JP2000100994A - High-frequency package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency package excellent in high-frequency characteristics by a method wherein it is protected against characteristic impedance mismatching and deterioration in transmission characteristics. SOLUTION: A signal line 1 is composed of a micro strip line structure that comprises a package inner part and a package outer part, a strip line structure that is a hermetically sealed part, and an embedded microstrip line structure that is a tapered part which connects them together. Therefore, the tapered part can be prevented from causing characteristic impedance mismatching. Furthermore, the embedded microstrip line structure can be comparatively easily formed, so that a high-frequency package of this constitution can be lessened in manufacturing man-hours and manufacturing cost. Moreover, the distance between the edge of a ground plane 6 and its connecting point connected to a conductor via 7 nearest to the edge of the ground plane 6 can be made nearly zero, so that a high-frequency package can be prevented from deteriorating in transmission characteristics of high-frequency signal due to circuitry structure of stub.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency package having a signal line for transmitting high-frequency signals such as microwaves and millimeter waves.

[0002]

2. Description of the Related Art In recent years, the operating speed of semiconductor devices has been increased,
With the increase in the frequency, a high-frequency package having a signal line for efficiently transmitting a high-frequency signal of several GHz to several tens GHz or more is required.

As a conventional high-frequency package, for example, as shown in FIG. 5, a ceramic or the like in which a metal layer 14 serving as a ground plane is formed on a lower surface and a signal line 11 for transmitting a high-frequency signal is formed on an upper surface. RF package 10 comprising an insulating substrate 12 and a cover member 8 made of metal or the like for hermetically sealing a semiconductor element 10 such as a semiconductor integrated circuit and an insulating frame member 13 insulating the signal line 11.
0 is known. The signal line 11 is led from the inside to the outside of the package constituted by the insulating substrate 12, the insulating frame member 13, and the lid member 8, and is hermetically sealed by an airtight sealing portion sandwiched between the insulating substrate 12 and the insulating frame member 13. Is sealed. The signal line 11 is connected to an electrode of the semiconductor element 10 by a connection line 9 made of aluminum or gold.

The above-described high-frequency package 100
The ground plane 15 provided on both sides of the signal line 11 and the signal line 1 are provided, for example, as shown in FIG.
A ground plane 16 is provided between the upper insulating frame member 13a and the lower insulating frame member 13b. Each of the ground planes 14, 15 and 16 is electrically connected by a conductor via 17.

[0005]

In the above-mentioned conventional high-frequency package 100, the signal line 11 electrically connects the inside and outside of the hermetically sealed package.
For this reason, the hermetically sealed portion is sandwiched between the insulating substrate 12 and the insulating frame member 13 and has the same thickness and dielectric constant to form a strip line structure. on the other hand,
The inner and outer portions of the package have a microstrip line structure or a grounded coplanar structure sandwiched between an insulating substrate 12 having a ground plane 14 formed on the lower surface and an upper space. If the line width of the signal line 11 is the same at all points, the characteristic impedance at the hermetically sealed portion becomes lower than the characteristic impedance at the inner and outer portions of the package. However, there is a problem that a reflection loss occurs due to the mismatch between the two.

Therefore, in the high-frequency package disclosed in Japanese Patent Publication No. 8-12887, for example, as shown in FIG. 7, the line width of the signal line 11b in the hermetically sealed portion is reduced by the signal width of the signal inside and outside the package. The width of the line 11a is made smaller than the line width to match the characteristic impedance of the hermetically sealed portion. Actually, reflection loss or the like occurs at a connection portion between the signal line 11a and the signal line 11b where the line width of the signal line rapidly changes.
It is preferable to provide a tapered portion 11c having a gradually changed line width between the signal line 11b and the signal line 11b.

However, in the high-frequency package disclosed in Japanese Patent Publication No. 8-12887, it has been found that the transmission characteristics of the signal line 11 deteriorate for high-frequency signals exceeding 20 GHz due to the following problems. .

(1) The characteristic impedance of the tapered portion 11c connecting the signal lines 11a on the inner and outer portions of the package and the signal line 11b on the hermetically sealed portion is not matched with the characteristic impedance of the signal lines 11a and 11b. Wake up. The tapered portion 11c is provided to reduce reflection loss and the like when the signal line 11a and the signal line 11b are directly connected. However, the characteristic impedance of the signal line 11 is determined such that the cross-sectional structure can be matched with the signal lines 11a and 11b, which are the main parts. Therefore, the characteristic impedance of the tapered portion 11c is relatively small in the hermetically sealed portion. And the signal line 1 becomes relatively large in the inner and outer parts of the package.
A mismatch occurs with the characteristic impedance of 1a and 11b.

(2) As shown in FIG. 8, ground planes 14 located above, on both sides, and below the signal line 11,
Conductor via 1 electrically connecting 15 and 16 respectively
The distance L between a connection point 16b between the ground plane 16 and the end 16a of the ground plane 16 is the signal line 11
The wavelength is １ ／ or more of the wavelength λ of the high frequency signal to be transmitted. In Japanese Patent Application Laid-Open No. 9-46008, when a distance between an end of a ground plane and a conductor via closest to the end is formed to be less than 1/4 of a wavelength λ of a high-frequency signal transmitted to a signal line, a high-frequency signal is generated. It is disclosed that transmission can be performed efficiently. However, reducing the distance L shown in FIG. 8 as much as possible not only increases the manufacturing cost, but also leaves a certain distance L and deteriorates the transmission characteristics of the high-frequency signal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems (1) and (2). The present invention prevents mismatching of characteristic impedance and deterioration of transmission characteristics and has excellent high frequency characteristics. An object is to provide a high-frequency package.

[0011]

According to the high frequency package of the present invention, an insulating substrate having a metal layer on the lower surface, and an upper surface of the insulating substrate which is joined to the upper surface of the insulating substrate and mounted on the upper surface of the insulating substrate inside. Frame member having a space for accommodating the formed high-frequency circuit or semiconductor element, and formed on the upper surface of the insulating substrate from the inside to the outside of the insulating frame member, and a part is sandwiched between the insulating substrate and the insulating frame member Signal lines,
An upper surface of the insulating substrate, and a plurality of ground patterns provided on a surface layer or an inner layer of the insulating frame member, and a plurality of vias or through holes for electrically connecting the respective ground patterns of the plurality of ground patterns to each other. I have. The width of the ground pattern provided inside the insulating frame member above the signal line is substantially equal to the distance between a plurality of vias or through holes provided in the insulating frame member. Line and embedded microstrip line.

Here, the microstrip line has a structure in which a signal line 21 is provided on an upper surface of a dielectric 22 having a ground pattern 23 as a metal layer on the lower surface, for example, as shown in FIG. The line has a structure in which the signal line 21 and the ground patterns 23 and 24 are separated by a dielectric 22, as shown in FIG. 9B, for example. As shown, the structure has no ground pattern on one side of the strip line.

Since the width of the ground pattern provided inside the insulating frame member above the signal line is substantially equal to the distance between the plurality of vias or through holes, the inner and outer portions of the package having the microstrip line structure can be used. An embedded strip line structure portion is formed between the strip line structure and the hermetically sealed portion.
In the three types of structures of the microstrip line, the strip line, and the embedded microstrip line, the line widths of the signal lines having the same characteristic impedance are a microstrip line, an embedded microstrip line, and a strip line in descending order. For this reason, by forming a connection portion of the signal line having a line width between the line width of the signal line of the microstrip line structure portion and the line width of the signal line of the strip line structure portion in the embedded microstrip line structure portion. ,
It is possible to prevent the characteristic impedance from being mismatched at the connection portion of the signal line.

Further, since the above-mentioned embedded microstrip line structure can be formed relatively easily, a manufacturing process similar to the conventional one can be adopted.
The number of manufacturing steps and manufacturing costs can be reduced to the same level as in the past.

Furthermore, the distance from the end of the ground pattern provided inside the insulating frame member to the connection point with the via or through hole closest to this end can be made substantially zero. Therefore, it is possible to prevent the stub from deteriorating the transmission characteristics of the high-frequency signal.

As the insulating substrate and the insulating frame member, for example, ceramics such as alumina and mullite, glass ceramics, or resin-based materials such as Teflon-glass epoxy-polyimide can be used.

The lid member for hermetically sealing the high-frequency circuit or the semiconductor element is made of, for example, metal or the like.
And a space for accommodating a high-frequency circuit or a semiconductor element can be hermetically sealed. Further, the same insulating material as the insulating frame member may be used as the lid member.

The signal line is made of Cu, Mo-Mn, Cu-
It is formed by a method such as thick-film printing or thin-film formation or plating using W, Au, or the like, and the thickness and width thereof can be appropriately set according to the specifications of the high-frequency signal to be propagated and the high-frequency package. The metal layer, the ground pattern, and the vias or through holes are formed by the same method using the same material as the signal line.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a high frequency package according to an embodiment of the present invention. As shown in FIG. 2, the high-frequency package 20 has an insulating substrate 2 made of ceramic or the like on which a metal layer 4 serving as a ground plane is formed on a lower surface and a signal line 1 for transmitting a high-frequency signal is formed on an upper surface. A cover member 8 made of metal or the like for hermetically sealing a semiconductor element 10 such as a circuit is provided with an insulating frame member 3 for insulating the signal line 1. The signal line 1 is led out from the inside to the outside of the package formed by the insulating substrate 2, the insulating frame member 3, and the lid member 8, and is hermetically sealed by the hermetically sealed portion sandwiched between the insulating substrate 2 and the insulating frame member 3. Is sealed. The signal line 1 is connected to an electrode of the semiconductor element 10 by a connection line 9 made of aluminum or gold.

As shown in FIG. 1, high-frequency package 2
Reference numeral 0 denotes a ground plane 5 serving as a ground pattern provided on both sides of the signal line 1 to secure isolation from other signal lines (not shown), and an insulating frame member 3 a above the signal line 1 and a ground plane 5 below the lid member 8. And a ground plane 6 as a ground pattern provided between the insulating frame member 3b. Each of the ground planes 4, 5 and 6 is electrically connected by a conductor via 7.

As shown in FIG. 3, the signal line 1 includes a signal line 1a at an inner portion and an outer portion of the package, a signal line 1b at a hermetically sealed portion, and a signal line 1a and a signal line 1b.
And a tapered portion 1c connecting the two. The signal lines 1a on the inner and outer parts of the package constitute a microstrip line structure with a space at the top,
The signal line 1b in the hermetically sealed portion forms a strip line structure. For this reason, by changing the line widths of the signal lines 1a and 1b and the distances from the signal line 1 to the ground planes 4, 5, and 6, the characteristic impedance of the signal line 1a and the signal line 1b can be matched. Can be.

Further, since the tapered portion 1c connecting the signal line 1a and the signal line 1b has an embedded microstrip line structure in which no ground plane is provided on the upper portion, the characteristic impedance of the tapered portion 1c is hermetically sealed. It tends to be larger than the signal line 1b at the stop. However, since the line width gradually increases from the signal line 1b to the signal line 1a, the characteristic impedance of the tapered portion 1c can be reduced. That is, the characteristic impedance of the tapered portion 1c is
The characteristic impedance tends to increase due to the absence of the upper ground plane, and the characteristic impedance tends to decrease as the line width of the signal line gradually increases, thereby preventing characteristic impedance mismatch. can do.

As shown in FIG. 4, the width W of the upper ground plane 6 of the signal line 1b at the hermetically sealed portion is
The distance is substantially equal to the distance W7. Therefore, the distance from the end 6a of the ground plane 6 to the connection point 6b with the conductor via 7 closest to the end 6a can be made substantially zero.

In this embodiment, the signal lines 1a at the inner and outer portions of the package form a microstrip line structure with a space at the top, and the signal lines 1b at the hermetically sealed portion form a strip line structure. Yes,
The tapered portion 1c forms an embedded microstrip line structure in which a ground plane is not provided on the upper portion. The width W of the upper ground plane 6 of the signal line 1b in the hermetically sealed portion is equal to the distance W between the conductor vias 7.
It is almost equivalent to 7. Therefore, mismatch between the characteristic impedance of the tapered portion 1c and the characteristic impedance of the signal lines 1a and 1b can be prevented.

Further, in this embodiment, since the embedded microstrip line structure can be formed relatively easily, a manufacturing process similar to the conventional one can be employed, and the number of manufacturing steps and manufacturing costs can be reduced to the same level as the conventional one. Can be reduced.

Furthermore, in this embodiment, the distance from the end 6a of the ground plane 6 to the connection point 6b with the conductor via 7 closest to the end 6a can be made substantially zero. Therefore, it is possible to prevent the stub from deteriorating the transmission characteristics of the high-frequency signal.

In this embodiment, an example has been described in which the ground planes 4, 5, and 6 are electrically connected to each other via the conductor via 7. However, in the present invention, the respective ground patterns are electrically connected to each other through the through holes. May be connected.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a high-frequency package according to an embodiment of the present invention, and is an enlarged perspective view of a main part of FIG. 2;

FIG. 2 is a longitudinal sectional view showing a high-frequency package according to an embodiment of the present invention.

FIG. 3 is an enlarged plan view of a main part of FIG. 2;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a longitudinal sectional view showing a conventional high-frequency package.

FIG. 6 is an enlarged perspective view of a main part of FIG.

FIG. 7 is an enlarged plan view of a main part of FIG.

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a schematic cross-sectional view for explaining the structure of a signal line, where (A) shows a microstrip line,
(B) shows a strip line, and (C) shows an embedded microstrip line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Signal line 2 Insulating board 3 Insulating frame member 4 Ground plane (metal layer) 5, 6 Ground plane (ground pattern) 7 Conductor via 8 Lid member 10 Semiconductor element 20 High frequency package

Claims (1)

[Claims] 1. An insulating substrate having a metal layer on a lower surface, and an insulating frame joined to an upper surface of the insulating substrate and having a space inside for accommodating a high-frequency circuit or a semiconductor element mounted on the upper surface of the insulating substrate. A member, a signal line formed on the upper surface of the insulating substrate from the inside to the outside of the insulating frame member, a part of which is sandwiched between the insulating substrate and the insulating frame member; an upper surface of the insulating substrate; A plurality of ground patterns provided on a surface layer or an inner layer of the frame member; and a plurality of vias or through holes for electrically connecting the ground patterns of the plurality of ground patterns to each other. The width of the ground pattern provided inside the insulating frame member is substantially equal to the distance between a plurality of vias or through holes provided inside the insulating frame member. Is equal, the signal line is high-frequency package, characterized in that it is composed of a microstrip line, a strip line, three EMBED microstrip line.