JP2000133735A - Enclosure for high-frequency integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the frequency characteristic of the input/output terminal portion of an enclosure by converting the transmission mode of a signal from a planar transmission-line mode into another transmission mode just before the package-wall portion of a feed-through portion of a high-frequency package, and by reconverting the transmission mode of the signal into the planar transmission-line mode after passing the signal through the package-wall portion. SOLUTION: In a feed-through portion 1 of a high-frequency package, a dielectric mounting type waveguide is provided just below a microstrip line 1a, to couple in an electromagnetic-field way the microstrip line 1a to the waveguide via a slit 1g. In this way, a signal is transmitted by the microstrip line 1a, and the transmission mode of the signal is converted into a dielectric mounting waveguide mode which is coupled thereto via the slit 1g just before the package-wall portion of the feed-through portion 1 to transmit the signal in the waveguide mode when it is passed through the package-wall portion. Furthermore, after passing the signal through the package-wall portion, the waveguide mode is reconverted into the mode of the microstrip line 1a via the slit 1g.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an integrated circuit package for mounting, for example, a microwave or millimeter wave integrated circuit.

[0002]

2. Description of the Related Art The structure of a conventional integrated circuit package will be described with reference to FIG. Reference numeral 3 denotes a package housing which is usually made of metal. 2 is a package wall made of metal. Reference numeral 1 denotes a feed-through portion, which is attached so as to penetrate the package wall in order to supply signals and power to the inside of the package or to take out signals from the inside of the package. The package housing 3 and the package wall 2 are usually hermetically connected by brazing. When actually used, a lid is attached to the upper portion of the package wall by seam welding or soldering, and the package is hermetically sealed. Reference numeral 5 denotes a power supply or a thin metal wire for inputting / outputting a low-frequency signal, and reference numeral 6 denotes a dielectric substrate for supporting the same. Alumina having a dielectric constant of about 10 is usually used for the dielectric substrate. Reference numeral 4 denotes an integrated circuit chip, and 7 denotes wire bonding for connecting the integrated circuit chip 4 to a signal electrode or a power supply electrode.

[0003] Next, a conventional example of a feed-through portion to be improved in characteristics according to the present invention will be described with reference to FIG. FIG. 7B shows the feed-through portion 1 shown in FIG.
FIG. 4 is an enlarged perspective view of FIG. Reference numeral 1a denotes a signal electrode, which normally constitutes a 50Ω microstrip line with a back metallization 1k having a ground potential provided on the back of the dielectric substrate 1b in order to transmit a high-frequency signal without deteriorating characteristics. In order to prevent the signal line 1a from being short-circuited to the package wall 2, a dielectric substrate 1c is usually mounted on the substrate 1b using a co-firing technique. At this time, the feed-through portion in which 1b and 1c are integrated is surrounded by a package wall made of metal on the outside, so that all the connection surfaces with the package wall are necessarily at the ground potential. Therefore, the feedthrough portion itself is surrounded by metallizations of 1h, 1I, 1j, and 1k as shown in FIG. FIG. 9C is a cross-sectional view of a portion of the feedthrough portion surrounded by the package wall. In this case, as shown in the figure, the strip line is entirely surrounded by metal. If the signal line width 1a of this portion is the same as the line width of the microstrip line portion before and after the package wall, the characteristic impedance becomes low, impedance mismatching occurs, and characteristic deterioration occurs. The width is made narrower than the signal line width of the microstrip line portion to improve the characteristics. As the frequency becomes higher and the signal line length and the wavelength of the transmission signal become almost the same, it is important to match the characteristic impedance in this way to secure the characteristics. However, when the frequency is further increased, characteristic degradation occurs due to another factor. The occurrence mechanism of the characteristic degradation will be described with reference to FIG. At a low frequency, the signal is transmitted in a microstrip line mode. However, since the signal line is surrounded by the conductor at the package wall, the waveguide mode is excited when the cutoff frequency is exceeded. The cut-off frequency of the waveguide determines the upper-limit usable frequency of the envelope. The cutoff frequency can be calculated by the following equation.

(Equation 1) Here, f is the cutoff frequency, C is the high speed, a is the length of the waveguide section in the longitudinal direction, and ε is the permittivity of the filled dielectric. If ε _eff is 10 as alumina and a is 1.0 mm, the cutoff frequency is 47 GHz, and a is 0.
If it is 7 mm, it will be 68 GHz. Although the usable frequency band in which “a” is reduced is improved, miniaturization is limited due to manufacturing problems. Currently, only packages up to 60 GHz can be manufactured stably.

As an envelope for an integrated circuit of the second conventional example which solves the problems of the first conventional example, "Millimeter wave package using electromagnetic coupling" by Shinichi Koriyama, Kenji Kitazawa and Mikio Fujii. There is the 1997 IEICE Society Conference C-2-65 ". As shown in FIGS. 10A and 10B, in the integrated circuit package of this paper, a signal line outside the package and a signal line inside the package are formed. These packages are formed on surfaces facing each other, and the connection between them is electromagnetically coupled via slots formed in both common ground conductor plates.
Since there is a form other than the transmission form, it is not a low-pass filter type that connects with a microstrip like the conventional one, but it retains the band-pass filter characteristic with a limited band, but as a package for high-frequency analog elements This is effective as a means for increasing the bandwidth.

However, in such an envelope for an integrated circuit,
The ground conductor is sandwiched between two dielectric substrates, and the heat generated when a power amplifier or the like is mounted on the envelope cannot be escaped properly, causing unnecessary oscillation or deterioration of the integrated circuit. There were problems such as destruction. Further, since the signal line is exposed on the back surface, when the signal line is mounted on a surface mounting substrate, the characteristics of the transmission line change due to the presence of the mounting substrate. For example, the signal line present on the back side constitutes a microstrip line with the ground plane and the metal plane where the slit in the package exists, but if the ground plane exists inside the board to be connected, after mounting the board, It becomes a triplate strip line. At this time, the ground plane inside the envelope and the ground plane inside the board must be short-circuited with sufficiently low impedance in terms of high frequency, but in this case, many via holes and side castellations are required. , The price is high, and the packaging density is low. On the other hand, if the grounding plane and other metal wiring are not placed directly under the envelope, deterioration of the characteristics can be suppressed, but the wiring layout of the board will be greatly restricted, and the mounting density will be greatly reduced. Would. Also, the vertical relationship between the package ground plane and the signal lines
Since it is opposite to the vertical relationship of the mounting board, even if the signal lines can be connected well, a large discontinuity occurs at the connection portion of the ground plane. Therefore, even if desired characteristics are obtained by a single package, it is difficult to realize good high-frequency characteristics when mounted on a board.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the frequency characteristics of the input / output terminals of an envelope by a method that does not degrade the thermal characteristics and does not fluctuate before and after mounting on a substrate. And to improve the bandwidth of the package.

[0007]

A feed-through portion of a high-frequency package using a planar transmission line, a package wall which is structurally indispensable for sealing, for example, a microstrip transmission mode and a dielectric loading type. In order to avoid the characteristic degradation caused by the mixed waveguide mode, the flat transmission line is converted to another transmission mode (waveguide mode) in front of the package wall in the feedthrough section,
After passing through the package wall, it is converted back to the planar transmission line mode. For this reason, since only a single transmission mode contributes to transmission even in the package wall portion, good characteristics can be realized even at high frequencies.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples.

FIG. 1 shows an integrated circuit package according to a first embodiment of the present invention. FIG. 1A is an overall perspective view, and FIG. 1B is an enlarged exploded perspective view of a feedthrough portion. The microstrip line 1a does not penetrate the package wall, but is broken in front. A dielectric-loaded waveguide is disposed immediately below the microstrip line, and is electromagnetically coupled to the microstrip line by a slit 1g. Therefore, the signal is first transmitted by the microstrip line, mode-converted into a dielectric-loaded waveguide connected by a slit before the wall, and transmitted through the wall in the waveguide mode. After passing through the wall, the waveguide mode is converted back to a microstrip line through the slit 1g. For this reason, when passing through the package wall, the microstrip transmission mode and the waveguide mode do not coexist, and the characteristics do not deteriorate at the desired frequency.
A signal is transmitted.

According to the second aspect of the present invention, microstrip and waveguide conversion are performed inside the package. However, as a single package, reverse conversion is not performed outside the package, and the interface of the signal line is kept in the waveguide. It refers to doing. FIG. 2 shows an embodiment of the present invention referred to in claim 2. In the figure, the external terminal of the package on the right is a waveguide. On the other hand, in the package on the left, the external terminals of the package are exposed by microstrip. By arranging the microstrip terminal portion of the left package so as to cover the slit of the right waveguide terminal, the microstrip line and the waveguide are coupled via the slit in a state where the two packages are coupled. become. If both external terminals are microstrip lines, both the signal line and the ground plane must be short-circuited with sufficiently low reactance in terms of high frequency, but by using the present invention of claim 2, only the ground plane can be connected. Since the signal lines are coupled, deterioration of characteristics is significantly reduced. In FIG. 2, the coupling between the waveguide interface package and the microstrip interface package has been described. However, the present invention can also be used for connection between waveguide interfaces.
FIG. 3 shows an embodiment in which the waveguide interfaces are connected to each other. By making the package wall and the waveguide cut surface the same surface, it is possible to connect with high density and low loss when connecting the package. Another embodiment of the connection between the waveguide interfaces is shown in FIG. The right package in the figure has the same structure as the right package in FIG. The external signal terminals of the left package are substantially the same as those of the right package, except that the slit is provided on the lower surface of the waveguide instead of the upper surface. The two terminals are combined by vertically overlapping the two terminals.
In consideration of the connection tolerance, it is preferable that one slit is slightly larger than a desired size of the slit so that the size of the slit on the coupling surface is determined without being affected by the connection tolerance at the time of coupling.

In the embodiment shown in FIG. 4, the upper and lower waveguides are connected through a slit. FIG. 5 shows a structure in which the left and right waveguides are connected.

The embodiment of FIG. 6 is a development of the embodiment of FIG. In the embodiment of FIG. 2, the output and the input are coupled one-to-one, but the present invention can be applied to a one-to-many coupling. In the embodiment of FIG. 6, the output is 1 and the input is 2. In a microwave / millimeter-wave circuit, it is necessary to split a signal at a preceding stage into a plurality of signals for input to a power amplifier, a balance mixer, and the like. The preceding signal is, for example, an output of a preamplifier, an output of an oscillator, or the like. In this case MMI
It was necessary to provide a power distributor, a coupler, etc. on C or another substrate. According to the present invention, the input / output unit of the package can be provided with a power distribution function, which can contribute to a reduction in the number of components.

FIG. 7 is an embodiment showing an application to power supply to an antenna. The rear surface of the dielectric substrate 9 is metallized. A metallization 10 is formed on the upper surface of the dielectric substrate 9. As shown in FIG. 7, the shape of the metallization 10 is composed of a wide rectangular parallelepiped part having an antenna function and a strip conductor part for feeding power to the antenna. Via holes are provided along the outer peripheral portion of the metallization 10, and at each point, a metallization 10
Is short-circuited to the back metallization. Therefore, for example, in the strip conductor portion, a dielectric-loaded waveguide is formed in which the upper surface is covered with a strip-shaped metal, the side surface is surrounded by a via hole, and the lower surface is surrounded by a back metallization 9. Will be. Further, a via hole is also provided inside the metallization 10, and a plurality of dielectric loaded waveguides are arranged in parallel below the metallization 10. In the case of FIG. 7, the plurality of dielectric-loaded waveguides arranged in parallel are arranged in parallel with the dielectric-loaded waveguide of the feeder. Further, a slit 13 is formed on the surface of the waveguides arranged in parallel, that is, the metallization 10, and the slit 13 is formed.
The electromagnetic waves are radiated from the space to the space, and the whole functions as an antenna. The slits 13 are arranged so that the same amount of radiation is emitted from each slit, so that a portion close to the feeder side is dense and sparse as the distance increases. Such antennas have attracted attention because they can suppress the loss due to surface waves and can be made smaller and cheaper than antennas assembled with conventional waveguide systems, but it is difficult to feed power to these antennas. Was. This connection can be easily implemented by using the present invention. As shown in FIG. 7, a slot 12 is provided in the power supply section on the dielectric substrate 9, and connection is performed by using, for example, a package having the structure shown in FIG. 2 of the present invention.

In the embodiments described above, the waveguide is arranged on the lower surface of the ground conductor of the microstrip line when the mode conversion is performed from the microstrip line to the waveguide.
In order to reduce the size, a strip conductor can be arranged at the center of the waveguide opening as shown in FIG. In FIG. 8, the back metallization 1k, the side metallizations 1i and 1h, the top metallization 1j and 1
A dielectric portion surrounded by side metallizations located symmetrically with respect to h and 1i and the strip conductor forms a dielectric loaded waveguide.

[0015]

As described above, according to the present invention, since the transmission of signals inside and outside the integrated circuit enclosure is actively performed by using the waveguide mode, the characteristics at the feedthrough portion are reduced. A wideband envelope can be realized without being restricted by the cutoff frequency of the waveguide. Further, according to the present invention, a main portion of a signal input / output transmission line can be provided on the upper surface of the envelope, so that there are few restrictions on a mounting substrate, high-density mounting is possible, and Since it is possible to directly attach the IC chip mounted on a high heat radiation member such as metal,
It can also be used for devices that generate a large amount of heat, such as power amplifiers. Furthermore, since power distribution and combination can be easily performed without newly providing a power distributor at the input / output terminals, distribution of oscillator output, distribution of power to a plurality of power amplifiers, and distribution of signals for input of a balance mixer are performed. The present invention can be used widely for such purposes. Also, since the present invention can select either a planar circuit or a dielectric loaded waveguide whose input / output is a microstrip as a representative, there is no need to provide a new mode converter when connecting to other devices. In addition, the entire system can be realized compactly with little characteristic deterioration and at low cost.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a package and an enlarged exploded perspective view of a feedthrough portion according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a connection method between packages according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing a connection method between packages and a cross-sectional view of a feed-through portion according to a third embodiment of the present invention.

FIG. 4 is a perspective view showing a connection method between packages according to a fourth embodiment of the present invention.

FIG. 5 is a perspective view showing a connection method between packages according to a fifth embodiment of the present invention.

FIG. 6 is a perspective view showing a connection method between packages according to a sixth embodiment of the present invention.

FIG. 7 is a perspective view showing a connection method between a package and an antenna substrate according to a seventh embodiment of the present invention.

FIG. 8 is an enlarged exploded perspective view of a feedthrough portion according to an eighth embodiment of the present invention.

FIG. 9 is an overall perspective view of a package, an enlarged perspective view of a feed-through portion, and a cross-sectional view of a feed-through portion according to a first conventional example.

FIG. 10 is a top view and a cross-sectional view of an entire package relating to a second conventional example.

[Explanation of symbols]

 Reference Signs List 1 feedthrough 1a microstrip line 1b dielectric substrate 1c dielectric substrate 1d dielectric substrate 1e metallization 1f metallization 1g slit 1h side metallization 1I side metallization 1j top metallization 1k back metallization 2 package wall 3 package housing 4 IC chip 5 power supply Or low frequency electrode 6 dielectric substrate 7 bonding wire 8 ground conductor 9 dielectric substrate 10 metallization 11 via hole 12 slit 13 slit

Claims (3)

[Claims] A housing for mounting and sealing a high-frequency integrated circuit therein; a lid forming a pair with the housing and sealing an integrated circuit mounted inside the housing; In a high frequency integrated circuit envelope including at least one or more input / output terminals and a bias circuit formed inside the housing for supplying power to a circuit, at least one or more of the input / output terminals is a flat surface. It has a circuit-type transmission line structure, which is converted into a dielectric-loaded waveguide mode before the transmission line enters the housing wall, passes through the housing wall, and then enters a dielectric-loaded waveguide mode inside the housing. An envelope for a high-frequency integrated circuit, characterized by being converted from a waveguide mode to a planar circuit type transmission line again. 2. A housing for mounting and sealing a high-frequency integrated circuit therein, a lid forming a pair with the housing and sealing an integrated circuit mounted inside the housing, In a high frequency integrated circuit envelope including a bias circuit formed inside the housing and at least one or more input / output terminals for supplying power to a circuit, at least one or more of the input / output terminals is a package. Inside, it has a planar circuit type transmission line structure, and the transmission line is converted to a dielectric loaded waveguide mode before entering the housing wall, and after passing through the housing wall, it is outside the housing. An enclosure for a high-frequency integrated circuit that has a dielectric-loaded waveguide mode interface. 3. The envelope for a high-frequency integrated circuit according to claim 1, wherein coupling is performed by a slot when converting from a planar circuit type transmission line to a dielectric loaded type waveguide mode.