JPH08102509A - Hybrid microwave integrated circuit - Google Patents

Abstract

PURPOSE: To obtain a hybrid microwave integrated circuit employing a multilayer dielectric board in which the characteristics and reliability are enhanced by separating the electric shield from the hermetic seal structure required for ensuring the reliability of semiconductor element. CONSTITUTION: Electric shield of conventional structure is provided by making a hole in a dielectric for signal transmission above the intermediate layer, mounting a semiconductor element therein, and covering the ground face of the removed upper face with a conductor plate 13. Hermetic seal structure covers the electrically sealed part from above by welding a metal cap 15 to the base plate to form a seal ring, for example.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave integrated circuit, and more particularly to a composite microwave integrated circuit used for a microwave communication device equipped with a plurality of semiconductor chips using a dielectric multilayer substrate.

[0002]

2. Description of the Related Art FIG. 4 shows an entire microwave integrated circuit using a conventional dielectric substrate.

In FIG. 1, a multilayer multilayer dielectric substrate (SUB) 1 made of ceramic or the like superposed in multiple layers is welded to a metal base plate 2. The base plate 2
Not only for strengthening the shield, but also for improving the heat dissipation characteristics and playing a role of mechanical strength.

A voltage controlled oscillator (VCO) 3, an amplifier (AMP) 4, a prescaler (P) composed of active machine elements such as a monolithic microwave integrated circuit (MMIC), an IC, a transistor, and a diode in the SUB1.
SC) 5, mixer (MIX) 6, variable attenuator (AT)
T) 7, a power amplifier (PA) 8, an active circuit such as a detector (DET) 9, a directional coupler (DC) 10 formed by a pattern such as a strip line, a micro strip line, a coplanar line, and a band pass. Filter (B
Passive circuits such as a PF) 11 and a low-pass filter (LPF) 12 are accommodated and electrically connected to each other, and an active circuit portion is shielded by a conductor lid (CAP) 13.

[0005] Further, the connection terminal with the outside has a contact for connection formed in a concave portion provided on the back surface, and is connected to the outside via a connector having a dedicated connection pin which is pressurized by a spring. ing.

Next, with regard to the electrical connection of the present structure, the dielectric substrate 1 has a ground plane formed in an upper layer and a lower layer, and a signal circuit composed of a conductor layer for signal transmission is formed in an intermediate layer. A shield is formed around the signal circuit by a through hole and a via hole that short-circuit two ground planes along the signal circuit. In this, active functional elements and passive elements are electrically connected and integrated. This conventional microwave integrated circuit using a dielectric multilayer substrate is disclosed in, for example, 1993 Patent Application No. 26921.
No. 7. In the structure described above, a dielectric material above the middle layer for signal transmission is cut to form a hole, a semiconductor element such as MMIC is mounted, and the removed ground surface of the upper surface is covered with a conductor plate 13 (cavity). Structure), it has a structure that takes an electrical shield. When the cavity structure has a rectangular parallelepiped shape, the width (W) of the cavity in the direction orthogonal to the signal propagation direction in the cavity is defined as the waveguide mode of propagation in the cavity when the wavelength of the used frequency f ₀ is λ _0. W <2λ to suppress
Must be ₀ . Due to this size limitation, in order to mount many functional elements such as a composite microwave integrated circuit, the cavities must be separated for each element and many cavities are required.

[0007]

However, in the case of this conventional structure, an electric shield and a hermetic sealing structure for ensuring the reliability of the semiconductor are simultaneously obtained by sealing with this conductor plate. It is necessary to perform the sealing with the conductive plate so as to satisfy the hermetic sealing condition which is stricter than the electrically necessary shielding condition. Therefore, in the case of a composite microwave integrated circuit with a large number of cavities, it is difficult to use a sealing method such as welding on the dielectric multi-layer substrate, and it is necessary to use brazing with poor airtightness. This has been a cause of reduction in manufacturing yield of microwave integrated circuits.

[0008]

The present invention is characterized in that it has a structure in which a shield that is electrically necessary and a hermetically sealed semiconductor are separated from each other. The electric shield has a structure similar to the conventional structure, in which a hole is formed by cutting the dielectric above the middle layer for signal transmission, a semiconductor element is mounted, and the removed ground plane on the upper surface is covered with a conductor plate. The hermetically sealed structure is formed as a structure in which a seal ring or the like for welding a metal cap is formed on a base plate to cover the electric shield portion from above.

[0009]

FIG. 1 shows an embodiment of the present invention. In the figure, portions that are the same as those in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted. Dielectric substrate 1
In order to take an electrical shield, a hole is formed in the dielectric above the middle layer for signal transmission.
Is mounted inside, and the ground plane on the removed upper surface is covered with the conductor plate 13. On the other hand, for the airtight shield, the metal cap 15 is formed on the base plate 2 by means such as welding. As a result, since the conductor plate 13 only needs to be electrically shielded, it is not necessary to satisfy strict hermetic sealing conditions as in the related art, and simple attachment using a conductive adhesive or the like is sufficient. On the other hand, the metal cap 15 can have a completely hermetically sealed structure by welding or the like. In this case, the output RF interface,
Further, the power supply interface and the like have a structure in which the power is drawn out to the mounting surface of the base plate 2 via the dielectric multilayer substrate opposite to the cavity surface requiring hermetic sealing to obtain an output.

That is, the coaxial connector 16 is attached to the back surface of the base plate 2. The center conductor of this coaxial connector is connected to each high-frequency signal via the base plate and the dielectric substrate 1.

The connector 17 is similarly attached to the back surface of the base plate 2 and is connected to a power supply or a control signal.

Since the leak of the high-frequency signal may become a problem due to the attachment of the connector 17, the high-frequency signal, the power supply, and the control signal are frequency-multiplexed and the multiplexed signal is supplied to the coaxial connector 16. Can also be transmitted.

As for the electrical connection of the present structure, the upper and lower ground planes are formed on the dielectric substrate 1 as in the prior art, and a signal circuit comprising a conductor layer for signal transmission is formed in the middle layer. It is formed. Along the signal circuit, a shield surrounding the signal circuit is formed by a through hole and a via hole that short-circuit two ground planes to each other. The active function element and the passive element are electrically connected to each other and integrated.

Although the conductor plate 13 described above has a different shape for each of a plurality of electric circuits, a large number of conductor plates are required. An electromagnetic shield cap can also be used.

FIG. 2 shows another embodiment of the present invention using one electromagnetic shield cap.

FIG. 1 shows a configuration in which one electromagnetic shield cap 18 is mounted on a dielectric substrate 1 and a plurality of electric circuits are shielded by making contact with a ground plane on an upper layer of the dielectric substrate. . As shown in FIG. 3, the electromagnetic shield cap 18 is in contact with the upper ground plane of the dielectric substrate, as shown in FIG.
The shield plate 19 is attached to the. In this case, the dielectric substrate 1 can have holes of different shapes for each circuit as in the conventional configuration, but each circuit can be mounted in a plurality of grid-like holes for more versatility.

In the present embodiment, PA8 and DET9 are mounted inside the SUB1 in lattice holes arranged at regular intervals, and if no components need to be mounted, those parts are not mounted. As a result, there is an effect that the dielectric substrate 1 can be generally used for various circuits.

In the embodiment described above, a configuration is shown in which a plurality of high-frequency circuits are mounted in a dielectric substrate. However, in the case of a low-frequency circuit, there is no need for an electromagnetic shield. In this case, it is a matter of course that an airtight shield can be obtained by using the metal cap 15 without using the conductor plate 13 and the electromagnetic shield cap 18.

[0019]

According to the present invention, the yield of composite microwave integrated circuits can be improved by separating the method of electric shielding and the method of hermetic sealing shield, and the reliability can be increased by ensuring hermetic sealing. Will be possible.

[Brief description of drawings]

FIG. 1 is a first embodiment of the present invention.

FIG. 2 is a second embodiment of the present invention.

FIG. 3 is a view showing an electromagnetic shield cap of the present invention.

FIG. 4 is a diagram of a composite microwave integrated circuit according to a conventional invention.

[Explanation of symbols]

 Reference Signs List 1 laminated multilayer dielectric substrate 2 base plate 3 voltage controlled oscillator (VCO) 4 amplifier (AMP) 5 prescaler (PSC) 6 mixer (MIX) 7 variable attenuator (ATT) 8 power amplifier (PA) 9 detector (DET) 10 Directional coupler (DC) 11 Band pass filter (BPF) 12 Low pass filter (LPF) 13 Conductor cover (CAP) 14 Cavity part 15 Metal cap 16 RF connector 17 Power connector 18 Electromagnetic shield cap 19 Shield plate

Claims (6)

[Claims] 1. A composite microwave integrated circuit in which a plurality of high-frequency circuits are mounted on a multi-layered dielectric substrate, a metallic base plate welded to the dielectric substrate and fixing the dielectric substrate; A plurality of holes obtained by forming a ground plane by a conductor layer on the two layers of the dielectric substrate in an upper layer and a lower layer, and cutting a dielectric above an intermediate portion between the upper layer and the lower layer; A composite micro-computer comprising: a conductor plate covering an upper layer ground surface of the dielectric substrate on which the high-frequency circuit is mounted for each hole; and a metal cap connected to the base plate and covering the entire dielectric substrate. Wave integrated circuit. 2. A composite microwave integrated circuit in which a plurality of high-frequency circuits are mounted in dielectric substrates laminated in multiple layers, wherein a metallic base plate is welded to the dielectric substrate to fix the dielectric substrate, A plurality of holes obtained by forming ground planes of conductor layers on two layers of the dielectric substrate in an upper layer and a lower layer, and cutting the dielectric above an intermediate portion between the upper layer and the lower layer; An electromagnetic shield cap, which is connected to the upper ground plane of the dielectric substrate having the high-frequency circuit mounted in the hole and covers the entire dielectric substrate, and a metal cap, which is connected to the base plate and covers the entire dielectric substrate, are provided. A composite microwave integrated circuit characterized in that 3. The composite microwave integrated circuit according to claim 1, wherein said metal cap is welded to said base plate and hermetically sealed. 4. The composite microwave integrated circuit according to claim 1, wherein a connector for connecting to the high-frequency circuit is mounted on a surface of the base plate opposite to a surface on which the dielectric substrate is mounted. 5. The composite microwave integrated circuit according to claim 1, wherein the conductor plate and the electromagnetic shield cap are attached to the ground plane of the upper layer by using a conductive adhesive. 6. The conductor plate and the electromagnetic shield cap are
2. The composite microwave integrated circuit according to claim 1, wherein the circuit mounted in the dielectric substrate is not attached when the circuit is a low-frequency circuit.