JPH11186458A - Connecting structure for transmission path for high frequency and wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connecting structure for transmission paths for high frequencies with high reliability, in which transmission paths for high frequencies formed on the both faces of a dielectric substrate are formed in a simple structure with a small transmission loss. SOLUTION: A connection structure of a co-planar line A and a co-planar line B is composed of central conductors 2 and 4 having terminal parts 2a and 4a, and ground layers 3 and 5 formed at the both sides and surrounding of the terminal parts which are formed on the both sides of a dielectric substrate 1. A discrete distance (y) between the ground layers 3 and 5 in the periphery of the terminal parts 2a and 4a of the co-planar line A and the co-planar line B is formed so as to be larger than a discrete distance (x) at the line parts, and the terminal parts 2a and 4a are arranged so as to be made in parallel like a plane, and so as to be overlapped on each other. Thus, the first co-planar line A and the second co-planar line B are electromagnetically connected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of interconnecting a semiconductor element, a passive component, and a connection terminal, and is capable of reducing deterioration of characteristics of a high-frequency signal and transmitting only a specific frequency. Connection structure for high-frequency transmission lines,
And a wiring board having such a connection structure.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor element package for hermetically sealing a semiconductor element, a semiconductor element is mounted in a cavity formed by a dielectric substrate and a lid made of a dielectric material and hermetically sealed. Stopped structures are known. In such a package, the frequency is 1G.
When a microwave signal of not less than Hz is handled, the input and output of a high-frequency signal to and from the semiconductor element are performed on the surface of the dielectric substrate 31 on which the semiconductor element 32 is mounted, as shown in FIG. Forming the transmission line 33 for
One end of the semiconductor element 3 is a wire bonding ribbon or the like.
2, a feed-through type semiconductor package in which the transmission line 33 is passed through the wall 34 and drawn out of the cavity 35 has been devised.

As a technique for transmitting a high-frequency signal in the vertical direction, as shown in FIG.
Similarly, a semiconductor device package in which a high-frequency transmission line 36 is similarly formed on the bottom surface of the semiconductor device and is connected to the high-frequency transmission line 33 in the cavity 35 via a through-hole conductor 37 is often used.

Further, as the dielectric substrate 31, alumina ceramics are most often used in terms of reliability of wiring formation, cost, and the like.

[0005]

However, FIG.
As shown in (a), when the transmission line 33 passes through the wall 34, since the wall passing portion is converted from the microstrip line to the strip line, it is necessary to narrow the signal line width. As a result, there is a problem that reflection loss and radiation loss are apt to occur in the passing portion, so that the characteristics of the high-frequency signal are likely to deteriorate.

On the other hand, in the package of FIG. 5 (b), although the transmission line does not pass through the wall 34, the signal characteristic deterioration is small, but conventionally used alumina ceramic is used as the dielectric substrate 31. In some cases,
When the operating frequency of the signal to be transmitted is 10 GHz or higher, the transmission loss in the through-hole conductor increases rapidly, and it has been difficult to transmit the signal in the high-frequency region without characteristic deterioration.

Accordingly, the present invention provides a high-reliability high-frequency transmission line connection structure in which a high-frequency transmission line formed on both surfaces of a dielectric substrate has a small transmission loss and a simplified structure and can be miniaturized. It is another object of the present invention to provide a wiring board using the connection structure of the high-frequency transmission line.

[0008]

Means for Solving the Problems As a result of the study on the above object, the present inventors have formed a central conductor and a coplanar line composed of a ground layer on both surfaces of a dielectric substrate, respectively. By arranging them at a specific position and electromagnetically coupling both lines, it has been found that a connection structure with a small transmission loss is obtained, and the present invention has been accomplished.

That is, a connection structure of a high-frequency transmission line according to the present invention comprises a first center conductor formed on one surface of a dielectric substrate and having a termination, and first ground layers formed on both sides thereof. A second coaxial conductor formed on the other surface of the dielectric substrate and having a termination, and a second ground layer formed on both sides of the second coaxial conductor. And a coplanar line, wherein the first coplanar line and the second coplanar line are formed so that the separation distance from the ground layer on both sides near the end portion of each central conductor is larger than other line portions. In addition, the first central conductor and the second central conductor are arranged so that their end portions are parallel and partially overlap with each other when viewed in a plan view, so that the first coplanar line and the second Coplay A line is characterized in that the allowed electromagnetic coupling.

Further, the wiring board of the present invention comprises a dielectric substrate, an electric element provided on one surface of the dielectric substrate, and one end formed on one surface of the dielectric substrate and having one end connected to the electric element. A first coplanar line that is electrically connected and includes a first central conductor having a terminal portion and first ground layers formed on both sides thereof; and a first coplanar line formed on the other surface of the dielectric substrate. And a second coplanar line composed of a second center conductor having a termination portion and second ground layers formed on both sides of the second center conductor, and wherein the first coplanar line and the second coplanar line are provided. The distance between the center layer and the ground layer on both sides near the end of each center conductor in the line is formed so as to be larger than the other line portions, and the first center conductor and the second center conductor are formed in a plane. In terms of each other It arranged such termination overlap parallel and partially and said first coplanar line and the second coplanar line is characterized in that the allowed electromagnetic coupling.

In the above, it is desirable that a signal having a frequency of 1 GHz or more is transmitted to the coplanar line.

[0012]

According to the present invention, a first coplanar line is formed on one surface of a dielectric substrate and a second coplanar line is formed on the other surface, and both are opposed to each other via a dielectric substrate under specific conditions. By performing electromagnetic coupling, signals can be transmitted with good transmission characteristics without being affected by transmission loss due to through-hole conductors, via-hole conductors, and the like.

Accordingly, for example, in a wiring board such as a package for a semiconductor element, a first coplanar line is formed on a semiconductor element mounting surface, a second coplanar line is formed on a bottom surface, and both are electromagnetically coupled. It is possible to suppress the occurrence of transmission loss of a high-frequency signal and provide a highly reliable wiring board.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A connection structure of a high-frequency transmission line according to the present invention will be described with reference to FIG. 1A is a diagram showing a conductor pattern on the surface of a dielectric substrate, and FIG.
FIG. 3A is a cross-sectional view taken along line AA, and FIG. 3C is a diagram illustrating a conductor pattern on the back surface of the dielectric substrate. According to FIG. 1, on one surface of a dielectric substrate 1, a first central conductor 2 having a termination 2a and a first ground layer 3 formed on both sides thereof and around the termination 2a. A first coplanar line A is formed. On the other hand, on the other surface of the dielectric substrate 1, a second center conductor 4 also having a termination portion 4a is provided.
A second coplanar line B composed of a second ground layer 5 formed on both sides and the periphery thereof is formed.

In the coplanar line A, the center conductor 2
On both sides of the line, with a spacing x in the line section,
The ground layer 3 is formed on both sides near the terminal end 2a of the center conductor 2 so that the separation distance y is greater than the distance x between the line portions. The distance between the center conductor 2 and the ground layer 3 is
Necessary for matching characteristic impedance. For example, when a dielectric substrate having a dielectric constant of 5.5 is used, x
Is designed to be 0.05 mm and y is designed to be 0.15 mm. If the relationship between x and y at this time is x = y or x> y, abrupt characteristic impedance mismatching occurs at the terminating end, causing reflection and causing deterioration of transmission characteristics.

On the other hand, also in the coplanar line B, the center conductor 4, the terminal 4a, and the ground layer 5 have the same terminal structure as the coplanar line A.

As shown in FIGS. 1A, 1B and 1C, the coplanar lines A and B are connected to the terminal 2a of the first central conductor 2 via the dielectric substrate 1. The end portion 4a of the second center conductor 4 is parallel to each other when viewed in plan,
In addition, they are arranged so that their end portions overlap each other. At this time, the length z of the overlapping portion is designed to be a length corresponding to １ ／ wavelength of the transmission signal wavelength λ, so that the coplanar line A and the coplanar line B are electromagnetically coupled in the transmission frequency region. be able to.

In the connection structure of the present invention, the first
The coplanar line A and the second coplanar line B of
As a result of the structure in which the dielectric substrate 1 is interposed, each of the first coplanar line A and the second coplanar line B is a coplanar line with ground. Further, it is desirable that the ground layer 3 in the first coplanar line A and the ground layer 5 in the second coplanar line B are electrically connected to each other by, for example, a through-hole conductor 6 so as to have the same potential. In the ground layer around the termination,
It is desirable to form a plurality of through-hole conductors 7 at intervals less than １ ／ wavelength of the wavelength λ of the transmission signal to electromagnetically surround the electromagnetic coupling portion.

In the connection structure according to the present invention,
The dielectric material constituting the dielectric substrate has a dielectric constant of 15
The following ceramics, glass ceramics, ceramic metal composite materials, glass organic resin composite materials, and the like are desirable. Among them, ceramics, glass ceramics, ceramic metal composite materials, and glass organic resin composite materials having a dielectric constant of 10 or less are particularly preferable. desirable.

Further, conductors forming the coplanar lines A and B include high melting point metals such as W and Mo, gold, silver, copper, and the like.
It can be formed of various conductor materials which have been conventionally used such as aluminum, and among them, low-resistance conductors such as gold, silver, copper, and aluminum are preferably used.

Next, a semiconductor device package will be described as an example of a wiring board to which the above-described connection structure for high-frequency transmission lines is applied. 2A is a cross-sectional view for explaining the structure, FIG. 2B is a conductor pattern on a semiconductor element mounting surface, and FIG. 2C is a bottom conductor pattern.
According to FIG. 2, the semiconductor element package 10 has a cavity 13 formed by a dielectric substrate 11 and a lid 12, and a semiconductor element 14 such as an MMIC or MIC is mounted in the cavity 13. .

According to the present invention, the center conductor 15 and the ground layer 16 are formed on the surface of the dielectric substrate 11 in the cavity 13 of the semiconductor element package as a line for transmitting a signal to the semiconductor element. A first coplanar line A is formed. One end of the first coplanar line A is connected to the semiconductor element 14 with a ribbon, a wire,
They are electrically connected by TAB (Tape Automated Bonding) or the like. The other end of the first coplanar line A forms a terminating portion 15 a on the surface of the dielectric substrate 11 in the cavity 13.

Similarly, a second coplanar line B including a center conductor 17 and a ground layer 18 is formed on the bottom surface of the dielectric substrate 11 outside the cavity 13 of the dielectric substrate. One end of the second coplanar line B forms a connection portion to the external electric circuit board of the package, the other end forms a terminal portion 17a, and the terminal portion 15a of the center conductor 15 in the first coplanar line A. 1 and the structure shown in FIG. 1, the first coplanar line A and the second coplanar line B are electromagnetically coupled.

As a result, it is possible to connect a series from the semiconductor element 14 to the second coplanar line B via the first coplanar line A, and to pass through a conventional through-hole conductor or wall between these connections. As a result, the transmission loss of the transmission signal can be reduced.

The lid 12 is made of a material that can prevent the electromagnetic waves from the cavity from leaking outside.
Ceramics, ceramic metal composite materials, glass ceramics and the like can be used.

In the semiconductor device package shown in FIG. 2, the power supply signal line (not shown) for supplying power to the semiconductor device 14 is provided in the cavity 13 in addition to the semi-first coplanar line A. ) Is formed, and the other end of the power supply signal line is connected to the dielectric substrate 1 through a through-hole conductor.
1 to the lower surface.

In FIG. 2, according to the semiconductor device package, instead of forming the cavity 13 by the dielectric substrate 11 and the lid 12, the semiconductor device 14 mounted on the surface of the dielectric substrate 11 is sealed. It is also possible to seal with resin.

Also, as an example of the wiring board, a semiconductor element package in which the semiconductor element is connected to the first coplanar line is illustrated. In addition, the semiconductor element is mounted on the front and back surfaces of the dielectric substrate. They can also be connected by electromagnetic coupling of the first coplanar line and the second coplanar line to achieve modularization.

The element connected to the coplanar line is not limited to a semiconductor element, but can be connected to an optical waveguide, a superconducting element, an antenna element, or the like.

FIG. 3 shows one means for evaluating the characteristics of the connection structure of the high-frequency transmission line of FIG. 1 for evaluating the transmission characteristics of a semiconductor device package. FIG. 3B is a pattern diagram of the surface of the dielectric substrate (the surface on which the semiconductor element is mounted), and FIG. As shown in this pattern diagram, two end portions 19 are provided on the front side.
a first coplanar line A composed of a center conductor 19 having a, a and 19b and a ground layer 20;
End portion 19 of center conductor 19 in coplanar line A of FIG.
a, 19b, and the center conductors 21, 2 electromagnetically coupled to
1 ′, two second coplanar lines B and B ′ including the ground layer 22 were formed, and the transmission characteristics of the two second coplanar lines B and B ′ on the back side were evaluated.

In this evaluation, the dielectric substrate was made to have a dielectric constant of 5.6 and a dielectric loss of 30.0 × 10 ⁻⁴ (measurement frequency 60
GHz), a center conductor and a ground layer were formed by copper metallization, and the surface thereof was plated with gold.

The dimensions of each coplanar line in FIG. 3 are as follows: the signal line width a is 110 μm, the terminal length b is 1.0 mm, the distance x between the center conductor of the line portion and the ground layer is 90 μm, The distance y from the ground layer near the terminal end is 400 μm, and the overlap length z is 0.8
mm.

Further, through-hole conductors (not shown) are formed at intervals of 0.5 mm in the ground layers 20 and 22 around the electromagnetic coupling portion and on both sides of the signal line, so that the first and second ground layers are electrically connected. Connected. The transmission characteristics of the wiring board for measurement were measured by a network analyzer. FIG. 4 shows the result at this time.

At this time, the transmission characteristics at 40 GHz were excellent, showing excellent transmission characteristics of S1 at -19.5 dB and S21 at -0.9 dB.

Next, the conventional semiconductor device package shown in FIG. 5 was similarly evaluated. In this assessment,
As a dielectric substrate, a dielectric constant of 9.8 and a dielectric loss of 18.0 ×
Using a dielectric material of 10 ^-4 (measuring frequency 60 GHz),
200μm diameter between transmission lines formed on the top and bottom
The semiconductor devices connected by through-hole conductors made of tungsten conductors were similarly measured by a network analyzer, and the results are shown in FIG. According to the results of FIG. 6, when the transmission line is connected by the through-hole conductor, the frequency is 20
S11: -10 dB or more, S21: -30 at GHz or more
Since it is less than dB, it was found that it was impossible to transmit a high-frequency signal to the semiconductor element.

[0036]

As described above in detail, according to the connection structure of a high-frequency transmission line of the present invention, it is possible to connect the high-frequency transmission lines provided on the front and back of the dielectric substrate with less characteristic deterioration. Thus, in a wiring substrate such as a semiconductor element package or a module substrate, the reliability of signal transmission in a wiring substrate that handles high-frequency signals of 1 GHz or more can be improved.

[Brief description of the drawings]

1A and 1B are diagrams for explaining a connection structure of a high-frequency transmission line according to the present invention, wherein FIG. 1A is a diagram illustrating a conductor pattern on a surface thereof, and FIG. 1B is a cross-sectional view taken along line AA in FIG. ,
(C) is a diagram showing a conductor pattern on the bottom surface.

FIGS. 2A and 2B are diagrams for explaining a structure of a semiconductor element package as an example of a wiring board using the connection structure of a high-frequency transmission line of the present invention, wherein FIG. 2A is a cross-sectional view, and FIG. (C) is a conductor pattern diagram on the bottom surface.

3 is a diagram for explaining a wiring board for evaluating characteristics of a connection structure of the high-frequency transmission line of FIG. 1,
(A) is a pattern diagram of a dielectric substrate surface (semiconductor element mounting surface), and (b) is a pattern diagram of a back surface.

FIG. 4 is a diagram showing transmission characteristics of the wiring board according to the present invention based on FIG. 3;

5 (a) and 5 (b) are cross-sectional views for explaining the structure of a conventional semiconductor device package.

FIG. 6 is a diagram illustrating transmission characteristics in the package of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Dielectric board 2 ... 1st center conductor 2a, 4a ... Termination part 3 ... 1st ground layer 4 ... 2nd center conductor 5 ... 2nd ground layer A: first coplanar line B: second coplanar line

Claims (4)

[Claims] 1. A first coplanar line formed on one surface of a dielectric substrate and having a first central conductor having a terminal portion, and first ground layers formed on both sides of the first central conductor. A connection structure for connecting a second center conductor formed on the other surface of the body substrate and having a termination portion, and a second coplanar line including second ground layers formed on both sides of the second center conductor, In the first coplanar line and the second coplanar line, the distance from the ground layer on both sides near the end of each central conductor is formed to be larger than the other line portions, and the first central conductor is formed. And the second center conductor are arranged so that their end portions are parallel and partly overlapped with each other when viewed in a plane, and the first coplanar line and the second coplanar line are electromagnetically coupled. Features Connection structure of the high frequency transmission line. 2. The coplanar line has a frequency of 1 GHz.
The connection structure for a high-frequency transmission line according to claim 1, wherein the signal is transmitted. 3. A dielectric substrate, an electric element provided on one surface of the dielectric substrate, and one end formed on one surface of the dielectric substrate and electrically connected to the electric element at one end.
A first coplanar line including a first center conductor having a terminal portion and first ground layers formed on both sides thereof; and a second coplanar line formed on the other surface of the dielectric substrate and having a terminal portion. , And a second coplanar line including a second ground layer formed on both sides of the center conductor, and a termination of each center conductor in the first coplanar line and the second coplanar line. The distance between the ground layer and the ground layer on both sides in the vicinity of the portion is formed so as to be larger than the other line portions, and the first center conductor and the second center conductor are mutually terminated at a planar view. Wherein the first coplanar line and the second coplanar line are electromagnetically coupled to each other so as to be parallel and partially overlapped with each other. 4. The coplanar line has a frequency of 1 GHz.
The wiring board according to claim 3, wherein the signal is transmitted.