JP3309056B2 - Package for storing high-frequency elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a package which eliminates the generation of reflection loss, the resonance and the like of an electric signal by a method, wherein a high-frequency transmission line is formed of one pair of main conductor layers which are faced, so as to sandwich a part of a dielectric substrate and of two rows of via-hole groups which connect the main conductor layers electrically and which are arranged and installed at a specific interval in the transmission direction of a signal. SOLUTION: A dielectric substrate which constitutes a package used to house a high-frequency element comprises a mounting part on which the high-frequency element is mounted in the center on its surface, and a high-frequency transmission line 8 by which the high-frequency element is connected to an external electric circuit is formed on the dielectric substrate. The high-frequency transmission line 8 is formed of a pair of main conductor layers 8a, 8b which face each other by sandwiching at least a part of the dielectric substrate, e.g. one layer situated in the uppermost position from amon a plurality of dielectric layers 1a forming the dielectric substrate and of two rows of via-hole groups which connect the pair of main conductor layers 8a, 8b and which are arranged and installed at intervals (c) of 1/2 or lower of a cutoff frequency in the transmission direction of a signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package for storing a high-frequency element having a high-frequency transmission line for transmitting a high-frequency signal such as a microwave or a millimeter wave, and more particularly to an improved transmission characteristic of a high-frequency signal in the high-frequency transmission line. The present invention relates to a high-frequency element storage package.

[0002]

2. Description of the Related Art In recent years, communication systems utilizing high-frequency signals such as microwaves and millimeter waves, for example, systems such as ID card systems, wireless LANs, and vehicle-mounted radars have been actively developed. There is a demand for higher performance of high frequency element storage packages used in the field.

In such a conventional package for accommodating a high-frequency element, as shown in FIG. 6, for example, a cap 12 having a concave portion 12a provided on a lower surface is attached to a dielectric substrate 11 made of alumina ceramic or the like. A high-frequency device 1 such as a high-frequency semiconductor integrated circuit is provided in a space 13 (cavity) formed by the upper surface of
4 is housed and hermetically sealed.

The dielectric substrate 11 has a high-frequency transmission line 1 connecting the high-frequency element 14 and an external electric circuit.
The transmission line 18 is generally a microstrip line, a coplanar line, or the like. In addition, as the high-frequency transmission line 18,
When a microstrip line is adopted, the conductor line is arranged on the upper surface of the dielectric substrate 11, and a ground conductor is arranged inside the dielectric substrate 11. When a coplanar line is adopted, the conductor line and the ground are arranged. Conductor to dielectric substrate 1
1 on the upper surface.

[0005]

However, in this conventional package for housing a high-frequency element, a part of the cap 12 is formed on the upper surface of a part of the dielectric substrate 11 on which the transmission line 18 such as a microstrip line is formed. Has been abutted. Therefore, the transmission line 18 has a different effective permittivity from the contact portion of the cap 12 to the other portion.
As a result, reflection loss or resonance of a signal due to mismatching of characteristic impedance is induced, and transmission characteristics of a high-frequency signal are deteriorated.

Therefore, in order to solve the above-mentioned drawback, the line width of the conductor line forming the transmission line 18 such as a microstrip line and the distance between the conductor line and the ground conductor are adjusted in accordance with the effective permittivity, and the transmission is performed. It has been proposed to keep the characteristic impedance of the line 18 constant throughout it.

However, when assembling the package for accommodating the high-frequency element, the cap 12 is attached to the dielectric substrate 1.
It is practically impossible to accurately align the cap 12 with a predetermined position on the dielectric substrate 11 when the cap 12 is mounted on the substrate 1, and even if a slight misalignment of about several μm occurs, the characteristic impedance is reduced. Inconsistency occurs. For this reason,
The reflection loss and resonance of signals in the high-frequency transmission line 18 cannot be effectively prevented, and satisfactory transmission characteristics have not been obtained.

[0008]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned drawbacks, and a package for storing a high-frequency element according to the present invention is a dielectric package having a high-frequency transmission line for connecting a high-frequency element and an external electric circuit. A high-frequency element housing package comprising a body substrate and a cap, and having a space for housing the high-frequency element therein, wherein the high-frequency transmission line is a pair of opposing members sandwiching at least a part of the dielectric substrate. It is formed of a main conductor layer and two rows of via holes that are electrically connected between the pair of main conductor layers and are arranged in the signal transmission direction at an interval of 1/2 or less of a cutoff wavelength. It is characterized by the following.

In the high-frequency element housing package according to the present invention, a sub-conductor layer electrically connected to the via-hole group is disposed substantially parallel to the main conductor layer between the pair of main conductor layers of the high-frequency transmission line. It is characterized by having made it.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the high-frequency package of the present invention, wherein 1 is a dielectric substrate, 2 is a cap,
A cavity 3 (cavity) for accommodating the high-frequency element 4 is formed by the dielectric substrate 1 and the cap 2.

The dielectric substrate 1 constituting this high-frequency element storage package has a mounting portion on which the high-frequency element 4 is mounted at the center of the upper surface thereof.
Are bonded and fixed via an adhesive (not shown) such as glass, resin, or brazing material.

The dielectric substrate 1 is made of a dielectric material such as alumina ceramics, glass ceramics, aluminum nitride ceramics or the like. For example, when the dielectric substrate 1 is made of alumina ceramics, an organic solvent suitable for a ceramic raw material powder such as alumina, silica or magnesia is used. A plurality of ceramic green sheets are obtained by forming a slurry by adding and mixing a solvent and forming a slurry by employing a conventionally known doctor blade method, calender roll method, or the like, and thereafter, the ceramic green sheet is formed. Are subjected to an appropriate punching process, stacked one above the other, and fired at a high temperature (about 1600 ° C.).

The dielectric substrate 1 is provided with a high-frequency transmission line 8 for connecting the high-frequency element 4 to an external electric circuit (not shown). As shown in FIG. 2, the high-frequency transmission line 8 is opposed to at least a part of the dielectric substrate 1, for example, a topmost one of a plurality of dielectric layers 1 a forming the dielectric substrate 1. Pair of main conductor layers 8
a, 8b and the pair of main conductor layers 8a, 8b are electrically connected to each other, and two rows of via holes are arranged in the signal transmission direction at an interval c equal to or less than の of the cutoff wavelength (λc). (Via holes: 8c).

In such a high-frequency transmission line 8, the two via-hole groups formed between the pair of main conductor layers 8a and 8b each have a cutoff wavelength (λc) of 1 in the signal transmission direction.
/ 2 are arranged at an interval c of not more than / 2, and since an electric wall is formed in a direction perpendicular to the signal transmission direction, the electromagnetic wave can be favorably propagated only in the line forming direction. The region surrounded by the main conductor layers 8a and 8b and the two rows of via holes can function as an axb pseudo waveguide. This makes the high-frequency transmission line 8 suitable for transmitting high-frequency signals such as microwaves and millimeter waves. In the high-frequency transmission line 8, the arrangement pitch c of the via holes 8c is 1/1 / the cutoff wavelength (λc).
If it is larger than 2, when electromagnetic waves are supplied to the high-frequency transmission line 8, the electromagnetic waves leak from between the adjacent via holes 8c,
It does not propagate well along the high-frequency transmission line 8. Therefore,
The arrangement pitch c of the via holes 8c needs to be set to 以下 or less of the cutoff wavelength (λc).

The main conductor layers 8a and 8b and the via holes 8c constituting the high-frequency transmission line 8 are formed on the dielectric substrate 1.
Is formed of a high melting point metal material such as tungsten or molybdenum, and these are formed simultaneously when the dielectric substrate 1 is manufactured. That is, a conductive paste containing a metal powder such as tungsten or molybdenum is printed and applied on the surface of the ceramic green sheet serving as the dielectric substrate 1 with a thickness of 5 to 25 μm by employing a conventionally known thick film printing method or the like. At the same time, a conductive paste is buried in a hole previously opened in the ceramic green sheet, and is baked simultaneously with the ceramic green sheet to form a predetermined pattern on the upper surface and inside of the dielectric substrate 1. At this time, it is not necessary to particularly limit the distance a between the pair of main conductor layers 8a and 8b. However, when the TE 10 is used in the single mode, the distance between the pair of main conductor layers 8a and 8b is a, When the interval between via-hole groups in a row is b, a = b / 2
Alternatively, it is preferable to set a so that a = 2b. In this case, the size of each via hole 8c is φ50 to
It is preferable to set the thickness to about 300 μm.

The high-frequency transmission line 8 as described above has one end led out to the vicinity of the high-frequency element 4 disposed in the cavity 3 and the other end led out to the outside of the mounting region of the cap 2.
A connection probe 5 as a terminal is attached to each outlet.

The connection probe 5 functions as a terminal for electrically connecting the high-frequency transmission line 8 to the high-frequency element 4 or an external electric circuit via the bonding wire 6. Since the upper surface is an H plane parallel to the magnetic field and the side surface is an E plane parallel to the electric field, the length of the connection probe 5 introduced into the high-frequency transmission line 8 is set to be about １ ／ of the signal wavelength. If set, the connection probe 5 can function as a quarter-wave monopole antenna, and the high-frequency transmission line 8 can be connected well to the high-frequency element 4 and an external electric circuit. The pseudo waveguide type high frequency transmission line 8 may be connected to another transmission line such as a microstrip line or a coplanar line using a slot.

Further, a cap 2 having a concave portion 2a on the lower surface is attached to the upper portion of the dielectric substrate 1 via an adhesive (not shown) such as glass, resin, brazing material or the like. A space 3 for accommodating the high-frequency element 4 is formed between the substrate 1 and the cap 2, and the high-frequency element 4 is hermetically accommodated.

The cap 2 is made of the same dielectric material as the above-described dielectric substrate 1 or a metal material having good heat dissipation. The dielectric around which the high-frequency transmission line 8 is formed around the recess 2a is formed. The dielectric substrate 1 is brought into contact with the upper surface of the dielectric substrate 1 by bonding the corresponding contact portion to the upper surface of the dielectric substrate 1 via an adhesive (not shown) such as glass, resin, or brazing material. Mounted on top.

When the cap 2 is made of, for example, alumina ceramics, similarly to the dielectric substrate 1, ceramic green sheets punched into a predetermined shape are laminated and fired at a high temperature to form the recesses 2 on the lower surface.
It is formed in a predetermined shape having a.

In the above-described package for housing a high-frequency element, the high-frequency transmission line 8 provided on the dielectric substrate 1 has a function equivalent to that of the waveguide, and the dielectric constant of a member disposed therearound. The characteristic impedance does not change even if the thickness and the like are partially different. For this reason,
Even if a part of the cap 2 abuts on the high-frequency transmission line 18, no mismatch of the characteristic impedance occurs near the corresponding contact portion or the like. Signals can be transmitted very well.

Moreover, in this case, in assembling the package for housing the high-frequency element, it is not necessary to position the cap 2 with respect to the dielectric substrate 1 with high accuracy as in the conventional example, and the assembling work becomes extremely simple. .

The present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention. For example, as shown in FIG. The high-frequency transmission line 8 formed in the substrate 1 may be formed in a lower region of the dielectric substrate 1,
In this case, the pair of main conductor layers 8a and 8
Since b does not come into contact with the cap 2, better hermetic sealing is possible.

As shown in FIG. 4, a terminal for external connection is provided on the lower surface of the dielectric substrate 1 and is connected to an external wiring substrate P via a solder ball 9, or as shown in FIG.
As shown in the figure, a pair of main conductor layers 8 of the high-frequency transmission line 8 are provided.
A sub-conductor layer 8d substantially parallel to the main conductor layers 8a and 8b may be formed between the sub-conductor layers 8a and 8b so as to be connected to the via holes 8c. Since the holes 8c and the sub-conductor layers 8d form a fine lattice, the effect of blocking electromagnetic waves can be more effectively enhanced.

[0025]

According to the package for housing a high-frequency element of the present invention, the high-frequency transmission line provided on the dielectric substrate has a function equivalent to that of the waveguide, and the dielectric constant of the member disposed therearound. The characteristic impedance is kept constant even if the thickness and the like are partially different. For this reason, even if a part of the cap is in contact with the high-frequency transmission line, there is no occurrence of characteristic impedance mismatch in the vicinity of the corresponding contact portion, etc.
A high-frequency signal can be transmitted very satisfactorily without any occurrence of reflection loss or resonance of the electric signal.

Moreover, in assembling the high-frequency element housing package, it is not necessary to align the cap with the dielectric substrate with high accuracy as in the conventional example, and the assembling work becomes extremely simple.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a high-frequency element housing package of the present invention.

FIG. 2 is a perspective view of a high-frequency transmission line used in the high-frequency element housing package of FIG. 1;

FIG. 3 is a cross-sectional view showing a modification of the high frequency element housing package of the present invention.

FIG. 4 is a cross-sectional view showing a modification of the high-frequency element housing package of the present invention.

FIG. 5 is a perspective view of a high-frequency transmission line used in a high-frequency element housing package according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a conventional package for storing a high-frequency element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Dielectric substrate 2 ... Cap 3 ... Empty space 4 ... High frequency element 8 ... High frequency transmission line

Claims (2)

(57) [Claims] A high-frequency element storage package comprising a dielectric substrate provided with a high-frequency transmission line for connecting a high-frequency element and an external electric circuit, and a cap, and having a space for accommodating the high-frequency element therein. The high-frequency transmission line electrically connects the pair of main conductor layers opposed to each other with at least a part of the dielectric substrate therebetween, and connects the pair of main conductor layers with each other in the signal transmission direction by 1 / の of the cutoff wavelength. A high frequency element storage package, comprising: two rows of via holes arranged at an interval of 2 or less. 2. The semiconductor device according to claim 1, wherein a sub-conductor layer electrically connected to said via-hole group is disposed substantially parallel to said main conductor layer between said pair of main conductor layers of said high-frequency transmission line. 2. The package for storing a high-frequency element according to claim 1.