.

FIG. 14 is a diagram showing a configuration of a laminated wiring board in Test 3;

FIG. 15 is a graph showing the results of Test 3.

FIG. 16 is a cross-sectional view illustrating a configuration of a laminated wiring board in a conventional strip line.

FIG. 17 is a cross-sectional view showing a configuration of a laminated wiring board in a conventional microstrip line.

FIG. 18 is a cross-sectional view showing a configuration of a laminated wiring board in a conventional strip line.

FIG. 19 is a cross-sectional view showing a configuration of a laminated wiring board in a conventional microstrip line.

FIG. 20 is a cross-sectional view showing a conventional laminated wiring board having a seven-layer structure.

[Explanation of symbols]

 Reference Signs List 1 laminated wiring board 2 laminated wiring board 11B, 12A, 13B ground layer 14C, 15A ground layer 11A, 11C, 12B signal line 12C, 13A, 14A signal line 14B, 15C, 16A signal line 16B, 16C signal line

Claims (4)

[Claims] 1. A laminated wiring board comprising a conductor layer and an insulating layer laminated on each other, comprising a plurality of blocks in which one conductor layer is used as a signal line and another certain conductor layer is used as a ground layer thereof. A conductor layer different from a conductor layer used as a ground layer in a certain block is used as a ground layer in another certain block, and a conductor layer different from a conductor layer used as a signal line in the certain block is used in the other block. A laminated wiring board used as a signal line. 2. A laminated wiring board comprising a conductor layer and an insulating layer, wherein a certain conductor layer is used as a signal line and another certain conductor layer is used as its ground layer. Wherein the width of the ground layer is in the range of 0.8 to 3 times the width of the signal line. 3. The laminated wiring board according to claim 1, wherein a conductor layer used as a signal line in one block and a ground layer in another block is present. Wiring board. 4. One of claims 1 to 3
A multilayer wiring board according to any one of the preceding claims, wherein characteristic impedances of signal lines and ground layers thereof differ depending on blocks.