JP2806343B2 - Multi-chip module and its chip carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multichip module and a chip carrier thereof, and more particularly, to a multichip module having a circuit of a chip carrier type mounted on a circuit board.

[0002]

2. Description of the Related Art With the miniaturization of portable telephones, a multi-chip module as a high frequency (RF) signal amplifier used therein is also required to be small and thin.
The structure of an example of a conventional multichip module will be described with reference to an exploded perspective view of FIG. 5 and a sectional view of FIG.

In this multi-chip module, as shown in FIG. 5, a ceramic or resin circuit board 2 is placed on a metal heat sink 3 on which a flat plate or both ends are bent as shown in FIG. Fixed. The back surface of the circuit board 2 is metallized with copper or the like to be electrically connected to the heat sink 3. The circuit board 2 has a hole (cavity) formed therein for inserting the chip carrier 1 on which a semiconductor is mounted, and the bottom metal portion serving as one of the electrodes of the chip carrier 1 is attached to the heat sink 3 together with the circuit board 2. Connected with solder such as solder.

The other lead electrode 8 of the chip carrier 1 is connected to a circuit pattern 11 formed by printing or etching a thick film on the circuit board 2 when the chip carrier 1 is inserted into the circuit board 2 to form a circuit. On the circuit board 2, chip components 10 such as chip resistors, capacitors, inductors, etc., which constitute a circuit together with the circuit pattern 11, are formed.
1 and fixed with solder. In order to protect the circuit pattern 11 on the circuit board 2 from oxidation or the like, it is coated with a dielectric or plated with gold or the like having good oxidation resistance (for example, three layers of Cu-Ni-Au, each having a thickness of 18 μm, 3 to 5 μm, about 0.03 μm).

A lead 12 is attached to the end of the circuit board 2 as an interface with the outside (power supply and input / output signal lines). The lead 12 has a clip shape that sandwiches the circuit board 2 at the position of the circuit pattern 10 provided at the end of the circuit board 2, and a part of the lead 12 is pulled out from the end of the circuit board 2 by about 2 mm. Connected to an external line.

The circuit components formed on the heat sink 3 are protected by attaching a metal cover 4 to the heat sink 3, and the cover 4 prevents signal radiation from an internal RF circuit.

As shown in FIG. 6C, the cover 4 is engaged with its own fitting portion 14A and a fitting portion 14B provided on the heat sink 3, and is mechanically fitted by utilizing the elasticity of metal. The joint is tightened. The cover 4 and the heat sink 3 are electrically connected to each other by the contact due to the fitting of the metal portion.

FIG. 6B shows the structure of the chip carrier 1 mounted on the multi-chip module. The outer peripheral portion of the upper surface of the metal base 6 is made lower than the central portion, and a thin plate 13 made of ceramic or insulator and having a thickness of about 0.6 mm is placed on this portion. The rear surface of the thin plate 13 is metallized so as to be connected to the metal base 6.
Both are bonded with solder. The lead electrode 8 of the chip carrier 1 is attached to the upper surface of the thin plate 13, but the upper surface of the thin plate 13 is metallized similarly to the back surface, and the lead electrode 8 is bonded at that portion. A semiconductor, for example, a GaAs FET is mounted on the upper surface of the base 6, and the electrode on the upper surface of the semiconductor and the lead electrode 8 of the chip carrier 1 are connected by a bonding wire. Resin is potted from above the chip carrier 1 to protect the semiconductor and the bonding wires in the chip carrier 1.

[0009]

In this conventional multi-chip module, in order to make the potential of the cover 4 the same as that of the heat sink 3, each fitting portion 1 for fixing the cover 4 is used.
Although the contact due to the meshing of 4A and 14B is used as an electrical connection, the electrical connection is incomplete and there is a problem that the electrical characteristics of the multi-chip module become unstable. In order to reduce the thickness of the multi-chip module, the circuit components 1
0 was in danger of contacting the cover due to slight deformation of the cover 4.

An object of the present invention is to solve these problems,
An object of the present invention is to provide a multi-chip module that ensures contact with a cover and prevents contact with components and the like due to deformation of the cover.

[0011]

According to the present invention, there is provided a circuit board on which a chip carrier on which a high-frequency element is mounted and a high-frequency component are mounted and wiring for connecting the components is formed, and a metal radiator on which the circuit board is mounted is provided. In a multi-chip module including a plate and a cap-shaped cover made of a conductive member that has a fitting portion fitted with the metal heat sink and covers the circuit board, the chip carrier on which the high-frequency element is mounted is: The mounting surface is formed of a ground electrode extending forward, and the ground electrode is configured to be in contact with and connected to the cover.

The chip carrier of the present invention comprises a metal base on which a high-frequency element is mounted and forms a ground electrode; an insulating substrate surrounding the mounting portion of the high-frequency element on the metal base; In a chip carrier having a lead drawn out of a device, the metal base has a ground electrode extending on a mounting surface of the high-frequency device over an outer periphery of the insulating substrate excluding the lead portion. And

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a multichip module according to an embodiment of the present invention. In this multi-chip module, a circuit board 2 made of a dielectric material is placed on a heat sink (radiator plate) 3, and a metal film is attached to the back surface of the circuit board 2. The heat sink 3 and the circuit board 2 are soldered. Mated. The circuit board 2 is provided with a through hole 5 for mounting the chip carrier 1. The chip carrier 1 is inserted into the through hole 5, and the lower surface of the bottom pace 6, which is a ground electrode, is connected to the heat sink 3 and solder. Connected. A circuit pattern 11 is formed on the upper surface of the circuit board 2, and chip components (resistors, capacitors, etc.) 10 constituting the circuit are mounted and fixed with solder.

After mounting these parts 10, the cover 4
6C, the cover 4 is fixed and electrically connected by fitting into the fitting portions 14A and 14B at the front and rear portions of the heat sink 3 as in FIG. Further, as shown in FIG. 2B, the upper portion of the chip carrier 1 has a height that comes into contact with the inner surface of the upper portion of the cover 4 when the cover 4 is attached.
As shown in FIG. 2A, the upper portion of the chip carrier 1 is electrically connected to the base 6 serving as the ground electrode at the lower portion thereof. 4 and the electrical connection is established.
At this time, the chip carrier 1 has a structure for supporting the cover 4.

FIG. 3 is an exploded perspective view showing another embodiment of the present invention. In this embodiment, the chip carrier 1
2A, the ground electrode 15 electrically connected to the base 6 of the chip carrier 1 has a structure in which the space in the multi-chip module is divided into a plurality of parts on a circuit. The ground electrode 15 of the carrier 1 is electrically and structurally connected to the cover 4 as in FIG. In the present embodiment, not only the connection to the upper portion of the cover 4 but also the connection to the cover 4 on the rear surface and the front surface are performed at the same time.

Next, the chip carrier 1 used in the present invention will be described with reference to FIGS. When the multi-chip module is assembled, the metal base 6 serving as the ground electrode 15 designed to match the height between the upper surface of the heat sink 3 and the upper inner surface of the cover 4 has a sectional structure as shown in FIG. I have. On the inside, as shown in FIG. 4, a thin dielectric plate 13 surrounds the semiconductor element.
Is attached by brazing or the like. On this thin plate 13, a lead electrode 8 for extraction is attached. Ground electrode 1
5 is cut in the height direction at the position where the lead electrode 8 is pulled out, and the lead electrode 8 is drawn out from the gap between the ground electrode 15.

The shape of the ground electrode 15 can be either the side from which the lead electrode 8 is drawn out or along the entire outer periphery, but the height is as described above. Sometimes, the height is set to a level at which the upper surface of the ground electrode 15 contacts the upper inside of the cover 4.

[0018]

As described above, according to the present invention, in the chip carrier in the multi-chip module, the ground potential of the chip carrier is electrically connected simultaneously with the cover and the heat sink so that the potential of the cover is stabilized. And the performance of the multichip module is stabilized. Further, since the cover is structurally supported by the chip carrier, the cover is prevented from being deformed, and the short circuit of the internal circuit due to the deformation of the cover can be prevented. Furthermore, by further increasing the size of the upper ground electrode of the chip carrier and dividing the space in the multi-chip module into a plurality of parts, the isolation of the circuit in the multi-chip module is improved, and the stability of the circuit is improved. There is also an effect.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a configuration of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the chip carrier and the multi-chip module of FIG.

FIG. 3 is an exploded perspective view of another embodiment of the present invention.

FIG. 4 is a top view of the chip carrier of FIG. 3;

FIG. 5 is an exploded perspective view showing a configuration of a conventional multichip module.

6 is a cross-sectional view of a multi-chip module portion, a chip carrier, and a case portion of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 chip carrier 2 circuit board 3 heat sink 4 cover 5 (substrate) through hole 6 base 7 solder plating 8 lead electrode 9 resin 10 chip component 11 circuit pattern 12 lead 13 insulating plate thin plate 14A, 14B fitting portion 15 ground electrode

Claims (4)

(57) [Claims] A circuit board on which a chip carrier on which a high-frequency element is mounted and a high-frequency component are mounted and wiring for connecting the chip carrier is formed; a metal heat sink on which the circuit board is mounted;
In the multi-chip module including the metal heat dissipation plate and a cap-shaped cover made of a conductive member that covers the circuit board and has a fitting portion, the chip carrier on which the high-frequency element is mounted has a mounting surface A multi-chip module, comprising a ground electrode extending forward thereof, the ground electrode being in contact with and connected to the cover. 2. The multi-chip module according to claim 1, wherein the chip carrier is disposed in contact with a metal heat sink in a through hole formed in the circuit board. 3. The multi-chip module according to claim 1, wherein a ground electrode of the chip carrier separates a circuit board on which the chip carrier is mounted from the cap-shaped cover. 4. A metal base on which a high-frequency element is mounted to form a ground electrode, an insulating substrate surrounding the mounting portion of the high-frequency element of the metal base, and a lead drawn out of the high-frequency element on the insulating substrate. Wherein the metal base has a ground electrode extending on the mounting surface of the high-frequency element over the outer periphery of the insulating substrate excluding the lead portion.