JP2000091801A - Connection line substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small connection line substrate with low loss, which connects a plurality of high frequency circuits where mutual fitting faces form angles and are arranged, by installing a dielectric substrate, a strip conductor and a ground conductor and forming the ground conductor to be narrower than first and second flat areas in a bend area. SOLUTION: The ground conductor 16 with a thickness of 30 μm is adhered to the back 17 of a dielectric substrate 10 by making it face a strip conductor 15. The ground conductors 16 are formed on the whole back faces of flat areas 12 and 13 in width W. The width W of a bend area is narrowed and it is narrower than the flat areas but is formed to be wider than the strip conductor 15. Since the width W of the ground conductor 16 at the back of the bend area is formed to be wide, a curvature is made to be large in the bend area and the connection line substrate can be bent at a large angle. Thus, the connection line substrate can be connected to peripheral high frequency circuit elements making the angles on the close fitting faces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection line substrate used for connecting high-frequency circuit elements for microwaves and the like, which are arranged at positions where their mounting surfaces are at an angle to each other across a corner. About.

[0002]

2. Description of the Related Art In general, high frequency circuits such as microwave bands are often formed on a planar circuit board on the same plane. However, a plurality of high-frequency circuits may be arranged at an angle of 90 degrees or the like due to attachment to a device. In order to connect these circuits, as shown in FIG. Once converted to a coaxial line, it was necessary to connect between them with a conductor having a coaxial structure. In the figure, the high-frequency circuit connecting portion 35a and the other high-frequency circuit connecting portion 35b are connected by a conductor 34 having a coaxial structure via converters 36a and 36b. The high frequency circuit connecting portion 35a is connected to the dielectric substrate 3
0a, a microstrip conductor 31a on the front surface thereof, and a ground conductor 33a on the rear surface thereof. 33b.

[0003] However, the loss in the conversion section increases as the frequency increases, and the loss is very large at an ultra-high frequency such as a millimeter wave. In addition, due to the restriction of the minimum bending radius (minimum radius of curvature),
It was not suitable for connecting two high-frequency circuits in close proximity.

In order to solve this problem, it has been proposed to form a connection line substrate by directly bending a dielectric substrate 40 having a microstrip conductor 41 and a ground conductor 43 formed on the front and back as shown in FIG.

[0005]

In the prior art, in order to connect a plurality of high-frequency circuits whose mounting surfaces are at an angle, the connection is once converted into a coaxial line at both connecting portions, and the coaxial line is connected between the two. It had to be connected by a conducting wire of the structure.
However, the loss in the converter increases as the frequency becomes higher, and it becomes a large loss at an ultra-high frequency such as a millimeter wave.

[0006] In addition, a conductor having a coaxial structure for connecting both ends has a restriction on its minimum bending radius (minimum radius of curvature),
It is not suitable for connecting two adjacent high-frequency circuits, and there are restrictions on miniaturization and low loss of the circuit.

In a structure in which the dielectric substrate is bent, the conductor on the front surface and the ground conductor on the back surface of the connection line substrate are usually connected to a high-frequency circuit element having gold electrodes by thermocompression using a gold wire or a gold ribbon. For this purpose, the surface of a metal substrate such as copper is covered with a gold plating layer.

However, the conductors on the front and back sides are hardened by the gold plating layer, and when bent, the conductors of the line on the surface of the bent area are damaged. For this reason, the bending angle cannot be made large, and there is a restriction. Further, when the connection line substrate is bent, ground conductors made of rolled copper or the like on the back surface are widely arranged on the entire back surface of the dielectric substrate, and the bending angle cannot be made large due to the physical properties of the metal. , Constraints arise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple structure of a small, low-profile connecting line board for connecting a plurality of high-frequency circuits whose mounting surfaces are arranged at an angle. The purpose is to provide at loss.

[0010]

According to the present invention, there is provided a dielectric substrate comprising a bent region, and a first flat region and a second flat region extending on both sides of the bent region. A strip conductor applied on the surface from the first flat area to the second flat area via the bent area, and a strip conductor applied on the other surface of the dielectric substrate so as to face the strip conductor. The ground conductor is wider than the strip conductor, and the ground conductor is formed to be narrower in the bent region than in the first and second flat regions.

Also, a dielectric substrate comprising a bent region, a first flat region and a second flat region extending on both sides of the bent region, and the first flat region on one surface of the dielectric substrate. And a strip conductor attached to the second flat region via the bent region, and a ground conductor attached to the one surface of the dielectric substrate adjacent to the strip conductor and wider than the strip conductor. Wherein the ground conductor is formed to be narrower in the bent region than in the first flat region and the second flat region.

The strip conductor on the first flat region and the second flat region has a base metal body and a gold layer formed on the surface of the base metal body, and the strip conductor on the bent region is a base metal body. This is to obtain the connection line conductor composed of only the body.

[0013] The thickness of the bent region of the dielectric substrate is the first.
The connection line conductor is formed to be thinner than the thickness of the flat region and the second flat region.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. As shown in FIG. 1A, a dielectric substrate 10 is, for example, a Teflon (trade name) substrate or a flexible substrate made of a synthetic resin of polyimide and has a thickness of 100 μm. are doing. The dielectric substrate 10 is bent at an angle of, for example, 90 degrees, and the flat region 12 and the flat region 13 extend on both sides of the bent region 11. Surface 1 of this dielectric substrate 10
4, a width of 280 μm and a thickness of 3 in the signal traveling direction from the flat region 12 to the other flat region 13 across the bent region 11.
A 0 μm strip conductor 15 is applied. The microstrip conductor 15 is, as shown in FIG.
Is copper, and a gold plating layer 152 having a thickness of 5 μm is formed on the surface thereof. However, as shown in FIG. do not do.

A ground conductor 16 having a thickness of 30 μm is provided on the back surface 17 of the dielectric substrate 10 so as to face the strip conductor 15. The ground conductor 16 is formed on the entire back surface of both flat regions 12 and 13 with a width W, and the width w of the bent region 11 is narrower and narrower than in the flat region, but is formed wider than the strip conductor. You. At least it is about twice the width of the strip conductor 15.

As described above, the ground conductor 16 on the back surface of the bent area
Of the connection line substrate can be bent at a large angle in the bending area. Furthermore, since the stripped conductor is removed from the gold plating layer in the bent region, the strip conductor is soft and has sufficient resistance to bending, so that it can be bent more strongly. For this reason, this connection line board can realize connection with surrounding high-frequency circuit elements (not shown) which form an angle with each other in the vicinity of each other. In addition, partial removal of the plating layer or uncovering with a mask, control of the width of the conductor on the back surface does not require any additional process in a normal circuit board manufacturing process, and the manufacturing operation can be realized very easily. . It is efficient to perform the step of partially removing the plating layer and the step of narrowing the width of the ground conductor at the same time, but they may be performed in different steps.

Here, when bending the connection line substrate,
It is preferable that the strip conductor 15 be on the outside.
This is because the impedance of this portion is increased due to the narrowing of the ground conductor in the bent region, causing insertion loss. However, the conductor 15 bites into the dielectric substrate 10 by bending the strip conductor 15 to the outside. This is because the dielectric material at that portion is made thin, so that the impedance can be lowered and compensation can be made.

Further, as shown in FIG.
By making the thickness of the zero bent region 11a smaller than the thickness of the flat regions 12a and 13a, the impedance can be reduced, and the change in impedance due to the narrowing of the ground conductor can be compensated. Bending area 11a
Can be easily bent.

FIG. 3 shows an embodiment in the case of a coplanar line. The coplanar line forms a strip conductor and a ground conductor only on one surface of a dielectric substrate. The dielectric substrate 20 is, for example, a Teflon (trade name) substrate or a synthetic resin substrate made of polyimide. The flat region 22 serving as a connection portion for one high-frequency circuit and the flat region 23 serving as a connection portion for the other high-frequency circuit are bent. 21 is connected.

A strip conductor 24 is formed in the center of one surface of the dielectric substrate 20 over the flat region 22, the bent region 21 and the flat region 23. This strip conductor 24
And ground conductors 25, 26
Are formed to constitute a microstrip line.
Each of the strip conductor 24 and the ground conductors 25 and 26 has a metal base film made of copper, and its surface is covered with a gold plating layer, and has a thickness of about 30 μm.

The portions of the strip conductor 24a and the ground conductor 25a that are most stressed when bending the bent area 21 are
In reference numeral 26a, the metal base layer is exposed by removing the gold plating layer.

Further, the ground conductor 25 in the bent area 21
The widths of a and 26a are partially narrower than the ground conductor width in the flat region.

The bending direction of the bending region is such that the microstrip line is on the outside as shown in FIG. However, considering the radius of curvature for bending the conductor, it is advantageous for the conductor to be on the outside because the radius of curvature of the conductor becomes larger.

It is needless to say that the present invention is similarly applied to other forms of strip lines such as slot lines and coupled lines in addition to the above embodiment.

[0025]

According to the present invention, it is possible to provide a connection line substrate which solves the problem of miniaturizing a circuit and reducing the loss.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of the present invention, in which FIG. 1A is a perspective view, FIG. 1B is a cross-sectional view taken along line BB of FIG. 1A, and FIG. It is.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is a perspective view showing a conventional example.

FIG. 5 is a perspective view showing another conventional example.

[Explanation of symbols]

 10: Dielectric substrate 11: Bent region 12, 13: Flat region 14: Surface (one surface) 15: Strip conductor 16: Ground conductor 17: Back surface (other surface)

Claims (4)

[Claims] 1. A dielectric substrate comprising a bent region, a first flat region and a second flat region extending on both sides of the bent region, and the first flat region on one surface of the dielectric substrate. And a strip conductor attached to the second flat region through the bent region, and a ground conductor wider than the strip conductor attached to the other surface of the dielectric substrate so as to face the strip conductor. Wherein the ground conductor is formed narrower in the bent region than in the first and second flat regions. 2. A dielectric substrate comprising a bent region, a first flat region and a second flat region extending on both sides of the bent region, and the first flat region on one surface of the dielectric substrate. And a strip conductor attached to the second flat region via the bent region, and a ground conductor attached to the one surface of the dielectric substrate adjacent to the strip conductor and wider than the strip conductor. Wherein the ground conductor has a first flat area and a second
A connection line substrate formed narrower than in a flat region. 3. The strip conductor on the first flat region and the second flat region has a base metal body and a gold plating layer formed on the surface of the base metal body, and the strip conductor on the bent region is a metal. 3. The connection line conductor according to claim 1, wherein the connection line conductor comprises only a base. 4. The connection line conductor according to claim 1, wherein the thickness of the bent region of the dielectric substrate is smaller than the thicknesses of the first flat region and the second flat region.