JPH08279706A - Distributed constant line - Google Patents

Abstract

PURPOSE: To provide a distributed constant circuit within the small volume having a long electric length as designed by folding zigzag a flexible printed circuit board composed of two layers of a signal line layer and a ground layer for each fixed length and convolving the signal layer and the ground layer while inverting the front side and the rear side. CONSTITUTION: Closely checking a section C, where an EPC is folded zigzag and dropped from a hill to a dale, and the section where it is moved upward from the dale to the hill, it is found that continuous signal lines 11 at both sections face each other. More closely checking the place where a front face cover coat layer 5 at the section and a front face ground layer 2a at a section D are interposed between these confronted signal lines 11, these signal lines 11 are shielded each other by the ground layer 2a and do not directly face each other. Therefore, electrostatic coupling between signal lines is eliminated. This is similarly established even concerning a section E dropped from the hill, where the continuous signal lines 11 face each other, to the dale and a section F raised from the dale to the hill as well. Therefore, the distributed constant circuit having the required electric length can be easily provided as designed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed constant line, and more particularly, to a signal line layer and a ground layer by folding a flexible printed circuit consisting of two layers of a signal line layer and a ground layer in a zigzag pattern at regular intervals. The present invention relates to a distributed constant line in which the front and back sides are reversed to convolve.

[0002]

2. Description of the Related Art A conventional example of a distributed constant line will be described with reference to FIG. FIG. 4 is a diagram illustrating a conventional example in which a distributed constant line using a flexible printed circuit (FPC) including two layers of a signal line layer and a ground layer is used as a distributed constant filter line. 4 (a) is a front view and FIG. 4 (b) is FIG.
The figure which shows the cross section along the AA line of (a), and FIG.4 (c) is a back view.

In FIG. 4, 1 is a signal line layer, and 11
Are signal lines constituting the signal line layer 1. 2 indicates a ground layer. 4 is an insulating layer, which is a signal line layer 1 and a ground layer 2
And the signal line 11 and the ground layer 2 are insulated from each other. The signal line 11 is made of an extremely thin conductive thin film, and is formed on the surface of the insulating layer 4 by printing. The ground layer 2 is made of a conductive thin film formed on the entire back surface of the insulating layer 4. Reference numeral 3 indicates a front surface cover coat, and 5 indicates a rear surface cover coat. For convenience of description, the front surface cover coat 3 is omitted in FIG. 4A, and the back surface cover coat 5 is omitted in FIG. 4C.

The signal line layer 1 and the ground layer 2 shown in FIG.
It is possible to construct a distributed constant filter line, a distributed constant delay line having a constant characteristic impedance, or another distributed constant transmission line using the FPC consisting of two layers. That is, the signal line 11 forming the signal line layer 1 and the ground layer 2 face each other with the insulating layer 4 in between, and form a capacitor that forms a distributed capacitance therebetween. This distributed capacitance is determined by appropriately designing and adjusting the width of the signal line 11 made of a conductive thin film, the length of the signal line 11, the thickness of the insulating layer 4, and the material. The capacitor forming this distributed capacitance can be used as a distributed constant filter line for noise elimination, or can be generally used as a distributed constant transmission line.

By increasing the FPC length, that is, by increasing the electrical length, a distributed constant filter line having a good cutoff characteristic or a distributed constant delay line having a constant characteristic impedance can be obtained. That is, the distributed constant filter line or the distributed constant delay line is formed between the signal line 11 and the ground layer 2 by the number of signal lines 11 respectively. Here, when it is desired to store a long FPC in a small volume, the FPC composed of two layers of the signal line 11 and the ground layer 2 shown in FIG. 4 is folded back in a zigzag at regular intervals and folded. There is. FIG. 5 is a diagram showing a cross section of a distributed constant filter line or a distributed constant transmission line configured by folding back the FPC shown in FIG. 4 in a zigzag at constant lengths and folding it.

[0006]

By the way, the signal line layer 1
By simply folding back the FPC consisting of two layers, the ground layer 2 and the ground layer 2, the same signal line layers 1 face each other with the surface cover coat layer 3 in between, and the continuous signal lines 11 that face each other. The comrades are electrostatically coupled to generate stray capacitance. This will be described with reference to FIG. 5. Focusing on a portion indicated by C where the FPC is folded back in a zigzag manner and descending from a mountain to a valley, and a portion indicated by D rising from a valley to a mountain, both portions are continuous. Signal line 11
The comrades face each other with the two layers of the surface cover coat layer 3 in between. In this way, the signal lines 11 that are continuous with each other oppose each other, so that they are electrostatically coupled to generate a stray capacitance. The distributed capacitance between the signal line 11 and the ground layer 2 is
As described above, the design adjustment can be made by paying attention to the width of the signal line 11 made of the conductive thin film, the length of the signal line 11, the thickness of the insulating layer 4, and the material, but stray capacitance occurs between the signal lines 11. In this case, since the stray capacitance is indefinite, the distributed capacitance cannot be obtained as designed due to the stray capacitance, and the required electrical length or characteristic impedance cannot be obtained.

According to the present invention, a flexible printed circuit composed of two layers, a signal line layer and a ground layer, is folded back in a zigzag pattern at regular intervals, and the signal line layer and the ground layer are turned upside down and folded up. It is intended to provide a distributed constant line that solves the above problems.

[0008]

A flexible printed circuit composed of two layers, a signal line layer 1 having a signal line 11 formed thereon and a ground layer 2, is folded back in a zigzag pattern at regular intervals to form the signal line layer 1.
And the ground layer 2 are turned upside down to form a convolved distributed constant transmission line. The flexible printed circuit constitutes a distributed constant transmission line in which the signal line layer 1 and the ground layer 2 are formed on both front and back surfaces of the insulating layer 6.

Further, the signal line layers 1 and the ground layers 2 are alternately formed on both the front and back surfaces of the insulating layer 6 at regular intervals, and the signal lines 11 on the front and back sides adjacent to each other are electrically connected. A distributed constant transmission line electrically connecting the front and back ground layers 2a and 2b adjacent to each other was constructed. Here, the flexible printed circuit including two layers of the signal line layer 1 and the ground layer 2 on which the signal line 11 is formed is folded back in a zigzag at a constant length so that the signal line layer 1 and the ground layer 2 are turned upside down. We constructed a distributed constant filter line characterized by a convolutional configuration.

The flexible printed circuit has a distributed constant filter line in which the signal line layer 1 and the ground layer 2 are formed on both front and back surfaces of the insulating layer. Also, the signal line layer 1
And the ground layer 2 are alternately formed on the front and back surfaces of the insulating layer 6 at regular intervals, and the signal lines 11 on the front and back adjacent to each other are electrically connected to each other and the ground layers 2a on the front and back adjacent to each other. A distributed constant filter line for electrically connecting 2b to each other was constructed.

Further, a flexible printed circuit composed of two layers of the signal line layer 1 and the ground layer 2 on which the signal line 11 is formed is zigzag-folded at a constant length so that the signal line layer 1 and the ground layer 2 are arranged on the front and back sides. We constructed a distributed constant delay line that is inverted and convolved. Further, the flexible printed circuit constitutes a distributed constant delay line in which the signal line layer 1 and the ground layer 2 are formed on both front and back surfaces of the insulating layer.

Then, the signal line layer 1 and the ground layer 2 are alternately formed on the front and back surfaces of the insulating layer at regular intervals, and the signal lines 11 on the front and back adjacent to each other are electrically connected to each other. A distributed constant delay line for electrically connecting the front and back ground layers 2a and 2b adjacent to each other was constructed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining an embodiment in which a distributed constant line using an FPC composed of two layers of a signal line layer and a ground layer is used as a distributed constant filter line.
1A is a front view, FIG. 1B is a view showing a cross section taken along line AA of FIG. 1A, and FIG. 1C is a back view. Figure 2
FIG. 2 is a diagram showing a cross section of a line formed by folding and folding the FPC shown in FIG. 1. FIG. 3 is a perspective view of the line of FIG. 2 mounted on a substrate.

In FIG. 1, 1a indicates a front surface signal line layer, and 1b indicates a rear surface signal line layer. Reference numeral 20 is a through hole that penetrates the signal line 11 forming the signal line layer 1. Two
Reference symbol a denotes a front surface ground layer, and reference symbol 2b denotes a back surface ground layer. Reference numeral 40 is a through hole for penetrating a connecting lead wire that electrically connects the front surface ground layer 2a and the back surface ground layer 2b. Reference numeral 5 represents a front surface cover coat, and 7 represents a back surface cover coat. Reference numeral 6 is an insulating layer. For convenience of explanation, the surface cover coat 5 is omitted in FIG.
In (c), the back cover coat 7 is omitted.

Also in the case of this embodiment, similarly to the conventional example, the signal line 11 constituting the signal line layer 1 and the ground layer 2 are opposed to each other via the insulating layer 6, and a capacitor forming a distributed capacitance therebetween is formed. I am configuring. The distributed capacitance is determined by appropriately designing and adjusting the width of the signal line 11 made of a conductive thin film, the length of the signal line 11, the thickness of the insulating layer 6, and the material. The design adjustment of the width of the signal line 11 forming the signal line layer is also performed by changing the design periodically.
The capacitor forming this distributed capacitance can be used as a distributed constant filter line for noise elimination, or can be generally used as a distributed constant transmission line.

Here, in FIG. 1, when the portions of the FPC that are folded back are designated by the symbols A to H, the portion B on the back surface is shown.
Of the signal line layer 1b is continuous with the signal line layer 1a of the front surface portion C via the through hole 20, and the signal line layer 1a of the front surface portion C is connected to the rear surface portion D via the through hole 20.
The signal line layer 1b of the rear surface portion D is continuous with the signal line layer 1a of the front surface portion E through the through hole 20, and so on. The ground layer 2a on the front surface and the ground layer 2b on the back surface are indicated by diagonal lines. The front surface ground layer 2a and the back surface ground layer 2b are electrically connected to each other via a connecting conductor penetrating the through hole 40.

In FIG. 1, a one-dot chain line and a two-dot chain line are shown. The one-dot chain line shows where the turning point is mountain-folded, and the two-dot chain line shows where the turning point is valley-folded. ing. When the FPC shown in FIG. 1 is folded back in zigzag along the chain line and folded, a distributed constant filter line or distributed constant delay line as shown by the cross section in FIG. 2 is constructed. That is, the portions A to H shown in FIG. 1 correspond as shown in FIG.

Referring to FIG. 2, focusing on the portion C where the FPC is folded back in a zigzag manner and the portion C descending from the mountain to the valley and the portion D rising from the valley to the mountain, the continuous signal lines 11 of both portions face each other. However, the surface cover coat layer 5 of the portion C, the surface cover coat layer 5 of the portion D, the surface ground layer 2a of the portion D, and the insulating layer 6 are interposed between the signal lines 11 facing each other. Here, paying attention particularly to the fact that the surface ground layer 2a of the portion D is interposed between the continuous signal lines 11 of both facing portions, these signal lines 1
The ones are shielded from each other by the ground layer 2a and are not directly opposed to each other, thereby eliminating the electrostatic coupling between the signal lines. The above is the part E where the continuous signal lines 11 descend from the opposite mountain to the valley and the part F where the consecutive signal lines 11 rise from the valley to the mountain.
Similarly holds true for.

As described above, the distributed constant line of the present invention is
A flexible printed circuit consisting of two layers, a signal line layer and a ground layer, is folded back in a zigzag at regular intervals, and the signal line layer and the ground layer are turned upside down to form a convolution structure. The signal lines forming the layers are shielded by the ground layer, the signal lines do not directly face each other, and the stray capacitance is not generated by eliminating the electrostatic coupling between the signal lines. Therefore, due to the indefinite stray capacitance that is the result of this electrostatic coupling, the distributed capacitance between the signal line and the ground layer cannot be made as designed, and the electrical length is compared with the designed electrical length. Then, the inconvenience of being shifted to the shorter side is solved, and a distributed constant filter line, a distributed constant delay line, and generally a distributed constant line having a required designed electrical length or characteristic impedance can be easily obtained.

[0020]

As described above, according to the present invention, a flexible printed circuit including two layers of a signal line layer and a ground layer is zigzag-folded at regular intervals to form a signal line layer. It is possible to construct a distributed constant line that can be accommodated in a small volume with a long electrical length as designed by inverting the ground layer so that it is convoluted so that the opposing signal lines are shielded by the ground layer. .

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of a distributed constant line,
1 (a) is a front view, and FIG. 1 (b) is A-A in FIG. 1 (a).
The figure which shows the cross section along a line, FIG.1 (c) is a back view.

FIG. 2 is a diagram showing a cross section of the line shown in FIG.

FIG. 3 is a perspective view of the line of FIG.

FIG. 4 is a diagram illustrating a conventional example of a distributed constant line,
4 (a) is a front view, and FIG. 4 (b) is A-A in FIG. 4 (a).
The figure which shows the cross section along a line, FIG.4 (c) is a back view.

5 is a diagram showing a cross section of the distributed constant line shown in FIG.

[Explanation of symbols]

 1 signal line layer 11 signal line 2 ground layer 2a front ground layer 2b back ground layer 6 insulating layer

Claims (9)

[Claims] 1. A flexible printed circuit comprising two layers of a signal line layer having a signal line and a ground layer is folded back in a zigzag at a constant length so that the signal line layer and the ground layer are turned upside down. A distributed constant transmission line characterized by the above. 2. The distributed constant transmission line according to claim 1, wherein the flexible printed circuit has a signal line layer and a ground layer formed on both front and back surfaces of an insulating layer. Transmission line. 3. The distributed constant transmission line according to claim 2, wherein the signal line layer and the ground layer are alternately formed on both front and back surfaces of the insulating layer at regular intervals, and signals on the front and back surfaces adjacent to each other are formed. A distributed constant transmission line characterized in that the lines are electrically connected to each other and the ground layers on the front and back sides adjacent to each other are electrically connected to each other. 4. A convoluted structure in which a flexible printed circuit including two layers of a signal line formed with a signal line and a ground layer is folded back in a zigzag at regular intervals so that the signal line layer and the ground layer are turned upside down. A distributed constant filter line characterized by the above. 5. The distributed constant filter line according to claim 4, wherein the flexible printed circuit has a signal line layer and a ground layer formed on both front and back surfaces of an insulating layer. Filter track. 6. The distributed constant filter line according to claim 5, wherein the signal line layer and the ground layer are alternately formed on both the front and back surfaces of the insulating layer at regular intervals, and signals on the front and back surfaces adjacent to each other are formed. A distributed constant filter line, characterized in that the lines are electrically connected to each other and the ground layers adjacent to each other are electrically connected to each other. 7. A convoluted structure in which a flexible printed circuit including two layers of a signal line formed with a signal line and a ground layer is folded back in a zigzag at a constant length so that the signal line layer and the ground layer are turned upside down. A distributed constant delay line characterized by the above. 8. The distributed constant filter line according to claim 7, wherein the flexible printed circuit has a signal line layer and a ground layer formed on both front and back surfaces of an insulating layer. Delay line. 9. The distributed constant filter line according to claim 8, wherein a signal line layer and a ground layer are alternately formed on both front and back surfaces of the insulating layer at regular intervals, and signals on the front and back surfaces adjacent to each other are formed. A distributed constant delay line, characterized in that the lines are electrically connected to each other and the ground layers on the front and back sides adjacent to each other are electrically connected to each other.