JP3470053B2 - Connection structure for high frequency components - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component such as a semiconductor element in the information communication field and the semiconductor field, and a high-frequency component such as a semiconductor device or a semiconductor package or a wiring board. Regarding the connection structure of high-frequency components used for interconnection in the propagation of high-frequency signals, particularly the connection structure of high-frequency components with improved high-frequency electrical characteristics at the connection portion when connecting the high-frequency components by a so-called flip-chip mounting method About. 2. Description of the Related Art Conventionally, as a structure in which a semiconductor element as a high-frequency component is connected to a high-frequency wiring board, which is also a high-frequency component, by a flip-chip mounting method, as shown in a sectional view in FIG. There is a connection structure. In FIG. 4, 1 is a high-frequency semiconductor element, and 6 is a high-frequency wiring board. The high-frequency semiconductor element 1 has a ground conductor 3 formed on an upper surface of a base 2 and a line conductor 4 for transmitting a high-frequency signal formed on the lower surface. Pads 5a and 5b are provided. On the other hand, the high-frequency wiring board 6 has a plurality of ground conductors 8 on the inside and underside of a base 7 formed by laminating a plurality of dielectric layers 7a, 7b and 7c.
a, 8b, and 8c are formed on the upper surface with two line conductors 9a and 9b, and connection pads at both ends of the line conductor 4 of the high-frequency semiconductor element 1 are provided at one end of each of the line conductors 9a and 9b. Connection pads 10a and 10b, which are high frequency input / output sections corresponding to 5a and 5b, are provided. The high-frequency semiconductor element 1 is placed on the upper surface of the high-frequency wiring board 6 with these line conductors 4.9a, 9a.
b, the connection pads 5a and 5b and 10a and 10b, which are input / output sections for high frequency, are placed facing each other, and a conductive connecting member is provided between each of the connection pads 5a and 5b and the connection pad 10a and 10b. For example, they are connected by metal bumps 11a and 11b. However, in this conventional connection structure for high-frequency components, the line conductor 4 of the high-frequency semiconductor element 1 faces a plurality of ground conductors 8 a to 8 c of the high-frequency wiring board 6. Therefore, a high-frequency signal propagating through the line conductor 4 of the high-frequency semiconductor element 1 has an electric field distribution with respect to the ground conductors 8a to 8c. As a result, the characteristic impedance has a value greatly different from the design value, and reflection or radiation loss of a high-frequency signal due to electrical discontinuity occurs at the connection portion,
There is a problem that the electrical characteristics are deteriorated. As a configuration for reducing such deterioration of the electric characteristics, for example, Japanese Patent Application Laid-Open No. 9-260426, entitled "Mounting board, mounting method and semiconductor device" shows a sectional view similar to FIG. A connection structure for high-frequency components as shown in FIG. In FIG. 5, the same parts as those in FIG. 4 are denoted by the same reference numerals. In this configuration, with respect to the base 7 of the high-frequency wiring board 6, it is assumed that the dielectric layer 7 c is not formed in a portion facing the line conductor 4 of the high-frequency semiconductor element 1, and the concave portion 12 in which no dielectric is formed is formed in that portion. Provided. According to such a configuration, the electric field distribution from the line conductor 4 of the high-frequency semiconductor element 1 to the ground conductor 8c of the high-frequency wiring board 6 is reduced. The characteristic impedance of the propagated high-frequency signal does not greatly differ from the designed value, and matching can be performed while maintaining the characteristic impedance at the designed value. However, in the connection structure for high-frequency components proposed in Japanese Patent Application Laid-Open No. 9-260426, although it is possible to maintain the characteristic impedance of the line conductor, the recess 12 is formed with high precision. Because of the necessity, there is a problem in that the production becomes difficult and the number of production steps is increased. The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to improve the electrical characteristics of a high-frequency signal in a connection structure of high-frequency components by flip-chip mounting, An object of the present invention is to provide a connection structure for a high-frequency component that can stably obtain a connection portion having good electric characteristics without difficulty in manufacturing. According to the present invention, there is provided a connection structure for a high frequency component, comprising: a ground conductor on an upper surface of a base; A first high-frequency component on which a conductor is formed, a plurality of ground conductors are formed on the lower surface side of the base, and a line conductor for high-frequency signal transmission having a connection portion corresponding to the connection portion at the top is formed on the upper surface side. A second high-frequency component, with the connection portions facing each other and electrically connected by a conductive connection member;
A conductor non-forming region is provided at least in a portion of the plurality of ground conductors formed on the second high-frequency component, which is opposed to a line conductor of the first high-frequency component, of a ground conductor on the uppermost surface side. It is assumed that. According to the connection structure of a high-frequency component of the present invention, in a connection structure in which a first high-frequency component is flip-chip mounted on a second high-frequency component, a plurality of ground conductors are connected. At least a ground conductor on the uppermost surface side of the second high-frequency component having no conductor is formed at a portion opposed to the line conductor of the first high-frequency component mounted on the upper surface and connected to the connection portions of the high-frequency signals. Because there is an area,
In the conventional connection structure in which the ground conductor is also formed at the portion of the second high-frequency component opposite to the line conductor of the first high-frequency component, the first high-frequency component is used in accordance with the law of least action starting from the vicinity of the connection portion. The electric field component from the line conductor toward the ground conductor of the second high-frequency component has an electric field distribution in which no electric field is generated in the non-conductor-formed region. In this case, if there is a ground conductor further below the distribution, the distribution is directed toward the ground conductor. However, since the distribution is directed only to a weaker component than the component directed toward the ground conductor of the first high-frequency component, The electric field distribution from the line conductor of the first high-frequency component approaches the designed electric field distribution as compared to the conventional connection structure. Thereby, compared to a case where a high-frequency signal propagating through the line conductor of the first high-frequency component has a strong electric field distribution to the ground conductor of the second high-frequency component as in the conventional connection structure, the electric connection is higher. High frequency signal reflection and radiation loss due to discontinuity can be reduced, and as a result, electrical characteristics can be improved, so that high frequency signals with good electrical characteristics can be connected. It becomes a connection structure of parts. Further, according to the connection structure for high-frequency components of the present invention, good electrical characteristics equivalent to or better than the connection structure for high-frequency components disclosed in Japanese Patent Application Laid-Open No. 9-260426 are obtained. In addition, since it is only necessary to provide a conductor-free region that does not require particularly high precision in a part of the plurality of ground conductors of the second high-frequency component, the second high-frequency component can be formed by a conventionally known manufacturing method. Can be easily manufactured, and a connection structure for high frequency components can be stably obtained with a connection structure having good electrical characteristics. According to the connection structure of the high-frequency component of the present invention, in addition to the conductor-free area provided in the ground conductor of the second high-frequency component, the ground conductor on the uppermost surface side and a plurality of ground conductors located thereunder In the same manner, the electric field component from the line conductor of the first high-frequency component to the ground conductor of the second high-frequency component is further reduced, so that the electric field distribution of the line conductor of the first high-frequency component Becomes closer to the designed electric field distribution, and the reflection and radiation loss of the high-frequency signal due to the electrical discontinuity can be more effectively reduced. The conductor-free area provided on the ground conductor of the second high-frequency component as described above is formed by the first opposing area.
It is sufficient if it is provided at a portion corresponding to the line conductor of the high-frequency component, but if the portion is included, for example, it is assumed that it covers a portion facing almost the entire surface of the first high-frequency component. It may be provided. In the case where the conductor-free region is provided over a wider area including the portion facing the line conductor of the first high-frequency component, the line conductor faces the line conductor of the first high-frequency component. The electric field component directed to the ground conductor of the second high-frequency component, which has been generated, hardly occurs. Therefore, the electric field distribution of the line conductor of the first high-frequency component more effectively approaches the designed electric field distribution. The reflection and radiation loss of the high-frequency signal due to the electrical discontinuity can be further reduced. Hereinafter, the connection structure of the high frequency component of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an example of a connection structure of a high-frequency component according to the present invention. In FIG. 1, reference numeral 21 denotes a high-frequency semiconductor element as a first high-frequency component, and reference numeral 26 denotes a high-frequency wiring board as a second high-frequency component. High frequency semiconductor element 21
A ground conductor 23 is formed on the upper surface side of the base 22, in this example, a ground conductor 23 is formed on the upper surface, and a line conductor 24 for transmitting a high-frequency signal is formed on the lower surface side, in this example, on the lower surface. Connection pads 25a and 25b, which are signal connection portions (high-frequency input / output portions), are provided. The ground conductor 23 and the line conductor 24
As long as the ground conductor 23 and the line conductor 24 function as a ground conductor and a line conductor for transmitting a high-frequency signal by the ground conductor 23 and the line conductor 24, a part of each of them is a so-called inner layer formed inside the base 22. May be used. Further, a plurality of line conductors 24 may be formed, and a coplanar line structure in which the same surface ground conductor is provided on both sides may be used. The ground conductor 23 is usually formed on substantially the entire back surface of the base 22. However, if the ground conductor 23 functions as a ground conductor for transmitting high-frequency signals by the line conductor 24, the ground conductor 23 may be formed on the line conductor 24. What is necessary is just to form only in the required part corresponding. On the other hand, the high-frequency wiring board 26 has a plurality of grounding conductors 28a, 28b on the lower surface side of the base 27 formed by laminating a plurality of dielectric layers 27a, 27b, 27c, for example.
Two line conductors 29a and 29b are formed on the upper surface side, in this example, on the upper surface side, and one end of each of the line conductors 29a and 29b is provided with the line conductor 24 of the high-frequency semiconductor element 21 on the upper surface side. Connection pads that are high-frequency signal connection parts (high-frequency input / output parts) corresponding to the connection pads 25a and 25b at both ends
30a and 30b are provided. The line conductors 29a and 29b are not disposed at positions facing the line conductor 24 of the high-frequency semiconductor element 21, and the line conductors 24 are connected to the ground conductors 28a to 28c of the high-frequency wiring board 26. It is formed so as to face. Also,
The line conductors 29a and 29b may also be partially formed inside the base body 27 to form a so-called inner layer.
And a coplanar line structure in which the same plane ground conductor is provided on both sides. The ground conductors 28a to 28c are usually
Formed on substantially the entire back side of the line conductors 29a and 29b.
As long as the conductor functions as a ground conductor for transmitting a high-frequency signal, it may be formed only in a necessary portion corresponding to the line conductors 29a and 29b. The high-frequency semiconductor element 21 is mounted on the upper surface of the high-frequency wiring board 26 with the connection pads 25a, 25b and 30a, 30b of the line conductors 24, 29a, 29b facing each other. The connection pads 25a and 25b and the connection pads 30a and 30b are connected by a conductive connection member, for example, metal bumps 31a and 31b. In order to obtain a good connection state at the connection portion, the bases 22 and 27 on both sides of the connection pads 25a, 25b, 30a and 30b at the tips of the respective line conductors 24, 29a and 29b.
Ground pads are provided on the surface of the
The electrical connection may be made by the same metal bump as that of a.31b. Reference numeral 32 denotes a ground conductor on at least the uppermost side of the plurality of ground conductors 28a to 28c of the high-frequency wiring board 26, in this example, a portion of the ground conductor 28c facing the line conductor 24 of the high-frequency semiconductor element 21. Is a conductor non-formation area provided in the above. According to the connection structure for high-frequency components of the present invention, at least the uppermost ground conductor of the plurality of ground conductors 28a to 28c of the high-frequency wiring board 26, which is the second high-frequency component, is used. By providing the conductor non-forming region 32 in the connection structure 28c, the connection pads 25a, 25b,
From the line conductor 24 of the high-frequency semiconductor element 21 to the high-frequency wiring board in accordance with the law of least action, including the vicinity of 30a and 30b.
The electric field component directed toward the ground conductor 28c on the uppermost surface side of 26 does not generate an electric field in the conductor non-formed region 32, and only a component that is weaker than the component directed toward the ground conductor 23 of the high frequency semiconductor element 21 is directed. As a result, the electric field distribution from the line conductor 24 of the high-frequency semiconductor element 21 approaches the designed electric field distribution. Thereby, reflection and radiation loss of a high-frequency signal due to electrical discontinuity can be reduced, electrical characteristics can be improved, and connection of a high-frequency signal having good electrical characteristics can be performed. . FIG. 2 is a sectional view similar to FIG. 1 showing another embodiment of the connection structure for high frequency components of the present invention. In FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, 21 is a high-frequency semiconductor element, 22 is a base,
23 is a ground conductor, 24 is a line conductor, and 25a and 25b are connection pads. 26 is a high frequency wiring board, 27 is a base (27a
To 27b are dielectric layers), 28a to 28c are a plurality of ground conductors, 29
a and 29b are line conductors, 30a and 30b are connection pads,
31a and 31b are metal bumps. In this example, as in the example of FIG. 1, the line conductor of the high-frequency semiconductor element 21 of the uppermost ground conductor 28c of the plurality of ground conductors 28a to 28c of the high-frequency wiring board 26 is used.
A conductor non-formation region 32a is provided at a portion facing the conductor 24, and a conductor non-formation region 32b is further provided at a portion of the ground conductor 28b located on the lower surface side thereof facing the line conductor 24. According to the connection structure for high-frequency components of the present invention, the electric field component from the line conductor 24 of the high-frequency semiconductor element 21 to the ground conductors 28a to 28c of the high-frequency wiring board 26 is further reduced. In addition, the electric field distribution of the line conductor 24 of the high-frequency semiconductor element 21 becomes closer to the designed electric field distribution, and the reflection and radiation loss of the high-frequency signal due to the electrical discontinuity can be more effectively reduced. Next, a specific example of the connection structure of the high frequency component of the present invention will be described. First, a metal conductor film covering almost the entire upper surface was formed as a ground conductor on a substrate made of a dielectric substrate having a relative dielectric constant of 9.6 and a thickness of 100 μm. In addition, the line conductor of the microstrip line is placed on the lower surface of the base with the line width.
It was formed to a thickness of 95 μm, and a connection pad was connected to the tip. Thus, a first high-frequency component was manufactured. On the other hand, a metal conductor film was formed as a plurality of ground conductors on the lower surface and the inner layer of a substrate formed by laminating dielectric layers each having a relative dielectric constant of 8.8 and a thickness of 200 μm per layer. Further, a line conductor of a microstrip line was formed on the upper surface of the base, and connected to a connection pad formed at a position corresponding to the connection pad of the first high-frequency component. Here, among the ground conductors in the inner layer, the ground conductor on the top surface side includes:
A conductor non-forming region having a shape corresponding to the line conductor was provided in a portion of the first high-frequency component facing the line conductor. Thus, a second high-frequency component was manufactured. The first high-frequency component and the second
1 is connected by a flip-chip mounting method using metal bumps having a height h (h = 10, 30, 50 μm) with the connection pads facing each other.
The sample A which is the connection structure of the high frequency component of the present invention shown in FIG. Next, as a second high-frequency component, a conductor-free region having the same shape and dimensions is provided also on the ground conductor located on the lower surface side of the ground conductor provided with the inner-layer conductor-free region as described above, The other components were manufactured in the same manner as the sample A, whereby the sample B having the connection structure of the high-frequency component of the present invention shown in FIG. 2 was manufactured. As a comparative example, the same procedure as in the above-mentioned samples A and B was carried out except that no conductor-free region was formed in the ground conductor of the second high-frequency component.
The sample C having the connection structure of the conventional high frequency component shown in FIG. Then, the samples A, B, and C were subjected to electromagnetic field analysis to determine in a plane perpendicular to the propagation direction of the high-frequency signal in the laminated portion where the first high-frequency component and the second high-frequency component overlapped. The characteristic impedance in the cross section of was extracted. FIG. 3 shows the results of extracting these characteristic impedances. FIG. 3 shows a sample A.
It is a diagram which shows the characteristic impedance of sample B and sample C, and a horizontal axis | shaft shows the number of dielectric layers in the ground conductor in which the conductor non-forming area | region is provided from the upper surface in the 2nd high frequency component. I have. That is, the number of layers 0 corresponds to sample C, the number of layers 1 corresponds to sample A, and the number of layers 2 corresponds to sample B. The vertical axis represents characteristic impedance (unit: Ω).
The characteristic curves indicated by the solid line (h10), the broken line (h30), and the dotted line (h50) are obtained when the bump height h is 10 μm, 30 μm, and 50 μm in each of the samples A, B, and C. The change of the characteristic impedance according to each bump height is shown. As can be seen from the results, the sample A and the sample B having the connection structure of the high-frequency component according to the present invention have characteristic impedances at design values, as compared with the sample C having the connection structure of the conventional high-frequency component. Since it has a value close to a certain 50Ω, impedance matching is performed, and excellent high-frequency electrical characteristics are obtained. Thus, according to the connection structure for high-frequency components of the present invention, reflection and radiation loss of high-frequency signals due to electrical discontinuity can be reduced as compared with the conventional connection structure for high-frequency components. As a result, it was confirmed that electrical characteristics could be improved and high-frequency signals having good electrical characteristics could be connected. It should be noted that the above is only an example of the embodiment of the present invention, and the present invention is not limited to the embodiment. Various changes and improvements may be made without departing from the gist of the present invention. No problem. For example, in the above example, an example was shown in which metal bumps were used as the conductive connection members. However, if the conductive connection members electrically connect the high-frequency input / output units to each other via the conductors, the conductive connection members may include pads and the like. Also, it may be a ball or a pillar. According to the connection structure of the high-frequency component of the present invention, in the connection structure in which the first high-frequency component is flip-chip mounted on the second high-frequency component, a connection structure having a plurality of ground conductors is provided. Since at least the uppermost ground conductor of the second high-frequency component has a conductor non-forming region at a position facing the line conductor of the first high-frequency component, the second conductor has a region from the line conductor of the first high-frequency component. The electric field component directed toward the ground conductor of the second high-frequency component becomes an electric field distribution in which no electric field is generated in the conductor-free area, or the distribution is a component that is weaker than the component directed toward the ground conductor of the first high-frequency component. Therefore, the electric field distribution from the line conductor of the first high-frequency component approaches the designed electric field distribution. Thereby, reflection and radiation loss of the high-frequency signal due to the electrical discontinuity can be reduced, and the electrical characteristics can be improved. Therefore, the connection of the high-frequency signal having good electrical characteristics can be performed. it can. Further, according to the connection structure of the high-frequency component of the present invention, it is only necessary to provide a conductor-free region which does not particularly require high precision in a part of the plurality of ground conductors of the second high-frequency component. The second high-frequency component can be easily manufactured by a conventionally known manufacturing method, and a connection structure having good electric characteristics can be stably obtained. As described above, according to the present invention, it is possible to improve the electrical characteristics of the high-frequency signal in the connection structure of the high-frequency components by flip-chip mounting, and to achieve good electrical characteristics without difficulty in manufacturing. The connection structure of the high-frequency component, which can stably obtain the connection part of the above, can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of an embodiment of a connection structure for high frequency components of the present invention. FIG. 2 is a cross-sectional view showing another example of the embodiment of the connection structure for high-frequency components of the present invention. FIG. 3 is a diagram showing a change in characteristic impedance in a connection structure of a high-frequency component. FIG. 4 is a cross-sectional view showing an example of a conventional connection structure for high frequency components. FIG. 5 is a cross-sectional view showing another example of a conventional connection structure for high frequency components. [Description of Signs] 21 ···················································································· ..Line conductors 25a, 25b connection pad (connection part) 26 wiring board for high frequency (second high frequency component) 27 bases 28a to 28c -Ground conductors 29a, 29b-Line conductors 30a, 30b-Connection pads (connection parts) 31-Metal bumps (conductive connection members) 32, 32a, 32b-Conductors not formed region

Claims (1)

(1) A first high-frequency device in which a ground conductor is formed on an upper surface of a base, and a line conductor for transmitting a high-frequency signal having a connection portion for a high-frequency signal at a front end is formed on a lower surface of the base. A plurality of grounding conductors on the lower surface side of the base, and a second high-frequency component on which a line conductor for high-frequency signal transmission having a connection portion corresponding to the connection portion at the tip on the upper surface side is formed. The connection portions are opposed to each other to be electrically connected by a conductive connection member, and at least the topmost ground conductor of the first high-frequency ground conductor among the plurality of ground conductors formed on the second high-frequency component A connection structure for a high-frequency component, wherein a conductor-free area is provided in a part of the component facing a line conductor.